Distributed Space-Time Coding Based on Amplify-and-Forward Protocol

A distributed space-time coding (DSTC) scheme based on amplify-and-forward protocol (AF-DSTC) is proposed in this paper. The Alamouti code is used by the source and relay node. Without decoding and receding at relay node, this new scheme avoids the interference on destination due to the decision errors at the relay and reduces the power consumption. Moreover, we derive the approximate outage probability of AF-DSTC. Theoretical analysis and simulation results show that AF-DSTC outperforms the suboptimum detector of DSTC based on decode-and-forward protocol (DF-DSTC). When the SNR between source node and relay node is high enough, AF-DSTC provides the same performance as the ML detector of DF-DSTC before the BER floor of AF-DSTC occurs and achieves full diversity gain. In order to minimize the BER of AF-DSTC and achieve high diversity gain, we should choose the idle node which is close to the source node as relay node.