Iterative MMSE group-blind multiuser detection for a coded CDMA system

In this paper, we consider the problem of multiuser detection in the presence of users with unknown signature codes for a synchronous coded CDMA system. Interference suppression for unknown users is done by projecting the received signal on the null space of known users and then using eigenvalue decomposition and subspace techniques to derive a detector that cancels the known interference and successfully mitigates the unknown interference. Significant performance gains over detectors that ignore unknown users and treats them as noise is achieved.