Research On Synchronization Technology Based On IEEE1588 Protocol For Optical Transmission Network

Optical transmission network is the next-generation transmission network technologies, like the traditional SDH. It is necessary to support the system clock synchronization. IEEE1588 is the high-precision synchronization protocol that can support both frequency and time synchronization of transport network. Compared with the existing synchronization technology, it has obvious advantages. So IEEE1588 is a critical synchronization technology of OTN networking applications. In this paper, the different clock of IEEE1588v2 types in OTN network synchronization scheme is explained in detail, and the advantages and disadvantages of each scheme is analyzed. It is worth noting that the problem is that most of the equipment of transport network can not support 1588v2 transparent clock agreement, so synchronization in the actual network will inevitably produce network transmission jitter error(including link delay and residence delay inside the equipment),which reduces the synchronous precision. On the other hand, due to the instability of clock crystals, the frequency drift phenomenon exists between the local clock and standard clock, so the error between the master clock and the local clock is accumulated. This dissertation focuses on mainly these two kinds of error correction, by two improved and algorithms improves the timing precision of the IEEE1588.Concerning the network transmission jitter error, Kalman smoothing filter correction algorithm is proposed. Based on IEEE1588 delay request response mechanism, the noise model of network jitter error is deduced. The noise is similar to Gaussian noise. In the process of synchronizing, it is stacked in the standard clock synchronization message, is sent to the clock. It is a necessary add a kalman smoothing filter module in the clock, so as to decrease network jitter error.A single neuron adaptive PID controller is presented in order to eliminate the frequency drift of the local clock, to improve the accuracy of the network timing. This method combined neural network with PID control, so as to realize the real-time adjustment of parameter and improve the control precision. In addition, the mean filter module is used to eliminate the local clock frequency jitter. The simulation result shows that the proposed method can significantly improve the PTP synchronization accuracy.