Iterative multiuser detection for asynchronous CDMA with concatenated convolutional coding

In this paper, we propose iterative multiuser detectors for asynchronous co de-division multiple-access with parallel-concatenated convolutional codes (turbo codes) and with serially concatenated convolutional codes (SCCC). At each iteration we update and exchange the extrinsic information from multi user detector and channel decoders and regenerate soft information between constituent convolutional decoders. Simulation results show that with the p roposed structure, near-single-user performance can be achieved. We also pr opose two reduced-complexity techniques, i.e., the reduced-state iterative multiuser detector based on the T-MAP algorithm and the iterative interfere nce canceler based on a noise-whitening filter. Simulation results show sma ll performance degradation for these two techniques, particularly for the T -MAP receiver.