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Wireless Sensor Networks
A wireless sensor network consists of spatially distributed autonomous sensor nodes that monitor physical or environmental conditions. Sensor nodes gather data and relay it back to a main location. Wireless sensor networks enable monitoring of conditions such as temperature, sound, pollution levels, pressure, or motion over large areas. They have applications in industries such as agriculture, environmental protection, health care, home and building automation, and transportation.
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Wireless Sensor Networks
- 3. 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)
- 4. Sensor Node deploymentand Communication Infrastructure Internet and Satellite Task Manager node Sink A B C D E Sensor Field Sensor Node User
- 5. Sensor Node A sensingnode has 3 basic components: CPU radio transceiver sensor array
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- 7. Sensors A sensor isa 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
- 8. Energy conservation • Goal:unsupervised operation with no maintenance • Nodes need to conserve energy • Radio is power-hungry!
- 9. A WSN typicallyhas 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.
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- 11. Applications WSN applications canbe classified into two categories: •Monitoring •Tracking
- 12. Monitoring applications •indoor/outdoor environmentalmonitoring viz., agriculture, air / water pollution •health and wellness monitoring, power monitoring, inventory •location monitoring, factory and process automation viz., pipeline •seismic and structural monitoring.
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- 14. Health Applications Sensor networksare 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.
- 16. WSNs are alsoused 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.
- 18. Military Applications Sensor networkscan 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.
- 20. Intrusion detection Sensor networkcan 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.
- 21. Enemy Tracking andtarget 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.
- 22. Battlefield surveillance Critical areasand 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.
- 23. Battlefield damage assessment Sensornetworks can be deployed after the battle or attacks to gather information of damage assessment.
- 24. Detection of NBCattacks 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.
- 25. Targeting system Sensors canbe 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.
- 26. Agricultural Monitoring WSN inagriculture 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.
- 28. The proposed agriculturalenvironment monitoring server system collects environmental and soil information on the outdoors through WSN-based environmental and soil sensors.
- 29. Applications WSNs can beused 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
- 30. Precision Agriculture Precision agricultureis 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
- 31. Requirements of precisionagriculture 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
- 32. Environmental Applications Another major areaof application of WSN is environmental monitoring. WSNs are deployed for habitat monitoring, flood detections , forest fire detection etc.
- 34. Forest Fire detection Millionsof 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
- 35. Flood detection ALERT systemsuse sensors for rain, water level and weather. Information collected by these sensors can forecast the possible flood threats thus providing help for disaster management.
- 36. Pollution Monitoring WSNs canbe 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
- 38. Disaster Management Applications WSNs canalso be used for other disaster management like earthquake and landslide monitoring and disaster assessment.
- 40. Disaster monitoring Motivation •most ofEarth’s changes of climate are hidden from view •at present, typical changes are monitored using expensive devices that are difficult to move
- 41. •the deployment andmaintenance of these devices require expensive assistance •data storage must be retrieved on a periodic basis
- 42. WSNs can bevery useful for weather / climate monitoring •a large number of small, cheap, and self-organizing nodes •can be deployed to cover a vast field
- 43. Advantage of WSNsin active disaster monitoring •fast and economical deployment •possible to achieve high spatial diversity •the networks can operate without requiring stringent maintenance routines
- 44. An important taskin active disaster monitoring is to capture discrete events •eruptions, earthquakes, or tremor activities •these events are transient •occurring several times a day
- 45. Therefore, the researchersused the raw data to investigate volcanic activities the samples must be accurately time stamped to allow comparisons between correlated measurements
- 46. Conclusion •WSNs are suitablefor capturing triggered events •WSNs are inadequate for capturing complete waveforms for a long period of time
- 47. Pipeline Monitoring Monitoring gas,water and oil pipelines Motivation: •management of pipelines presents a formidable challenge
- 48. •long length, highvalue, high risk •difficult access conditions •requires continuous and unobtrusive monitoring
- 50. Pipeline leakages canoccur due to excessive deformations •Earthquakes •landslides or collisions with an external force
- 51. •corrosion, wear, materialflaws •intentional damage to the structure
- 52. 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
- 53. •fluid travels ata 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
- 54. •fiber optics sensors •temperaturesensors •acoustic sensors
- 55. The PipeNet prototype Thetask 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
- 56. Industrial Sensing Managing inventorycontrol 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.
- 57. Structural Health Monitoring Motivation events: •on August2, 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
- 58. these accidents motivatewireless sensor networks for monitoring bridges and similar structures
- 59. 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
- 60. Underground Mining Motivation: one ofthe most dangerous work environments in the world incident of August 3, 2007 at the Crandall Canyon mine, Utah, USA
- 61. •six miners weretrapped inside the coal mine •their precise location was not known
- 62. •the owners ofthe 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
- 63. Advantages of WSNsover traditional methods Wide coverage Long monitoring periods No individual tracking Data available directly to researcher’s location Land and Aquatic Coverage Continuous monitoring
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- 65. TinyOS: •Event-driven programming model insteadof multithreading •TinyOS and its programs written in nesC
- 66. TinyOS Charactersitics: •Small memoryfootprint non-preemptable FIFO task scheduling •Power Efficient Puts microcontroller to sleep Puts radio to sleep
- 67. •Concurrency-Intensive Operations Event-driven architecture EfficientInterrupts and event handling •No Real-time guarantees
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