A fast null steering algorithm for linearly constrained adaptive arrays

A fast null steering algorithm for adaptive arrays with a look direction constraint is investigated. In this algorithm, the least mean square (LMS) algorithm is used to adaptively adjust the positions of the array response zeros one after another in a time-multiplexed manner to track unknown jammers. To ensure that the look direction response and the other zeros remain unchanged when a particular null is being updated, the element signals are suitably transformed before the LMS updating. Despite this signal transformation, the new algorithm has almost the same implementation complexity as when the LMS algorithm is employed directly, as only one zero is being adaptively updated at any instant. However, with each null being independently steered, the convergence behavior of the new algorithm is significantly faster and is almost independent of the external noise environment