Optimal Clock Synchronization Revisited: Upper and Lower Bounds in Real-Time Systems

  • Heinrich Moser
  • Ulrich Schmid
Part of the Lecture Notes in Computer Science book series (LNCS, volume 4305)


This paper introduces a simple real-time distributed computing model for message-passing systems, which reconciles the distributed computing and the real-time systems perspective: By just replacing instantaneous computing steps with computing steps of non-zero duration, we obtain a model that both facilitates real-time scheduling analysis and retains compatibility with classic distributed computing analysis techniques and results. As a by-product, it also allows us to investigate whether/which properties of real systems are inaccurately or even wrongly captured when resorting to zero step-time models. We revisit the well-studied problem of deterministic internal clock synchronization for this purpose, and show that, contrary to the classic model, no clock synchronization algorithm with constant running time can achieve optimal precision in our real-time model. We prove that optimal precision is only achievable with algorithms that take Ω(n) time in our model, and establish several additional lower bounds and algorithms.


Schedule Policy Clock Synchronization Computing Step Message Delay Time Message 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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Copyright information

© Springer-Verlag Berlin Heidelberg 2006

Authors and Affiliations

  • Heinrich Moser
    • 1
  • Ulrich Schmid
    • 1
  1. 1.Technische Universität WienViennaAustria

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