Asynchronous Cooperative Communications with STBC Coded Single Carrier Block Transmission

Conventional cooperative communication schemes suffer from asynchronous relay transmissions of distributed relay nodes, which can destroy the deliberately designed code structure and result in severe diversity gain loss. In the paper, we propose a cooperative scheme based on the single carrier block transmission (SCBT) technique that is robust to asynchronous relay transmissions. By introducing the orthogonal structure in the frequency domain and deploying the frequency domain equalizer (FDE), cooperative diversity can be achieved. Moreover, a novel random cyclic delay diversity (CDD) technique is developed so that a higher cooperative diversity gain can be achieved when more than 2 relay nodes are available. The proposed scheme is independent of the number of relay nodes and does not need to exchange any side information among nodes. The proposed scheme can inherently support both the amplify-and-forward (AF) and decode-and-forward (DF) cooperative mechanisms.