Semiblind multiuser detection based on subspace tracking

A novel adaptive semiblind multiuser detector based on subspace tracking is proposed for CDMA systems. Blind multiuser detectors consider only the in-cell users and neglect the inter-cell interference from out-of-cell users while semiblind multiuser detectors take into account both, intra-cell and inter-cell interference. Semiblind multiuser detectors are superior to blind multiuser detectors when the codes of some users are known to a base station e.g., codes of in-cell users vs. out-of-cell users. The proposed semiblind scheme does not require the knowledge of spreading codes of out-of-cell users. Compared to the existing blind and semiblind multiuser detectors, the proposed semiblind detector exhibits faster convergence, and is more robust in the case when the system is heavily loaded. If is also computationally less expensive