Reliable Time Synchronization Protocol for Wireless Sensor Networks

Sensor network applications need synchronized time to the highest degree such as object tracking, consistent state updates, duplicate detection, and temporal order delivery. In addition to these domain-specific requirements, sensor network applications often rely on synchronization as typical distributed system do: for secure cryptographic schemes, coordination of future action, ordering logged events during system debugging, and so forth. This paper proposes a Reliable Time Synchronization Protocol (RTSP) for wireless sensor networks. In the proposed method, synchronization error is decreased by creating hierarchical tree with lower depth and reliability is improved by maintaining and updating information of candidate parent nodes. The RTSP reduces recovery time and communication overheads comparing to TPSN (Timing-sync Protocol for Sensor Networks) when there are topology changes owing to moving of nodes, running out of energy and physical crashes. Simulation results show that RTSP has about 10% better performance than TPSN in synchronization accuracy and the number of message in the RTSP is 10%~35% lower than that in the TPSN when nodes are failed in the network. In case of different transmission range of nodes, the communication overhead in the RTSP is reduced up to 50% than that in the TPSN at the maximum.