Performance analysis of relay channel with amplify-and-forward in cooperative communication system

Cooperative communication has been proposed recently to offer the possibility of wireless communication systems to explore the inherent spatial diversity in relay channels. In this work we consider a scenario where a base station (source) transmits information to a user (destination) via a relay with amplify-and-forward technique. Using MPSK modulation, we first derive a closed-form symbol error rate (SER) formulation and corresponding lower bound which converges to the same limit as the theoretical upper bound in high signal to noise ratio (SNR). And we then minimize the SER by applying optimal power allocation technique (OPA) with mean channel gains. Simulation results show that our scheme outperforms the equal power allocation scheme in high SNR with a good performance improvement.