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Synchronization inspired by fireflies

Synchronization inspired by fireflies. Iva Bojić University of Zagreb, Croatia Faculty of Electrical Engineering and Computing Department of Telecommunications Summer School of Science 201 2 August 7 , 201 2 , Višnjan , Croatia. Round of applause u se your hands and move your body .

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Synchronization inspired by fireflies

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  1. Synchronization inspired by fireflies Iva Bojić University of Zagreb, Croatia Faculty of Electrical Engineering and Computing Department of Telecommunications Summer School of Science2012 August 7, 2012, Višnjan, Croatia

  2. Round of applauseuse your hands and move your body  S3++ 2012

  3. Group ofpeoplesame rhythmus S3++ 2012

  4. Heterogeneous Machine-to-Machine Systemssame time S3++ 2012

  5. Logical questionscan we go home? • How hard it is to synchronize different clocks? • Why do we need time synchronization? • How can we achieve time synchronization? S3++ 2012

  6. Outlinetry to give logical answers… Research motivation Biologically-inspired computing Firefly-inspired synchronization Results from the laboratory setting Conclusion S3++ 2012

  7. Computer clockhow does it work? • How is this possible? Quartz crystals are manufactured for frequencies from a few tens of kHz to tens of MHz A clock is an electronic device that counts oscillations in a crystal at a particular frequency S3++ 2012

  8. Problemno global notion of time • In distributed systems each node has its own clock and its own notion of time • In practice these clocks drift apart accumulating errors over time (1 second every 11 days) S3++ 2012

  9. Need for (speed?)time • Global notion of time is prerequisite for: • common resource sharing (e.g. channel) • depend events tracking (e.g. consistency of distributed databases) • simultaneous events detection (e.g. data collection) Frequency division multiple access Time division multiple access S3++ 2012

  10. Time synchronizationdifferent algorithms • Time synchronization provides a common time scale for local clocks of nodes in distributed systems B. Sundararaman, U. Buy and A. D. Kshemkalyani: Clocksynchronization for wirelesssensornetworks: A Survey, Ad HocNetworks 3, pp. 281-323 (2005) S3++ 2012

  11. Biologically-inspired computingbiology applied in distributed systems • Nature is a enormous and a highly complex system • processes are done without any centralized control • processes are self-sustainable and self-organized • Self-organization is a process where some form of global order arises out of the local interactions between the components of an initially disordered system S3++ 2012

  12. Self-synchronizationin nature S3++ 2012

  13. Self-synchronizationin humans S3++ 2012

  14. Pulse coupled oscillators modelone firefly • If oscillators are not coupled, their state variables change following only their own excitations • xi denotes state variable xi(t) = fi(t) • ti* denotes a moment when i-thoscillatorflashes R. E. Mirollo and S. H. Strogatz. Synchronization of pulse-coupled biological oscillators. SIAM J. Appl. Math. 50: pp.1645-1662 (1990) S3++ 2012

  15. Pulse coupled oscillators modeltwo fireflies • If oscillators are coupled • state variable xi is adjusted upon the reception of flashes from the others • xi(t) = fi(t) + ϵijgij(t) • ϵijis a coupling constant • gij(t) is a coupling function between i-th and j-th oscillators R. E. Mirollo and S. H. Strogatz. Synchronization of pulse-coupled biological oscillators. SIAM J. Appl. Math. 50: pp.1645-1662 (1990) S3++ 2012

  16. Pulse coupled oscillators modellimitations • Pulse coupled oscillators model assumptions • no oscillators with a faultybehavior that desynchronizes the network • oscillators are connected in afully-connected network • oscillators cannot join or leave the network nor change their positions in the network (i.e. no mobility) • oscillators are the same (i.e. have same frequencies) • no delays in themessage exchangeamong oscillators S3++ 2012

  17. Robustnesswithoscillators with faulty behavior • We embedded a cryptographic mechanism in the pulse coupled oscillators model to ensure robustness • We used the logical operation exclusive disjunction (i.e. XOR) • provides protection from an attack • does not have a negative effect on the time needed for synchronization S3++ 2012

  18. Resultsrobustness S3++ 2012

  19. Conclusionscan we go home? NOW WE CAN!!!!!!!!!!!!!!!!!!! • How hard it is to synchronize different clocks? • Why do we need time synchronization? • How can we achieve time synchronization? S3++ 2012

  20. Questions? S3++ 2012

  21. Summationexclusive disjunction Input Output A B 0 0 0 0 1 1 1 0 1 1 1 0 S3++ 2012

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