Compute-Forward Multiple Access for Gaussian Fast Fading Channels

Fuente: arXiv
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Autori principali: Zhang, Lanwei, Evans, Jamie, Zhu, Jingge
Natura: Preprint
Pubblicazione: 2024
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author Zhang, Lanwei
Evans, Jamie
Zhu, Jingge
author_facet Zhang, Lanwei
Evans, Jamie
Zhu, Jingge
contents Compute-forward multiple access (CFMA) is a transmission strategy which allows the receiver in a multiple access channel (MAC) to first decode linear combinations of the transmitted signals and then solve for individual messages. Compared to existing MAC strategies such as joint decoding or successive interference cancellation (SIC), CFMA was shown to achieve the MAC capacity region for fixed channels under certain signal-to-noise (SNR) conditions without time-sharing using only single-user decoders. This paper studies the CFMA scheme for a two-user Gaussian fast fading MAC with channel state information only available at the receiver (CSIR). We develop appropriate lattice decoding schemes for the fading MAC and derive the achievable rate pairs for decoding linear combinations of codewords with any integer coefficients. We give a sufficient and necessary condition under which the proposed scheme can achieve the ergodic sum capacity. Furthermore, we investigate the impact of channel statistics on the capacity achievability of the CFMA scheme. In general, the sum capacity is achievable if the channel variance is small compared to the mean value of the channel strengths. Various numerical results are presented to illustrate the theoretical findings.
format Preprint
id arxiv_https___arxiv_org_abs_2404_19468
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Compute-Forward Multiple Access for Gaussian Fast Fading Channels
Zhang, Lanwei
Evans, Jamie
Zhu, Jingge
Information Theory
Compute-forward multiple access (CFMA) is a transmission strategy which allows the receiver in a multiple access channel (MAC) to first decode linear combinations of the transmitted signals and then solve for individual messages. Compared to existing MAC strategies such as joint decoding or successive interference cancellation (SIC), CFMA was shown to achieve the MAC capacity region for fixed channels under certain signal-to-noise (SNR) conditions without time-sharing using only single-user decoders. This paper studies the CFMA scheme for a two-user Gaussian fast fading MAC with channel state information only available at the receiver (CSIR). We develop appropriate lattice decoding schemes for the fading MAC and derive the achievable rate pairs for decoding linear combinations of codewords with any integer coefficients. We give a sufficient and necessary condition under which the proposed scheme can achieve the ergodic sum capacity. Furthermore, we investigate the impact of channel statistics on the capacity achievability of the CFMA scheme. In general, the sum capacity is achievable if the channel variance is small compared to the mean value of the channel strengths. Various numerical results are presented to illustrate the theoretical findings.
title Compute-Forward Multiple Access for Gaussian Fast Fading Channels
topic Information Theory
url https://arxiv.org/abs/2404.19468