A fast robust quasi-newton algorithm for adaptive arrays

This paper outlines the development of a new type of digital adaptive-array algorithm for interference cancellation. It is fast in the sense that it requires only order-of-N computations per iteration and converges in a substantially fixed number of iterations (proportional to N) regardless of the signal scenario or geometry of the N-element array. The need for such algorithms arises in dynamic signal scenarios requiring spatial cancellation of co-channel interference, such as in military aircraft communications [1] and digital mobile-radio telephony [2, 3]. Existing order-of-N LMS (Least Mean Squares) algorithms are inadequate for such applications as they suffer from very slow modes of convergence. Ordinary RLS (Recursive Least Squares) algorithms converge much faster but require order-of-N operations per iteration which hampers their realization.