Cooperative Diversity Based on Alamouti Space-Time Code

Cooperative diversity enables single-antenna terminals in a multi-user environment to share their antennas so as to form a virtual antenna array and achieve spatial diversity in a distributed fashion. To improve the bandwidth efficiency of classical scheme, a novel cooperative diversity scheme based on space-time coding is proposed in this work. With the selection decode-and-forward (SDF) relaying protocol, a tight closed form approximate bit error rate(BER) for BPSK constellation is derived, and the effect of symmetric and asymmetric inter-user channels of various qualities on system performance is studied. Theoretical and simulation results show that the proposed scheme offers substantial performance gain over non-cooperative scheme under the scenarios of interest and the full diversity order of two is achieved at high inter-user channel signal-to-noise ratio(SNR). Compared with the classical cooperative diversity scheme, the proposed scheme provides better bandwidth efficiency with acceptable performance loss.