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A Survey of Context-Awareness. CS 570 Artificial Intelligence Term Project Team Edward : Hee-Jung Yang and Hyeong-Ho Yoo 2005. 12.19. Contents. Context & Context-Awareness General Model of Context-Awareness Sensing the Context Sensing Context Changes Context Modeling Applications

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a survey of context awareness

A Survey of Context-Awareness

CS 570 Artificial Intelligence Term Project

Team Edward : Hee-Jung Yang and Hyeong-Ho Yoo

2005. 12.19

  • Context & Context-Awareness
  • General Model of Context-Awareness
  • Sensing the Context
  • Sensing Context Changes
  • Context Modeling
  • Applications
  • Security & Privacy
  • Conclusion
context and context awareness
Context and Context-Awareness
  • Context

“Context is any information that can be used to characterize the situation of an entity. An entity is a person, place, or object that is considered relevant to the interaction between a user and an application, including the user and applications themselves.”

[Dey and Abowd’s definition]

  • Context-Aware

“A system is context-aware if it uses context to provide relevant information and/or services to the user, where relevancy depends on the user’s task.”

[Dey’s definition]

general model of context awareness
General Model of Context-Awareness
  • Generation
    • Contextual information is obtained from UI or sensor
  • Processing
    • Change raw data to meaningful information
  • Usage
    • Use of contexts and possible reaction as output




sensing the context
Sensing the Context
  • Sensing the Context
    • Raw contextual information
      • Location : location-tracking system (GPS)
      • Time : built-in clock of the computer
      • Light level : photodiode
      • Sound : microphone
    • High-level contextual information
      • User’s current activity : big challenge
        • Machine vision : camera technology, image processing
        • User’s calendar
        • Artificial Intelligence
sensing context changes
Sensing Context Changes
  • Changes of Context
    • Most of contextual information changes as time goes on
    • Context changes can be sensed by
      • Periodic polling
      • Advertising
      • Selective polling
context modeling
Context Modeling
  • Context Model
    • Define and store context data in a machine processable form
  • Context Modeling Approaches
    • Key-Value Models
    • Markup Scheme Models
    • Graphical Models
    • Object Oriented Models
    • Logic Based Models
    • Ontology Based Models
context modeling approaches
Context Modeling Approaches
  • Key-Value-Pairs Models
    • Most simple category of models
    • Not very efficient for more sophisticated structuring purposes
    • Only exact Matching
  • Markup Scheme Models
    • Scheme implements model
    • Typical representatives : profiles
  • Graphical Models
    • Particularly useful for structuring, but usually not used on instance level
context modeling approaches9
Context Modeling Approaches
  • Object Oriented Models
    • Intention behind object orientation is (as always) encapsulation and reusability
  • Logic Based Models
    • Logic defines conditions on which a concluding expression or fact may be derived from a set of other expressions or facts (reasoning)

→ context is defined as facts, expressions and rules

    • High degree of formality
context modeling approaches10
Context Modeling Approaches
  • Ontology Based Models
    • Ontology used as explicit specification of a shared conceptualization

→ strong in the field of normalization and formality

    • Context is modeled as concept and facts
  • Efficient UI
  • Reconfiguration
  • Triggering
  • Memory Retrieval
  • Sharing Experience
security privacy
Security & Privacy
  • Protecting the gathered information
    • Each user have control over their contextual information
  • Not letting the system gather any information
    • User’s approval of information gathering
  • Context-Awareness will become a major trend in future
    • Ubiquitous computing
    • Adapting and tailoring services

[1] B.Schilit and M.Theimer. Disseminating active map information to mobile hosts. IEEE Network, 8(5):22-32, 1994.

[2] A.K. Dey and G.D. Abowd. Towards a better understanding of context and context-awareness. In Proceedings of the Workshop on the What, Who, Where, When and How of Context-Awareness, affiliated with the CHI 2000 Conference on Human Factors in Computer Systems, 2000.

[3] A.K. Dey. Understanding and using context. Personal and Ubiquitous Computing, Vol. 5, 2001.

[4] Strang, T. and Linnhoff-Popien, C. (2004). A context modeling survey. In First International Workshop on Advanced Context Modeling, Reasoning And Management, UbiComp 2004.

[5] Bill N. Schilit, Norman Adams, and Roy Want, Context-aware computing applications. In IEEE Workshop on Mobile Computing Systems and Applications (Santa Cruz, CA, US, 1994)

[6] W3C. Composite Capabilities / Preferences Profile (CC/PP). http://www.w3.org/Mobile/CCPP.

[7] WAPFORUM. User Agent Profile (UAProf). http://www.wapforum.org.

[8] Bauer, J. Identification and Modeling of Contexts for Different Information Scenarios in Air Traffic, Mar. 2003. Diplomarbeit.

[9] Henricksen, K., Indulska, J., and Rakotonirainy, A. Generating Context Management Infrastructure from High-Level Context Models. In Industrial Track Proceedings of the 4th International Conference on Mobile Data Management (MDM2003) (Melbourne/Australia January 2003), pp.1-6.

[10] Indulska, J., Robinsona, R., Rakotonirainy, A., and Henricksen, K. Experiences in using cc/pp in context-aware systems. In LNCS 2574: Proceedings of the 4th International Conference on Mobile Data Management (MDM2003) (Melbourne/Australia, January 2003), M.-S. Chen, P.K. Chrysanthis, M. Sloman, and A. Zaslavsky, Eds., Lecture Notes in Computer Science (LNCS), Springer, pp.247-261.

[11] Schmidt, A., Beigl, M., and Gellersen, H.-W. There is more to context than location. Computers and Graphics 23, 6 (1999), 893-901.

[12] Bacon, J., Bates, J., and Halls, D. Location-oriented multimedia. IEEE Personal Communications 4, 5 (1997).

[13] Chen, H., Finin, T., and Joshi, A. Using OWL in a Pervasive Computing Broker. In Proceedings of Workshop on Ontologies in Open Agent Systems (AAMAS 2003) (2003).

[14] Bill N. Schilit, Norman Adams, and Roy Want, Context-Aware Computing Applications

[15] Peter Brown, Winslow Burleston, Mik Lamming, Odd-Wiking Rahlff, Guy Romano, Jean Scholtz, and Dava Snowdon, Context-awareness: some compelling appplications

applications efficient ui
Applications - Efficient UI
  • More efficient UI as context changes
    • Brighter display in dark place
    • Simplified text when I am moving


dark place & user is moving

applications efficient ui cont d
Applications - Efficient UI (cont’d)
    • Show only important part of clip for poor network bandwidth or small display
    • Different menu for different place
    • Sort people list by distance or show on a map
  • Depend on user’s preference

big display

small display

applications reconfiguration
Applications - Reconfiguration
  • Optimize internal components
    • Choose the fastest connection to server
    • Use the memory of nearby idle computer rather than swapping to disk
    • Print with the closest printer
  • Reconfiguration overhead should be concerned
applications triggering
Applications - Triggering
  • Trigger useful info relevant to current context
    • Car navigation system
    • Explanation about the place where user travels
    • Show cooking guide in kitchen, show work files in office
  • Reminder for specified context
    • When I next meet X, tell him ...
    • When next at a grocery store, buy ...
applications memory r etrieval
Applications – Memory Retrieval
  • Save contexts of each event and retrieve them later
    • Who was the girl with Tom at the theatre yesterday?
    • What was the note I made at a meeting last July in this conference room? I remember Bill and John were there.
  • Object is defined by relative context
    • Filename is the context in which it is made
      • We don’t have to remember the filename
    • Interrupted task is resumed if the context revived
applications sharing experience
Applications – Sharing Experience
  • Refer other people's contexts
    • Travellers download my contexts of my trip here
  • Broadcast my context
    • I send to neighbours the info about cheap theatres here