Weight-controlled nonlinear successive interference cancellation methode for DS-CDMA systems

Optimal multiuser detection is a 0-1 quadratic optimization problem with binary constraints that demands the search of the whole signal space to achieve the optimal solution. In the presence of such hardship, some soft interference schemes based on Gaussian-Seidel and Jacobi algorithms have been developed to achieve sub-optimum solution of the original problem. This paper presents a novel constrained successive overrelaxation algorithm for the original optimum multiuser detection problem, which corresponds to a near-optimum weight-controlled nonlinear parallel interference cancellation scheme for the DS-CDMA systems. The proposed scheme converges much faster than the Gaussian-Seidel method and Jacobi method without significantly increasing the complexity. The proposed method can achieve better performance than the conventional linear minimum mean squared error mulituser detection method within a few iterations.