Network Code Design for Orthogonal Two-hop Network with Broadcasting Relay: A Joint Source-Channel-Network Coding Approach

TL;DR

This paper proposes a nonlinear network coding scheme for orthogonal two-hop wireless networks with broadcasting relays, significantly reducing distortion in source transmission compared to linear codes, especially in complexity-constrained scenarios.

Contribution

It introduces a novel nonlinear network coding design that minimizes average distortion, outperforming existing linear coding methods in two-hop relay networks.

Findings

Nonlinear network codes outperform linear codes in distortion reduction.

The proposed algorithm efficiently designs network codes considering source-channel constraints.

Numerical results validate the effectiveness of the nonlinear coding scheme.

Abstract

This paper addresses network code design for robust transmission of sources over an orthogonal two-hop wireless network with a broadcasting relay. The network consists of multiple sources and destinations in which each destination, benefiting the relay signal, intends to decode a subset of the sources. Two special instances of this network are orthogonal broadcast relay channel and the orthogonal multiple access relay channel. The focus is on complexity constrained scenarios, e.g., for wireless sensor networks, where channel coding is practically imperfect. Taking a source-channel and network coding approach, we design the network code (mapping) at the relay such that the average reconstruction distortion at the destinations is minimized. To this end, by decomposing the distortion into its components, an efficient design algorithm is proposed. The resulting network code is nonlinear and substantially outperforms the best performing linear network code. A motivating formulation of a family of structured nonlinear network codes is also presented. Numerical results and comparison with linear network coding at the relay and the corresponding distortion-power bound demonstrate the effectiveness of the proposed schemes and a promising research direction.