Pervasive & Ubiquitous
Computing
Hao Chu (朱浩華)
Lecture #2
3/1/2004
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Reading list
• Still working on it
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Indoor localization
Embedding computing into (everyday) objects
Interactions
Ubiquitous healthcare
Security and privacy protection
Skip systems and sensor networks & shorten the
overview
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Project
• Project idea & scenario (week 5,
3/22/2005)
• Project proposal (week 9, 4/26/2005)
• Proposal progress (week 13, 5/24/2005)
• Final project presentation (week 16,
6/13/2005)
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Course Wiki
• Add your WhoIsWho
• Add paper review (next week)
• Select papers
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History
• Mark Weiser. "The Computer for the 21th Century."
Scientific American, September 1991.
• Mark Weiser. "Some computer science issues in
ubiquitous computing." Communications of the ACM,
36(7):75-85, July 1993.
• Mark Weiser, John S. Brown. "The Coming Age of Calm
Technology." 1996.
• M. Satyanarayanan. "Fundamental Challenges in Mobile
Computing." Fifteenth ACM Symposium on Principles of
Distributed Computing, May 1996.
• M. Satyanarayanan. "Pervasive Computing: Vision and
Challenges." IEEE Personal Communications, August,
2001.
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M. Weiser. “The Computer for the
21th Century", Scientific
American, September 1991.
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Two Key Points
• Ubiquitous computing = computing integrated
with physical environment
– Computing being everywhere, yet people do not take
notice of them
– Computing becoming disappearing and invisible
• Location and scale are important.
– Adapt their behavior intelligently without AI: call
forwarding, follow-me display, reminder, good
substitute for computer vision, etc.
– Scale suitable to different tasks (heterogeneous
systems and networks)
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Examples of Disappearing
Technologies
• Writing
• Electric Motors
• They are everywhere (embedding & hidden into
physical objects), yet invisible.
• When a technology matures, they disappear!
– Maturity = cheap, small, widely applicable, good
usability, …
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Why Good Technology Is Invisible?
• Good technology stays out of the way of task
– Like a good pencil stays out of the way of the writing
• Bad technology draws attention to itself:
– Like a broken, or skipping, or dull pencil
• Computers are mostly not invisible
– They dominate interaction with them.
• Ubicomp is about making computers invisible.
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Ubicomp vs. Virtual Reality
• Should we live in virtual computing world? Or
should computing come out and live in our
physical world?
• VR simulates physical world & puts people
inside virtual computing world.
• Ubicomp is about bringing computing to people’s
physical world.
– Computing Embed into everyday objects (intelligent
objects)
– Integrate with social activities (social computing)
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Ubicomp vs. Multimedia
• Multimedia grabs user attention for
entertainment purpose.
• Ubicomp reduces user distraction, allowing
people to focus on tasks.
– Alternative output display on periphery of user
attention: (ambient display)
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Ubicomp Components
• Computing embedded and enhancing physical
objects
• Ubicomp = sensors + processors + networking
sensors + SW systems & middleware
– Example: Intelligent Transportation System (foreview
mirror)
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PARC Ubicomp Work (1991)
• Focus on devices that
transmit & display information.
• Device scale targets different
tasks.
– Consider three sizes: tabs, pads,
boards.
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Tabs
• Inch-scale Ubicomp devices
– Post-It notes
• Carried around by a person
• Hundreds in a room
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Credit cards, ID cards
Remote controllers
Badges
Tags / Labels (RFID)
Locating system (tags as library catalogs)
Animate static physical objects (active calendar, active
map)
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Pads
• Foot-scale Ubicomp
devices
– A sheet of paper / tablet PC
• Tens in a room
– Like scrap papers that can
be grabbed and used
anywhere, no unique ID.
• Like windows in Apple
Macintosh, but can spread
them out on a real desk.
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Boards
• Yard-scale Ubicomp device
• One in a room
• White board with e-chalk
– Shared white board with remote participants
• Video screen
• Electronic Bookcases
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Hardware Challenges (1991)
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High resolution flat panel display (cheap)
High speed processor
High capability storage
High bandwidth wireless Network
Lower power consumption
How well do today’s HW technologies meet
these challenges?
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Software Challenges (1991)
• Dynamic configuration of HW/SW in ubicomp
environments (dynamic systems)
• Application migration across heterogeneous
ubicomp environments
• Transparent linking of wired and wireless
networks (heterogeneous networks)
• How well do today’s SW technologies meet
these challenges?
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Sal Scenario
• Proactively brew coffee
informed by alarm clock
• Electronic Trails of
neighbor coming and
going
• Automatic recording pen
• Paper display (e-ink)
• Email locates garbage
door opener (RFID &
object reminder)
• Window tells weather
(ambient display)
• Intelligent car navigation
(location-based services)
• Share location, tabs &
pads with Joe (CSCW)
• Gesture to project
blinking tab to projector
(multi-model UI)
• Memory augmentation on
meeting with Mary (lifelog)
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Privacy
• Hundreds and thousands of invisible computers
sensing and watching people
• Ubiquitous camera recording
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Is Weiser really Wise?
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What is the problem that he wants to solve?
What is his proposed solution?
Any problems with the proposed solution?
Invisibility & Intelligence vs. privacy
– RFID in supermarket
– Hidden security camera
• Invisible vs. transparent
– Diagnose problems
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M. Weiser. “Some computer
science issues in ubiquitous
computing.”Communications of
the ACM, 36(7):75-85, July 1993.
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Key Point
• Based on their PARC experiments with tabs,
pads, and boards, this paper tries to define
some ubicomp challenges and where ubicomp is
going.
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Ubicomp as Experimental CS
• Construct working prototype
• Evaluate working prototype in everyday use
• Find out real vs. imaginary issues
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Hardware Issues
• Power consumption: impossible to change
batteries to many ubicomp devices frequently.
• Balance of HW/SW feature: display, network,
processing, memory, storage capability,
multitasking, etc.
• Ease of expansion & modification (integration vs.
modular design)
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Network Issues
• Wireless Media Access (802.11, Bluetooth,
Cellular Networks)
• Quality of Services (RSVP, etc)
• Ubicomp devices changing network attachment
(Mobile IP)
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UI Issues
• Multi-modal UI
– Handprinting recognition
– Voice recognition
• Display migration (follow-me display)
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Application Issues
• “Applications are of course the whole point of
ubiquitous computing”.
• Locating people (active badges)
– Automated call forwarding
– Tracking down people for meeting
– Watching general activity in a building (feel in touch
with surrounding environments)
• Shared drawing in virtual meeting
– Scalability to 5000 peoples (multicast for bandwidth
efficiency)
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Location Privacy
• Centralized location database as one possible
solution, but not scalable, vulnerable to single
point of attack, one break-in reveals all.
• Move toward more distributed approach.
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Computational Method Issue
• Due to unpredictable network to ubicomp
devices, (file) caching can be used to improve
performance.
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Discussion
• Open ….
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M. Weiser, J. S. Brown. "The
Coming Age of Calm
Technology." 1996.
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Key Points
• Why the need for calm technology?
– Computers everywhere
– Pay attention in order to use them
– Information overloading
• Solution for design of ubicomp technology
– Place information in periphery of user attention
– But allow fast & easy moving to center
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Computing Trends
• These trends are results of computing getting
smaller, faster, and cheaper.
• Mainframe Era: many people sharing a
computer.
• PC Era: one computer per person
• Internet Era: (interconnecting PCs)
• Ubicomp Era:
– many computers (everyday objects) sharing one
person
– interconnecting everyday objects
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Calm Technology
• Calm and uncalm technology differs how to
engage our attention.
– Divide our attention into two parts: periphery and
center.
• Periphery is informing without overburdening
– While driving a car, center = roads and radio,
periphery = engine noise
• Calm technology can move easily & quickly
between periphery and center.
• Calm requires good design affordance (visual
clue to the function of an object)
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Three Signs of Calm Technology
• Move easily from center to periphery and
back
• Enhance “periphery reach” (more details in
the periphery)
– Video vs. voice conferencing
• Good information visualization
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Examples of Calm Technology
• Inner Office Windows
– Extend periphery to what are going on the hallway
– E.g., notice lunch gathering, meeting, but not
distracting to work
• In comparison to open cubicles with low
partitions
– Force too much to the center
– E.g., noises in the hallway can become distracting to
work
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Dangling String
• Represent bits flowing
over a wire through
motion and sound.
• The output is
(beautifully?) integrated
with our physical
environment.
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Discussion
• Is Ubicomp defined by the devices or user
experience?
• Imbed vs. Embed?
• Are inner office window and dangling string
really calm and relaxing?
• Does Calm give more or less information?
• This is related to ambient display research. UI
People know more about this research area?
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M. Satyanarayanan.
"Fundamental Challenges in
Mobile Computing", Fifteenth
ACM Symposium on Principles of
Distributed Computing, May 1996.
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Key Points
• What are fundamental challenges in mobile
computing (What is so special about mobile
computing)?
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Resource-limited mobile devices
Mobility is hazardous
Unpredictable wireless networks
Finite power source
• Adaptation is key to mobility.
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Evolution from Distributed Systems
to Mobile Computing
• What are fundamental differences between
Distributed Systems and Mobile Computing?
– Distributed systems = Applications running over
Computers Connected Over Network
– Mobile systems = Applications running over mobile
devices connected over wireless networks
– Mobile devices constraints: resource-limited, finite
power source, easy-to-lose (weak security)
– Wireless network constraints: unpredictability
bandwidth and frequent disconnections
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Adaptation is Key to Mobility
• Adapt applications to continuously changing
computing environment (due to mobility):
– Power, network bandwidth / availability, …
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Adaptation Strategies
• Need resource management at the system layer to
allocate resources to different applications.
• Need application level semantics, e.g., frame-rate,
resolution, etc.
• The best approach is to have both application and
system supports.
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Extended Client Server Model
• Traditional (thin) client (fat) server model in distributed
computing needed adjustments to address
unpredictable network, finite power, and performance.
• Extended client-server model (called smart client model)
places some server functionalities to client.
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Coda & Odyssey
• Coda supports application-transparent
adaptation.
– It is distributed file system (FS).
– It can cache/hoard some parts of FS on client.
– It can support disconnected operations from FS
cache.
• Odyssey supports application-aware adaptation.
– Adapt application quality/fidelity (e.g., video
framework, resolution) based on dynamic network
condition, power saving, and processing loads.
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Research Topics for Exploration
• Caching metrics (what to cache/hoard?)
• Caching coherence (Semantic callbacks and
validators)
• Algorithms for resource revocation
• Agility (靈敏) vs. stability
• (Global) Resource estimation from local
observations
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M. Satyanarayanan. “Pervasive
Computing: Vision and
Challenges”, IEEE Personal
Communications, August, 2001.
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Key Points
• What are fundamental challenges in
pervasive/ubicomp computing (What is so
special about pervasive computing)?
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Effective use of smart spaces
Invisibility
Localized Scalability
Masking Uneven Conditioning
• We will hear a distinguished talk from author
directly.
– http://www.cs.uiuc.edu/news/dls/distlectpst.html
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Discussion
• What exactly is proactivity? How does it differ
from adaptation?
• Is Ubicomp still about old technical issues ..
– Integrating different technologies, devices and
services.
– Resource discovery protocol
– Optimization (different parameters such as power)
– Adaptation (with environments)
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