Adaptive Filters for Suppressing Irregular Hostile Jamming in Direct Sequence Spread-Spectrum System

The purpose of this paper is to design a stable and high-performance adaptive filter for suppressing irregular hostile jamming in direct sequence(DS) spread-spectrum systems. A gradient-search fast converging algorithm is suggested(for convenience, named GFC). And for the case of a sudden parameter jump or incoming of an interference, the transient behaviors of the receiver using an GFC adaptive filter are investigated and compared with those of the receiver using an LMS or a Lattice adaptive filter. Then the results are shown in the response graphs of the simulated receiver during the short period when the characteristic of a jammer is suddenly changed. Steady state performances of those receivers are also evaluated in the sense of the excess mean square error over that of an optimum receiver for suppressing stationary interferences. Since the suggested algorithm performs better than LMS or Lattice algorithm, this algorithm is principlly applicable to designing an appropriate adaptive filter for suppressing irregular hostile jamming in DS spread spectrum system.