The Amplify-and-Forward Cooperative Uplink Using Multiple-Symbol Differential Sphere-Detection

It is widely recognized that the differential amplify-and-forward (DAF) transmission scheme is capable of providing a superior performance compared to classic direct transmissions employing differential detection in slow-fading channels and in fact it may even outperform coherent detection aided systems relying on realistic imperfect channel estimates. However, in reality the channels connecting the multiple nodes of a cooperative system typically become time-selective due to the relative mobility of the cooperating terminals. Hence, the performance gain achieved may erode as the environment becomes more time-selective. Hence in this paper, we specifically design the multiple-symbol based differential sphere detection (MSDSD) for the DAF-aided cooperative system, which is capable of achieving a significant performance gain for transmission over time-selective channels.