Research On Optimization Of PTP Algorithm For Asymmetric Networks

As the basic premise for normal operation of asymmetric network measurement and control system,especially to those who is highly sensitive to the time of the industrial wireless network,time synchronization is to determine the system stability and reliability of the core technology.it determines the overall performance of the network system,the system data is valid and the life cycle of a wireless network.IEEE1588 Precision Clock Synchronization Protocol that based on synchronous time packet switching technology is introduced,hereinafter referred to as inhibits PTP(Precision Timing Protocol),in most cases are applied in the cable network application of the agreement,Applying PTP in terms of assuming that assumes the transmission of master-slave clock in the process of positive and negative link is symmetrical,the synchronization accuracy at the influence of transmission delay jitter of symmetry and the accuracy of the timestamp in the process of transmission.compared with the commonly used network synchronization technology such as network time protocol(NTP),simple network protocol SNTP and GPS global positioning system(GPS),the time synchronization accuracy and reliability have been greatly improved.However,the wireless sensor network with these reasons of the positive and negative link asymmetry,external environment factors and theirs own weak wait,wireless channel transmission delay jitter is not symmetrical in data transmission,so it is difficult to satisfy the application inhibits PTP condition.This research firstly analyzes the cause of synchronous error in the wireless sensor network(WSN),and then to mathematical modeling of network system,describe the dynamic system through the state space,time is of the system state variables,the state space model are obtained respectively crystals clock state transition equation and observation equation of inhibits PTP synchronization protocol,the calculation using kalman filter to optimize the process of time synchronization,implementation in the wireless sensor network application inhibits PTP in order to achieve high precision time synchronization.The main contribution of the paper as follows:(1)Analysis the synchronization process of IEEE1588 precise time synchronization protocol(PTP)and the factors of applying PTP in the wireless sensor network(WSN)affecting its performance.(2)Through analyzing the clock nodes in wireless sensor network modeling,and then to obtain the mathematical model of IEEE1588 precise time synchronization protocol over the synchronization process,while the time synchronization of the kalman filter optimization is modeling.(3)Through the MATLAB and Ptolemy II simulation platform for algorithm optimization process simulation,the feasibility of validation in kalman filter under the optimization of precise time synchronization protocol is applied to wireless sensor network.