Periodic Patterns in Human Encounters

Research talk.
Venue: Research Retreat, Cardiff University School of Computer Science & Informatics.

Transcript

1. | Research Retreat | May 2011 |
   Matt Williams
   CS&I Research Retreat
   May 2011
   

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2. | Research Retreat | May 2011 |
   Periodic Patterns in Human
   Encounters
   Matt Williams
   CS&I Research Retreat
   May 2011
   

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3. | Research Retreat | May 2011 |
   Human encounters
   

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4. | Research Retreat | May 2011 |
   Why study human encounters?
   opportunistic content sharing
   virus spreading patterns
   

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5. | Research Retreat | May 2011 |
   Periodicity and patterns in human encounters
   

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6. | Research Retreat | May 2011 |
   • How prevalent are periodic encounter patterns in
   human networks?
   • How does the presence of periodic encounters
   affect information flow?
   • Can periodic patterns be detected and used to
   improve content sharing in opportunistic
   networks?
   Research questions
   

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7. | Research Retreat | May 2011 |
   How do we study human encounters?
   Smartphone Bluetooth
   encounters
   (@MIT)
   WiFi access point visits
   (@Dartmouth Campus)
   Foursquare venue visits
   (@Cardiff +others)
   

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8. | Research Retreat | May 2011 |
   How do we study human encounters?
   Smartphone Bluetooth
   encounters
   (@MIT)
   WiFi access point visits
   (@Dartmouth Campus)
   Foursquare venue visits
   (@Cardiff +others)
   

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9. | Research Retreat | May 2011 |
   • A group of nodes that regularly encounter one another
   with a given period
   Periodic encounter communities (PECs)
   

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10. | Research Retreat | May 2011 |
    • In opportunistic networks, a decentralised algorithm is
    needed
    Detecting PECs in OppNets
    

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11. | Research Retreat | May 2011 |
    Detecting PECs in OppNets
    

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12. | Research Retreat | May 2011 |
    • Period: the gap between
    reappearances of the community
    (24 hrs, 7 days, etc.)
    • Diameter: the distance between the
    most distant nodes in the community
    Properties of PECs
    diameter = 4
    

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13. | Research Retreat | May 2011 |
    

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14. | Research Retreat | May 2011 |
    • Diameter and period give us a theoretical
    worst-case for the time needed for all nodes to
    send messages to each other
    • In practice, how does information sharing
    compare to the worst-case?
    Information sharing
    

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15. | Research Retreat | May 2011 |
    in 75% of PECs,
    information sharing
    took less than 1/2 the
    worst-case time
    

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16. | Research Retreat | May 2011 |
    • PEC detection relies on a crisp definition
    • Inherent uncertainty in encounter times poses a
    problem
    Limitations
    

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17. | Research Retreat | May 2011 |
    • Dealing with fuzziness: borrow a technique from neuroscience!
    • Spike train synchrony: measures the similarity of bursting patterns
    of neurons
    Ongoing work: spike train methods
    Kreuz et al. 2009
    

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18. | Research Retreat | May 2011 |
    Human encounter ‘trains’
    Week 1
    Week 2
    Week 4
    Week 3
    

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19. | Research Retreat | May 2011 |
    Human encounter ‘trains’
    Week 1
    Week 2
    Week 4
    Week 3
    

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20. | Research Retreat | May 2011 |
    Regions of regularity
    Kreuz et al. 2009
    

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21. | Research Retreat | May 2011 |
    • Periodic encounter patterns exist and can be
    automatically detected
    • Evidence that periodic encounter patterns influence
    information flows in human encounter networks
    • Spike train methods are a promising solution for the
    detection of ‘fuzzy’ encounter patterns
    Summary
    Thanks for listening!
    

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22. | Research Retreat | May 2011 |
    References
    M.J. Williams, R.M. Whitaker, S.M. Allen, Decentralised detection of periodic
    encounter communities in opportunistic networks, Ad Hoc Networks,
    10.1016/j.adhoc.2011.07.008.
    T. Kreuz, D. Chicharro, R. G. Andrzejak, J. S. Haas, and H. D. I. Abarbanel,
    Measuring multiple spike train synchrony, Journal of Neuroscience
    Methods, vol. 183, no. 2, pp. 287–299, 2009.
    Attribution
    Library Courtyard. nevolution. http://www.flickr.com/photos/nevolution/
    2906377551/
    

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