Cisco Systems Inc.

Legerity, Inc.

Herbert M K Chen

Fuling Liu

The present invention relates to a system and method for canceling echoes from telecommunications networks by providing a multi-adaptation echo canceller. Unlike conventional TDM echo cancellers, the present invention uses at least two echo cancellers arranged in a novel manner to cancel echoes generated by a voice packet associated with an IP network or the like. The present invention further provides a double adaptation echo canceller that transfers coefficients from a first echo canceller to a second echo canceller. The present system compares the single and double adaptation echo error signals and selects the echo canceller with the smaller error signal. This process is continuously repeated so that the system can select the optimal echo canceller for canceling echoes for each voice block/packet. The present invention can be implemented with any number of echo cancellers so long as the each block or packet can be processed within a specified time frame.

Multi-adaptation for a voice packet based

An automatic balance system for a transmit signal of a wireless local loop communication system. The automatic balance system includes a finite impulse response (FIR) filter system, the FIR filter system including at least one FIR tap for replicating at least one portion of an echo signal, the echo signal being an undesired component of the transmit signal. The system also includes a non-adaptive infinite impulse response (IIR) filter system operatively coupled to the FIR filter system, the non-adaptive IIR filter system including an IIR tap for replicating a long-tail portion of the echo signal. A first summer is operatively coupled to the FIR filter system and non-adaptive IIR filter system, the first summer combining the output replicated portions of the echo signal from the FIR filter system and the IIR filter system to generate a replicated echo signal. A second summer combines an inverted replicated echo signal with the transmit signal so as to substantially negate the echo signal from the transmit signal.

Growing community of inventors

Saratoga, CA, United States of America

Herbert M K Chen