Observation-based Clock Synchronization in Wireless Sensor Networks

In wireless sensor networks, each wireless sensor node records events occurred in its observation area with their observation time. Each wireless sensor node possesses its own local clock whose drift and offset are generally different from the others. By using observation records of the commonly observed events by neighbor wireless sensor nodes, this paper proposes a novel method to estimate the relative drift and offset between local clocks of the neighbor wireless sensor nodes. Here, each sensor node only detects the occurrences of events and cannot achieve the locations where the events occur. Hence, commonly observed events between neighbor wireless sensor nodes are required to be detected. Our proposed method applies a heuristic that multiple observation records in neighbor wireless sensor nodes whose intervals are the same are estimated to be commonly observed events. Keywords—wireless sensor networks; observation time; local clock synchronization; relative drift estimation; relative offset estimation