Research And Implementation Of High Precision Distributed Clock Synchronization Algorithm

High reliability and high precision clock is the basis of different applications in many fields.With the rapid development of computer network,various clock synchronization algorithms have appeared in different fields.Clock synchronization technology aims to solve the problem that the physical or logical clocks of each node in the network system are inconsistent.The unified clock provides the sequential guarantee for the sequential execution of the tasks in the distributed system,provides the security guarantee for financial transactions and process control in the Internet,and provides the quality guarantee for each node in the wireless sensor network to cooperate with each other to complete the detection and perception of complex tasks.The most widely used clock synchronization technology today is NTP,which provides accurate and robust time service for disorderly Internet environment,ensuring that the entire Internet has a basically consistent clock.The current clock synchronization algorithms have many different problems.Firstly,subject to the system clock resolution,these algorithms can only obtain the synchronization accuracy lower than the system clock resolution.Secondly,many algorithms calculate the clock phase deviation based on the symmetry of round-trip delay,while the round-trip delay is often asymmetric in the actual network environment.Thirdly,the clock frequency deviation results in the long-term cumulative timing error.In order to improve the long-term timing accuracy and further reduce the synchronization frequency of the algorithm,it is necessary to compensate the clock frequency deviation.In order to solve the above problems,the main work and contributions of the thesis are concluded as follows:(1)In view of the problem that the clock synchronization algorithm is limited by the lower clock resolution of Windows system,the microsecond level clock resolution is obtained by using the hardware high-performance counter QPC of Windows system through consulting the Microsoft official website information.(2)In view of the problem that most of the existing algorithms assume that roundtrip delay is symmetric,a new algorithm assuming asymmetry of round-trip delay is proposed,and a new clock synchronization timing model is established.We deduce and solve the clock phase deviation between nodes on the basis of the new timing model,and theoretically obtain microsecond clock synchronization accuracy;In view of the problem that most of the existing algorithms ignore the clock frequency deviation,we deduce the formula of relative frequency deviation between nodes and design an algorithm that dynamically adjusts the synchronization period.(3)A high-precision distributed clock synchronization system called HDCSS is further built.By testing the performance of the prototype system,the results show that the new algorithm can obtain 150 us synchronization accuracy in LAN and 500 us synchronization accuracy in WAN.Compared with the same type of clock synchronization algorithm,the network communication overhead of clock synchronization is reduced by 25%.