Some Computer Science Issuesin Ubiquitous Computing

Presenter : Junghee-Han

Mark WeiserCommunications of the ACM, July 1993

What was Ubiquitous Computing in 1993 ? Hardware prototypes Issues of Ubiquitous Computing

Hardware components Network protocols Interaction Substrates Applications Privacy of location Computational Methods

Conclusion

Contents

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Very new to the field of Computer ScienceUbiquitous Computing was 1st defined by Mark Weiser at Xerox Palo Alto Research Center(PARC) in 1991

Three Waves of Computing Main Frame

• Many Person - One Computer Personal Computer

• One Person - One Computer Ubiquitous Computing

• One Person - Many Computer

Ubiquitous Computing in 1993

3 Ubiquitous Computing

Ubiquitous Computing is Next-generation computing environment Each person is interacting with hundreds of nearby

wirelessly interconnected computers Essentially invisible to user New kind of computers of all sizes and shapes will be

available to each person Ubiquitous Computing is Quite different from personal digital assistants Computers should be autonomous agents

The Challenge is To create a new kind of relationship of people to

computers

Ubiquitous Computing in 1993

4 Ubiquitous Computing

Virtual Reality puts people inside a com-

puter-generated world

Ubiquitous Computing forces the computer to live

out here in the world with people

VR vs. Ubiquitous Computing

5 Ubiquitous Computing

Hardware Prototypes

The physical world comes in all size and shapes

Three different sizes of devices Large-size: Liveboard Medium-size: Xpad Small-size: ParcTab

A pervasive part of everyday life With many active at all times

6 Ubiquitous Computing

Large-Size Prototype LiveBoard Main idea was to simulate a office whiteboard Order of 1 per office Xerox product

Hardware Prototypes

7 Ubiquitous Computing

Hardware Prototypes

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Medium-Size Prototype Xpad Main goal was to simulate a personal notebook Order of 10+ per person Design focus

• The right balance of features• The requirements

for particular features• Ease of expansion and modification

Ubiquitous Computing

Hardware Prototypes

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Small-Size Prototype ParcTab Information doorway Main goal was to simulate PostIts Order of 100+ per person Design Philosophy

• Put devices in everyday use Design Problem

• Size and Power Consumption

Ubiquitous Computing

To construct and deploy prototypes Need to readdress some of the well-worked areas of

existing Computer Science

Organization of a computer system Hardware components Network protocols Interaction substrates Applications Privacy of location Computational methods

The Computer Science of UbiComp

10 Ubiquitous Computing

Low power Work to reduce power rather than to increase per-

formance Wireless

Permits reuse of the same frequency again Permits transceivers that use low power

Infrared Pens Work over large area Need not touch the screen Operate from several feet awayThere is a need to balance

performance and power usage

Issues of Hardware Components

11 Ubiquitous Computing

Network Protocols Wireless media access

Use Multiple Access Collision Avoidance (MACA) For fairness

• Same back-off parameter for all neighbor stations

Real-time protocol To support multimedia applications

Mobility support Device in one region moves

other regions IP can’t solve this: Mobile IPEnabling media access whilecontinuously moving between spaces

12 Ubiquitous Computing

Interaction substrates Tabs Have a very small interaction area “Touch typing” that uses only a tiny area

Liveboards Using conventional pull-down or pop-up menus re-

quires walking across the room Location-independent interaction is need

X-window system User may move from device to device,

and want to bring windows along Window migration tools

Removing technical barriers between user and device

13 Ubiquitous Computing

Applications

The location of people Information about Location can be deduced from lo-

gins or collected from an active badge system Update the location database

Shared meeting tools Pen-based drawing on a surface Several users simultaneously operate independently

on different orsame pages

Location aware andallowing multiple users

14 Ubiquitous Computing

Privacy of Location

In cellular system Traveling pattern of cellular phone user can be de-

duced from the roaming data Much worse in ubiquitous computing

Preserving privacy of location Central DB of location information Store information at each person’s PC Short-term accumulation of location

informationTransmission and sharing of datamust be evaluated in a social context

15 Ubiquitous Computing

Computational Methods

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Optimal Cache Sharing Problem Optimal strategy for partitioning memory between

compressed and uncompressed pagesRequires methods to handle cachemisses over high latency mediums

Ubiquitous Computing

Conclusion

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Ubiquitous Computing is Making many computers available throughout the

physical Environment While making them effectively invisible to the userUbicomp seems likely to provide a framework For interesting and productive work For many more yearsHave much to learn aboutthe details

Ubiquitous Computing