Applications of Sensor Networks

1
Applications of Sensor Networks

• Chen, Weifeng
• Gong, Ying
• Liu, Xiaotao

2
Outline

• Why sensor nets?
• Advantages
• Applications
• Classifications of sensor nets
• Challenging issues
• Common constraints
• Application-specific constraints
• Discussions

3
Outline

• Why sensor nets?
• Advantages
• Applications
• Classifications of sensor nets
• Challenging issues
• Common constraints
• Application-specific constraints
• Discussions

4
Advantages of Sensor Nets

• Intimate connection with its immediate
  environment.

5
Advantages of Sensor Nets (cont.)

• Intimate connection with its immediate
  environment.
• No disturbance to environment, animals, plants,
  etc.

6
Advantages of Sensor Nets (cont.)

• Intimate connection with its immediate
  environment.
• No disturbance to environment, animals, plants,
  etc.
• Avoid unsafe or unwise repeated field studies.

7
Advantages of Sensor Nets (cont.)

• Intimate connection with its immediate
  environment.
• No disturbance to environment, animals, plants,
  etc.
• Avoid unsafe or unwise repeated
• field studies.
• Economical method for long-term data collection
• One deployment, multiple utilizations

8
Applications of Sensor Nets

• Habitat monitoring
• Environmental observation and forecasting
  systems Columbia River Estuary
• Smart Dust
• Biomedical sensors

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Habitat Monitoring

• Petrel habitat on Great Duck Island in Maine.
• Questions to answer
• Usage pattern of nesting burrows over the 24-72
  hour cycle
• Changes in the burrow and surface environmental
  parameters
• Differences in the micro-environments with and
  without large numbers of nesting petrels
• Primitive requirement no human disturbance.

10
Approach to habitat monitoring
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Estuarine Environmental Observation and
Forecasting System

• Observation and forecasting system for the
  Columbia River Estuary

12
CORIE Approach

• Real-time observations
• Estuarine and offshore stations
• Numerical modeling
• Produce forecast, hindcast of circulation
• Virtualization application
• Vessel survey, navigation
• fishing, etc

13
Smart Dust Mote

• Tiny light-communication

14
Military Applications of Smart Dust
15
Biomedical Sensors

• Sensors help to create vision

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Outline

• Why sensor nets?
• Advantages
• Applications
• Classifications of sensor nets
• Challenging issues
• Common constraints
• Application-specific constraints
• Discussions

17
Classifications of Sensor Nets

• Sensor position
• Static (Habitat, CORIE, Biomedical)
• Mobile (Smart Dust, Biomedical)
• Goal-driven
• Monitoring Real-time/Not-real-time (Habitat,
  Smart Dust)
• Forecasting (CORIE)
• Function substitution (Biomedical)
• Communication medium
• Radio Frequency (Habitat, CORIE, Biomedical)
• Light (Smart Dust)

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Outline

• Why sensor nets?
• Advantages
• Applications
• Classifications of sensor nets
• Challenging issues
• Common constraints
• Application-specific constraints
• Discussions

19
Common Challenging Issues

• Limited computation and data storage
• Low power consumption
• Wireless communication
• Medium, ad hoc vs. infrastructure, topology and
  routing
• Data-related issues
• Continuous operation
• Inaccessibility network adjustment and
  retasking
• Robustness and fault tolerance

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Application-specific Constraints

• Material Constraints
• Bio-Compatibility
• Inconspicuous
• Imitative to environment
• Detect-proof e.g. stealth flight
• Secure Data Communications
• Regulatory Requirements such as FDA

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Limited Computation and Data Storage

• Sensor design
• Multi-objective sensors and single (a
  few)-objective sensors.
• Cooperation among sensors
• Data aggregation and interpretation

22
Low Power Consumption

• Low power functional components
• Power-manageable components
• Several functional state (low state-transition
  overhead)
• Deep-sleep, Sleep, On
• Provide different QoS with different power
  consumption.
• Power Management
• Power measurement
• Power budget allocation
• Control transitions between different power
  states.

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Wireless Communication

• Communication mediums
• Radio Frequency Habitat monitoring, Biomedical
  sensors and CORIE estuarine observation
• Light (active and passive) Smart Dust
• Ad hoc versus infrastructure modes
• Topology
• Routing

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Smart Dust Passive Transmitters
UnmodulatedInterrogation
Lens
Photo-
detector
Downlink
Laser
Downlink
DataIn
DataOut
Uplink
Signal Selection
and Processing
DataIn
CCD
Corner-Cube
Image
Lens
Retroreflector
ModulatedReflected
Sensor
Array
DustMote
Uplink
Uplink
...
Data
Data
Asymmetric Link assumed high power laser emit
from BS, with larger scale imaging array
Out
Out
N
1
Base-StationTransceiver
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Smart Dust Active Transmitter (cont.)

• BS uses CCD or CMOS camera (operate at up to 1
  Mbps)
• Using multi-hop routing, not all dust motes need
  LoS to BS

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Smart Dust Active Transmitter
Two-axis beam steering assembly
Active dust mote transmitter

• Beams have divergence ltlt 1º
• Steerable over a full hemisphere

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Ad hoc vs. Infrastructure Modes

• Sensor - Sensor communication
• Short distance
• Ad hoc
• Sensor - Base station communication
• Long distance sensor to base station
  communication
• Infrastructure

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Wireless Communication Topology

• Fixed topology
• Tree based
• Cluster based
• Dynamic topology - mobility
• Ad hoc
• Infrastructure
• Mixed

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Research on Fixed Topologies

• Vary of neighbors
• Trade-offs exist
• Number of hops
• Number of receivers
• Amount of contention
• Evaluate power usage
• Test power-aware routing
• Results
• Power-aware routing reduces power usage
• 3D is better than 2D

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Research on Fixed Topologies (cont.)
Cluster-based
Tree-based
Cluster-based approach provides better
energy-efficiency than the tree-based approach.
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Wireless Communication Routing

• Route discovery
• Redundancy discovery
• Failure detection and recovery
• Distributed and localized
• Avoid single-point failure
• Avoid bottleneck
• Energy-efficient

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Energy-Efficient Routing Protocol

• Routing protocol metrics
• Traditional packet loss, routing message
  overhead, routing length
• New metric energy consumption ,
  ?24
• Imagine

M
5
5
S
T
9
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Data-related issues

• Trade-off between latency and energy
• Real-time
• Periodic
• Data representation
• Raw/Compressed data
• Sampling Value Absolute/Relative
• Error calibration
• No access to real values
• Inferred from other sensors

34
Continuous Operation

• Long-term data collection
• Renewable power source.
• Solar energy
• Mechanical vibrations
• Radio-Frequency inductance
• Infrared inductance

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Inaccessibility

• Sensor location
• Embedded environment
• Avoid disturbance to sensing objects
• Network adjustment
• Network retasking

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Robustness and Fault Tolerance

• Self-adaptive sensors
• Adapted to the environment changes.
• Adapted to the power change.
• Distributed network
• Each sensor operate autonomously from neighbors.
• Overlapped services area.
• No single point of failure.
• Health and status monitoring
• E.g. reporting power along data transmission

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Outline

• Why sensor nets?
• Advantages
• Applications
• Classifications of sensor nets
• Challenging issues
• Common constraints
• Application-specific constraints
• Discussions

38
Discussions

• Unique solution to all applications exists?
• Most important considerations in designing
• Cost?
• Resource allocation?
• Manageability?
• Timeliness?
• Retasking?
• Scalability?
• Millions of sensor nodes?
• Next generation sensor nets?

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The End

• Thank you