Performance of space-time codes in the presence of spatial fading correlation

Previous work on space-time coding has been restricted to the idealistic case of uncorrelated spatial fading. In practice, however insufficient antenna spacing or lack of scattering cause the individual antennas to be correlated. In this paper we study the impact of spatial fading correlation on the performance of space-time codes. In particular we quantify the loss in diversity gain and coding gain as a function of angle spread and antenna spacing. We furthermore show that if a space-time code achieves full diversity in the uncorrelated case, the diversity order achieved in the correlated case is given by the product of the rank of the transmit correlation matrix and the rank of the receive correlation matrix. Finally, we provide simulation results demonstrating the impact of spatial fading correlation on the symbol error rate of space-time codes.