On the Interaction of Clocks, Power, and Synchronization in Embedded Sensor Nodes

In Under Submission , 0 pages , March 2009.

NESL Technical Report #: TR-UCLA-NESL-200903-02

Sensor networks have matured beyond academic research with industry now considering the advantages of using wireless sensors. With this growth, reliability and real-time demands increase, thus timing becomes more and more relevant. At the same time, the small power budget introduces an additional challenge to time synchronization. While power has been a concern to time synchronization protocol developers, they mainly focused on reducing the amount of messages the protocol transmitted, whereas the power consumption of the underlying local clock has vastly been ignored. This work investigates upper bounds on time synchronization accuracy. We find that the error can be categorized into two regions, one where the quantization error dominates, and a second one where temperature induced frequency error overshadows the effects of quantization. Based on these two regions, we find the optimal resynchronization interval balancing synchronization accuracy and power consumption. Using these results, we show the impact of different clock technologies on the resynchronization requirements of a simple time synchronization protocol.

• Thomas Schmid
• Roy S Shea
• Zainul M Charbiwala
• Jonathan Friedman
• Young H Cho
• Mani B Srivastava

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• XCXT : Crystal Compensated Crystal Based Timer

Journal Paper