Tone interference suppression in DS spread spectrum systems by estimation of the conditional mean

In this paper a new method for tone interference suppression in direct sequence spread spectrum (DSSS) receivers is presented. The proposed interference suppression algorithm falls into the class of nonlinear adaptive prediction filters and is based on the estimation of the conditional mean of the jamming signal samples, conditioned upon the adjacent samples of the total received signal. The conditional mean is estimated in an iterative manner, as an average of sample triplets that fall in the vicinity of the point of interest. Since the estimate of the conditional mean function converges to the exact value in the mean-square sense as the number of the algorithm iterations tends to infinity, the algorithm performance improves with the number of iterations. Performance of a filter utilizing the new interference suppression method are compared with those of a transversal filter of the same complexity and illustrated through bit error rate and signal to jamming and Gaussian noise power ratio improvement curves