Selective Coding Strategy for Unicast Composite Networks

TL;DR

This paper introduces a dynamic coding strategy for unicast relay networks that allows relays to choose between compress-and-forward and decode-and-forward based on channel measurements, improving performance.

Contribution

A novel Selective Coding Strategy (SCS) enabling relays to adaptively select coding schemes based on channel conditions, extending Noisy Network Coding for mixed relay strategies.

Findings

SCS outperforms conventional fixed coding schemes in numerical tests.

The generalization of Noisy Network Coding incorporates mixed relay strategies.

Relays can leverage offset coding to enhance cooperation between DF and CF schemes.

Abstract

Consider a composite unicast relay network where the channel statistic is randomly drawn from a set of conditional distributions indexed by a random variable, which is assumed to be unknown at the source, fully known at the destination and only partly known at the relays. Commonly, the coding strategy at each relay is fixed regardless of its channel measurement. A novel coding for unicast composite networks with multiple relays is introduced. This enables the relays to select dynamically --based on its channel measurement-- the best coding scheme between compress-and-forward (CF) and decode-and-forward (DF). As a part of the main result, a generalization of Noisy Network Coding is shown for the case of unicast general networks where the relays are divided between those using DF and CF coding. Furthermore, the relays using DF scheme can exploit the help of those based on CF scheme via offset coding. It is demonstrated via numerical results that this novel coding, referred to as Selective Coding Strategy (SCS), outperforms conventional coding schemes.