Gaussian mixture models for signal mapping and positioning

Maps of RSS from a wireless transmitter can be used for positioning or for planning wireless infrastructure. The RSS values measured at a single point are not always the same, but follow some distribution, which vary from point to point. In existing approaches in the literature this variation is neglected or its mapping requires making many measurements at every point, which makes the measurement collection very laborious. We propose to use GMs for modeling joint distributions of the position and the RSS value. The proposed model is more versatile than methods found in the literature as it models the joint distribution of RSS measurements and the location space. This allows us to model the distributions of RSS values in every point of space without making many measurement in every point. In addition, GMs allow us to compute conditional probabilities and posteriors of position in closed form. The proposed models can model any RSS attenuation pattern, which is useful for positioning in multifloor buildings. Our tests with WLAN signals show that positioning with the proposed algorithm provides accurate position estimates. We conclude that the proposed algorithm can provide useful information about distributions of RSS values for different applications.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Computing Sciences, Research group: Automation and Systems Theory, Aalto University, University of Liverpool, Universidad Antonio de Nebrija, Uppsala University
Contributors: Raitoharju, M., García-Fernández, F., Hostettler, R., Piché, R., Särkkä, S.
Publication date: 1 Mar 2020
Peer-reviewed: Yes
Early online date: 10 Oct 2019

Publication information

Journal: Signal Processing
Volume: 168
Article number: 107330
ISSN (Print): 0165-1684
Original language: English
ASJC Scopus subject areas: Control and Systems Engineering, Software, Signal Processing, Computer Vision and Pattern Recognition, Electrical and Electronic Engineering
Keywords: Gaussian mixtures, Indoor positioning, RSS, Signal mapping, Statistical modeling
URLs: 
Source: Scopus
Source ID: 85073693932

Research output: Contribution to journalArticleScientificpeer-review

Fusion enhancement for tracking of respiratory rate through intrinsic mode functions in photoplethysmography

Decline in respiratory regulation demonstrates the primary forewarning for the onset of physiological aberrations. In clinical environment, the obtrusive nature and cost of instrumentation have retarded the integration of continuous respiration monitoring for standard practice. Photoplethysmography (PPG) presents a non-invasive, optical method of assessing blood flow dynamics in peripheral vasculature. Incidentally, respiration couples as a surrogate constituent in PPG signal, justifying respiratory rate (RR) estimation. The physiological processes of respiration emerge as distinctive oscillations that are fluctuations in various parameters extracted from PPG signal. We propose a novel algorithm designed to account for intermittent diminishment of the respiration induced variabilities (RIV) by a fusion-based enhancement of wavelet synchrosqueezed spectra. We have combined the information on intrinsic mode functions (IMF) of five RIVs to enhance mutually occurring, instantaneous frequencies of the spectra. The respiration rate estimate is obtained by tracking the spectral ridges with a particle filter. We have evaluated the method with a dataset recorded from 29 young adult subjects (mean: 24.17 y, SD: 4.19 y) containing diverse, voluntary, and periodically metronome-assisted respiratory patterns. Bayesian inference on fusion-enhanced Respiration Induced Frequency Variability (RIFV) indicated MAE and RMSE of 1.764 and 3.996 BPM, respectively. The fusion approach was deemed to improve MAE and RMSE of RIFV by 0.185 BPM (95% HDI: 0.0285-0.3488, effect size: 0.548) and 0.250 BPM (95% HDI: 0.0733-0.431, effect size: 0.653), respectively, with further pronounced improvements to other RIVs. We conclude that the fusion of variability signals proves important to IMF localization in the spectral estimation of RR.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: BioMediTech, Research group: Sensor Technology and Biomeasurements (STB)
Contributors: Pirhonen, M., Vehkaoja, A.
Number of pages: 11
Publication date: 2020
Peer-reviewed: Yes

Publication information

Journal: Biomedical Signal Processing and Control
Volume: 59
Article number: 101887
ISSN (Print): 1746-8094
Original language: English
ASJC Scopus subject areas: Signal Processing, Health Informatics
Keywords: Particle filtering, Photoplethysmography, Respiration rate, Spectral fusion, Synchrosqueezing
URLs: 

Bibliographical note

INT=bmte,"Pirhonen, Mikko"

Source: Scopus
Source ID: 85079696106

Research output: Contribution to journalArticleScientificpeer-review

Online Spectrogram Inversion for Low-Latency Audio Source Separation

Audio source separation is usually achieved by estimating the short-time Fourier transform (STFT) magnitude of each source, and then applying a spectrogram inversion algorithm to retrieve time-domain signals. In particular, the multiple input spectrogram inversion (MISI) algorithm has been exploited successfully in several recent works. However, this algorithm suffers from two drawbacks, which we address in this letter. First, it has originally been introduced in a heuristic fashion: we propose here a rigorous optimization framework in which MISI is derived, thus proving the convergence of this algorithm. Besides, while MISI operates offline, we propose here an online version of MISI called oMISI, which is suitable for low-latency source separation, an important requirement for e.g., hearing aids applications. oMISI also allows one to use alternative phase initialization schemes exploiting the temporal structure of audio signals. Experiments conducted on a speech separation task show that oMISI performs as well as its offline counterpart, thus demonstrating its potential for real-time source separation.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Research group: Audio research group - ARG, Computing Sciences, University of Toulouse, INP, LAAS-CNRS
Contributors: Magron, P., Virtanen, T.
Number of pages: 5
Pages: 306-310
Publication date: 2020
Peer-reviewed: Yes

Publication information

Journal: IEEE Signal Processing Letters
Volume: 27
ISSN (Print): 1070-9908
Original language: English
ASJC Scopus subject areas: Signal Processing, Electrical and Electronic Engineering, Applied Mathematics
Keywords: Audio source separation, low-latency, online spectrogram inversion, phase recovery, sinusoidal modeling

Bibliographical note

EXT="Magron, Paul"

Source: Scopus
Source ID: 85080104357

Research output: Contribution to journalArticleScientificpeer-review

Functional electrical stimulation for facial pacing: Effects of waveforms on movement intensity and ratings of discomfort

Facial pacing systems aim to reanimate paralyzed facial muscles with electrical stimulation. To aid the development of such systems, the frontalis muscle responsible for eyebrow raising was transcutaneously stimulated in 12 healthy participants using four waveforms: square wave, square wavelet, sine wave, and sinusoidal wavelet. The aim was to investigate the effects of the waveform on muscle activation magnitude, perceived discomfort, and the relationship between the stimulus signal amplitude and the magnitude of evoked movement. The magnitude of movement was measured offline using video recordings and compared to the magnitude of maximum voluntary movement (MVM) of eyebrows. Results showed that stimulations evoked forehead movement at a magnitude comparable to the MVM in 67% of the participants and close to comparable (80% of the MVM) in 92%. All the waveforms were equally successful in evoking movements. Perceived discomfort did not differ between the waveforms in relation to the movement magnitude, but some individual preferences did exist. Further, regression analysis showed a statistically significant linear relation between stimulation amplitudes and the evoked movement in 98% of the cases. As the waveforms performed equally well in evoking muscle activity, the waveform in pacing systems could be selected by emphasizing technical aspects such as the possibility to suppress stimulation artifacts from simultaneous electromyography measurement.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Research group: Sensor Technology and Biomeasurements (STB), BioMediTech, Tampere University, Tampere University Hospital
Contributors: Ilves, M., Rantanen, V., Venesvirta, H., Lylykangas, J., Vehkaoja, A., Mäkelä, E., Verho, J., Lekkala, J., Rautiainen, M., Surakka, V.
Number of pages: 7
Publication date: 2020
Peer-reviewed: Yes

Publication information

Journal: Biomedical Signal Processing and Control
Volume: 60
Article number: 101992
ISSN (Print): 1746-8094
Original language: English
ASJC Scopus subject areas: Signal Processing, Health Informatics
Keywords: Comfort, Electrical stimulation, Facial muscle, Frontalis, Unilateral facial paresis, Waveform

Bibliographical note

DUPL=53532026

Source: Scopus
Source ID: 85084080389

Research output: Contribution to journalArticleScientificpeer-review

Compressive sensed video recovery via iterative thresholding with random transforms

The authors consider the problem of compressive sensed video recovery via iterative thresholding algorithm. Traditionally, it is assumed that some fixed sparsifying transform is applied at each iteration of the algorithm. In order to improve the recovery performance, at each iteration the thresholding could be applied for different transforms in order to obtain several estimates for each pixel. Then the resulting pixel value is computed based on obtained estimates using simple averaging. However, calculation of the estimates leads to significant increase in reconstruction complexity. Therefore, the authors propose a heuristic approach, where at each iteration only one transform is randomly selected from some set of transforms. First, they present simple examples, when block-based 2D discrete cosine transform is used as the sparsifying transform, and show that the random selection of the block size at each iteration significantly outperforms the case when fixed block size is used. Second, building on these simple examples, they apply the proposed approach when video block-matching and 3D filtering (VBM3D) is used for the thresholding and show that the random transform selection within VBM3D allows to improve the recovery performance as compared with the recovery based on VBM3D with fixed transform.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Computing Sciences, Research group: Computational Imaging-CI, ITMO University, Linköping University, University of Oulu
Contributors: Belyaev, E., Codreanu, M., Juntti, M., Egiazarian, K.
Number of pages: 14
Pages: 1187-1200
Publication date: 2020
Peer-reviewed: Yes

Publication information

Journal: IET Image Processing
Volume: 14
Issue number: 6
ISSN (Print): 1751-9659
Original language: English
ASJC Scopus subject areas: Software, Signal Processing, Computer Vision and Pattern Recognition, Electrical and Electronic Engineering

Bibliographical note

EXT="Belyaev, Evgeny"

Source: Scopus
Source ID: 85084175769

Research output: Contribution to journalArticleScientificpeer-review

Vehicle Attribute Recognition by Appearance: Computer Vision Methods for Vehicle Type, Make and Model Classification

This paper studies vehicle attribute recognition by appearance. In the literature, image-based target recognition has been extensively investigated in many use cases, such as facial recognition, but less so in the field of vehicle attribute recognition. We survey a number of algorithms that identify vehicle properties ranging from coarse-grained level (vehicle type) to fine-grained level (vehicle make and model). Moreover, we discuss two alternative approaches for these tasks, including straightforward classification and a more flexible metric learning method. Furthermore, we design a simulated real-world scenario for vehicle attribute recognition and present an experimental comparison of the two approaches.

General information

Publication status: E-pub ahead of print
MoE publication type: A1 Journal article-refereed
Organisations: Computing Sciences, Research group: Multimedia Research Group - MRG
Contributors: Ni, X., Huttunen, H.
Publication date: 2020
Peer-reviewed: Yes

Publication information

Journal: Journal of Signal Processing Systems
ISSN (Print): 1939-8018
Original language: English
ASJC Scopus subject areas: Control and Systems Engineering, Theoretical Computer Science, Signal Processing, Information Systems, Modelling and Simulation, Hardware and Architecture
Keywords: Image classification, Metric learning, Vehicle attribute recognition
Source: Scopus
Source ID: 85086837300

Research output: Contribution to journalArticleScientificpeer-review

Digital Predistortion for Multiuser Hybrid MIMO at mmWaves

Efficient mitigation of power amplifier (PA) nonlinear distortion in multi-user hybrid precoding based broadband mmWave systems is an open research problem. In this article, we carry out detailed signal and distortion modeling in broadband multi-user hybrid MIMO systems, with a bank of nonlinear PAs in each subarray, while also take the inevitable crosstalk between the antenna/PA branches into account. Building on the derived models, we adopt and describe an efficient closed-loop (CL) digital predistortion (DPD) solution that utilizes only a single-input DPD unit per transmit chain or subarray, despite crosstalk, providing thus substantial complexity-benefit compared to the state-of-the art multi-dimensional DPD solutions. We show that under spatially correlated multipath propagation, each single-input DPD unit can provide linearization towards every intended user, or more generally, towards all spatial directions where coherent propagation is taking place, and that the adopted CL DPD system is robust against crosstalk. Extensive numerical results building on practical measurement-based mmWave PA models are provided, demonstrating and verifying the excellent linearization performance of the overall DPD system in different evaluation scenarios.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Electrical Engineering, Research group: Wireless Communications and Positioning, Zewail City of Science and Technology, Chalmers University of Technology, Lunds Universitet / Lunds Tekniska Högskola
Contributors: Brihuega, A., Anttila, L., Abdelaziz, M., Eriksson, T., Tufvesson, F., Valkama, M.
Number of pages: 16
Pages: 3603-3618
Publication date: 2020
Peer-reviewed: Yes

Publication information

Journal: IEEE Transactions on Signal Processing
Volume: 68
ISSN (Print): 1053-587X
Original language: English
ASJC Scopus subject areas: Signal Processing, Electrical and Electronic Engineering
Keywords: Crosstalk, digital predistortion, hybrid MIMO, large-array transmitters, millimeter wave communications, multi-user MIMO, nonlinear distortion, out-of-band emissions, power amplifiers

Bibliographical note

EXT="Abdelaziz, Mahmoud"

Source: Scopus
Source ID: 85087520842

Research output: Contribution to journalArticleScientificpeer-review

Multimodal subspace support vector data description

In this paper, we propose a novel method for projecting data from multiple modalities to a new subspace optimized for one-class classification. The proposed method iteratively transforms the data from the original feature space of each modality to a new common feature space along with finding a joint compact description of data coming from all the modalities. For data in each modality, we define a separate transformation to map the data from the corresponding feature space to the new optimized subspace by exploiting the available information from the class of interest only. We also propose different regularization strategies for the proposed method and provide both linear and non-linear formulations. The proposed Multimodal Subspace Support Vector Data Description outperforms all the competing methods using data from a single modality or fusing data from all modalities in four out of five datasets.

General information

Publication status: E-pub ahead of print
MoE publication type: A1 Journal article-refereed
Organisations: Computing Sciences, Research group: Multimedia Research Group - MRG, Finnish Environment Institute, Aarhus Universitet
Contributors: Sohrab, F., Raitoharju, J., Iosifidis, A., Gabbouj, M.
Number of pages: 13
Publication date: 2020
Peer-reviewed: Yes

Publication information

Journal: Pattern Recognition
Volume: 110
Article number: 107648
ISSN (Print): 0031-3203
Original language: English
ASJC Scopus subject areas: Software, Signal Processing, Computer Vision and Pattern Recognition, Artificial Intelligence
Keywords: Feature transformation, Multimodal data, One-class classification, Subspace learning, Support vector data description

Bibliographical note

EXT="Iosifidis, Alexandros"

Source: Scopus
Source ID: 85090954677

Research output: Contribution to journalArticleScientificpeer-review

Self-Supervised Light Field Reconstruction Using Shearlet Transform and Cycle Consistency

Shearlet Transform (ST) has been instrumental for the Densely-Sampled Light Field (DSLF) reconstruction, as it sparsifies the underlying Epipolar-Plane Images (EPIs). The sought sparsification is implemented through an iterative regularization, which tends to be slow because of the time spent on domain transformations for dozens of iterations. To overcome this limitation, this letter proposes a novel self-supervised DSLF reconstruction method, CycleST, which employs ST and cycle consistency. Specifically, CycleST is composed of an encoder-decoder network and a residual learning strategy that restore the shearlet coefficients of densely-sampled EPIs using EPI-reconstruction and cycle-consistency losses. CycleST is a self-supervised approach that can be trained solely on Sparsely-Sampled Light Fields (SSLFs) with small disparity ranges (⩽ 8 pixels). Experimental results of DSLF reconstruction on SSLFs with large disparity ranges (16-32 pixels) demonstrate the effectiveness and efficiency of the proposed CycleST method. Furthermore, CycleST achieves ∼ 9x speedup over ST, at least.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Computing Sciences, Research group: 3D MEDIA
Contributors: Gao, Y., Bregovic, R., Gotchev, A.
Number of pages: 5
Pages: 1425-1429
Publication date: 2020
Peer-reviewed: Yes

Publication information

Journal: IEEE Signal Processing Letters
Volume: 27
ISSN (Print): 1070-9908
Original language: English
ASJC Scopus subject areas: Signal Processing, Electrical and Electronic Engineering, Applied Mathematics
Keywords: cycle consistency, Image-based rendering, light field reconstruction, self-supervision, shearlet transform
Source: Scopus
Source ID: 85091167231

Research output: Contribution to journalArticleScientificpeer-review

Bayesian receiver operating characteristic metric for linear classifiers

We propose a novel classifier accuracy metric: the Bayesian Area Under the Receiver Operating Characteristic Curve (CBAUC). The method estimates the area under the ROC curve and is related to the recently proposed Bayesian Error Estimator. The metric can assess the quality of a classifier using only the training dataset without the need for computationally expensive cross-validation. We derive a closed-form solution of the proposed accuracy metric for any linear binary classifier under the Gaussianity assumption, and study the accuracy of the proposed estimator using simulated and real-world data. These experiments confirm that the closed-form CBAUC is both faster and more accurate than conventional AUC estimators.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Research group: Computational Systems Biology, Computing Sciences, AI Virtanen Institute for Molecular Sciences, University of Eastern Finland
Contributors: Hassan, S. S., Huttunen, H., Niemi, J., Tohka, J.
Number of pages: 8
Pages: 52-59
Publication date: 1 Dec 2019
Peer-reviewed: Yes

Publication information

Journal: Pattern Recognition Letters
Volume: 128
ISSN (Print): 0167-8655
Ratings: 
  • Scopus rating (2019): CiteScore 6.3 SJR 0.848 SNIP 2.021
Original language: English
ASJC Scopus subject areas: Software, Signal Processing, Computer Vision and Pattern Recognition, Artificial Intelligence
Keywords: Bayesian error estimation, Classification, Receiver operating characteristic curve

Bibliographical note

EXT="Tohka, Jussi"

Source: Scopus
Source ID: 85071016385

Research output: Contribution to journalArticleScientificpeer-review

Generalization of the K-SVD algorithm for minimization of β-divergence

In this paper, we propose, describe, and test a modification of the K-SVD algorithm. Given a set of training data, the proposed algorithm computes an overcomplete dictionary by minimizing the β-divergence (β>=1) between the data and its representation as linear combinations of atoms of the dictionary, under strict sparsity restrictions. For the special case β=2, the proposed algorithm minimizes the Frobenius norm and, therefore, for β=2 the proposed algorithm is equivalent to the original K-SVD algorithm. We describe the modifications needed and discuss the possible shortcomings of the new algorithm. The algorithm is tested with random matrices and with an example based on speech separation.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Computing Sciences, Universitat Politècnica de València
Contributors: Garcia-Molla, V. M., San Juan, P., Virtanen, T., Vidal, A. M., Alonso, P.
Number of pages: 7
Pages: 47-53
Publication date: 1 Sep 2019
Peer-reviewed: Yes

Publication information

Journal: Digital Signal Processing: A Review Journal
Volume: 92
ISSN (Print): 1051-2004
Ratings: 
  • Scopus rating (2019): CiteScore 5.5 SJR 0.659 SNIP 1.558
Original language: English
ASJC Scopus subject areas: Signal Processing, Electrical and Electronic Engineering
Keywords: Beta-divergence, K-SVD, Matching pursuit algorithms, NMF, Nonnegative K-SVD
Source: Scopus
Source ID: 85065411279

Research output: Contribution to journalArticleScientificpeer-review

An approval of MPPT based on pv cell’s simplified equivalent circuit during fast-shading conditions

The partial shading conditions significantly affect the functionality of solar power plants despite the presence of multiple maximum power point tracking systems. The primary cause of this problem is the presence of local maxima in the power–current and/or power–voltage characteristic curves that restrict the functionality of the conventional maximum power point tracking systems. The present article proposes a modified algorithm based on the simplified equivalent circuit of solar cells to improve the functionality of traditional maximum power point tracking systems. This algorithm provides a method for regularly monitoring the photo-current of each solar module. The upper and lower boundaries of the regulating parameter such as current or voltage are decided very precisely, which is helpful to find the location of the global maximum. During a sequential search, the control system accurately determines the lower and upper boundaries of the global maximum. Simultaneously, the maximum power point tracking system increases the photovoltaic current up to one of these boundaries and applies one of the conventional algorithms. Additionally, the control system regularly monitors the photovoltaic characteristics and changes the limits of regulating parameter concerning any change in global maximum location. This proposed method is fast and precise to locate the global maximum boundaries and to track global maximum even under fast-changing partial shading conditions. The improved performance and overall efficiency are validated by simulation study for variable solar irradiance.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Automation Technology and Mechanical Engineering, Ariel University Center of Samaria
Contributors: Rajput, S., Averbukh, M., Yahalom, A., Minav, T.
Number of pages: 14
Publication date: 1 Sep 2019
Peer-reviewed: Yes

Publication information

Journal: Electronics (Switzerland)
Volume: 8
Issue number: 9
Article number: 1060
ISSN (Print): 2079-9292
Ratings: 
  • Scopus rating (2019): CiteScore 1.9 SJR 0.303 SNIP 1.088
Original language: English
ASJC Scopus subject areas: Control and Systems Engineering, Signal Processing, Hardware and Architecture, Computer Networks and Communications, Electrical and Electronic Engineering
Keywords: Equivalent circuit, Global maximum, Maximum power point tracking, Partial shading, Photovoltaic system, Solar module
Electronic versions: 
Source: Scopus
Source ID: 85075081647

Research output: Contribution to journalArticleScientificpeer-review

Performance analysis of single-query 6-DoF camera pose estimation in self-driving setups

In this work, we consider the problem of single-query 6-DoF camera pose estimation, i.e. estimating the position and orientation of a camera by using reference images and a point cloud. We perform a systematic comparison of three state-of-the-art strategies for 6-DoF camera pose estimation: feature-based, photometric-based and mutual-information-based approaches. Two standard datasets with self-driving setups are used for experiments, and the performance of the studied methods is evaluated in terms of success rate, translation error and maximum orientation error. Building on the analysis of the results, we evaluate a hybrid approach that combines feature-based and mutual-information-based pose estimation methods to benefit from their complementary properties for pose estimation. Experiments show that (1) in cases with large appearance change between query and reference, the hybrid approach outperforms feature-based and mutual-information-based approaches by an average increment of 9.4% and 8.7% in the success rate, respectively; (2) in cases where query and reference images are captured at similar imaging conditions, the hybrid approach performs similarly as the feature-based approach, but outperforms both photometric-based and mutual-information-based approaches with a clear margin; (3) the feature-based approach is consistently more accurate than mutual-information-based and photometric-based approaches when at least 4 consistent matching points are found between the query and reference images.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Computing Sciences, Universidad Industrial de Santander, Czech Technical University in Prague
Contributors: Fu, J., Pertuz, S., Matas, J., Kämäräinen, J.
Pages: 58-73
Publication date: Sep 2019
Peer-reviewed: Yes

Publication information

Journal: Computer Vision and Image Understanding
Volume: 186
ISSN (Print): 1077-3142
Ratings: 
  • Scopus rating (2019): CiteScore 8.7 SJR 1.453 SNIP 2.255
Original language: English
ASJC Scopus subject areas: Software, Signal Processing, Computer Vision and Pattern Recognition
Keywords: 3D point cloud, Camera pose estimation, Hybrid method, Mutual information, Photometric matching, Self driving car

Bibliographical note

EXT="Matas, Jiri"

Source: Scopus
Source ID: 85067195521

Research output: Contribution to journalArticleScientificpeer-review

Design and implementation of a multi-sensor newborn EEG seizure and background model with inter-channel field characterization

This paper presents a novel multi-sensor non-stationary EEG model; it is obtained by combining state of the art mono-sensor newborn EEG simulators, a multilayer newborn head model comprised of four homogeneous concentric spheres, a multi-sensor propagation scheme based on array processing and optical dispersion to calculate inter-channel attenuation and delay, and lastly, a multi-variable optimization paradigm using particle swarm optimization and Monte-Carlo simulations to validate the model for optimal conditions. Multi-sensor EEG of 7 newborns, comprised of seizure and background epochs, are analyzed using time-space, time-frequency, power maps and multi-sensor causality techniques. The outcomes of these methods are validated by medical insights and serve as a backbone for any assumptions and as performance benchmarks for the model to be evaluated against. The results obtained with the developed model show 85.7% averaged time-frequency correlation (which is the selected measure for similarity with real EEG)with 5.9% standard deviation, and the averaged error obtained is 34.6% with 8% standard deviation. The resulting performances indicate that the proposed model provides a suitable matching fit with real EEG in terms of their probability density function, inter-sensor attenuation and translation, and multi-sensor causality. They also demonstrate the model flexibility to generate new unseen samples by utilizing user-defined parameters, making it suitable for other relevant applications.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Computing Sciences, Qatar University, University of Queensland
Contributors: Al-Sa'd, M. F., Boashash, B.
Number of pages: 29
Pages: 71-99
Publication date: 1 Jul 2019
Peer-reviewed: Yes

Publication information

Journal: Digital Signal Processing: A Review Journal
Volume: 90
ISSN (Print): 1051-2004
Ratings: 
  • Scopus rating (2019): CiteScore 5.5 SJR 0.659 SNIP 1.558
Original language: English
ASJC Scopus subject areas: Signal Processing, Electrical and Electronic Engineering
Keywords: EEG analysis, Multi-channel EEG, Multi-sensor propagation, Time-frequency processing, Time-space analysis
Source: Scopus
Source ID: 85065143207

Research output: Contribution to journalArticleScientificpeer-review

Socially inspired relaying and proactive mode selection in mmWave vehicular communications

As the Internet of Vehicles matures and acquires its social flavor, novel wireless connectivity enablers are being demanded for reliable data transfer in high-rate applications. The recently ratified New Radio communications technology operates in millimeter-wave (mmWave) spectrum bands and offers sufficient capacity for bandwidth-hungry services. However, seamless operation over mmWave is difficult to maintain on the move, since such extremely high frequency radio links are susceptible to unexpected blockage by various obstacles, including vehicle bodies. As a result, proactive mode selection, that is, migration from infrastructure- to vehicle-based connections and back, is becoming vital to avoid blockage situations. Fortunately, the very social structure of interactions between the neighboring smart cars and their passengers may be leveraged to improve session continuity by relaying data via proximate vehicles. This paper conceptualizes the socially inspired relaying scenarios, conducts underlying mathematical analysis, continues with a detailed 3-D modeling to facilitate proactive mode selection, and concludes by discussing a practical prototype of a vehicular mmWave platform.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Electrical Engineering, University of California, Los Angeles
Contributors: Moltchanov, D., Kovalchukov, R., Gerasimenko, M., Andreev, S., Koucheryavy, Y., Gerla, M.
Number of pages: 12
Pages: 5172-5183
Publication date: 1 Jun 2019
Peer-reviewed: Yes

Publication information

Journal: IEEE Internet of Things Journal
Volume: 6
Issue number: 3
ISSN (Print): 2327-4662
Ratings: 
  • Scopus rating (2019): CiteScore 12.6 SJR 2.607 SNIP 4.11
Original language: English
ASJC Scopus subject areas: Signal Processing, Information Systems, Hardware and Architecture, Computer Science Applications, Computer Networks and Communications
Keywords: Internet of Things, Millimeter wave (mmWave) communication, Social network services, Vehicular ad hoc networks
Electronic versions: 
Source: Scopus
Source ID: 85067875266

Research output: Contribution to journalArticleScientificpeer-review

Deep Learning for Audio Signal Processing

Given the recent surge in developments of deep learning, this paper provides a review of the state-of-the-art deep learning techniques for audio signal processing. Speech, music, and environmental sound processing are considered side-by-side, in order to point out similarities and differences between the domains, highlighting general methods, problems, key references, and potential for cross fertilization between areas. The dominant feature representations (in particular, log-mel spectra and raw waveform) and deep learning models are reviewed, including convolutional neural networks, variants of the long short-term memory architecture, as well as more audio-specific neural network models. Subsequently, prominent deep learning application areas are covered, i.e., audio recognition (automatic speech recognition, music information retrieval, environmental sound detection, localization and tracking) and synthesis and transformation (source separation, audio enhancement, generative models for speech, sound, and music synthesis). Finally, key issues and future questions regarding deep learning applied to audio signal processing are identified.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Computing Sciences, Aalborg University, Google Inc, University of Toulon, Austrian Research Institute for Artificial Intelligence
Contributors: Purwins, H., Li, B., Virtanen, T., Schlüter, J., Chang, S. Y., Sainath, T.
Number of pages: 14
Pages: 206-219
Publication date: 1 May 2019
Peer-reviewed: Yes

Publication information

Journal: IEEE Journal on Selected Topics in Signal Processing
Volume: 13
Issue number: 2
ISSN (Print): 1932-4553
Ratings: 
  • Scopus rating (2019): CiteScore 14.8 SJR 2.202 SNIP 3.123
Original language: English
ASJC Scopus subject areas: Signal Processing, Electrical and Electronic Engineering
Keywords: audio enhancement, automatic speech recognition, connectionist temporal memory, Deep learning, environmental sounds, music information retrieval, source separation
Source: Scopus
Source ID: 85065962111

Research output: Contribution to journalArticleScientificpeer-review

Convolutional low-resolution fine-grained classification

Successful fine-grained image classification methods learn subtle details between visually similar (sub-)classes, but the problem becomes significantly more challenging if the details are missing due to low resolution. Encouraged by the recent success of Convolutional Neural Network (CNN) architectures in image classification, we propose a novel resolution-aware deep model which combines convolutional image super-resolution and convolutional fine-grained classification into a single model in an end-to-end manner. Extensive experiments on multiple benchmarks demonstrate that the proposed model consistently performs better than conventional convolutional networks on classifying fine-grained object classes in low-resolution images.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Signal Processing, Research group: Vision
Contributors: Cai, D., Chen, K., Qian, Y., Kämäräinen, J.
Pages: 166-171
Publication date: Mar 2019
Peer-reviewed: Yes
Early online date: 2017

Publication information

Journal: Pattern Recognition Letters
Volume: 119
ISSN (Print): 0167-8655
Ratings: 
  • Scopus rating (2019): CiteScore 6.3 SJR 0.848 SNIP 2.021
Original language: English
ASJC Scopus subject areas: Software, Signal Processing, Computer Vision and Pattern Recognition, Artificial Intelligence
Keywords: Deep learning, Fine-grained image classification, Super resolution convoluational neural networks
Source: Scopus
Source ID: 85032974725

Research output: Contribution to journalArticleScientificpeer-review

ALMARVI System Solution for Image and Video Processing in Healthcare, Surveillance and Mobile Applications

ALMARVI is a collaborative European research project funded by Artemis involving 16 industrial as well as academic partners across 4 countries, working together to address various computational challenges in image and video processing in 3 application domains: healthcare, surveillance and mobile. This paper is an editorial for a special issue discussing the integrated system created by the partners to serve as a cross-domain solution for the project. The paper also introduces the partner articles published in this special issue to discuss the various technological developments achieved within ALMARVI spanning all system layers, from hardware to applications. We illustrate the challenges faced within the project based on use cases from the three targeted application domains, and how these can address the 4 main project objectives addressing 4 challenges faced by high performance image and video processing systems: massive data rate, low power consumption, composability and robustness. We present a system stack composed of algorithms, design frameworks and platforms as a solution to these challenges. Finally, the use cases from the three different application domains are mapped on the system stack solution and are evaluated based on their performance for each of the 4 ALMARVI objectives.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Pervasive Computing, Delft University of Technology, Philips Healthcare Nederland
Contributors: Al-Ars, Z., van der Vlugt, S., Jääskeläinen, P., van der Linden, F.
Pages: 1-7
Publication date: Jan 2019
Peer-reviewed: Yes
Early online date: 2018

Publication information

Journal: Journal of Signal Processing Systems
Volume: 91
Issue number: 1
ISSN (Print): 1939-8018
Ratings: 
  • Scopus rating (2019): CiteScore 2.4 SJR 0.298 SNIP 0.833
Original language: English
ASJC Scopus subject areas: Control and Systems Engineering, Theoretical Computer Science, Signal Processing, Information Systems, Modelling and Simulation, Hardware and Architecture
Source: Scopus
Source ID: 85057058836

Research output: Contribution to journalArticleScientificpeer-review

Video coding of dynamic 3D point cloud data

Due to the increased popularity of augmented (AR) and virtual (VR) reality experiences, the interest in representing the real world in an immersive fashion has never been higher. Distributing such representations enables users all over the world to freely navigate in never seen before media experiences. Unfortunately, such representations require a large amount of data, not feasible for transmission on today's networks. Thus, efficient compression technologies are in high demand. This paper proposes an approach to compress 3D video data utilizing 2D video coding technology. The proposed solution was developed to address the needs of "tele-immersive" applications, such as VR, AR, or mixed reality with "Six Degrees of Freedom" capabilities. Volumetric video data is projected on 2D image planes and compressed using standard 2D video coding solutions. A key benefit of this approach is its compatibility with readily available 2D video coding infrastructure. Furthermore, objective and subjective evaluation shows significant improvement in coding efficiency over reference technology. The proposed solution was contributed and evaluated in international standardization. Although it is was not selected as the winning proposal, as very similar solution has been selected developed since then.

General information

Publication status: E-pub ahead of print
MoE publication type: A1 Journal article-refereed
Organisations: Computing Sciences, Nokia Technologies
Contributors: Schwarz, S., Sheikhipour, N., Fakour Sevom, V., Hannuksela, M. M.
Number of pages: 12
Publication date: 2019
Peer-reviewed: Yes

Publication information

Journal: APSIPA Transactions on Signal and Information Processing
Article number: e31
ISSN (Print): 2048-7703
Ratings: 
  • Scopus rating (2019): CiteScore 2.1 SJR 0.251 SNIP 0.655
Original language: English
ASJC Scopus subject areas: Signal Processing, Information Systems
Keywords: AR, Immersive media, Point cloud coding, Volumetric video
Source: Scopus
Source ID: 85076929574

Research output: Contribution to journalArticleScientificpeer-review

Digital Predistortion for 5G Small Cell: GPU Implementation and RF Measurements

In this paper, we present a high data rate implementation of a digital predistortion (DPD) algorithm on a modern mobile multicore CPU containing an on-chip GPU. The proposed implementation is capable of running in real-time, thanks to the execution of the predistortion stage inside the GPU, and the execution of the learning stage on a separate CPU core. This configuration, combined with the low complexity DPD design, allows for more than 400 Msamples/s sample rates. This is sufficient for satisfying 5G new radio (NR) base station radio transmission specifications in the sub-6 GHz bands, where signal bandwidths up to 100 MHz are specified. The linearization performance is validated with RF measurements on two base station power amplifiers at 3.7 GHz, showing that the 5G NR downlink emission requirements are satisfied.

General information

Publication status: E-pub ahead of print
MoE publication type: A1 Journal article-refereed
Organisations: Electrical Engineering, Computing Sciences, Research area: Computer engineering, Research group: Wireless Communications and Positioning, University of Vaasa (UVA), Tampere University
Contributors: Pascual Campo, P., Lampu, V., Meirhaeghe, A., Boutellier, J., Anttila, L., Valkama, M.
Number of pages: 12
Publication date: 2019
Peer-reviewed: Yes

Publication information

Journal: Journal of Signal Processing Systems
ISSN (Print): 1939-8018
Ratings: 
  • Scopus rating (2019): CiteScore 2.4 SJR 0.298 SNIP 0.833
Original language: English
ASJC Scopus subject areas: Control and Systems Engineering, Theoretical Computer Science, Signal Processing, Information Systems, Modelling and Simulation, Hardware and Architecture
Keywords: 5G, Digital predistortion (DPD), GPU, High data rate, Real-time

Bibliographical note

INT=comp,"Meirhaeghe, Alexandre"

Source: Scopus
Source ID: 85077054281

Research output: Contribution to journalArticleScientificpeer-review

Cascade of Boolean detector combinations

This paper considers a scenario when we have multiple pre-trained detectors for detecting an event and a small dataset for training a combined detection system. We build the combined detector as a Boolean function of thresholded detector scores and implement it as a binary classification cascade. The cascade structure is computationally efficient by providing the possibility to early termination. For the proposed Boolean combination function, the computational load of classification is reduced whenever the function becomes determinate before all the component detectors have been utilized. We also propose an algorithm, which selects all the needed thresholds for the component detectors within the proposed Boolean combination. We present results on two audio-visual datasets, which prove the efficiency of the proposed combination framework. We achieve state-of-the-art accuracy with substantially reduced computation time in laughter detection task, and our algorithm finds better thresholds for the component detectors within the Boolean combination than the other algorithms found in the literature.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Signal Processing
Contributors: Mahkonen, K., Virtanen, T., Kämäräinen, J.
Publication date: Dec 2018
Peer-reviewed: Yes

Publication information

Journal: Eurasip Journal on Image and Video Processing
Volume: 2018
Article number: 61
ISSN (Print): 1687-5176
Ratings: 
  • Scopus rating (2018): CiteScore 2.2 SJR 0.342 SNIP 1.086
Original language: English
ASJC Scopus subject areas: Signal Processing, Information Systems, Electrical and Electronic Engineering
Keywords: Binary classification, Boolean combination, Classification cascade
Source: Scopus
Source ID: 85050598957

Research output: Contribution to journalArticleScientificpeer-review

Toward Efficient Execution of RVC-CAL Dataflow Programs on Multicore Platforms

The increasing number of cores in System on Chips (SoC) has introduced challenges in software parallelization. As an answer to this, the dataflow programming model offers a concurrent and reusability promoting approach for describing applications. In this work, a runtime for executing Dataflow Process Networks (DPN) on multicore platforms is proposed. The main difference between this work and existing methods is letting the operating system perform Central processing unit (CPU) load-balancing freely, instead of limiting thread migration between processing cores through CPU affinity. The proposed runtime is benchmarked on desktop and server multicore platforms using five different applications from video coding and telecommunication domains. The results show that the proposed method offers significant improvements over the state-of-art, in terms of performance and reliability.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Pervasive Computing, Research area: Computer engineering, Univ of Oulu
Contributors: Hautala, I., Boutellier, J., Nyländen, T., Silvén, O.
Number of pages: 11
Pages: 1507-1517
Publication date: Nov 2018
Peer-reviewed: Yes
Early online date: 9 Feb 2018

Publication information

Journal: Journal of Signal Processing Systems
Volume: 90
Issue number: 11
ISSN (Print): 1939-8018
Ratings: 
  • Scopus rating (2018): CiteScore 1.7 SJR 0.203 SNIP 0.61
Original language: English
ASJC Scopus subject areas: Control and Systems Engineering, Theoretical Computer Science, Signal Processing, Information Systems, Modelling and Simulation, Hardware and Architecture
Keywords: Dataflow Process Networks, Multicore, Orcc, RVC-CAL
Source: Scopus
Source ID: 85041532591

Research output: Contribution to journalArticleScientificpeer-review

Skew-t Filter and Smoother with Improved Covariance Matrix Approximation

Filtering and smoothing algorithms for linear discrete-time state-space models with skew-t-distributed measurement noise are proposed. The algorithms use a variational Bayes based posterior approximation with coupled location and skewness variables to reduce the error caused by the variational approximation. Although the variational update is done suboptimally using an expectation propagation algorithm, our simulations show that the proposed method gives a more accurate approximation of the posterior covariance matrix than an earlier proposed variational algorithm. Consequently, the novel filter and smoother outperform the earlier proposed robust filter and smoother and other existing low-complexity alternatives in accuracy and speed. We present both simulations and tests based on real-world navigation data, in particular GPS data in an urban area, to demonstrate the performance of the novel methods. Moreover, the extension of the proposed algorithms to cover the case where the distribution of the measurement noise is multivariate skew-t is outlined. Finally, the paper presents a study of theoretical performance bounds for the proposed algorithms.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Automation and Hydraulic Engineering, Linkiping University, Linki-ping University
Contributors: Nurminen, H., Ardeshiri, T., Piche, R., Gustafsson, F.
Pages: 5618-5633
Publication date: Nov 2018
Peer-reviewed: Yes
Early online date: 13 Aug 2018

Publication information

Journal: IEEE Transactions on Signal Processing
Volume: 66
Issue number: 21
ISSN (Print): 1053-587X
Ratings: 
  • Scopus rating (2018): CiteScore 9.8 SJR 1.477 SNIP 2.632
Original language: English
ASJC Scopus subject areas: Signal Processing, Electrical and Electronic Engineering
Keywords: Approximation algorithms, Biological system modeling, Covariance matrices, Cramer-Rao lower bound, expectation propagation, Gaussian distribution, Kalman filter, Noise measurement, robust filtering, RTS smoother, Signal processing algorithms, skew t, Smoothing methods, t-distribution, truncated normal distribution, variational Bayes
Electronic versions: 
Source: Scopus
Source ID: 85051630249

Research output: Contribution to journalArticleScientificpeer-review

Deep Learning Case Study for Automatic Bird Identification

An automatic bird identification system is required for offshore wind farms in Finland. Indubitably, a radar is the obvious choice to detect flying birds, but external information is required for actual identification. We applied visual camera images as external data. The proposed system for automatic bird identification consists of a radar, a motorized video head and a single-lens reflex camera with a telephoto lens. A convolutional neural network trained with a deep learning algorithm is applied to the image classification. We also propose a data augmentation method in which images are rotated and converted in accordance with the desired color temperatures. The final identification is based on a fusion of parameters provided by the radar and the predictions of the image classifier. The sensitivity of this proposed system, on a dataset containing 9312 manually taken original images resulting in 2.44 × 106 augmented data set, is 0.9463 as an image classifier. The area under receiver operating characteristic curve for two key bird species is 0.9993 (the White-tailed Eagle) and 0.9496 (The Lesser Black-backed Gull), respectively. We proposed a novel system for automatic bird identification as a real world application. We demonstrated that our data augmentation method is suitable for image classification problem and it significantly increases the performance of the classifier.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Signal Processing, Research group: Data-analytics and Optimization, Mathematics
Contributors: Niemi, J., Tanttu, J.
Number of pages: 15
Publication date: 29 Oct 2018
Peer-reviewed: Yes

Publication information

Journal: Applied Sciences (Switzerland)
Volume: 8
Issue number: 11
Article number: 2089
ISSN (Print): 2076-3417
Ratings: 
  • Scopus rating (2018): SJR 0.379 SNIP 1.029
Original language: English
ASJC Scopus subject areas: Artificial Intelligence, Signal Processing, Computer Vision and Pattern Recognition
Keywords: Machine learning, Deep learning, Convolutional neural networks, Classification, data augmentation, intelligent surveillance systems

Research output: Contribution to journalArticleScientificpeer-review

Benchmark database for fine-grained image classification of benthic macroinvertebrates

Managing the water quality of freshwaters is a crucial task worldwide. One of the most used methods to biomonitor water quality is to sample benthic macroinvertebrate communities, in particular to examine the presence and proportion of certain species. This paper presents a benchmark database for automatic visual classification methods to evaluate their ability for distinguishing visually similar categories of aquatic macroinvertebrate taxa. We make publicly available a new database, containing 64 types of freshwater macroinvertebrates, ranging in number of images per category from 7 to 577. The database is divided into three datasets, varying in number of categories (64, 29, and 9 categories). Furthermore, in order to accomplish a baseline evaluation performance, we present the classification results of Convolutional Neural Networks (CNNs) that are widely used for deep learning tasks in large databases. Besides CNNs, we experimented with several other well-known classification methods using deep features extracted from the data.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Signal Processing, Qatar University, University of Jyvaskyla, Finnish Environment Institute
Contributors: Raitoharju, J., Riabchenko, E., Ahmad, I., Iosifidis, A., Gabbouj, M., Kiranyaz, S., Tirronen, V., Ärje, J., Kärkkäinen, S., Meissner, K.
Number of pages: 11
Pages: 73-83
Publication date: 1 Oct 2018
Peer-reviewed: Yes

Publication information

Journal: Image and Vision Computing
Volume: 78
ISSN (Print): 0262-8856
Ratings: 
  • Scopus rating (2018): CiteScore 4.9 SJR 0.633 SNIP 1.655
Original language: English
ASJC Scopus subject areas: Signal Processing, Computer Vision and Pattern Recognition
Keywords: Benthic macroinvertebrates, Biomonitoring, Convolutional Neural Networks, Deep learning, Fine-grained classification
Source: Scopus
Source ID: 85052861257

Research output: Contribution to journalArticleScientificpeer-review

Nonlocality-Reinforced Convolutional Neural Networks for Image Denoising

We introduce a paradigm for nonlocal sparsity reinforced deep convolutional neural network denoising. It is a combination of a local multiscale denoising by a convolutional neural network (CNN) based denoiser and a nonlocal denoising based on a nonlocal filter (NLF), exploiting the mutual similarities between groups of patches. CNN models are leveraged with noise levels that progressively decrease at every iteration of our framework, while their output is regularized by a nonlocal prior implicit within the NLF. Unlike complicated neural networks that embed the nonlocality prior within the layers of the network, our framework is modular, and it uses standard pretrained CNNs together with standard nonlocal filters. An instance of the proposed framework, called NN3D, is evaluated over large grayscale image datasets showing state-of-the-art performance.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Signal Processing, Noiseless Imaging Ltd
Contributors: Cruz, C., Foi, A., Katkovnik, V., Egiazarian, K.
Number of pages: 5
Pages: 1216-1220
Publication date: 1 Aug 2018
Peer-reviewed: Yes

Publication information

Journal: IEEE Signal Processing Letters
Volume: 25
Issue number: 8
ISSN (Print): 1070-9908
Ratings: 
  • Scopus rating (2018): CiteScore 7 SJR 0.785 SNIP 1.983
Original language: English
ASJC Scopus subject areas: Signal Processing, Electrical and Electronic Engineering, Applied Mathematics
Keywords: BM3D, convolutional neural network, image denoising, nonlocal filters
Source: Scopus
Source ID: 85049097929

Research output: Contribution to journalArticleScientificpeer-review

Summarization of User-Generated Sports Video by Using Deep Action Recognition Features

Automatically generating a summary of sports video poses the challenge of detecting interesting moments, or highlights, of a game. Traditional sports video summarization methods leverage editing conventions of broadcast sports video that facilitate the extraction of high-level semantics. However, user-generated videos are not edited, and thus traditional methods are not suitable to generate a summary. In order to solve this problem, this work proposes a novel video summarization method that uses players' actions as a cue to determine the highlights of the original video. A deep neural network-based approach is used to extract two types of action-related features and to classify video segments into interesting or uninteresting parts. The proposed method can be applied to any sports in which games consist of a succession of actions. Especially, this work considers the case of Kendo (Japanese fencing) as an example of a sport to evaluate the proposed method. The method is trained using Kendo videos with ground truth labels that indicate the video highlights. The labels are provided by annotators possessing different experience with respect to Kendo to demonstrate how the proposed method adapts to different needs. The performance of the proposed method is compared with several combinations of different features, and the results show that it outperforms previous summarization methods.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Signal Processing, University of Tokyo, Osaka University, Graduate School of Information Science, Univ of Oulu
Contributors: Tejero-de-Pablos, A., Nakashima, Y., Sato, T., Yokoya, N., Linna, M., Rahtu, E.
Pages: 2000-2011
Publication date: Aug 2018
Peer-reviewed: Yes
Early online date: 15 Jan 2018

Publication information

Journal: IEEE Transactions on Multimedia
Volume: 20
Issue number: 8
ISSN (Print): 1520-9210
Ratings: 
  • Scopus rating (2018): CiteScore 9.3 SJR 1.222 SNIP 3.016
Original language: English
ASJC Scopus subject areas: Signal Processing, Media Technology, Computer Science Applications, Electrical and Electronic Engineering
Keywords: 3D convolutional neural networks, action recognition, Cameras, deep learning, Feature extraction, Games, Hidden Markov models, long short-term memory, Semantics, Sports video summarization, Three-dimensional displays, user-generated video
Source: Scopus
Source ID: 85041689127

Research output: Contribution to journalArticleScientificpeer-review

Stabilization to trajectories for parabolic equations

Both internal and boundary feedback exponential stabilization to trajectories for semilinear parabolic equations in a given bounded domain are addressed. The values of the controls are linear combinations of a finite number of actuators which are supported in a small region. A condition on the family of actuators is given which guarantees the local stabilizability of the control system. It is shown that a linearization-based Riccati feedback stabilizing controller can be constructed. The results of numerical simulations are presented and discussed.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Mathematics, Johann Radon Institute for Computational and Applied Mathematics
Contributors: Phan, D., Rodrigues, S. S.
Publication date: 1 Jun 2018
Peer-reviewed: Yes

Publication information

Journal: Mathematics of Control, Signals, and Systems
Volume: 30
Issue number: 2
Article number: 11
ISSN (Print): 0932-4194
Ratings: 
  • Scopus rating (2018): CiteScore 1.4 SJR 0.386 SNIP 0.701
Original language: English
ASJC Scopus subject areas: Control and Systems Engineering, Signal Processing, Control and Optimization, Applied Mathematics
Keywords: Feedback stabilization to trajectories, Semilinear parabolic equations
Source: Scopus
Source ID: 85050079985

Research output: Contribution to journalArticleScientificpeer-review

Delay-Accuracy Trade-off in Opportunistic Time-of-Arrival Localization

While designing a positioning network, the localization performance is traditionally the main concern. However, collection of measurements together with channel access methods require a nonzero time, causing a delay experienced by network nodes. This fact is usually neglected in positioning-related literature. In terms of the delay-accuracy trade-off, broadcast schemes have an advantage over unicast, provided nodes can be properly synchronized. In this letter, we analyze the delay-accuracy trade-off, for localization schemes in which the position estimates are obtained based on broadcasted ranging signals. We find that for dense networks, the trade-off is the same for cooperative and noncooperative networks, and cannot exceed a certain threshold value.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Research group: System-on-Chip for GNSS, Wireless Communications and Cyber-Physical Embedded Computing, Electronics and Communications Engineering, Research group: Wireless Communications and Positioning, Research group: System-on-Chip for GNSS, Wireless Communications and Cyber-Physical Embedded Computing, Chalmers University of Technology
Contributors: Daniel, O., Wymeersch, H., Nurmi, J.
Pages: 763-767
Publication date: Jun 2018
Peer-reviewed: Yes
Early online date: 14 Apr 2018

Publication information

Journal: IEEE Signal Processing Letters
Volume: 25
Issue number: 6
ISSN (Print): 1070-9908
Ratings: 
  • Scopus rating (2018): CiteScore 7 SJR 0.785 SNIP 1.983
Original language: English
ASJC Scopus subject areas: Signal Processing, Electrical and Electronic Engineering

Research output: Contribution to journalArticleScientificpeer-review

Digital Predistortion for Hybrid MIMO Transmitters

This article investigates digital predistortion (DPD) linearization of hybrid beamforming large-scale antenna transmitters. We propose a novel DPD processing and learning technique for an antenna sub-array, which utilizes a combined signal of the individual power amplifier (PA) outputs in conjunction with a decorrelation-based learning rule. In effect, the proposed approach results in minimizing the nonlinear distortions in the direction of the intended receiver. This feature is highly desirable, since emissions in other directions are naturally weak due to beamforming. The proposed parameter learning technique requires only a single observation receiver, and therefore supports simple hardware implementation. It is also shown to clearly outperform the current state-of-the-art technique which utilizes only a single PA for learning. Analysis of the feedback network amplitude and phase imbalances reveals that the technique is robust even to high levels of such imbalances. Finally, we also show that the array system out-of-band emissions are well-behaving in all spatial directions, and essentially below those of the corresponding single-antenna transmitter, due to the combined effects of the DPD and beamforming.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Electronics and Communications Engineering, Research group: Wireless Communications and Positioning, Lund University
Contributors: Abdelaziz, M., Anttila, L., Brihuega, A., Tufvesson, F., Valkama, M.
Pages: 445-454
Publication date: Jun 2018
Peer-reviewed: Yes
Early online date: 7 Apr 2018

Publication information

Journal: IEEE Journal on Selected Topics in Signal Processing
Volume: 12
Issue number: 3
ISSN (Print): 1932-4553
Ratings: 
  • Scopus rating (2018): CiteScore 10.4 SJR 1.404 SNIP 2.657
Original language: English
ASJC Scopus subject areas: Signal Processing, Electrical and Electronic Engineering
Keywords: 5G, digital predistortion, hybrid beamforming, large-array transmitters, out-of-band emissions, power amplifiers
Source: Scopus
Source ID: 85045212003

Research output: Contribution to journalArticleScientificpeer-review

Analysis of common rail pressure signal of dual-fuel large industrial engine for identification of injection duration of pilot diesel injectors

In this paper, we address the problem of identification of injection duration of common rail (CR) diesel pilot injectors of dual-fuel engines. In these pilot injectors, the injected volume is small and the repeatability of injections and identification of drifts of injectors are important factors, which need to be taken into account in order to achieve good repeatability (shot-to-shot with every cylinder) and therefore a well-balanced engine and furthermore reduced overall wear. This information can then be used for calibration and diagnostics purposes to guarantee engine longevity facilitated by consistent operating conditions throughout the life of the unit. A diagnostics method based on analysis of CR pressure with experimental results is presented in this paper. Using the developed method, the relative duration of injection events can be identified for multiple injectors. We use the phenomenon of drop in rail pressure due to an injection event as a feature of the injection process. The method is based on filtered CR pressure data during and after the injection event. First, the pressure signal during injection is extracted after control of each injection event. After that, the signal is normalized and filtered. Then a derivative of the filtered signal is calculated. Change in the derivative of the filtered signal larger than a predefined threshold indicates an injection event that can be detected and its relative duration can be identified. We present the experimental results and demonstrate the efficacy of the proposed methods using two different
types of pressure sensors. We are able to properly identify a change of ≥10 μs (2%, 500 μs) in injection time. This shows that the developed method detects drifts in injection duration and the magnitude of drift. This information can be used for adaptive control of injection duration, so that finally the injected fuel volume is the same as the original.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Automation and Hydraulic Engineering
Contributors: Krogerus, T., Hyvönen, M., Huhtala, K.
Pages: 1-9
Publication date: Mar 2018
Peer-reviewed: Yes
Early online date: 6 Dec 2017

Publication information

Journal: Fuel
Volume: 216
ISSN (Print): 0016-2361
Ratings: 
  • Scopus rating (2018): CiteScore 8.9 SJR 1.745 SNIP 2.041
Original language: English
ASJC Scopus subject areas: Mechanical Engineering, Signal Processing, Modelling and Simulation, Applied Mathematics
Keywords: Analysis , Dual-fuel engine , Diesel , Common rail , Injector , Rail pressure
Electronic versions: 
URLs: 

Research output: Contribution to journalArticleScientificpeer-review

Detection and Classification of Acoustic Scenes and Events: Outcome of the DCASE 2016 Challenge

Public evaluation campaigns and datasets promote active development in target research areas, allowing direct comparison of algorithms. The second edition of the challenge on Detection and Classification of Acoustic Scenes and Events (DCASE 2016) has offered such an opportunity for development of state-of-the-art methods, and succeeded in drawing together a large number of participants from academic and industrial backgrounds. In this paper, we report on the tasks and outcomes of the DCASE 2016 challenge. The challenge comprised four tasks: acoustic scene classification, sound event detection in synthetic audio, sound event detection in real-life audio, and domestic audio tagging. We present in detail each task and analyse the submitted systems in terms of design and performance. We observe the emergence of deep learning as the most popular classification method, replacing the traditional approaches based on Gaussian mixture models and support vector machines. By contrast, feature representations have not changed substantially throughout the years, as mel frequency-based representations predominate in all tasks. The datasets created for and used in DCASE 2016 are publicly available and are a valuable resource for further research.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Signal Processing, Research group: Audio research group - ARG, School of Mathematical Sciences, Ecole Centrale de Nantes, IRCCyN UMR CNRS 6597 1, University of Surrey
Contributors: Mesaros, A., Heittola, T., Benetos, E., Foster, P., Lagrange, M., Virtanen, T., Plumbley, M. D.
Pages: 379-393
Publication date: Feb 2018
Peer-reviewed: Yes
Early online date: 28 Nov 2017

Publication information

Journal: IEEE/ACM Transactions on Audio Speech and Language Processing
Volume: 26
Issue number: 2
ISSN (Print): 2329-9290
Ratings: 
  • Scopus rating (2018): CiteScore 6.9 SJR 1.045 SNIP 2.428
Original language: English
ASJC Scopus subject areas: Signal Processing, Media Technology, Instrumentation, Acoustics and Ultrasonics, Linguistics and Language, Electrical and Electronic Engineering, Speech and Hearing
Keywords: Acoustic scene classification, Acoustics, audio datasets, Event detection, Hidden Markov models, pattern recognition, sound event detection, Speech, Speech processing, Tagging
Electronic versions: 
Source: Scopus
Source ID: 85037645922

Research output: Contribution to journalArticleScientificpeer-review

Probabilistic saliency estimation

In this paper, we model the salient object detection problem under a probabilistic framework encoding the boundary connectivity saliency cue and smoothness constraints into an optimization problem. We show that this problem has a closed form global optimum solution, which estimates the salient object. We further show that along with the probabilistic framework, the proposed method also enjoys a wide range of interpretations, i.e. graph cut, diffusion maps and one-class classification. With an analysis according to these interpretations, we also find that our proposed method provides approximations to the global optimum to another criterion that integrates local/global contrast and large area saliency cues. The proposed unsupervised approach achieves mostly leading performance compared to the state-of-the-art unsupervised algorithms over a large set of salient object detection datasets including around 17k images for several evaluation metrics. Furthermore, the computational complexity of the proposed method is favorable/comparable to many state-of-the-art unsupervised techniques.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Signal Processing, Research group: Multimedia Research Group - MRG
Contributors: Aytekin, C., Iosifidis, A., Gabbouj, M.
Number of pages: 14
Pages: 359-372
Publication date: 2018
Peer-reviewed: Yes
Early online date: 20 Sep 2017

Publication information

Journal: Pattern Recognition
Volume: 74
ISSN (Print): 0031-3203
Ratings: 
  • Scopus rating (2018): CiteScore 10.4 SJR 1.363 SNIP 3.211
Original language: English
ASJC Scopus subject areas: Software, Signal Processing, Computer Vision and Pattern Recognition, Artificial Intelligence
Keywords: Diffusion maps, One-class classification, Probabilistic model, Saliency, Salient object detection, Spectral graph cut
Source: Scopus
Source ID: 85032271491

Research output: Contribution to journalArticleScientificpeer-review

Separation of Moving Sound Sources Using Multichannel NMF and Acoustic Tracking

In this paper we propose a method for separation of moving sound sources. The method is based on first tracking the sources and then estimation of source spectrograms using multichannel non-negative matrix factorization (NMF) and extracting the sources from the mixture by single-channel Wiener filtering. We propose a novel multichannel NMF model with time-varying mixing of the sources denoted by spatial covariance matrices (SCM) and provide update equations for optimizing model parameters minimizing squared Frobenius norm. The SCMs of the model are obtained based on estimated directions of arrival of tracked sources at each time frame. The evaluation is based on established objective separation criteria and using real recordings of two and three simultaneous moving sound sources. The compared methods include conventional beamforming and ideal ratio mask separation. The proposed method is shown to exceed the separation quality of other evaluated blind approaches according to all measured quantities. Additionally, we evaluate the method's susceptibility towards tracking errors by comparing the separation quality achieved using annotated ground truth source trajectories.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Signal Processing, Research group: Audio research group - ARG
Contributors: Nikunen, J., Diment, A., Virtanen, T.
Pages: 281-295
Publication date: 2018
Peer-reviewed: Yes
Early online date: 16 Nov 2017

Publication information

Journal: IEEE/ACM Transactions on Audio Speech and Language Processing
Volume: 26
Issue number: 2
ISSN (Print): 2329-9290
Ratings: 
  • Scopus rating (2018): CiteScore 6.9 SJR 1.045 SNIP 2.428
Original language: English
ASJC Scopus subject areas: Signal Processing, Media Technology, Instrumentation, Acoustics and Ultrasonics, Linguistics and Language, Electrical and Electronic Engineering, Speech and Hearing
Keywords: acoustic source tracking, Acoustics, Array signal processing, Direction-of-arrival estimation, Estimation, Mathematical model, microphone arrays, Microphones, moving sound sources, Sound source separation, Spectrogram, time-varying mixing model
Source: Scopus
Source ID: 85035748523

Research output: Contribution to journalArticleScientificpeer-review

Damped Posterior Linearization Filter

In this letter, we propose an iterative Kalman type algorithm based on posterior linearization. The proposed algorithm uses a nested loop structure to optimize the mean of the estimate in the inner loop and update the covariance, which is a computationally more expensive operation, only in the outer loop. The optimization of the mean update is done using a damped algorithm to avoid divergence. Our simulations show that the proposed algorithm is more accurate than existing iterative Kalman filters.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Automation and Hydraulic Engineering, Lab of Electrical and Automation, University of Liverpool
Contributors: Raitoharju, M., Svensson, L., Garcia-Fernandez, A. F., Piche, R.
Publication date: 2018
Peer-reviewed: Yes
Early online date: 13 Feb 2018

Publication information

Journal: IEEE Signal Processing Letters
Volume: 25
Issue number: 4
ISSN (Print): 1070-9908
Ratings: 
  • Scopus rating (2018): CiteScore 7 SJR 0.785 SNIP 1.983
Original language: English
ASJC Scopus subject areas: Signal Processing, Electrical and Electronic Engineering, Applied Mathematics
Keywords: Bayesian state estimation, Computational modeling, Convergence, Cost function, estimation, Kalman filters, Noise measurement, nonlinear, Signal processing algorithms
Electronic versions: 

Bibliographical note

EXT="Raitoharju, Matti"

Source: Scopus
Source ID: 85042110206

Research output: Contribution to journalArticleScientificpeer-review

Estimation and Mitigation of Channel Non-Reciprocity in Massive MIMO

Time-division duplex (TDD) based massive MIMO systems rely on the reciprocity of the wireless propagation channels when calculating the downlink precoders based on uplink pilots. However, the effective uplink and downlink channels incorporating the analog radio front-ends of the base station (BS) and user equipments (UEs) exhibit non-reciprocity due to non-identical behavior of the individual transmit and receive chains. When downlink precoder is not aware of such channel non-reciprocity (NRC), system performance can be significantly degraded due to NRC induced interference terms. In this work, we consider a general TDD-based massive MIMO system where frequency-response mismatches at both the BS and UEs, as well as the mutual coupling mismatch at the BS large-array system all coexist and induce channel NRC. Based on the NRC-impaired signal models, we first propose a novel iterative estimation method for acquiring both the BS and UE side NRC matrices and then also propose a novel NRC-aware downlink precoder design which utilizes the obtained estimates. Furthermore, an efficient pilot signaling scheme between the BS and UEs is introduced in order to facilitate executing the proposed estimation method and the NRC-aware precoding technique in practical systems. Comprehensive numerical results indicate substantially improved spectral efficiency performance when the proposed NRC estimation and NRC-aware precoding methods are adopted, compared to the existing state-of-the-art methods.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Electronics and Communications Engineering, Research group: Wireless Communications and Positioning
Contributors: Raeesi, O., Gokceoglu, A., Valkama, M.
Publication date: 2018
Peer-reviewed: Yes
Early online date: 10 Mar 2018

Publication information

Journal: IEEE Transactions on Signal Processing
Volume: 66
Issue number: 10
ISSN (Print): 1053-587X
Ratings: 
  • Scopus rating (2018): CiteScore 9.8 SJR 1.477 SNIP 2.632
Original language: English
ASJC Scopus subject areas: Signal Processing, Electrical and Electronic Engineering
Keywords: Beamforming, channel non-reciprocity, channel state information, frequency-response mismatch, linear precoding, massive MIMO, mutual coupling, time division duplexing (TDD)
Electronic versions: 
Source: Scopus
Source ID: 85043450743

Research output: Contribution to journalArticleScientificpeer-review

Multi-view predictive latent space learning

In unsupervised circumstances, multi-view learning seeks a shared latent representation by taking the consensus and complementary principles into account. However, most existing multi-view unsupervised learning approaches do not explicitly lay stress on the predictability of the latent space. In this paper, we propose a novel multi-view predictive latent space learning (MVP) model and apply it to multi-view clustering and unsupervised dimension reduction. The latent space is forced to be predictive by maximizing the correlation between the latent space and feature space of each view. By learning a multi-view graph with adaptive view-weight learning, MVP effectively combines the complementary information from multi-view data. Experimental results on benchmark datasets show that MVP outperforms the state-of-the-art multi-view clustering and unsupervised dimension reduction algorithms.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Signal Processing, Tianjin University
Contributors: Yuan, J., Gao, K., Zhu, P., Egiazarian, K.
Publication date: 2018
Peer-reviewed: Yes
Early online date: 2018

Publication information

Journal: Pattern Recognition Letters
ISSN (Print): 0167-8655
Ratings: 
  • Scopus rating (2018): CiteScore 5.8 SJR 0.662 SNIP 1.729
Original language: English
ASJC Scopus subject areas: Software, Signal Processing, Computer Vision and Pattern Recognition, Artificial Intelligence
Keywords: Multi-view learning, Predictive latent space learning, Unsupervised clustering, Unsupervised dimension reduction
Source: Scopus
Source ID: 85049094619

Research output: Contribution to journalArticleScientificpeer-review

Model-Based Dynamic Scheduling for Multicore Signal Processing

This paper presents a model-based design method and a corresponding new software tool, the HTGS Model-Based Engine (HMBE), for designing and implementing dataflow-based signal processing applications on multi-core architectures. HMBE provides complementary capabilities to HTGS (Hybrid Task Graph Scheduler), a recently-introduced software tool for implementing scalable workflows for high performance computing applications on compute nodes with high core counts and multiple GPUs. HMBE integrates model-based design approaches, founded on dataflow principles, with advanced design optimization techniques provided in HTGS. This integration contributes to (a) making the application of HTGS more systematic and less time consuming, (b) incorporating additional dataflow-based optimization capabilities with HTGS optimizations, and (c) automating significant parts of the HTGS-based design process using a principled approach. In this paper, we present HMBE with an emphasis on the model-based design approaches and the novel dynamic scheduling techniques that are developed as part of the tool. We demonstrate the utility of HMBE via two case studies: an image stitching application for large microscopy images and a background subtraction application for multispectral video streams.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Pervasive Computing, Research area: Computer engineering, University of Maryland, National Institute of Standards and Technology
Contributors: Wu, J., Blattner, T., Keyrouz, W., Bhattacharyya, S. S.
Number of pages: 14
Pages: 1-14
Publication date: 2018
Peer-reviewed: Yes
Early online date: 2018

Publication information

Journal: Journal of Signal Processing Systems
ISSN (Print): 1939-8018
Ratings: 
  • Scopus rating (2018): CiteScore 1.7 SJR 0.203 SNIP 0.61
Original language: English
ASJC Scopus subject areas: Control and Systems Engineering, Theoretical Computer Science, Signal Processing, Information Systems, Modelling and Simulation, Hardware and Architecture
Keywords: Dataflow, Memory management, Multicore platforms, Scheduling
Source: Scopus
Source ID: 85054798661

Research output: Contribution to journalArticleScientificpeer-review

Sparse approximations in complex domain based on BM3D modeling

In this paper the concept of sparsity for complex-valued variables is introduced in the following three types: directly in complex domain and for two real-valued pairs phase/amplitude and real/imaginary parts of complex variables. The nonlocal block-matching technique is used for sparsity implementation and filter design for each type of sparsity. These filters are complex domain generalizations of the Block Matching 3D collaborative (BM3D) filter based on the high-order singular value decomposition (HOSVD) in order to generate group-wise adaptive analysis/synthesis transforms. Complex domain denoising is developed and studied as a test-problem for comparison of the designed filters as well as the different types of sparsity modeling.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Signal Processing, Research group: Computational Imaging-CI
Contributors: Katkovnik, V., Ponomarenko, M., Egiazarian, K.
Number of pages: 13
Pages: 96-108
Publication date: 1 Dec 2017
Peer-reviewed: Yes

Publication information

Journal: Signal Processing
Volume: 141
ISSN (Print): 0165-1684
Ratings: 
  • Scopus rating (2017): CiteScore 7.1 SJR 0.94 SNIP 1.974
Original language: English
ASJC Scopus subject areas: Control and Systems Engineering, Software, Signal Processing, Computer Vision and Pattern Recognition, Electrical and Electronic Engineering
Keywords: Block matching, Complex domain, Denoising, Elsevier article, Phase imaging, Sample document, Sparsity
Source: Scopus
Source ID: 85020311730

Research output: Contribution to journalArticleScientificpeer-review

Multilinear class-specific discriminant analysis

There has been a great effort to transfer linear discriminant techniques that operate on vector data to high-order data, generally referred to as Multilinear Discriminant Analysis (MDA) techniques. Many existing works focus on maximizing the inter-class variances to intra-class variances defined on tensor data representations. However, there has not been any attempt to employ class-specific discrimination criteria for the tensor data. In this paper, we propose a multilinear subspace learning technique suitable for applications requiring class-specific tensor models. The method maximizes the discrimination of each individual class in the feature space while retains the spatial structure of the input. We evaluate the efficiency of the proposed method on two problems, i.e. facial image analysis and stock price prediction based on limit order book data.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Signal Processing, Aarhus Universitet, Laboratory of Signal Processing
Contributors: Thanh Tran, D., Gabbouj, M., Iosifidis, A.
Number of pages: 6
Pages: 131-136
Publication date: 1 Dec 2017
Peer-reviewed: Yes

Publication information

Journal: Pattern Recognition Letters
Volume: 100
ISSN (Print): 0167-8655
Ratings: 
  • Scopus rating (2017): CiteScore 5.5 SJR 0.662 SNIP 1.605
Original language: English
ASJC Scopus subject areas: Software, Signal Processing, Computer Vision and Pattern Recognition, Artificial Intelligence
Keywords: Class-specific discriminant learning, Face verification, Multilinear discriminant analysis, Stock price prediction

Bibliographical note

INT=sgn,"Thanh Tran, Dat"

Source: Scopus
Source ID: 85032300703

Research output: Contribution to journalArticleScientificpeer-review

Big Media Data Analysis

In this editorial a short introduction to the special issue on Big Media Data Analysis is given. The scope of this Editorial is to briefly present methodologies, tasks and applications of big media data analysis and to introduce the papers of the special issue. The special issue includes six papers that span various media analysis application areas like generic image description, medical image and video analysis, distance calculation acceleration and data collection.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Signal Processing, Research group: Multimedia Research Group - MRG, Aarhus Universitet, University of Milan Bicocca, Department of Informatics, Aristotle University of Thessaloniki
Contributors: Iosifidis, A., Tefas, A., Pitas, I., Gabbouj, M.
Number of pages: 4
Pages: 105-108
Publication date: 1 Nov 2017
Peer-reviewed: Yes

Publication information

Journal: Signal Processing: Image Communication
Volume: 59
ISSN (Print): 0923-5965
Ratings: 
  • Scopus rating (2017): CiteScore 4.6 SJR 0.551 SNIP 1.512
Original language: English
ASJC Scopus subject areas: Software, Signal Processing, Computer Vision and Pattern Recognition, Electrical and Electronic Engineering
Keywords: Big Media Data, Data analytics, Deep learning, Machine learning, Statistical learning

Bibliographical note

EXT="Tefas, Anastasios"

Source: Scopus
Source ID: 85033445526

Research output: Contribution to journalEditorialScientificpeer-review

Sparse Overcomplete Denoising: Aggregation Versus Global Optimization

Denoising is often addressed via sparse coding with respect to an overcomplete dictionary. There are two main approaches when the dictionary is composed of translates of an orthonormal basis. The first, traditionally employed by techniques such as wavelet cycle spinning, separately seeks sparsity w.r.t. each translate of the orthonormal basis, solving multiple partial optimizations and obtaining a collection of sparse approximations of the noise-free image, which are aggregated together to obtain a final estimate. The second approach, recently employed by convolutional sparse representations, instead seeks sparsity over the entire dictionary via a global optimization. It is tempting to view the former approach as providing a suboptimal solution of the latter. In this letter, we analyze whether global sparsity is a desirable property, and under what conditions the global optimization provides a better solution to the denoising problem. In particular, our experimental analysis shows that the two approaches attain comparable performance in case of natural images and global optimization outperforms the simpler aggregation of partial estimates only when the image admits an extremely sparse representation. We explain this phenomenon by separately studying the bias and variance of these solutions, and by noting that the variance of the global solution increases very rapidly as the original signal becomes less and less sparse.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Signal Processing, Politecnico di Milano, Los Alamos National Laboratory
Contributors: Carrera, D., Boracchi, G., Foi, A., Wohlberg, B.
Number of pages: 5
Pages: 1468-1472
Publication date: 1 Oct 2017
Peer-reviewed: Yes

Publication information

Journal: IEEE Signal Processing Letters
Volume: 24
Issue number: 10
ISSN (Print): 1070-9908
Ratings: 
  • Scopus rating (2017): CiteScore 6 SJR 0.732 SNIP 1.798
Original language: English
ASJC Scopus subject areas: Signal Processing, Applied Mathematics, Electrical and Electronic Engineering
Keywords: Convolutional sparse coding, denoising, overcomplete representations, sparse representations

Bibliographical note

EXT="Carrera, Diego"
EXT="Boracchi, Giacomo"

Source: Scopus
Source ID: 85029186566

Research output: Contribution to journalArticleScientificpeer-review

Binary Non-Negative Matrix Deconvolution for Audio Dictionary Learning

In this study, we propose an unsupervised method for dictionary learning in audio signals. The new method, called binary nonnegative matrix deconvolution (BNMD), is developed and used to discover patterns from magnitude-scale spectrograms. The BNMD models an audio spectrogram as a sum of delayed patterns having binary gains (activations). Only small subsets of patterns can be active for a given spectrogram excerpt. The proposed method was applied to speaker identification and separation tasks. The experimental results show that dictionaries obtained by the BNMD bring much higher speaker identification accuracies averaged over a range of SNRs from -6 dB to 9 dB (91.3%) than the NMD-based dictionaries (37.8-75.4%). The BNMD also gives a benefit over dictionaries obtained using vector quantization (87.8%). For bigger dictionaries the difference between the BNMD and the vector quantization (VQ) is getting smaller. For the speech separation task the BNMD dictionary gave a slight improvement over the VQ.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Signal Processing, Research group: Audio research group - ARG, Poznan University of Technology, University of Oldenburg, Yousician Ltd.
Contributors: Drgas, S., Virtanen, T., Lücke, J., Hurmalainen, A.
Number of pages: 13
Pages: 1644-1656
Publication date: 1 Aug 2017
Peer-reviewed: Yes

Publication information

Journal: IEEE/ACM Transactions on Audio Speech and Language Processing
Volume: 25
Issue number: 8
ISSN (Print): 2329-9290
Ratings: 
  • Scopus rating (2017): CiteScore 4.9 SJR 0.841 SNIP 2.152
Original language: English
ASJC Scopus subject areas: Signal Processing, Media Technology, Instrumentation, Acoustics and Ultrasonics, Linguistics and Language, Speech and Hearing, Electrical and Electronic Engineering
Keywords: Sparse coding, speaker recognition, speech separation
Electronic versions: 

Bibliographical note

EXT="Hurmalainen, Antti"

Source: Scopus
Source ID: 85028409183

Research output: Contribution to journalArticleScientificpeer-review

Power Mitigation by Performance Equalization in a Heterogeneous Reconfigurable Multicore Architecture

This paper presents an integrated self-aware computing model mitigating the power dissipation of a heterogeneous reconfigurable multicore architecture by dynamically scaling the operating frequency of each core. The power mitigation is achieved by equalizing the performance of all the cores for an uninterrupted exchange of data. The multicore platform consists of heterogeneous Coarse-Grained Reconfigurable Arrays (CGRAs) of application-specific sizes and a Reduced Instruction-Set Computing (RISC) core. The CGRAs and the RISC core are integrated with each other over a Network-on-Chip (NoC) of six nodes arranged in a topology of two rows and three columns. The RISC core constantly monitors and controls the performance of each CGRA accelerator by adjusting the operating frequencies unless the performance of all the CGRAs is optimally balanced over the platform. The CGRA cores on the platform are processing some of the most computationally-intensive signal processing algorithms while the RISC core establishes packet based synchronization between the cores for computation and communication. All the cores can access each other’s computational and memory resources while processing the kernels simultaneously and independently of each other. Besides general-purpose processing and overall platform supervision, the RISC processor manages performance equalization among all the cores which mitigates the overall dynamic power dissipation by 20.7 % for a proof-of-concept test.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Electronics and Communications Engineering, Research group: System-on-Chip for GNSS, Wireless Communications and Cyber-Physical Embedded Computing
Contributors: Hussain, W., Hoffmann, H., Ahonen, T., Nurmi, J.
Number of pages: 11
Pages: 287–297
Publication date: Jun 2017
Peer-reviewed: Yes
Early online date: 5 May 2016

Publication information

Journal: Journal of Signal Processing Systems
Volume: 87
Issue number: 3
ISSN (Print): 1939-8018
Ratings: 
  • Scopus rating (2017): CiteScore 1.7 SJR 0.216 SNIP 0.632
Original language: English
ASJC Scopus subject areas: Control and Systems Engineering, Modelling and Simulation, Hardware and Architecture, Information Systems, Signal Processing, Theoretical Computer Science
Keywords: CGRA, Dark silicon, Heterogeneous, Multicore, Power dissipation, Reconfigurable
Source: Scopus
Source ID: 84965022070

Research output: Contribution to journalArticleScientificpeer-review

Sparse phase imaging based on complex domain nonlocal BM3D techniques

The paper is addressed to 2D phase and amplitude estimation of complex-valued signals – that is, in particular, to estimation of modulo-2π interferometric phase images from periodic and noisy observations. These degradation mechanisms make phase image estimation a challenging problem. A sparse nonlocal data-adaptive imaging formalized in complex domain is used for phase and amplitude image reconstruction. Following the procedure of patch-based technique, the image is partitioned into small overlapping square patches. Block Matching Three Dimensional (BM3D) technique is developed for forming complex domain sparse spectral representations of complex-valued data. High Order Singular Value Decomposition (HOSVD) applied to BM3D groups enables the design of the orthonormal complex domain 3D transforms which are data adaptive and different for each BM3Ds group. An iterative version of the complex domain BM3D is designed from variational formulation of the problem. The convergence of this algorithm is shown. The effectiveness of the new sparse coding based algorithms is illustrated in simulation experiments where they demonstrate the state-of-the-art performance.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Signal Processing, Research group: Computational Imaging-CI
Contributors: Katkovnik, V., Egiazarian, K.
Number of pages: 14
Pages: 72-85
Publication date: 1 Apr 2017
Peer-reviewed: Yes

Publication information

Journal: Digital Signal Processing
Volume: 63
ISSN (Print): 1051-2004
Ratings: 
  • Scopus rating (2017): CiteScore 4.5 SJR 0.55 SNIP 1.397
Original language: English
ASJC Scopus subject areas: Signal Processing, Electrical and Electronic Engineering
Keywords: Complex domain image denoising, Complex domain sparsity, HOSVD, Non-local block matching, Phase imaging
Source: Scopus
Source ID: 85009165629

Research output: Contribution to journalArticleScientificpeer-review

Neighborhood Matching for Image Retrieval

In the last few years, large-scale image retrieval has attracted a lot of attention from the multimedia community. Usual approaches addressing this task first generate an initial ranking of the reference images using fast approximations that do not take into consideration the spatial arrangement of local features in the image (e.g., the bag-of-words paradigm). The top positions of the rankings are then re-estimated with verification methods that deal with more complex information, such as the geometric layout of the image. This verification step allows pruning of many false positives at the expense of an increase in the computational complexity, which may prevent its application to large-scale retrieval problems. This paper describes a geometric method known as neighborhood matching (NM), which revisits the keypoint matching process by considering a neighborhood around each keypoint and improves the efficiency of a geometric verification step in the image search system. Multiple strategies are proposed and compared to incorporate NM into a large-scale image retrieval framework. A detailed analysis and comparison of these strategies and baseline methods have been investigated. The experiments show that the proposed method not only improves the computational efficiency, but also increases the retrieval performance and outperforms state-of-the-art methods in standard datasets, such as the Oxford 5 k and 105 k datasets, for which the spatial verification step has a significant impact on the system performance.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Signal Processing, Universidad Carlos III de Madrid, Purdue University
Contributors: González-Díaz, I., Birinci, M., Díaz-De-María, F., Delp, E. J.
Number of pages: 15
Pages: 544-558
Publication date: 1 Mar 2017
Peer-reviewed: Yes

Publication information

Journal: IEEE Transactions on Multimedia
Volume: 19
Issue number: 3
ISSN (Print): 1520-9210
Ratings: 
  • Scopus rating (2017): CiteScore 7.8 SJR 0.954 SNIP 2.302
Original language: English
ASJC Scopus subject areas: Signal Processing, Media Technology, Computer Science Applications, Electrical and Electronic Engineering
Keywords: Geometric verification, image retrieval, neighborhood matching (NM), robust estimation
Source: Scopus
Source ID: 85013466531

Research output: Contribution to journalArticleScientificpeer-review

State Estimation for a Class of Piecewise Affine State-Space Models

We propose a filter for piecewise affine state-space models. In each filtering recursion, the true filtering posterior distribution is a mixture of truncated normal distributions. The proposed filter approximates the mixture with a single normal distribution via moment matching. The proposed algorithm is compared with the extended Kalman filter (EKF) in a numerical simulation, where the proposed method obtains, on average, better root mean square error than the EKF.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Automation Science and Engineering, Research area: Dynamic Systems, Research group: Positioning, Universidade Federal do Rio Grande do Sul, Porto Alegre, Linköping University
Contributors: Rui, R., Ardeshiri, T., Nurminen, H., Bazanella, A., Gustafsson, F.
Number of pages: 5
Pages: 61-65
Publication date: Jan 2017
Peer-reviewed: Yes
Early online date: 1 Dec 2016

Publication information

Journal: IEEE Signal Processing Letters
Volume: 24
Issue number: 1
ISSN (Print): 1070-9908
Ratings: 
  • Scopus rating (2017): CiteScore 6 SJR 0.732 SNIP 1.798
Original language: English
ASJC Scopus subject areas: Electrical and Electronic Engineering, Signal Processing, Applied Mathematics
Keywords: piecewise affine, state-space models, nonlinear filtering, Kalman filtering

Research output: Contribution to journalArticleScientificpeer-review

Data Flow Algorithms for Processors with Vector Extensions: Handling Actors With Internal State

Full use of the parallel computation capabilities of present and expected CPUs and GPUs requires use of vector extensions. Yet many actors in data flow systems for digital signal processing have internal state (or, equivalently, an edge that loops from the actor back to itself) that impose serial dependencies between actor invocations that make vectorizing across actor invocations impossible. Ideally, issues of inter-thread coordination required by serial data dependencies should be handled by code written by parallel programming experts that is separate from code specifying signal processing operations. The purpose of this paper is to present one approach for so doing in the case of actors that maintain state. We propose a methodology for using the parallel scan (also known as prefix sum) pattern to create algorithms for multiple simultaneous invocations of such an actor that results in vectorizable code. Two examples of applying this methodology are given: (1) infinite impulse response filters and (2) finite state machines. The correctness and performance of the resulting IIR filters and one class of FSMs are studied.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Pervasive Computing, Research area: Computer engineering, Signal Processing Research Community (SPRC), Keysight Technologies, University of Maryland
Contributors: Barford, L., Bhattacharyya, S. S., Liu, Y.
Pages: 21-31
Publication date: 2017
Peer-reviewed: Yes

Publication information

Journal: Journal of Signal Processing Systems
Volume: 87
Issue number: 1
ISSN (Print): 1939-8018
Ratings: 
  • Scopus rating (2017): CiteScore 1.7 SJR 0.216 SNIP 0.632
Original language: English
ASJC Scopus subject areas: Control and Systems Engineering, Modelling and Simulation, Hardware and Architecture, Information Systems, Signal Processing, Theoretical Computer Science
Keywords: Data flow computing, Digital signal processing, Graphics processing units, Parallel algorithms, Vector processors
Source: Scopus
Source ID: 84946115179

Research output: Contribution to journalArticleScientificpeer-review

On the existence of the solution for one-dimensional discrete phase retrieval problem

We consider the discrete form of the one-dimensional phase retrieval (1-D DPhR) problem from the point of view of input magnitude data. The direct method can provide a solution to the 1-D DPhR problem if certain conditions are satisfied by the input magnitude data, namely the corresponding trigonometric polynomial must be nonnegative. To test positivity of a trigonometric polynomial a novel DFT-based criterion is proposed. We use this DFT criterion for different sets of input magnitude data to evaluate whether the direct method applied to the 1-D DPhR problem leads to a solution in all explored cases.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Signal Processing, Technical University of Cluj-NapocaUniversitatea Tehnica din Cluj-Napoca, Tampere International Center for Signal Processing
Contributors: Rusu, C., Astola, J.
Number of pages: 8
Pages: 195–202
Publication date: 2017
Peer-reviewed: Yes

Publication information

Journal: Signal, Image and Video Processing
Volume: 11
Issue number: 2
ISSN (Print): 1863-1703
Ratings: 
  • Scopus rating (2017): CiteScore 3 SJR 0.485 SNIP 1.228
Original language: English
ASJC Scopus subject areas: Electrical and Electronic Engineering, Signal Processing
Keywords: Discrete Fourier transform, Phase retrieval, Positive trigonometric polynomials, Signal reconstruction

Bibliographical note

EXT="Rusu, Corneliu"

Source: Scopus
Source ID: 84976319640

Research output: Contribution to journalArticleScientificpeer-review

Parallel Digital Predistortion Design on Mobile GPU and Embedded Multicore CPU for Mobile Transmitters

Digital predistortion (DPD) is a widely adopted baseband processing technique in current radio transmitters. While DPD can effectively suppress unwanted spurious spectrum emissions stemming from imperfections of analog RF and baseband electronics, it also introduces extra processing complexity and poses challenges on efficient and flexible implementations, especially for mobile cellular transmitters, considering their limited computing power compared to basestations. In this paper, we present high data rate implementations of broadband DPD on modern embedded processors, such as mobile GPU and multicore CPU, by taking advantage of emerging parallel computing techniques for exploiting their computing resources. We further verify the suppression effect of DPD experimentally on real radio hardware platforms. Performance evaluation results of our DPD design demonstrate the high efficacy of modern general purpose mobile processors on accelerating DPD processing for a mobile transmitter.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Electronics and Communications Engineering, Research group: Wireless Communications and Positioning, Rice University, Univ of Oulu
Contributors: Li, K., Ghazi, A., Tarver, C., Boutellier, J., Abdelaziz, M., Anttila, L., Juntti, M., Valkama, M., Cavallaro, J. R.
Number of pages: 14
Pages: 417–430
Publication date: 2017
Peer-reviewed: Yes

Publication information

Journal: Journal of Signal Processing Systems
Volume: 89
Issue number: 3
ISSN (Print): 1939-8018
Ratings: 
  • Scopus rating (2017): CiteScore 1.7 SJR 0.216 SNIP 0.632
Original language: English
ASJC Scopus subject areas: Control and Systems Engineering, Theoretical Computer Science, Signal Processing, Information Systems, Modelling and Simulation, Hardware and Architecture
Keywords: CUDA, Digital predistortion, Mobile SoC, NEON SIMD, Software-defined radio
Source: Scopus
Source ID: 85013872658

Research output: Contribution to journalArticleScientificpeer-review

Implementation of a Multirate Resampler for Multi-carrier Systems on GPUs

Efficient sample rate conversion is of widespread importance in modern communication and signal processing systems. Although many efficient kinds of polyphase filterbank structures exist for this purpose, they are mainly geared toward serial, custom, dedicated hardware implementation for a single task. There is, therefore, a need for more flexible sample rate conversion systems that are resource-efficient, and provide high performance. To address these challenges, we present in this paper an all-software-based, fully parallel, multirate resampling method based on graphics processing units (GPUs). The proposed approach is well-suited for wireless communication systems that have simultaneous requirements on high throughput and low latency. Utilizing the multidimensional architecture of GPUs, our design allows efficient parallel processing across multiple channels and frequency bands at baseband. The resulting architecture provides flexible sample rate conversion that is designed to address modern communication requirements, including real-time processing of multiple carriers simultaneously.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Pervasive Computing, University of Maryland
Contributors: Kim, S. C., Bhattacharyya, S. S.
Number of pages: 11
Pages: 445–455
Publication date: 2017
Peer-reviewed: Yes
Early online date: 30 Mar 2017

Publication information

Journal: Journal of Signal Processing Systems
Volume: 89
Issue number: 3
ISSN (Print): 1939-8018
Ratings: 
  • Scopus rating (2017): CiteScore 1.7 SJR 0.216 SNIP 0.632
Original language: English
ASJC Scopus subject areas: Control and Systems Engineering, Theoretical Computer Science, Signal Processing, Information Systems, Modelling and Simulation, Hardware and Architecture
Keywords: Carrier aggregation, GPU-based radio, Multirate signal processing, Polyphase decimator, Polyphase interpolator, Polyphase resampler
Source: Scopus
Source ID: 85016560476

Research output: Contribution to journalArticleScientificpeer-review

Design Flow for GPU and Multicore Execution of Dynamic Dataflow Programs

Dataflow programming has received increasing attention in the age of multicore and heterogeneous computing. Modular and concurrent dataflow program descriptions enable highly automated approaches for design space exploration, optimization and deployment of applications. A great advance in dataflow programming has been the recent introduction of the RVC-CAL language. Having been standardized by the ISO, the RVC-CAL dataflow language provides a solid basis for the development of tools, design methodologies and design flows. This paper proposes a novel design flow for mapping RVC-CAL dataflow programs to parallel and heterogeneous execution platforms. Through the proposed design flow the programmer can describe an application in the RVC-CAL language and map it to multi- and many-core platforms, as well as GPUs, for efficient execution. The functionality and efficiency of the proposed approach is demonstrated by a parallel implementation of a video processing application and a run-time reconfigurable filter for telecommunications. Experiments are performed on GPU and multicore platforms with up to 16 cores, and the results show that for high-performance applications the proposed design flow provides up to 4 × higher throughput than the state-of-the-art approach in multicore execution of RVC-CAL programs.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Pervasive Computing, Research area: Computer engineering, Center for Machine Vision and Signal Analysis, Univ of Oulu
Contributors: Boutellier, J., Nyländen, T.
Number of pages: 10
Pages: 469–478
Publication date: 2017
Peer-reviewed: Yes

Publication information

Journal: Journal of Signal Processing Systems
Volume: 89
Issue number: 3
ISSN (Print): 1939-8018
Ratings: 
  • Scopus rating (2017): CiteScore 1.7 SJR 0.216 SNIP 0.632
Original language: English
ASJC Scopus subject areas: Control and Systems Engineering, Theoretical Computer Science, Signal Processing, Information Systems, Modelling and Simulation, Hardware and Architecture
Keywords: Dataflow computing, Design automation, Parallel processing, Signal processing
Source: Scopus
Source ID: 85021239311

Research output: Contribution to journalArticleScientificpeer-review

A Hybrid Task Graph Scheduler for High Performance Image Processing Workflows

Designing applications for scalability is key to improving their performance in hybrid and cluster computing. Scheduling code to utilize parallelism is difficult, particularly when dealing with data dependencies, memory management, data motion, and processor occupancy. The Hybrid Task Graph Scheduler (HTGS) improves programmer productivity when implementing hybrid workflows for multi-core and multi-GPU systems. The Hybrid Task Graph Scheduler (HTGS) is an abstract execution model, framework, and API that increases programmer productivity when implementing hybrid workflows for such systems. HTGS manages dependencies between tasks, represents CPU and GPU memories independently, overlaps computations with disk I/O and memory transfers, keeps multiple GPUs occupied, and uses all available compute resources. Through these abstractions, data motion and memory are explicit; this makes data locality decisions more accessible. To demonstrate the HTGS application program interface (API), we present implementations of two example algorithms: (1) a matrix multiplication that shows how easily task graphs can be used; and (2) a hybrid implementation of microscopy image stitching that reduces code size by ≈ 43% compared to a manually coded hybrid workflow implementation and showcases the minimal overhead of task graphs in HTGS. Both of the HTGS-based implementations show good performance. In image stitching the HTGS implementation achieves similar performance to the hybrid workflow implementation. Matrix multiplication with HTGS achieves 1.3x and 1.8x speedup over the multi-threaded OpenBLAS library for 16k × 16k and 32k × 32k size matrices, respectively.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Pervasive Computing, Research area: Computer engineering, University of Maryland Baltimore County, National Institute of Standards and Technology, Department of Electrical and Computer Engineering, University of Maryland
Contributors: Blattner, T., Keyrouz, W., Bhattacharyya, S. S., Halem, M., Brady, M.
Number of pages: 11
Pages: 457–467
Publication date: 2017
Peer-reviewed: Yes

Publication information

Journal: Journal of Signal Processing Systems
Volume: 89
Issue number: 3
ISSN (Print): 1939-8018
Ratings: 
  • Scopus rating (2017): CiteScore 1.7 SJR 0.216 SNIP 0.632
Original language: English
ASJC Scopus subject areas: Control and Systems Engineering, Theoretical Computer Science, Signal Processing, Information Systems, Modelling and Simulation, Hardware and Architecture
Keywords: Dataflow, Heterogeneous architectures, Hybrid workflows, Image processing, Matrix multiplication, Task graph
Source: Scopus
Source ID: 85025108758

Research output: Contribution to journalArticleScientificpeer-review

Minimum description length sparse modeling and region merging for lossless plenoptic image compression

This paper proposes a complete lossless compression method for exploiting the redundancy of rectified light-field data. The light-field data consists of an array of rectified subaperture images, called for short views, which are segmented into regions according to an optimized partition of the central view. Each region of a view is predictively encoded using a specifically designed sparse predictor, exploiting the smoothness of each color component in the current view, and the cross-similarities with the other color components and already encoded neighbor views. The views are encoded sequentially, using a spiral scanning order, each view being predicted based on several similar neighbor views. The essential challenge for each predictor becomes choosing the most relevant regressors, from a large number of possible regressors belonging to the neighbor views. The proposed solution here is to couple sparse predictor design and minimum description length (MDL) principle, where the data description length is measured by an implementable code length, optimized for a class of probability models. The paper introduces a region merging segmentation under MDL criterion for partitioning the views into regions having their own specific sparse predictors. In experiments, several fast sparse design methods are considered. The proposed scheme is evaluated over a database of plenoptic images, achieving better lossless compression ratios than straightforward usage of standard image and video compression methods for the spiral sequence of views.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Signal Processing, University of California San Diego
Contributors: Helin, P., Astola, P., Rao, B., Tabus, I.
Publication date: 2017
Peer-reviewed: Yes

Publication information

Journal: IEEE Journal on Selected Topics in Signal Processing
Volume: 11
Issue number: 7
ISSN (Print): 1932-4553
Ratings: 
  • Scopus rating (2017): CiteScore 11.9 SJR 1.331 SNIP 3.054
Original language: English
ASJC Scopus subject areas: Signal Processing, Electrical and Electronic Engineering
Keywords: Cameras, Data structures, Encoding, Image coding, Image color analysis, Image segmentation, light-field coding, lossless compression, minimum description length segmentation, plenoptics, sparse prediction, Spirals
Source: Scopus
Source ID: 85028989947

Research output: Contribution to journalArticleScientificpeer-review

Data Rate Assessment on L2–L3 CPU Bus and Bus between CPU and RAM in Modern CPUs

In this paper, modern CPU architecture with several different cache levels is described and current CPU performance limitations such as frequency increase bounds are discussed. As changes to the currently existing architecture are usually proposed as a way of increasing CPU performance, data rates of the internal and external CPU interfaces must be known. This information would help to assess the applicability of proposed solutions and to optimize them. This paper is aimed at obtaining real values of traffic on an L2–L3 cache interface inside a CPU and a CPU–RAM bus load, as well as showing the dependences of the total traffic on the studied interfaces on the number of active cores, CPU frequency, and test type. A measurement methodology using an Intel Performance Counter Monitor is provided and the equations used to obtain data rates from the internal CPU counters are explained. Both real-life and synthetic tests are described. The dependence of total traffic on the number of active cores and the dependence of total traffic on CPU frequency are provided as plots. The dependence of total traffic on test type is provided as a bar plot for multiple CPU frequencies.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Electronics and Communications Engineering, Yaroslavl State University
Contributors: Komar, M. S.
Number of pages: 8
Pages: 701-708
Publication date: 2017
Peer-reviewed: Yes

Publication information

Journal: Automatic Control and Computer Sciences
Volume: 51
Issue number: 7
ISSN (Print): 0146-4116
Ratings: 
  • Scopus rating (2017): CiteScore 0.6 SJR 0.218 SNIP 0.613
Original language: English
ASJC Scopus subject areas: Software, Control and Systems Engineering, Signal Processing
Keywords: data rate assessment, multicore CPUs, Network-on-Chip, NoC, System-on-Chip, Wireless Network- on-Chip, WNoC

Bibliographical note

INT=elt,"Komar, M. S."

Source: Scopus
Source ID: 85042229432

Research output: Contribution to journalArticleScientificpeer-review

Adaptive tracking of people and vehicles using mobile platforms

Tracking algorithms have important applications in detection of humans and vehicles for border security and other areas. For large-scale deployment of such algorithms, it is critical to provide methods for their cost- and energy-efficient realization. To this end, commodity mobile devices have significant potential for use as prototyping and testing platforms due to their low cost, widespread availability, and integration of advanced communications, sensing, and processing features. Prototypes developed on mobile platforms can be tested, fine-tuned, and demonstrated in the field and then provide reference implementations for application-specific disposable sensor node implementations that are targeted for deployment. In this paper, we develop a novel, adaptive tracking system that is optimized for energy-efficient, real-time operation on off-the-shelf mobile platforms. Our tracking system applies principles of dynamic data-driven application systems (DDDAS) to periodically monitor system operating characteristics and apply these measurements to dynamically adapt the specific classifier configurations that the system employs. Our resulting adaptive approach enables powerful optimization of trade-offs among energy consumption, real-time performance, and tracking accuracy based on time-varying changes in operational characteristics. Through experiments employing an Android-based tablet platform, we demonstrate the efficiency of our proposed tracking system design for multimode detection of human and vehicle targets.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Pervasive Computing, Research area: Computer engineering, University of Maryland, U.S. Army Research Laboratory, Technische Universitat Munchen
Contributors: Ben Salem, H., Damarla, T., Sudusinghe, K., Stechele, W., Bhattacharyya, S. S.
Publication date: 1 Dec 2016
Peer-reviewed: Yes

Publication information

Journal: Eurasip Journal on Advances in Signal Processing
Volume: 2016
Issue number: 1
Article number: 65
ISSN (Print): 1687-6172
Ratings: 
  • Scopus rating (2016): CiteScore 2.5 SJR 0.345 SNIP 1.088
Original language: English
ASJC Scopus subject areas: Hardware and Architecture, Signal Processing, Electrical and Electronic Engineering
Keywords: Acoustic sensors, Dataflow graphs, DDDAS, Mobile platforms, Signal processing systems, Target tracking
Source: Scopus
Source ID: 84971500315

Research output: Contribution to journalArticleScientificpeer-review

Generalized Hampel Filters

The standard median filter based on a symmetric moving window has only one tuning parameter: the window width. Despite this limitation, this filter has proven extremely useful and has motivated a number of extensions: weighted median filters, recursive median filters, and various cascade structures. The Hampel filter is a member of the class of decsion filters that replaces the central value in the data window with the median if it lies far enough from the median to be deemed an outlier. This filter depends on both the window width and an additional tuning parameter t, reducing to the median filter when t=0, so it may be regarded as another median filter extension. This paper adopts this view, defining and exploring the class of generalized Hampel filters obtained by applying the median filter extensions listed above: weighted Hampel filters, recursive Hampel filters, and their cascades. An important concept introduced here is that of an implosion sequence, a signal for which generalized Hampel filter performance is independent of the threshold parameter t. These sequences are important because the added flexibility of the generalized Hampel filters offers no practical advantage for implosion sequences. Partial characterization results are presented for these sequences, as are useful relationships between root sequences for generalized Hampel filters and their median-based counterparts. To illustrate the performance of this filter class, two examples are considered: one is simulation-based, providing a basis for quantitative evaluation of signal recovery performance as a function of t, while the other is a sequence of monthly Italian industrial production index values that exhibits glaring outliers.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Signal Processing, Research group: Video, DataRobot, Aalto University
Contributors: Pearson, R. K., Neuvo, Y., Astola, J., Gabbouj, M.
Publication date: 1 Dec 2016
Peer-reviewed: Yes

Publication information

Journal: Eurasip Journal on Advances in Signal Processing
Volume: 2016
Issue number: 1
Article number: 87
ISSN (Print): 1687-6172
Ratings: 
  • Scopus rating (2016): CiteScore 2.5 SJR 0.345 SNIP 1.088
Original language: English
ASJC Scopus subject areas: Hardware and Architecture, Signal Processing, Electrical and Electronic Engineering
Electronic versions: 
Source: Scopus
Source ID: 84981165367

Research output: Contribution to journalArticleScientificpeer-review

Blind Separation of Audio Mixtures Through Nonnegative Tensor Factorization of Modulation Spectrograms

This paper presents an algorithm for unsupervised single-channel source separation of audio mixtures. The approach specifically addresses the challenging case of separation where no training data are available. By representing mixtures in the modulation spectrogram (MS) domain, we exploit underlying similarities in patterns present across frequency. A three-dimensional tensor factorization is able to take advantage of these redundant patterns, and is used to separate a mixture into an approximated sum of components by minimizing a divergence cost. Furthermore, we show that the basic tensor factorization can be extended with convolution in time being used to improve separation results and provide update rules to learn components in such a manner. Following factorization, sources are reconstructed in the audio domain from estimated components using a novel approach based on reconstruction masks that are learned using MS activations, and then applied to a mixture spectrogram. We demonstrate that the proposed method produces superior separation performance to a spectrally based nonnegative matrix factorization approach, in terms of source-to-distortion ratio. We also compare separation with the perceptually motivated interference-related perceptual score metric and identify cases with higher performance.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Signal Processing, Research group: Audio research group
Contributors: Barker, T., Virtanen, T.
Number of pages: 13
Pages: 2377-2389
Publication date: 1 Dec 2016
Peer-reviewed: Yes

Publication information

Journal: Ieee-Acm transactions on audio speech and language processing
Volume: 24
Issue number: 12
ISSN (Print): 2329-9290
Ratings: 
  • Scopus rating (2016): CiteScore 2.7 SJR 0.711 SNIP 3.007
Original language: English
ASJC Scopus subject areas: Signal Processing, Media Technology, Instrumentation, Acoustics and Ultrasonics, Linguistics and Language, Speech and Hearing, Electrical and Electronic Engineering
Keywords: Factorization, nonnegative matrix factorization (NMF), source separation, speech enhancement
Source: Scopus
Source ID: 84991442139

Research output: Contribution to journalArticleScientificpeer-review

Ensembles of dense and dense sampling descriptors for the HEp-2 cells classification problem

The classification of Human Epithelial (HEp-2) cells images, acquired through Indirect Immunofluorescence (IIF) microscopy, is an effective method to identify staining patterns in patient sera. Indeed it can be used for diagnostic purposes, in order to reveal autoimmune diseases. However, the automated classification of IIF HEp-2 cell patterns represents a challenging task, due to the large intra-class and the small inter-class variability. Consequently, recent HEp-2 cell classification contests have greatly spurred the development of new IIF image classification systems.Here we propose an approach for the automatic classification of IIF HEp-2 cell images by fusion of several texture descriptors by ensemble of support vector machines combined by sum rule. Its effectiveness is evaluated using the HEp-2 cells dataset used for the "Performance Evaluation of Indirect Immunofluorescence Image Analysis Systems" contest, hosted by the International Conference on Pattern Recognition in 2014: the accuracy on the testing set is 79.85%.The same dataset was used to test an ensemble of ternary-encoded local phase quantization descriptors, built by perturbation approaches: the accuracy on the training set is 84.16%. Finally, this ensemble was validated on 14 additional datasets, obtaining the best performance on 11 datasets.Our MATLAB code is available at https://www.dei.unipd.it/node/2357.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Electronics and Communications Engineering, Research group: Computational Biophysics and Imaging Group, BioMediTech, Integrated Technologies for Tissue Engineering Research (ITTE), Universita degli Studi di Padova, Italy, University of Bologna
Contributors: Nanni, L., Lumini, A., dos Santos, F. L. C., Paci, M., Hyttinen, J.
Pages: 28-35
Publication date: 15 Oct 2016
Peer-reviewed: Yes

Publication information

Journal: Pattern Recognition Letters
Volume: 82
ISSN (Print): 0167-8655
Ratings: 
  • Scopus rating (2016): CiteScore 5.2 SJR 0.729 SNIP 1.678
Original language: English
ASJC Scopus subject areas: Software, Artificial Intelligence, Computer Vision and Pattern Recognition, Signal Processing
Keywords: Bag-of-features, Ensemble, HEp-2 cell classification, Machine learning, Support vector machine, Texture descriptors
URLs: 
Source: Scopus
Source ID: 84961195136

Research output: Contribution to journalArticleScientificpeer-review

Image interpolation based on non-local geometric similarities and directional gradients

Image interpolation offers an efficient way to compose a high-resolution (HR) image from the observed low-resolution (LR) image. Advanced interpolation techniques design the interpolation weighting coefficients by solving a minimum mean-square-error (MMSE) problem in which the local geometric similarity is often considered. However, using local geometric similarities cannot usually make the MMSE-based interpolation as reliable as expected. To solve this problem, we propose a robust interpolation scheme by using the nonlocal geometric similarities to construct the HR image. In our proposed method, the MMSE-based interpolation weighting coefficients are generated by solving a regularized least squares problem that is built upon a number of dual-reference patches drawn from the given LR image and regularized by the directional gradients of these patches. Experimental results demonstrate that our proposed method offers a remarkable quality improvement as compared to some state-of-the-art methods, both objectively and subjectively.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Signal Processing, Research group: Video, University of Electronic Science and Technology of China
Contributors: Zhu, S., Zeng, B., Zeng, L., Gabbouj, M.
Number of pages: 13
Pages: 1707-1719
Publication date: 1 Sep 2016
Peer-reviewed: Yes

Publication information

Journal: IEEE Transactions on Multimedia
Volume: 18
Issue number: 9
ISSN (Print): 1520-9210
Ratings: 
  • Scopus rating (2016): CiteScore 8.1 SJR 1.298 SNIP 2.536
Original language: English
ASJC Scopus subject areas: Signal Processing, Media Technology, Computer Science Applications, Electrical and Electronic Engineering
Keywords: Directional gradient, geometric similarity, image interpolation, minimum mean square error (MMSE)
Source: Scopus
Source ID: 84983409176

Research output: Contribution to journalArticleScientificpeer-review

A software tool for studying the size and shape of human cardiomyocytes

Background and objectives Due to development of imaging systems the amount of digital images obtained in the biological field has been growing in recent years. These images contain information that is not directly measurable, e.g. the area covered by a single cell. In most of the current imaging programs the regions of interest (ROI), e.g. individual cells, need to be manually outlined. Automation of processing and analyzing the images would ease researchers’ workload and provide results that are more reliable. In this work our goal was to write software that automatically segments human cardiomyocytes from images, calculates their areas and variations in the direction of the largest and smallest spread. Results We developed software that eased the workload of biomedical laboratory personnel such that they do not have to do manual image segmentation or learn to use software that requires programming skills. The software made a correct segmentation in most of the cases and outperformed the intensity oriented baseline method written in ImageJ in 95% of comparisons. The baseline method estimated cell- and background areas by averaging dark background and bright foreground areas. Conclusions Our software can be used in the calculation of cell areas and extents in the case where immunolabeled cells are imaged with a fluorescent microscope. In the future the functionality of the program could be extended with machine learning methods that use the user actions as teaching material in the cases where automatic segmentation fails.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Tampere University Hospital, BioMediTech
Contributors: Rasku, J., Ojala, M., Pölönen, R. P., Joutsijoki, H., Gizatdinova, Y., Laurikkala, J., Kartasalo, K., Aalto-Setälä, K., Juhola, M.
Number of pages: 6
Pages: 134-139
Publication date: 1 Sep 2016
Peer-reviewed: Yes

Publication information

Journal: Biomedical Signal Processing and Control
Volume: 30
ISSN (Print): 1746-8094
Ratings: 
  • Scopus rating (2016): CiteScore 4.6 SJR 0.674 SNIP 1.725
Original language: English
ASJC Scopus subject areas: Health Informatics, Signal Processing
Keywords: Cardiomyocyte, Segmentation, Threshold
Source: Scopus
Source ID: 84978280164

Research output: Contribution to journalArticleScientificpeer-review

Nyström-based approximate kernel subspace learning

In this paper, we describe a method for the determination of a subspace of the feature space in kernel methods, which is suited to large-scale learning problems. Linear model learning in the obtained space corresponds to a nonlinear model learning process in the input space. Since the obtained feature space is determined only by exploiting properties of the training data, this approach can be used for generic nonlinear pattern recognition. That is, nonlinear data mapping can be considered to be a pre-processing step exploiting nonlinear relationships between the training data. Linear techniques can be subsequently applied in the new feature space and, thus, they can model nonlinear properties of the problem at hand. In order to appropriately address the inherent problem of kernel learning methods related to their time and memory complexities, we follow an approximate learning approach. We show that the method can lead to considerable operation speed gains and achieve very good performance. Experimental results verify our analysis.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Signal Processing, Research group: Video, Research Community on Data-to-Decision (D2D)
Contributors: Iosifidis, A., Gabbouj, M.
Number of pages: 8
Pages: 190-197
Publication date: Sep 2016
Peer-reviewed: Yes

Publication information

Journal: Pattern Recognition
ISSN (Print): 0031-3203
Ratings: 
  • Scopus rating (2016): CiteScore 9 SJR 1.501 SNIP 3.005
Original language: English
ASJC Scopus subject areas: Software, Artificial Intelligence, Computer Vision and Pattern Recognition, Signal Processing
Keywords: Kernel methods, Nonlinear pattern recognition, Nonlinear projection trick, Nyström approximation
Source: Scopus
Source ID: 85013223573

Research output: Contribution to journalArticleScientificpeer-review

Compressive Detection of Random Subspace Signals

The problem of compressive detection of random subspace signals is studied. We consider signals modeled as s = Hx where H is an N × K matrix with K ≤ N and x ~ N(0K,12IK). We say that signal s lies in or leans toward a subspace if the largest eigenvalue of HHT is strictly greater than its smallest eigenvalue. We first design a measurement matrix Φ = [ΦsT, ΦoT]T comprising of two sub-matrices Φs and Φo where Φs projects the signal to the strongest left-singular vectors, i.e., the left-singular vectors corresponding to the largest singular values, of subspace matrix H and Φo projects it to the weakest left-singular vectors. We then propose two detectors that work based on the difference in energies of the samples measured by the two sub-matrices Φs and Φo and provide theoretical proofs for their optimality. Simplified versions of the proposed detectors for the case when the variance of noise is known are also provided. Furthermore, we study the performance of the detector when measurements are imprecise and show how imprecision can be compensated by employing more measurement devices. The problem is then re-formulated for the generalized case when the signal lies in the union of a finite number of linear subspaces instead of a single linear subspace. Finally, we study the performance of the proposed methods by simulation examples.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Electronics and Communications Engineering, Research group: Wireless Communications and Positioning, Electrical Engineering Department, University of California, Los Angeles (UCLA)
Contributors: Razavi, A., Valkama, M., Cabric, D.
Number of pages: 14
Pages: 4166-4179
Publication date: 15 Aug 2016
Peer-reviewed: Yes

Publication information

Journal: IEEE Transactions on Signal Processing
Volume: 64
Issue number: 16
ISSN (Print): 1053-587X
Ratings: 
  • Scopus rating (2016): CiteScore 8.7 SJR 1.385 SNIP 2.627
Original language: English
ASJC Scopus subject areas: Electrical and Electronic Engineering, Signal Processing
Keywords: Compressive detection, F -distribution, hypothesis testing, random subspace signals, unknown noise variance
Source: Scopus
Source ID: 84980329115

Research output: Contribution to journalArticleScientificpeer-review

Variance Stabilization for Noisy+Estimate Combination in Iterative Poisson Denoising

We denoise Poisson images with an iterative algorithm that progressively improves the effectiveness of variance-stabilizing transformations (VST) for Gaussian denoising filters. At each iteration, a combination of the Poisson observations with the denoised estimate from the previous iteration is treated as scaled Poisson data and filtered through a VST scheme. Due to the slight mismatch between a true scaled Poisson distribution and this combination, a special exact unbiased inverse is designed. We present an implementation of this approach based on the BM3D Gaussian denoising filter. With a computational cost at worst twice that of the noniterative scheme, the proposed algorithm provides significantly better quality, particularly at low signal-to-noise ratio, outperforming much costlier state-of-the-art alternatives.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Signal Processing, Research group: Signal and Image Restoration-RST
Contributors: Azzari, L., Foi, A.
Number of pages: 5
Pages: 1086-1090
Publication date: 1 Aug 2016
Peer-reviewed: Yes

Publication information

Journal: IEEE Signal Processing Letters
Volume: 23
Issue number: 8
ISSN (Print): 1070-9908
Ratings: 
  • Scopus rating (2016): CiteScore 5.3 SJR 0.798 SNIP 1.806
Original language: English
ASJC Scopus subject areas: Electrical and Electronic Engineering, Signal Processing, Applied Mathematics
Keywords: Anscombe transformation, image denoising, iterative filtering, photon-limited imaging, Poisson noise
Electronic versions: 
Additional files: 
Source: Scopus
Source ID: 84979891796

Research output: Contribution to journalArticleScientificpeer-review

Optimization of Flexible Filter Banks Based on Fast Convolution

Multirate filter banks can be implemented efficiently using fast-convolution (FC) processing. The main advantage of the FC filter banks (FC-FB) compared with the conventional polyphase implementations is their increased flexibility, that is, the number of channels, their bandwidths, and the center frequencies can be independently selected. In this paper, an approach to optimize the FC-FBs is proposed. First, a subband representation of the FC-FB is derived. Then, the optimization problems are formulated with the aid of the subband model. Finally, these problems are conveniently solved with the aid of a general nonlinear optimization algorithm. Several examples are included to demonstrate the proposed overall design scheme as well as to illustrate the efficiency and the flexibility of the resulting FC-FB.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Electronics and Communications Engineering, Research group: Wireless Communications and Positioning
Contributors: Yli-Kaakinen, J., Renfors, M.
Pages: 101-111
Publication date: Aug 2016
Peer-reviewed: Yes

Publication information

Journal: Journal of Signal Processing Systems
Volume: 85
Issue number: 1
ISSN (Print): 1939-8018
Ratings: 
  • Scopus rating (2016): CiteScore 1.6 SJR 0.212 SNIP 0.677
Original language: English
ASJC Scopus subject areas: Control and Systems Engineering, Modelling and Simulation, Hardware and Architecture, Information Systems, Signal Processing, Theoretical Computer Science
Keywords: Digital filters, Filter banks, Multirate signal processing, Optimization, Sampling rate conversion
Source: Scopus
Source ID: 84929682954

Research output: Contribution to journalArticleScientificpeer-review

Visual Voice Activity Detection in the Wild

The visual voice activity detection (V-VAD) problem in unconstrained environments is investigated in this paper. A novel method for V-VAD in the wild, exploiting local shape and motion information appearing at spatiotemporal locations of interest for facial video segment description and the bag of words model for facial video segment representation, is proposed. Facial video segment classification is subsequently performed using the state-of-The-Art classification algorithms. Experimental results on one publicly available V-VAD dataset denote the effectiveness of the proposed method, since it achieves better generalization performance in unseen users, when compared to the recently proposed state-of-The-Art methods. Additional results on a new unconstrained dataset provide evidence that the proposed method can be effective even in such cases in which any other existing method fails.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Signal Processing, Aristotle University of Thessaloniki
Contributors: Patrona, F., Iosifidis, A., Tefas, A., Nikolaidis, N., Pitas, I.
Number of pages: 11
Pages: 967-977
Publication date: 1 Jun 2016
Peer-reviewed: Yes

Publication information

Journal: IEEE Transactions on Multimedia
Volume: 18
Issue number: 6
ISSN (Print): 1520-9210
Ratings: 
  • Scopus rating (2016): CiteScore 8.1 SJR 1.298 SNIP 2.536
Original language: English
ASJC Scopus subject areas: Electrical and Electronic Engineering, Signal Processing, Media Technology, Computer Science Applications
Keywords: Action Recognition, Bag of Words model, Voice Activity Detection in the wild
Source: Scopus
Source ID: 84971281783

Research output: Contribution to journalArticleScientificpeer-review

Rotation Invariant Texture Description Using Symmetric Dense Microblock Difference

This letter is devoted to the problem of rotation invariant texture classification. Novel rotation invariant feature, symmetric dense microblock difference (SDMD), is proposed which captures the information at different orientations and scales. N-fold symmetry is introduced in the feature design configuration, while retaining the random structure that provides discriminative power. The symmetry is utilized to achieve a rotation invariance. The SDMD is extracted using an image pyramid and encoded by the Fisher vector approach resulting in a descriptor which captures variations at different resolutions without increasing the dimensionality. The proposed image representation is combined with the linear SVM classifier. Extensive experiments are conducted on four texture data sets [Brodatz, UMD, UIUC, and Flickr material data set (FMD)] using standard protocols. The results demonstrate that our approach outperforms the state of the art in texture classification. The MATLAB code is made available.1 1Matlab Code: http://www.cs.tut.fi/~mehta/symdmd.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Signal Processing, Research group: Computational Imaging-CI
Contributors: Mehta, R., Egiazarian, K.
Number of pages: 5
Pages: 833-837
Publication date: 1 Jun 2016
Peer-reviewed: Yes

Publication information

Journal: IEEE Signal Processing Letters
Volume: 23
Issue number: 6
ISSN (Print): 1070-9908
Ratings: 
  • Scopus rating (2016): CiteScore 5.3 SJR 0.798 SNIP 1.806
Original language: English
ASJC Scopus subject areas: Electrical and Electronic Engineering, Signal Processing, Applied Mathematics
Keywords: image representation, local features, Rotation invariant features, texture classification
Source: Scopus
Source ID: 84970004897

Research output: Contribution to journalArticleScientificpeer-review

A Wideband Front-End Receiver Implementation on GPUs

Modern communication systems have frequency bands that are shared with multiple channels. A typical front-end transceiver is responsible for processing multiple channels simultaneously within the band. Although it is simpler to design a dedicated sub-transceiver for each channel, the overall cost of implementation is prohibitive. It is more desirable to design a single system that can process many channels at the same time. However, it is difficult to realize such a transceiver in wireless communication systems, since it needs to accommodate different standards, data rates, sampling rates, etc. In this paper, we address the challenges of flexible, cost-effective, multi-channel implementation of wideband receiver systems. In particular, we develop a novel implementation by applying graphics processing unit (GPU) technology to a wideband receiver that processes multiple channels at the same time, including channelization and arbitrary resampling. Our proposed new receiver architecture is flexible and reconfigurable via software, while providing high throughput and low latency.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Pervasive Computing, Research area: Computer engineering, University of Maryland, Department of Electrical and Computer Engineering
Contributors: Kim, S. C., Bhattacharyya, S. S.
Number of pages: 11
Pages: 2602-2612
Publication date: 15 May 2016
Peer-reviewed: Yes

Publication information

Journal: IEEE Transactions on Signal Processing
Volume: 64
Issue number: 10
ISSN (Print): 1053-587X
Ratings: 
  • Scopus rating (2016): CiteScore 8.7 SJR 1.385 SNIP 2.627
Original language: English
ASJC Scopus subject areas: Electrical and Electronic Engineering, Signal Processing
Keywords: Arbitrary resampler, carrier aggregation, GPU front-end receiver, GPU-based radio, Polyphase channelizer
Source: Scopus
Source ID: 84968750704

Research output: Contribution to journalArticleScientificpeer-review

Statistical analysis of interference for nanoscale electromechanical wireless communication at VHF-band

Nanoscale electromechanical wireless communication with on-off keying in the very high frequency (VHF) band (30-300 MHz) is studied for a receiver using a carbon nanotube (CNT). Previous studies on this topic have only considered continuous wave (CW) on-off keying which suffers from spectral widening due to sharp changes in the signal. Effects of the inter-symbol interference (ISI), the co-channel interference, and the adjacent channel interference on the received signal statistics have not been analyzed. The rise- and fall-times associated with the filtering of the incoming signal by the mechanical frequency response of the receiver's CNT have also been ignored. In this paper, Fourier-series based modeling and statistical analysis of decision variables are performed. The results and modeling in this study enable performance evaluation of CNT based receivers with an arbitrary number of interfering signals with arbitrary pulse shapes, and fully incorporates the transient signal components. Received signal statistics under interference are derived using the developed model. Numerical results are presented for Hanning pulse and trapezoidal pulse (which includes rectangular pulses corresponding to CW as a special case). The required guard intervals between pulses to mitigate ISI, required frequency separation between channels, and required spatial separation of co-channel networks (frequency reuse distance) are shown. These results show that large frequency reuse distance is required, limiting efficient spectrum utilization. However, the ISI and adjacent channel interference can be controlled more easily with a proper selection of parameters.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Electronics and Communications Engineering, Research group: Emerging Technologies for Nano-Bio-Info-Cogno, University of Oulu, Georgia Institute of Technology, School of Electrical and Computer Engineering, Nano Communication Centre, Aristotle University of Thessaloniki, School of Electrical and Computer Engineering
Contributors: Lehtomäki, J. J., Bicen, A. O., Akyildiz, I. F.
Number of pages: 11
Pages: 2040-2050
Publication date: 15 Apr 2016
Peer-reviewed: Yes

Publication information

Journal: IEEE Transactions on Signal Processing
Volume: 64
Issue number: 8
ISSN (Print): 1053-587X
Ratings: 
  • Scopus rating (2016): CiteScore 8.7 SJR 1.385 SNIP 2.627
Original language: English
ASJC Scopus subject areas: Electrical and Electronic Engineering, Signal Processing
Keywords: Carbon nanotube, frequency division multiple access, nanodevice, nanonetwork, on-off keying, VHF-band, wireless communication

Bibliographical note

INT=elt,"Bicen, A. Ozan"

Source: Scopus
Source ID: 84964402214

Research output: Contribution to journalArticleScientificpeer-review

Which wavelength is the best for arterial pulse waveform extraction using laser speckle imaging?

A multi-wavelengths analysis for pulse waveform extraction using laser speckle is conducted. The proposed system consists of three coherent light sources (532 nm, 635 nm, 850 nm). A bench-test composed of a moving skin-like phantom (silicone membrane) is used to compare the results obtained from different wavelengths. The system is able to identify a skin-like phantom vibration frequency, within physiological values, with a minimum error of 0.5 mHz for the 635 nm and 850 nm wavelengths and a minimum error of 1.3 mHz for the 532 nm light wavelength using a FFT-based algorithm. The phantom velocity profile is estimated with an error ranging from 27% to 9% using a bidimensional correlation coefficient-based algorithm. An in vivo trial is also conducted, using the 532 nm and 635 nm laser sources. The 850 nm light source has not been able to extract the pulse waveform. The heart rate is identified with a minimum error of 0.48 beats per minute for the 532 nm light source and a minimal error of 1.15 beats per minute for the 635 nm light source. Our work reveals that a laser speckle-based system with a 532 nm wavelength is able to give arterial pulse waveform with better results than those given with a 635 nm laser.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Electronics and Communications Engineering, Research group: Computational Biophysics and Imaging Group, LARIS-Laboratoire Angevin de Recherche en Ingénierie des Systèmes, Center for Mathematics Probability and Statistics
Contributors: Vaz, P., Pereira, T., Figueiras, E., Correia, C., Humeau-Heurtier, A., Cardoso, J.
Number of pages: 8
Pages: 188-195
Publication date: Mar 2016
Peer-reviewed: Yes

Publication information

Journal: Biomedical Signal Processing and Control
Volume: 25
ISSN (Print): 1746-8094
Ratings: 
  • Scopus rating (2016): CiteScore 4.6 SJR 0.674 SNIP 1.725
Original language: English
ASJC Scopus subject areas: Health Informatics, Signal Processing
Keywords: Arterial pulse waveform, Correlation, Fast Fourier transform, Laser speckle, Multi-spectral
Source: Scopus
Source ID: 84950341719

Research output: Contribution to journalArticleScientificpeer-review

Importance of maintenance data quality in extended warranty simulation

As manufacturing industries are transforming towards service orientation, predicting the costs of product-service systems is becoming essential. Simulation is one possibility for evaluating the costs and risks involved in product-service systems, such as extended warranty agreements. We conducted a case study with a globally operating manufacturer of industrial goods who also provides services for the equipment. We created equipment performance simulation (EPSi) models and a tool, EPSitor, for using the models in predicting extended warranty costs. However, reliable simulation results require good quality maintenance and operation data from existing installations. We discovered that it is difficult to collect the data needed for simulations and there were many challenges with data quality. Quality problems were mainly observed in manually collected data. Insufficient data quality leads to a wider margin of error in the simulation models, which increases business risk. Identifying these challenges is the first step in transforming the data collection routines to support equipment performance simulations. The key to long-term business benefits of simulation is to acknowledge the importance of data quality and to establish efficient data collection routines. Future research should find ways to motivate maintenance technicians to collect good quality data. This would contribute to more accurate cost analysis and thus to better profitability of extended warranty contracts.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Mechanical Engineering and Industrial Systems, Research group: Käyttövarmuuden suunnittelu ja kunnossapito, Research area: Life-cycle Management, Aalto University
Contributors: Mahlamäki, K., Niemi, A., Jokinen, J., Borgman, J.
Number of pages: 8
Pages: 3-10
Publication date: 1 Jan 2016
Peer-reviewed: Yes

Publication information

Journal: International Journal of COMADEM
Volume: 19
Issue number: 1
ISSN (Print): 1363-7681
Ratings: 
  • Scopus rating (2016): CiteScore 0.2 SJR 0.128 SNIP 0.163
Original language: English
ASJC Scopus subject areas: Electrical and Electronic Engineering, Industrial and Manufacturing Engineering, Safety, Risk, Reliability and Quality, Bioengineering, Signal Processing, Strategy and Management
Keywords: Asset management, Data quality, Hitman factors

Bibliographical note

INT=mei,”Jokinen, Juuso”

Source: Scopus
Source ID: 84960940492

Research output: Contribution to journalArticleScientificpeer-review

Online tests of Kalman filter consistency

The normalised innovation squared (NIS) test, which is used to assess whether a Kalman filter's noise assumptions are consistent with realised measurements, can be applied online with real data, and does not require future data, repeated experiments or knowledge of the true state. In this work, it is shown that the NIS test is equivalent to three other model criticism procedures, which are as follows: (i) it can be derived as a Bayesian p-test for the prior predictive distribution; (ii) as a nested-model parameter significance test; and (iii) from a recently-proposed filter residual test. A new NIS-like test corresponding to a posterior predictive Bayesian p-test is presented.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Automation Science and Engineering, Research group: Positioning
Contributors: Piché, R.
Pages: 115–124
Publication date: 2016
Peer-reviewed: Yes

Publication information

Journal: International Journal of Adaptive Control and Signal Processing
Volume: 30
Issue number: 1
ISSN (Print): 0890-6327
Ratings: 
  • Scopus rating (2016): CiteScore 3.8 SJR 0.749 SNIP 1.023
Original language: English
ASJC Scopus subject areas: Control and Systems Engineering, Electrical and Electronic Engineering, Signal Processing
Keywords: Kalman filter, Model consistency, Normalised innovations squared, Predictive distribution
Electronic versions: 
Source: Scopus
Source ID: 84954027695

Research output: Contribution to journalArticleScientificpeer-review

Still image/video frame lossy compression providing a desired visual quality

The problem of how to automatically provide a desired (required) visual quality in lossy compression of still images and video frames is considered in this paper. The quality can be measured based on different conventional and visual quality metrics. In this paper, we mainly employ human visual system (HVS) based metrics PSNR-HVS-M and MSSIM since both of them take into account several important peculiarities of HVS. To provide a desired visual quality with high accuracy, iterative image compression procedures are proposed and analyzed. An experimental study is performed for a large number of grayscale test images. We demonstrate that there exist several coders for which the number of iterations can be essentially decreased using a reasonable selection of the starting value and the variation interval for the parameter controlling compression (PCC). PCC values attained at the end of the iterative procedure may heavily depend upon the coder used and the complexity of the image. Similarly, the compression ratio also considerably depends on the above factors. We show that for some modern coders that take HVS into consideration it is possible to give practical recommendations on setting a fixed PCC to provide a desired visual quality in a non-iterative manner. The case when original images are corrupted by visible noise is also briefly studied.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Signal Processing, Research group: Computational Imaging-CI, National Aerospace University
Contributors: Zemliachenko, A., Lukin, V., Ponomarenko, N., Egiazarian, K., Astola, J.
Pages: 697-718
Publication date: 2016
Peer-reviewed: Yes

Publication information

Journal: Multidimensional Systems and Signal Processing
Volume: 27
Issue number: 3
ISSN (Print): 0923-6082
Ratings: 
  • Scopus rating (2016): CiteScore 3.4 SJR 0.424 SNIP 1.109
Original language: English
ASJC Scopus subject areas: Computer Science Applications, Information Systems, Signal Processing, Software, Artificial Intelligence, Hardware and Architecture, Applied Mathematics
Keywords: Compression ratio, Lossy compression, Required quality, Visual quality metrics
Source: Scopus
Source ID: 84930357751

Research output: Contribution to journalArticleScientificpeer-review

IEEE 802.11ac MIMO Transceiver Baseband Processing on a VLIW Processor

Wireless standards are evolving rapidly due to the exponential growth in the number of portable devices along with the applications with high data rate requirements. Adaptable software based signal processing implementations for these devices can make the deployment of the constantly evolving standards faster and less expensive. The flagship technology from the IEEE WLAN family, the IEEE 802.11ac, aims at achieving very high throughputs in local area connectivity scenarios. This article presents a software based implementation for the Multiple Input and Multiple Output (MIMO) transmitter and receiver baseband processing conforming to the IEEE 802.11ac standard which can achieve transmission bit rates beyond 1Gbps. This work focuses on the Physical layer frequency domain processing. Various configurations, including 2×2 and 4×4 MIMO are considered for the implementation. To utilize the available data and instruction level parallelism, a DSP core with vector extensions is selected as the implementation platform. Then, the feasibility of the presented software-based solution is assessed by studying the number of clock cycles and power consumption of the different scenarios implemented on this core. Such Software Defined Radio based approaches can potentially offer more flexibility, high energy efficiency, reduced design efforts and thus shorter time-to-market cycles in comparison with the conventional fixed-function hardware methods.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Electronics and Communications Engineering, Research group: Wireless Communications and Positioning, Department of Pervasive Computing, Research area: Computer engineering
Contributors: Aghababaeetafreshi, M., Lehtonen, L. K., Levanen, T., Valkama, M., Takala, J.
Publication date: 2016
Peer-reviewed: Yes

Publication information

Journal: Journal of Signal Processing Systems
ISSN (Print): 1939-8018
Ratings: 
  • Scopus rating (2016): CiteScore 1.6 SJR 0.212 SNIP 0.677
Original language: English
ASJC Scopus subject areas: Control and Systems Engineering, Modelling and Simulation, Hardware and Architecture, Information Systems, Signal Processing, Theoretical Computer Science
Keywords: MIMO, OFDM, Parallel processing, Software defined radio, VLIW, WLAN

Bibliographical note

ORG=elt,0.5
ORG=tie,0.5

Source: Scopus
Source ID: 84942023616

Research output: Contribution to journalArticleScientificpeer-review

Instrumentation-Driven Validation of Dataflow Applications

Dataflow modeling offers a myriad of tools for designing and optimizing signal processing systems. A designer is able to take advantage of dataflow properties to effectively tune the system in connection with functionality and different performance metrics. However, a disparity in the specification of dataflow properties and the final implementation can lead to incorrect behavior that is difficult to detect. This motivates the problem of ensuring consistency between dataflow properties that are declared or otherwise assumed as part of dataflow-based application models, and the dataflow behavior that is exhibited by implementations that are derived from the models. In this paper, we address this problem by introducing a novel dataflow validation framework (DVF) that is able to identify disparities between an application’s formal dataflow representation and its implementation. DVF works by instrumenting the implementation of an application and monitoring the instrumentation data as the application executes. This monitoring process is streamlined so that DVF achieves validation without major overhead. We demonstrate the utility of our DVF through design and implementation case studies involving an automatic speech recognition application, a JPEG encoder, and an acoustic tracking application.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Pervasive Computing, Research area: Computer engineering, Signal Processing Research Community (SPRC), University of Maryland, Technische Universitat Munchen, Institute for Advanced Computer Studies
Contributors: Chukhman, I., Jiao, Y., Salem, H. B., Bhattacharyya, S. S.
Pages: 383–397
Publication date: 2016
Peer-reviewed: Yes

Publication information

Journal: Journal of Signal Processing Systems
Volume: 84
Issue number: 3
ISSN (Print): 1939-8018
Ratings: 
  • Scopus rating (2016): CiteScore 1.6 SJR 0.212 SNIP 0.677
Original language: English
ASJC Scopus subject areas: Control and Systems Engineering, Modelling and Simulation, Hardware and Architecture, Information Systems, Signal Processing, Theoretical Computer Science
Keywords: Dataflow graphs, Design validation, Models of computation, Signal processing systems
Source: Scopus
Source ID: 84946128443

Research output: Contribution to journalArticleScientificpeer-review

Dominant Rotated Local Binary Patterns (DRLBP) for texture classification

In this paper, we present a novel rotation-invariant and computationally efficient texture descriptor called Dominant Rotated Local Binary Pattern (DRLBP). A rotation invariance is achieved by computing the descriptor with respect to a reference in a local neighborhood. A reference is fast to compute maintaining the computational simplicity of the Local Binary Patterns (LBP). The proposed approach not only retains the complete structural information extracted by LBP, but it also captures the complimentary information by utilizing the magnitude information, thereby achieving more discriminative power. For feature selection, we learn a dictionary of the most frequently occurring patterns from the training images, and discard redundant and non-informative features. To evaluate the performance we conduct experiments on three standard texture datasets: Outex12, Outex 10 and KTH-TIPS. The performance is compared with the state-of-the-art rotation invariant texture descriptors and results show that the proposed method is superior to other approaches.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Signal Processing, Research group: Computational Imaging-CI
Contributors: Mehta, R., Egiazarian, K.
Number of pages: 7
Pages: 16-22
Publication date: 2016
Peer-reviewed: Yes
Early online date: 30 Nov 2015

Publication information

Journal: Pattern Recognition Letters
Volume: 71
ISSN (Print): 0167-8655
Ratings: 
  • Scopus rating (2016): CiteScore 5.2 SJR 0.729 SNIP 1.678
Original language: English
ASJC Scopus subject areas: Software, Artificial Intelligence, Computer Vision and Pattern Recognition, Signal Processing
Keywords: Feature Selection, KTH-TIPS, Local Binary Pattern (LBP), Outex, Rotation Invariance, Texture Classification
Source: Scopus
Source ID: 84951106920

Research output: Contribution to journalArticleScientificpeer-review

Efficiency of texture image filtering and its prediction

Textures are typical elements of natural scene images widely used in pattern recognition and image classification. Noise, often being present in acquired images, deteriorates texture features (characteristics), and it is desirable both to suppress it and to preserve a texture. This task is quite difficult even for the most advanced filters, and the resulting denoising efficiency can be quite low. Due to this, it is desirable to predict a denoising efficiency before filtering to decide whether it is worth filtering a given image or not. In this paper, we analyze several quantitative criteria (metrics) that can characterize filtering efficiency. Prediction strategy is described and its accuracy is studied. Several modern filtering techniques are analyzed and compared. Based on this, practical recommendations are given.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Signal Processing, Kharkiv National Aerospace University, Universite de Rennes, Instituto Politecnico Nacional
Contributors: Rubel, O., Lukin, V., Abramov, S., Vozel, B., Egiazarian, K., Pogrebnyak, O.
Number of pages: 8
Pages: 1543–1550
Publication date: 2016
Peer-reviewed: Yes

Publication information

Journal: Signal, Image and Video Processing
Volume: 10
Issue number: 8
ISSN (Print): 1863-1703
Ratings: 
  • Scopus rating (2016): CiteScore 2.4 SJR 0.373 SNIP 1.118
Original language: English
ASJC Scopus subject areas: Electrical and Electronic Engineering, Signal Processing
Keywords: Filtering efficiency, Image enhancement, Noise suppression, Visual quality
Source: Scopus
Source ID: 84983806396

Research output: Contribution to journalArticleScientificpeer-review

Unbiased Injection of Signal-Dependent Noise in Variance-Stabilized Range

The design, optimization, and validation of many image processing or image-based analysis systems often requires testing of the system performance over a dataset of images corrupted by noise at different signal-to-noise ratio regimes. A noise-free ground-truth image may not be available, and different SNRs are simulated by injecting extra noise into an already noisy image. However, noise in real-world systems is typically signal-dependent, with variance determined by the noise-free image. Thus, also the noise to be injected shall depend on the unknown ground-truth image. To circumvent this issue, we consider the additive injection of noise in variance-stabilized range, where no previous knowledge of the ground-truth signal is necessary. Specifically, we design a special noise-injection operator that prevents the errors on expectation and variance that would otherwise arise when standard variance-stabilizing transformations are used for this task. Thus, the proposed operator is suitable for accurately injecting signal-dependent noise even to images acquired at very low counts.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Signal Processing, Research group: Signal and Image Restoration-RST, Department of Applied Physics
Contributors: Borges, L., Vieira, M., Foi, A.
Pages: 1494-1498
Publication date: 2016
Peer-reviewed: Yes

Publication information

Journal: IEEE Signal Processing Letters
Volume: 23
Issue number: 10
ISSN (Print): 1070-9908
Ratings: 
  • Scopus rating (2016): CiteScore 5.3 SJR 0.798 SNIP 1.806
Original language: English
ASJC Scopus subject areas: Signal Processing, Applied Mathematics, Electrical and Electronic Engineering
Keywords: Anscombe transformation, Noise injection, optimization, Poisson noise, variance stabilization
Electronic versions: 
Source: Scopus
Source ID: 85027556734

Research output: Contribution to journalArticleScientificpeer-review

Using multi-step proposal distribution for improved MCMC convergence in Bayesian network structure learning

Bayesian networks have become popular for modeling probabilistic relationships between entities. As their structure can also be given a causal interpretation about the studied system, they can be used to learn, for example, regulatory relationships of genes or proteins in biological networks and pathways. Inference of the Bayesian network structure is complicated by the size of the model structure space, necessitating the use of optimization methods or sampling techniques, such Markov Chain Monte Carlo (MCMC) methods. However, convergence of MCMC chains is in many cases slow and can become even a harder issue as the dataset size grows. We show here how to improve convergence in the Bayesian network structure space by using an adjustable proposal distribution with the possibility to propose a wide range of steps in the structure space, and demonstrate improved network structure inference by analyzing phosphoprotein data from the human primary T cell signaling network.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Signal Processing, Aalto University, Department of Computer Science and Information Systems
Contributors: Larjo, A., Lähdesmäki, H.
Publication date: 27 Dec 2015
Peer-reviewed: Yes

Publication information

Journal: Eurasip Journal on Bioinformatics and Systems Biology
Volume: 2015
Issue number: 1
Article number: 6
ISSN (Print): 1687-4145
Ratings: 
  • Scopus rating (2015): CiteScore 1.8 SJR 0.314 SNIP 0.371
Original language: English
ASJC Scopus subject areas: Medicine(all), Computer Science(all), Signal Processing, Statistics and Probability, General
Keywords: Bayesian network, MCMC, Proposal distribution, Structure learning

Bibliographical note

EXT="Lähdesmäki, Harri"

Source: Scopus
Source ID: 84932633872

Research output: Contribution to journalArticleScientificpeer-review

Energy cooperation for throughput optimization based on save-then-transmit protocol in wireless communication system

Green communication and energy saving have been a critical issue in modern wireless communication systems. The concepts of energy harvesting and energy transfer are recently receiving much attention in academic research field. In this paper, we study energy cooperation problems based on save-then-transmit protocol and propose two energy cooperation schemes for different system models: two-node communication model and three-node relay communication model. In both models, all of the nodes transmitting information have no fixed energy supplies and gain energy only via wireless energy harvesting from nature. Besides, these nodes also follow a save-then-transmit protocol. Namely, for each timeslot, a fraction (referred to as save-ratio) of time is devoted exclusively to energy harvesting while the remaining fraction is used for data transmission. In order to maximize the system throughput, energy transfer mechanism is introduced in our schemes, i.e., some nodes are permitted to share their harvested energy with other nodes by means of wireless energy transfer. Simulation results demonstrate that our proposed schemes can outperform both the schemes with half-allocate save-ratio and the schemes without energy transfer in terms of throughput performance, and also characterize the dependencies of system throughput, transferred energy, and save-ratio on energy harvesting rate.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Electronics and Communications Engineering, Research group: Wireless Communications and Positioning, Wireless Communications and Positioning (WICO), Chongqing Key Lab of Mobile Communication Technology, Chongqing University of Posts and Telecommunications
Contributors: Dai, C., Li, F., Renfors, M.
Publication date: 26 Dec 2015
Peer-reviewed: Yes

Publication information

Journal: Eurasip Journal on Wireless Communications and Networking
Volume: 2015
Issue number: 1
Article number: 119
ISSN (Print): 1687-1472
Ratings: 
  • Scopus rating (2015): CiteScore 2.7 SJR 0.362 SNIP 1.138
Original language: English
ASJC Scopus subject areas: Computer Networks and Communications, Signal Processing, Computer Science Applications
Keywords: Energy harvesting, Energy transfer, Save-then-transmit protocol, Throughput optimization
Source: Scopus
Source ID: 84930207810

Research output: Contribution to journalArticleScientificpeer-review

Generative part-based Gabor object detector

Discriminative part-based models have become the approach for visual object detection. The models learn from a large number of positive and negative examples with annotated class labels and location (bounding box). In contrast, we propose a part-based generative model that learns from a small number of positive examples. This is achieved by utilizing "privileged information", sparse class-specific landmarks with semantic meaning. Our method uses bio-inspired complex-valued Gabor features to describe local parts. Gabor features are transformed to part probabilities by unsupervised Gaussian Mixture Model (GMM). GMM estimation is robustified for a small amount of data by a randomization procedure inspired by random forests. The GMM framework is also used to construct a probabilistic spatial model of part configurations. Our detector is invariant to translation, rotation and scaling. On part level invariance is achieved by pose quantization which is more efficient than previously proposed feature transformations. In the spatial model, invariance is achieved by mapping parts to an "aligned object space". Using a small number of positive examples our generative method performs comparably to the state-of-the-art discriminative method.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Signal Processing, Research group: Vision, Field robotics for efficient work sites (FIRE), Prostate cancer research center (PCRC), Lappeenranta University of Technology
Contributors: Riabchenko, E., Kämäräinen, J.
Number of pages: 8
Pages: 1-8
Publication date: 15 Dec 2015
Peer-reviewed: Yes

Publication information

Journal: Pattern Recognition Letters
Volume: 68
Issue number: P1
ISSN (Print): 0167-8655
Ratings: 
  • Scopus rating (2015): CiteScore 5.1 SJR 0.95 SNIP 2.002
Original language: English
ASJC Scopus subject areas: Software, Artificial Intelligence, Computer Vision and Pattern Recognition, Signal Processing
Keywords: Gabor feature, Gaussian mixture model, Generative learning, Object detection, Visual classification

Bibliographical note

EXT="Riabchenko, Ekaterina"

Source: Scopus
Source ID: 84941570575

Research output: Contribution to journalArticleScientificpeer-review

Binomial Gaussian mixture filter

In this work, we present a novel method for approximating a normal distribution with a weighted sum of normal distributions. The approximation is used for splitting normally distributed components in a Gaussian mixture filter, such that components have smaller covariances and cause smaller linearization errors when nonlinear measurements are used for the state update. Our splitting method uses weights from the binomial distribution as component weights. The method preserves the mean and covariance of the original normal distribution, and in addition, the resulting probability density and cumulative distribution functions converge to the original normal distribution when the number of components is increased. Furthermore, an algorithm is presented to do the splitting such as to keep the linearization error below a given threshold with a minimum number of components. The accuracy of the estimate provided by the proposed method is evaluated in four simulated single-update cases and one time series tracking case. In these tests, it is found that the proposed method is more accurate than other Gaussian mixture filters found in the literature when the same number of components is used and that the proposed method is faster and more accurate than particle filters.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Automation Science and Engineering, Department of Mathematics, Research group: MAT Positioning, Research group: Positioning, Wireless Communications and Positioning (WICO)
Contributors: Raitoharju, M., Ali-Löytty, S., Piché, R.
Publication date: 2 Dec 2015
Peer-reviewed: Yes

Publication information

Journal: Eurasip Journal on Advances in Signal Processing
Volume: 2015
Issue number: 1
Article number: 36
ISSN (Print): 1687-6172
Ratings: 
  • Scopus rating (2015): CiteScore 2.5 SJR 0.351 SNIP 0.942
Original language: English
ASJC Scopus subject areas: Hardware and Architecture, Signal Processing, Electrical and Electronic Engineering
Keywords: Estimation, Gaussian mixture filter, Nonlinear filtering
Electronic versions: 

Bibliographical note

ORG=ase,0.75
ORG=mat,0.25

Source: Scopus
Source ID: 84934283964

Research output: Contribution to journalArticleScientificpeer-review

A fast universal self-tuned sampler within Gibbs sampling

Bayesian inference often requires efficient numerical approximation algorithms, such as sequential Monte Carlo (SMC) and Markov chain Monte Carlo (MCMC) methods. The Gibbs sampler is a well-known MCMC technique, widely applied in many signal processing problems. Drawing samples from univariate full-conditional distributions efficiently is essential for the practical application of the Gibbs sampler. In this work, we present a simple, self-tuned and extremely efficient MCMC algorithm which produces virtually independent samples from these univariate target densities. The proposal density used is self-tuned and tailored to the specific target, but it is not adaptive. Instead, the proposal is adjusted during an initial optimization stage, following a simple and extremely effective procedure. Hence, we have named the newly proposed approach as FUSS (Fast Universal Self-tuned Sampler), as it can be used to sample from any bounded univariate distribution and also from any bounded multi-variate distribution, either directly or by embedding it within a Gibbs sampler. Numerical experiments, on several synthetic data sets (including a challenging parameter estimation problem in a chaotic system) and a high-dimensional financial signal processing problem, show its good performance in terms of speed and estimation accuracy.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Industrial Management, Research group: Financial Engineering, Research Community on Data-to-Decision (D2D), Universidad Politecnica de Madrid
Contributors: Martino, L., Yang, H., Luengo, D., Kanniainen, J., Corander, J.
Pages: 68-83
Publication date: 1 Dec 2015
Peer-reviewed: Yes

Publication information

Journal: Digital Signal Processing
Volume: 47
ISSN (Print): 1051-2004
Ratings: 
  • Scopus rating (2015): CiteScore 3.3 SJR 0.566 SNIP 1.368
Original language: English
ASJC Scopus subject areas: Signal Processing, Electrical and Electronic Engineering
Keywords: Adaptive rejection Metropolis sampling, Bayesian inference, Gibbs sampling, Markov Chain Monte Carlo (MCMC), Metropolis within Gibbs
Source: Scopus
Source ID: 84948117324

Research output: Contribution to journalArticleScientificpeer-review

Kalman filter with a linear state model for PDR+WLAN positioning and its application to assisting a particle filter

Indoor positioning based on wireless local area network (WLAN) signals is often enhanced using pedestrian dead reckoning (PDR) based on an inertial measurement unit. The state evolution model in PDR is usually nonlinear. We present a new linear state evolution model for PDR. In simulated-data and real-data tests of tightly coupled WLAN-PDR positioning, the positioning accuracy with this linear model is better than with the traditional models when the initial heading is not known, which is a common situation. The proposed method is computationally light and is also suitable for smoothing. Furthermore, we present modifications to WLAN positioning based on Gaussian coverage areas and show how a Kalman filter using the proposed model can be used for integrity monitoring and (re)initialization of a particle filter.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Automation Science and Engineering, Research area: Dynamic Systems, Research group: Positioning, Wireless Communications and Positioning (WICO)
Contributors: Raitoharju, M., Nurminen, H., Piché, R.
Publication date: 1 Dec 2015
Peer-reviewed: Yes

Publication information

Journal: Eurasip Journal on Advances in Signal Processing
Volume: 2015
Issue number: 1
Article number: 33
ISSN (Print): 1687-6172
Ratings: 
  • Scopus rating (2015): CiteScore 2.5 SJR 0.351 SNIP 0.942
Original language: English
ASJC Scopus subject areas: Hardware and Architecture, Signal Processing, Electrical and Electronic Engineering
Keywords: Computational modeling, Indoor positioning, Pedestrian dead reckoning, Wireless LAN
Electronic versions: 
Source: Scopus
Source ID: 84928397748

Research output: Contribution to journalArticleScientificpeer-review

A New Approach to Sign-Bit-Based Parameter Estimation in OFDM Receivers

This article combines algorithm development, thorough analysis and implementation of sign-bit (SB) estimation techniques for symbol timing, carrier frequency offset (CFO) and signal-to-noise ratio (SNR) in orthogonal frequency division multiplexing receivers. The SB estimation is compared in terms of performance and hardware complexity to an equivalent implementation with higher quantization. The techniques are demonstrated by simulation of a SB time/frequency and SB-SNR estimator for 3rd Generation Partnership Project long-term evolution (LTE) cell search in 65-nm technology operating at nominal voltage of 1.2 V. According to post-layout power simulations with toggling information, the architecture estimates the corresponding CFO and SNR for as little as $$479\,\upmu \hbox {W}$$479μW average power for LTE-R8/10, while occupying a silicon area as small as $$0.03\,\hbox {mm}^2$$0.03<sup>mm2</sup>. Even though SB estimation experiences some relative performance penalty when compared to 8-bit quantization, this paper demonstrates various advantages and the potential of employing these techniques in low-complexity terminals.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Electronics and Communications Engineering, Research group: Wireless Communications and Positioning, Wireless Communications and Positioning (WICO), Lund Univ, Lund University, Ericsson Research
Contributors: Diaz, I., Wilhelmsson, L. R., Sofotasios, P. C., Miao, Y., Tan, S., Edfors, O., Öwall, V.
Number of pages: 30
Pages: 3631-3660
Publication date: 23 Nov 2015
Peer-reviewed: Yes

Publication information

Journal: Circuits, Systems and Signal Processing
Volume: 34
Issue number: 11
ISSN (Print): 0278-081X
Ratings: 
  • Scopus rating (2015): CiteScore 2.7 SJR 0.506 SNIP 0.909
Original language: English
ASJC Scopus subject areas: Signal Processing, Applied Mathematics
Keywords: CFO, LTE, OFDM, Receiver design, SNR, Symbol timing, Time synchronization
Source: Scopus
Source ID: 84941992241

Research output: Contribution to journalArticleScientificpeer-review

Robust Inference for State-Space Models with Skewed Measurement Noise

Filtering and smoothing algorithms for linear discrete-time state-space models with skewed and heavy-tailed measurement noise are presented. The algorithms use a variational Bayes approximation of the posterior distribution of models that have normal prior and skew-t-distributed measurement noise. The proposed filter and smoother are compared with conventional low-complexity alternatives in a simulated pseudorange positioning scenario. In the simulations the proposed methods achieve better accuracy than the alternative methods, the computational complexity of the filter being roughly 5 to 10 times that of the Kalman filter.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Automation Science and Engineering, Research group: Positioning, Wireless Communications and Positioning (WICO), Linköping University
Contributors: Nurminen, H., Ardeshiri, T., Piché, R., Gustafsson, F.
Number of pages: 5
Pages: 1898-1902
Publication date: 1 Nov 2015
Peer-reviewed: Yes

Publication information

Journal: IEEE Signal Processing Letters
Volume: 22
Issue number: 11
ISSN (Print): 1070-9908
Ratings: 
  • Scopus rating (2015): CiteScore 4.2 SJR 0.822 SNIP 1.798
Original language: English
ASJC Scopus subject areas: Electrical and Electronic Engineering, Signal Processing, Applied Mathematics
Keywords: Kalman filter, robust filtering, RTS smoother, skew t, skewness, t-distribution, variational Bayes
Electronic versions: 
Source: Scopus
Source ID: 84933056939

Research output: Contribution to journalArticleScientificpeer-review

Entropy and Channel Capacity under Optimum Power and Rate Adaptation over Generalized Fading Conditions

Accurate fading characterization and channel capacity determination are of paramount importance in both conventional and emerging communication systems. The present work addresses the non-linearity of the propagation medium and its effects on the channel capacity. Such fading conditions are first characterized using information theoretic measures, namely, Shannon entropy, cross entropy and relative entropy. The corresponding effects on the channel capacity with and without power adaptation are then analyzed. Closed-form expressions are derived and validated through computer simulations. It is shown that the effects of nonlinearities are significantly larger than those of fading parameters such as the scattered-wave power ratio, and the correlation coefficient between the in-phase and quadrature components in each cluster of multipath components.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Research group: Wireless Communications and Positioning, Department of Electronics and Communications Engineering, Wireless Communications and Positioning (WICO), Department of Electrical Engineering and Computer Science, Aristotle University of Thessaloniki, Department of Electronic Engineering, Khalifa University, Centre for Communication Systems Research, University of Surrey, University of Leeds, International University of Rabat
Contributors: Sofotasios, P. C., Muhaidat, S., Valkama, M., Ghogho, M., Karagiannidis, G. K.
Number of pages: 5
Pages: 2162-2166
Publication date: 1 Nov 2015
Peer-reviewed: Yes

Publication information

Journal: IEEE Signal Processing Letters
Volume: 22
Issue number: 11
ISSN (Print): 1070-9908
Ratings: 
  • Scopus rating (2015): CiteScore 4.2 SJR 0.822 SNIP 1.798
Original language: English
ASJC Scopus subject areas: Electrical and Electronic Engineering, Signal Processing, Applied Mathematics
Keywords: Adaptation policies, channel capacity, entropy
Source: Scopus
Source ID: 84939865476

Research output: Contribution to journalArticleScientificpeer-review

Sparse extreme learning machine classifier exploiting intrinsic graphs

This paper presents an analysis of the recently proposed sparse extreme learning machine (S-ELM) classifier and describes an optimization scheme that can be used to calculate the network output weights. This optimization scheme exploits intrinsic graph structures in order to describe geometric data relationships in the so-called ELM space. Kernel formulations of the approach operating in ELM spaces of arbitrary dimensions are also provided. It is shown that the application of the optimization scheme exploiting geometric data relationships in the original ELM space is equivalent to the application of the original S-ELM to a transformed ELM space. The experimental results show that the incorporation of geometric data relationships in S-ELM can lead to enhanced performance.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Signal Processing, Research Community on Data-to-Decision (D2D), Aristotle University of Thessaloniki, Department of Informatics, Aristotle University of Thessaloniki
Contributors: Iosifidis, A., Tefas, A., Pitas, I.
Number of pages: 5
Pages: 192-196
Publication date: 1 Nov 2015
Peer-reviewed: Yes

Publication information

Journal: Pattern Recognition Letters
Volume: 65
ISSN (Print): 0167-8655
Ratings: 
  • Scopus rating (2015): CiteScore 5.1 SJR 0.95 SNIP 2.002
Original language: English
ASJC Scopus subject areas: Software, Artificial Intelligence, Computer Vision and Pattern Recognition, Signal Processing
Keywords: Intrinsic graphs, Single-hidden layer neural networks, Sparse extreme learning machine
Source: Scopus
Source ID: 84940388000

Research output: Contribution to journalArticleScientificpeer-review

Coupled dictionaries for exemplar-based speech enhancement and automatic speech recognition

Exemplar-based speech enhancement systems work by decomposing the noisy speech as a weighted sum of speech and noise exemplars stored in a dictionary and use the resulting speech and noise estimates to obtain a time-varying filter in the full-resolution frequency domain to enhance the noisy speech. To obtain the decomposition, exemplars sampled in lower dimensional spaces are preferred over the full-resolution frequency domain for their reduced computational complexity and the ability to better generalize to unseen cases. But the resulting filter may be sub-optimal as the mapping of the obtained speech and noise estimates to the full-resolution frequency domain yields a low-rank approximation. This paper proposes an efficient way to directly compute the full-resolution frequency estimates of speech and noise using coupled dictionaries: an input dictionary containing atoms from the desired exemplar space to obtain the decomposition and a coupled output dictionary containing exemplars from the full-resolution frequency domain. We also introduce modulation spectrogram features for the exemplar-based tasks using this approach. The proposed system was evaluated for various choices of input exemplars and yielded improved speech enhancement performances on the AURORA-2 and AURORA-4 databases. We further show that the proposed approach also results in improved word error rates (WERs) for the speech recognition tasks using HMM-GMM and deep-neural network (DNN) based systems.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Signal Processing, Research group: Audio research group, Research Community on Data-to-Decision (D2D), Signal Processing Research Community (SPRC), Speech Processing Research Group, Electrical Engineering Department (ESAT), KU Leuven
Contributors: Baby, D., Virtanen, T., Gemmeke, J. F., Van hamme, H.
Number of pages: 12
Pages: 1788-1799
Publication date: 1 Nov 2015
Peer-reviewed: Yes

Publication information

Journal: Ieee-Acm transactions on audio speech and language processing
Volume: 23
Issue number: 11
ISSN (Print): 2329-9290
Ratings: 
  • Scopus rating (2015): CiteScore 1.6 SJR 1.13 SNIP 1.475
Original language: English
ASJC Scopus subject areas: Signal Processing, Electrical and Electronic Engineering, Media Technology, Acoustics and Ultrasonics, Instrumentation, Linguistics and Language, Speech and Hearing
Keywords: Exemplar-based, Modulation envelope, Noise robust automatic speech recognition, Non-negative sparse coding
Source: Scopus
Source ID: 84942609488

Research output: Contribution to journalArticleScientificpeer-review

Model selection for linear classifiers using Bayesian error estimation

Regularized linear models are important classification methods for high dimensional problems, where regularized linear classifiers are often preferred due to their ability to avoid overfitting. The degree of freedom of the model dis determined by a regularization parameter, which is typically selected using counting based approaches, such as K-fold cross-validation. For large data, this can be very time consuming, and, for small sample sizes, the accuracy of the model selection is limited by the large variance of CV error estimates. In this paper, we study the applicability of a recently proposed Bayesian error estimator for the selection of the best model along the regularization path. We also propose an extension of the estimator that allows model selection in multiclass cases and study its efficiency with L-1 regularized logistic regression and L-2 regularized linear support vector machine. The model selection by the new Bayesian error estimator is experimentally shown to improve the classification accuracy, especially in small sample-size situations, and is able to avoid the excess variability inherent to traditional cross-validation approaches. Moreover, the method has significantly smaller computational complexity than cross-validation. (C) 2015 Elsevier Ltd. All rights reserved.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Signal Processing, Research group: Vision, Research Community on Data-to-Decision (D2D), Universidad Carlos III de Madrid
Contributors: Huttunen, H., Tohka, J.
Number of pages: 10
Pages: 3739-3748
Publication date: Nov 2015
Peer-reviewed: Yes

Publication information

Journal: Pattern Recognition
Volume: 48
Issue number: 11
ISSN (Print): 0031-3203
Ratings: 
  • Scopus rating (2015): CiteScore 8.6 SJR 1.579 SNIP 2.996
Original language: English
ASJC Scopus subject areas: Software, Artificial Intelligence, Computer Vision and Pattern Recognition, Signal Processing
Keywords: Logistic regression, Support vector machine, Regularization, Bayesian error estimator, Linear classifier, MULTINOMIAL LOGISTIC-REGRESSION, SUPPORT VECTOR MACHINES, CLASSIFICATION, PERFORMANCE, BOUNDS

Bibliographical note

EXT="Tohka, Jussi"

Source: Scopus
Source ID: 84937812363

Research output: Contribution to journalArticleScientificpeer-review

Solutions to integrals involving the marcum Q-function and applications

Novel analytic solutions are derived for integrals that involve the generalized Marcum Q -function, exponential functions and arbitrary powers. Simple closed-form expressions are also derived for specific cases of the generic integrals. The offered expressions are both convenient and versatile, which is particularly useful in applications relating to natural sciences and engineering, including wireless communications and signal processing. To this end, they are employed in the derivation of the average probability of detection in energy detection of unknown signals over multipath fading channels as well as of the channel capacity with fixed rate and channel inversion in the case of correlated multipath fading and switched diversity.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Electronics and Communications Engineering, Research group: Wireless Communications and Positioning, Wireless Communications and Positioning (WICO), Department of Electrical and Computer Engineering, Khalifa University, Centrefor Communication Systems Research, Department of Electronic Engineering, University of Surrey, Department of Electrical and Computer Engineering, Aristotle University of Thessaloniki
Contributors: Sofotasios, P. C., Muhaidat, S., Karagiannidis, G. K., Sharif, B. S.
Number of pages: 5
Pages: 1752-1756
Publication date: 1 Oct 2015
Peer-reviewed: Yes

Publication information

Journal: IEEE Signal Processing Letters
Volume: 22
Issue number: 10
ISSN (Print): 1070-9908
Ratings: 
  • Scopus rating (2015): CiteScore 4.2 SJR 0.822 SNIP 1.798
Original language: English
ASJC Scopus subject areas: Electrical and Electronic Engineering, Signal Processing, Applied Mathematics
Source: Scopus
Source ID: 84930225545

Research output: Contribution to journalArticleScientificpeer-review

Adaptive Randomized Coordinate Descent for Sparse Systems: Lasso and Greedy Algorithms

Coordinate descent (CD) is a simple optimization technique suited to low complexity requirements and also for solving large problems. In randomized version, CD was recently shown as very effective for solving least-squares (LS) and other optimization problems. We propose here an adaptive version of randomized coordinate descent (RCD) for finding sparse LS solutions, from which we derive two algorithms, one based on the lasso criterion, the other using a greedy technique. Both algorithms employ a novel way of adapting the probabilities for choosing the coordinates, based on a matching pursuit criterion. Another new feature is that, in the lasso algorithm, the penalty term values are built without knowing the noise level or using other prior information. The proposed algorithms use efficient computations and have a tunable trade-off between complexity and performance through the number of CD steps per time instant. Besides a general theoretical convergence analysis, we present simulations that show good practical behavior, comparable to or better than that of state of the art methods.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Signal Processing, Research group: SGN-SPAG, Signal Processing Research Community (SPRC)
Contributors: Onose, A., Dumitrescu, B.
Number of pages: 11
Pages: 4091-4101
Publication date: 1 Aug 2015
Peer-reviewed: Yes

Publication information

Journal: IEEE Transactions on Signal Processing
Volume: 63
Issue number: 15
ISSN (Print): 1053-587X
Ratings: 
  • Scopus rating (2015): CiteScore 8 SJR 1.581 SNIP 2.687
Original language: English
ASJC Scopus subject areas: Electrical and Electronic Engineering, Signal Processing
Keywords: Adaptive algorithms, coordinate descent, randomization, sparse filters
Source: Scopus
Source ID: 84934311735

Research output: Contribution to journalArticleScientificpeer-review

Adaptive sampling for compressed sensing based image compression

The compressed sensing (CS) theory has been successfully applied to image compression in the past few years as most image signals are sparse in a certain domain. In this paper, we focus on how to improve the sampling efficiency for CS-based image compression by using our proposed adaptive sampling mechanism on the block-based CS (BCS), especially the reweighted one. To achieve this goal, two solutions are developed at the sampling side and reconstruction side, respectively. The proposed sampling mechanism allocates the CS-measurements to image blocks according to the statistical information of each block so as to sample the image more efficiently. A generic allocation algorithm is developed to help assign CS-measurements and several allocation factors derived in the transform domain are used to control the overall allocation in both solutions. Experimental results demonstrate that our adaptive sampling scheme offers a very significant quality improvement as compared with traditional non-adaptive ones.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Signal Processing, Research group: Video, Research Community on Data-to-Decision (D2D), Institute of Image Processing, University of Electronic Science and Technology of China, Hong Kong University of Science and Technology
Contributors: Zhu, S., Zeng, B., Gabbouj, M.
Number of pages: 12
Pages: 94-105
Publication date: 1 Jul 2015
Peer-reviewed: Yes

Publication information

Journal: Journal of Visual Communication and Image Representation
Volume: 30
ISSN (Print): 1047-3203
Ratings: 
  • Scopus rating (2015): CiteScore 3.6 SJR 0.632 SNIP 1.525
Original language: English
ASJC Scopus subject areas: Electrical and Electronic Engineering, Media Technology, Computer Vision and Pattern Recognition, Signal Processing
Keywords: Adaptive sampling, Block-based compressed sensing (BCS), Image coding, Image compression, Measurement allocation, Sampling efficiency, Sparsity Compressed sensing (CS)
Source: Scopus
Source ID: 84926618362

Research output: Contribution to journalArticleScientificpeer-review

Actor Merging for Dataflow Process Networks

Dataflow process networks provide a versatile model of computation for specifying signal processing applications in a platform independent fashion. This attractive feature of dataflow has lately been realized in dataflow programming tools that allow synthesizing the same application specification as both fixed hardware circuits and as software for programmable processors. However, in practice, the specification granularity of the dataflow program remains an arbitrary choice of the designer. Dataflow specifications of the same application with equivalent I/O behaviour can range from a single dataflow actor to a very fine grained network composed of elementary processing operations. A very fine grained dataflow specification might result into a high performance implementation when synthesized as hardware, but might perform poorly when executed on a programmable processor. This article presents actor merging as one solution for this performance portability problem of dataflow programs. In contrast to previous work around actor merging, this article presents a methodology that can merge also dynamic dataflow actors. To support these claims, results of experiments on several processing platforms and application examples ranging from telecommunications to video compression are reported.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Signal Processing Research Community (SPRC), Dept. of Computer Science and Engineering, Univ of Oulu, Abo Akad Univ, Abo Akademi University, Dept Phys, CRPP
Contributors: Boutellier, J., Ersfolk, J., Lilius, J., Mattavelli, M., Roquier, G., Silvén, O.
Number of pages: 13
Pages: 2496-2508
Publication date: 15 May 2015
Peer-reviewed: Yes

Publication information

Journal: IEEE Transactions on Signal Processing
Volume: 63
Issue number: 10
Article number: 7055878
ISSN (Print): 1053-587X
Ratings: 
  • Scopus rating (2015): CiteScore 8 SJR 1.581 SNIP 2.687
Original language: English
ASJC Scopus subject areas: Signal Processing, Electrical and Electronic Engineering
Keywords: Dataflow computing, design automation, signal processing
Source: Scopus
Source ID: 84928152213

Research output: Contribution to journalArticleScientificpeer-review

Spectrum Sensing under RF Non-Linearities: Performance Analysis and DSP-Enhanced Receivers

Intermodulation products arise as a result of low noise amplifier (LNA) and mixer non-linearities in wideband receivers. In the presence of strong blockers, the intermodulation distortion can deteriorate the spectrum sensing performance by causing false alarms and degrading the detection probability. We theoretically analyze the impact of third-order non-linearities on the detection and false alarm probabilities for both energy detectors and cyclostationary detectors under front-end LNA non-linearities. We show that degradation of the detection performance due to nonlinearities of both energy and cyclostationary detection is strongly dependent on the modulation type of the blockers. We then propose two DSP-enhanced receiver architectures to compensate the impact of nonlinearities. The first approach is a post-processing technique which compensates for nonlinearities effect on the test statistic by adapting the sensing time and detection threshold. The second approach is a pre-processing method that compensates by correcting received samples prior to computing the test statistic. This approach is based on adaptively estimating the intermodulation distortion, weighting it by a scalar constant and subtracting it from the subband of interest. We propose a method to adaptively compute the optimal weighting coefficient and show that it depends on the power and modulation of the blockers. Our results show that the pre-processing sample-based compensation method is more effective and that clear dynamic range extension can be obtained by using intermodulation compensation without resorting to increasing the sensing time. We also study the impact of uncertainties about the knowledge or estimates for nonlinearity parameters.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Electronics and Communications Engineering, Research group: Wireless Communications and Positioning, Wireless Communications and Positioning (WICO), Electrical Engineering Department, University of California, Los Angeles (UCLA), Qualcomm Research, Maxlinear
Contributors: Rebeiz, E., Hagh Ghadam, A. S., Valkama, M., Cabric, D.
Number of pages: 15
Pages: 1950-1964
Publication date: 15 Apr 2015
Peer-reviewed: Yes

Publication information

Journal: IEEE Transactions on Signal Processing
Volume: 63
Issue number: 8
ISSN (Print): 1053-587X
Ratings: 
  • Scopus rating (2015): CiteScore 8 SJR 1.581 SNIP 2.687
Original language: English
ASJC Scopus subject areas: Electrical and Electronic Engineering, Signal Processing
Keywords: Cognitive radios, cyclostationary detection, energy detection, intermodulation, nonlinear distortion, nonlinearity compensation, sensing receiver, wideband sensing

Bibliographical note

EXT="Hagh Ghadam, Ali Shahed"

Source: Scopus
Source ID: 84925070855

Research output: Contribution to journalArticleScientificpeer-review

Multiresolution analysis for compactly supported interpolating tensor product wavelets

We construct multidimensional interpolating tensor product multiresolution analyses (MRA's) of the function spaces C<inf>0</inf>(R<sup>n</sup>,K), K = R or K = C, consisting of real or complex valued functions on R<sup>n</sup> vanishing at infinity and the function spaces Cu(R<sup>n</sup>,K) consisting of bounded and uniformly continuous functions on R<sup>n</sup>. We also construct an interpolating dual MRA for both of these spaces. The theory of the tensor products of Banach spaces is used. We generalize the Besov space norm equivalence from the one-dimensional case to our n-dimensional construction.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Physics
Contributors: Höynälänmaa, T.
Number of pages: 36
Publication date: 6 Mar 2015
Peer-reviewed: Yes

Publication information

Journal: International Journal of Wavelets Multiresolution and Information ProcessIng
Volume: 13
Issue number: 2
Article number: 1550010
ISSN (Print): 0219-6913
Ratings: 
  • Scopus rating (2015): CiteScore 1.1 SJR 0.319 SNIP 0.547
Original language: English
ASJC Scopus subject areas: Applied Mathematics, Information Systems, Signal Processing
Keywords: Besov space, injective tensor norm, Interpolating wavelets, multiresolution analysis, multivariate wavelets, projective tensor norm, tensor Product
Source: Scopus
Source ID: 84928923864

Research output: Contribution to journalArticleScientificpeer-review

On the kernel Extreme Learning Machine classifier

In this paper, we discuss the connection of the kernel versions of the ELM classifier with infinite Single-hidden Layer Feedforward Neural networks and show that the original ELM kernel definition can be adopted for the calculation of the ELM kernel matrix for two of the most common activation functions, i.e., the RBF and the sigmoid functions. In addition, we show that a low-rank decomposition of the kernel matrix defined on the input training data can be exploited in order to determine an appropriate ELM space for input data mapping. The ELM space determined from this process can be subsequently used for network training using the original ELM formulation. Experimental results denote that the adoption of the low-rank decomposition-based ELM space determination leads to enhanced performance, when compared to the standard choice, i.e., random input weights generation.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Research Community on Data-to-Decision (D2D), Aristotle University of Thessaloniki, Department of Informatics
Contributors: Iosifidis, A., Tefas, A., Pitas, I.
Number of pages: 7
Pages: 11-17
Publication date: 1 Mar 2015
Peer-reviewed: Yes

Publication information

Journal: Pattern Recognition Letters
Volume: 54
ISSN (Print): 0167-8655
Ratings: 
  • Scopus rating (2015): CiteScore 5.1 SJR 0.95 SNIP 2.002
Original language: English
ASJC Scopus subject areas: Software, Artificial Intelligence, Computer Vision and Pattern Recognition, Signal Processing
Keywords: Extreme learning machine, Infinite networks, Single-hidden layer networks
Source: Scopus
Source ID: 84920068822

Research output: Contribution to journalArticleScientificpeer-review

Image database TID2013: Peculiarities, results and perspectives

This paper describes a recently created image database, TID2013, intended for evaluation of full-reference visual quality assessment metrics. With respect to TID2008, the new database contains a larger number (3000) of test images obtained from 25 reference images, 24 types of distortions for each reference image, and 5 levels for each type of distortion. Motivations for introducing 7 new types of distortions and one additional level of distortions are given; examples of distorted images are presented. Mean opinion scores (MOS) for the new database have been collected by performing 985 subjective experiments with volunteers (observers) from five countries (Finland, France, Italy, Ukraine, and USA). The availability of MOS allows the use of the designed database as a fundamental tool for assessing the effectiveness of visual quality. Furthermore, existing visual quality metrics have been tested with the proposed database and the collected results have been analyzed using rank order correlation coefficients between MOS and considered metrics. These correlation indices have been obtained both considering the full set of distorted images and specific image subsets, for highlighting advantages and drawbacks of existing, state of the art, quality metrics. Approaches to thorough performance analysis for a given metric are presented to detect practical situations or distortion types for which this metric is not adequate enough to human perception. The created image database and the collected MOS values are freely available for downloading and utilization for scientific purposes.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Signal Processing, Research group: Computational Imaging-CI, Research group: Algebraic and Algorithmic Methods in Signal Processing AAMSP, Signal Processing Research Community (SPRC), National Aerospace University, Dept of Transmitters, Receivers and Signal Processing, University of Rennes 1 - IETR, Media Communications Lab, USC Viterbi School of Engineering
Contributors: Ponomarenko, N., Jin, L., Ieremeiev, O., Lukin, V., Egiazarian, K., Astola, J., Vozel, B., Chehdi, K., Carli, M., Battisti, F., Jay Kuo, C. C.
Number of pages: 21
Pages: 57-77
Publication date: 1 Jan 2015
Peer-reviewed: Yes

Publication information

Journal: Signal Processing: Image Communication
Volume: 30
ISSN (Print): 0923-5965
Ratings: 
  • Scopus rating (2015): CiteScore 4 SJR 0.532 SNIP 1.413
Original language: English
ASJC Scopus subject areas: Computer Vision and Pattern Recognition, Signal Processing, Software, Electrical and Electronic Engineering
Keywords: Image denoising, Image lossy compression, Image visual quality metrics
Source: Scopus
Source ID: 84919839405

Research output: Contribution to journalArticleScientificpeer-review

Analytical model in discrete time for cross-layer video communication over LTE

Since video traffic is resource intensive, it is a challenging issue to stream video over low bandwidth networks, whereas video communication over LTE becomes an open research topic nowadays due to LTE’s high throughput capabilities. Indeed, video transmission requires low delay, and wireless channel is time-varying, which result in a scenario when a layer-separated design is replaced by a Cross-Layer Adaptation (CLA) principle. In this paper an efficient analytical model that evaluates the behavior of the downlink LTE channel with CLA is presented. To the best of our knowledge, this is the first time an analytical model using CLA principle has been devised that covers both the transmission process from the eNB to the User Equipment (UE) at the first phase and video decoding process at the UE at the second phase. In order to ensure the cross-layer adaptation in the model, the arrival rate varies based on the received video request, whereas the service probability changes according to the channel quality indicator sent from the UE. In the experimental part the analysis of the main performance measures found from the stationary distribution is conducted.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Signal Processing, Research group: Video, Research Community on Data-to-Decision (D2D), Department of Telecommunication Systems, Peoples’ Friendship University of Russia
Contributors: Efimushkina, T., Gabbouj, M., Samuylov, K.
Number of pages: 13
Pages: 345-357
Publication date: 2015
Peer-reviewed: Yes

Publication information

Journal: Automatic Control and Computer Sciences
Volume: 48
Issue number: 6
ISSN (Print): 0146-4116
Ratings: 
  • Scopus rating (2015): CiteScore 0.4 SJR 0.184 SNIP 0.561
Original language: English
ASJC Scopus subject areas: Signal Processing, Software, Control and Systems Engineering
Keywords: cross-layer adaptation, DASH, downlink, LTE, OFDMA, queuing system, stationary distribution
Source: Scopus
Source ID: 84920176216

Research output: Contribution to journalArticleScientificpeer-review

Digital correction of frequency response mismatches in 2-channel time-interleaved ADCs using adaptive I/Q signal processing

A novel adaptive compensation architecture for the frequency response mismatch of 2-channel time-interleaved ADC (TI-ADC) is proposed for developing high-performance self-adaptive systems. The proposed approach overcomes the existing methods in the sense that the TI-ADC mismatch identification can be performed without allocating a region where only the TI-ADC mismatch spurs are present. This is accomplished via mapping the TI-ADC problem into an I/Q mismatch problem which allows deploying complex statistical signal processing. As proof of concept, the compensation architecture is demonstrated and tested on a 16-bit TI-ADC measured hardware data.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Wireless Communications and Positioning (WICO), Department of Electronics and Communications Engineering, Research group: Wireless Communications and Positioning, Airbus Defense and Space
Contributors: Singh, S., Valkama, M., Epp, M., Anttila, L., Schlecker, W., Ingber, E.
Number of pages: 13
Pages: 543-555
Publication date: 2015
Peer-reviewed: Yes

Publication information

Journal: Analog Integrated Circuits and Signal Processing
Volume: 82
Issue number: 3
ISSN (Print): 0925-1030
Ratings: 
  • Scopus rating (2015): CiteScore 1.2 SJR 0.197 SNIP 0.42
Original language: English
ASJC Scopus subject areas: Surfaces, Coatings and Films, Hardware and Architecture, Signal Processing
Keywords: Circularity, Complex I/Q signal processing, Digitally assisted analog (DASA), Frequency response mismatch identification, Time-interleaved ADC
Source: Scopus
Source ID: 84925535772

Research output: Contribution to journalArticleScientificpeer-review

Subjective evaluation of Super Multi-View compressed contents on high-end light-field 3D displays

Super Multi-View (SMV) video content is composed of tens or hundreds of views that provide a light-field representation of a scene. This representation allows a glass-free visualization and eliminates many causes of discomfort existing in current available 3D video technologies. Efficient video compression of SMV content is a key factor for enabling future 3D video services. This paper first compares several coding configurations for SMV content and several inter-view prediction structures are also tested and compared. The experiments mainly suggest that large differences in coding efficiency can be observed from one configuration to another. Several ratios for the number of coded and synthesized views are compared, both objectively and subjectively. It is reported that view synthesis significantly affects the coding scheme. The amount of views to skip highly depends on the sequence and on the quality of the associated depth maps. Reported ranges of bitrates required to obtain a good quality for the tested SMV content are realistic and coherent with future 4. K/8. K needs. The reliability of the PSNR metric for SMV content is also studied. Objective and subjective results show that PSNR is able to reflect increase or decrease in subjective quality even in the presence of synthesized views. However, depending on the ratio of coded and synthesized views, the order of magnitude of the effective quality variation is biased by PSNR. Results indicate that PSNR is less tolerant to view synthesis artifacts than human viewers. Finally, preliminary observations are initiated. First, the light-field conversion step does not seem to alter the objective results for compression. Secondly, the motion parallax does not seem to be impacted by specific compression artifacts. The perception of the motion parallax is only altered by variations of the typical compression artifacts along the viewing angle, in cases where the subjective image quality is already low. To the best of our knowledge, this paper is the first to carry out subjective experiments and to report results of SMV compression for light-field 3D displays. It provides first results showing that improvement of compression efficiency is required, as well as depth estimation and view synthesis algorithms improvement, but that the use of SMV appears realistic according to next generation compression technology requirements.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Signal Processing, Orange Labs, Holografika Kft., Pamany Peter Katolikus Egyetem
Contributors: Dricot, A., Jung, J., Cagnazzo, M., Pesquet, B., Dufaux, F., Kovács, P., Adhikarla, V. K.
Pages: 369–385
Publication date: 2015
Peer-reviewed: Yes

Publication information

Journal: Signal Processing: Image Communication
Volume: 39
Issue number: Part B
ISSN (Print): 0923-5965
Ratings: 
  • Scopus rating (2015): CiteScore 4 SJR 0.532 SNIP 1.413
Original language: English
ASJC Scopus subject areas: Computer Vision and Pattern Recognition, Signal Processing, Software, Electrical and Electronic Engineering
Keywords: 3D, Light-field, Subjective evaluation, Super Multi-View, Video coding, Video compression
Source: Scopus
Source ID: 84947865722

Research output: Contribution to journalArticleScientificpeer-review

Non-negative tensor factorization models for Bayesian audio processing

We provide an overview of matrix and tensor factorization methods from a Bayesian perspective, giving emphasis on both the inference methods and modeling techniques. Factorization based models and their many extensions such as tensor factorizations have proved useful in a broad range of applications, supporting a practical and computationally tractable framework for modeling. Especially in audio processing, tensor models help in a unified manner the use of prior knowledge about signals, the data generation processes as well as available data from different modalities. After a general review of tensor models, we describe the general statistical framework, give examples of several audio applications and describe modeling strategies for key problems such as deconvolution, source separation, and transcription.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Signal Processing, Research group: Audio research group, Research Community on Data-to-Decision (D2D), Signal Processing Research Community (SPRC), Bogazici Universitesi
Contributors: Şimşekli, U., Virtanen, T., Cemgil, A. T.
Pages: 178–191
Publication date: 2015
Peer-reviewed: Yes

Publication information

Journal: Digital Signal Processing
Volume: 47
ISSN (Print): 1051-2004
Ratings: 
  • Scopus rating (2015): CiteScore 3.3 SJR 0.566 SNIP 1.368
Original language: English
ASJC Scopus subject areas: Signal Processing, Electrical and Electronic Engineering
Keywords: Bayesian audio modeling, Bayesian inference, Coupled factorization, Nonnegative matrix and tensor factorization
Source: Scopus
Source ID: 84948075383

Research output: Contribution to journalArticleScientificpeer-review

Smart home gateway system over Bluetooth low energy with wireless energy transfer capability

As billions of sensors and smart meters connect to the Internet of Things (IoT), current wireless technologies are taking decisive steps to ensure their sustainable operation. One popular IoT scenario features a smart home service gateway, which becomes the central point of user’s home environment facilitating a multitude of tasks. Given that most IoT devices connected to residential gateway are small-scale and battery-powered, the key challenge is to extend their lifetime without recharging/replacing batteries. To this end, a novel radio technology named Bluetooth low energy (BLE) has recently been completed to enable energy-efficient data transfer. Another inspiring innovation is the capability of sensors to harvest wireless energy in their local environment. In this work, we envision a scenario where many in-home sensors are communicating with a smart gateway over the BLE protocol, while at the same time harvesting RF energy transmitted from the gateway wirelessly via a dedicated radio interface. We thoroughly investigate performance limitations of such wireless energy transfer interface (WETI) with dynamic analytical model and with important practical considerations. Our methodology delivers the upper bound on WETI operation coupled with BLE-based communication, which characterizes ultimate system performance over the class of practical radio and energy resource management algorithms.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Department of Electronics and Communications Engineering, Research group: Emerging Technologies for Nano-Bio-Info-Cogno, Wireless Communications and Positioning (WICO), International Insitute for Advanced Aerospace Technologies of St. Petersburg State University of Aerospace Instrumentation
Contributors: Galinina, O., Mikhaylov, K., Andreev, S., Turlikov, A., Koucheryavy, Y.
Publication date: 2015
Peer-reviewed: Yes

Publication information

Journal: Eurasip Journal on Wireless Communications and Networking
Volume: 2015
Issue number: 1
Article number: 178
ISSN (Print): 1687-1472
Ratings: 
  • Scopus rating (2015): CiteScore 2.7 SJR 0.362 SNIP 1.138
Original language: English
ASJC Scopus subject areas: Computer Networks and Communications, Signal Processing, Computer Science Applications
Keywords: Bluetooth low energy, Internet of Things, Sensors, Smart home gateway, Wireless energy transfer
Source: Scopus
Source ID: 84938840129

Research output: Contribution to journalArticleScientificpeer-review

Class-Specific Reference Discriminant Analysis With Application in Human Behavior Analysis

In this paper, a novel nonlinear subspace learning technique for class-specific data representation is proposed. A novel data representation is obtained by applying nonlinear class-specific data projection to a discriminant feature space, where the data belonging to the class under consideration are enforced to be close to their class representation, while the data belonging to the remaining classes are enforced to be as far as possible from it. A class is represented by an optimized class vector, enhancing class discrimination in the resulting feature space. An iterative optimization scheme is proposed to this end, where both the optimal nonlinear data projection and the optimal class representation are determined in each optimization step. The proposed approach is tested on three problems relating to human behavior analysis: Face recognition, facial expression recognition, and human action recognition. Experimental results denote the effectiveness of the proposed approach, since the proposed class-specific reference discriminant analysis outperforms kernel discriminant analysis, kernel spectral regression, and class-specific kernel discriminant analysis, as well as support vector machine-based classification, in most cases.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Research Community on Data-to-Decision (D2D), Aristotle University of Thessaloniki, Department of Informatics
Contributors: Iosifidis, A., Tefas, A., Pitas, I.
Pages: 315-326
Publication date: 25 Dec 2014
Peer-reviewed: Yes

Publication information

Journal: IEEE Transactions on Human-Machine Systems
Volume: 45
Issue number: 3
ISSN (Print): 2168-2291
Ratings: 
  • Scopus rating (2014): CiteScore 7.3 SJR 1.28 SNIP 3.026
Original language: English
ASJC Scopus subject areas: Artificial Intelligence, Signal Processing, Human Factors and Ergonomics, Computer Networks and Communications, Computer Science Applications, Human-Computer Interaction, Control and Systems Engineering

Research output: Contribution to journalArticleScientificpeer-review

Kernel reference discriminant analysis

Linear Discriminant Analysis (LDA) and its nonlinear version Kernel Discriminant Analysis (KDA) are well-known and widely used techniques for supervised feature extraction and dimensionality reduction. They determine an optimal discriminant space for (non)linear data projection based on certain assumptions, e.g. on using normal distributions (either on the input or in the kernel space) for each class and employing class representation by the corresponding class mean vectors. However, there might be other vectors that can be used for classes representation, in order to increase class discrimination in the resulted feature space. In this paper, we propose an optimization scheme aiming at the optimal class representation, in terms of Fisher ratio maximization, for nonlinear data projection. Compared to the standard approach, the proposed optimization scheme increases class discrimination in the reduced-dimensionality feature space and achieves higher classification rates in publicly available data sets.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Research Community on Data-to-Decision (D2D), Aristotle University of Thessaloniki, Department of Informatics
Contributors: Iosifidis, A., Tefas, A., Pitas, I.
Number of pages: 7
Pages: 85-91
Publication date: 1 Nov 2014
Peer-reviewed: Yes

Publication information

Journal: Pattern Recognition Letters
Volume: 49
ISSN (Print): 0167-8655
Ratings: 
  • Scopus rating (2014): CiteScore 4.3 SJR 0.73 SNIP 2.131
Original language: English
ASJC Scopus subject areas: Software, Artificial Intelligence, Computer Vision and Pattern Recognition, Signal Processing
Keywords: Kernel Discriminant Analysis, Kernel Spectral Regression, Optimized class representation
Source: Scopus
Source ID: 84904957982

Research output: Contribution to journalArticleScientificpeer-review

Discriminant Bag of Words based representation for human action recognition

In this paper we propose a novel framework for human action recognition based on Bag of Words (BoWs) action representation, that unifies discriminative codebook generation and discriminant subspace learning. The proposed framework is able to, naturally, incorporate several (linear or non-linear) discrimination criteria for discriminant BoWs-based action representation. An iterative optimization scheme is proposed for sequential discriminant BoWs-based action representation and codebook adaptation based on action discrimination in a reduced dimensionality feature space where action classes are better discriminated. Experiments on five publicly available data sets aiming at different application scenarios demonstrate that the proposed unified approach increases the codebook discriminative ability providing enhanced action classification performance.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Research Community on Data-to-Decision (D2D), Aristotle University of Thessaloniki, Department of Informatics
Contributors: Iosifidis, A., Tefas, A., Pitas, I.
Number of pages: 8
Pages: 185-192
Publication date: 1 Nov 2014
Peer-reviewed: Yes

Publication information

Journal: Pattern Recognition Letters
Volume: 49
ISSN (Print): 0167-8655
Ratings: 
  • Scopus rating (2014): CiteScore 4.3 SJR 0.73 SNIP 2.131
Original language: English
ASJC Scopus subject areas: Software, Artificial Intelligence, Computer Vision and Pattern Recognition, Signal Processing
Keywords: Bag of Words, Codebook learning, Discriminant learning
Source: Scopus
Source ID: 84907347636

Research output: Contribution to journalArticleScientificpeer-review

Implementation of a high-throughput low-latency polyphase channelizer on GPUs Design and Architectures for Signal and Image Processing 2008

A channelizer is used to separate users or channels in communication systems. A polyphase channelizer is a type of channelizer that uses polyphase filtering to filter, downsample, and downconvert simultaneously. With graphics processing unit (GPU) technology, we propose a novel GPU-based polyphase channelizer architecture that delivers high throughput. This architecture has advantages of providing reduced complexity and optimized parallel processing of many channels, while being configurable via software. This makes our approach and implementation particularly attractive for using GPUs as DSP accelerators for communication systems.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Signal Processing Research Community (SPRC), University of Maryland, Department of Electrical and Computer Engineering
Contributors: Kim, S. C., Bhattacharyya, S. S.
Publication date: 2014
Peer-reviewed: Yes

Publication information

Journal: Eurasip Journal on Advances in Signal Processing
Volume: 2014
Issue number: 1
ISSN (Print): 1687-6172
Ratings: 
  • Scopus rating (2014): CiteScore 2.2 SJR 0.286 SNIP 0.937
Original language: English
ASJC Scopus subject areas: Signal Processing, Hardware and Architecture, Electrical and Electronic Engineering
Keywords: DSP accelerator, GPU front-end receiver, GPU-based radio, Polyphase channelizer, Polyphase filter
Source: Scopus
Source ID: 84907545943

Research output: Contribution to journalArticleScientificpeer-review

Automated design of networks of transport-triggered architecture processors using dynamic dataflow programs

Modern embedded systems show a clear trend towards the use of Multiprocessor System-on-Chip (MPSoC) architectures in order to handle the performance and power consumption constraints. However, the design and validation of dedicated MPSoCs is an extremely hard and expensive task due to their complexity. Thus, the development of automated design processes is of highest importance to satisfy the time-to-market pressure of embedded systems. This paper proposes an automated co-design flow based on the high-level language-based approach of the Reconfigurable Video Coding framework. The designer provides the application description in the RVC-CAL dataflow language, after which the presented co-design flow automatically generates a network of heterogeneous processors that can be synthesized on FPGA chips. The synthesized processors are Very Long Instruction Word-style processors. Such a methodology permits the rapid design of a many-core signal processing system which can take advantage of all levels of parallelism. The toolchain functionality has been demonstrated by synthesizing an MPEG-4 Simple Profile video decoder to two different FPGA boards. The decoder is realized into 18 processors that decode QCIF resolution video at 45 frames per second on a 50 MHz FPGA clock frequency. The results show that the given application can take advantage of every level of parallelism.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Signal Processing Research Community (SPRC), Universite de Rennes, CSE Department, Univ of Oulu, UBL
Contributors: Yviquel, H., Boutellier, J., Raulet, M., Casseau, E.
Number of pages: 8
Pages: 1295-1302
Publication date: Nov 2013
Peer-reviewed: Yes

Publication information

Journal: Signal Processing: Image Communication
Volume: 28
Issue number: 10
ISSN (Print): 0923-5965
Ratings: 
  • Scopus rating (2013): CiteScore 3.2 SJR 0.407 SNIP 1.301
Original language: English
ASJC Scopus subject areas: Software, Signal Processing, Computer Vision and Pattern Recognition, Electrical and Electronic Engineering
Keywords: Co-design, Dataflow programming, Multi-Processor System-on-Chip (MPSoC), Reconfigurable Video Coding (RVC), Transport-Trigger Architecture (TTA)
Source: Scopus
Source ID: 84888203042

Research output: Contribution to journalArticleScientificpeer-review

Towards generic embedded multiprocessing for RVC-CAL dataflow programs

Dataflow languages enable describing signal processing applications in a platform independent fashion, which makes them attractive in today's multiprocessing era. RVC-CAL is a dynamic dataflow language that enables describing complex data-dependent programs such as video decoders. To this date, design automation toolchains for RVC-CAL have enabled creating workstation software, dedicated hardware and embedded application specific multiprocessor implementations out of RVC-CAL programs. However, no solution has been presented for executing RVC-CAL applications on generic embedded multiprocessing platforms. This paper presents a dataflow-based multiprocessor communication model, an architecture prototype that uses it and an automated toolchain for instantiating such a platform and the software for it. The complexity of the platform increases linearly as the number of processors is increased. The experiments in this paper use several instances of the proposed platform, with different numbers of processors. An MPEG-4 video decoder is mapped to the platform and executed on it. Benchmarks are performed on an FPGA board.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Signal Processing Research Community (SPRC), Dept. of Computer Science and Engineering, Univ of Oulu
Contributors: Boutellier, J., Silvén, O.
Number of pages: 6
Pages: 137-142
Publication date: Nov 2013
Peer-reviewed: Yes

Publication information

Journal: Journal of Signal Processing Systems
Volume: 73
Issue number: 2
ISSN (Print): 1939-8018
Ratings: 
  • Scopus rating (2013): CiteScore 2.1 SJR 0.254 SNIP 0.866
Original language: English
ASJC Scopus subject areas: Hardware and Architecture, Information Systems, Signal Processing, Theoretical Computer Science, Control and Systems Engineering, Modelling and Simulation
Keywords: Data flow computing, Design automation, Multiprocessor interconnection
Source: Scopus
Source ID: 84881476500

Research output: Contribution to journalArticleScientificpeer-review

Passive wireless antenna sensor for strain and crack sensing - Electromagnetic modeling, simulation, and testing

This research investigates a passive wireless antenna sensor designed for strain and crack sensing. When the antenna experiences deformation, the antenna shape changes, causing a shift in the electromagnetic resonance frequency of the antenna. A radio frequency identification (RFID) chip is adopted for antenna signal modulation, so that a wireless reader can easily distinguish the backscattered sensor signal from unwanted environmental reflections. The RFID chip captures its operating power from an interrogation electromagnetic wave emitted by the reader, which allows the antenna sensor to be passive (battery-free). This paper first reports the latest simulation results on radiation patterns, surface current density, and electromagnetic field distribution. The simulation results are followed with experimental results on the strain and crack sensing performance of the antenna sensor. Tensile tests show that the wireless antenna sensor can detect small strain changes lower than 20 με, and can perform well at large strains higher than 10 000 με. With a high-gain reader antenna, the wireless interrogation distance can be increased up to 2.1 m. Furthermore, an array of antenna sensors is capable of measuring the strain distribution in close proximity. During emulated crack and fatigue crack tests, the antenna sensor is able to detect the growth of a small crack.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Sensing Systems for Wireless Medicine (MediSense), Georgia Institute of Technology, Georgia Institute of Technology, School of Electrical and Computer Engineering, Virginia Tech
Contributors: Yi, X., Cho, C., Cooper, J., Wang, Y., Tentzeris, M. M., Leon, R. T.
Publication date: Aug 2013
Peer-reviewed: Yes

Publication information

Journal: Smart Materials and Structures
Volume: 22
Issue number: 8
Article number: 085009
ISSN (Print): 0964-1726
Ratings: 
  • Scopus rating (2013): CiteScore 4.4 SJR 1.006 SNIP 1.93
Original language: English
ASJC Scopus subject areas: Signal Processing, Atomic and Molecular Physics, and Optics, Civil and Structural Engineering, Materials Science(all), Condensed Matter Physics, Mechanics of Materials, Electrical and Electronic Engineering
Source: Scopus
Source ID: 84881172175

Research output: Contribution to journalArticleScientificpeer-review

Multi-view action recognition based on action volumes, fuzzy distances and cluster discriminant analysis

In this paper, we present a view-independent action recognition method exploiting a low computational-cost volumetric action representation. Binary images depicting the human body during action execution are accumulated in order to produce the so-called action volumes. A novel time-invariant action representation is obtained by exploiting the circular shift invariance property of the magnitudes of the Discrete Fourier Transform coefficients. The similarity of an action volume with representative action volumes is exploited in order to map it to a lower-dimensional feature space that preserves the action class properties. Discriminant learning is, subsequently, employed for further dimensionality reduction and action class discrimination. By using such an action representation, the proposed approach performs fast action recognition. By combining action recognition results coming from different view angles, high recognition rates are obtained. The proposed method is extended to interaction recognition, i.e., to human action recognition involving two persons. The proposed approach is evaluated on a publicly available action recognition database using experimental settings simulating situations that may appear in real-life applications, as well as on a new nutrition support action recognition database.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Research Community on Data-to-Decision (D2D), Aristotle University of Thessaloniki, Department of Informatics
Contributors: Iosifidis, A., Tefas, A., Pitas, I.
Number of pages: 13
Pages: 1445-1457
Publication date: Jun 2013
Peer-reviewed: Yes

Publication information

Journal: Signal Processing
Volume: 93
Issue number: 6
ISSN (Print): 0165-1684
Ratings: 
  • Scopus rating (2013): CiteScore 5.1 SJR 0.909 SNIP 2.244
Original language: English
ASJC Scopus subject areas: Electrical and Electronic Engineering, Control and Systems Engineering, Software, Signal Processing, Computer Vision and Pattern Recognition
Keywords: Action recognition, Action volumes, Cluster discriminant analysis, Fuzzy vector quantization
Source: Scopus
Source ID: 84875267100

Research output: Contribution to journalArticleScientificpeer-review

Integration of dataflow-based heterogeneous multiprocessor scheduling techniques in GNU radio

As the variety of off-the-shelf processors expands, traditional implementation methods of systems for digital signal processing and communication are no longer adequate to achieve design objectives in a timely manner. There is a necessity for designers to easily track the changes in computing platforms, and apply them efficiently while reusing legacy code and optimized libraries that target specialized features in single processing units. In this context, we propose an integration workflow to schedule and implement Software Defined Radio (SDR) protocols that are developed using the GNU Radio environment on heterogeneous multiprocessor platforms. We show how to utilize Single Instruction Multiple Data (SIMD) units provided in Graphics Processing Units (GPUs) along with vector accelerators implemented in General Purpose Processors (GPPs). We augment a popular SDR framework (i.e, GNU Radio) with a library that seamlessly allows offloading of algorithm kernels mapped to the GPU without changing the original protocol description. Experimental results show how our approach can be used to efficiently explore design spaces for SDR system implementation, and examine the overhead of the integrated backend (software component) library.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Signal Processing Research Community (SPRC), University of Maryland, Department of Electrical and Computer Engineering, Virginia Tech, Laboratory for Telecommunications Sciences
Contributors: Zaki, G. F., Plishker, W., Bhattacharyya, S. S., Clancy, C., Kuykendall, J.
Number of pages: 15
Pages: 177-191
Publication date: Feb 2013
Peer-reviewed: Yes

Publication information

Journal: Journal of Signal Processing Systems
Volume: 70
Issue number: 2
ISSN (Print): 1939-8018
Ratings: 
  • Scopus rating (2013): CiteScore 2.1 SJR 0.254 SNIP 0.866
Original language: English
ASJC Scopus subject areas: Control and Systems Engineering, Theoretical Computer Science, Signal Processing, Information Systems, Modelling and Simulation, Hardware and Architecture
Keywords: Design methodology, GNU Radio, Graphic processor unit, Multiprocessor scheduling, Software defined radio
Source: Scopus
Source ID: 84892800816

Research output: Contribution to journalArticleScientificpeer-review

Dynamic action recognition based on dynemes and Extreme Learning Machine

In this paper, we propose a novel method that performs dynamic action classification by exploiting the effectiveness of the Extreme Learning Machine (ELM) algorithm for single hidden layer feedforward neural networks training. It involves data grouping and ELM based data projection in multiple levels. Given a test action instance, a neural network is trained by using labeled action instances forming the groups that reside to the test sample's neighborhood. The action instances involved in this procedure are, subsequently, mapped to a new feature space, determined by the trained network outputs. This procedure is performed multiple times, which are determined by the test action instance at hand, until only a single class is retained. Experimental results denote the effectiveness of the dynamic classification approach, compared to the static one, as well as the effectiveness of the ELM in the proposed dynamic classification setting.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Research Community on Data-to-Decision (D2D), Aristotle University of Thessaloniki, Department of Informatics
Contributors: Iosifidis, A., Tefas, A., Pitas, I.
Number of pages: 9
Pages: 1890-1898
Publication date: 2013
Peer-reviewed: Yes

Publication information

Journal: Pattern Recognition Letters
Volume: 34
Issue number: 15
ISSN (Print): 0167-8655
Ratings: 
  • Scopus rating (2013): CiteScore 4.8 SJR 0.768 SNIP 2.474
Original language: English
ASJC Scopus subject areas: Software, Artificial Intelligence, Computer Vision and Pattern Recognition, Signal Processing
Keywords: Activity recognition, Dynamic classification, Extreme Learning Machine, Fuzzy vector quantization
Source: Scopus
Source ID: 84885069818

Research output: Contribution to journalArticleScientificpeer-review

Automatic hierarchical discovery of quasi-static schedules of RVC-CAL dataflow programs

RVC-CAL is an actor-based dataflow language that enables concurrent, modular and portable description of signal processing algorithms. RVC-CAL programs can be compiled to implementation languages such as C/C++ and VHDL for producing software or hardware implementations. This paper presents a methodology for automatic discovery of piecewise-deterministic (quasi-static) execution schedules for RVC-CAL program software implementations. Quasi-static scheduling moves computational burden from the implementable run-time system to design-time compilation and thus enables making signal processing systems more efficient. The presented methodology divides the RVC-CAL program into segments and hierarchically detects quasi-static behavior from each segment: first at the level of actors and later at the level of the whole segment. Finally, a code generator creates a quasi-statically scheduled version of the program. The impact of segment based quasi-static scheduling is demonstrated by applying the methodology to several RVC-CAL programs that execute up to 58 % faster after applying the presented methodology.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Signal Processing Research Community (SPRC), Dept. of Computer Science and Engineering, Univ of Oulu, UBL
Contributors: Boutellier, J., Raulet, M., Silvén, O.
Number of pages: 6
Pages: 35-40
Publication date: 2013
Peer-reviewed: Yes

Publication information

Journal: Journal of Signal Processing Systems
Volume: 71
Issue number: 1
ISSN (Print): 1939-8018
Ratings: 
  • Scopus rating (2013): CiteScore 2.1 SJR 0.254 SNIP 0.866
Original language: English
ASJC Scopus subject areas: Hardware and Architecture, Information Systems, Signal Processing, Theoretical Computer Science, Control and Systems Engineering, Modelling and Simulation
Keywords: Dataflow analysis, Scheduling, Signal processing
Source: Scopus
Source ID: 84873689972

Research output: Contribution to journalArticleScientificpeer-review

Parameterized scheduling of topological patterns in signal processing dataflow graphs

In recent work, a graphical modeling construct called "topological patterns" has been shown to enable concise representation and direct analysis of repetitive dataflow graph sub-structures in the context of design methods and tools for digital signal processing systems (Sane et al. 2010). In this paper, we present a formal design method for specifying topological patterns and deriving parameterized schedules from such patterns based on a novel schedule model called the scalable schedule tree. The approach represents an important class of parameterized schedule structures in a form that is intuitive for representation and efficient for code generation. Through application case studies involving image processing and wireless communications, we demonstrate our methods for topological pattern representation, scalable schedule tree derivation, and associated dataflow graph code generation.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Signal Processing Research Community (SPRC), University of Maryland, Department of Electrical and Computer Engineering
Contributors: Wang, L. H., Shen, C. C., Wu, S., Bhattacharyya, S. S.
Number of pages: 12
Pages: 275-286
Publication date: 2013
Peer-reviewed: Yes

Publication information

Journal: Journal of Signal Processing Systems
Volume: 71
Issue number: 3
ISSN (Print): 1939-8018
Ratings: 
  • Scopus rating (2013): CiteScore 2.1 SJR 0.254 SNIP 0.866
Original language: English
ASJC Scopus subject areas: Hardware and Architecture, Information Systems, Signal Processing, Theoretical Computer Science, Control and Systems Engineering, Modelling and Simulation
Keywords: Dataflow, Image registration, Scheduling, Software tools, Turbo decoder
Source: Scopus
Source ID: 84879696501

Research output: Contribution to journalArticleScientificpeer-review

Design and synthesis for multimedia systems using the targeted dataflow interchange format

Development of multimedia systems that can be targeted to different platforms is challenging due to the need for rigorous integration between high-level abstract modeling, and low-level synthesis and optimization. In this paper, a new dataflow-based design tool called the targeted dataflow interchange format is introduced for retargetable design, analysis, and implementation of embedded software for multimedia systems. Our approach provides novel capabilities, based on principles of task-level dataflow analysis, for exploring and optimizing interactions across design components; object-oriented data structures for encapsulating contextual information for components; a novel model for representing parameterized schedules that are derived from repetitive graph structures; and automated code generation for programming interfaces and low-level customizations that are geared toward high-performance embedded-processing architectures. We demonstrate our design tool for cross-platform application design, parameterized schedule representation, and associated dataflow graph-code generation using a case study centered around an image registration application.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Signal Processing Research Community (SPRC), University of Maryland, SAIC, New Jersey Institute of Technology, Department of Electrical and Computer Engineering
Contributors: Shen, C. C., Wu, S., Sane, N., Wu, H. H., Plishker, W., Bhattacharyya, S. S.
Number of pages: 11
Pages: 630-640
Publication date: 2012
Peer-reviewed: Yes

Publication information

Journal: IEEE Transactions on Multimedia
Volume: 14
Issue number: 3 PART1
Article number: 6172244
ISSN (Print): 1520-9210
Ratings: 
  • Scopus rating (2012): CiteScore 5.8 SJR 0.815 SNIP 2.573
Original language: English
ASJC Scopus subject areas: Signal Processing, Media Technology, Computer Science Applications, Electrical and Electronic Engineering
Keywords: Dataflow graphs, design tools, embedded signal processing, scheduling, software synthesis
Source: Scopus
Source ID: 84861152678

Research output: Contribution to journalArticleScientificpeer-review

Mapping parameterized cyclo-static dataflow graphs onto configurable hardware

In recent years, parameterized dataflow has evolved as a useful framework for modeling synchronous and cyclo-static graphs in which arbitrary parameters can be changed dynamically. Parameterized dataflow has proven to have significant expressive power for managing dynamics of DSP applications in important ways. However, efficient hardware synthesis techniques for parameterized dataflow representations are lacking. This paper addresses this void; specifically, the paper investigates efficient field programmable gate array (FPGA)-based implementation of parameterized cyclo-static dataflow (PCSDF) graphs. We develop a scheduling technique for throughput-constrained minimization of dataflow buffering requirements when mapping PCSDF representations of DSP applications onto FPGAs. The proposed scheduling technique is integrated with an existing formal schedule model, called the generalized schedule tree, to reduce schedule cost. To demonstrate our new, hardware-oriented PCSDF scheduling technique, we have designed a real-time base station emulator prototype based on a subset of long-term evolution (LTE), which is a key cellular standard.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Signal Processing Research Community (SPRC), National Instruments, University of Maryland, Department of Electrical and Computer Engineering
Contributors: Kee, H., Shen, C. C., Bhattacharyya, S. S., Wong, I., Rao, Y., Kornerup, J.
Number of pages: 17
Pages: 285-301
Publication date: 2012
Peer-reviewed: Yes

Publication information

Journal: Journal of Signal Processing Systems
Volume: 66
Issue number: 3
ISSN (Print): 1939-8018
Ratings: 
  • Scopus rating (2012): CiteScore 2.1 SJR 0.269 SNIP 0.879
Original language: English
ASJC Scopus subject areas: Control and Systems Engineering, Theoretical Computer Science, Signal Processing, Information Systems, Modelling and Simulation, Hardware and Architecture
Keywords: 4G communication systems, Dataflow modeling, FPGA implementation, Parameterized dataflow, Scheduling
Source: Scopus
Source ID: 84888881360

Research output: Contribution to journalArticleScientificpeer-review

Overview of the MPEG reconfigurable video coding framework

Video coding technology in the last 20 years has evolved producing a variety of different and complex algorithms and coding standards. So far the specification of such standards, and of the algorithms that build them, has been done case by case providing monolithic textual and reference software specifications in different forms and programming languages. However, very little attention has been given to provide a specification formalism that explicitly presents common components between standards, and the incremental modifications of such monolithic standards. The MPEG Reconfigurable Video Coding (RVC) framework is a new ISO standard currently under its final stage of standardization, aiming at providing video codec specifications at the level of library components instead of monolithic algorithms. The new concept is to be able to specify a decoder of an existing standard or a completely new configuration that may better satisfy application-specific constraints by selecting standard components from a library of standard coding algorithms. The possibility of dynamic configuration and reconfiguration of codecs also requires new methodologies and new tools for describing the new bitstream syntaxes and the parsers of such new codecs. The RVC framework is based on the usage of a new actor/ dataflow oriented language called CAL for the specification of the standard library and instantiation of the RVC decoder model. This language has been specifically designed for modeling complex signal processing systems. CAL dataflow models expose the intrinsic concurrency of the algorithms by employing the notions of actor programming and dataflow. The paper gives an overview of the concepts and technologies building the standard RVC framework and the non standard tools supporting the RVC model from the instantiation and simulation of the CAL model to software and/or hardware code synthesis.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Signal Processing Research Community (SPRC), Department of Electrical and Computer Engineering, University of Maryland, Ericsson Research, Xilinx Research Labs, CRPP, UBL
Contributors: Bhattacharyya, S. S., Eker, J., Janneck, J. W., Lucarz, C., Mattavelli, M., Raulet, M.
Number of pages: 13
Pages: 251-263
Publication date: May 2011
Peer-reviewed: Yes

Publication information

Journal: Journal of Signal Processing Systems
Volume: 63
Issue number: 2
ISSN (Print): 1939-8018
Ratings: 
  • Scopus rating (2011): CiteScore 1.8 SJR 0.248 SNIP 0.707
Original language: English
ASJC Scopus subject areas: Control and Systems Engineering, Theoretical Computer Science, Signal Processing, Information Systems, Modelling and Simulation, Hardware and Architecture
Keywords: CAL actor language, Code synthesis, Dataflow programming, Reconfigurable Video Coding
Source: Scopus
Source ID: 79954574143

Research output: Contribution to journalArticleScientificpeer-review

Quasi-static scheduling of CAL actor networks for reconfigurable video coding

The upcoming Reconfigurable Video Coding (RVC) standard from MPEG (ISO / IEC SC29WG11) defines a library of coding tools to specify existing or new compressed video formats and decoders. The coding tool library has been written in a dataflow/actor-oriented language named CAL. Each coding tool (actor) can be represented with an extended finite state machine and the data communication between the tools are described as dataflow graphs. This paper proposes an approach to model the CAL actor network with Parameterized Synchronous Data Flow and to derive a quasi-static multiprocessor execution schedule for the system. In addition to proposing a scheduling approach for RVC, an extension to the well-known permutation flow shop scheduling problem that enables rapid run-time scheduling of RVC tasks, is introduced.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Signal Processing Research Community (SPRC), Machine Vision Group, Univ of Oulu, CRPP, Abo Akad Univ, Abo Akademi University, Dept Phys
Contributors: Boutellier, J., Lucarz, C., Lafond, S., Gomez, V. M., Mattavelli, M.
Number of pages: 12
Pages: 191-202
Publication date: May 2011
Peer-reviewed: Yes

Publication information

Journal: Journal of Signal Processing Systems
Volume: 63
Issue number: 2
ISSN (Print): 1939-8018
Ratings: 
  • Scopus rating (2011): CiteScore 1.8 SJR 0.248 SNIP 0.707
Original language: English
ASJC Scopus subject areas: Control and Systems Engineering, Theoretical Computer Science, Signal Processing, Information Systems, Modelling and Simulation, Hardware and Architecture
Keywords: Digital signal processors, Modeling, Parallel processing, Scheduling
Source: Scopus
Source ID: 79954614566

Research output: Contribution to journalArticleScientificpeer-review

Forward simulation and inverse dipole localization with the lowest order Raviart - Thomas elements for electroencephalography

Electroencephalography is a non-invasive imaging modality in which a primary current density generated by the neural activity in the brain is to be reconstructed based on external electric potential measurements. This paper focuses on the finite element method (FEM) from both forward and inverse aspects. The goal is to establish a clear correspondence between the lowest order Raviart-Thomas basis functions and dipole sources as well as to show that the adopted FEM approach is computationally effective. Each basis function is associated with a dipole moment and a location. Four candidate locations are tested. Numerical experiments cover two different spherical multilayer head models, four mesh resolutions and two different forward simulation approaches, one based on FEM and another based on the boundary element method (BEM) with standard dipoles as sources. The forward simulation accuracy is examined through column- and matrix-wise relative errors as well as through performance in inverse dipole localization. A closed-form approximation of dipole potential was used as the reference forward simulation. The present approach is compared to the BEM and indirectly also to the recent FEM-based subtraction approach regarding both accuracy, computation time and accessibility of implementation.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Mathematical modelling with wide societal impact (MathImpact), Aalto University, Dipartimento di Matematica, Università di Genova, University of Warwick, University of Helsinki, CNR-SPIN
Contributors: Pursiainen, S., Sorrentino, A., Campi, C., Piana, M.
Publication date: Apr 2011
Peer-reviewed: Yes

Publication information

Journal: Inverse Problems
Volume: 27
Issue number: 4
Article number: 045003
ISSN (Print): 0266-5611
Ratings: 
  • Scopus rating (2011): CiteScore 3.4 SJR 1.208 SNIP 1.598
Original language: English
ASJC Scopus subject areas: Theoretical Computer Science, Signal Processing, Mathematical Physics, Computer Science Applications, Applied Mathematics
Source: Scopus
Source ID: 79953662770

Research output: Contribution to journalArticleScientificpeer-review

Exploiting statically schedulable regions in dataflow programs

Dataflow descriptions have been used in a wide range of Digital Signal Processing (DSP) applications, such as multi-media processing, and wireless communications. Among various forms of dataflow modeling, Synchronous Dataflow (SDF) is geared towards static scheduling of computational modules, which improves system performance and predictability. However, many DSP applications do not fully conform to the restrictions of SDF modeling. More general dataflow models, such as CAL (Eker and Janneck 2003), have been developed to describe dynamically-structured DSP applications. Such generalized models can express dynamically changing functionality, but lose the powerful static scheduling capabilities provided by SDF. This paper focuses on the detection of SDF-like regions in dynamic dataflow descriptions-in particular, in the generalized specification framework of CAL. This is an important step for applying static scheduling techniques within a dynamic dataflow framework. Our techniques combine the advantages of different dataflow languages and tools, including CAL (Eker and Janneck 2003), DIF (Hsu et al. 2005) and CAL2C (Roquier et al. 2008). In addition to detecting SDF-like regions, we apply existing SDF scheduling techniques to exploit the static properties of these regions within enclosing dynamic dataflow models. Furthermore, we propose an optimized approach for mapping SDF-like regions onto parallel processing platforms such as multi-core processors.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Signal Processing Research Community (SPRC), University of Maryland, Xilinx Research Labs, UBL, Department of Electrical and Computer Engineering
Contributors: Gu, R., Janneck, J. W., Raulet, M., Bhattacharyya, S. S.
Number of pages: 14
Pages: 129-142
Publication date: Apr 2011
Peer-reviewed: Yes

Publication information

Journal: Journal of Signal Processing Systems
Volume: 63
Issue number: 1
ISSN (Print): 1939-8018
Ratings: 
  • Scopus rating (2011): CiteScore 1.8 SJR 0.248 SNIP 0.707
Original language: English
ASJC Scopus subject areas: Control and Systems Engineering, Theoretical Computer Science, Signal Processing, Information Systems, Modelling and Simulation, Hardware and Architecture
Keywords: Cal, Dataflow, DIF, Multicore processors, Quasi-static scheduling
Source: Scopus
Source ID: 79954601701

Research output: Contribution to journalArticleScientificpeer-review

Dimensionality reduction for data visualization

Dimensionality reduction is one of the basic operations in the toolbox of data analysts and designers of machine learning and pattern recognition systems. Given a large set of measured variables but few observations, an obvious idea is to reduce the degrees of freedom in the measurements by representing them with a smaller set of more condensed variables. Another reason for reducing the dimensionality is to reduce computational load in further processing. A third reason is visualization.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Research Community on Data-to-Decision (D2D), Aalto University
Contributors: Kaski, S., Peltonen, J.
Number of pages: 5
Pages: 100-104
Publication date: Mar 2011
Peer-reviewed: Yes

Publication information

Journal: IEEE Signal Processing Magazine
Volume: 28
Issue number: 2
Article number: 5714379
ISSN (Print): 1053-5888
Ratings: 
  • Scopus rating (2011): CiteScore 6.44 SJR 2.164 SNIP 5.875
Original language: English
ASJC Scopus subject areas: Signal Processing, Music, Applied Mathematics, Electrical and Electronic Engineering
Keywords: Data models, Data visualization, Information retrieval, Machine learning, Manifolds, Probabilistic logic, Visualization

Research output: Contribution to journalArticleScientificpeer-review

Topological patterns for scalable representation and analysis of dataflow graphs

Tools for designing signal processing systems with their semantic foundation in dataflow modeling often use high-level graphical user interfaces (GUIs) or text based languages that allow specifying applications as directed graphs. Such graphical representations serve as an initial reference point for further analysis and optimizations that lead to platform-specific implementations. For large-scale applications, the underlying graphs often consist of smaller substructures that repeat multiple times. To enable more concise representation and direct analysis of such substructures in the context of high level DSP specification languages and design tools, we develop the modeling concept of topological patterns, and propose ways for supporting this concept in a high-level language. We augment the dataflow interchange format (DIF) language-a language for specifying DSP-oriented dataflow graphs-with constructs for supporting topological patterns, and we show how topological patterns can be effective in various aspects of embedded signal processing design flows using specific application examples.

General information

Publication status: Published
MoE publication type: A1 Journal article-refereed
Organisations: Signal Processing Research Community (SPRC), University of Maryland, National Instruments, Air Force Research Laboratory Information Directorate, Department of Electrical and Computer Engineering
Contributors: Sane, N., Kee, H., Seetharaman, G., Bhattacharyya, S. S.
Number of pages: 16
Pages: 229-244
Publication date: 2011
Peer-reviewed: Yes

Publication information

Journal: Journal of Signal Processing Systems
Volume: 65
Issue number: 2
ISSN (Print): 1939-8018
Ratings: 
  • Scopus rating (2011): CiteScore 1.8 SJR 0.248 SNIP 0.707
Original language: English
ASJC Scopus subject areas: Control and Systems Engineering, Theoretical Computer Science, Signal Processing, Information Systems, Modelling and Simulation, Hardware and Architecture
Keywords: Dataflow graphs, High-level languages, Model-based design, Signal processing systems, Topological patterns
Source: Scopus
Source ID: 84905269801

Research output: Contribution to journalArticleScientificpeer-review

Modeling and estimation of signal-dependent and correlated noise

The additive white Gaussian noise (AWGN) model is ubiquitous in signal processing. This model is often justified by central-limit theorem (CLT) arguments. However, whereas the CLT may support a Gaussian distribution for the random errors, it does not provide any justification for the assumed additivity and whiteness. As a matter of fact, data acquired in real applications can seldom be described with good approximation by the AWGN model, especially because errors are typically correlated and not additive. Failure to model accurately the noise leads to inaccurate analysis, ineffective filtering, and distortion or even failure in the estimation. This chapter provides an introduction to both signal-dependent and correlated noise and to the relevant models and basic methods for the analysis and estimation of these types of noise. Generic one-parameter families of distributions are used as the essential mathematical setting for the observed signals. The distribution families covered as leading examples include Poisson, mixed Poisson–Gaussian, various forms of signal-dependent Gaussian noise (including multiplicative families and approximations of the Poisson family), as well as doubly censored heteroskedastic Gaussian distributions. We also consider various forms of noise correlation, encompassing pixel and readout cross-talk, fixed-pattern noise, column/row noise, etc., as well as related issues like photo-response and gain nonuniformity. The introduced models and methods are applicable to several important imaging scenarios and technologies, such as raw data from digital camera sensors, various types of radiation imaging relevant to security and to biomedical imaging.

General information

Publication status: Published
MoE publication type: A3 Part of a book or another research book
Organisations: Signal Processing, Research group: Signal and Image Restoration-RST, University of São Paulo
Contributors: Azzari, L., Borges, L. R., Foi, A.
Number of pages: 36
Pages: 1-36
Publication date: 2018

Host publication information

Title of host publication: Denoising of Photographic Images and Video : Fundamentals, Open Challenges and New Trends
Publisher: SPRINGER-VERLAG LONDON LTD
ISBN (Print): 978-3-319-96028-9

Publication series

Name: Advances in Computer Vision and Pattern Recognition
ISSN (Print): 2191-6586
ISSN (Electronic): 2191-6594
ASJC Scopus subject areas: Software, Signal Processing, Computer Vision and Pattern Recognition, Artificial Intelligence
URLs: 
Source: Scopus
Source ID: 85053409603

Research output: Chapter in Book/Report/Conference proceedingChapterScientificpeer-review

Data-driven stream mining systems for computer vision

In this chapter, we discuss the state of the art and future challenges in adaptive stream mining systems for computer vision. Adaptive stream mining in this context involves the extraction of knowledge from image and video streams in real-time, and from sources that are possibly distributed and heterogeneous. With advances in sensor and digital processing technologies, we are able to deploy networks involving large numbers of cameras that acquire increasing volumes of image data for diverse applications in monitoring and surveillance. However, to exploit the potential of such extensive networks for image acquisition, important challenges must be addressed in efficient communication and analysis of such data under constraints on power consumption, communication bandwidth, and end-to-end latency. We discuss these challenges in this chapter, and we also discuss important directions for research in addressing such challenges using dynamic, data-driven methodologies.

General information

Publication status: Published
MoE publication type: A3 Part of a book or another research book
Organisations: Signal Processing Research Community (SPRC), University of Maryland, Electrical Engineering Department, University of California, Los Angeles (UCLA)
Contributors: Bhattacharyya, S. S., Van Der Schaar, M., Atan, O., Tekin, C., Sudusinghe, K.
Number of pages: 16
Pages: 249-264
Publication date: 2014

Host publication information

Title of host publication: Advances in Computer Vision and Pattern Recognition
Volume: 68
Publisher: SPRINGER-VERLAG LONDON LTD

Publication series

Name: Advances in Computer Vision and Pattern Recognition
Volume: 68
ISSN (Print): 21916586
ISSN (Electronic): 21916594
ASJC Scopus subject areas: Software, Signal Processing, Computer Vision and Pattern Recognition, Artificial Intelligence
Source: Scopus
Source ID: 84984919867

Research output: Chapter in Book/Report/Conference proceedingChapterScientificpeer-review

Radio-based Sensing and Indoor Mapping with Millimeter-Wave 5G NR Signals

The emerging 5G New Radio (NR) networks are expected to enable huge improvements, e.g., in terms of capacity, number of connected devices, peak data rates and latency, compared to existing networks. At the same time, a new trend referred to as the RF convergence is aiming to jointly integrate communications and sensing functionalities into the same systems and hardware platforms. In this paper, we investigate the sensing prospects of 5G NR systems, with particular emphasis on the user equipment side and their potential for joint communications and environment mapping. To this end, a radio-based sensing approach utilizing the 5G NR uplink transmit signal and an efficient receiver processing and mapping scheme are proposed. An indoor scenario is then studied and evaluated through real-world RF measurements at 28 GHz mm-wave band, showing that impressive mapping performance can be achieved by the proposed system. The measurement data is available at a permanent open repository.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Electrical Engineering, Research group: Wireless Communications and Positioning, Tampere University
Contributors: Barneto, C. B., Riihonen, T., Turunen, M., Koivisto, M., Talvitie, J., Valkama, M.
Number of pages: 5
Publication date: Jun 2020

Host publication information

Title of host publication: 2020 International Conference on Localization and GNSS, ICL-GNSS 2020 - Proceedings
Publisher: IEEE
Editors: Nurmi, J., Lohan, E., Torres-Sospedra, J., Kuusniemi, H., Ometov, A.
ISBN (Electronic): 9781728164557

Publication series

Name: 2020 International Conference on Localization and GNSS, ICL-GNSS 2020 - Proceedings
ISSN (Electronic): 2325-0771
ASJC Scopus subject areas: Computer Networks and Communications, Signal Processing, Aerospace Engineering, Control and Optimization
Keywords: 5G New Radio (NR), indoor mapping, joint communications and sensing, mm-waves., RF convergence
Source: Scopus
Source ID: 85089434480

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Positioning Based on Noise-Limited Censored Path Loss Data

Positioning is considered one of the most important features and enabler of various novel industry verticals in future radio systems. Since path loss or received signal strength-based measurements are widely available and accessible in the majority of wireless standards, path loss-based positioning has an important role among other positioning technologies. Conventionally path loss-based positioning has two phases; i) fitting a path loss model to training data, if such training data is available, and ii) determining link distance estimates based on the path loss model and calculating the position estimate. However, in both phases, the maximum measurable path loss is limited by measurement noise. Such immeasurable samples are called censored path loss data and such noisy data is commonly neglected in both the model fitting and in the positioning phase. In the case of censored path loss, the loss is known to be above a known threshold level and that information can be used in model fitting as well as in the positioning phase. In this paper, we examine and propose how to use censored path loss data in path loss model-based positioning and demonstrate with simulations the potential of the proposed approach for considerable improvements (over 30%) in positioning accuracy.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Electrical Engineering, Research group: Wireless Communications and Positioning
Contributors: Karttunen, A., Valkama, M., Talvitie, J.
Number of pages: 6
Publication date: Jun 2020

Host publication information

Title of host publication: 2020 International Conference on Localization and GNSS, ICL-GNSS 2020 - Proceedings
Publisher: IEEE
Editors: Nurmi, J., Lohan, E., Torres-Sospedra, J., Kuusniemi, H., Ometov, A.
ISBN (Electronic): 9781728164557

Publication series

Name: 2020 International Conference on Localization and GNSS, ICL-GNSS 2020 - Proceedings
ASJC Scopus subject areas: Computer Networks and Communications, Signal Processing, Aerospace Engineering, Control and Optimization
Keywords: censored data, localization, maximum-likelihood estimation, path loss, path loss model, positioning, probabilistic modeling., shadow fading, wireless networks
Source: Scopus
Source ID: 85089428732

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Modeling and Mitigating 5G Wireless Downlink Interferences for Low-altitude Aerial vehicles

Future 5G networks will serve both terrestrial and aerial users, thanks to their network slicing and flexible numerology capabilities. The probability of Line-of-Sight (LoS) propagation will be intuitively higher for aerial users than for terrestrial users and this will provide a trade-off between increased capacity and increased interference. Our paper analyzes theoretically this trade-off and proposes solutions based on downlink multiantenna beamorming and joint optimization of the signal-to- interference ratio of multiple aerial users. It is shown that Multiple-Input-Single-Output solutions offer the most convenient tradeoff between complexity and capacity/interference performance. Simulation results are provided for mm Wave bands and low-altitude aerial vehicles.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Electrical Engineering, Research group: Wireless Communications and Positioning, Airbus Germany
Contributors: Wang, W., Fath, T., Valkama, M., Lohan, E. S.
Number of pages: 6
Publication date: Jun 2020

Host publication information

Title of host publication: 2020 International Conference on Localization and GNSS, ICL-GNSS 2020 - Proceedings
Publisher: IEEE
Editors: Nurmi, J., Lohan, E., Torres-Sospedra, J., Kuusniemi, H., Ometov, A.
ISBN (Electronic): 9781728164557

Publication series

Name: 2020 International Conference on Localization and GNSS, ICL-GNSS 2020 - Proceedings
ASJC Scopus subject areas: Computer Networks and Communications, Signal Processing, Aerospace Engineering, Control and Optimization
Keywords: autonomous aerial vehicles, communication links, drones, interference, Multiple-Input-Single-Output (MISO), Signal-to-Interference Ratio (SIR)
Source: Scopus
Source ID: 85089441034

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Analog Mitigation of Frequency-Modulated Interference for Improved GNSS Reception

Powerful in-band interference can saturate a receiver's front-end and limit the usefulness of digital interference suppression methods that are bounded by the receiver's limited dynamic range. This is especially true for the self-interference (SI) encountered in full-duplex (FD) radios, but also in the case of strong interference between co-located radios. However, unlike in FD radios, receivers co-located with interference sources do not typically have direct access to the transmitted interference. This work analyzes the performance of a digitally-assisted analog interference mitigation method and its implementation for the suppression of frequency-modulated (FM) interference before quantization in global navigation satellite system (GNSS) receivers that are co-located with interference sources. Over-the-air measurement results are presented that illustrate the effects of interference mitigation on GPS L1 and Galileo E1 reception in a commercial off-the-shelf GNSS receiver and a software-defined GNSS receiver. The analysis covers the effects of the interference mitigation on the radio frequency (RF) front-end, acquisition, tracking, and positioning stages.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Electrical Engineering, Research group: Wireless Communications and Positioning, Rantelon
Contributors: Parlin, K., Riihonen, T.
Number of pages: 6
Publication date: Jun 2020

Host publication information

Title of host publication: 2020 International Conference on Localization and GNSS, ICL-GNSS 2020 - Proceedings
Publisher: IEEE
Editors: Nurmi, J., Lohan, E., Torres-Sospedra, J., Kuusniemi, H., Ometov, A.
ISBN (Electronic): 9781728164557

Publication series

Name: 2020 International Conference on Localization and GNSS, ICL-GNSS 2020 - Proceedings
ASJC Scopus subject areas: Computer Networks and Communications, Signal Processing, Aerospace Engineering, Control and Optimization
Source: Scopus
Source ID: 85089433388

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Adaptive Normalization for Forecasting Limit Order Book Data Using Convolutional Neural Networks

Deep learning models are capable of achieving state-of-the-art performance on a wide range of time series analysis tasks. However, their performance crucially depends on the employed normalization scheme, while they are usually unable to efficiently handle non-stationary features without first appropriately pre-processing them. These limitations impact the performance of deep learning models, especially when used for forecasting financial time series, due to their non-stationary and multimodal nature. In this paper we propose a data-driven adaptive normalization layer which is capable of learning the most appropriate normalization scheme that should be applied on the data. To this end, the proposed method first identifies the distribution from which the data were generated and then it dynamically shifts and scales them in order to facilitate the task at hand. The proposed nor-malization scheme is fully differentiable and it is trained in an end-to-end fashion along with the rest of the parameters of the model. The proposed method leads to significant performance improvements over several competitive normalization approaches, as demonstrated using a large-scale limit order book dataset.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Computing Sciences, Research group: Multimedia Research Group - MRG, Aristotle University of Thessaloniki, Aarhus Universitet
Contributors: Passalis, N., Tefas, A., Kanniainen, J., Gabbouj, M., Iosifidis, A.
Number of pages: 5
Pages: 1713-1717
Publication date: 1 May 2020

Host publication information

Title of host publication: 2020 IEEE International Conference on Acoustics, Speech, and Signal Processing, ICASSP 2020 - Proceedings
Publisher: IEEE
ISBN (Electronic): 9781509066315

Publication series

Name: ICASSP, IEEE International Conference on Acoustics, Speech and Signal Processing - Proceedings
Volume: 2020-May
ISSN (Print): 1520-6149
ASJC Scopus subject areas: Software, Signal Processing, Electrical and Electronic Engineering

Bibliographical note

EXT="Tefas, Anastasios"
EXT="Iosifidis, Alexandros"

Source: Scopus
Source ID: 85089240342

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Peer to Peer Offloading with Delayed Feedback: An Adversary Bandit Approach

Fog computing brings computation and services to the edge of networks enabling real time applications. In order to provide satisfactory quality of experience, the latency of fog networks needs to be minimized. In this paper, we consider a peer computation offloading problem for a fog network with unknown dynamics. Peer competition occurs when different fog nodes offload tasks to the same peer FN. In this paper, the computation offloading problem is modeled as a sequential FN selection problem with delayed feedback. We construct an online learning policy based on the adversary multi-arm bandit framework to deal with peer competition and delayed feedback. Simulation results validate the effectiveness of the proposed policy.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Electrical Engineering, Research group: Wireless Communications and Positioning, Shanghai Advanced Research Institute, Chinese Academy of Sciences, ShanghaiTech University, Shanghai Institute of Microsystem and Information Technology Chinese Academy of Sciences, Peoples’ Friendship University of Russia
Contributors: Yang, M., Zhu, H., Wang, H., Koucheryavy, Y., Samouylov, K., Qian, H.
Number of pages: 5
Pages: 5035-5039
Publication date: 1 May 2020

Host publication information

Title of host publication: 2020 IEEE International Conference on Acoustics, Speech, and Signal Processing, ICASSP 2020 - Proceedings
Publisher: IEEE
ISBN (Electronic): 9781509066315

Publication series

Name: ICASSP, IEEE International Conference on Acoustics, Speech and Signal Processing - Proceedings
Volume: 2020-May
ISSN (Print): 1520-6149
ASJC Scopus subject areas: Software, Signal Processing, Electrical and Electronic Engineering
Keywords: adversary multi-arm bandit, delayed feed-back, Fog computing, reinforcement learning, task offloading
Source: Scopus
Source ID: 85089215773

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

5G new radio evolution towards sub-THz communications

In this paper, the potential of extending 5G New Radio physical layer solutions to support communications in sub-THz frequencies is studied. More specifically, we introduce the status of third generation partnership project studies related to operation on frequencies beyond 52.6 GHz and note also the recent proposal on spectrum horizons provided by federal communications commission (FCC) related to experimental licenses on 95 GHz-3 THz frequency band. Then, we review the power amplifier (PA) efficiency and output power challenge together with the increased phase noise (PN) distortion effect in terms of the supported waveforms. As a practical example on the waveform and numerology design from the perspective of the PN robustness, link performance results using 90 GHz carrier frequency are provided. The numerical results demonstrate that new, higher subcarrier spacings are required to support high throughput, which requires larger changes in the physical layer design. It is also observed that new phase-tracking reference signal designs are required to make the system robust against PN. The results illustrate that single-carrier frequency division multiple access is significantly more robust against PN and can provide clearly larger PA output power than cyclic-prefix orthogonal frequency division multiplexing, and is therefore a highly potential waveform for sub-THz communications.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Electrical Engineering, Research group: Wireless Communications and Positioning, Bell Labs
Contributors: Tervo, O., Levanen, T., Pajukoski, K., Hulkkonen, J., Wainio, P., Valkama, M.
Number of pages: 6
Publication date: 1 Mar 2020

Host publication information

Title of host publication: 2nd 6G Wireless Summit 2020 : Gain Edge for the 6G Era, 6G SUMMIT 2020
Publisher: IEEE
ISBN (Electronic): 9781728160474
ASJC Scopus subject areas: Artificial Intelligence, Hardware and Architecture, Signal Processing, Safety, Risk, Reliability and Quality, Computer Networks and Communications, Instrumentation
Keywords: 5G New Radio, 5G NR, Beyond 5G, DFT-s-OFDM, numerology, OFDM, Phase noise, PHY, physical layer, PN, PTRS, SC-FDMA, Spectrum availability, Sub-THz
Source: Scopus
Source ID: 85086306147

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Protective Coating Methods for Glove-Integrated RFID Tags - A Preliminary Study

In this study, machine washing durability of working glove-integrated passive RFID tags is evaluated. These glove-tags are embedded inside 3D-printed thermoplastic polyurethane platforms. The results are compared to platforms embedded inside brush-painted encapsulant platforms. For a preliminary washing reliability evaluation, both types of glove- integrated platforms are washed in a washing machine for 5 times. Although both platforms can protect glove-tags from the effects of water, the main reliability challenge is found to be the fragile antenna-IC attachments. This paper introduces the two platform materials and the achieved washing test results. These preliminary results determine the future direction of this research: The next step is to study suitable methods to strengthen the interconnections, so that these glove-tags can survive the harsh environment inside a washing machine.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: BioMediTech, Research group: Wireless Identification and Sensing Systems Research Group
Contributors: Khan, Z., He, H., Chen, X., Ukkonen, L., Virkki, J.
Publication date: 1 Mar 2020

Host publication information

Title of host publication: 14th European Conference on Antennas and Propagation, EuCAP 2020
Publisher: IEEE
Article number: 9135632
ISBN (Electronic): 9788831299008

Publication series

Name: 14th European Conference on Antennas and Propagation, EuCAP 2020
ASJC Scopus subject areas: Computer Networks and Communications, Signal Processing, Instrumentation, Radiation
Keywords: Gloves, passive UHF RFID, protective coatings, reliability evaluation, washing
Source: Scopus
Source ID: 85088649095

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Headband Antenna for Wireless Power Transfer to Millimeter-Sized Neural Implants with Minimal Misalignment Effects

We present a headband loop antenna for wireless power transfer to multiple IMDs located in the cranial cavity at the depth of 10 mm from the skin. We characterize the wireless power transfer link in terms of the power gain and the power delivered to the IMD, when maximum SAR compliant transmission power is fed to the headband antenna at frequency of 5 MHz. We also consider two types of the misalignments i.e. lateral and angular, between the IMD antenna and the headband antenna and discuss their impact on the transducer gain, impedance matching and on the power delivered to the IMD.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: BioMediTech, Research group: Wireless Identification and Sensing Systems Research Group
Contributors: Ahmed, S., Sydänheimo, L., Ukkonen, L., Björninen, T.
Number of pages: 4
Publication date: 1 Mar 2020

Host publication information

Title of host publication: 14th European Conference on Antennas and Propagation, EuCAP 2020
Publisher: IEEE
ISBN (Electronic): 9788831299008

Publication series

Name: 14th European Conference on Antennas and Propagation, EuCAP 2020
ASJC Scopus subject areas: Computer Networks and Communications, Signal Processing, Instrumentation, Radiation
Keywords: energy harvesting, implantable antenna, intracranial implants, power transfer efficiency., wireless inductive powering
Source: Scopus
Source ID: 85088647197

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Circularly Polarized Corner-Truncated and Slotted Microstrip Patch Antenna on Textile Substrate for Wearable Passive UHF RFID Tags

We present a compact circularly polarized (CP) antenna for wearable passive UHF RFID tags. The antenna is a square-shaped microstrip patch antenna where we have applied corner truncation and slotting techniques in the top layer conductor for achieving the CP property and a shorting pin and loop structure for impedance matching. Despite using a lowpermittivity textile as antenna substrate, the antenna's footprint size is only 5-by-5 cm, which is approximately 15% of the operating wavelength. At the same time, the on-body measurements, the antenna's axial ratio is 0.9 dB and the measured attainable read range (reader's EIRP =3.28W) of the tag reaches 4.2 meters with a CP reader antenna and ranges from 2.9 meters to 3.4 meters for a linear reader antenna, depending on the rotation angle between the antennas.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: BioMediTech, Research group: Wireless Identification and Sensing Systems Research Group
Contributors: Le, D., Ukkonen, L., Björninen, T.
Number of pages: 5
Publication date: 1 Mar 2020

Host publication information

Title of host publication: 14th European Conference on Antennas and Propagation, EuCAP 2020
Publisher: IEEE
ISBN (Electronic): 9788831299008

Publication series

Name: 14th European Conference on Antennas and Propagation, EuCAP 2020
ASJC Scopus subject areas: Computer Networks and Communications, Signal Processing, Instrumentation, Radiation
Keywords: circular polarization, RFID tag, UHF, wearable antenna
Source: Scopus
Source ID: 85088645766

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Measurements of Reflection and Penetration Losses in Low Terahertz Band Vehicular Communications

The beyond-5G vehicular communications are expected not only to utilize the already explored millimeter-wave band but also to start harnessing the higher frequencies above 100 GHz ultimately targeting the so-called low terahertz band, 300 GHz-1 THz. In this paper, we perform a set of propagation measurements at 300 GHz band in representative vehicular environments. Particularly, we report on the reflection losses from the front, rear, and side of a regular vehicle. In addition, the penetration losses when propagating through, over, and under the vehicle are presented. Our study reveals that the vehicle body is extremely heterogeneous in terms of the propagation losses: the attenuation heavily depends on the trajectory of the 300 GHz signal through the vehicle. The reported measurement data may be used as a reference when developing the vehiclespecific channel and interference models for future wireless communications in the low terahertz band.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Electrical Engineering, Research group: Emerging Technologies for Nano-Bio-Info-Cogno, Technische Universität Braunschweig
Contributors: Petrov, V., Eckhardt, J. M., Moltchanov, D., Koucheryavy, Y., Kurner, T.
Number of pages: 5
Publication date: 1 Mar 2020

Host publication information

Title of host publication: 14th European Conference on Antennas and Propagation, EuCAP 2020
Publisher: Institute of Electrical and Electronics Engineers Inc.
ISBN (Electronic): 9788831299008

Publication series

Name: 14th European Conference on Antennas and Propagation, EuCAP 2020
ASJC Scopus subject areas: Computer Networks and Communications, Signal Processing, Instrumentation, Radiation
Keywords: low terahertz, penetration losses, Propagation measurements, reflection losses, vehicular communications.
Source: Scopus
Source ID: 85088642836

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Towards Asteroid Tomography: Modellings and Measurements Using an Analogue Model

The interior structures of the comets and asteroids, still poorly known, might hold a unique key to understand the early Solar System. Considering the interaction of an illuminated electromagnetic wave with this kind of targets, these 'objects' are very large compared to the applicable wavelength. Consequently, tomographic imaging of such targets, i.e., reconstructing their interior structure via multiple measurements, constitutes a challenging inverse problem. To reach this objective and to develop and test inverse algorithms, we need to investigate electromagnetic fields that have interacted with structures analogous to real asteroids and comets. In this study, we focus on the acquisition of these fields considering three methods: calculated fields obtained with (1) time and (2) frequency domain methods and (3) microwave measurements performed for an analogue model, i.e., a small-scale asteroid model.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Computing Sciences, UMR 7249, G2Elab/Institut Néel
Contributors: Eyraud, C., Sorsa, L. I., Herique, A., Geffrin, J. M., Pursiainen, S., Kofman, W.
Number of pages: 4
Publication date: 1 Mar 2020

Host publication information

Title of host publication: 14th European Conference on Antennas and Propagation, EuCAP 2020
Publisher: IEEE
ISBN (Electronic): 9788831299008

Publication series

Name: 14th European Conference on Antennas and Propagation, EuCAP 2020
ASJC Scopus subject areas: Computer Networks and Communications, Signal Processing, Instrumentation, Radiation
Keywords: 3D inversion, Analogue model, Electromagnetic wave, Large targets, Microwave analogy, Microwave imaging
Source: Scopus
Source ID: 85088663343

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Passive RFID-based Textile Touchpad

This paper presents the first prototype of a passive RFID-based textile touchpad. Our unique solution takes advantage of ICs from passive UHF RFID technology. These components are combined into a textile-integrated IC array, which can be used for handwritten character recognition. As the solution is fully passive and gets all the needed energy from the RFID reader, it enables a maintenance-free and cost-effective user interface that can be integrated into clothing and into textiles around us.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: BioMediTech, Research group: Wireless Identification and Sensing Systems Research Group, Computing Sciences, Research group: Machine Learning Group MLG, Research group: Vision
Contributors: He, H., Chen, X., Raivio, L., Huttunen, H., Virkki, J.
Number of pages: 4
Publication date: 2020

Host publication information

Title of host publication: 14th European Conference on Antennas and Propagation, EuCAP 2020
Publisher: IEEE
Article number: 9135201
ISBN (Print): 978-1-7281-3712-4
ISBN (Electronic): 9788831299008
ASJC Scopus subject areas: Computer Networks and Communications, Signal Processing, Instrumentation, Radiation
Keywords: passive UHF RFID, textile electronics, touchpad, user interface, wearable electronics
Source: Scopus
Source ID: 85088635326

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Constrained PSK: Energy-efficient modulation for Sub-THz systems

Deploying sub-THz frequencies for mobile communications is one timely research area, due to the availability of very wide and contiguous chunks of the radio spectrum. However, at such extremely high frequencies, there are large challenges related to, e.g., phase noise, propagation losses as well as to energy-efficiency, since generating and radiating power with reasonable efficiency is known to be far more difficult than at lower frequencies. To address the energy-efficiency and power amplifier (PA) nonlinear distortion related challenges, modulation methods and waveforms with low peak-to-average-power ratio (PAPR) are needed. To this end, a new modulation approach is formulated and proposed in this paper, referred to as constrained phase-shift keying (CPSK). The CPSK concept builds on the traditional PSK constellations, while additional constraints are applied to the time domain symbol transitions in order to control and reduce the PAPR of the resulting waveform. This new modulation is then compared with pulse-shaped π/2-BPSK and ordinary QPSK, in the discrete Fourier transform (DFT) spread orthogonal frequency division multiplexing (DFT-s-OFDM) context, in terms of the resulting PAPR distributions and the achievable maximum PA output power, subject to constraints in the passband waveform quality and out-of-band emissions. The obtained results show that the proposed CPSK approach allows for reducing the PAPR and thereon for achieving higher PA output powers, compared to QPSK, while still offering the same spectral efficiency. Overall, the CPSK concept offers a flexible modulation solution with controlled PAPR for the future sub-THz networks.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Electrical Engineering, Research group: Wireless Communications and Positioning
Contributors: Nasarre, I. P., Levanen, T., Valkama, M.
Number of pages: 7
Publication date: 2020

Host publication information

Title of host publication: 2020 IEEE International Conference on Communications Workshops, ICC Workshops 2020 - Proceedings
Publisher: IEEE
ISBN (Print): 978-1-7281-7441-9
ISBN (Electronic): 9781728174402

Publication series

Name: IEEE/CIC international conference on communications in China - workshops
ISSN (Print): 2474-9133
ISSN (Electronic): 2474-9141
ASJC Scopus subject areas: Artificial Intelligence, Computer Networks and Communications, Signal Processing, Information Systems and Management, Control and Optimization
Keywords: 5G New Radio (NR) evolution, DFT-s-OFDM, Energy-efficiency, Modulation, PAPR, Power amplifiers, Sub-THz communications

Bibliographical note

JUFOID=88220

Source: Scopus
Source ID: 85090293993

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Reinforcement learning for improved UAV-based integrated access and backhaul operation

There is a strong interest in utilizing commercial cellular networks to support unmanned aerial vehicles (UAVs) to send control commands and communicate heavy traffic. Cellular networks are well suited for offering reliable and secure connections to the UAVs as well as facilitating traffic management systems to enhance safe operation. However, for the full-scale integration of UAVs that perform critical and high-risk tasks, more advanced solutions are required to improve wireless connectivity in mobile networks. In this context, integrated access and backhaul (IAB) is an attractive approach for the UAVs to enhance connectivity and traffic forwarding. In this paper, we study a novel approach to dynamic associations based on reinforcement learning at the edge of the network and compare it to alternative association algorithms. Considering the average data rate, our results indicate that the reinforcement learning methods improve the achievable data rate. The optimal parameters of the introduced algorithm are highly sensitive to the donor next generation node base (DgNB) and UAV IAB node densities, and need to be identified beforehand or estimated via a stateful search. However, its performance nearly converges to that of the ideal scheme with a full knowledge of the data rates in dense deployments of DgNBs.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Electrical Engineering, Research group: Emerging Technologies for Nano-Bio-Info-Cogno, Research group: Wireless Communications and Positioning, Intel Corporation
Contributors: Tafintsev, N., Moltchanov, D., Simsek, M., Yeh, S. P., Andreev, S., Koucheryavy, Y., Valkama, M.
Number of pages: 7
Publication date: 2020

Host publication information

Title of host publication: 2020 IEEE International Conference on Communications Workshops, ICC Workshops 2020 - Proceedings
Publisher: IEEE
ISBN (Print): 978-1-7281-7441-9
ISBN (Electronic): 9781728174402

Publication series

Name: IEEE/CIC international conference on communications in China - workshops
ISSN (Print): 2474-9133
ISSN (Electronic): 2474-9141
ASJC Scopus subject areas: Artificial Intelligence, Computer Networks and Communications, Signal Processing, Information Systems and Management, Control and Optimization

Bibliographical note

JUFOID=88220

Source: Scopus
Source ID: 85090294995

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Comparing capacity gains of static and UAV-based millimeter-wave relays in clustered deployments

The prospective millimeter-wave (mmWave) networks are envisioned to heavily utilize relay nodes to improve their performance in certain scenarios. In addition to the stationary mmWave relays already considered by 3GPP as one of the main focuses, the community recently started to explore the use of unmanned aerial vehicle (UAV)-based mmWave relays. These aerial nodes provide greater flexibility in terms of the relay placement in different environments as well as the ability to optimize the deployment height thus maximizing the cell performance. At the same time, the use of UAV-based relays leads to additional deployment complexity and expenditures for the network operators. In this paper, taking into account 3GPP-standardized mmWave-specific propagation, blockage, and resource allocation we compare the capacity gains brought by the static and the UAV-based mmWave relays in different scenarios. For each of the relay types, we investigate both uniform and clustered distribution of human users. The developed mathematical framework and a numerical study reveal that the highest capacity gains when utilizing the UAV-based relays instead of the static ones are observed in clustered deployments (up to 31%), while the performance difference between the UAV-based and the static mmWave relays under a uniform distribution of users is just 3%.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Electrical Engineering, Research group: Emerging Technologies for Nano-Bio-Info-Cogno, Research group: Wireless Communications and Positioning, Intel Corporation
Contributors: Gapeyenko, M., Petrov, V., Moltchanov, D., Yeh, S. P., Himayat, N., Andreev, S.
Number of pages: 7
Publication date: 2020

Host publication information

Title of host publication: 2020 IEEE International Conference on Communications Workshops, ICC Workshops 2020 - Proceedings
Publisher: IEEE
ISBN (Print): 978-1-7281-7441-9
ISBN (Electronic): 9781728174402

Publication series

Name: IEEE/CIC international conference on communications in China - workshops
ISSN (Print): 2474-9133
ISSN (Electronic): 2474-9141
ASJC Scopus subject areas: Artificial Intelligence, Computer Networks and Communications, Signal Processing, Information Systems and Management, Control and Optimization
Keywords: 5G, MmWave, New Radio, Relay, UAV

Bibliographical note

JUFOID=88220

Source: Scopus
Source ID: 85090293224

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Parametric exploration of cellular swelling in a computational model of cortical spreading depression

Cortical spreading depression (CSD) is a slowly propagating wave of depolarization of brain cells, followed by temporary silenced electrical brain activity. Major structural changes during CSD are linked to neuronal and possibly glial swelling. However, basic questions still remain unanswered. In particular, there are open questions regarding whether neurons or glial cells swell more, and how the cellular swelling affects the CSD wave propagation.In this study, we computationally explore how different parameters affect the swelling of neurons and astrocytes (starshaped glial cells) during CSD and how the cell swelling alters the CSD wave spatial distribution. We apply a homogenized mathematical model that describes electrodiffusion in the intraand extracellular space, and discretize the equations using a finite element method. The simulations are run with a twocompartment (extracellular space and neurons) and a threecompartment version of the model with astrocytes added. We consider cell swelling during CSD in four scenarios: (A) incorporating aquaporin-4 channels in the astrocytic membrane, (B) increasing the neuron/astrocyte ratio to 2:1, (C) blocking and increasing the Na+/K+-ATPase rate in the astrocytic compartment, and (D) blocking the Cl- channels in astrocytes. Our results show that increasing the water permeability in the astrocytes results in a higher astrocytic swelling and a lower neuronal swelling than in the default case. Further, elevated neuronal density increases the swelling in both neurons and astrocytes. Blocking the Na+/K+-ATPase in the astrocytes leads to an increased wave width and swelling in both compartments, which instead decreases when the pump rate is raised. Blocking the Cl- channels in the astrocytes results in neuronal swelling, and a shrinkage in the astrocytes. Our results suggest a supporting role of astrocytes in preventing cellular swelling and CSD, as well as highlighting how dysfunctions in astrocytes might elicit CSD.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: BioMediTech, Research group: Computational Biophysics and Imaging Group, Centre for Molecular Medicine Norway, Nordic European Molecular Biology Laboratory Partnership, University of Oslo, University of California San Diego, Simula Research Laboratory
Contributors: Genocchi, B., Cunha, A., Jain, S., Hyttinen, J., Lenk, K., Ellingsrud, A. J.
Number of pages: 5
Pages: 2491-2495
Publication date: 2020

Host publication information

Title of host publication: 42nd Annual International Conferences of the IEEE Engineering in Medicine and Biology Society : Enabling Innovative Technologies for Global Healthcare, EMBC 2020
Publisher: IEEE
ISBN (Print): 978-1-7281-1991-5
ISBN (Electronic): 9781728119908

Publication series

Name: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
Volume: 2020-July
ISSN (Electronic): 1558-4615
ASJC Scopus subject areas: Signal Processing, Biomedical Engineering, Computer Vision and Pattern Recognition, Health Informatics
Source: Scopus
Source ID: 85091006468

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Prototyping directional UAV-based wireless access and backhaul systems

Providing sufficient mobile coverage during mass public events or critical situations is a highly challenging task for the network operators. To fulfill the extreme capacity and coverage demands within a limited area, several augmenting solutions might be used. Among them, novel technologies like a fleet of compact base stations mounted on Unmanned Aerial Vehicles (UAVs) are gaining momentum because of their time- and cost- efficient deployment. Despite the fact that the concept of aerial wireless access networks has been investigated recently in many research studies, there are still numerous practical aspects that require further understanding and extensive evaluation. Taking this as a motivation, in this paper, we develop the concept of continuous wireless coverage provisioning by the means of UAVs and assess its usability in mass scenarios with thousands of users. With our system-level simulations as well as a measurement campaign, we take into account a set of important parameters including weather conditions, UAV speed, weight, power consumption, and millimeter- wave (mmWave) antenna configuration. As a result, we provide more realistic data about the performance of the access and backhaul links together with the practical lessons learned about the design and real-world applicability of the UAV-enabled wireless access networks.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Electrical Engineering, Department of Telecommunications, Brno University of Technology
Contributors: Gerasimenko, M., Pokorny, J., Schneider, T., Sirjov, J., Andreev, S., Hosek, J.
Publication date: 1 Dec 2019

Host publication information

Title of host publication: 2019 IEEE Global Communications Conference, GLOBECOM 2019 - Proceedings
Publisher: IEEE
Article number: 9014228
ISBN (Electronic): 9781728109626
ASJC Scopus subject areas: Computer Networks and Communications, Hardware and Architecture, Information Systems, Signal Processing, Information Systems and Management, Safety, Risk, Reliability and Quality, Media Technology, Health Informatics

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Optimized wake-up scheme with bounded delay for energy-efficient MTC

The limitations of state-of-the-art cellular modems prevent achieving low-power and low-latency Machine Type Communications (MTC) based on current power saving mechanisms alone. Recently, the concept of wake-up scheme has been proposed to enhance battery lifetime of 5G devices, while reducing the buffering delay. The existing wake-up algorithms use static operational parameters that are determined by the radio access network at the start of the userâ™s session. In this paper, the average power consumption of the wake-up enabled MTC UE is modeled by using a semi-Markov process and then optimized through a delay-constrained optimization problem, by which the optimal wake-up cycle is obtained in closed form. Numerical results show that the proposed solution reduces the power consumption of an optimized Discontinuous Reception (DRX) scheme by up to 40% for a given delay requirement.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Electrical Engineering, Helsinki RanD Center, Huawei Technologies Oy (Finland). Co. Ltd., Centre Tecnologic de Telecomunicacions de Catalunya
Contributors: Rostami, S., Lagen, S., Costa, M., DIni, P., Valkama, M.
Publication date: 1 Dec 2019

Host publication information

Title of host publication: 2019 IEEE Global Communications Conference, GLOBECOM 2019 - Proceedings
Publisher: IEEE
Article number: 9013534
ISBN (Electronic): 9781728109626
ASJC Scopus subject areas: Computer Networks and Communications, Hardware and Architecture, Information Systems, Signal Processing, Information Systems and Management, Safety, Risk, Reliability and Quality, Media Technology, Health Informatics
Keywords: 5G, DRX, Energy efficiency, MTC, Wake-up schemes

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Gamified coding: Toy robots and playful learning in early education

This paper explores the activity of coding with smart toy robots Dash and Botley as a part of playful learning in the Finnish early education context. The findings of our study demonstrate how coding with the two toy robots was approached, conducted and played by Finnish preschoolers aged 5-6 years. The main conclusion of the study is that preschoolers used the toy robots with affordances related to coding mainly in developing gamified play around them by designing tracks for the toys, programming the toys to solve obstacle paths, and competing in player-generated contests of dexterity, speed and physically mobile play.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Computing Sciences, Research group: TUT Game Lab, University of Turku School of Cultural Production and Landscape Studies, Prizztech Ltd.
Contributors: Heljakka, K., Ihamaki, P., Tuomi, P., Saarikoski, P.
Number of pages: 6
Pages: 800-805
Publication date: 1 Dec 2019

Host publication information

Title of host publication: Proceedings - 6th Annual Conference on Computational Science and Computational Intelligence, CSCI 2019
Publisher: IEEE
Article number: 9071010
ISBN (Electronic): 9781728155845
ASJC Scopus subject areas: Artificial Intelligence, Computer Networks and Communications, Signal Processing, Hardware and Architecture, Computational Theory and Mathematics
Keywords: Coding, Gamification, Physical play, Programming, Toy robots
Source: Scopus
Source ID: 85084738629

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

V2X Connectivity: From LTE to Joint Millimeter Wave Vehicular Communications and Radar Sensing

To meet the prospective demands of intelligent transportation systems (ITS), the Release 14 (Rel-14) and Rel-15 of the Long Term Evolution (LTE) specifications include solutions for enhanced vehicle-to-everything (V2X) communications. While the technical enablers of Rel-14 are suitable for delivering basic safety messages, Rel-15 supports more demanding ITS services with stringent latency and reliability. Starting in Rel-15 and continuing in Rel-16, the 3GPP was developing a novel radio interface for 5G systems, termed the New Radio (NR), which will enable ultra reliable and low latency communications suitable even for the most demanding ITS applications. In this paper, we overview the new V2X-specific features in Rel-15 and Rel-16. Further, we argue that future V2X and automotive radar systems may reuse common equipment, such as millimeter-wave antenna arrays. We finally discuss the vision of joint vehicular communications and radar sensing as well as characterize unified channel access for millimeter-wave vehicular communications and radar sensing.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Electrical Engineering, Research group: Emerging Technologies for Nano-Bio-Info-Cogno, Ericsson Research, Ericsson Research, Kungliga Tekniska Högskolan KTH
Contributors: Petrov, V., Fodor, G., Andreev, S., Do, H., Sahlin, H.
Number of pages: 5
Pages: 1120-1124
Publication date: Nov 2019

Host publication information

Title of host publication: Conference Record - 53rd Asilomar Conference on Circuits, Systems and Computers, ACSSC 2019
Publisher: IEEE Computer Society
Editor: Matthews, M. B.
Article number: 9048846
ISBN (Electronic): 9781728143002

Publication series

Name: Conference Record - Asilomar Conference on Signals, Systems and Computers
Volume: 2019-November
ISSN (Print): 1058-6393
ASJC Scopus subject areas: Signal Processing, Computer Networks and Communications
Source: Scopus
Source ID: 85083343528

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Closed-Loop DPD for Digital MIMO Transmitters under Antenna Crosstalk

Due to the closely-spaced antenna elements in largearray or massive MIMO transmitters, antenna crosstalk is inevitable. This imposes additional challenges when seeking to linearize the power amplifiers at the transmitter through digital predistortion (DPD). In the commonly applied indirect learning architecture (ILA), the antenna crosstalk is known to result in a large amount of additional basis functions (BFs) in order to account for all the coupling signal terms and achieve good linearization. In this article, we propose a novel closed-loop DPD architecture and associated parameter learning algorithms that can provide efficient linearization of digital MIMO transmitters under antenna crosstalk. The proposed solution does not need extra basis functions, and is thus shown to provide large benefits in terms of computational complexity compared to existing state-of-the-art. Comprehensive numerical results are also provided, showing excellent linearization performance outperforming the existing reference methods.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Electrical Engineering, Research group: Wireless Communications and Positioning
Contributors: Brihuega, A., Abdelaziz, M., Anttila, L., Barneto, C. B., Valkama, M.
Number of pages: 8
Pages: 1682-1689
Publication date: Nov 2019

Host publication information

Title of host publication: Conference Record - 53rd Asilomar Conference on Circuits, Systems and Computers, ACSSC 2019
Publisher: IEEE Computer Society
Editor: Matthews, M. B.
Article number: 9049001
ISBN (Electronic): 9781728143002

Publication series

Name: Conference Record - Asilomar Conference on Signals, Systems and Computers
Volume: 2019-November
ISSN (Print): 1058-6393
ASJC Scopus subject areas: Signal Processing, Computer Networks and Communications
Keywords: Antenna arrays, antenna crosstalk, closed-loop systems, digital predistortion, nonlinear distortion, power amplifier
Source: Scopus
Source ID: 85083287470

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Fast fourier color constancy and grayness index for ISPA illumination estimation challenge

We briefly introduce two submissions to the Illumination Estimation Challenge, in the Int'l Workshop on Color Vision, affiliated to the 11th Int'l Symposium on Image and Signal Processing and Analysis. The fourier-transform-based submission is ranked 3rd, and the statistical Gray-pixel-based one ranked 6th.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Computing Sciences, South China University of Technology
Contributors: Qian, Y., Chen, K., Yu, H.
Number of pages: 3
Pages: 352-354
Publication date: 17 Oct 2019

Host publication information

Title of host publication: ISPA 2019 - 11th International Symposium on Image and Signal Processing and Analysis
Publisher: IEEE
Editors: Loncaric, S., Bregovic, R., Carli, M., Subasic, M.
ISBN (Electronic): 9781728131405

Publication series

Name: International Symposium on Image and Signal Processing and Analysis, ISPA
Volume: 2019-September
ISSN (Print): 1845-5921
ISSN (Electronic): 1849-2266
ASJC Scopus subject areas: Computational Theory and Mathematics, Computer Graphics and Computer-Aided Design, Computer Vision and Pattern Recognition, Signal Processing
Keywords: Color constancy, FFCC, Gray pixel, Illumination

Bibliographical note

EXT="Chen, Ke"

Source: Scopus
Source ID: 85074428933

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Towards Algebraic Modeling of GPU Memory Access for Bank Conflict Mitigation

Graphics Processing Units (GPU) have been widely used in various fields of scientific computing, such as in signal processing. GPUs have a hierarchical memory structure with memory layers that are shared between GPU processing elements. Partly due to the complex memory hierarchy, GPU programming is non-Trivial, and several aspects must be taken into account, one being memory access patterns. One of the fastest GPU memory layers, shared memory, is grouped into banks to enable fast, parallel access for processing elements. Unfortunately, it may happen that multiple threads of a GPU program may access the same shared memory bank simultaneously causing a bank conflict. If this happens, program execution slows down as memory accesses have to be rescheduled to determine which instruction to execute first. Bank conflicts are not taken into account automatically by the compiler, and hence the programmer must detect and deal with them prior to program execution. In this paper, we present an algebraic approach to detect bank conflicts and prove some theoretical results that can be used to predict when bank conflicts happen and how to avoid them. Also, our experimental results illustrate the savings in computation time.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Computing Sciences, Research area: Computer engineering, Tampere University
Contributors: Ferranti, L., Boutellier, J.
Number of pages: 6
Pages: 103-108
Publication date: 1 Oct 2019

Host publication information

Title of host publication: 2019 IEEE International Workshop on Signal Processing Systems, SiPS 2019
Publisher: IEEE
ISBN (Electronic): 9781728119274
ASJC Scopus subject areas: Electrical and Electronic Engineering, Signal Processing, Applied Mathematics, Hardware and Architecture
Keywords: block matching, Graphics processing units, memory hierarchy, OpenCL

Bibliographical note

INT=comp,"Ferranti, Luca"

Source: Scopus
Source ID: 85082393531

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

A perspective on wireless M-bus for smart electricity grids

The Internet of Things (IoT) enables long-range outdoor networks, such as smart grid and municipal lighting, as well as short-range indoor systems for smart homes, residential security, and energy management. Wireless connectivity and standardized communication protocols become an essential technology baseline for these diverse IoT applications. The focus of this work is wireless connectivity for smart metering systems. One of the recent protocols in this field is Wireless M-BUS, which is being widely utilized for remote metering applications across Europe. Therefore, in this paper, we detail a novel multi-platform framework designed to serve as a data generator for the protocol in question. The developed software allows to construct Wireless M-Bus telegrams with a high level of detail according to the EN 13757-4 specification and then schedule them for periodic transmission. The evaluation of the data generator is done in real scenario by using previously developed prototype equipped with IQRF TR72DA communication module acting as a smart meter with implemented software framework. As a result, the evaluation of communication distance between the developed Wireless MBus prototype and commercial gateway was tested in case of indoor scenario at Brno University of Technology, Faculty of Electrical Engineering and Communication.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Electrical Engineering, Brno University of Technology, Department of Telecommunication
Contributors: Masek, P., Stusek, M., Zeman, K., Mozny, R., Ometov, A., Hosek, J.
Number of pages: 6
Pages: 730-735
Publication date: 1 Jul 2019

Host publication information

Title of host publication: 2019 42nd International Conference on Telecommunications and Signal Processing, TSP 2019
Publisher: IEEE
Editor: Herencsar, N.
ISBN (Electronic): 9781728118642
ASJC Scopus subject areas: Signal Processing, Computer Networks and Communications, Information Systems and Management
Keywords: Data generator, Energy efficient wireless communication, Low power communication, Machine-to-Machine, Smart Grid, Wireless M-BUS

Bibliographical note

EXT="Stusek, Martin"

Source: Scopus
Source ID: 85071067560

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

On the performance of narrow-band internet of things (NB-IoT) for delay-tolerant services

Narrowband IoT (NB-IoT) stands for a radio access technology standardized by the 3GPP organization in Release 13 to enable a large set of use-cases for massive Machine-type Communications (mMTCs). Compared to legacy human-oriented 4G (LTE) communication systems, NB-IoT has game-changing features in terms of extended coverage, enhanced power saving modes, and a reduced set of available functionality. At the end of the day, these features allow for connectivity of devices in challenging positions, enabling long battery life and reducing device complexity. This article addresses the development of the universal testing device for delay-tolerant services allowing for in-depth verification of NB-IoT communication parameters. The presented outputs build upon our long-term cooperation with the Vodafone Czech Republic a.s. company.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Electrical Engineering, Brno University of Technology, Department of Telecommunication
Contributors: Mozny, R., Masek, P., Stusek, M., Zeman, K., Ometov, A., Hosek, J.
Number of pages: 6
Pages: 637-642
Publication date: 1 Jul 2019

Host publication information

Title of host publication: 2019 42nd International Conference on Telecommunications and Signal Processing, TSP 2019
Publisher: IEEE
Editor: Herencsar, N.
ISBN (Electronic): 9781728118642

Publication series

Name: 2019 42nd International Conference on Telecommunications and Signal Processing, TSP 2019
ASJC Scopus subject areas: Signal Processing, Computer Networks and Communications, Information Systems and Management
Keywords: IoT, mMTC, LPWAN, NB-IoT, Network services

Bibliographical note

EXT="Stusek, Martin"

Source: Scopus
Source ID: 85071063087

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Input magnitude data setting in error-reduction algorithm for one-dimensional discrete phase retrieval problem

In this paper we discuss how does the input magnitude data setting influence the behavior of error-reduction algorithm in the case of the one-dimensional discrete phase retrieval problem. We present experimental results related to the convergence or stagnation of the algorithm. We also discuss the issue of the zeros distribution of the solution, when the solution of the problem exists.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Computing Sciences, FETTI, Technical University of Cluj-NapocaUniversitatea Tehnica din Cluj-Napoca
Contributors: Rusu, C., Astola, J.
Publication date: 1 Jul 2019

Host publication information

Title of host publication: ISSCS 2019 - International Symposium on Signals, Circuits and Systems
Publisher: IEEE
Article number: 8801743
ISBN (Electronic): 9781728138961
ASJC Scopus subject areas: Computer Vision and Pattern Recognition, Hardware and Architecture, Signal Processing, Electrical and Electronic Engineering

Bibliographical note

EXT="Rusu, Corneliu"

Source: Scopus
Source ID: 85071848180

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

User Experience Study of 360° Music Videos on Computer Monitor and Virtual Reality Goggles

360° videos are increasingly used for media and entertainment, but the best practices for editing them are not yet well established. In this paper, we present a study in which we investigated the user experience of 360° music videos viewed on computer monitor and VR goggles. The research was conducted in the form of a laboratory experiment with 20 test participants. During the within-subject study, participants watched and evaluated four versions of the same 360° music video with a different cutting rate. Based on the results, an average cutting rate of 26 seconds delivered the highest-quality user experience both for computer monitor and VR goggles. The cutting rate matched with participants' mental models, and there was enough time to explore the environment without getting bored. Faster cutting rates made the users nervous, and a video consisting of a single shot was considered to be too static and boring.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Computing Sciences, Tampere University, Tampere University of Applied Sciences
Contributors: Holm, J., Väänänen, K., Remans, M. M. R.
Number of pages: 7
Pages: 81-87
Publication date: 1 Jul 2019

Host publication information

Title of host publication: Information Visualization - Biomedical Visualization and Geometric Modelling and Imaging, IV 2019
Publisher: IEEE
Editors: Banissi, E., Ursyn, A., McK. Bannatyne, M. W., Datia, N., Pires, J. M., Francese, R., Sarfraz, M., Wyeld, T. G., Bouali, F., Venturin, G., Azzag, H., Lebbah, M., Trutschl, M., Cvek, U., Muller, H., Nakayama, M., Kernbach, S., Caruccio, L., Risi, M., Erra, U., Vitiello, A., Rossano, V.
ISBN (Electronic): 9781728128382

Publication series

Name: Proceedings of the International Conference on Information Visualisation
ISSN (Print): 1093-9547
ASJC Scopus subject areas: Software, Signal Processing, Computer Vision and Pattern Recognition
Keywords: 360° video, cutting rate, hmd, music video, virtual reality, virtual reality goggles

Bibliographical note

jufoid=58079
EXT="Holm, Jukka"
INT=comp,"Remans, Mohammad Mushfiqur Rahman"

Source: Scopus
Source ID: 85072286445

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Low-latency Deep Clustering for Speech Separation

This paper proposes a low algorithmic latency adaptation of the deep clustering approach to speaker-independent speech separation. It consists of three parts: a) the usage of long-short-term-memory (LSTM) networks instead of their bidirectional variant used in the original work, b) using a short synthesis window (here 8 ms) required for low-latency operation, and, c) using a buffer in the beginning of audio mixture to estimate cluster centres corresponding to constituent speakers which are then utilized to separate speakers within the rest of the signal. The buffer duration would serve as an initialization phase after which the system is capable of operating with 8 ms algorithmic latency. We evaluate our proposed approach on two-speaker mixtures from Wall Street Journal (WSJ0) corpus. We observe that the use of LSTM yields around one dB lower SDR as compared to the baseline bidirectional LSTM in terms of source to distortion ratio (SDR). Moreover, using an 8 ms synthesis window instead of 32 ms degrades the separation performance by around 2.1 dB as compared to the baseline. Finally, we also report separation performance with different buffer durations noting that separation can be achieved even for buffer duration as low as 300 ms.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Computing Sciences, Research group: Audio research group - ARG
Contributors: Wang, S., Naithani, G., Virtanen, T.
Number of pages: 5
Pages: 76-80
Publication date: 1 May 2019

Host publication information

Title of host publication: 2019 IEEE International Conference on Acoustics, Speech, and Signal Processing, ICASSP 2019 - Proceedings
Publisher: IEEE
ISBN (Electronic): 9781479981311
ASJC Scopus subject areas: Software, Signal Processing, Electrical and Electronic Engineering
Keywords: Deep clustering, Low latency, Monaural speech separation

Bibliographical note

int=comp,"Wang, Shanshan"

Source: Scopus
Source ID: 85068960960

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Time Difference of Arrival Estimation of Speech Signals Using Deep Neural Networks with Integrated Time-frequency Masking

The Time Difference of Arrival (TDoA) of a sound wavefront impinging on a microphone pair carries spatial information about the source. However, captured speech typically contains dynamic non-speech interference sources and noise. Therefore, the TDoA estimates fluctuate between speech and interference. Deep Neural Networks (DNNs) have been applied for Time-Frequency (TF) masking for Acoustic Source Localization (ASL) to filter out non-speech components from a speaker location likelihood function. However, the type of TF mask for this task is not obvious. Secondly, the DNN should estimate the TDoA values, but existing solutions estimate the TF mask instead. To overcome these issues, a direct formulation of the TF masking as a part of a DNN-based ASL structure is proposed. Furthermore, the proposed network operates in an online manner, i.e., producing estimates frame-by-frame. Combined with the use of recurrent layers it exploits the sequential progression of speaker related TDoAs. Training with different microphone spacings allows model re-use for different microphone pair geometries in inference. Real-data experiments with smartphone recordings of speech in interference demonstrate the network's generalization capability.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Computing Sciences
Contributors: Pertilä, P., Parviainen, M.
Number of pages: 5
Pages: 436-440
Publication date: 1 May 2019

Host publication information

Title of host publication: 2019 IEEE International Conference on Acoustics, Speech, and Signal Processing, ICASSP 2019 - Proceedings
Publisher: IEEE
ISBN (Electronic): 9781479981311
ASJC Scopus subject areas: Software, Signal Processing, Electrical and Electronic Engineering
Keywords: Acoustic Source Localization, Microphone Arrays, Recurrent Neural Networks, Time-Frequency Masking
Electronic versions: 
Source: Scopus
Source ID: 85068957469

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Convex Energy Optimization of Streaming Applications for MPSoCs

The energy efficiency of modern MPSoCs is enhanced by complex hardware features such as Dynamic Voltage and Frequency Scaling (DVFS) and Dynamic Power Management (DPM). This paper introduces a new method, based on convex problem solving, that determines the most energy efficient operating point in terms of frequency and number of active cores in an MPSoC. The solution can challenge the popular approaches based on never-idle (or As-Slow-As-Possible (ASAP)) and race-to-idle (or As-Fast-As-Possible (AFAP)) principles. Experimental data are reported using a Samsung Exynos 5410 MPSoC and show a reduction in energy of up to 27 % when compared to ASAP and AFAP.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Computing Sciences, Universite de Rennes
Contributors: Nogues, E., Mercat, A., Arrestier, F., Pelcat, M., Menard, D.
Number of pages: 5
Pages: 1557-1561
Publication date: 1 May 2019

Host publication information

Title of host publication: 2019 IEEE International Conference on Acoustics, Speech, and Signal Processing, ICASSP 2019 - Proceedings
Publisher: IEEE
ISBN (Electronic): 9781479981311
ASJC Scopus subject areas: Software, Signal Processing, Electrical and Electronic Engineering
Source: Scopus
Source ID: 85068997223

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Deep Reinforcement Learning for Financial Trading Using Price Trailing

Developing accurate financial analysis tools can be useful both for speculative trading, as well as for analyzing the behavior of markets and promptly responding to unstable conditions ensuring the smooth operation of the financial markets. This led to the development of various methods for analyzing and forecasting the behaviour of financial assets, ranging from traditional quantitative finance to more modern machine learning approaches. However, the volatile and unstable behavior of financial markets forbids the accurate prediction of future prices, reducing the performance of these approaches. In contrast, in this paper we propose a novel price trailing method that goes beyond traditional price forecasting by reformulating trading as a control problem, effectively overcoming the aforementioned limitations. The proposed method leads to developing robust agents that can withstand large amounts of noise, while still capturing the price trends and allowing for taking profitable decisions.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Computing Sciences, Aristotle University of Thessaloniki, School of Informatics
Contributors: Zarkias, K. S., Passalis, N., Tsantekidis, A., Tefas, A.
Number of pages: 5
Pages: 3067-3071
Publication date: 1 May 2019

Host publication information

Title of host publication: 2019 IEEE International Conference on Acoustics, Speech, and Signal Processing, ICASSP 2019 - Proceedings
Publisher: IEEE
ISBN (Electronic): 9781479981311
ASJC Scopus subject areas: Software, Signal Processing, Electrical and Electronic Engineering
Keywords: Deep Reinforcement Learning, Financial Markets, Price Forecasting, Trading

Bibliographical note

EXT="Tefas, Anastasios"

Source: Scopus
Source ID: 85068989312

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

1-D Convolutional Neural Networks for Signal Processing Applications

1D Convolutional Neural Networks (CNNs) have recently become the state-of-the-art technique for crucial signal processing applications such as patient-specific ECG classification, structural health monitoring, anomaly detection in power electronics circuitry and motor-fault detection. This is an expected outcome as there are numerous advantages of using an adaptive and compact 1D CNN instead of a conventional (2D) deep counterparts. First of all, compact 1D CNNs can be efficiently trained with a limited dataset of 1D signals while the 2D deep CNNs, besides requiring 1D to 2D data transformation, usually need datasets with massive size, e.g., in the »Big Data» scale in order to prevent the well-known »overfitting» problem. 1D CNNs can directly be applied to the raw signal (e.g., current, voltage, vibration, etc.) without requiring any pre- or post-processing such as feature extraction, selection, dimension reduction, denoising, etc. Furthermore, due to the simple and compact configuration of such adaptive 1D CNNs that perform only linear 1D convolutions (scalar multiplications and additions), a real-time and low-cost hardware implementation is feasible. This paper reviews the major signal processing applications of compact 1D CNNs with a brief theoretical background. We will present their state-of-the-art performances and conclude with focusing on some major properties. Keywords - 1-D CNNs, Biomedical Signal Processing, SHM.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Computing Sciences, Research group: Multimedia Research Group - MRG, Qatar University, Electrical and Electronics Engineering Department, Izmir University of Economics
Contributors: Kiranyaz, S., Ince, T., Abdeljaber, O., Avci, O., Gabbouj, M.
Number of pages: 5
Pages: 8360-8364
Publication date: 1 May 2019

Host publication information

Title of host publication: 2019 IEEE International Conference on Acoustics, Speech, and Signal Processing, ICASSP 2019 - Proceedings
Publisher: IEEE
ISBN (Electronic): 9781479981311
ASJC Scopus subject areas: Software, Signal Processing, Electrical and Electronic Engineering

Bibliographical note

EXT="Kiranyaz, Serkan"
EXT="Ince, Turker"

Source: Scopus
Source ID: 85068995333

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Deep Temporal Logistic Bag-of-features for Forecasting High Frequency Limit Order Book Time Series

Forecasting time series has several applications in various domains. The vast amount of data that are available nowadays provide the opportunity to use powerful deep learning approaches, but at the same time pose significant challenges of high-dimensionality, velocity and variety. In this paper, a novel logistic formulation of the well-known Bag-of-Features model is proposed to tackle these challenges. The proposed method is combined with deep convolutional feature extractors and is capable of accurately modeling the temporal behavior of time series, forming powerful forecasting models that can be trained in an end-to-end fashion. The proposed method was extensively evaluated using a large-scale financial time series dataset, that consists of more than 4 million limit orders, outperforming other competitive methods.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Computing Sciences, School of Informatics, Aristotle University of Thessaloniki, Aarhus Universitet
Contributors: Passalis, N., Tefas, A., Kanniainen, J., Gabbouj, M., Iosifidis, A.
Number of pages: 5
Pages: 7545-7549
Publication date: 1 May 2019

Host publication information

Title of host publication: 2019 IEEE International Conference on Acoustics, Speech, and Signal Processing, ICASSP 2019 - Proceedings
Publisher: IEEE
ISBN (Electronic): 9781479981311
ASJC Scopus subject areas: Software, Signal Processing, Electrical and Electronic Engineering
Keywords: Limit Order Book, Temporal Bag-of-Features, Time series forecasting

Bibliographical note

EXT="Tefas, Anastasios"
EXT="Iosifidis, Alexandros"

Source: Scopus
Source ID: 85069000578

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Random Forest Oriented Fast QTBT Frame Partitioning

Block partition structure is a critical module in video coding scheme to achieve significant gap of compression performance. Under the exploration of future video coding standard by the Joint Video Exploration Team (JVET), named Versatile Video Coding (VVC), a new Quad Tree Binary Tree (QTBT) block partition structure has been introduced. In addition to the QT block partitioning defined by High Efficiency Video Coding (HEVC) standard, new horizontal and vertical BT partitions are enabled, which drastically increases the encoding time compared to HEVC. In this paper, we propose a fast QTBT partitioning scheme based on a Machine Learning approach. Complementary to techniques proposed in literature to reduce the complexity of HEVC Quad Tree (QT) partitioning, the propose solution uses Random Forest classifiers to determine for each block which partition modes between QT and BT is more likely to be selected. Using uncertainty zones of classifier decisions, the proposed complexity reduction technique is able to reduce in average by 30% the encoding time of JEM-v7.0 software in Random Access configuration with only 0.57% Bjontegaard Delta Rate (BD-BR) increase.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Computing Sciences, Universite de Rennes, MMP
Contributors: Amestoy, T., Mercat, A., Hamidouche, W., Bergeron, C., Menard, D.
Number of pages: 5
Pages: 1837-1841
Publication date: 1 May 2019

Host publication information

Title of host publication: 2019 IEEE International Conference on Acoustics, Speech, and Signal Processing, ICASSP 2019 - Proceedings
Publisher: IEEE
ISBN (Electronic): 9781479981311
ASJC Scopus subject areas: Software, Signal Processing, Electrical and Electronic Engineering
Keywords: Complexity Reduction, JEM, Machine Learning, QTBT, Random Forest, Video Compression, VVC
Source: Scopus
Source ID: 85068966990

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Open framework for mammography-based breast cancer risk assessment

In recent years, several studies have established a relationship between mammographic parenchymal patterns and breast cancer risk. However, there is a lack of publicly available data and software for objective comparison and clinical validation. This paper presents an open and adaptable implementation (OpenBreast v1.0) of a fully-Automatic computerized framework for mammographic image analysis for breast cancer risk assessment. OpenBreast implements mammographic image analysis in four stages: breast segmentation, detection of region-of-interests, feature extraction and risk scoring. For each stage, we provide implementations of several state-of-The-Art methods. The pipeline is tested on a set of 305 full-field digital mammography images corresponding to 84 patients (51 cases and 49 controls) from the breast cancer digital repository (BCDR). OpenBreast achieves a competitive AUC of 0.846 in breast cancer risk assessment. In addition, used jointly with widely accepted risk factors such as patient age and breast density, mammographic image analysis using OpenBreast shows a statistically significant improvement in performance with an AUC of 0.876 (\mathrm{p}<0.001). Our framework will be made publicly available and it is easy to incorporate new methods.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Computing Sciences, Research group: Vision, Universidad Industrial de Santander, Tampere University, Brigham and Women's Hospital
Contributors: Pertuz, S., Torres, G. F., Tamimi, R., Kämäräinen, J.
Publication date: 1 May 2019

Host publication information

Title of host publication: 2019 IEEE EMBS International Conference on Biomedical and Health Informatics, BHI 2019 - Proceedings
Publisher: IEEE
ISBN (Electronic): 9781728108483
ASJC Scopus subject areas: Artificial Intelligence, Signal Processing, Information Systems and Management, Biomedical Engineering, Health Informatics, Radiology Nuclear Medicine and imaging
Keywords: Breast cancer, Mammography, Parenchymal analysis, Risk assessment, Texture analysis

Bibliographical note

EXT="Pertuz, Said"

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Variance Preserving Initialization for Training Deep Neuromorphic Photonic Networks with Sinusoidal Activations

Photonic neuromorphic hardware can provide significant performance benefits for Deep Learning (DL) applications by accelerating and reducing the energy requirements of DL models. However, photonic neuromorphic architectures employ different activation elements than those traditionally used in DL, slowing down the convergence of the training process for such architectures. An initialization scheme that can be used to efficiently train deep photonic networks that employ quadratic sinusoidal activation functions is proposed in this paper. The proposed initialization scheme can overcome these limitations, leading to faster and more stable training of deep photonic neural networks. The ability of the proposed method to improve the convergence of the training process is experimentally demonstrated using two different DL architectures and two datasets.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Computing Sciences, Aristotle University of Thessaloniki
Contributors: Passalis, N., Mourgias-Alexandris, G., Tsakyridis, A., Pleros, N., Tefas, A.
Number of pages: 5
Pages: 1483-1487
Publication date: 1 May 2019

Host publication information

Title of host publication: 2019 IEEE International Conference on Acoustics, Speech, and Signal Processing, ICASSP 2019 - Proceedings
Publisher: IEEE
ISBN (Electronic): 9781479981311
ASJC Scopus subject areas: Software, Signal Processing, Electrical and Electronic Engineering
Keywords: Neuromorphic Hardware, Photonic Neural Networks, Sinusoidal Activations

Bibliographical note

EXT="Tefas, Anastasios"

Source: Scopus
Source ID: 85064389224

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Automatic detection of water inside concrete slabs using ground penetrating radar

Ground Penetrating Radar (GPR) is generally used as a non-destructive method of inspection for structures and for finding defects in concrete slabs. In this paper, GPR is used in the detection of water inside the cavities of concrete hollow core slabs. We propose an algorithm that determines the water level inside the concrete slab by analyzing the time delays of the reflections originating from inside the cavity. The algorithm is based on utilizing prior knowledge about the geometry of the hollow core slab. The presence of water was successfully detected and an estimate for the height of the water surface was obtained with a GPR system operating with a central frequency of 2.7 GHz. Based on the experiments, the proposed method holds promise in providing a robust and accurate method for the detection of water inside the concrete slabs. Results, possible future research and analysis of the feasibility of GPR systems in water detection are presented and discussed.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Computing Sciences, Research group: MMDM
Contributors: Khan, M. A., Vehmas, R., Visa, A.
Publication date: 1 Apr 2019

Host publication information

Title of host publication: 2019 IEEE Radar Conference, RadarConf 2019
Publisher: IEEE
ISBN (Electronic): 9781728116792
ASJC Scopus subject areas: Computer Networks and Communications, Signal Processing, Instrumentation

Bibliographical note

jufoid=57477

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Exploiting Multipath Terahertz Communications for Physical Layer Security in beyond 5G Networks

Terahertz (THz) band communications, capable of achieving the theoretical capacity of up to several terabits-per-second, are one of the attractive enablers for beyond 5G wireless networks. THz systems will use extremely directional narrow beams, allowing not only to extend the communication range but also to partially secure the data already at the physical layer. The reason is that, in most cases, the Attacker has to be located within the transmitter beam in order to eavesdrop the message. However, even the use of very narrow beams results in the considerably large area around the receiver, where the Attacker can capture all the data. In this paper, we study how to decrease the message eavesdropping probability by leveraging the inherent multi-path nature of the THz communications. We particularly propose sharing the data transmission over multiple THz propagation paths currently available between the communicating entities. We show that, at a cost of the slightly reduced link capacity, the message eavesdropping probability in the described scheme decreases significantly even when several Attackers operate in a cooperative manner. The proposed solution can be utilized for the transmission of the sensitive data, as well as to secure the key exchange in THz band networks beyond 5G.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Electrical Engineering, Research group: Wireless Communications and Positioning, State University of New York
Contributors: Petrov, V., Moltchanov, D., Jornet, J. M., Koucheryavy, Y.
Number of pages: 8
Pages: 865-872
Publication date: 1 Apr 2019

Host publication information

Title of host publication: INFOCOM 2019 - IEEE Conference on Computer Communications Workshops, INFOCOM WKSHPS 2019
Publisher: IEEE
ISBN (Electronic): 9781728118789
ASJC Scopus subject areas: Hardware and Architecture, Signal Processing, Information Systems and Management, Safety, Risk, Reliability and Quality, Computer Networks and Communications

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Improved Session Continuity in 5G NR with Joint Use of Multi-Connectivity and Guard Bandwidth

The intermittent millimeter-wave radio links as a result of human-body blockage are an inherent feature of the 5G New Radio (NR) technology by 3GPP. To improve session continuity in these emerging systems, two mechanisms have recently been proposed, namely, multi-connectivity and guard bandwidth. The former allows to establish multiple spatially-diverse connections and switch between them dynamically, while the latter reserves a fraction of system bandwidth for sessions changing their state from non-blocked to blocked, which ensures that the ongoing sessions have priority over the new ones. In this paper, we assess the joint performance of these two schemes for the user- and system-centric metrics of interest. Our numerical results reveal that the multi-connectivity operation alone may not suffice to increase the ongoing session drop probability considerably. On the other hand, the use of guard bandwidth significantly improves session continuity by somewhat compromising new session drop probability and system resource utilization. Surprisingly, the 5G NR system implementing both these techniques inherits their drawbacks. However, complementing it with an initial AP selection procedure effectively alleviates these limitations by maximizing the system resource utilization, while still providing sufficient flexibility to enable the desired trade-off between new and ongoing session drop probabilities.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Electrical Engineering, Department of Chemistry and Bioengineering, Peoples’ Friendship University of Russia
Contributors: Kovalchukov, R., Moltchanov, D., Begishev, V., Samuylov, A., Andreev, S., Koucheryavy, Y., Samouylov, K.
Publication date: 20 Feb 2019

Host publication information

Title of host publication: 2018 IEEE Global Communications Conference, GLOBECOM 2018
Publisher: IEEE
ISBN (Electronic): 9781538647271
ASJC Scopus subject areas: Information Systems and Management, Renewable Energy, Sustainability and the Environment, Safety, Risk, Reliability and Quality, Signal Processing, Modelling and Simulation, Instrumentation, Computer Networks and Communications
Source: Scopus
Source ID: 85063532495

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Energy Detection-Based Spectrum Sensing over Fisher-Snedecor F Fading Channels

This paper investigates the performance of energy detection-based spectrum sensing over Fisher-Snedecor F fading channels. To this end, an analytical expression for the corre- sponding average detection probability is firstly derived and then this is extended to account for collaborative spectrum sensing. The complementary receiver operating characteristics (ROC) are analyzed for different conditions of the average signal-to- noise ratio (SNR), time-bandwidth product, multipath fading, shadowing and number of collaborating users. It is shown that the energy detection performance is strongly linked to the severity of the multipath fading and amount of shadowing, whereby even small variations in either of these physical phenomena significantly impact the detection probability. Also, the versatile modeling capability of the Fisher-Snedecor F distribution is veridfied in the context of energy detection based spectrum sensing as it provides considerably more accurate characterization than the conventional Rayleigh fading model. To confirm the validity of the analytical results presented in this paper, we compare them with the results of some simulations.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Research group: Wireless Communications and Positioning, Electrical Engineering, Queen's University, Belfast, Northern Ireland, Centre for Wireless Innovation, Khalifa University, Department of Chemistry and Bioengineering, University of Surrey, German Jordanian University, Aristotle University of Thessaloniki
Contributors: Yoo, S. K., Cotton, S. L., Sofotasios, P. C., Muhaidat, S., Badarneh, O. S., Karagiannidis, G. K.
Publication date: 20 Feb 2019

Host publication information

Title of host publication: 2018 IEEE Global Communications Conference
Publisher: IEEE
Article number: 8647778
ISBN (Electronic): 9781538647271
ASJC Scopus subject areas: Information Systems and Management, Renewable Energy, Sustainability and the Environment, Safety, Risk, Reliability and Quality, Signal Processing, Modelling and Simulation, Instrumentation, Computer Networks and Communications
Source: Scopus
Source ID: 85063500863

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

The Direction Cosine Matrix Algorithm in Fixed-point: Implementation and Analysis

Inertial navigation allows tracking and updating the position and orientation of a moving object based on accelerometer and gyroscope data without external positioning aid, such as GPS. Therefore, inertial navigation is an essential technique for, e.g., indoor positioning. As inertial navigation is based on integration of acceleration vector components, computation errors accumulate and make the position and orientation estimate drift. Even though maximum computation precision is desired, also efficiency needs consideration in the age of Internet-of-Things, to enable deployment of inertial navigation based applications to the smallest devices. This work formulates the Direction Cosine Matrix update algorithm, a central component for inertial navigation, in fixed-point and analyzes its precision and computation load compared to a regular floating-point implementation. The results show that the fixed-point version maintains very high precision, while requiring no floating point hardware for operation. The paper presents execution time results on three very different embedded processors.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Computing Sciences
Contributors: Meirhaeghe, A., Boutellier, J., Collin, J.
Publication date: 2019

Host publication information

Title of host publication: ICASSP 2019 - 2019 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP)
Publisher: IEEE
ISBN (Print): 978-1-4799-8132-8
ISBN (Electronic): 978-1-4799-8131-1
ASJC Scopus subject areas: Signal Processing

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Efficient Solving of Markov Decision Processes on GPUs Using Parallelized Sparse Matrices

Markov Decision Processes (MDPs) provide important capabilities for facilitating the dynamic adaptation of hardware and software configurations to the environments in which they operate. However, the use of MDPs in embedded signal processing systems is limited because of the large computational demands for solving this class of system models. This paper presents Sparse Parallel Value Iteration (SPVI), a new algorithm for solving large MDPs on resource-constrained embedded systems that are equipped with mobile GPUs. SPVI leverages recent advances in parallel solving of MDPs and adds sparse linear algebra techniques to significantly outperform the state-of-the-art. The method and its application are described in detail, and demonstrated with case studies that are implemented on an NVIDIA Tegra K1 System On Chip (SoC). The experimental results show execution time improvements in the range of 65 % -78% for several applications. SPVI also lifts restrictions required by other MDP solver approaches, making it more widely compatible with large classes of optimization problems.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Research area: Computer engineering, Computing Sciences, University of Maryland, Department of Electrical and Computer Engineering, Georgia Institute of Technology
Contributors: Sapio, A., Bhattacharyya, S. S., Wolf, M.
Number of pages: 6
Pages: 13-18
Publication date: Dec 2018

Host publication information

Title of host publication: 2018 Conference on Design and Architectures for Signal and Image Processing, DASIP 2018
Publisher: IEEE COMPUTER SOCIETY PRESS
ISBN (Electronic): 9781538682371

Publication series

Name: Conference on Design and Architectures for Signal and Image Processing, DASIP
ISSN (Print): 2164-9766
ASJC Scopus subject areas: Computer Graphics and Computer-Aided Design, Computer Vision and Pattern Recognition, Hardware and Architecture, Signal Processing, Electrical and Electronic Engineering
Keywords: CUDA, GPU, Markov decision processes, MDP, Sparsity, Value iteration

Bibliographical note

jufoid=71852

Source: Scopus
Source ID: 85061388518

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

An active learning method using clustering and committee-based sample selection for sound event classification

This paper proposes an active learning method to control a labeling process for efficient annotation of acoustic training material, which is used for training sound event classifiers. The proposed method performs K-medoids clustering over an initially unlabeled dataset, and medoids as local representatives, are presented to an annotator for manual annotation. The annotated label on a medoid propagates to other samples in its cluster for label prediction. After annotating the medoids, the annotation continues to the unexamined sounds with mismatched prediction results from two classifiers, a nearest-neighbor classifier and a model-based classifier, both trained with annotated data. The annotation on the segments with mismatched predictions are ordered by the distance to the nearest annotated sample, farthest first. The evaluation is made on a public environmental sound dataset. The labels obtained through a labeling process controlled by the proposed method are used to train a classifier, using supervised learning. Only 20% of the data needs to be manually annotated with the proposed method, to achieve the accuracy with all the data annotated. In addition, the proposed method clearly outperforms other active learning algorithms proposed for sound event classification through all the experiments, simulating varying fraction of data that is manually labeled.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Signal Processing, Research group: Audio research group - ARG
Contributors: Shuyang, Z., Heittola, T., Virtanen, T.
Number of pages: 5
Pages: 116-120
Publication date: 2 Nov 2018

Host publication information

Title of host publication: 16th International Workshop on Acoustic Signal Enhancement, IWAENC 2018
Publisher: IEEE
ISBN (Electronic): 9781538681510
ASJC Scopus subject areas: Signal Processing, Acoustics and Ultrasonics
Keywords: Active learning, Committee-based sample selection, K-medoids clustering, Sound event classification
Electronic versions: 
Source: Scopus
Source ID: 85057424847

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Using sequential information in polyphonic sound event detection

To detect the class, and start and end times of sound events in real world recordings is a challenging task. Current computer systems often show relatively high frame-wise accuracy but low event-wise accuracy. In this paper, we attempted to merge the gap by explicitly including sequential information to improve the performance of a state-of-the-art polyphonic sound event detection system. We propose to 1) use delayed predictions of event activities as additional input features that are fed back to the neural network; 2) build N-grams to model the co-occurrence probabilities of different events; 3) use se-quentialloss to train neural networks. Our experiments on a corpus of real world recordings show that the N-grams could smooth the spiky output of a state-of-the-art neural network system, and improve both the frame-wise and the event-wise metrics.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Signal Processing, Research group: Audio research group - ARG
Contributors: Huang, G., Heittola, T., Virtanen, T.
Number of pages: 5
Pages: 291-295
Publication date: 2 Nov 2018

Host publication information

Title of host publication: 16th International Workshop on Acoustic Signal Enhancement, IWAENC 2018
Publisher: IEEE
ISBN (Electronic): 9781538681510
ASJC Scopus subject areas: Signal Processing, Acoustics and Ultrasonics
Keywords: Language modelling, Polyphonic sound event detection, Sequential information
Source: Scopus
Source ID: 85057368244

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Acoustic scene classification: An overview of dcase 2017 challenge entries

We present an overview of the challenge entries for the Acoustic Scene Classification task of DCASE 2017 Challenge. Being the most popular task of the challenge, acoustic scene classification entries provide a wide variety of approaches for comparison, with a wide performance gap from top to bottom. Analysis of the submissions confirms once more the popularity of deep-learning approaches and mel frequency representations. Statistical analysis indicates that the top ranked system performed significantly better than the others, and that combinations of top systems are capable of reaching close to perfect performance on the given data.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Signal Processing, Research group: Audio research group - ARG
Contributors: Mesaros, A., Heittola, T., Virtanen, T.
Number of pages: 5
Pages: 411-415
Publication date: 2 Nov 2018

Host publication information

Title of host publication: 16th International Workshop on Acoustic Signal Enhancement, IWAENC 2018
Publisher: IEEE
ISBN (Electronic): 9781538681510
ASJC Scopus subject areas: Signal Processing, Acoustics and Ultrasonics
Keywords: Acoustic scene classification, Audio classb ification, DCASE challenge
Source: Scopus
Source ID: 85057432865

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Time-frequency masking strategies for single-channel low-latency speech enhancement using neural networks

This paper presents a low-latency neural network based speech enhancement system. Low-latency operation is critical for speech communication applications. The system uses the time-frequency (TF) masking approach to retain speech and remove the non-speech content from the observed signal. The ideal TF mask are obtained by supervised training of neural networks. As the main contribution different neural network models are experimentally compared to investigate computational complexity and speech enhancement performance. The proposed system is trained and tested on noisy speech data where signal-to-noise ratio (SNR) ranges from -5 dB to +5 dB and the results show significant reduction of non-speech content in the resulting signal while still meeting a low-latency operation criterion, which is here considered to be less than 20 ms.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Signal Processing, Research group: Audio research group - ARG, Huawei European Research Center
Contributors: Parviainen, M., Pertila, P., Virtanen, T., Grosche, P.
Number of pages: 5
Pages: 51-55
Publication date: 2 Nov 2018

Host publication information

Title of host publication: 16th International Workshop on Acoustic Signal Enhancement, IWAENC 2018
Publisher: IEEE
ISBN (Electronic): 9781538681510
ASJC Scopus subject areas: Signal Processing, Acoustics and Ultrasonics
Keywords: Neural networks, Speech enhancement
Electronic versions: 
Source: Scopus
Source ID: 85057354159

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Deep neural network based speech separation optimizing an objective estimator of intelligibility for low latency applications

Mean square error (MSE) has been the preferred choice as loss function in the current deep neural network (DNN) based speech separation techniques. In this paper, we propose a new cost function with the aim of optimizing the extended short time objective intelligibility (ESTOI) measure. We focus on applications where low algorithmic latency (≤ 10 ms) is important. We use long short-term memory networks (LSTM) and evaluate our proposed approach on four sets of two-speaker mixtures from extended Danish hearing in noise (HINT) dataset. We show that the proposed loss function can offer improved or at par objective intelligibility (in terms of ESTOI) compared to an MSE optimized baseline while resulting in lower objective separation performance (in terms of the source to distortion ratio (SDR)). We then proceed to propose an approach where the network is first initialized with weights optimized for MSE criterion and then trained with the proposed ESTOI loss criterion. This approach mitigates some of the losses in objective separation performance while preserving the gains in objective intelligibility.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Signal Processing, Research group: Audio research group - ARG, Oticon A/S
Contributors: Naithani, G., Nikunen, J., Bramslow, L., Virtanen, T.
Number of pages: 5
Pages: 386-390
Publication date: 2 Nov 2018

Host publication information

Title of host publication: 16th International Workshop on Acoustic Signal Enhancement, IWAENC 2018
Publisher: IEEE
ISBN (Electronic): 9781538681510
ASJC Scopus subject areas: Signal Processing, Acoustics and Ultrasonics
Keywords: Deep neural networks, Low latency, Speech intelligibility, Speech separation
Source: Scopus
Source ID: 85057383332

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Multichannel NMF for source separation with ambisonic signals

This paper proposes a novel method for separation of sound sources with ambisonic signals using multichannel non-negative matrix factorization (MNMF) for source spectrogram estimation. We present a novel frequency-independent spatial covariance matrix (SCM) model for spherical harmonic (SH) domain signals which makes the MNMF parameter estimation framework computationally feasible up to 3rd order SH signals. The evaluation is done with simulated SH domain mixtures by measuring the separation performance using objective criteria and comparing the proposed method against SH domain beamforming. The proposed method improves average separation performance over beamforming with post-filtering when using 1st and 2nd order SH signals while at higher orders performance among all tested methods is similar.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Signal Processing, Aalto University
Contributors: Nikunen, J., Politis, A.
Number of pages: 5
Pages: 251-255
Publication date: 2 Nov 2018

Host publication information

Title of host publication: 16th International Workshop on Acoustic Signal Enhancement, IWAENC 2018
Publisher: IEEE
ISBN (Electronic): 9781538681510
ASJC Scopus subject areas: Signal Processing, Acoustics and Ultrasonics
Keywords: Ambisonics, Multichannel NMF, Source separation
Source: Scopus
Source ID: 85057417393

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Identification of Parkinson's Disease Utilizing a Single Self-recorded 20-step Walking Test Acquired by Smartphone's Inertial Measurement Unit

Parkinson's disease (PD) is a degenerative and long-term disorder of the central nervous system, which often causes motor symptoms, e.g., tremor, rigidity, and slowness. Currently, the diagnosis of PD is based on patient history and clinical examination. Technology-derived decision support systems utilizing, for example, sensor-rich smartphones can facilitate more accurate PD diagnosis. These technologies could provide less obtrusive and more comfortable remote symptom monitoring. The recent studies showed that motor symptoms of PD can reliably be detected from data gathered via smartphones. The current study utilized an open-access dataset named 'mPower' to assess the feasibility of discriminating PD from non-PD by analyzing a single self-administered 20-step walking test. From this dataset, 1237 subjects (616 had PD) who were age and gender matched were selected and classified into PD and non-PD categories. Linear acceleration (ACC) and gyroscope (GYRO) were recorded by built-in sensors of smartphones. Walking bouts were extracted by thresholding signal magnitude area of the ACC signals. Features were computed from both ACC and GYRO signals and fed into a random forest classifier of size 128 trees. The classifier was evaluated deploying 100-fold cross-validation and provided an accumulated accuracy rate of 0.7 after 10k validations. The results show that PD and non-PD patients can be separated based on a single short-lasting self-administered walking test gathered by smartphones' built-in inertial measurement units.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Faculty of Biomedical Sciences and Engineering, Research group: Personal Health Informatics-PHI, Unit of Neurology, Satakunta Central Hospital
Contributors: Mehrang, S., Jauhiainen, M., Pietilä, J., Puustinen, J., Ruokolainen, J., Nieminen, H.
Number of pages: 4
Pages: 2913-2916
Publication date: 26 Oct 2018

Host publication information

Title of host publication: 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBC 2018
Volume: 2018-July
Publisher: Institute of Electrical and Electronics Engineers Inc.
Article number: 8512921
ISBN (Electronic): 9781538636466
ASJC Scopus subject areas: Signal Processing, Biomedical Engineering, Computer Vision and Pattern Recognition, Health Informatics
Source: Scopus
Source ID: 85056600537

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Eigen Posture Based Fall Risk Assessment System Using Kinect

Postural Instability (PI) is a major reason for fall in geriatric population as well as for people with diseases or disorders like Parkinson's, stroke etc. Conventional stability indicators like Berg Balance Scale (BBS) require clinical settings with skilled personnel's interventions to detect PI and finally classify the person into low, mid or high fall risk categories. Moreover these tests demand a number of functional tasks to be performed by the patient for proper assessment. In this paper a machine learning based approach is developed to determine fall risk with minimal human intervention using only Single Limb Stance exercise. The analysis is done based on the spatiotemporal dynamics of skeleton joint positions obtained from Kinect sensor. A novel posture modeling method has been applied for feature extraction along with some traditional time domain and metadata features to successfully predict the fall risk category. The proposed unobstrusive, affordable system is tested over 224 subjects and is able to achieve 75% mean accuracy on the geriatric and patient population.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Signal Processing, Tata Consultancy Services India
Contributors: Tripathy, S. R., Chakravarty, K., Sinha, A.
Number of pages: 4
Pages: 1-4
Publication date: 26 Oct 2018

Host publication information

Title of host publication: 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBC 2018
Volume: 2018-July
Publisher: IEEE
Article number: 8513263
ISBN (Electronic): 9781538636466
ASJC Scopus subject areas: Signal Processing, Biomedical Engineering, Computer Vision and Pattern Recognition, Health Informatics
Keywords: BBS, Eigenpose, EMD, Fall risk, Index Terms-Kinect
Source: Scopus
Source ID: 85056666030

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

The Accuracy of Atrial Fibrillation Detection from Wrist Photoplethysmography. A Study on Post-Operative Patients

Atrial fibrillation (AF) is the most common type of cardiac arrhythmia. Although not life-threatening itself, AF significantly increases the risk of stroke and myocardial infarction. Current tools available for screening and monitoring of AF are inadequate and an unobtrusive alternative, suitable for long-term use, is needed. This paper evaluates an atrial fibrillation detection algorithm based on wrist photoplethysmographic (PPG) signals. 29 patients recovering from surgery in the post-anesthesia care unit were monitored. 15 patients had sinus rhythm (SR, 67.5± 10.7 years old, 7 female) and 14 patients had AF (74.8± 8.3 years old, 8 female) during the recordings. Inter-beat intervals (IBI) were estimated from PPG signals. As IBI estimation is highly sensitive to motion or other types of noise, acceleration signals and PPG waveforms were used to automatically detect and discard unreliable IBI. AF was detected from windows of 20 consecutive IBI with 98.45±6.89% sensitivity and 99.13±1.79% specificity for 76.34±19.54% of the time. For the remaining time, no decision was taken due to the lack of reliable IBI. The results show that wrist PPG is suitable for long term monitoring and AF screening. In addition, this technique provides a more comfortable alternative to ECG devices.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Faculty of Biomedical Sciences and Engineering, Research group: Sensor Technology and Biomeasurements (STB), PulseOn SA, Tampere University Hospital
Contributors: Tarniceriu, A., Harju, J., Yousefi, Z. R., Vehkaoja, A., Parak, J., Yli-Hankala, A., Korhonen, I.
Number of pages: 4
Pages: 4844-4847
Publication date: 26 Oct 2018

Host publication information

Title of host publication: 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBC 2018
Volume: 2018-July
Publisher: IEEE
Article number: 8513197
ISBN (Electronic): 9781538636466
ASJC Scopus subject areas: Signal Processing, Biomedical Engineering, Computer Vision and Pattern Recognition, Health Informatics

Bibliographical note

INT=tut-bmt, "Yousefi, Zeinab Rezaei"

Source: Scopus
Source ID: 85056672654

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

LoTTA: Energy-Efficient Processor for Always-on Applications

Various use cases in the era of Internet-of-Things (IoT) demand processor devices to have low energy consumption in order to maximize the battery life. In addition to energy constraints, there is often a need to both swiftly execute control-oriented code to provide low reaction times and to occasionally perform real time signal processing tasks efficiently. As a response to these requirements, we propose LoTTA, an extremely energy-efficient exposed datapath core. Its transport-triggered programming model helps in lowering the execution latency via low cost data forwarding. Control efficiency is achieved by an optimized control unit with zero delay slot branches and predicated execution. An instruction register file is included for frequently executed program hot spots to reduce the instruction stream energy consumption. These features allow the processor to execute CHStone and EEMBC CoreMark benchmarks on average with 19% fewer cycles compared to a 6-stage LM32, a traditional RISC core with similar datapath resources. The core consumes 53% less energy on average compared to the RISC core. When including the instruction stream overheads, in the best case, LoTTA saves 79% energy, and on average 40%.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Pervasive Computing, Research area: Computer engineering
Contributors: Multanen, J., Kultala, H., Jääskeläinen, P., Viitanen, T., Tervo, A., Takala, J.
Publication date: Oct 2018

Host publication information

Title of host publication: 2018 IEEE International Workshop on Signal Processing Systems (SiPS)
Publisher: IEEE
ISBN (Print): 978-1-5386-6319-6
ISBN (Electronic): 978-1-5386-6318-9
ASJC Scopus subject areas: Computer Science(all), Hardware and Architecture, Signal Processing
Keywords: Energy efficiency, low power, Computer architecture, IoT, always-on, Processor

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Estimation of time-varying room impulse responses of multiple sound sources from observed mixture and isolated source signals

This paper proposes a method for online estimation of time-varying room impulse responses (RIR) between multiple isolated sound sources and a far-field mixture. The algorithm is formulated as adaptive convolutive filtering in short-time Fourier transform (STFT) domain. We use the recursive least squares (RLS) algorithm for estimating the filter parameters due to its fast convergence rate, which is required for modeling rapidly changing RIRs of moving sound sources. The proposed method allows separation of reverberated sources from the far-field mixture given that their close-field signals are available. The evaluation is based on measuring unmixing performance (removal of reverberated source) using objective separation criteria calculated between the ground truth recording of the preserved sources and the unmixing result obtained with the proposed algorithm. We compare online and offline formulations for the RIR estimation and also provide evaluation with blind source separation algorithm only operating on the mixture signal.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Signal Processing, Research group: Audio research group - ARG
Contributors: Nikunen, J., Virtanen, T.
Number of pages: 5
Pages: 421-425
Publication date: 10 Sep 2018

Host publication information

Title of host publication: 2018 IEEE International Conference on Acoustics, Speech, and Signal Processing, ICASSP 2018 - Proceedings
Volume: 2018-April
Publisher: Institute of Electrical and Electronics Engineers Inc.
Article number: 8462535
ISBN (Print): 9781538646588

Publication series

Name:  Proceedings of the IEEE International Conference on Acoustics, Speech, and Signal Processing
ISSN (Electronic): 2379-190X
ASJC Scopus subject areas: Software, Signal Processing, Electrical and Electronic Engineering
Keywords: Adaptive filtering, Informed source separation, Online room impulse response estimation, Source unmixing

Bibliographical note

jufoid=57409

Source: Scopus
Source ID: 85054234348

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Low-energy graph fourier basis functions span salient objects

There is an emerging interest aiming at defining principles for signals on general graphs, which are analogous to the basic principles in traditional signal processing. One example is the Graph Fourier Transform which aims at decomposing a graph signal into its components based on a set of basis functions with corresponding graph frequencies. It has been observed that most of the important information of a graph signal is contained inside the low frequency band, which leads to several applications such as denoising, compression, etc. In this paper, we show that the low frequency basis functions span the salient regions in an image, which can also be considered as important regions. Motivated by this, we present a novel simple and unsupervised method to utilize a number of low-energy basis functions and show that it improves the performance of seven state-of-the-art salient object detection methods in five datasets under four different evaluation criteria, with only minor exceptions.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Signal Processing, Research group: Multimedia Research Group - MRG
Contributors: Malik, J., Aytekin, C., Gabbouj, M.
Number of pages: 5
Pages: 1548-1552
Publication date: 10 Sep 2018

Host publication information

Title of host publication: 2018 IEEE International Conference on Acoustics, Speech, and Signal Processing, ICASSP 2018 - Proceedings
Volume: 2018-April
Publisher: Institute of Electrical and Electronics Engineers Inc.
Article number: 8462672
ISBN (Print): 9781538646588
ASJC Scopus subject areas: Software, Signal Processing, Electrical and Electronic Engineering
Keywords: Graph fourier transform, Graph signal processing, Salient object detection

Bibliographical note

jufoid=57409

Source: Scopus
Source ID: 85054244934

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Statistical Evaluation of Visual Quality Metrics for Image Denoising

This paper studies the problem of full reference visual quality assessment of denoised images with a special emphasis on images with low contrast and noise-like texture. Denoising of such images together with noise removal often results in image details loss or smoothing. A new test image database, FLT, containing 75 noise-free 'reference' images and 300 filtered ('distorted') images is developed. Each reference image, corrupted by an additive white Gaussian noise, is denoised by the BM3D filter with four different values of threshold parameter (four levels of noise suppression). After carrying out a perceptual quality assessment of distorted images, the mean opinion scores (MOS) are obtained and compared with the values of known full reference quality metrics. As a result, the Spearman Rank Order Correlation Coefficient (SROCC) between PSNR values and MOS has a value close to zero, and SROCC between values of known full-reference image visual quality metrics and MOS does not exceed 0.82 (which is reached by a new visual quality metric proposed in this paper). The FLT dataset is more complex than earlier datasets used for assessment of visual quality for image denoising. Thus, it can be effectively used to design new image visual quality metrics for image denoising.

General information

Publication status: Published
MoE publication type: A4 Article in a conference publication
Organisations: Signal Processing, Research group: Computational Imaging-CI, National Aerospace University
Contributors: Egiazarian, K., Ponomarenko, M., Lukin, V., Ieremeiev, O.
Number of pages: 5
Pages: 6752-6756
Publication date: 10 Sep 2018

Host publication information

Title of host publication: 2018 IEEE International Conference on Acoustics, Speech, and Signal Processing, ICASSP 2018 - Proceedings
Volume: 2018-April
Publisher: Institute of Electrical and Electronics Engineers Inc.
Article number: 8462294
ISBN (Print): 9781538646588
ASJC Scopus subject areas: Software, Signal Processing, Electrical and Electronic Engineering
Keywords: BM3D, Full-reference metrics, Image denoising, Image visual quality assessment

Bibliographical note

EXT="Lukin, Vladimir"
JUFOID=57409

Source: Scopus
Source ID: 85054084165

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

A joint target localization and classification framework for sensor networks

In this paper, we propose a joint framework for target localization and classification using a single generalized model for non-imaging based multi-modal sensor data. For target localizat