Soft-input soft-output partial parallel interference cancellation for DS-CDMA systems

This paper presents a new soft-input soft-output multistage partial parallel interference cancellation (PPIC) detector for direct-sequence code-division multiple-access (DS-CDMA) systems. The proposed detector has a similar simple structure to the conventional PPIC scheme presented by Divsalar et al. (1998). A new way of reliability iterating is derived based on the single-user maximum a posteriori (MAP) criterion. At each stage, extrinsic information is extracted and then used as the a priori information for the next stage. Extensive computer simulations have shown that the proposed approach is capable of offering a good performance gain over the conventional PPIC scheme and some other well-known multiuser detectors, especially when the system load is heavy