Systems and methods for synchronization in asynchronous transport networks

Abstract

Techniques for synchronizing the clock of a local telecommunications network connected to a remote clock source through an asynchronous transport network such as an Ethernet metropolitan area transport network. A basic holdover loop for retaining the current reconstructed clock frequency signal receives weighted corrections from an open loop and a network time protocol filter loop. The open loop measures data packet interarrival times on the local network and calculates a first reconstructed clock frequency signal. The network time protocol loop applies network time protocol to generate timestamps over the asynchronous transport network which are used to generate a second reconstructed clock frequency signal. The first and second reconstructed clock frequency signals are combined using dynamically adjusted weight factors and compared with the current reconstructed clock frequency signal to correct the latter which then synchronizes the clock of the local telecommunications network.