A new narrowband interference suppression scheme for spread-spectrum CDMA communications

This paper presents a new nonlinear approach for narrowband interference (N BI) suppression in code-division multiple-access (CDMA) systems. The propos ed scheme is an adaptive nonlinear predictor that consists of an (N+1)-leve l quantizer four adders, and two adaptive linear filters, where N is the nu mber of users in the CDMA system. Both adaptive filters have the same coeff icients at each iteration: one for feedforward estimation of NBI and the ot her for feedback compensation for the estimated result. It could be regarde d as an improved version of the nonlinear predictor with offset outputs pre sented recently by Wang et at. Computer simulation results support that the improved offset predictor performs much better than the original one under the same complexity. As compared with the nearly optimal approximate condi tional mean filter, it achieves almost the same performance even at very lo w signal-to-noise ratio but involves much less complexity.