Combined Linear and Nonlinear Multiuser Detector for CDMA Systems with Parity Bit Selected Spreading Sequences

摘要

A combined linear and nonlinear multiuser detector for direct sequence code-division multiple-access (DS/CDMA) systems with parity bit selected spreading sequences in synchronous channels is proposed in this paper. In a CDMA system with parity bit selected spreading sequences (CDMA/PB), the spreading code used by each user depends on the transmitted data bits and it is selected from a set of mutually orthogonal spreading waveforms allocated to each user. A linear multiuser detector combined with a nonlinear multistage parallel interference cancellation (PIC) detector is used in this paper to mitigate the effect of multiple access interference (MAI). The simulation results show that, the Bit Error Rate (BER) performance of the proposed system is much better than the PIC detector as well as the conventional un-coded CDMA systems.