Dealing with Packet Delay Variation in IEEE 1588 Synchronization Using a Sample-Mode Filter

Abstract

In this paper, we characterize the delay profile of an Ethernet cross-traffic network statically loaded with one of the ITU-T network models and a larger Ethernet inline traffic loaded with uniformlysized packets, showing how the average time interval between consecutive minimum-delayed packets increases with increased network load. We compare three existing skew-estimation algorithms and show that the best performance is achieved by solving a linear programming problem on "de-noised" delay samples. This skew-estimation method forms the basis of a new sample-mode algorithm for packet delay variation filtering. We use numerical simulations in OPNET to illustrate the performance of the sample-mode filter in the networks. We compare the performance of the proposed PDV filter with those of the existing sample minimum, mean, and maximum filters and observe that the sample-mode filtering algorithm is able to match or outperform other types of filters, at different levels of network load.

Improved Time-Synchronization Algorithm Based on Direct Compensation of Disturbance Effects

“…Wide variability and disturbances, which are considered as inherent characteristics of an Ethernet-based network environment, are two of the technical difficulties preventing the wide spread of practical PTP applications in power systems [11,12,13,14,15,16,17]. There have been many efforts to provide an adaptive method to compensate the effects of variability and disturbances of network environment [18,19,20], eventually to achieve an effective and fault-tolerant control of time synchronization [21].…”