Adaptive group-blind multiuser detection based on a new subspace tracking algorithm

Recently, Wang and Host-Madsen developed group-blind multiuser detectors fo r use in code-division multiple-access (CDMA) uplink environments in which the base station receiver has the knowledge of the spreading sequences of a il the users within the cell, but not that of the users from other cells. Y u and Host-Madsen later developed an adaptive version of this detector for synchronous CDMA channels. In this letter, we develop a new low-complexity, high-performance subspace tracking algorithm and apply it to adaptive grou p-blind multiuser detection in asynchronous multipath CDMA channels. The de tector can track changes in the number of users and their composite signatu re waveforms, We present steady-state performance as well as the ability of the receiver to track changes in the signal subspace, We also address the performance gain of the group-blind detector over its blind counterpart for this application.