Performance Analysis of Relay Selection Schemes for Cooperative Communications

Outage probabilities of all relays selection scheme and opportunistic relaying selection scheme based on decode-and-forward(DF) protocol were analyzed.Especially,exact closed-form results of the outage probability for the two schemes over Rayleigh fading channels were derived.Further investigation of the outage performance was made and asymptotic expressions for outage probability were obtained in the high signal-to-noise ratio(SNR) regime.Theoretical analysis and numerical simulation results show that the outage results of the two methods are equal in high SNR or in the case that the perfor-mance of relay-destination channels is better than that of source-relay channels.The outage performance of all relays selection scheme is better than that of opportunistic relaying selection scheme when the perfor-mance of channels from the source to relays is better than that of the channels form relays to the destination.