Accuracy is one of the most important performance metrics in clock synchronization. While state-of-the-art synchronization protocols achieve μsec-order average accuracy, they usually do not focus on the worst case accuracy and do not have any deterministic guarantees. This lack of accuracy guarantee makes it hard for sensor networks to be incorporated into larger systems that require more reliability than e.g., typical environmental monitoring applications do. In this paper, we present a clock synchronization algorithm with deterministic accuracy guarantee. A key observation is that the variability of oscillation frequency is much smaller in a single crystal than between different crystals. Our algorithm leverages this to achieve much tighter accuracy guarantee compared to the interval-based synchronization methods mostly proposed in the literature of distributed systems. We designed an algorithm to solve a geometric problem involving tangents to convex polygons, and implemented that in TinyOS. Experimental results show the deterministic error bound less than 9.2 clock ticks (280 μsec) on average at the first hop, which is close to the simulation results. Further, by a combination with previously proposed synchronization algorithms, it achieves the estimation error of 1.54 ticks at 10 hop distance, which is more than 40% better than FTSP, while giving deterministic error bounds.
The authors of these documents have submitted their reports to this technical report series for the purpose of non-commercial dissemination of scientific work. The reports are copyrighted by the authors, and their existence in electronic format does not imply that the authors have relinquished any rights. You may copy a report for scholarly, non-commercial purposes, such as research or instruction, provided that you agree to respect the author's copyright. For information concerning the use of this document for other than research or instructional purposes, contact the authors. Other information concerning this technical report series can be obtained from the Computer Science and Engineering Department at the University of California at San Diego, firstname.lastname@example.org.
[ Search ]