Achievable Performance Improvements Provided by Cooperative Diversity

This paper examines the achievable performance gains when a particular class of cooperative relaying known as best-select is employed. In essence, best-select seeks to improve performance by exploiting diversity. We examine several topologies as well as the case when the set of nodes available for forwarding goes to infinity. Determining the performance is complicated by the correlation of the channel gains between nearby channels (i.e., when the receivers are nearby and the transmitters are nearby). This challenge is overcome by modeling the channels as spatially continuous diffusion processes and as a random field and then using a Poisson clumping heuristic. In the example network and metric studied, it is found that in the limit, node cooperation can provide an increase in the end-to-end performance by 35 dB (i.e., a factor of ∼3000) in a 5-hop network. This result motivates further work in the design of multihop cooperative protocols.