Introduction To Wireless Sensor Networks

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Introduction ToWireless Sensor Networks
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Wireless Sensor Networks

• A wireless sensor network is a collection of
  nodes organized into a cooperative network. Each
  node consists of processing capability may
  contain multiple types of memory have an RF
  transceiver, have a power source (e.g., batteries
  and solar cells), and accommodate various
  sensors.

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Wireless Sensor Networks
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Communication Network

• A communication network is composed of nodes,
  each of which has computing power and can
  transmit and receive messages over communication
  links, wireless or cabled.

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Basic Network Topologies

• Star Topology
• Ring Topology
• Bus Topology
• Tree Topology
• Fully Connected Networks
• Mesh Networks

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Star Topology

• All nodes of the star topology are connected to a
  single hub node. The hub requires greater message
  handling, routing, and decision-making
  capabilities than the other nodes. If a
  communication link is cut, it only affects one
  node. However, if the hub is incapacitated the
  network is destroyed.

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Ring Topology

• In the ring topology all nodes perform the same
  function and there is no leader node. Messages
  generally travel around the ring in a single
  direction.
• However, if the ring is cut, all communication is
  lost.

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Bus Topology

• In the bus topology, messages are broadcast on
  the bus to all nodes. Each node checks the
  destination address in the message header, and
  processes the messages addressed to it.

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Tree Topology

• In Tree Topology there will be a root node and
  the root node has two branches. Each branch may
  again contains branches and so on.

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Fully-connected Network

• In a fully connected Network when additional
  nodes are added, the number of links increases
  exponentially.

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Mesh Network

• Mesh networks are regularly distributed networks
  that generally allow transmission only to a
  nodes nearest neighbors. The nodes in these
  networks are generally identical.

Mesh nets can be good models for large-scale
networks of wireless sensors that are distributed
over a geographic region.
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Communication Network
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• A single network may consist of several
  interconnected subnets of different topologies.
  Networks are further classified as Local Area
  Networks (LAN), e.g. inside one building, or Wide
  Area Networks (WAN), e.g. between buildings.

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Wireless Sensor Networks

• 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
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• The development of wireless sensor networks was
  originally motivated by military applications
  such as battlefield surveillance. However,
  wireless sensor networks are now used in many
  civilian application areas, including environment
  and habitat monitoring, healthcare applications,
  home automation, and traffic control.

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Sensor Node

• Networks of typically small, battery-powered,
  wireless devices.
• On-board processing,
• Communication, and
• Sensing capabilities.

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Sensor Node
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• In addition to one or more sensors, each node in
  a sensor network is typically equipped with a
  radio transceiver or other wireless
  communications device, a small microcontroller,
  and an energy source, usually a battery.

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Sensor Node
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Sensor Node
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Sensor Network
Server
Sensor field
Gateway
Internet
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Computer Revolution
MICAZ Mote (2005)
Original IBM PC (1981)
4 MHz
4.77 MHz
128 KB RAM
16-256 KB RAM
512 KB Flash
160 KB Floppies
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6K (today)
14 mW
64 W
0.5 oz, 2.25 x 1.25 x 0.25 inch
25 lb, 19.5 x 5.5 x 16 inch
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Sensor Network
Server
Watershed
Sensor field
Gateway
Internet
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Network Model for WSN

• A wireless sensor network consists of hundreds or
  thousands of low cost nodes which could either
  have a fixed location or randomly deployed to
  monitor the environment. The flowing of data ends
  at special nodes called base stations (sometimes
  they are also referred to as sinks).

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Network Model for WSN
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• A base station links the sensor network to
  another network (like a gateway) to disseminate
  the data sensed for further processing. Base
  stations have enhanced capabilities over simple
  sensor nodes since they must do complex data
  processing.

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Network Model for WSN
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• This justifies the fact that bases stations have
  workstation/laptop class processors, and of
  course enough memory, energy, storage and
  computational power to perform their tasks well.

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Usage of Sensor Networks

• Environmental Observation
• Sensor networks can be used to monitor
  environmental changes. An example could be water
  pollution detection in a lake that is located
  near a factory that uses chemical substances.
  Sensor nodes could be randomly deployed in
  unknown and hostile areas and relay the exact
  origin of a pollutant. Other examples include
  forest fire detection, air pollution and rainfall
  observation in agriculture.

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Usage of Sensor Networks
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• Military Monitoring
• Military uses sensor networks for battlefield
  surveillance sensors could monitor vehicular
  traffic, track the position of the enemy.

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Usage of Sensor Networks
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• Building Monitoring
• Sensors can also be used in large buildings or
  factories monitoring climate changes. Thermostats
  and temperature sensor nodes are deployed all
  over the buildings area. In addition, sensors
  could be used to monitor vibration that could
  damage the structure of a building.

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Usage of Sensor Networks
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• Healthcare
• Sensors can be used in biomedical applications to
  improve the quality of the provided care. Sensors
  are implanted in the human body to monitor
  medical problems like cancer and help patients
  maintain their health.

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• T h a n k Y o u