Improving diversity of relay channels: Beamforming and relay selection

In this paper, the performance of various beamforming and relay selection schemes for fading relay channels, are investigated. Beamforming schemes that maximize the diversity of the system for amplify&forward (AF) and decode&forward (DF) methods, are proposed. In addition, relay selection algorithms are proposed for both methods and compared to previous works. For AF method, better performance is obtained by transmitting with less power as opposed to cancelling the worst relay according to proposed relay selection criteria. In contrast, cancelling the worst relay, yields better performance for DF method. In both cases, better performance in bit-error rate is obtained compared to ldquoBletsas algorithmrdquo.