Parity Forwarding for Multiple-Relay Networks

TL;DR

This paper introduces a parity forwarding relaying strategy for multirelay networks that enhances achievable rates by allowing relays to decode selective messages, leading to capacity achievement in certain degraded networks.

Contribution

It proposes a novel parity forwarding protocol with a tree-structured characterization and derives closed-form achievable rate expressions, improving upon existing decode-and-forward strategies.

Findings

Parity forwarding improves achievable rates in multirelay networks.

The protocol is capacity achieving for certain degraded relay networks.

A tree structure characterizes a broad class of parity forwarding protocols.

Abstract

This paper proposes a relaying strategy for the multiple-relay network in which each relay decodes a selection of transmitted messages by other transmitting terminals, and forwards parities of the decoded codewords. This protocol improves the previously known achievable rate of the decode-and-forward (DF) strategy for multirelay networks by allowing relays to decode only a selection of messages from relays with strong links to it. Hence, each relay may have several choices as to which messages to decode, and for a given network many different parity forwarding protocols may exist. A tree structure is devised to characterize a class of parity forwarding protocols for an arbitrary multirelay network. Based on this tree structure, closed-form expressions for the achievable rates of these DF schemes are derived. It is shown that parity forwarding is capacity achieving for new forms of degraded relay networks.