Research On MAC Mechanism And Time Synchronization For Underwater Gliders

In recent years,Underwater wireless acoustic sensor networks'(UWASNs)researches have changed to using underwater gliders because of the advantages of low energy consumption,long working time and long sailing distance.However,The movement of underwater gliders' position changes the propagation delay of packets.The reliability of communication decreases.Traditional underwater media access control(MAC)algorithm is oriented to static topology and is not suitable for dynamically changing networks.Therefore,it is necessary to design a data transmission algorithm for underwater glider networks.We propose the dynamic MAC mechanism and time synchronization algorithm for the underwater glider networks.The dynamic MAC mechanism of the underwater glider networks includes two parts: underwater glider position prediction and channel allocation.Aiming at the realization of this mechanism,Glider-MAC is designed.In addition,for the MAC transmission of underwater gliders affected possibly by time synchronization,we propose the intra-group time synchronization algorithm—G-Sync and inter-group time synchronization algorithm—time synchronization with multiple access data transmission algorithm(TSMP)based on the underwater glider team collaboration.G-Sync calculates skew to compensate the clock.TSMP uses a local time synchronization method without beacon nodes to synchronize nodes' clock.The Glider-MAC,G-Sync and TSMP are verified by simulation experiments.The simulation results show that the Glider-MAC can be used in the communication of the underwater glider networks.It can improve the delivery rate of data packets.Compared with P-MAC and R-MAC,the ratio is increased by 12% and 25%,respectively;G-Sync and TSMP have good performance in terms of synchronization accuracy.TSMP has higher energy efficiency than the separated time synchronization and multiple access approach.The research in this paper provides a certain theoretical basis and application value for realizing a good data transmission of the underwater glider networks.