Adaptive Source Time Synchronization for Low-Duty-Cycle Wireless Sensor Networks

Time synchronization is critical for most distributed systems, especially for low-duty-cycle Wireless Sensor Networks(WSNs). Low-duty-cycle WSNs make use of time synchronization in many contexts(scheduling and sleeping, TDMA, Event Identification, data fusion, etc). A novel adaptive source time synchronization algorithm designed for low-duty-cycle WSNs, namely ASTS, is presented in the paper. The algorithm can be used for a small Low-Duty-Cycle WSN to be synchronized to a common clock, or used for a giant Low-Duty-Cycle WSN to be synchronized distributed. To improve the synchronization accuracy, all nodes estimate their time drifts relative to their neighbors using Maximum Likelihood Estimation, and get be synchronized to a common clock or their heads based on a vector of time drifts carried by the reference packet sent by the reference node. Simulation shows that the algorithm drastically improves the synchronization accuracy and scalability, and is much more applicable for low-duty-cycle WSNs than other synchronization algorithms.