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

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