Receiver design for multiuser CDMA systems with space-time coding and imperfect state information

Considering that existing space-time coded CDMA (STC-CDMA) system has high decoding complexity, we design a low-complexity multiuser receiver scheme for imperfect channel state information (CSI) in this paper. The scheme can make full use of the complex orthogonality of STC to simplify the high decoding complexity of the existing scheme, and achieve almost the same performance as the existing scheme. Compared with full-diversity STC-CDMA, the given full-rate STC-CDMA can realize full data rate, low complexity and partial diversity, and form efficient spatial interleaving. Thus the system performance will be improved greatly when concatenated with the channel coding. Simulation results show that the designed receiver scheme is valid and reasonable, the multiuser system performance with imperfect CSI is worse than that with perfect CSI due to the estimation error. Moreover, the full-rate STC-CDMA has lower BER than those full-diversity STC-CDMA systems on the condition of same system throughput and concatenation of channel code.