Servo design for improved performance in software timestamping-assisted WLAN synchronization using IEEE 1588

The clock servo is an essential constituent of distributed clock synchronization systems and a determining factor for the synchronization performance. This paper focuses on the clock servo design for better accuracy and precision in software-based clock synchronization over WLAN. The behaviour of the clock servo is analysed in this work and errors arising from software timestamps and the oscillator are evaluated. These errors are then used to investigate the operating conditions of the servo loop which results in the least synchronization offset and jitter. Results are obtained through simulations and then verified experimentally by a prototypical implementation. The results indicate that the synchronization performance is optimal when the servo relies more on the oscillator and less on the software timestamps.

[1]  G. Giorgi,et al.  Modeling and Simulation Analysis of PTP Clock Servo , 2007, 2007 IEEE International Symposium on Precision Clock Synchronization for Measurement, Control and Communication.

[2]  G. Gaderer,et al.  Limits of synchronization accuracy using hardware support in IEEE 1588 , 2008, 2008 IEEE International Symposium on Precision Clock Synchronization for Measurement, Control and Communication.

[3]  Thilo Sauter,et al.  Achieving a Realistic Notion of Time in Discrete Event Simulation , 2011, Int. J. Distributed Sens. Networks.

[4]  John C. Eidson,et al.  Measurement, Control, and Communication Using IEEE 1588 , 2006 .

[5]  Thilo Sauter,et al.  The Three Generations of Field-Level Networks—Evolution and Compatibility Issues , 2010, IEEE Transactions on Industrial Electronics.

[6]  Henning Trsek,et al.  An isochronous medium access for real-time wireless communications in industrial automation systems - A use case for wireless clock synchronization , 2011, 2011 IEEE International Symposium on Precision Clock Synchronization for Measurement, Control and Communication.

[7]  Thilo Sauter,et al.  Improving Fault Tolerance in High-Precision Clock Synchronization , 2010, IEEE Transactions on Industrial Informatics.

[8]  M. Branicky,et al.  Design Considerations for Software Only Implementations of the IEEE 1588 Precision Time Protocol , 2005 .

[9]  R. Exel,et al.  Clock synchronization in IEEE 802.11 wireless LANs using physical layer timestamps , 2012, 2012 IEEE International Symposium on Precision Clock Synchronization for Measurement, Control and Communication Proceedings.

[10]  Henning Trsek,et al.  Towards high accuracy in IEEE 802.11 based clock synchronization using PTP , 2011, 2011 IEEE International Symposium on Precision Clock Synchronization for Measurement, Control and Communication.

[11]  D. Macii,et al.  A master-slave synchronization model for enhanced servo clock design , 2009, 2009 International Symposium on Precision Clock Synchronization for Measurement, Control and Communication.