Relay Selection Strategies for Distributed Space-Time Cooperative Systems Over Wireless Ad-Hoc Networks

We propose several relay selection strategies for distributed space-time cooperative systems, in which the Alamouti scheme is used. Our strategies select the best two nodes among the source and all relays to assist the packet transmissions from the source to the destination. In the amplify-and-forward mode, we develop an efficient algorithm to select the optimal cooperative nodes which can maximize the instantaneous signal-to-noise ratio at the destination. Under the decode-and-forward mode, our relay selection strategies depend on the successful decoding results at the relays. We design our schemes by considering both cases with and without CRC. In addition, we integrate the request- to-send/clear-to-send mechanism into our proposed system and analyze the system throughputs. The simulation results show that our proposed strategies can significantly improve the system throughput and achieve the diversity gain as compared to the conventional existing schemes.