Zero-Delay Joint Source-Channel Coding for a Multivariate Gaussian on a Gaussian MAC

TL;DR

This paper introduces a novel zero-delay joint source-channel coding scheme for multivariate Gaussian sources over Gaussian MACs, demonstrating robust performance and near-optimality at high SNRs.

Contribution

It proposes a nonlinear hybrid discrete-analog scheme and a linear DQLC method, advancing zero-delay JSCC solutions with improved performance and robustness.

Findings

DQLC outperforms linear solutions at high SNRs

Performance gap remains constant at high SNRs

Scheme is robust against noise variations

Abstract

In this paper, communication of a Multivariate Gaussian over a Gaussian Multiple Access Channel is studied. Distributed zero-delay joint source-channel coding (JSCC) solutions to the problem are given. Both nonlinear and linear approaches are discussed. The performance upper bound (signal-to-distortion ratio) for arbitrary code length is also derived and Zero-delay cooperative JSCC is briefly addressed in order to provide an approximate bound on the performance of zero-delay schemes. The main contribution is a nonlinear hybrid discrete-analog JSSC scheme based on distributed quantization and a linear continuous mapping named Distributed Quantizer Linear Coder (DQLC). The DQLC has promising performance which improves with increasing correlation, and is robust against variations in noise level. The DQLC exhibits a constant gap to the performance upper bound as the signal-to-noise ratio (SNR) becomes large for any number of sources and values of correlation. Therefore it outperforms a linear solution (uncoded transmission) in any case when the SNR gets sufficiently large.