Integration of a jitter control module into a packet voice application
Wing Yee Winnie Lee · Summit (Simon Fraser University) · 2003
In a packet voice application, source speech is coded and packetized and is sent through the network to the receiver, where the packet is decoded.The transfer of speech packets through a packet network introduces a variable transport delay.Packets may be lost and they may take different paths resulting in packets that arrive out of order.This arrival time variance (or jitter), packet loss, reordering and duplicating, must be handled properly to avoid gaps of degradation in the re-constructed speech.A jitter control module is required to cope with the asynchronous arrival of packets from the network.A jitter control module is a key component of the speech service of a packet voice application.The packet received from the network will be held within a storage location referred to as the jitter buffer.The jitter control module is responsible for managing the release time of the packets stored within the jitter buffer to the speech decoder, where the speech will be reconstructed.The jitter buffer also works closely with the packet loss concealment algorithm (PLC) and the comfort noise generator (CNG) to ensure that the reconstructed speech is of the highest quality, while minimizing the end-to-end delay. This document reports my work on the project-Integration of a jitter control module into the LDX at Broadcom Canada LTD.The project involves the integration of a jitter control algorithm into a Voice over Internet Protocol (VoIP) application with low channel density developed by Broadcom Canada called Low Density Xchange (LDX).The algorithm was originally developed for another Broadcom packet voice gateway solution with high channel density.The jitter control module was found to be vital for the quality of the reconstructed speech from LDX when operating over a jittery network.Data memory requirements have been optimized to ensure that the resource requirements of the jitter control module are acceptable on the target platform. Jitter Control Algorithm 144.