Cooperative RTS/CTS MAC with relay selection in distributed wireless networks

This paper proposes a cooperative multiple access protocol based on the distributed coordination function (DCF) request-to-send/clear-to-send (RTS/CTS) scheme for distributed wireless networks. It answers three key questions concerning cooperation from the network perspective, namely when to cooperate, whom to cooperate with and how to protect cooperative transmissions. According to our protocol, the cooperation is initiated only if the direct transmission fails. An optimal relay node is selected in a distributed manner according to instantaneous relay channel conditions without prior information or extra signaling among relay candidates in the network. An additional three-way handshake is introduced to protect cooperative retransmissions against the hidden terminal problem. Both analysis and simulation results show that significant improvement in throughput and packet delivery rate can be achieved using the proposed cooperative protocol.