HDL implementation of the variable step size N-LMS adaptive algorithm

This paper proposes a Verilog implementation of the normalized least mean square (NLMS) adaptive algorithm, having a variable step size. The envisaged application is the identification of an unknown system. First the convergence of derived LMS algorithms was analyzed in a Simulink application. The NLMS was chosen for its good convergence and stability. Next a HDL implementation was developed for a 4^th order NLMS adaptive filter. ModelSim simulations results altogether with plots obtained in Matlab prove the good behavior of the NLMS algorithm, making it an important competitor for the conventional LMS.