An optimized transmitter precoding scheme for synchronous DS-CDMA

This article presents a technique to reduce multiple access interference in the forward-link of a conventional DS-CDMA system by applying an energy constrained transformation to the transmitter output. For each symbol period, a new transformation is selected which minimizes the mean-squared error at the output of a bank of matched-filter detectors. This selection is subject to a constraint on total transmitted energy. It is shown that the proposed method results in substantial advantages over earlier similar techniques. The proposed algorithm can be implemented efficiently at the transmitter with existing optimization techniques that solve the quadratic trust-region subproblem.