Context Aware Computing Survey Notes

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?