Jammer excision in spread spectrum communications via Wiener masking and frequency-frequency evolutionary transform

We propose jammer excision techniques for direct sequence spread spectrum communications when the jammers cannot be parametrically characterized. The representation of the non-stationary signals is done using the time-frequency and the frequency-frequency evolutionary transformations. One of the methods, based on the frequency-frequency representation of the received signal, uses a deterministic masking approach while the other, based on nonstationary Wiener filtering, reduces interference in a mean-square fashion. Both of these approaches use the fact that the spreading sequence is known at the transmitter and the receiver, and that, as such, its evolutionary representation can be used to estimate the sent bit. The difference in performance between these two approaches depends on the support rather than on the type of jammer being excised. The frequency-frequency masking approach works well when the jammer is narrowly concentrated in parts of the frequency-frequency plane, while the Wiener masking approach works well in situations when the jammer is spread over all frequencies. Simulations illustrating the performance of the two methods, in different situations, are shown.