Probabilistic anonymous clock synchronization method and apparatus for synchronizing a local time scale with a reference time scale

摘要

A method is provided for synchronizing local times, maintained at nodes within a network architecture, with a reference time. A node according to the invention can synchronize its local time with the reference time source either actively or in a passive, or eavesdropping, manner. Which of the two manners is to be used preferably depends on whether the node's error exceeds a threshold, and whether the node receives an unsolicited burst of synchronization messages. The active manner is preferably a handshaking scheme, such as probabilistic clock synchronization, in which synchronization is initiated by a request from a node requiring synchronization, and a handshaking exchange of messages between the node and the reference time source establishes a temporal relationship, from which the node produces a synchronized time and a maximum error. The passive manner is preferably a manner in which the reference time source broadcasts a burst of reference-time-stamped synchronization messages, and the node eavesdrops on the messages. The receiving node establishes temporal relationships between certain ones of the local and reference time stamps. Using the temporal relationships, the receiving node updates its local time and its maximum error.