Decode-forward and Compute-forward Coding Schemes for the Two-Way Relay Channel

TL;DR

This paper introduces two advanced coding schemes for the full-duplex two-way relay channel, combining decode-forward and compute-forward techniques to enhance data rates beyond existing methods.

Contribution

It proposes novel partial decode-forward and combined decode-forward and compute-forward schemes using rate-splitting and superposition coding for the two-way relay channel.

Findings

Partial decode-forward increases the rate region over decode-forward in Gaussian channels.

The combined scheme outperforms both decode-forward and compute-forward individually.

Superposition coding of Gaussian and lattice codes enables the relay to decode and compute more efficiently.

Abstract

We consider the full-duplex two-way relay channel with direct link between two users and propose two coding schemes: a partial decode-forward scheme, and a combined decode-forward and compute-forward scheme. Both schemes use rate-splitting and superposition coding at each user and generate codewords for each node independently. When applied to the Gaussian channel, partial decode-forward can strictly increase the rate region over decode-forward, which is opposite to the one-way relay channel. The combined scheme uses superposition coding of both Gaussian and lattice codes to allow the relay to decode the Gaussian parts and compute the lattice parts. This scheme can also achieve new rates and outperform both decode-forward and compute-forward separately. These schemes are steps towards understanding the optimal coding.