Removing Long Echo Delay Using Combination of Jitter Buffer and Adaptive Filter

Echo in telephone transmission systems is a serious problem. It affects and distorts the desired speech. Echo cancellation methods have studied for a few decades and standardized in ITU G.168. The core theory in echo cancellation methods is using an adaptive filter which uses one of these algorithms: LMS (least mean square), NLMS (normalized least mean square), RLS (Recursive least squares), etc to remove the echo. In fixed conditions, these algorithms are efficient to remove echo. However, in some real telecom environments, with long echo delays, we must increase the filter length to a big value. But, it's not efficient in performance due to high computational complexity. In this paper, we propose a solution that uses ajitter buffer along with an adaptive filter to compensate long echo delays. This solution demonstrated its efficiency in Viettel Network-the biggest telecom provider in Vietnam-both on voice quality and system performance.