Adaptive RLS filters with linear and quadratic constraints

In many adaptive signal processing applications, it is often desired to impose linear and quadratic constraints on the adaptive filter weights in order to meet certain performance criteria. The paper presents a modification of the well-known adaptive RLS or FLS algorithm to achieve this. By way of illustration, the paper considers an adaptive narrowband beamformer with first and second order spatial derivative constraints. The performance of the algorithm is studied via computer simulations