On the impact of soft decision functions on the performance of multistage parallel interference cancelers for CDMA systems

Since CDMA systems in multipath environments suffer from multiple access interference (MAI) multiuser detection (MUD) schemes are used in the receivers. Parallel interference cancellation (PIC) is an iterative nonlinear method to combat MAI with good performance and relatively low computational complexity, which is crucial for practical implementation. In this paper the decision function for the symbol estimates between these PIC stages is investigated for a multi-carrier spread-spectrum frequency code division multiple access (MC-SS FCDMA) system. Monte-Carlo simulations show the impact of the decision-function on the performance for several parameters.