Compress-Forward without Wyner-Ziv Binning for the One-Way and Two-Way Relay Channels

TL;DR

This paper investigates a compress-forward relaying scheme without Wyner-Ziv binning, showing it achieves the same rates as traditional methods in one-way channels and offers larger rate regions in two-way channels, with reduced delay.

Contribution

It introduces a binning-free compress-forward scheme for relay channels, demonstrating its effectiveness and advantages over traditional binning-based schemes in certain scenarios.

Findings

Achieves same rate as binning-based scheme in one-way relay channels.

Achieves larger rate region in two-way relay channels with asymmetry.

Reduces delay compared to noisy network coding.

Abstract

We consider the role of Wyner-Ziv binning in compress-forward for relay channels. In the one-way relay channel, we analyze a compress-forward scheme without Wyner- Ziv binning but with joint decoding of both the message and compression index. It achieves the same rate as the original compress-forward scheme with binning and successive decoding. Therefore, binning helps reduce decoding complexity by allowing successive decoding, but has no impact on achievable rate for the one-way relay channel. On the other hand, no binning simplifies relay operation. By extending compress-forward without binning to the two-way relay channel, we can achieve a larger rate region than the original compress-forward scheme when the channel is asymmetric for the two users. Binning and successive decoding limits the compression rate to match the weaker of the channels from relay to two users, whereas without binning, this restriction no longer applies. Compared with noisy network coding, compress-forward without binning achieves the same rate region in certain Gaussian channel configurations, and it has much less delay. This work is a step toward understanding the role of Wyner-Ziv binning in compress-forward relaying.