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.