Cooperative amplify and forward in the presence of multiple selfish relays: Performance analysis

We consider the amplify-and-forward (AF) cooperative diversity scheme where a source node communicates with a destination with the help of multiple relay nodes. The conventional system model assumes all relay nodes have spontaneous willing to cooperate for data transmission. However, the relay has to consume its own resource (power and bandwidth) for achieving the diversity gain. Thus the usual cooperative assumption is unrealistic for autonomous users. Due to lack of a mechanism to ensure relaypsilas adherence to the cooperation strategy, the performance improvement may be degraded by selfish relays. In this paper, we investigate the performance of cooperative AF in the presence of multiple selfish users. The relay is assumed to mimic characteristics of an on-off channel where it exhibits random behaviors of cooperation and defection to hide its disposition. We derive the explicit expressions for the average bit error rate (BER) performance of cooperative diversity networks with multiple selfish relays. Our results indicate that multiple selfish relays can improve BER tremendously relative to a single selfish relay, if the multiple relays have proper selfish degree.