Pervasive & Ubiquitous Computing Hao Chu (朱浩華) Lecture #2 2/23/2004

Administrative Announcements Course homepage is up. http://www.csie.ntu.edu.tw/~hchu/ubicomp_course/ubicomp_course.htm Reading list, project overview, project ideas, … Course WIKI page is up. “How to use WIKI?” by James

Vision and Challenges M. Weiser, “The Computer for the 21th Century", Scientific American, September 1991. M. Weiser, “Some Computer Science Issues in Ubiquitous Computing”, Communications of the ACM, 36(7):75-85, July 1993. M. Weiser, J. 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.

M. Weiser. “The Computer for the 21th Century", Scientific American, September 1991.

Two Key Points Ubiquitous computing is about computing so well integrated with our physical environment such that people fail to take notice of them. Computing being everywhere, yet fading into the background Computing becoming disappearing and invisible Location and scale are important issues. Adapt their behavior intelligentlly without complex AI Scale suitable to different tasks

Examples of Disappearing Technologies Writing Electric Motors Micro-controllers in CEs They are everywhere (embedding & hidden into physical objects), yet invisible. When a technology matures, they disappear! Maturity = cheap, small, widely applicable, good usability, … Writing is everywhere (on street signs, shop signs, drinks, CDs, etc). Yet, using writing does not require active attention to writing technology (e.g., how to make ink, how to use a pen, etc.)

Why Good Technology Is Invisible? “Invisible” stays out of the way of task Like a good pencil stays out of the way of the writing Like a good car stays out of the way of the driving Bad technology draws attention to itself: Like a broken, or skipping, or dull pencil Like a car that needs frequent tune-ups Computers are mostly not invisible They dominate interaction with them. Ubicomp is about making computers invisible. Computers are mostly not invisible. Playing Music.

Ubicomp vs. Virtual Reality Should we live in virtual computing world? Or should computing come out and live in our physical world? VR is about simulating physical world & putting people inside virtual computing world. Limited applications & activities Ubicomp is about bringing computing to people’s physical world. Integrating with everyday objects and activities Computer generates virtual world. Users wear googles or gloves. People manipulate virtual objects in virtual computing world. People manipulate physical objects enhanced by computers. VR cannot deal with desks, offices, people not wearing googles, take a trip, walk in the woods,

Ubicomp vs. Multimedia Multimedia grabs user attention for entertainment purpose. Ubicomp reduces user distraction, allowing people to focus on tasks.

Intelligence Computing embedded and enhancing physical objects Achieve intelligence through interconnection of physical objects Wall talking to heating or projector Achieve intelligence through location awareness (without AI) Automated call forwarding, lighting control Interconnection : smart sensor wall -> control heating and lighting smart medicine cabinet -> refrigerator Context awareness: location aware: know which room I am in, telephone should ring in the room I am in (rather than anywhere) scale aware

PARC Ubicomp Work (1991) Focus on devices that transmit & display information. Device scale targets different tasks. Consider three sizes: tabs, pads, boards.

Tabs Inch-scale Ubicomp devices Carried around by a person Post-It notes Carried around by a person Hundreds in a room Credit cards, ID cards Remote controllers Badges Tags / Labels (RFID) Locating system (tags as library catalogs) Animate static physical objects (active calendar, active map) Tracking people / objects, Door greets people by name, automated call forwarding,

Pads Foot-scale Ubicomp devices Tens in a room 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.

Boards Yard-scale Ubicomp device One in a room White board with e-chalk Shared white board with remote participants Video screen Electronic Bookcases

Hardware Challenges (1991) 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?

Software Challenges (1991) Dynamic configuration of HW/SW in ubicomp environments (device mobility) Application migration across heterogeneous ubicomp environments (user mobility) Transparent linking of wired and wireless networks Tiny range wireless, long range wireless, high speed wired How well do today’s SW technologies meet these challenges?

Sal Scenario Proactively brew coffee Electronic Trails of neighbor coming and going (Privacy issue) Automatic recording pen Email locating garbage door opener Window tells weather Share location info with Joe (Privacy Issue) Share tabs/pads with Joe (Miniaturization) Gesture to project blinking tab to projector. Memory augmentation on meeting with Mary.

Privacy Issue Hundreds and thousands of invisible computers sensing and watching people A bit scaring?

Misc Ubicomp as a Savor to Healthy Social Interaction? People don’t have to hole up in windowless offices before computer screens all days. Ubicomp as relaxing as “talking a walk in the woods”

Discussion Tradeoff between intelligence and privacy Tradeoff between invisibility and privacy What are killer ubicomp applications? Think about interesting scenarios for interconnecting home appliances AI & ubicomp? Should computing stay out of the physical world? Human dependency on computing Environmental impacts Social impacts

M. Weiser. “Some computer science issues in ubiquitous computing M. Weiser. “Some computer science issues in ubiquitous computing.”Communications of the ACM, 36(7):75-85, July 1993.

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.

Ubicomp as Experimental CS Construct working prototype Evaluate working prototype in everyday use. Importance of “working prototype”

Hardware Prototype Issues Power consumption: impossible to change batteries to many ubicomp devices frequently. Balance of HW/SW feature: display, network, processing, memory, storage capability, multitasking, QoS, etc. Ease of expansion & modification (integration vs. modular design)

Hardware Issues Low-power computing High-speed wireless bandwidth (802.11g 54 Mbps) Pens for very large display

Network Issues Wireless Media Access (802.11, Bluetooth, Cellular Networks) Quality of Services (RSVP, etc) Ubicomp devices changing network attachment (Mobile IP)

Interaction Substrate Issues Interaction substrates are UI software for pens and screens. Handprinting recognition Voice recognition Display migration (follow-me display)

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)

Location Privacy Centralized location database as one possible solution, but not scalable, single point of attack, one break-in reveals all. Move toward more distributed approach.

Computational Method Issue Due to unpredictable network to ubicomp devices, (file) caching can be used to improve performance.

Discussion Open ….

M. Weiser, J. S. Brown. "The Coming Age of Calm Technology." 1996.

Key Points The computing trends is moving toward many (hundreds of) computers sharing each of us. Since computers are everywhere, they better stay out of our ways. Weiser called it Calm technology. A proposed solution (Calm technology) is to place most information in periphery of our attention, but allow fast & easy moving to center of our attention. What is like using five computers running different applications at the same time? How about hundreds? If they all demand our attention, they become overwhelming. Information overloading Another way to look at it is that while computing resources are becoming more abundant, human capability to process information remains fairly static. The most scare resource is user attention. Calm technology is about how to reduce user attention demanded by ubicomp.

Computing Trends These trends are results of computing getting smaller, faster, and cheapers. 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

Ubicomp Era Cheap “Thin servers” in every household appliances. Average home appliances (Microwaves, TV, DVD players, etc.) have embedded processors, but they are not Ubicomp devices, because They are not networked. They are not connected to the Internet. Alarm clock can find out correct time after power failure. Microwave downloads new recipe. Vending machines can order themselves when they run out of items. Kid toys are refreshed with new music or vocabularies.

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 E.g., driving a car, center = roads and radio, periphery = engine noise Calm technology can move easily & quickly between periphery and center.

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

Dangling String Represent bits flowing over a wire through motion and sound. The output is (beautifully?) integrated with our physical environment.

Discussion Is Ubicomp defined by the devices or user experience? 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?

M. Satyanarayanan. "Fundamental Challenges in Mobile Computing", Fifteenth ACM Symposium on Principles of Distributed Computing, May 1996.

Key Points What are fundamental challenges in mobile computing (What is so special about mobile computing)? Resource-limited mobile devices Mobility is hazardous Unpredictable wireless networks Finite power source Adaptation is key to mobility.

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

Adaptation is Key to Mobility Adapt applications to continuously changing computing environment (due to mobility): Power, network bandwidth / availability, …

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.

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.

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.

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 (Analysis of adaptation) (Global) Resource estimation from local observations

M. Satyanarayanan. “Pervasive Computing: Vision and Challenges”, IEEE Personal Communications, August, 2001.

Key Points What are fundamental challenges in pervasive/ubicomp computing (What is so special about pervasive computing)? 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

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) Anticipation vs. understanding user intent