Distributed relay selection strategy based on source-relay channel

Recent results on cooperative networks have shown great potential in their ability to improve the system performance in the presence of fading channels by using different users´ antennas. However, traditional centralized relays selection needs considerable overhead and signaling to exchange the channel state information. In this paper, we propose a simple “ Amplify and Forward” distributed method to find the best source-relay path from a set of possible cooperating relays. The method requires no communication among the relays, assumes no prior knowledge of network geometry and is based only on instantaneous source-relay wireless channel measurements. Each relay compares its source-relay SNR with a threshold and decides to participate or not to the communication independently of other relays decisions. The threshold is chosen by maximizing the probability to select only one relay. Through simulations we show that the proposed threshold method achieves high capacity gains while keeping the outage probability at a reasonable level.