Performance analysis of CDMA multi user systems when using space-time block coding and BPSK modulation

We analytically evaluate the performance of a CDMA multi user system when using multiple antennas and space-time block coding assuming Rayleigh fading. We develop a formula to calculate the symbol error probability of such a system in a downlink scenario. Our derivation is based on the BPSK modulation. Using the proposed formula we can well predict the performance of the system, and study the effect of different system parameters on the performance. The existence of such a mathematical formula for a communication system can help the system designer to choose the system parameters without resorting to simulation which is time consuming work.