Multiuser receiver scheme for full-rate space-time coded CDMA system with imperfect estimation

Abstract

By introducing a full-rate space–time coding (STC) scheme, a synchronous CDMA (code division multiple access) system with full-rate STC is given, and the corresponding uplink performance is investigated in Rayleigh fading channel with imperfect estimation. Considering that existing STC-CDMA system has high decoding complexity, low-complexity multiuser receiver schemes are developed for perfect and imperfect estimations, respectively. The schemes can make full use of the complex orthogonality of STC to reduce the high decoding complexity of the existing scheme, and have linear decoding complexity compared with the existing scheme with exponential decoding complexity. Moreover, the proposed schemes can achieve almost the same performance as the existing scheme. Compared with full-diversity STC-CDMA, the given full-rate STC-CDMA can achieve full data rate, low complexity, and partial diversity, and form efficient spatial interleaving. Thus, the concatenation of channel coding can effectively compensate for the performance loss due to partial diversity. Simulation results show that the full-rate STC-CDMA has lower bit error rate (BER) than full-diversity STC-CDMA systems under the same system throughput and concatenation of channel code. Moreover, the system BER with imperfect estimation are worse than that with perfect estimation due to the estimation error, which implies that the developed multiuser receiver schemes are valid and reasonable. Copyright © 2010 John Wiley & Sons, Ltd. (Based on the imperfect estimation information, a multiuse receiver scheme for full-rate space-time coded CDMA system with estimation error is developed in Rayleigh fading channel. This scheme includes perfect estimation as a special case. It has a lower implement complexity than the existing scheme, and can obtain almost the same performance.)