Differential Modulation and Selective Combining for Multiple-Relay Networks

In this paper, we consider a multiple-relay network. We propose differential modulation at each communication node and selective combining method at the receiver. As both differential modulation and the selective combining do not require the full channel state information, the system design is greatly simplified without compromising much of the system performance. The average BER for this multiple-relay system with estimation-and- forward signaling protocol at the relay nodes is derived. In the analysis, we take into account the effect of imperfect estimation at the relay nodes, by replacing each of the source-relay-destination links with an equivalent relay-destination link. From the performance analysis, we conclude that this multiple-relay system with selective combiner can achieve full diversity. The analysis is also verified by simulation results.