BER performance analyses of weighted multistage non-linear parallel interference cancellation based space-time block code

Space-time block code (STBC) has a good BER performance. In 3GPP FDD specifications, space time transmit diversity (STTD) employs STBC to maintain orthogonality between the two antennas in order to avoid self-interference in fading channels. However, the capacity of multiuser STBC systems is still severely affected by multiple access interference (MAI) and interpath interference (IPI). Fortunately, nonlinear parallel interference cancellation (NPIC) can effectively reduce MAI and IPI with simple signal processing. And for the small spreading factor systems, weighted NPIC (WNPIC) technique provides a good solution. In order to alleviate the influence of the MAI and IPI of multiuser STBC systems under the frequency-selective Rayleigh fading channel, WNPIC based space-time block code (WNPIC based STBC) scheme is proposed firstly in this paper. And then the error probability of the WNPIC based STBC is analyzed theoretically. From our analyses, RAKE based STBC can be regarded as 0th stage WNPIC based STBC whose weighted factors are one. Later, to further evaluate the proposed scheme and verify our analyses, some simulation resulted are achieved. These simulation results show us the optimum weighted factors under different user environments and the multiuser BER performance of simple (RAKE) STBC systems, NPIC based STBC, WNPIC based STBC systems.