Iterative multiuser detection for turbo-coded synchronous CDMA in Gaussian and non-Gaussian impulsive noise

In this paper, we develop an iterative multiuser receiver for decoding Turbo coded synchronous CDMA signals in both Gaussian and non-Gaussian noise. A soft-input soft-output non-linear multiuser detector is combined with a set of single user channel decoders in an iterative detection/decoding structure. The non-linear multiuser detector utilizes the prior probabilities of each user's bits to form soft estimates used for multiple access interference cancellation. The channel decoders perform Turbo code decoding and produce posterior probabilities which are fed back to the multiuser detector for use as prior probabilities. Simulation results show that the proposed multiuser receiver performs well in both Gaussian and non-Gaussian noise. In particular, single user Turbo code performance can be approached within a few iterations with medium to low cross-correlation (0:5).