Relay vs. User Cooperation in Time-Duplexed Multiaccess Networks

TL;DR

This paper compares user cooperation and relay cooperation in multiaccess networks, analyzing outage probabilities and energy efficiency, revealing that relay cooperation can be more energy-efficient especially at low SNR despite lower diversity.

Contribution

It provides a comprehensive comparison of user and relay cooperation considering both outage performance and energy costs in multiaccess networks.

Findings

Relay cooperation achieves higher energy efficiency at low SNR.

User cooperation offers higher diversity gains with K and 2 for K users.

Relay cooperation can outperform user cooperation in energy consumption.

Abstract

The performance of user-cooperation in a multi-access network is compared to that of using a wireless relay. Using the total transmit and processing power consumed at all nodes as a cost metric, the outage probabilities achieved by dynamic decode-and-forward (DDF) and amplify-and-forward (AF) are compared for the two networks. A geometry-inclusive high signal-to-noise ratio (SNR) outage analysis in conjunction with area-averaged numerical simulations shows that user and relay cooperation achieve a maximum diversity of K and 2 respectively for a K-user multiaccess network under both DDF and AF. However, when accounting for energy costs of processing and communication, relay cooperation can be more energy efficient than user cooperation, i.e., relay cooperation achieves coding (SNR) gains, particularly in the low SNR regime, that override the diversity advantage of user cooperation.