Adaptive packet selection for clock recovery

Abstract

Packet delay variation (PDV) is a dominant source of noise in packet-based synchronization systems. To filter this type of noise, many clock recovery algorithms select packets based on the sample-minimum statistic of the network transit time. Although such a filter can be very effective in certain types of networks, there are just as many networks and background traffic patterns for which sample-minimum is far from optimal. In this paper, we propose a filter that dynamically evaluates multiple packet selection criteria and selects the one that currently minimizes the noise. We also present the results of an experimental evaluation of the new adaptive filter.