A Fault Tolerant Time Synchronization Protocol for Underwater Acoustic Networks

Time synchronization is a supporting technology and necessary precondition for underwater acoustic (UWA) networks. Sensation and actuation in UWA networks need coordination across nodes. Under normal circumstances, the deployment of UWA networks is large, and the energy resources are limited. The existing protocols can't achieve an accuracy high enough and consume overmuch energy, so they could not well adapt to UWA networks yet. Although many protocols are dedicated to improving accuracy, they often work on the perspective of ameliorating the exchanged mechanism of information and ignore the propagation delay with the greatest impact on accuracy that affected by channel quality. In this paper, we propose a fault tolerant time synchronization protocol. It dedicated to enhancing accuracy by improving the processing method of exchanged synchronization messages and enables the synchronization process adapt to unstable channel quality. The simulation results show that the protocol achieves a high accuracy with low energy cost, and as channel quality deteriorates, compared with existing protocols, its accuracy declines flatter and fluctuates in a smaller range.