SUPPRESSION OF NARROW-BAND INTERFERENCE IN A DIRECT SEQUENCE SPREAD SPECTRUM RECEIVER IN THE ABSENCE OF CARRIER SYNCHRONIZATION.

Experimental and analytical results have shown that least-mean-squared (LMS) adaptive filtering improves the performance of direct-sequence spread-spectrum receivers in the presence of narrow-band jammers. Since the adaptive jammer suppression is, at times, peformed at baseband, previous investigations have assumed that both carrier and chip synchronization have been achieved prior to the suppression of the jammer. However, the presence of the jammer can hinder the acquisition and the maintenance of this synchronization. The author discusses an LMS-based jammer suppression structure which does not require carrier synchronization. Monte Carlo simulation results are presented which show bit-error-rate (BER) performance for a receiver equipped with such a jammer suppressor.