A time varying transform domain excision filter for interference rejection in direct-sequence spread-spectrum

The performance of a direct-sequence spread-spectrum (DSSS) receiver with a transform domain prefilter is presented. The ability of a time-varying transform domain filter to reject narrowband interference is studied for different parameters as a function of noise power and jammer power. Digital processing design trade-off issues such as the transform domain excision filter bandwidth and window functions are explored. Extensive Monte Carlo simulations are performed to characterize system performance and parameter sensitivities. Receiver eye patterns are used to investigate the intersymbol interference (ISI) introduced by the time-varying interference rejection filter. Methods of reducing ISI are discussed. Hardware implementation issues are also considered