Narrowband interference suppression in CDMA using random walk tracking algorithm

It has been shown that the narrowband interference suppression capability of a direct sequence spread spectrum system can be enhanced considerably by processing the received signal via a prediction error filter prior to correlating it with the pseudo noise (PN) sequence. In this paper we present a new method to suppress narrowband interference in direct sequence code division multiple access (DS-CDMA) systems. The proposed scheme is a nonlinear predictor that consists of a quantizer and random walk tracking algorithm. This algorithm is used for tracking a random walk in white Gaussian noise. This algorithm has two important features. First, this algorithm does not require the estimation of the interference statistics. Second, it does not require training sequences. Computer simulation results show that the proposed approach has better performance than conventional linear filtering.