Outage behavior of cooperative diversity schemes with relay selection

Abstract

New digital communication standards have been raised to support the dramatic rise of the capacity demand and to provide the comprehensive coverage. Thereby, many researchers have taken on the technical challenges in the part of wireless interface, which is the bottleneck of a communication system, due to its limited channel. The important idea that can improve the system in a major way is to use cooperative diversity, especially when the coherence time is too long compared to the transmission block, and the interleaver technique or channel coding is not long enough to combat the fading efficiently. In this thesis, we are particularly interested in the cooperative diversity schemes that employ multiple relay nodes with relay selection protocol. For systems employing diversity techniques, the outage probability and the outage capacity are the important figures of merit. We analyze both the outage probability and the outage capacity for such cooperative diversity schemes. The analyses show many insights, for example, there exists a signal-to-noise ratio threshold, below which some cooperative diversity schemes outperform direct communication. The obtained expressions are exact, simple, and applicable to arbitrary network topologies and signal-to-noise ratios in Rayleigh fading channels. Our results can serve as guidelines for efficient system design of cooperative diversity schemes and deployment of cooperative networks.