The Half-Duplex AWGN Single-Relay Channel: Full Decoding or Partial Decoding?

TL;DR

This paper compares partial and complete decoding strategies in half-duplex Gaussian relay channels, showing partial decoding offers limited gains that diminish in key asymptotic scenarios, questioning the benefit of partial decoding.

Contribution

It analytically demonstrates the limited advantage of partial decoding over complete decoding in half-duplex relay channels, especially at high SNR or extreme relay positions.

Findings

Partial decoding outperforms complete decoding by at most 12.5%.

The rate gap diminishes when relay is near source or destination, or at low SNR.

Increasing SNR reduces the relative benefit of partial decoding.

Abstract

This paper compares the partial-decode-forward and the complete-decode-forward coding strategies for the half-duplex Gaussian single-relay channel. We analytically show that the rate achievable by partial-decode-forward outperforms that of the more straightforward complete-decode-forward by at most 12.5%. Furthermore, in the following asymptotic cases, the gap between the partial-decode-forward and the complete-decode-forward rates diminishes: (i) when the relay is close to the source, (ii) when the relay is close to the destination, and (iii) when the SNR is low. In addition, when the SNR increases, this gap, when normalized to the complete-decode-forward rate, also diminishes. Consequently, significant performance improvements are not achieved by optimizing the fraction of data the relay should decode and forward, over simply decoding the entire source message.