1 / 32

Context Aware Computing Survey Notes

Context Aware Computing Survey Notes. Changqing Zhou To discuss with Prof. Shekhar on September 26, 2002. Goal. Survey a broad variety of areas Get familiar with the terminologies Identify potential interesting points Whats next. Summary. UniComp 2002 Latest technology

tessica
Télécharger la présentation

Context Aware Computing Survey Notes

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Context Aware Computing Survey Notes Changqing Zhou To discuss with Prof. Shekhar on September 26, 2002

  2. Goal • Survey a broad variety of areas • Get familiar with the terminologies • Identify potential interesting points • Whats next

  3. Summary • UniComp 2002 • Latest technology • Context aware survey, Chen, Dartmouth • Complete survey • Location aware by Want, Intel • Latest industry implementation • Location systems survey paper, Hightower, University of Washington • Mobile objects • Database perspective: data model, storage, query, distributed comp., bench mark

  4. CampusAware, UniComp 2002 • Jenna Burrell, Cornell, Intel • a campus tour system for Palm Pilots • uses GPS to find the user's location • alert users when information related to their location is available • users can add their own notes and locations • not able to detect location precisely enough to prevent user confusion • Related work: Normad Project: Radio network + laptops

  5. MUSE • Stefanone, Cornell, 2002, sponsored by Intel • use hand-held computers to provide both visual and audio supplements to exhibits in the Johnson Museum at Cornell University • hand-held computer "reads" your location and presents information specific to that artifact.

  6. Mobile Reality, UniComp 2002 • Siemens • A PDA-Based Multimodal Framework Synchronizing a Hybrid Tracking Solution with 3D Graphics and Location-Sensitive Speech Interaction

  7. Rememberer, UniComp 2002 • HP • A Tool for Capturing Museum Visits • Use camera/tags tracking the tour, not location based • RFID tags: credit card shape and mounted in watch • PDA with wireless 802.11 network • User experience research

  8. Privacy Awareness System, UniComp 2002 • Institute of Information Systems, ETH Zurich • Privacy proxies running through web service • Privacy Aware database, pawDB, stores P3P policies in Oracle 8i

  9. Location Model, UniComp 2002 • Jiang and Steenkiste, CMU, Networking • Select name from printer where distance(location,`ali://cmu/wean-hall/floor3/3100-corridor#(10,10,0)') <10 • PostgreSQL database system • Hierarchical(address): No position • Coordinate(longitude, latitude, altitude): No hierarchy • Hybrid data model

  10. A Broadband Ultrasonic Location System, UniComp 2002 • University of Cambridge • Ultrasonic location systems with narrowband transducers to broadband transducers • Function in high levels of environmental noise

  11. Location of Mobile Devices Using Networked Surfaces, UniComp 2002 • Cambridge University • Estimate device locations on the Networked Surface prototype • Evaluates the location accuracy obtained, using simulations, measurements, and visualization • Improving the location accuracy are also investigated

  12. SmartMoveX on a Graph, UniComp 2002 • Microsoft • an active badge system in which a small radio transmitter attached to the person • Receivers connected to existing PCs • compute locations based on signal strength • Modeling the data with a hidden Markov model, use Viterbi algorithm to compute optimal paths based on signal strengths over the node graph. • The average location error was 3.05 meters

  13. A Survey of Context-Aware Mobile Computing • Dartmouth College • Wireless connections (1) • Context definition (1) • Context aware computing types (1) • Applications (6) • Sensing context (1) • Location model (1) • System infrastructure (1) • Security and privacy (1)

  14. Wireless Connection Types • Wireless Cellular networks: Palm VII connects to www.palm.net • Wireless LAN networks: IEEE 802.11, PCMCIA, CompactFlash, SpringBoard • Wireless PAN (Personal Area Network) or BAN(Body Area Network): Bluetooth, IEEE802.15, short-range IR

  15. Context Definition • Computing context: network connectivity, communication cost, communication bandwidth, nearby resource • User context: user profile, location, social situation • Physical context: lighting, noise, traffic condition, temperature • Time Context: time of a day, week, month, season of a year

  16. Context Aware Computing • Active context awareness: an application automatically adapts to discovered context, by changing the application’s behavior • Passive context awareness: an application presents the new or updated context to an interested user or makes the context persistent for the user to retrieve later • Active context awareness is more interesting

  17. Classic Context Aware Applications • Call Forwarding • Olivetti, active, user location, based on active Badge • Location of the user is presented to the receptionist and the call will be forwarded • Recently, automatically forward • Teleporting • Olivetti/AT&T, active, user location, workstation location, based on active Badge • Application follows the user while he moves around • Augment resource-poor PDA with surrounding computing resources

  18. Classic Context Aware Applications • Active Map • XEROX PARCTab, passive, user’s location • Every room has a wireless station and room number of the user is collected and updated on a map • Mobisaic Web Browser • U of Washington, active, location and time • Hypertext links contain environment variables, extending standard browser

  19. Classic Context Aware Applications • Shopping Assistant • AT&T Bell Lab, active, locaiton • Guide shoppers throughout the store and provide information • Cyberguide • Georgia IT, passive/active, location and time • Outdoor/GPS, indoor/TV Remote based IR • Travel diary is compiled and recommendation

  20. Classic Context Aware Applications • Conference Assistant • Georgia IT, passive/active, location, time and schedule of presentations • Recommend presentations to attendees based on schedule, topic, location and research interest • People and Object Pager, U of Kent • Fieldwork, U of Kent

  21. Classic Context Aware Applications • Adaptive GSM phone and PDA at Starlab • Office Assistant at MIT • Location-aware Information Delivery at MIT

  22. Application Conclusion • Few contexts other than location have been used • Context history is rarely used • Any reliance on the user to explicitly provide context information, proves to be obtrusive and inconvenient • No killer applications found

  23. Sensing the Context - Location • Outdoor • GPS 10-20 meters • Connectivity-based localization 3 meters, radio model, IEEE 802.11 cellular, mobile IP • Indoor • Most research projects use their own location tracking system based on IR or RF or both • Bat system at AT&T, ultrasonic and radio signals based, 15 cm, tracks both location and direction • Crecket system at MIT, device determines location • RADAR at Microsoft, non-cellular, RF signal strength

  24. Location Data Model • Symbolic and Geometric • Key-value pairs • Tagged encoding • OO Model • Logic based

  25. System Infrastructure • Centralized • Location Information Server at Phillip • Centralized maintenance of contexts. • Trigger and callback • Scalability? Not necessarily • Distributed • Rome system at Stanford • No context share • More privacy

  26. Security and privacy • In general hard to provide • Provide user controllable tradeoffs • Legislation • Addressed in one paper in UbiquitousComp 2002

  27. Roy Want Paper • Roy Want, Xerox, Intel • Olivetti active badge: first location aware application • Xeriox PARCTab: true palm size computer • Major players: IBM’s Pervasive computing, Microsoft’s ubiquitous computing, Intel, Xerox, HP’s CoolDown, AT&T’s Sentient computing

  28. GPS • Phillips, STMicro-electronics • SnapTrack, GPS integrated onto Qualcomm CDMA chipset • GPS information needs to be augmented, such as direction. • HP CoolDown group uses an electronic compass

  29. Short-range radio • Bluetooth short range radio standard • BlueSoft • Ericsson’s R520M Bluetooth cell phone • Intel’s Personal Server • No display, no input • Wirelessly connected through Bluetooth radio • Utilizes local display and input and other resources • AT&T’s Sentient • Ultrasonic and radio • Fine spatial granularity, 3D space in a room

  30. Location Systems - Hightower • A Taxonomy to evaluate location-sensing systems • Location System Properties • Physical position and symbolic position • Absolute versus relative • Localized location computation, distributed or centralized • Accuracy(how good) and precision(how often) • Scale • Recognition • Cost • Limitations

  31. Questions • Are we interested in location aware computing? • Integrate our directional model into location model to offer “Real Guide”? • Integrate data mining technique into context history? Frequent sub-tree mining? Pure data analysis is not location aware computing because it is offline. Application state changes based not only on the current context, but also context history? • Any location/time aware data from MinDot? • Map Compression?

  32. Questions • Are we interested in building a location aware prototype? • Pros of building a prototype(hands on experience, public awareness, experiment, system involving) • I am very interested and I have strong system building skills. I will consider fulltime participation. (I am a web infrastructure tech lead, technically leading 10 developers, building distributed, scalable, secure and privacy sensitive web and B2B applications) • Is it possible? Equipment and expertise? Outdoor GPS? Indoor CS wireless LAN? Campus tour system? • Collaboration with networking or system people?

More Related