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Performance Analysis of Non-Orthogonal Multiple Access under I/Q Imbalance

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Details

Original languageEnglish
Pages (from-to)18453 - 18468
JournalIEEE Access
Volume6
Early online date28 Mar 2018
DOIs
Publication statusPublished - 2018
Publication typeA1 Journal article-refereed

Abstract

Non-orthogonal multiple access (NOMA) has been recently proposed as a viable technology that can potentially improve the spectral efficiency of fifth generation (5G) wireless networks and beyond. However, in practical communication scenarios, transceiver architectures inevitably suffer from radio-frequency (RF) front-end related impairments that can lead to degradation of the overall system performance with in-phase/quadrature-phase imbalance (IQI) constituting a major impairment in direct-conversion transceivers. In this article, we quantify the effects of IQI on the performance of NOMA based single-carrier (SC) and multi-carrier (MC) systems under multipath fading conditions. This is realized by first deriving analytic expressions for the signal-to-interference-plus-noise ratio and the outage probability of both SC and MC NOMA systems subject to IQI at the transmitter and/or receiver (RX) side. Furthermore, we derive asymptotic diversity orders for all considered impairment scenarios. Capitalizing on these results, we demonstrate that the effects of IQI differ considerably among NOMA users and depend on the underlying systems’ parameters. For example, for a target data rate and power allocation ratio satisfying a given condition, IQI does not affect the asymptotic diversity of SC NOMA systems whereas the asymptotic diversity of MC NOMA systems, suffering from RX IQI, is always zero. Moreover, it is shown that for both SC and MC NOMA systems, the first sorted user appears more robust to IQI, which indicates that higher order users are more sensitive to the considered impairment.

Keywords

  • Fading channels, hardware impairments, I/Q imbalance, Interference, NOMA, Non-orthogonal multiple access, OFDM, outage probability, Radio frequency, Signal to noise ratio, Transceivers

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