Research On Time Synchronization Method For Time-sensitive Networking

With the rapid development of industrial technology,the monitoring of information gathering and automatic control based on real-time industrial scenes are progressively emerging.A large amount of audio,video and real-time control data needs to be transmitted over Industrial Ethernet,putting higher demands on traditional networks.To meet the integration of IT & OT,as well as real-time and deterministic requirements of industrial Ethernet,the IEEE has introduced Time-sensitive Networking based on standard Ethernet queue programming.To provide a unified high-precision time reference for Time-sensitive Networking,the IEEE TSN working group has developed the IEEE 802.1AS time synchronization protocol.The protocol synchronizes each node in the network to the only grandmaster selected by competition,thereby ensuring clock synchronization and low latency for data transmission and node applications in time-sensitive networks.The main research focus of the IEEE 802.1AS protocol is to improve the accuracy and precision of clock synchronization,to improve the reliability of clock synchronization,and to better adapt to the dynamic network of TSN.This thesis has conducted a deep study on the IEEE 802.1AS clock synchronization protocol,and has a detailed learning on the time-aware network and time-aware system architecture defined in the protocol,and has a comprehensive analyzing on the best master clock algorithm,propagation delay measurement and transport of time-synchronization information used in the protocol.By addressing gaps in the original protocol mechanism,a variety of optimization design methods for the clock synchronization algorithm are proposed.By adding a new port role,discarded messages are used to form dual synchronization paths on the nodes to improve the accuracy and robustness of synchronization.By adding the port's message trigger mechanism,it can detect new nodes in the network in time and improve the dynamic performance of synchronization.By increasing the timestamp of a specific message,it can compensate for the unrecorded two-steps delay during the time synchronization process,and improve the accuracy of synchronization.After that,a modular time-aware system model has been built by using OMNe T++ network simulation software,and some simulations with different conditions has been done to test the time synchronization mechanism and to verify the effectiveness of the optimized algorithms.The simulation results show that the designed time-aware system can achieve the full time synchronization mechanism defined by the IEEE 802.1AS protocol.Compared to the original protocol,the optimized algorithms proposed in this thesis can effectively improve the percision,accuracy and robustness of time synchronization,and have good compatibility for complex hybrid and dynamic networks.