Trellis-based multiuser detection for DS-CDMA systems in mismatched asynchronous flat-fading channels

The problem of multi-user detection in direct-sequence code-division multiple-access systems with channel state mismatch is addressed. An approximate maximum-likelihood criterion is derived based on knowledge of the statistical properties of the residual channel estimation errors. The time of arrival is assumed to be a constant during the time frame of interest. Errors in both timing information and fading coefficient information are assumed. A Viterbi-like recursive demodulation scheme is derived and analyzed. The performance of the new algorithm is studied via simulation and the development of performance bounds.