A reduced complexity least squares algorithm for look direction constrained broadband arrays with maximally flat response zeros

This paper presents and investigates a new algorithm for look direction constrained broadband arrays based on using recursive least squares in the spatial domain and maintaining maximally flat responses at nulling positions in the frequency domain. The main advantage of the algorithm is that the number of adaptive weights is effectively reduced by a factor of L, where L is the number of tap weights per spatial degree of freedom. As a result, the implementation complexity is reduced by O(L²), while the convergence or tracking behavior is improved by O(L), when compared with using conventional least squares techniques directly