Hybrid fractional tap-length LMS algorithm for high noise environment

In the high noise environment, the steady-state tap-length of the fractional tap-length LMS algorithm often suffers from unexpected change caused by the high noise, which tends to degrade the performance of the adaptive filter. The amplitude-limiting idea is introduced to limit the instantaneous value of the cost function. This helps to reduce the fluctuation of the steady-state tap-length. However, the convergence rate of tap-length tends to become slow. In order to achieve both good steady-state tap-length performance and relatively fast convergence rate, a hybrid fractional tap-length algorithm is proposed in this paper. In the hybrid algorithm, the fractional tap-length LMS algorithm and amplitude-limiting one are mixed by a single mixing factor. The efficiency of the hybrid algorithm is verified by simulation.