Group-Blind Multiuser Detectors for CDMA: Synchronous Systems

ABSTRACT We consider the problem of multiuser detection for CDMA (code division multiple access) systems where the codes of some users are known while others are unknown, group-blind multiuser detection. An example is at the base station of a cellular communication system with interference from both in-cell users, with known codes, and out-of-cell users, with unknown codes. In this paper we develop a number of group-blind multiuser detectors using a subspace approach. One class of detectors developed has a computationally efficient structure of a subspace estimation common to all known users, followed by a simple processing specific to each user. The performance of the detectors is compared to that of the purely blind detector and the non-blind detector, and the group-blind detectors are seen to have the best performance.