Time Synchronization in Wireless Sensor Networks: a Review

Time synchronization for wireless sensor networks (WSNs) has been studied in recent years as a significant research issue. Many applications based on WSNs assume local clocks at each sensor node need to be synchronized to a common time scale. It is particularly important for many of the tasks such as synchronizing event detection, data fusion, and coordinating wake and sleep cycle. Time synchronization requires accurate time stamping of events and coordination between the sensor nodes to reduce power consumption. Time synchronization protocols provide a mechanism to synchronize the local clocks of the nodes in the network to a global clock or relative to each other. During the last decade, many researchers have investigated the time synchronization in WSN, and proposed numerous time synchronization protocols. This paper reviews various existing protocols based on factors such as accuracy, efficiency, and complexity. The studied Synchronization protocols include conventional time sync protocols (RBS, TPSN, FTSP) and many other protocols aiming at providing common notion of time.