Narrow-band jammer suppression using an adaptive lattice filter

It is well known that least-mean-squared (LMS) adaptive filtering can be used to suppress narrow-band jammers in a direct sequence spread spectrum receiver. To date, much of the work in this area has concentrated on the use of transversal adaptive filter structures. This paper demonstrates the performance of an adaptive lattice filter in this application. The reflection coefficients of the filter are adjusted using a gradient descent algorithm in an effort to minimize the mean-squared error and, in the process, suppress narrow-band interference. Experimental bit-error-rate performance curves are presented for 7- and 31- chip spreading sequences with a single tone jammer.