Research On Time Synchronization Algorithm In Underwater Acoustic Sensor Network

The main content of this dissertation is that the time synchronization algorithms inunderwater acoustic sensor network. By studying the existing algorithms, it is found that theresult of the existing algorithms cannot effectively eliminate the effect of the node movement,propagation delay and sound velocity error on the accuracy of the algorithms. The Dopplertechnology and the relationship between the nodes relative movement.etc used in existingalgorithms to reduce the bad effect of node movement, which only solves the problem by thespeed of relative movement, cannot effectively eliminate the effect of node movement on theaccuracy of the time synchronization. And the suitable sound velocity model is not adopted inthe existing algorithms, if the accuracy can be improved and the error is decreased, thesuitable sound velocity model must be adopted.To reduce the impact of node movement, propagation delay and the measurement of thesound velocity on time synchronization, in this paper the grading time synchronizationalgorithm based on the single beacon node is first proposed. The suitable sound velocitymodel, ocean current model, the time difference of send time and the time difference ofreception time are used in this algorithm to calculate the clock skew and clock offset from thelinear regression, in order to improve the accuracy of the algorithm. Although the accuracy isimproved, the impact of the beacon on ordinary node is unidirectional. So the unidirectionaltime synchronization algorithm based on the multi-beacon nodes is proposed. The soundvelocity model and ocean current model are also used in this algorithm, the relationshipbetween the distance of the signal transmission and the distance between the beacon node andordinary node is analyzed, the clock skew and clock offset are calculated in the algorithm. Atlast, the multi-beacon nodes time synchronization based on the long baseline is put forward.The sound velocity model and the theory of the long baseline are adopted in the long baselinesystem to calculate clock skew and clock offset.Compared with the existing synchronization algorithms, the synchronization accuracy ofthe three algorithms proposed in this dissertation is improved. The error of clock skew andclock offset in the grading time synchronization algorithm based on the single beacon node is smaller than those in MU-Sync. The accuracy of the unidirectional time synchronizationalgorithm based on the multi-beacon nodes is higher than that in Mobi-Sync and the gradingtime synchronization algorithm based on the single beacon node, for the clock skew and clockoffset impact one ordinary node multidirectionally. The multi-beacon nodes timesynchronization based on the long baseline is a specific application of time synchronizationtechnology. Compared with the grading time synchronization algorithm based on the singlebeacon node, the accuracy of the multi-beacon nodes time synchronization based on the longbaseline is higher. So the specific time synchronization algorithm chosen depends on thespecific scene.