Design of Distributed Space-Time Block Code for Two-Relay System over Frequency Selective Fading Channels

This paper proposes the distributed space-time block code (D-STBC) over frequency selective fading channel that achieves both spatial diversity gain and low decoding complexity with decoupling property in amplify-and-forward (AF) relay networks. These two goals are simultaneously achieved by our proposed code design, where the source permutates and conjugates the transmitted data before sending to the second relay. The diversity gain is investigated by analyzing the pairwise error probability (PEP) of the proposed scheme. In the analysis, we assume that one hop is line-of-sight (LOS) transmission modeled by Rician fading and the other hop is non-line-of-sight (NLOS) transmission experienced by Rayleigh fading. For each case, the PEP is derived based on the corresponding fading channel model.