Mapping functions for successive interference cancellation in CDMA

Cancellation schemes for CDMA detection are based on estimating and removing the inherent multiple access interference. Several strategies for estimating the interference have been suggested, In this paper, we consider successive cancellation based on linear soft-decision, hard-decision, and clipped soft-decision. The influence of the cancellation function on the corresponding decision boundaries is discussed and qualitative statements regarding BER performance is made. BER performance based on computer simulations are presented and the "optimal" choice of the parameters for the clipped soft-decision is considered.