Performance analysis of decode-and-forward relaying with selection combining

Distributed spatial diversity systems utilize multiple communication nodes to create independent signal replicas that are combined at the destination. Practical diversity receivers often employ simple combining techniques especially if comparable performance to more complex optimum combining can be achieved. The performance of decode-and-forward relaying that uses selection combining is investigated. In particular, a closed-form expression for the outage probability of a system with an arbitrary number of relay nodes is derived. By comparing the performance of a system that uses selection combining to one that uses optimum maximal ratio combining, it is shown that the performance loss due to using a less complex combiner is not substantial.