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Wireless Sensor Networks

Prithvi Security
Wireless Sensor Networks(WSNs) Specialists

Wireless Sensor Networks

  1. 1. Wireless Sensor Networks • A collection of sensing devices that can communicate wirelessly • Each device can sense, process, and talk to its peers • Typically, centralized collection point (sink or base station)
  2. 2. Sensor Node deployment and Communication Infrastructure Internet and Satellite Task Manager node Sink A B C D E Sensor Field Sensor Node User
  3. 3. Sensor Node A sensing node has 3 basic components: CPU  radio transceiver sensor array
  4. 4. Sensor Node Architecture
  5. 5. Sensors A sensor is a small hardware device which is capable of generating response to change in physical environment. Although sensors are of different type which are application specific but desired characteristics of a sensor node are small size and low power consumption
  6. 6. Energy conservation • Goal: unsupervised operation with no maintenance • Nodes need to conserve energy • Radio is power-hungry!
  7. 7. A WSN typically has little or no infrastructure. It consists of a number of sensor nodes (few tens to thousands) working together to monitor a region to obtain data about the environment.
  8. 8. Gateway Server Internet Communication’s barrier Sensor field Soil Moisture etc. Mote
  9. 9. Applications WSN applications can be classified into two categories: •Monitoring •Tracking
  10. 10. Monitoring applications •indoor/outdoor environmental monitoring viz., agriculture, air / water pollution •health and wellness monitoring, power monitoring, inventory •location monitoring, factory and process automation viz., pipeline •seismic and structural monitoring.
  11. 11. Tracking objects •animals •humans •vehicles.
  12. 12. Health Applications Sensor networks are also widely used in health care area. In some modern hospital sensor networks are constructed to monitor patient physiological data, to control the drug administration track and monitor patients and doctors and inside a hospital. They support fall detection, unconsciousness detection, vital sign monitoring and dietary/exercise monitoring.
  13. 13. WSNs are also used to form BAN(Body Area Network) which is placed close to body of patient and is used to monitor patient’s heart beat rate and breath rate and movements.
  14. 14. Military Applications Sensor networks can provide variety of services to military and air force like information collection, battlefield surveillance, intrusion detection and attack detection. In this field of application sensor networks have quite an advantage over other networks because enemy attacks can damage or destroy some of the nodes but nodes failure in WSN doesn’t affect the whole network.
  15. 15. Intrusion detection Sensor network can be used as a 2-phase in Intrusion Detection System. Instead of using mines intrusion can be detected by establishing sensor network in that area. Mines are dangerous to civilians so instead sensor nodes sense the detection and alarm the army. The response to prevent intrusion is now decided by the military.
  16. 16. Enemy Tracking and target classification Objects moving with significant metallic content can be detected using specially designed sensors. So enemies can be tracked and civilians are ignored. This system specially helps in detecting armed soldiers and vehicles.
  17. 17. Battlefield surveillance Critical areas and borders can be closely monitored using sensor networks to obtain information about any enemy activity in that area. This provides quick gathering of information provides time for quick response.
  18. 18. Battlefield damage assessment Sensor networks can be deployed after the battle or attacks to gather information of damage assessment.
  19. 19. Detection of NBC attacks Sensor networks can be used as Nuclear, Biological and Chemical warning system. If any nuclear biological or chemical agents can be detected by sensors and embedded alert system can now send a warning message. It provides the military critical response time to check the situation and prevent possible attacks which can save lives of many.
  20. 20. Targeting system Sensors can be embedded in weapons. Exact information about the target like distance, angle can be collected and sent to the shooter. So sensors can be collaborated with the weapons for better target assessment.
  21. 21. Agricultural Monitoring WSN in agriculture helps in distributed data collection, monitoring in harsh environments, precise irrigation and fertilizer supply to produce profuse crop production while diminishing cost and assisting farmers in real time data gathering.
  22. 22. The proposed agricultural environment monitoring server system collects environmental and soil information on the outdoors through WSN-based environmental and soil sensors.
  23. 23. Applications WSNs can be used for studying the local environment which is helpful in agriculture. Sensors are used to monitor the following conditions: Temperature Humidity Soil moisture Wind speed and direction Rainfall Sunshine Level of CO2
  24. 24. Precision Agriculture Precision agriculture is a method of farm management that enables farmers to produce more efficiently through a frugal use of resources. Motivation: •traditionally, a large farm is taken as homogeneous field in terms of resource distribution and its response to climate change, weeds, and pests •accordingly, farmers administer •fertilizers, pesticides, herbicides, and water resources •in reality, wide spatial diversity in soil types, nutrient content, and other important factors
  25. 25. Requirements of precision agriculture technologies •collect a large amount of data •over several days •monitoring the humidity and temperature conditions in the field •monitoring the wetness •determining the potential risk of the disease and the need for fungicides
  26. 26. Environmental Applications Another major area of application of WSN is environmental monitoring. WSNs are deployed for habitat monitoring, flood detections , forest fire detection etc.
  27. 27. Forest Fire detection Millions of sensor nodes can be deployed which use distributed sensing and collaborate with each other to provide information. So fire can be detected and exact location of fire origin can be provided before the fire is uncontrollable
  28. 28. Flood detection ALERT systems use sensors for rain, water level and weather. Information collected by these sensors can forecast the possible flood threats thus providing help for disaster management.
  29. 29. Pollution Monitoring WSNs can be deployed for monitoring the level of pollution and warning generation. Air Pollution Monitoring Systems are deployed in cities like London and Brisbane to monitor the level of pollutants. These sensor networks look for amount of poisonous gases and these statistics are studied to analyze if pollution has increased and take actions to check pollution
  30. 30. Disaster Management Applications WSNs can also be used for other disaster management like earthquake and landslide monitoring and disaster assessment.
  31. 31. Disaster monitoring Motivation •most of Earth’s changes of climate are hidden from view •at present, typical changes are monitored using expensive devices that are difficult to move
  32. 32. •the deployment and maintenance of these devices require expensive assistance •data storage must be retrieved on a periodic basis
  33. 33. WSNs can be very useful for weather / climate monitoring •a large number of small, cheap, and self-organizing nodes •can be deployed to cover a vast field
  34. 34. Advantage of WSNs in active disaster monitoring •fast and economical deployment •possible to achieve high spatial diversity •the networks can operate without requiring stringent maintenance routines
  35. 35. An important task in active disaster monitoring is to capture discrete events •eruptions, earthquakes, or tremor activities •these events are transient •occurring several times a day
  36. 36. Therefore, the researchers used the raw data to investigate volcanic activities the samples must be accurately time stamped to allow comparisons between correlated measurements
  37. 37. Conclusion •WSNs are suitable for capturing triggered events •WSNs are inadequate for capturing complete waveforms for a long period of time
  38. 38. Pipeline Monitoring Monitoring gas, water and oil pipelines Motivation: •management of pipelines presents a formidable challenge
  39. 39. •long length, high value, high risk •difficult access conditions •requires continuous and unobtrusive monitoring
  40. 40. Pipeline leakages can occur due to excessive deformations •Earthquakes •landslides or collisions with an external force
  41. 41. •corrosion, wear, material flaws •intentional damage to the structure
  42. 42. To detect leakages, it is vital to understand the characteristics of the substance the pipelines transport •fluid pipelines generate a hot-spot at the location of the leak •gas pipelines generate a cold-spot due to the gas pressure relaxation
  43. 43. •fluid travels at a higher propagation velocity in metal pipelines than in a Polyvinyl Chloride (PVC) •a large number of commercially available sensors to detect and localize thermal anomalies
  44. 44. •fiber optics sensors •temperature sensors •acoustic sensors
  45. 45. The PipeNet prototype The task is to monitor •hydraulic and water quality by measuring pressure and pH •the water level in combined sewer system •sewer collectors and combined sewer outflows
  46. 46. Industrial Sensing Managing inventory control Each item in a warehouse may have a sensor node attached to it. The end users can find out the exact location of the item with the help of sensor and tally the number of items in the same category stored in the database.
  47. 47. Structural Health Monitoring Motivation events: •on August 2, 2007, a highway bridge unexpectedly collapsed in Minnesota •nine people were killed in the event •potential causes: wear and tear, weather, and the weight of a nearby construction project •in fact, the BBC reported (August 14, 2007) that China had identified more than 6,000 bridges that were damaged or considered to be dangerous
  48. 48. these accidents motivate wireless sensor networks for monitoring bridges and similar structures
  49. 49. Motivation traditional inspections •visual inspection  everyday •labor-intensive, tedious, inconsistent, and subjective •basic inspections  at least once a year •detailed inspection  at least every five years on selected bridges •special inspections  according to technical needs •the rest require sophisticated tools  expensive, bulky, and power consuming
  50. 50. Underground Mining Motivation: one of the most dangerous work environments in the world incident of August 3, 2007 at the Crandall Canyon mine, Utah, USA
  51. 51. •six miners were trapped inside the coal mine •their precise location was not known
  52. 52. •the owners of the mine claimed a natural earthquake was the cause while scientists suspect the mine operations caused seismic spikes •a costly and irksome rescue attempt went underway
  53. 53. Advantages of WSNs over traditional methods Wide coverage Long monitoring periods No individual tracking Data available directly to researcher’s location Land and Aquatic Coverage Continuous monitoring
  54. 54. WSN Operating Systems •TinyOS •Contiki •MANTIS •Btnut •SOS •Nano-RK
  55. 55. TinyOS: •Event-driven programming model instead of multithreading •TinyOS and its programs written in nesC
  56. 56. TinyOS Charactersitics: •Small memory footprint non-preemptable FIFO task scheduling •Power Efficient Puts microcontroller to sleep Puts radio to sleep
  57. 57. •Concurrency-Intensive Operations Event-driven architecture Efficient Interrupts and event handling •No Real-time guarantees
  58. 58. WSN Simulators •NS-2 •GloMoSim •OPNET •SensorSim
  59. 59. •J-Sim •OMNeT++ •Sidh •SENS
  60. 60. WSN Emulators •TOSSIM •ATEMU •Avrora •EmStar

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