Distributed quasi-orthogonal space-time coding for two-way wireless relay networks

The contribution in this paper is to consider distributed quasi orthogonal space-time block coding (D-QO-STBC) for two-way (TW) wireless relay networks. In particular we exploit a two time slot protocol and both open-loop and closed-loop D-QO-STBC with full cooperative diversity. In the open-loop approach constellation rotation is exploited to improve performance, whereas two feedback terms are used in the closed-loop schemes. Our end-to-end bit error rate simulations show that TW closed-loop D-QO-STBC and rotated open-loop D-QO-STBC are approximately 8 dB and 7.5 dB better than the distributed Alamouti TW approach at 10^-4 bit error rate (BER), which confirms the advantage of four relay schemes in relay networks.