Study On Key Technologies Of High Precision Clock Synchronization In Time Sensitive Network

With the rapid development of network technology,Ethernet has become the most widely used LAN communication standard.However,its non-synchronous working method makes the data transmission time difficult to be accurate.In order to increase the real-time capability and the reliability of Ethernet data transmission,TSN time-sensitive network has emerged.The TSN executes events with a deterministic scheduling mechanism,which depends on the support of a high-precision clock synchronization system.The IEEE 802.1AS protocol is a high-precision clock synchronization protocol standard in the TSN protocol stack.It provides precise timing and synchronization techniques in time-sensitive networks to ensure that all nodes in the network can work on the same time base.The IEEE 802.1AS_Rev protocol,as a revision,is dedicated to dealing with network failures while ensuring high-precision clock synchronization.As a new protocol standard,IEEE 802.1AS and its revision are still developing and improving.Focusing on the synchronization technology in time-sensitive networks,this paper analyzes the IEEE 802.1AS and IEEE 802.1AS_Rev protocols from the perspective of time synchronization accuracy and reliability.It researches the accuracy of clock synchronization and the implementation of the synchronization redundancy mechanism,and then proposes the improvement solutions.The main research contents are as follows:Firstly,this paper studies the principle of IEEE 802.1AS generalized precision time protocol and revised IEEE 802.1AS_Rev protocol,it explains the time-aware network and time-aware system structure in the protocol,and introduces the synchronization model as well as specific synchronization mechanism of time-aware system in detail.At the same time,this paper analyzes the "multi-domain" mechanism in the IEEE 802.1AS_Rev protocol and the redundancy levels it supports.Secondly,this paper studies the accuracy of time synchronization in IEEE 802.1AS protocol.It establishes the clock synchronization system model and studies the factors affecting the synchronization accuracy and the relationship between synchronization accuracy with the hop count of nodes in the network topology.It designs the simulation model of the synchronization system,and simulates the synchronization process by the NS3 simulation software.After theoretical analysis and simulation,this paper optimizes the synchronization accuracy and stability of nodes by Kalman filter based clock synchronization correction algorithm.Thirdly,this paper studies the reliability of time synchronization technology.Through the research and analysis of the "multi-domain" mechanism in the IEEE 802.1AS_Rev protocol,the specific path redundancy and grandmaster clock redundancy methods of the single-ring network are designed.The redundancy mechanism ensures that the synchronous network can quickly recover after the path is invalid or the grandmaster clock fails,improving the reliability of the system.In addition,this paper designs the simulation model of the synchronous redundancy mechanism,and the NS3 simulation software is used to simulate and verify the fault recovery capability of the synchronous network.Finally,this paper proposes a group-ring redundant network based on "multi-domain".Through simulation research and theoretical analysis,it is found that the redundancy mechanism of the single-loop network can help the network recover from the path or grandmaster clock failures.However,due to the limitation of the single-loop network,the redundancy method also has shortcomings.Therefore,based on the basic redundancy mechanism,this paper proposes a group-ring redundant network based on “multi-domain”,which reduces the number of hops in the network and increases the anti-destructive capability of the network through a group-ring topology to optimize the redundancy mechanism.