Blind multiuser detection based on linear constrained MMSE

Based on the minimum mean-square error (MMSE) criterion, a new blind multiuser detector is proposed. The searching space for the optimal detector is constrained according to the spreading code and channel properties of the desired user. The proposed constraint technique can guarantee that the optimal detector associated with the desired user locates in the searching space, whereas the existing methods consider only the spreading code and, consequently, cannot guarantee that the target optimal detector locates in the constrained searching space. Theoretical analysis and numerical results are presented.