Relay selection vs. repetitive transmission cooperation: Analysis under Nakagami-m fading

The performance of dual-hop Decode-and-Forward relaying with relay selection (RS) and repetitive transmission is studied over Nakagami-m fading channels. Closed-form expressions for the moment generating function of RS-based transmission with maximal-ratio diversity at the destination and repetitive transmission with selection diversity (SD) are derived. We obtain the outage probability (OP) and the average symbol error probability (ASEP) for the following relaying schemes: repetitive transmission, pure RS-based transmission and a rate-selective scheme that utilizes the selected relay node only if it provides higher achievable rate than direct transmission. Performance results show that RS-based schemes always outperform the repetitive ones. Furthermore it is shown that in terms of ASEP pure RS is always beneficial, although in terms of OP the single-hop transmission outperforms dual-hop relaying if the source to destination channel is sufficiently strong.