Blind adaptive beamforming for CDMA based PCS/cellular

Abstract

A blind adoptive beamforming scheme is developed for CDMA that cancels strong multi-user access interference and optimally combines multipath based on the following observation: after passing the output of each antenna through a matched filter corresponding to the PN sequence of the desired user, one can isolate periods of time when the cochannel interference dominates. This allows one to estimate the spatio-frequency correlation matrix of the co-channel interference alone. The weight vector yielding the optimum signal to interference plus noise ratio for bit decisions is the "largest" generalised eigenvector of the signal plus interference spatio-frequency correlation matrix in the metric of the spatio frequency correlation matrix of the co-channel interference alone. Simulations are presented demonstrating the efficacy of the procedure.