Research On Clock Synchronization Algorithm In Underwater Acoustic Communication Network

Because it is difficult to deploy underwater communication infrastructure similar to ground base stations,underwater acoustic communication network is a typical distributed system.Clock synchronization is the basis of node cooperation,sleep scheduling and slotbased channel access in distributed systems.The existing clock synchronization schemes in underwater acoustic communication networks are mainly centralized synchronization,which depends on the beacon nodes that can provide standard clock,and most of them require the synchronizing nodes to be within the one-hop transmission range of the beacon nodes,so it is difficult to deploy in practice and with low robustness.In addition,the rare distributed clock synchronization schemes which do not depend on beacon nodes in underwater acoustic communication networks can be divided into two categories:local synchronization and global synchronization.The purpose of distributed local synchronization is to obtain the relative speed relationship of clocks between nodes,but it can’t support upper applications such as sleep scheduling,data fusion based on timestamp,which require unified clock information of the whole network.However,the existing distributed global synchronization schemes have some disadvantages,such as relying on proprietary synchronization parameters,high requirements for network connectivity,and poor practicability.Therefore,the goal of this paper is to design distributed,efficient and global clock synchronization protocols for underwater acoustic communication networks.This paper found that the firefly heuristic synchronization algorithm can meet the distributed and global design goals through the arrangement and analysis of the existing synchronization technology,and its one-way broadcast information exchange mode has less control packet transmission requirements than the common two-way unicast form.In order to eliminate the adverse effects of non-negligible and unequal propagation delay between nodes on firefly-inspired synchronization algorithm in underwater acoustic communication,based on the dynamic delay compensation firefly synchronization algorithm,this paper designs the positive and negative coupling mechanism and creatively puts forward the dynamic waiting time setting method,and obtains the distributed global clock synchronization algorithm NDPS.In order to further reduce the energy consumption in the synchronization process,on the basis of NDPS algorithm,through in-depth analysis of the key factors affecting whether nodes need to transmit data packets,this paper creatively designs a synchronous message adaptive transmission mechanism,and obtains the E-NDPS algorithm with better energy consumption.In addition,in order to effectively evaluate the performance of the proposed algorithm,this paper proposes a simulation system UWSA-Sim based on DESRT open source framework for underwater clock synchronization algorithm simulation.Simulation results show that the synchronization algorithm proposed in this paper is superior to the existing clock synchronization technology in terms of synchronization accuracy,convergence speed and practicability.