Error rate analysis of quasi-orthogonal space–time block codes with power scaling

The exact pairwise error probability (PEP) of quasi-orthogonal space-time block codes (QSTBCs) employing the power scaling technique in quasi-static Rayleigh fading channels is derived. By utilising the derived PEP formula, the tight union upper bound on the bit error rate (BER) for the QSTBC with power scaling (PS-QSTBC) is evaluated and compared with the Monte Carlo simulation results to verify the analytical results that full diversity rate-1 transmission can be achieved. Furthermore, considering the closed-loop system, the optimal value of the power scaling factor is also investigated in terms of minimising the union bound on the BER.