A New Achievability Scheme for the Relay Channel

TL;DR

This paper introduces a novel coding scheme for the relay channel that generalizes existing methods, allowing for better correlation preservation and potentially higher achievable communication rates.

Contribution

A new block Markov coding scheme for the relay channel that generalizes the Compress-And-Forward approach and enables correlation preservation between transmitter and relay inputs.

Findings

Potentially larger achievable rates than CAF scheme

Provides options for preserving input correlation

Generalizes the well-known CAF scheme

Abstract

In this paper, we propose a new coding scheme for the general relay channel. This coding scheme is in the form of a block Markov code. The transmitter uses a superposition Markov code. The relay compresses the received signal and maps the compressed version of the received signal into a codeword conditioned on the codeword of the previous block. The receiver performs joint decoding after it has received all of the B blocks. We show that this coding scheme can be viewed as a generalization of the well-known Compress-And-Forward (CAF) scheme proposed by Cover and El Gamal. Our coding scheme provides options for preserving the correlation between the channel inputs of the transmitter and the relay, which is not possible in the CAF scheme. Thus, our proposed scheme may potentially yield a larger achievable rate than the CAF scheme.