Adaptive IIR constrained LMS algorithm for multiple narrowband interference rejection

One of the common problems in digital signal processing is the filtering of signals in the presence of a narrow-band interference. Adaptive IIR digital multiple hand-rejection filters use pole-zero placement on the unit circle method, which is designed by a unique second-order filter structure. With unconstrained LMS algorithm, zeroes may converge to their optimum positions in certain cases, where the poles do not converge without a forcing condition. In this paper, a new design of adaptive digital band-rejection filter, constrained least-mean-squares (CLMS), is applied by adapting both poles and zeroes for the elimination of a narrow-band white Gaussian noise.