September 13, 20051 Motivating Sensor Network Research: The Applications and Computer Science Issues Prabal Dutta and David Chu

September 13, 2005 1

Motivating Sensor Network Research:The Applications and Computer Science Issues

Prabal Dutta and David Chu


What Makes Good Application-Led Research?

Richard Sharp and Kasim Rehman


Perspectives

• “Applications are of course the whole point of ubiquitous computing”– Mark Weiser [Wei93]

• “We need to increase the applications deployed to books written ratio in sensor networks”– Deborah Estrin [Personal Communications]

• “In the future, increasing proportion of computer science research will be application-driven”– Eric Brewer and Mike Franklin [CS262A-Fa04]


Defining Application-Led Research

• Application-Led Research– Driven by domain problem– Evaluated by quantifying benefits brought to domain

• Technology-Led Research– Not necessarily motivated by potential domain benefits– Interesting or challenging from a technical perspective

• Research Goals Should (do you agree?)– Identify users’ problems and application requirements– Provide infrastructure developers with application

requirements– Validate technology and provides insights into its use


Selecting Applications

• Will this change the way people think?– If nothing changes after your research, what’s the point?

• Must make an impact on computer science– Just impacting biology or civil engineering is not enough– Starting from scratch can make this more difficult or easier

• If system building, what will you learn from it?– There must be an important question in there!

• Identify and attack “severe and persistent problems”

• Avoid trivial “proof-of-concept” research projects– Team up with domain experts when selecting problems– Make sure there’s a concept and it’s worth proving


Implementing Applications

• To start from scratch or not?– Benefits?

– Drawbacks?

• Is building reusable infrastructure worth it?– Research community values novelty over good engineering

– Research community doesn’t value implementation as research

– Do you agree?

• Reframe the question: What are your options? (Aside)– Your efforts can be directed structurally or strategically

• Structural: change the community so that it values infrastructure• Strategic: pick the right topic, and your work will be broadly used

(and well referenced)


Evaluating Applications

• Small, lab-scale evaluations– Useful: in the early stages of design– Insufficient: impossible to understand the impact of

• Environment on technology

• Technology on environment

• NEST FE Provides some good examples

• Applications are evaluated only against themselves– Self-evaluation is insufficient– Requires applications, infrastructure, and data to be

shared• Is this a good idea?

• Is it done in other fields?


Recommendations

• Choose applications carefully– Address severe persistent problems; avoid trivial ones

• Share technical infrastructure– Design reusable SW/HW; publicly release code

• Evaluate applications in realistic environments– Only way to investigate interactions between tech/env/users– “The real world is it’s own best model” – Rodney Brooks

• Perform comparative evaluations– Release data sets from field trials; allows other to analyze


Allen Newell’s Research Style


Allen Newell’s Research Style

• Good science responds to real problems– Don’t pick fantasy problems; there are too many real ones

• Good science is in the details– Takes the form of a working model– Includes detailed analysis or implemented models

• Good science makes a difference– Measure of contribution is in

• How it solves real problems

• Shapes the work of others


Some Computer Science Issues in Ubiquitous Computing

Mark Weiser


Are We There Yet?

• Hundreds of Tabs?

• Tens of Pads?

• One or two Boards?


Did Their Work Have Impact?

• Yes! Due to emphasis on computer science issues:

“The fruitfulness of ubiquitous computing for new computer science problems justified our belief in the…framework”

• Issues like– Hardware components

• Low power (P=C*V^2*f gives lots of degrees of freedom)• Wireless (custom radios (SS/FSK/EM-NF bits/sec/meter^3 metric)• Pens (how do you write on walls?)

– Network Protocols• Wireless media access (MACA: RTS/CTS)• Gigabit networks (lot’s of little devices create a lot of traffic)• Real-time protocols (IP telephony)• Mobile communications


Connecting the Physical World with Pervasive Networks

Deborah Estrin, David Culler, Kris Pister, Gaurav Sukhatme


Goals

• Goal: to measure the physical world– Across large spaces– Over long periods of time– Using multiple sensing modalities– In remote, and largely inaccessible locations

“The physical world is a partially observable, dynamic system, and the sensors and actuators are physical devices with inherent accuracy and precision limits.”


Challenges

• Immense scale of distributed systems elements– Vast numbers of devices– Fidelity

• Limited physical access– Embedded in the environment– Remote, expensive, or difficult to access– Wireless communications– Energy harvesting or very moderated energy consumption

• Extreme dynamics– Temperature, humidity, pressure, grass height, …– Passive vigilance to a flurry of activity in seconds


Challenge: Immense Scale

NEST FE: 557 Trio Nodes, Self-powered, self-maintaining, GPS ground truth, multiple subsets


Challenge: Limited Physical Access

Top endcap

O-rings

Cylindrical enclosure

Protective skirt

Top sensing surface:incident PAR and TSR

Battery

Mica2Dot

Bottom sensing surface:temperature, humidity,barometric pressure, reflected PAR & TSRBottom endcap

to appear Sensys 05

Redwoods


Challenge: Extreme Dynamics

• Border Control– Detect border crossing

– Classify target types and counts

• Convoy Protection– Detect roadside movement

– Classify behavior as anomalous

– Track dismount movements off-road

• Pipeline Protection– Detect trespassing

– Classify target types and counts

– Track movement in restricted area

ExScal


Discussion

Documents

September 13, 20051 Motivating Sensor Network Research: The Applications and Computer Science Issues Prabal Dutta and David Chu