A Cooperative Time Synchronization Protocol for Wireless Sensor Networks

Abstract

The synchronous precision of synchronization protocol is low and the scalability is limited strictly in large scale wireless sensor networks (WSNs).Considering the issue, a novel cooperative time synchronization protocol based on pulse-coupled oscillators and distributed diffusion (CTSP) is proposed in this paper. The protocol works in two phases：clock tick synchronization phase and time synchronization phase．In the clock tick synchronization phase, the phases of the pulse-coupled oscillators is changed by the pulse coupled signal of the SINK node. The tick synchronization of all nodes is achieved by distributed diffusion. In time synchronization phase, the average time of reference nodes is spread to a limited number of hops based on two-way message exchange mechanism. Moreover, in order to achieve the synchronization of entire network, it adopts the method of mutual diffusion to finish the approximately synchronization between the node time and the average time of all nodes. By comparing CTSP with TPSN, we show that, CTSP can synchronize the network quickly with good precision convergence speed and scalability, which appropriates for large-scale WSNs.