Space-time power optimization of variable-rate space-time block codes based on successive interference cancellation

Based on a zero-forcing with successive interference cancellation (ZFSIC) method, we construct variable-rate space-time block codes (STBCs) for two, three, and four transmit antennas in Rayleigh fading channels. Considering the error-propagation effect in the ZFSIC scheme, we analyze the bit-error rate (BER) and optimize the transmit power so that the average BER is minimized. Unlike the approach based on zero-forcing (ZF), the method adopted in this paper can construct variable-rate STBCs even when the receive antennas are fewer than the transmit antennas. In addition, to improve the BERs further, we propose space-time power optimization. Numerical results show that the codes presented in this paper provide much lower BERs, compared with the codes developed by Kim and Tarokh.