Global clock synchronization in sensor networks

Global synchronization is crucial to many sensor network applications that require precise mapping of the collected sensor data with the time of the events, for example in tracking and surveillance. It also plays an important role in energy conservation in MAC layer protocols. This paper discusses three methods to achieve global synchronization in a sensor network: a node-based approach, a hierarchical cluster-based method, and a fully localized diffusion-based method. We also give the synchronous and asynchronous implementations of the diffusion-based protocols.