Performance of Arbitrary Interference Rejection Based on Decision Feedback Filers in DSSS Systems

The aim of this paper is to establish upper bounds of SNR improvement factors for the maximum attainable performance of a system when the interference has an arbitrary spectral density using any realizable decision feedback filter. In contrast to conventional results for a first-order autoregressive interference based on decision feedback filters, we allow the jammer to have an arbitrary rational spectral density. The quality of the approximation of upper bounds is also investigated, which is exponentially tight. The significance of the analysis result is that the expression for upper bound is simple, closed-form, and valid for arbitrary jammer ´s spectral densities.