Performance analysis for two-user Alamouti coded MIMO system with the PIC group decoding

Currently the research of multi-user MIMO system mainly focuses on the analysis of channel capacity. Low complexity is also attractive to the implementation of a receiver, and thus interference cancellation decoding is often adopted in practice. Partial Interference Cancellation (PIC) group decoding is one effective decoding algorithm for point-to-point MIMO systems which addressing the complexity and rate tradeoff very well. Since the decoding complexity of multi-user MIMO systems with the Maximum Likelihood (ML) decoding is very hign, PIC group decoding is a good choice for it. To clarify the performance of PIC group decoding when used in multi-user cases, this paper first derives the diversity order of two-user Alamouti coded MIMO systems with this decoding. For a two-user Alamouti coded MIMO system with N antennas at the receiver, the diversity order is 2 (N - 1) with the PIC group decoding. The conclusion can be easily extended to K-user cases, and achieve the diversity order of 2 (N - K + 1). Simulation results confirms the analytical derivation.