Hash-and-Forward Relaying for Two-Way Relay Channel

TL;DR

This paper introduces a hash-and-forward relaying scheme for two-way relay channels, demonstrating its potential to achieve capacity under certain conditions and providing a detailed coding scheme for binary adder channels.

Contribution

It proposes a novel hash-and-forward relaying method that does not decode at the relay, matching Shannon's inner-bound under specific conditions, and offers a capacity-achieving code for binary adder channels.

Findings

Hash-and-forward relaying can achieve the capacity region in certain two-way relay channels.

The proposed scheme matches Shannon's inner-bound under specific channel conditions.

A detailed coding scheme is provided for binary adder channels with additive noise.

Abstract

This paper considers a communication network comprised of two nodes, which have no mutual direct communication links, communicating two-way with the aid of a common relay node (RN), also known as separated two-way relay (TWR) channel. We first recall a cut-set outer bound for the set of rates in the context of this network topology assuming full-duplex transmission capabilities. Then, we derive a new achievable rate region based on hash-and-forward (HF) relaying where the RN does not attempt to decode but instead hashes its received signal, and show that under certain channel conditions it coincides with Shannon's inner-bound for the two-way channel [1]. Moreover, for binary adder TWR channel with additive noise at the nodes and the RN we provide a detailed capacity achieving coding scheme based on structure codes.