Blind adaptive multiuser detection over ISI channels with channel estimation

Blind adaptive multi-user detection for DS-CDMA signals over an ISI limited channel is considered. The presence of ISI leads to significant mismatch between the the received signature vector and the transmitted code. Adaptive detectors designed for AWGN channels yield unacceptable performance due to this mismatch, unless equipped with a channel estimator. Previously, some methods that bypass explicit channel estimation have been proposed-these are shown to perform inadequately in general. This paper develops a channel estimation based blind adaptive detector that utilizes an efficient subspace tracker. The proposed scheme out-performs some of the existing methods (notably those without channel estimation) at the expense of modest increase in complexity.