A KALMAN FILTER-BASED ARCHITECTURE FOR INTERFERENCE EXCISION

This paper presents a novel Kalman filtering approach to the suppressi on of narrowband interference from direct sequence spread spectrum com munications systems. The approach is based on the digital phase-locked loop Kalman filter. Because the interference is assumed to be much st ronger than either the signal or noise, the Kalman filter locks onto a function related to the interference. The net result is an estimate o f the phase of the interference and its envelope. Though more optimum for interferer's of constant envelope, the algorithm is characterized as a function of the Kalman filter parameters through computer simulat ion for narrowband Gaussian noise interference. Examples of the phase- and envelope-tracking capabilities of the algorithm are presented, fo llowed by bit error rate curves for interference bandwidths ranging fr om 0.5% to 5.0% of the chip rate of the spread spectrum signal.