Matched–Filter Based Iterative Soft Decision Interference Cancellation Employing the Distribution of Interference

A well–known receiver strategy for CDMA transmission is iterative soft decision interference cancellation. For calculation of soft estimates, the distribution of residual interference is commonly assumed to be Gaussian. In this paper, we analyze matched–filter based iterative soft decision interference cancellation (MF ISDIC) when utilizing the actual probability density function (pdf) of residual interference. Additionally, a hybrid scheme is proposed, which approximates the actual pdf by considering only the strongest residual interferers accurately while the Gaussian assumption is applied on the weak residual interferers. It turns out, that the bit error ratio decreases already noticeably when only a small number of residual interferers is regarded according to its actual pdf. In fact, for the considered CDMA transmission we are able to lower the bit error ratio by 80% for high signal–to–noise ratios when modelling all residual interferers but the strongest 3 to be Gaussian distributed.