Joint Compute and Forward for the Two Way Relay Channel with Spatially Coupled LDPC Codes

TL;DR

This paper introduces a joint compute and forward decoding scheme for the two way relay channel using spatially coupled LDPC codes, achieving optimal rates with a single encoder and decoder.

Contribution

It derives the exact performance of a message passing decoder for joint compute and forward with spatially coupled LDPC codes, demonstrating improved achievable rates.

Findings

Joint compute and forward can match the best known achievable rates.

Spatially coupled LDPC codes enable reliable decoding in this setting.

The proposed scheme simplifies encoding and decoding processes.

Abstract

We consider the design and analysis of coding schemes for the binary input two way relay channel with erasure noise. We are particularly interested in reliable physical layer network coding in which the relay performs perfect error correction prior to forwarding messages. The best known achievable rates for this problem can be achieved through either decode and forward or compute and forward relaying. We consider a decoding paradigm called joint compute and forward which we numerically show can achieve the best of these rates with a single encoder and decoder. This is accomplished by deriving the exact performance of a message passing decoder based on joint compute and forward for spatially coupled LDPC ensembles.