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IEEE 1588 Style Synchronization over a Wireless Link

Abubakari, Hamza
http://rave.ohiolink.edu/etdc/view?acc_num=akron1226631636

Abstract Details

2008, Master of Science, University of Akron, Electrical Engineering.
Networked embedded systems, which rely on inexpensive nodes (hardware) and interact in a peer-to-peer manner over wireless links, offer new opportunities for systems architecture and design in a variety of domains. The local clocks in such nodes present relatively large clock offsets at the application level. Achieving time synchronizationacross such nodes, however, remains a challenge. The IEEE 1588 time synchronization protocol specifies how such synchronization can be achieved over wired networks. The wireless domain further exacerbates the problem of achieving time synchronization because of high packet losses and low bandwidth. This thesis presents the design and implementation of a technique for synchronizing clocks, over a wireless link, of a pair of resource-constrained nodes. This is a software-only implementation, in the sense that there is no special hardware required to support the technique. This design builds on a prior technique that compensated clock offset using a conventional digital filter and a Proportional-Integral (PI) controller using IEEE 1588 messages over a wired network. To mitigate the effects of packet-losses in the wireless environment this design tracks and compensates for skew, which is the rate of change of the offset. Because the skew was determined to be gaussian distributed, a linear Kalman filter was used to track the skew. This filtered skew was used as the tracking signal by the PI controller and the output of this controller was used to discipline the clock by modulating the clock rate to match that of the leader. Experimental results demonstrate that this technique, which used a Kalman filter and compensated for skew, performs better than the prior technique that used a conventional digital filter and compensated for offset. These results demonstrate that this technique is resilient against packet losses and achieves better accuracy and stability for both single-hop and multi-hop scenarios. In the future, this technique can serve as a foundation to improve determinism and predictability in networked embedded systems.
Shivakumar Sastry, PhD (Advisor)
77 p.
Computer Science; Electrical Engineering
clocks; SYNCHRONIZATION; preamble; MAC; o¿¿¿¿¿¿¿sets; messages; ¿¿¿¿¿¿lter

Recommended Citations

Citations

  • Abubakari, H. (2008). IEEE 1588 Style Synchronization over a Wireless Link [Master's thesis, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1226631636

    APA Style (7th edition)

  • Abubakari, Hamza. IEEE 1588 Style Synchronization over a Wireless Link. 2008. University of Akron, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1226631636.

    MLA Style (8th edition)

  • Abubakari, Hamza. "IEEE 1588 Style Synchronization over a Wireless Link." Master's thesis, University of Akron, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=akron1226631636

    Chicago Manual of Style (17th edition)

akron1226631636
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© 2008, all rights reserved.
This open access ETD is published by University of Akron and OhioLINK.