Low-rank minimum variance CDMA receiver in multipath channels

The minimum variance receiver has been previously proposed to suppress the multiple-access interference (MAI) blindly in CDMA channels by minimizing the receiver´s output variance based on constrained optimization. In this paper, we propose a low-complexity minimum variance receiver that achieves almost the same performance as the high-complexity one with the optimal constraint vector. The proposed receiver is a RAKE receiver followed by an equal gain combiner. The impulse response of the filter in each finger is obtained by the minimum variance criterion. The low-rank minimum variance receiver uses a reduced-rank approximation of the estimated data covariance matrix. Its performance is better than the full-rank version of the receiver. The receiver is implemented adaptively with the same structure as a generalized sidelobe canceler