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Context-Aware Computing Overview and Case Studies. Marko Jurmu MediaTeam Oulu Group University of Oulu Finland March 13 th , 2007. Outline:. Fact Sheet: Finland Motivation Definitions of Context Effects of Context-Awareness Example Application Domains CASE 1: Connectivity Management

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context aware computing overview and case studies
Context-Aware ComputingOverview and Case Studies

Marko Jurmu

MediaTeam Oulu Group

University of Oulu


March 13th, 2007

  • Fact Sheet: Finland
  • Motivation
  • Definitions of Context
  • Effects of Context-Awareness
  • Example Application Domains
  • CASE 1: Connectivity Management
  • CASE 2: RFID Symbolic Tags
  • CASE 3: Wearable Sensors
  • Raised Issues
  • References
fact sheet suomi finland
Fact Sheet: Suomi (Finland)
  • Population: 5.3 mi
  • Area: 330.000 km2 (127.000 sq mi)
  • Independent since: Dec. 6, 1917
  • Capital: Helsinki (ca. 1 mi)
  • Home of:
    • Santa Claus
    • NOKIA
    • Linus Torvalds
    • Jari Litmanen
    • Teemu Selänne
    • Jari Kurri
  • Traditional computer systems execute blindly
    • Pre-defined application logic
    • Static user interfaces that require explicit attention
  • New kind of computing
    • Mobility is becoming a norm
    • Applications execute in less static


  • What can be done?
    • Enable computer systems to sense their surroundings
    • Encode changes in the surroundings to reflect to the application behavior
motivation cont d
Motivation cont’d
  • But:
    • Coding explicit reflections into applications is laborous
    • Applications do not necessarily understand all changes
    • Applications may not be able to collect all the necessary information
  • We need:
    • Supporting platforms that facilitate application execution
    • Ways to gather disparate information and provide it in a unified way
    • Mechanisms to provide information without loss in semantics
  • These are the main research problems of context-aware computing
definitions of context
Definitions of Context
  • Schmidt et al. [1]:
    • Context is a series of transient hierarchical feature spaces
    • Very systematic definition
definitions cont d
Definitions cont’d
  • Dey [2]:
    • ”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 the application themselves.”
    • Very loose definition, reflects well the common paradox in context-aware computing:
      • Applications can never be made aware of all possible context
      • In practice, the subset of context utilized by applications is strongly dictated by the sensing capabilities of underlying computer system
definitions cont d1
Definitions cont’d
  • Dey’s definition of context-awareness [2]:
    • ”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”
    • Important contrast: Previous discussion was strongly related to providing information that enables dynamic changes in the execution of the application
      • According to this definition, application is also context-aware if it can use context to filter the information presented to the user
levels of context
Levels of Context
  • In their work [1], Schmidt et al. define 4 levels of context:
    • Raw sensor data
      • Readings acquired fromindividual sensors
    • Cues
      • Abstracted sensor data,possibly temporally aggregated
    • Context
      • Description of the current situationon an abstract level
    • Scripting
      • Allowing applications to benefitfrom context through simplescripts
effects to application logic
Effects to Application Logic
  • Context-aware applications need to be designed differently from static applications:
    • Agile behavior on the face of rapid changes
    • Platform independence is required
    • Logic is distributed to better reflect the variance in the computing environments
  • The reflection to context changes can be encoded in several ways:
    • Definition of explicit rules and conditions
    • Increasing / decreasing application functionality
    • Dynamically maintaining the FSMs that controlthe application
effects to interaction
Effects to Interaction
  • Traditional interaction:
    • Based on explicit user input
    • Static UIs with a certain conceptual models
    • User overwhelmed with unnecessary information
      • Situations worsens with ever-increasing information
  • Context-aware interaction:
    • Based on combination of implicit and explicit I/O
      • Implicit interaction does not require additional cognitive load
    • UIs that filter information and lessen the explicit controlling
    • More intuitive interaction models for users can be enabled
example application domains
Example Application Domains
  • Location-aware applications:
    • Map-based guidance
    • Focused advertising
    • Weather / traffic services
  • Network-aware applications:
    • Video streaming
    • VoIP
    • File management operations
  • Combinations of these and other contexts:
    • Basically the list is endless, the following presents 3 enablers
case 1 connectivity management
CASE 1: Connectivity Management
  • Background:
    • Currently, wireless networking appearsthrough heterogeneous overlappingaccess networks
    • Mobility of the users is causing constantchanges to the configuration of activeradio interfaces
    • Connectivity can be based oninfrastructural or ad-hoc links
    • Networking applications in the mobile device need coherent mechanisms to cope with networking conditions
case 1 cont d
CASE 1 cont’d
  • Solution [3]:
    • Introduce a persistent networking interface for applications
    • Applications only see channels, and can specify different policiesfor network utilization
case 2 rfid symbolic tags
CASE 2: RFID Symbolic Tags
  • Background:
    • Invoking specific actions from mobile phone requires the navigation ofhierarchical menus
    • Can be very time-consuming, anddoes not guarantee that allaction-related parameters are entered correctly
    • All in all: Highly explicit UI
case 2 cont d
CASE 2 cont’d
  • Solution [4]:
    • Add RFID tags with intuitive symbols to the environment
    • Tag has action-related parameters encoded, so menu-based setting is not required
    • Still, users only see symbolic actions that can be invoked by touch
case 3 wearable sensors
CASE 3: Wearable Sensors
  • Background:
    • Computer systems need information regarding the activities of the user to be able to support them
    • Having basic context like location is not necessarily enough
    • Activity is also correlated with artifacts being currently utilized
case 3 cont d
CASE 3 cont’d
  • Solution [5]:
    • Equip users with wearable sensors
    • Additional sensors in artifactsgive information on usage
raised issues
Raised Issues
  • User control
    • Context-awareness takes control away from users
    • What is the right amount of user control?
      • User must feel that he/she is in control of the system
    • Two extremes:
      • Application asks everything from user (not very feasible)
      • (certainly not very feasible)
  • Privacy
    • Context-awareness requires the acquisition and storaging of information related to users and their surroundings
    • How to ensure correct management and avoid leakages?
    • How to avoid the collection of sensitive information?
future trends
Future Trends
  • From application point-of-view, mobility is turning multidimensional
    • Over administrative domain boundaries
    • Over device boundaries
    • Over social boundaries
  • Living environments are increasingly saturated with intelligent electronics
    • Available services increase
    • Digital and physical worlds increasingly overlap
  • Challenges lie ahead especially in dynamic session management between environments and mobile users

[1] Schmidt, A., Beigl, M. & Gellersen, H.-W. (1999), There is more to context than location, Elsevier Computer and Graphics Journal 23(6): 893-901.

[2] Dey, A. (2000), Towards better understanding of context and context-awareness, CHI 2000 Workshop on the What, Who, Where, When, Why and How of Context-Awareness.

[3] Sun, J., Riekki, J., Jurmu, M. & Sauvola, J. (2005), Adaptive connectivity management middleware for heterogeneous wireless networks, IEEE Wireless Communications 12(6): 18-25.

[4] Riekki, J., Salminen, T. & Alakärppä, I. (2006), Requesting pervasive services by touching RFID tags, IEEE Pervasive Computing 5(1): 40-46.

[5] Pirttikangas, S., Fujinami, K. & Nakajima, T. (2006), Feature selection and Activity Recognition from Wearable Sensors, Proc. International Symposium on Ubiquitous

Computing Systems (UCS2006), Seoul, Korea, Oct. 11-13, 2006, pp. 516-527.