With the presently described echo canceller, a sparse adaptive transversal filter is used to model and cancel only the active regions of the echo impulse response. Since the tap coefficients, in the dormant regions, are set to zero and have no random fluctuation this approach reduces computation time and excess meansquare error in the tap coefficients. Also, the present design provides for increased speed of convergence of the sparse canceller as compared to the full-tap canceller, since convergence is proportional to the number of active taps in the LMS algorithm.
Adaptive sparse echo canceller using a sub-rate filter for active tap selection