Abstract
The system under study is a convolutionally coded M-ary orthogonal DS-CDMA system in time-varying frequency selective Rayleigh fading channels. With emphasis on the development of several soft demodulation algorithms, we propose an iterative multi-function process integrating demodulation,decoding and multiuser detection in this paper. The performance of the proposed algorithms are evaluated numerically and proved to achieve substantial performance gain compared to the conventional demodulation and decoding scheme, especially when the soft demodulator is assisted by interference cancellation or suppression techniques.