Research And Implementation Of High-precision Network Time Synchronization

With the development of 5G system,it is necessary to predict the future communication scenario reasonably.China's imt-2020 5G clearly points out that China's future communication scenario demand is 3H:high conversion,high density and high speed.The technical basis of requirement realization is that each node can achieve time synchronization at nanosecond level.The main work of this paper is the research and implementation of high-precision network time synchronization.Adopting the hardware design of the master-slave board,selecting the Gigabit network card,the main board runs the Linux operating system to realize the code universality,reliability and the throughput of massive network messages,and the slave board runs in the way of no operating system naked machine,which is very real-time.In view of the interference of the jitter of the protocol stack and the task scheduling of the operating system,this paper uses the naked machine with stronger real-time performance to record the network message record time stamp in the data link layer of the Lwip protocol stack,which improves the traditional NTP timing accuracy by at least 100 times.The PTP based on IEEE1588v2 protocol achieves 8ns timing accuracy on the main board,and supports all PTP operation modes.For the problem of free oscillation of PTP slave clock,IEEE1588v2+SyncE is introduced to realize PTP timing on the basis of synchronous Ethernet,and then weighted sliding filter is used to fine tune the slave clock to reduce the uncertainty of link delay and the impact of clock quality degradation.Finally,the synchronization accuracy of master-slave clock is improved to within ± 8ns,and the stability reaches picosecond level,which has a higher level and even in the congested network environment,it can realize the fast convergence from clock time.Based on the requirement of the project,a cross platform upper computer software is developed,which can dynamically configure the parameters and real-time running state of high-precision network time synchronization equipment.The improved scheme proposed in this paper significantly improves the timing accuracy of high-precision network time synchronization equipment,and enhances the reliability and flexibility of the equipment,which has been tested in practical engineering applications.