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Some Computer Science Issues in Ubiquitous Computing

Some Computer Science Issues in Ubiquitous Computing. Communications of the ACM 1993 Mark Weiser Presenter: Junghoon Kim kjh@mmlab.snu.ac.kr. Contents. Introduction Paradigm Shift What is Ubiquitous Computing? Virtual Reality Ubiquitous Issues Design Approach Hardware Issues

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Some Computer Science Issues in Ubiquitous Computing

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  1. Some Computer Science Issues in UbiquitousComputing Communications of the ACM 1993 Mark Weiser Presenter: Junghoon Kim kjh@mmlab.snu.ac.kr

  2. Contents • Introduction • Paradigm Shift • What is Ubiquitous Computing? • Virtual Reality • Ubiquitous Issues • Design Approach • Hardware Issues • Network Protocols • Interaction Substrate • Applications • Privacy of Location • Computational Methods • Summary

  3. Introduction - Paradigm Shift- What is Ubiquitous Computing?- Virtual Reality

  4. Paradigm Shift • Traditional computer • Isolated from the overall situation • Needed to attend to use • Future computer • Intimate computer • Rather like a human assistant • Challenge • Create a new kind of relationship of people to computer

  5. What is Ubiquitous Computing? • Definition • Ubiquitous computing enhances computer use by making many computers available throughout the physical environment, while making them effectively invisible to the user

  6. Virtual Reality • From rising star to fallen angel • Believed to enact the principles • Makes it possible for computers to get out of the traditional work way (supports intuitive interaction) • Problems • Very expensive to provide sufficiently realistic simulation • Cuts people from real world

  7. Ubiquitous Issues - Design Approach- Hardware Issues- Network Protocols- Interaction Substrates- Applications- Privacy of Location- Computational Methods

  8. Design Approach ParcPad ParcTab Liveboard • New artifact • Used in everyday life • Types • Liveboard • Large ones used as shared display surfaces • Pad • Near megabit wireless communication bandwidth • Always ran XWindows • Tab • Power is a major issue, cannot always change batteries • Used COTS Intel 8051 microcontroller • Small touch-sensitive display screen

  9. Hardware Issues • Low power • Reduce Power Consumption • Power = Gate Capacitance × Voltage × Clock Frequency • Wireless • Metric: Bits/sec/meter3 • Electromagnetic spectrum range • Power fall-off r6 • Pens • Casual use, no training, naturalness, simultaneous multiple use • PARC devised a new infrared pen

  10. Network Protocols • MACA (Multiple Access with Collision Avoidance) • Used to avoid “Hidden terminal” • Fairness • Same back-off parameter for all neighbor stations • NCTS(n) (Not Clear To Send) • Other network issues • Gb networks for real time data • Important for multimedia data • Mobility • Existing IP dose not support mobility • Virtual IP • Mobile IP

  11. Interaction Substrates • Different interaction area • Tab (small), liveboard (huge) • X-Window system • Designed for network • Does not provide mobility • To solve this problem, Jacobi developed new X-window toolkit • Different bandwidth • Vary from Kbps to Gbps • Use low bandwidth

  12. Applications • Locating people • Data acquired from: • Logins to workstations/terminals • An Active badge system • Useful for • Automatic call forwarding • Shared Drawing Tools • Shared draw • Data Representation • Tivili-Object based • Slate-Pixel based • UI Issues • How to handle multiple cursors? • Use gestures or not? • Use an ink based or character recognition model of pen input?

  13. Privacy of Location • Location information • Important for routing • Need to be protected • Solutions • Central DB of location • Privacy controls can be centralized • But one break-in there reveals all • Transmission of the location information to a central site • Centrality is unlikely to scale worldwide • Storing information about each person at that person’s PC • Programs must query the PC, and proceed through whatever security measures the user has chosen to install

  14. Computational Methods • Cache sharing problem • Classical distributed computing problem • Processing power > Link speed • Pages are often compressed • Compare online algorithm with offline algorithm • Offline algorithm is better than online

  15. Summary - Conclusion

  16. Conclusion • What is ubiquitous? • Issues of ubiquitous computing • Tab, Pad, Liveboard • Ubicomp is likely to provide a framework for interesting and productive work for many more years • Have much to learn about the details

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