DAC-Sync: Research on underwater time synchronization algorithm based on Doppler effect and clustering model

Time synchronization technology plays an important role in underwater acoustic sensor networks, which is the foundation of the cooperation among network nodes to complete distributed tasks. To address the problem of long underwater propagation delay, the mobility of nodes, and the limited energy of nodes, this paper proposes an underwater time synchronization algorithm (DAC-Sync) based on the Doppler effect and the cluster model. The clustering model is used to realize the time synchronization between nodes in stages. Besides, the effect of clock frequency skew is considered when estimating the Doppler scale factor, the clock frequency skew is solved by multiple one-way interactions and obtain clock phase offset through a two-way interaction, to complete the whole time synchronization process. The performance of DAC-Sync was compared with CD-Sync under the same simulation conditions. The results show that, for punctuality accuracy, the algorithm drifts by an average of around 36 microseconds per second over a period of 106 seconds, while CD-Sync drifts by an average of around 146 microseconds per second, while, drifting 1.5 milliseconds and 6.1 milliseconds respectively for timing accuracy. For energy consumption, compared with CD-Sync, DAC-Sync has lower computing cost and simpler synchronization process. Therefore, this algorithm has higher energy efficiency and high synchronization accuracy.