A Simple Cooperative Diversity Method Based on Network Path Selection

TL;DR

This paper introduces a simple, relay-based cooperative diversity scheme that selects the best relay using local channel measurements, achieving high diversity gains without complex coding or topology information, suitable for 4G systems.

Contribution

A novel relay selection method that requires no topology info or relay communication, providing near-optimal diversity gains with minimal complexity.

Findings

Achieves diversity-multiplexing tradeoff similar to complex protocols.

Requires no explicit relay communication or topology knowledge.

Easily implementable in existing hardware for improved wireless performance.

Abstract

Cooperative diversity has been recently proposed as a way to form virtual antenna arrays that provide dramatic gains in slow fading wireless environments. However most of the proposed solutions require distributed space-time coding algorithms, the careful design of which is left for future investigation if there is more than one cooperative relay. We propose a novel scheme, that alleviates these problems and provides diversity gains on the order of the number of relays in the network. Our scheme first selects the best relay from a set of M available relays and then uses this best relay for cooperation between the source and the destination. We develop and analyze a distributed method to select the best relay that requires no topology information and is based on local measurements of the instantaneous channel conditions. This method also requires no explicit communication among the relays. The success (or failure) to select the best available path depends on the statistics of the wireless channel, and a methodology to evaluate performance for any kind of wireless channel statistics, is provided. Information theoretic analysis of outage probability shows that our scheme achieves the same diversity-multiplexing tradeoff as achieved by more complex protocols, where coordination and distributed space-time coding for M nodes is required, such as those proposed in [7]. The simplicity of the technique, allows for immediate implementation in existing radio hardware and its adoption could provide for improved flexibility, reliability and efficiency in future 4G wireless systems.