Performance bounds for linear blind and group-blind multiuser detectors

In blind multiuser detection for CDMA systems, the receiver knows only the code of the user of interest, while in group-blind multiuser detection the receiver knows a subset of codes, e.g., the in-cell users in a basestation. This paper derives bounds for the performance of linear blind and group-blind multiuser detectors. The bounds are derived under a number of different system assumptions. The bounds show the theoretical gain by using groupblind detectors over blind detectors, and they also show that previously developed blind and group-blind detectors are relatively close to optimum among estimators using only second order moments. However, the bounds also show that a considerable gap exist to optimum detectors that are not restricted to second order moments.