A new efficient PNLMS based algorithm for adaptive line echo cancellation

Echo cancellers with long impulse responses are usually used in networks with long echoes. Since long adaptive filters with sparse target filters usually converge very slowly, adaptation algorithms with fast convergence rate are needed. PNLMS is one of the algorithms that is designed for fast convergence on sparse impulse responses. But there are some disadvantages to this algorithm. The computational complexity of this algorithm is prohibitive, especially for long echo tails. Another disadvantage is that its convergence rate slows down significantly after the adaptation of large taps. In this paper we propose new algorithms to solve both these problems. In another part of this paper, we present a modified PNLMS algorithm with better computational and convergence characteristics. Proposed algorithms show a better performance than PNLMS both in convergence rate and computational complexity.