A Lightweight Selection Cooperation Protocol with Multiple Available Best Relays

Selection cooperation has shown to be a practical cooperative strategy for wireless networks. In order to obtain full diversity gain, conventional selection cooperation schemes must select the node with the maximum relay-destination channel as the best relay, which restricts the choice of relay selection for the system. To overcome this limitation, we propose a lightweight selection cooperation protocol without requiring the radio of nodes to perform combining reception. Through outage probability and diversity-multiplexing tradeoff (DMT) analysis, we reveal an interesting fact that choosing any node that successfully receives the message from the source and the feedback frame from the destination as the best relay, the protocol always achieves the full diversity order and the optimal DMT. This result establishes a framework for obtaining multiple optimization objectives in selection cooperation networks. As an illustrative example, we then develop two best relay selection methods for relay balance without sacrificing the full diversity order. Simulation results demonstrate the remarkable performance and balance effect of the proposed protocol and selection methods.