Adaptive Echo Cancellation for Packet-Based Networks

Echo cancellation is essential if the transmission of voice data is to be of an acceptable quality over networks which introduce a significant end-to-end delay. A significant echo cancellation problem for this type of network is due to the fact that the delay is variable. This means that the canceller needs to track the delay and to reconverge for each change quickly enough to maintain efficiency in its control of the echo. This paper describes a system for dealing with abrupt changes in the network impulse response. The proposed model consists of an arrangement of echo cancellers, each referring to a particular delay, with the most appropriate canceller coefficients being chosen throughout the simulation as the system converges to the changing delay.