Compressed Error HARQ: Feedback Communication on Noise-Asymmetric Channels

TL;DR

This paper introduces Compressed Error HARQ, a novel feedback communication scheme designed for noise-asymmetric channels where the receiver's feedback link is of higher quality than the forward link, improving reliability and efficiency.

Contribution

It proposes a new hybrid ARQ scheme that leverages high-quality feedback in noise-asymmetric channels, combining hybrid ARQ with compressed error retransmission.

Findings

Significant improvements in reliability over conventional HARQ.

Enhanced latency and spectral efficiency in resource-constrained transmitters.

Effective adaptation to practical noise-asymmetric communication scenarios.

Abstract

In modern communication systems with feedback, there are increasingly more scenarios where the transmitter has much less power than the receiver (e.g., medical implant devices), which we refer to as noise-asymmetric channels. For such channels, the feedback link is of higher quality than the forward link. However, feedback schemes for cellular communications, such as hybrid ARQ, do not fully utilize the high-quality feedback link. To this end, we introduce Compressed Error Hybrid ARQ, a generalization of hybrid ARQ tailored for noise-asymmetric channels; the receiver sends its estimated message to the transmitter, and the transmitter harmoniously switches between hybrid ARQ and compressed error retransmission. We show that our proposed method significantly improves reliability, latency, and spectral efficiency compared to the conventional hybrid ARQ in various practical scenarios where the transmitter is resource-constrained.