Outage Analysis in a Cooperative System with Beamforming and Worst Relay Cancellation

In this paper, realizing full diversity in relay channels operating in decode and forward (DF) scheme is considered. In the proposed system, the worst relay according to a chosen criterion is cancelled while the remaining ones utilize beamforming. Both theoretical analysis, and experimental comparisons in bit error rate (BER) performance are given for the proposed system and the system where all relays are active. The scheme which cancels the worst relay achieves full diversity order which is demonstrated through outage probability (OP) upper bound. The derivation of the OP upper bound is carried out using order statistics. Simulations are performed for various numbers of relays and differential signal to noise ratios (DSNR) which are the differences in SNR between source-relay and relay-destination channels. This way, the full diversity order of the proposed system is validated experimentally. Moreover, it is observed that the proposed system achieves better performance in BER compared to the system with no cancellation.