An Efficient Time Synchronization Protocol for Underwater Acoustic Networks with Capability of Prediction

Time synchronization protocol plays an important role in underwater acoustic (UWA) networks. Nodes need to be coordinated to work as a whole and achieve their functions as sensation and actuation. Many existing time synchronization protocols for UWA networks have been developed to achieve this goal. However, existing protocols can't meet needs of UWA networks in accuracy and energy cost. In this paper, we propose an efficient time synchronization protocol (EF-Sync) for UWA networks. It can fully utilize exchanged messages to make a bidirectional error estimation of clock skew error. And meanwhile, with the help of prediction by using the exponential smoothing algorithm which can be adjusted according to the channel quality, EF-Sync can compensate the clock offset with high accuracy. The simulation results show that it achieves a remarkable higher accuracy with low energy cost.