Research Of Time Synchronization Based On Bimodal Clock Frequency Estimation For Wireless Sensor Networks

To solve the problem of slow convergence using Sage-Husa method to estimate clock frequency on time synchronization in wireless sensor networks, a bimodal clock frequency estimation algorithm is proposed. The algorithm uses a threshold to determine which mode the clock frequency is in. For the jump mode, the ratio-based method is adopted to quickly track the clock frequency. While for the stable mode, the Sage-Husa method is used to improve the estimation accuracy. In order to verify the actual effect of the proposed algorithm, the modified least square method, ratio-based method and unscented Kalman filter are implemented to estimate the clock frequency in the level-based wireless sensor network, which can objectively indicate the validity of the proposed algorithm. Experimental results simulated on NS2show that the proposed algorithm has better performance both on estimation precision and convergent speed comparing with the methods aforementioned.