Cognitive Adaptive Array Processing (Caap) - Adaptivity Made Easy

Abstract

Cognitive Adaptive Array Processing (CAAP) is adaptive array jammer cancellation which makes use of information gathered about the jammer. With CAAP the jammer cancellation can be done with dramatically less processing, with orders of magnitude fewer training samples and with less degradation of the antenna sidelobes. With digital beam forming (DBF) now being more widely used CAAP becomes more feasible to implement. Its time has come. It should be looked at. The results are presented in tutorial form without heavy math. Instead physical explanations are given for these results. The CAAP technique makes use of the information available as to where the jammers are rather than assuming their location is not known as done for the classical sample matrix inversion (SMI) method. This is reminiscent of the Knowledge Aided-STAP (KA-STAP) technique used by DARPA. In many cases no interference covariance matrix inversion is needed and when needed the matrix size is reduced by orders of magnitude and in turn the computation of its matrix inverse. This method reduces the 10 to 30 dB antenna sidelobe degradation usually resulting from using the SMI method. The advantages re the use of diagonal loading (DL) and the principal component (PC) techniques are also addressed. The CAAP technique lends itself well to conventional and MIMO array systems when digital beam forming is used which is the future trend.