An adaptive decision feedback PIC for asynchronous DS-CDMA system

Abstract

Parallel interference cancellation (PIC) detector has the potential for further performance improvement for direct-sequence code-division multiple access (DS-CDMA) system, because it estimates and subtracts the interference from the received signal. Its performance depends on the accuracy of the data estimation. In the conventional PIC detector, the data estimation is based on the matched filter, which results in poor performance, thus limiting the performance of the PIC detector. In this paper, an adaptive decision feedback PIC detector is proposed, which uses blind adaptive minimum mean square error (MMSE) detector for data estimation in each stage and uses the data estimates in the final stage to update the adaptive filters in the previous stages. This decision feedback scheme is shown to be effective and have improved performance especially in the asynchronous case.