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Elec6076 wireless sensor networks

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Elec6076 wireless sensor networks

  1. 1. Nadège Barrage - [email_address] ELEC6076
  2. 2. <ul><li>Definition </li></ul><ul><li>Network topologies </li></ul><ul><li>Standards </li></ul><ul><li>Applications </li></ul><ul><li>Conclusion </li></ul>Nadège Barrage – ELEC6076 – Wireless Sensor Networks
  3. 3. A wireless sensor network (WSN) = various wireless nodes communicating with base stations via radio link. It is an ad-hoc network : nodes act as forwarder, relaying data to a base station. Nadège Barrage – ELEC6076 – Wireless Sensor Networks
  4. 4. <ul><li>Each node is equipped with: </li></ul><ul><li>One or two sensors </li></ul><ul><li>A wireless commu-nications device </li></ul><ul><li>A small micro-controller </li></ul><ul><li>An energy source </li></ul>The sensors can measure various conditions: temperature, sound, vibration, pressure, motion, pollutants… Nadège Barrage – ELEC6076 – Wireless Sensor Networks
  5. 5. <ul><li>Main functions of the microcontroller: </li></ul><ul><li>Managing data collection from the sensors </li></ul><ul><li>Performing power management functions </li></ul><ul><li>Interfacing the sensor data to the physical layer </li></ul><ul><li>Managing the radio network protocol </li></ul><ul><li>Nodes are really cheap. Their interface and their components are very basic, so they don’t need a lot of resources (which is not the case for base stations). </li></ul>Nadège Barrage – ELEC6076 – Wireless Sensor Networks
  6. 6. <ul><li>Star Network: </li></ul><ul><li>One base station </li></ul><ul><li>The remote nodes can only send or receive a message from the base station </li></ul><ul><li>Advantages: simple, minimum power consumption </li></ul><ul><li>Disadvantages: the base station must be within radio transmission range of all individual nodes </li></ul>Nadège Barrage – ELEC6076 – Wireless Sensor Networks
  7. 7. <ul><li>Mesh Network: </li></ul><ul><li>Any node can transmit to any other node (if the node is within its radio transmission range): multihop communications </li></ul><ul><li>Advantages: redundancy, scalability </li></ul><ul><li>Disadvantages: power consumption higher for the nodes implementing the multihop communications (battery life limited) </li></ul>Nadège Barrage – ELEC6076 – Wireless Sensor Networks
  8. 8. <ul><li>Hybrid Star-Mesh Network: </li></ul><ul><li>The lowest power sensor nodes cannot forward messages </li></ul><ul><li>The other nodes are enabled with multihop capability so that the messages can be forwarded from the low power nodes to other nodes on the network </li></ul>Robust and versatile network, power consumption minimum. Nadège Barrage – ELEC6076 – Wireless Sensor Networks
  9. 9. <ul><li>Standards -> interoperability among multiple companies networks </li></ul><ul><li>Predominant standards for WSN communication: </li></ul><ul><li>Wi-Fi (IEEE802.11): for local area and high bandwidth data transfer between computers and other devices. </li></ul><ul><li>Data transfer rate ranges : 1 Mbps-50 Mbps </li></ul><ul><li>Typical transmission range: 300 feet </li></ul><ul><li>Disadvantages: power requirements quite high </li></ul><ul><li>Bluetooth (IEEE802.15.1 and .2): PAN lower power than Wi-Fi using a star network topology. </li></ul><ul><li>Disadvantages: can only support 7 nodes and relatively high power for a short transmission range </li></ul>Nadège Barrage – ELEC6076 – Wireless Sensor Networks
  10. 10. <ul><li>Zigbee (IEEE802.15.4): specifies the IEEE802.15.4 as the physical and MAC layer. It can support both star and hybrid star-mesh networks. IEEE802.15.4 is specifically designed for the requirement of wireless sensing applications. The hardware is designed to allow for the radio to be put to sleep. </li></ul><ul><li>Transmission frequencies: 868 MHz/902-928 MHz/2.48-2.5 GHz </li></ul><ul><li>Data rates: 20 Kbps, 50 Kbps and 250 Kbps </li></ul><ul><li>WirelessHART: used for industrial environments, it adopts the IEEE802.15.4 as the physical layer but defines its own time-synchronized MAC layer. It uses self-healing mesh network and meets the stringent requirements of industrial control. </li></ul>Nadège Barrage – ELEC6076 – Wireless Sensor Networks
  11. 11. <ul><li>Area monitoring: </li></ul><ul><li>Common application of WSNs </li></ul><ul><li>Nodes are deployed over a region where a phenomenon needs to be monitored </li></ul><ul><li>Event detected (pressure, vibration…) -> a base station receives the information and can take appropriate action </li></ul>Nadège Barrage – ELEC6076 – Wireless Sensor Networks <ul><li>Environmental monitoring: </li></ul><ul><li>Landslide detection: </li></ul><ul><li>WSNs used to detect the slight movements of soil </li></ul><ul><li>Data gathered by the base station -> the occurrence of landslides can be known long before it actually happens </li></ul>
  12. 12. <ul><li>Environmental monitoring: </li></ul><ul><li>Greenhouse monitoring: </li></ul><ul><li>WSNs used to control the temperature and humidity levels in greenhouses </li></ul><ul><li>Fall of temperature or humidity below a specific level -> information transmitted by the node to the base station which can send a notification to the greenhouse manager </li></ul><ul><li>WSNs easy to move -> ideal for this kind of application </li></ul><ul><li>Glacsweb: </li></ul><ul><li>Project at the University of Southampton using WSNs to monitor glacier behaviour. </li></ul><ul><li>Nodes are placed on and under glaciers in Norway. </li></ul>Nadège Barrage – ELEC6076 – Wireless Sensor Networks
  13. 13. <ul><li>Industrial monitoring: </li></ul><ul><li>Structural health monitoring: </li></ul><ul><li>Sensors embedded into machines, structures and previously inaccessible locations -> condition-based maintenance </li></ul><ul><li>Expensive method but can prevent the cost of catastrophic failure of one of the machine or structure. </li></ul><ul><li>WSNs can also be used for health monitoring of large civil structures, using strain gauges. </li></ul>Nadège Barrage – ELEC6076 – Wireless Sensor Networks
  14. 14. <ul><li>Industrial monitoring: </li></ul><ul><li>Industrial automation: </li></ul><ul><li>Use of wired sensors too cumbersome for a production line environment </li></ul><ul><li>Example of use: measurement of gaps where rubber seals are to be placed </li></ul>Nadège Barrage – ELEC6076 – Wireless Sensor Networks
  15. 15. <ul><li>Smart home: </li></ul><ul><li>A future application ! </li></ul><ul><li>It could control almost everything in a house! </li></ul>Nadège Barrage – ELEC6076 – Wireless Sensor Networks
  16. 16. Nadège Barrage – ELEC6076 – Wireless Sensor Networks <ul><li>Wireless sensing networks are very versatile. </li></ul><ul><li>Widespread development of WSNs in the future </li></ul><ul><li>Low power system absolutely necessary ; it is one of wireless sensor networks’ main challenges right now </li></ul>
  17. 17. <ul><li>Internet: </li></ul><ul><li>http://en.wikipedia.org/wiki/Wireless_sensor_network </li></ul><ul><li>http:// www.ece.ncsu.edu/wireless/wsn.html </li></ul><ul><li>http:// microstrain.com/white/Wilson-chapter-22.pdf </li></ul><ul><li>http://www.cs.utexas.edu/~ shan/paper/rtas08.pdf </li></ul><ul><li>http://envisense.org/glacsweb/index.html </li></ul><ul><li>Books: </li></ul><ul><li>Lewis, F.L., « Wireless Sensor Networks » , Smart Environ-ments: Technologies, Protocols, and Applications ed. D.J. Cook and S.K. Das, John Wiley, New York, 2004. </li></ul>Nadège Barrage – ELEC6076 – Wireless Sensor Networks

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