The Robust Proportionate Affine Projection Algorithm for Network Echo Cancellation

Echo cancelers which cover longer impulse responses (>= 64 ms) are desirable. Long responses create a need for more rapidly converging algorithms in order to meet the specifications for network echo cancelers devised by ITU (International Telecommunication Union). In general, faster convergence implies a higher sensitivity to near-end disturbances, especially "double-talk." Recently, a fast converging algorithm called Proportionate NLMS (Normalized Least Mean Squares) algorithm (PNLMS) has been proposed. This algorithm exploits the sparseness of the echo path in order to increase the convergence rate. A robust version of PNLMS has also been presented which combines a double-talk detector with techniques from robust statistics to make the algorithm insensitive to double-talk. This paper presents a generalization of the robust PNLMS algorithm to a robust Proportionate Affine Projection Algorithm (APA) called PAPA. It converges very fast, and unlike PNLMS, is not as dependent on the assumption of a sparse echo path response.