Wireless sensor networks Overview

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Wireless sensor networks Overview applications

• Murat Demirbas

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Wireless sensor networks

• A sensor node (mote)
• 8K RAM, 4Mhz processor
• magnetism, heat, sound, vibration, infrared
• wireless (radio broadcast) communication up to
  100 feet
• costs 10 (right now costs 200)?

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Outline

• Vision
• Ubiquitous pervasive proactive computing
• Design space
• Challenges
• Applications
• Ecology monitoring
• Precision agriculture
• Asset management
• Military surveillance

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Ubiquitous computing

• Mark Weiser, PARC, 1991
• The most profound technologies are those that
  disappear
• E.g., Writing does not require active attention,
  but the information to be conveyed is ready for
  use at a glance (Periphery / calm technology)?
• We should not be required to live in computers
  world (OS, virtual reality), computers should
  become invisible and ubiquitous (disappear in
  background) in our physical world
• Already computers in light switches, thermostats,
  stereos and ovens help to activate the world
• For such a technology, localization scalability
  are critical
• Location-aware devices
• Wireless communication
• Micro-kernel OS
• Distributed computing

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Ubiquitous computing

• Ubiquitous PC
• Tab post-it sized e.g., badge, shrink/store
  window on a tab
• Pad A4/letter sized e.g., scrap computer, edit
  each window on a pad
• Board yard sized e.g., long-distance meetings,
  bulletin boards
• Ubiquitous computers to overcome information
  overload
• There is more information available at our
  fingertips during a walk in the woods than in any
  computer system, yet people find a walk among
  trees relaxing and computers frustrating.
  Machines that fit the human environment, instead
  of forcing humans to enter theirs, will make
  using a computer as refreshing as taking a walk
  in the woods.

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iComp
Ubiquitous Computing Lab _at_ Furnas 210
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Proactive computing

• David Tennenhouse, Intel VP, 2000
• Moving from human-centered to human-supervised
  computing
• 150 million PCs versus 8 billion embedded
  computers
• Only 2 of computers are PCs
• Getting physical
• embedded computers
• Getting real
• real-time, fast responses from computers need to
  be arbitrated
• Getting out
• human above the loop (hidden Markov models)?
• Reinventing computer science

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Next century challenges Scalable coordination in
sensor networks
Embedded
Networked
Exploitcollaborative Sensing, action
Control system w/ Small form factor Untethered
nodes
Sensing
Tightly coupled to physical world

• Distributed local algorithms are needed for
  scalability!

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New Class of Computing
log (people per computer)?
streaming information to/from physical world
year
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Technology Push

• CMOS miniaturization
• Micro-sensors (MEMS, Materials, Circuits)?
• acceleration, vibration, gyroscope, tilt,
  magnetic, heat, motion, pressure, temp, light,
  moisture, humidity, barometric
• chemical (CO, CO2, radon), biological,
  microradar, ...
• actuators too (mirrors, motors, smart surfaces,
  micro-robots)?
• Communication
• short range, low bit-rate, CMOS radios
• Power
• batteries remain primary storage, fuel cells 10x
• solar, vibration, flow

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Design space

• Deployment (random vs manual)?
• Mobility (static vs mobile occasional vs
  continuous active vs passive)?
• Cost, Size, Resources (brick vs matchbox vs
  grain)?
• Heterogeneity (homogenous vs heterogeneous)?
• Communication modality (radio vs light vs
  inductive)?
• Infrastructure (ad hoc vs infrastructure)?

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Design space

• Network topology (single-hop vs multihop)?
• Coverage (sparse vs dense)?
• Connectivity (connected vs intermittent vs
  sporadic)?
• Network size (10 vs 100 vs 1000 vs 10,000 vs
  100,000)?
• Lifetime (day vs month vs year vs decade)?
• QOS requirements (none vs real-time)?

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Challenges in sensor networks

• Energy constraint
• Unreliable communication
• Unreliable sensors
• Ad hoc deployment
• Large scale networks
• Limited computation power
• Distributed execution

• Nodes are battery powered
• Radio broadcast, limited bandwidth, bursty
  traffic
• False positives
• Pre-configuration inapplicable
• Algorithms should scale well
• Centralized algorithms inapplicable
• Difficult to debug get it right

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Assignment 1

• Present in class one WSN or smartphone
  application
• Outline the overall function of the WSN or
  smartphone in this application. What is the
  improvement it offers?
• Specify the design parameters and challenges for
  the proposed system
• Enumerate the system requirements and challenges
• Time for your presentation should be around 7
  minutes

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References for assignment

1. Great Duck island
2. Agricultural applications
3. Analysis of a habitat monitoring application
4. NASA SensorWeb
5. Meteorology and Hydrology in Yosemite
6. Monitoring redwoods
7. ZebraNet
8. Virtual fences
9. Active visitor guidance system
10. UVA flock control

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References for assignment

1. Counter-sniper system
2. Self-healing land mines
3. Damage detection in civil structures
4. Smart-tag based data dissemination
5. Continuous medical monitoring
6. Elder care
7. Aware home
8. Smart kindergarten
9. Media production
10. Factory floor monitoring

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Assignment 2

• Summarize one of the following
• Some computer science issues in ubiquitous
  computing (Weiser)?
• Proactive computing (Tennenhouse)?
• Next century challenges (Estrin.)?

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Outline

• Vision
• Ubiquitous pervasive proactive computing
• Design space
• Challenges
• Applications
• Ecology monitoring
• Precision agriculture
• Asset management
• Military surveillance

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WSN applications

• a new "scope" to a scientific endeavor
• a new approach to an engineering problem
• a new capability to a computing environment
• a new form of entertainment
• a new product opportunity

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Ecology monitoring

• Monitoring nesting behavior of birds
• Great Ducks experiment
• Detecting forest fires
• Detecting chemical or biological attacks
• Monitoring Redwood trees

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Dense Self-Organized Multihop Network
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10m
20m
34m
30m
36m
2003, unpublished
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Precision agriculture

• Wireless sensor networks can be placed on farm
  lands to monitor temperature, humidity,
  fertilizer and pesticide levels
• Pesticide and fertilizer can only be applied when
  and where required
• Pesticide and fertilizer per one acre costs 20
• Considering 100,000 acres savings of 2 million
  possible

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Equipment Health Monitoring in Semiconductor Fab

• Equipment failures in production fabs is very
  costly
• Predict and perform preemptive maintenance
• Typical fab has 5,000 vibration sensors
• Pumps, scrubbers,
• Electricians collect data by hand few times a
  year
• Sample 10s kilohertz, high precision, few
  seconds

Fab Equipment
Intranet
Intranet isolation
Ad Hoc Mote Network
Root Node
802.11 Mesh
Mote Vibration Sensors
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Project ExScal Concept of operation
Put tripwires anywherein deserts, other areas
where physical terrain does not constrain troop
or vehicle movementto detect, classify track
intruders
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Envisioned ExScal customer application
Convoy protection
Detect anomalous activity along roadside
Hide Site
IED
Border control
Canopy precludes aerial techniques
Gas pipeline
Rain forest mountains water environmental
challenges
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ExScal summary

• Application has tight constraints of event
  detection scenarios long life but still low
  latency, high accuracy over large perimeter area
• Demonstrated in December 2004 in Florida
• Deployment area 1,260m x 288m
• 1000 XSMs, the largest WSN
• 200 XSSs, the largest 802.11b ad hoc network

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Line in the sand project

• Thick line allows detection classification as
  intruders enter the protected region also allows
  fine grain intruder localization
• Grid of thin lines allows bounded uncertainty
  tracking

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ExScal sample scenarios

• Intruding person walks through thick line
• (pir) detection, classification, and fine-grain
  localization
• Intruding vehicle enters perimeter and crosses
  thick line
• (acoustic) detection, classification, and
  fine-grain localization
• Person/ATV traverses through the lines
• coarse-grain tracking
• Management operations to control signal chains,
  change parameters, and programs dynamically
  query status and execute commands