Research on Clock Synchronization Mechanism in Wireless Sensor Networks

The paper presented a cluster-based clock synchronization mechanism for wireless sensor networks (CBCS). The mechanism works in two phases: horizontal clock synchronization phase and vertical clock synchronization phase. In the horizontal synchronization phase, it adopts traditional pair-wise packet exchange mechanism to finish the clock synchronization between the base station and cluster heads through establishing a hierarchical topology structure. In the vertical synchronization phase, it adopts pair-wise packet exchange and unidirectional reference broadcast mechanism to finish the time synchronization between cluster heads and cluster members. Moreover, it used linear least square to estimate the clock offset of nodes which achieved a good precision. Finally, the local clocks of all nodes in the network can synchronize to each other. The results of which simulated on NS-2 show that CBCS has a good precision and low message cost.