An evaluation of the potential of synchronized time to improve voice over IP quality

Delivering PSTN-Iike quality over current best-effort Internet infrastructure presents many technical challenges. Much research in recent years has focused on receiver-based approaches which adapt to varying network conditions in order to optimize playout quality. In this paper, we propose and evaluate a receiver-based approach that implements a hybrid adaptive-fixed playout regime by integrating synchronized time into the playout algorithm. Such an approach can deliver significantly better quality than existing adaptive techniques particularly when the underlying network is not heavily congested and end-to-end delays are not excessive. We present some initial results from our testbed system using the ITU-T E-model to quantify improvements.