Wireless Sensor Network

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NetSim v9
TM
Network Simulation/Emulation Platform
Wireless Sensor Networks
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Wireless Sensor Network

• A wireless sensor network (WSN) is a wireless
  network consisting of spatially distributed
  autonomous devices using sensors to cooperatively
  monitor physical or environmental conditions,
  such as temperature, sound, vibration, pressure,
  motion or pollutants, at different locations.

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Wireless Sensor Networks

• Formed by hundreds or thousands of sensors that
  communicate with each other and pass data along
  from one to another
• Research done in this area focus mostly on
  reducing power consumption and battery life
  extension of sensors.

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A world of sensors
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Introduction to WSN / IEEE 802.15.4 WR-PAN

• 802.15.4 standard specifies the PHY and MAC layer
  for low rate personal area networks
• Ideal for communication between sensors because
  this standard
• Focused on low-cost low-power communication
  between devices
• Can work no underlying infrastructure (no
  routers, switches, base stations etc)
• Approx 10m coverage range with transfer rate of
  250Kbps
• Collision avoidance through CSMA/CA
• Frequencies
• 868 - 915 MHz
• 2.4 GHz ISM band and free worldwide

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Components of WSN in NetSim

• Sink node
• The principal controller in WSN
• Sensors send the sensed data to the sink
• Sensor
• - An abstract entity that can sense any physical
  phenomena such as temperature, pressure,
  light, etc.
• Agent
• - An abstraction for the physical phenomenon
  being sensed
• Any WSN has two components, the sensing part and
  the network communication part. NetSim is
  agnostic to the sensing part and only simulates
  the network communication

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Deployment
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IEEE 802.15.4 operational modes
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SuperFrame Structure
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SuperFrame Contd..
The structure of a superframe is defined by two
parameters macBeaconOrder (BO)
macSuperframeOrder (SO)
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• macBeaconOrder (BO) this attribute describes the
  interval at which the coordinator must transmit
  beacon frames. The value of the macBeaconOrder
  and the Beacon Interval (BI) are related as
  follows
• macSuperframeOrder (SO) this attributes
  describes the length of the active portion of the
  superframe, which includes the beacon frame. The
  value of the macSuperframeOrder and the
  Superframe Duration

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Beacon Enabled Mode

• If SO BO ?SD BIHence the superframe is
  always active.(no Inactive Period)
• According to the IEEE standard, if SOBO 15 ,
  then the superframe shall not exist and the
  network will operate in the non beacon-enabled
  mode.

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CSMA/CA Algorithm
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Data Link Layer Parameters
Parameter Standard Name Standard Value
Beacon Order BO 0 to 15
SuperFrame Order SO 0 to 15
Base SuperFrame Duration aBaseSuperframeDuration 15.36 milliseconds
Min Backoff Exponent macMinBE 3
Max Backoff Exponent aMaxBE 5
Max Frame Retries aMaxframeRetries 3
Max CSMA Backoffs macMaxCSMABackoffs 4
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PHY Parameters
Parameter Standard Value
Frequency Band 2.4 GHz
Chip Rate 2000 McPS
Symbol Rate 62.5 kSymbolsPS
Modulation Technique O-QPSK
Unit Backoff Time 20 Symbols
Turn Around Time 12 Symbols
Transmitter Power 100 mW
Sensor Range 100 m
Receiver Sensitivity -85 dbm
ED Threshold -95 dbm
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Power Model and Energy Harvesting in WSN

• Wireless Sensor nodes are designed to operate in
  very low data rate
• The sensor is in sleep mode most of the time
• Perform sensing and communication when needed
• Moderate power consumption in active mode and
  very low power consumption in sleep mode
• Improve lifetime of the network

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Power Model Metrics
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References

• Specification-based Intrusion Detection for Home
  Area Networks in Smart Grids
• Paria Jokar, Hasen Nicanfar, Victor C.M. Leung
  Department of Electrical and Computer Engineering
  The University of British Columbia
• ZigBee for Building Control Wireless Sensor
  Networks
• Fabio L. Zucatto1,2, Clecio A. Biscassi2
  Ferdinando Monsignore2, Francis Fidélix2, Samuel
  Coutinho2, and Mônica L. Rocha1
• ZigBee Based Wireless Sensor Networks and Its
  Applications in Industrial
• Shizhuang Lin1, Jingyu Liu2 and Yanjun Fang3
  Department of Automation, Wuhan University