Channel State Feedback over the MIMO-MAC

TL;DR

This paper develops low latency, low complexity feedback schemes for MIMO-MAC channels, introducing separated and joint source-channel methods, including a simple scalar quantization and QAM scheme that achieves optimal asymptotic performance for single-antenna users.

Contribution

It proposes a novel framework for channel state feedback, introducing simple yet effective coding schemes that outperform analog feedback and achieve theoretical limits.

Findings

Scalar quantization and uncoded QAM achieve asymptotic optimality for single-antenna users.

The proposed schemes outperform traditional analog feedback in MSE distortion.

Low latency and complexity are achieved with the new coding strategies.

Abstract

We consider the problem of designing low latency and low complexity schemes for channel state feedback over the MIMO-MAC (multiple-input multiple-output multiple access channel). We develop a framework for analyzing this problem in terms of minimizing the MSE distortion, and come up with separated source-channel schemes and joint source-channel schemes that perform better than analog feedback. We also develop a strikingly simple code design based on scalar quantization and uncoded QAM modulation that achieves the theoretical asymptotic performance limit of the separated approach with very low complexity and latency, in the case of single-antenna users.