Adaptive transmission in cooperative wireless communications

In this paper, we propose and investigate a decentralized adaptive transmission technique for cooperative wireless communications. A number of relays adaptively switch between two transmission modes: Alamouti diversity and spatial multiplexing. The relays may exploit Amplify-and-Forward (AF) or Decode-and-Forward (DF) transmission technique. The performances of the decentralized adaptive transmission technique based on channel quality estimations are evaluated and compared to the centralized adaptive transmission technique based on error probability minimization with limited feedback from the destination. Even though the simulations show that the Bit-Error-Rate (BER) performances of the decentralized adaptive approach are close to that of the centralized adaptive technique, our proposed technique provides less communications between the nodes and hence improves the communication in terms of delay and power consumption.