An accurate closed-form formula to calculate the dejittering delay in packetised voice transport

Abstract

The transport of voice over a packet-based network introduces jitter in the voice flow. The jitter is compensated in the dejittering buffer by artificially delaying the first packet of the flow over the so-called dejittering delay and then cyclically reading the packets from the dejittering buffer. In this paper, we first give a general numerical method to compute the dejittering delay. Then, we introduce and justify a closed-form heuristic formula to calculate the dejittering delay for a network consisting of identically loaded, independent nodes modelled as M/G/1 queues. We demonstrate the accuracy of the heuristic formula by means of some numerical examples. Since the heuristic formula is closed-form, accurate, and explicitly shows the influence of certain network parameters, it is the preferred method to dimension the dejittering buffer and to perform sensitivity studies.