Performance analysis of distributed MRC combining with a single amplify-and-forward relay over Rayleigh fading channels

This paper considers a dual-hop amplify-and-forward (AF) cooperative diversity system where a source node communicates with a destination node directly and indirectly (through a single antenna relay) over independent and flat Rayleigh fading channels. A comprehensive approach for analyzing the error performance of phase shift keying (PSK) modulations and quadrature amplitude modulation (QAM) is presented for the AF relay network employing distributed maximal-ratio combining (MRC) at the destination. Using a general two-parameter received signal-to-noise ratio (SNR) model, we derive in particular the probability density function (PDF) of the equivalent SNR for the dual-hop relay link in a unified manner that encompasses two specific AF relay configurations. This PDF is then used to derive a pair of closed-form expressions for the average bit error probability (BEP) of coherent modulation schemes. Simulation results are also provided to verify the accuracy of the derived expressions.