Diversity, Coding, and Multiplexing Trade-Off of Network-Coded Cooperative Wireless Networks

TL;DR

This paper analyzes the trade-offs between diversity, coding, and multiplexing in network-coded cooperative wireless networks, revealing how relay behavior impacts overall system performance under practical constraints.

Contribution

It provides an accurate analysis of ABEP in network-coded cooperative systems with realistic constraints, highlighting the effects of relay strategies on diversity and coding gains.

Findings

Network coding increases throughput but reduces diversity and coding gains.

Relays forwarding network-coded data offer no diversity or coding gain for source nodes.

Binary network coding is more beneficial when relays do not mix their own data.

Abstract

In this paper, we study the performance of network-coded cooperative diversity systems with practical communication constraints. More specifically, we investigate the interplay between diversity, coding, and multiplexing gain when the relay nodes do not act as dedicated repeaters, which only forward data packets transmitted by the sources, but they attempt to pursue their own interest by forwarding packets which contain a network-coded version of received and their own data. We provide a very accurate analysis of the Average Bit Error Probability (ABEP) for two network topologies with three and four nodes, when practical communication constraints, i.e., erroneous decoding at the relays and fading over all the wireless links, are taken into account. Furthermore, diversity and coding gain are studied, and advantages and disadvantages of cooperation and binary Network Coding (NC) are highlighted. Our results show that the throughput increase introduced by NC is offset by a loss of diversity and coding gain. It is shown that there is neither a coding nor a diversity gain for the source node when the relays forward a network-coded version of received and their own data. Compared to other results available in the literature, the conclusion is that binary NC seems to be more useful when the relay nodes act only on behalf of the source nodes, and do not mix their own packets to the received ones. Analytical derivation and findings are substantiated through extensive Monte Carlo simulations.