Mac-Time-Stamping-based High-accuracy Time Synchronization for Wireless Sensor Networks

Abstract

Time synchronization is essential for applications in Wireless Sensor Networks (WSNs). The accuracy and energy consumption are main factors to evaluate a time synchronization protocol. Pairwise Broadcast clock Synchronization (PBS) was proposed to greatly reduce energy consumption, especially in densely connected network. In PBS, some nodes only need to listen the overhead messages instead of broadcasting any messages. In this paper, we present a Mac-Time-Stamping-based High-accuracy Time Synchronization with 2 points Least Squares for Wireless Sensor Networks called PBS-2LS. It does not increase the number of broadcast messages compared with the original PBS, but changes the format of messages. The method of two points least squares is used to calculate the clock drift and offset. The timestamp of Mac layer is applied in our approach. Thus, the accuracy of our approach becomes higher than PBS and the energy consumption is similar to PBS. We use network tools NS-2 to evaluate our approach and compare it with PBS and TPSN, which are two existing time synchronization protocols. The simulation results show that accuracy and compensating clock drift are better than PBS and TPSN.