Space-time adaptive interference-canceling equalizer for W-CDMA with known and unknown interference

Space-time parallel interference cancellation (ST-PIC) is an effective multi-stage multiuser detection scheme for wideband code-division multiple access (W-CDMA). However, the realization of ST-PIC requires accurate channel estimate, a sufficient number of stages, and knowledge of all user’s spreading waveforms. With inaccurate channel estimate or insufficient number of stages, the residual multiple access interference (MAI) degrades performance significantly. Furthermore, the performance of ST-PIC is also affected by the presence of interference for which the spreading waveforms are unknown. This paper introduces a new structure for enhancing the performance of ST-PIC in these situations. Simulation results show that a bit error rate (BER) reduction of as much as an order of magnitude is achievable using the proposed structure in the presence of strong MAI.