A blind multiuser receiver for the CDMA downlink

We propose a new blind space-time linear multiuser receiver for the CDMA downlink. The structure in the multiple access interference (MAI) for the downlink makes it possible for a receiver to suppress it without first obtaining the matched filter outputs for all the users (which comprise the sufficient statistics for optimum detection of the transmitted symbols); a 2D-RAKE receiver with appropriately chosen taps can suppress MAI reasonably well. Knowledge of all the users' codes is assumed and the taps of the 2D-RAKE receiver are estimated by making use of the subspace structure in the transmitted signal. Our approach does not require training symbols or channel estimation in order to estimate the receiver taps.