Improving distributed space-time coding through combining at the multiple-antenna relay

Distributed space-time coding (DSTC) is a cooperative scheme proposed for wireless relay networks that achieves full diversity when the transmit power is infinitely high. In this paper, we propose to employ maximum-ratio combining (MRC) at the multiple-antenna relay to improve the performance of DSTC. Simulations and analysis show that the new scheme achieves a much better performance in relay networks than DSTC. In some network scenarios, it can even improve the scaling of the error rate with the transmit power. Furthermore, the new scheme requires a shorter training interval than DSTC.