Research On Slave Clock Synchronization Based On IEEE1588 Protocol

With the rapid development of communication technology,people became increasingly dependent upon the Internet.On the one hand,the public's demand for network functions has become more diversified.On the other hand,people have never stopped pursuing high-bandwidth and high-speed networks.At the same time,it means that the communication network must achieve higher synchronization accuracy.The accuracy of the traditional NTP(Network Time Protocol)is relatively low,which can only reach the synchronization precision of ms level.Although GPS is more accurate,it requires a stricter installation environment,and the IEEE1588 protocol,which replaces the traditional clock synchronization technology,had been put forward.Firstly,the paper introduces the development and synchronization requirements of packet transport network,and the evolution of synchronous network architecture in 5G communication.Then it focused on the IEEE 15 88 protocol in PTN(Packet Transport Network)technology.Through the analysis and mathematical modeling of influencing factors on the performance of synchronization,a PID(Proportion Integral Derivative)control system based on Kalman filter is proposed,which achieves the synchronization precision of ns and can meet the basic synchronization requirements of 3G,4G and 5G communication.The main innovation of this paper lies in the following three aspects:(1)According to the three factors that affect the synchronization performance of IEEE1588 system:packet processing delay,transmission line delay,clock stability,the corresponding solutions are analyzed.Taking into account the different clock stability,the master-slave clock system is modeled.(2)Gaussian white noise is used to simulate the error introduced in the observation process and the frequency jitter caused by the instability of the clock crystal,and the Kalman filter is used to eliminate it.(3)Because of the frequency drift caused by the instability of the master-slave clock,the PID controller is used to eliminate the linear growth of the constant deviation.If the synchronization period is 0.5s,the deviation of the master clock and the slave clock can quickly reach a minimum of 1?s within 4 s,based on the PID control after Kalman filter.If the synchronization period is further reduced to 0.01s,the synchronization accuracy can reach 3ns,which is better than the synchronization error of 10?s specified in the IEEE 1588 protocol to meet the time synchronization requirement of ±1.5?s for the basic services in the 5G network and the ns-level requirements in some specific scenarios.