Iterative semi-blind multiuser detection for turbo-coded MC-CDMA system with space-time transmit diversity

Iterative multiuser detection and space-time coding are two promising techniques to increase the capacity and performance of coded multiuser systems in wireless channels. In this paper, we consider the design of iterative receivers for space-time block coded (STBC) multicarrier CDMA (MC-CDMA) uplink system, in the presence of both intracell and intercell interference. Two forms of iterative semi-blind multiuser receivers are proposed. The first is based on minimum mean square error criterion and the second is a hybrid scheme, based on a combination of parallel interference cancellation and linear multiuser detection. These receivers are derived using subspace approach, which utilize known users´ information for the computation of log-likelihood ratios (LLRs), while blindly suppressing the unknown interference. The LLRs are refined successively by using the extrinsic information available through decoding of all known users. Simulation results in a frequency-selective Rayleigh fading environment are presented to verify the performance of the proposed schemes.