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FFT-domain signal processing for spectrally-enhanced CP-OFDM waveforms in 5G new radio

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

Details

Original languageEnglish
Title of host publication2018 52nd Asilomar Conference on Signals, Systems, and Computers
PublisherIEEE
Pages1049-1056
ISBN (Electronic)978-1-5386-9218-9
ISBN (Print)978-1-5386-9219-6
DOIs
Publication statusPublished - Oct 2018
Publication typeA4 Article in a conference publication
EventAsilomar Conference on Signals, Systems and Computers -
Duration: 1 Jan 1900 → …

Publication series

Name
ISSN (Print)1058-6393

Conference

ConferenceAsilomar Conference on Signals, Systems and Computers
Period1/01/00 → …

Abstract

Fast Fourier transform (FFT)-domain signal processing has been considered recently as an effective tool for spectrum enhancement of orthogonal frequency-division multiplexing (OFDM)-based waveforms, which is a central element in the fifth generation new radio (5G-NR) developments. Fast-convolution (FC) filtering approximates linear convolution by effective FFT-based block-wise circular convolutions using partly overlapping processing blocks. In earlier work, we have shown that FC processing is a very flexible and efficient tool for filtered OFDM signal generation and receiver-side subband filtering, e.g., for the mixed numerology scenarios of the 5G-NR. However, with the continuous overlap-save and overlap-add processing models with fixed block-size and overlap, the FC-processing blocks are not synchronized to all OFDM symbols of a transmission frame. Furthermore, 5G-NR numerology does not allow to use transform lengths smaller than 128 because this would lead to non-integer cyclic prefix (CP) lengths. Here we present a modified FC processing scheme which avoids these limitations. The scheme is based on extrapolating the CP samples which, as an example, makes it possible to use 16-point transforms in case of a 12-subcarrier-wide subband allocation, greatly reducing the implementation complexity. Also the FC-processing blocks can be aligned with each OFDM symbol, reducing complexity and latency, e.g., in mini-slot transmissions.

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