On the Performance Analysis of a MIMO-Relaying Scheme With Space–Time Block Codes

This paper presents performance analysis of a cooperative multiple-input-multiple-output (MIMO) relaying system with a single relay. In this scheme, each link uses MIMO Alamouti space-time block coding (STBC) over Rayleigh flat-fading channels. The particularity of the proposed scheme is that, during a first time slot, the source node broadcasts each STBC to the relay and destination nodes. During the second time slot, the relay node amplifies-and-forwards (AF) the received STBCs. Finally, the receiver at the destination node exploits the diversity gain that is obtained through the direct and indirect links simultaneously by applying maximum ratio combining (MRC) on the received signals. Using the SNR for the direct link and an upper bound of the SNR for the indirect link, the moment-generating function (MGF) of the SNR for the cooperative link is derived. Since this MGF is based on an upper bound of the SNR, it is then employed to derive a lower bound of the symbol error probability (SEP) for a particular signal of M-ary quadrature-amplitude modulation (M-QAM). Subsequently, simulation results of the SEP are presented to illustrate the performance improvement given by the MIMO cooperative diversity system based on the STBC scheme.