Performance of dual-hop multi-antenna systems with fixed gain amplify-and-forward relay selection

The performance of amplify-and-forward relaying in Rayleigh channels is explored for a dual-hop transmission system in which a transmission source selects one of several relays based upon instantaneous SNR (signal to noise ratio) to transmit a data packet to a destination receiver. Both source and receiver devices have multiple antennas, employing beamforming for transmission and MRC (maximal ratio combining) for reception. The chosen relay performs fixed gain forwarding. Closed form solutions for several performance measures are derived for this practical system, and the system is studied in terms of outage probability and symbol error rate which are verified through simulation. Several implementation alternatives are explored to note performance trade-offs, particularly between number of antennas and number of relays.