Blind multiuser detection in W-CDMA systems with large delay spread

A two-stage blind multiuser antenna array detector is proposed for the uplink of a wideband CDMA system subject to large delay spread. It is shown that it is possible to identify the symbols of all users without knowledge of their codes, channels, or directions. The key idea is that low-rank decomposition of the three-dimensional (3-D) received data array can reduce the FIR multiple-input multiple-output (FIR-MIMO) CDMA problem into standard FIR single-input multiple-output (FIR-SIMO) problems.