Wireless Sensor Networks -...
Transcript of Wireless Sensor Networks -...
Wireless Sensor Networks
Atiq Ahmed
Outline
• Motes & Wireless Sensor Networks
• WSN Applications
9/8/2016 Introduction to WSN 2
Mote
Dig
ita
l I/O
po
rts
Radio Transceiver
An
alo
g I
/O P
ort
s
Microcontroller
A/D
D/A
Sensor
Sensor
• A very low cost low power computer
• Monitors one or more sensors
• A Radio Link to the outside world
• Are the building blocks of Wireless Sensor Networks (WSN)
External Memory
Dig
ita
l I/O
po
rts
9/8/2016 Introduction to WSN 3
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 environmental conditions, such as
temperature, sound, vibration, pressure, motion or pollutants, at different locations.”
- Wikipedia
9/8/2016 Introduction to WSN 4
Wireless Sensor Network
• WSNs are networks that consists of sensors which
are distributed in an ad hoc manner
• These sensors work with each other to sense some
physical phenomenon and then the information physical phenomenon and then the information
gathered is processed to get relevant results
• WSNs consists of protocols and algorithms with self-
organizing capabilities
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Wireless Sensor Networks
• Formed by hundreds or thousands of motes that communicate with each other and pass data along from one to data along from one to another
• Research focuses mostly on energy aware computing and distributed computing
9/8/2016 Introduction to WSN 6
WSN node components
• Low-power processor.– Limited processing.
• Memory.– Limited storage.
• Radio.– Low-power.
Sensors
P
O
W– Low-power.
– Low data rate.
– Limited range.
• Sensors.– Scalar sensors: temperature,
light, etc.
– Cameras, microphones.
• Power.
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Processor
Radio
StorageW
E
R
WSN device schematics
Introduction to WSN
Why Now?
• Use of networked sensors dates back to the
1970s
– Primarily wired and
– “Centralized”– “Centralized”
• Today, enabling technological advances in
VLSI, MEMS1, and wireless communications
– Ubiquitous computing and
– Ubiquitous communications
9/8/2016 Introduction to WSN 8
1Microelectromechanical systems
Vision: Embed the World
•Embed numerous sensing nodes
to monitor and interact with
physical world
•Network these devices so that
they can execute more complex
task
9/8/2016 Introduction to WSN 9
Examples of WSN Platforms
PC-104+
(off-the-shelf)
UCLA TAG
(Girod)UCB Mote
(Pister/Culler)
9/8/2016 Introduction to WSN 10
Example of WSNSource: http://esd.sci.univr.it
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Comparison with ad hoc networks
– WSNs mainly use broadcast communication while ad hoc networks use point-to-point communication
– Unlike ad hoc networks, WSNs are limited by sensorslimited power, energy and computational capabilitylimited power, energy and computational capability
– Sensor nodes may not have global ID because of the large amount of overhead and large number of sensors
– The number of nodes is very large
– Being more prone to failure, energy drain
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Characteristics of Wireless Sensor
Networks• WSNs mainly consists of sensors which are -
– low power
– limited memory
– energy constrained due to their small size
• Wireless networks can also be deployed in extreme • Wireless networks can also be deployed in extreme environmental conditions and may be prone to enemy attacks
• Although deployed in an ad hoc manner they need to be self organized and self healing and can face constant reconfiguration
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Design Challenges
• Heterogeneity
– The devices deployed maybe of various types and need to collaborate with each other
• Distributed Processing• Distributed Processing
– The algorithms need to be centralized as the processing is carried out on different nodes
• Low Bandwidth Communication
– The data should be transferred efficiently between sensors
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Continued..
• Large Scale Coordination
– Sensors need to coordinate with each other to produce required results
• Utilization of Sensors• Utilization of Sensors
– Sensors should be utilized in a ways that produce the maximum performance and use less energy
• Real Time Computation
– Computation should be done quickly as new data is always being generated
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Operational Challenges of Wireless Sensor
Networks
• Energy Efficiency
• Limited storage and computation
• Low bandwidth and high error rates
• Errors are common• Errors are common
– Wireless communication
– Noisy measurements
– Node failure are expected
• Scalability to a large number of sensor nodes
• Survivability in harsh environments
• Experiments are time- and space-intensive
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Enabling Technologies
EmbeddedNetworked
Control system w/
Small form factor Exploit
Embed numerous distributed
devices to monitor and interact
with physical world
Network devices to coordinate and
perform higher-level tasks
Sensing
Small form factor
Untethered nodes
Exploit
collaborative
Sensing, action
Tightly coupled to physical world
Exploit spatially and temporally dense, in situ, sensing and actuation
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Applications of Wireless Sensor networks
Applications can be divided in three categories
I. Monitoring of objectsI. Monitoring of objects
II. Monitoring of an area
III. Monitoring of both area and objects
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WSN Applications
• Environmental/Habitat monitoring
• Acoustic detection
• Seismic Detection
• Military surveillance • Military surveillance
• Inventory tracking
• Medical monitoring
• Smart spaces
• Process Monitoring
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Biomedical / Medical
• Health Monitors
– Glucose
– Heart rate
– Cancer detection
• Chronic Diseases
– Artificial retina
– Cochlear implants
• Hospital Sensors
– Monitor vital signs
– Record anomalies
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Military
Remote deployment of sensors for tactical monitoring of enemy
troop movements
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Industrial & Commercial
• Numerous industrial and commercial
applications:
– Agricultural Crop Conditions
– Inventory Tracking– Inventory Tracking
– In-Process Parts Tracking
– Automated Problem Reporting
– RFID – Theft Deterrent and Customer Tracing
– Plant Equipment Maintenance Monitoring
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Habitat Monitoring on Great Duck IslandSource: http://www.greatduckisland.net/
• Intel Research Laboratory at Berkeley initiated a collaboration with the College of the Atlantic in Bar Harbor and the University of California at Berkeley to deploy wireless sensor networks on Great Duck Island, Maine (in 2002)
• Monitor the microclimates in and around nesting burrows used by the Leach's Storm PetrelPetrel
• Goal : habitat monitoring kit for researchers worldwide
9/8/2016 Introduction to WSN 23
FireBug by UCBSource: D. M. Doolin and N. Sitar. Wireless sensors for wild fire monitoring, Proceedings of SPIE / NDE 2005.
• Wildfire Instrumentation System Using Networked Sensors
• Allows predictive analysis of evolving fire behavior
• Firebugs: GPS-enabled, wireless thermal sensor motes based on TinyOS that self-organize into networks for collecting real time data in wild fire environments
• Software architecture: Several interacting layers (Sensors, Processing of sensor data, Command center)
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Example: Precision Agriculture
• Precision agriculture aims at
making cultural operations
more efficient, while reducing
environmental impact
• Collected information is used
to evaluate optimum sowing
density, estimate fertilizers
and other inputs needs, and
to more accurately predict
crop yields
Introduction to WSN9/8/2016
Source: Aslan, et el. "A framework for use of
wireless sensor networks in forest fire
detection and monitoring." Computers,
Environment and Urban Systems 36.6 (2012):
614-625. 25
Preventive Maintenance on an Oil
• Collaboration of Intel & British Petroleum
• Use of sensor networks to support preventive maintenance on board an oil tanker in the North Sea
• A sensor network deployment onboard • A sensor network deployment onboard the ship
• System gathered data reliably and recovered from errors when they occurred
• The project was recognized by InfoWorld as one of the top 100 IT projects in 2004
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• Basically a location-aware mote
• Includes an Ultrasound transmitter and receiver
• Uses the combination of RF and Ultrasound technologies to establish differential time of arrival and hence linear range
estimates
“Cricket” Mote
estimates
• Based on Cricket Indoor Location System developed by MIT
9/8/2016 Introduction to WSN 27
• Organizes the sensor
nodes into clusters
• Each cluster is governed
by a cluster-head
Clustered Architecture
by a cluster-head
• Only heads send
messages to a BS
• Suitable for data fusion
• Self-organizing
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Low-Energy Adaptive Clustering Hierarchy
(LEACH)
• Self-organizing and adaptive clustering protocol
• Evenly distributes the energy expenditure among the
sensors
• Performs data aggregation where cluster heads act • Performs data aggregation where cluster heads act
as aggregation points
• Two main phases:
– Setup phase: organizing the clusters
– Steady-state phase: deals with the actual data transfers to
the BS
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TinyOS• What is TinyOS?
– open-source operating system
– wireless embedded sensor networks
– component-based architecture
• Developed at UCB in collaboration with Intel Research
• Current Stable Version is 1.1.15• Current Stable Version is 1.1.15
• TinyOS 2.0 (T2) released on 6/11
• Main Ideas –– Low complexity
– Conserve power – sleep as frequently as possible
• Written in nesC – next generation C compiler
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Different Targets
mica mica2 mica2dot micaz
telos telosb rene2 pc
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Mica2
• Extremely popular mote
• 8-bit AVR Controller
• FSK radio
• Data-logger flash• Data-logger flash
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Telosb Motes
• Have USB programming capability
• An IEEE 802.15.4 compliant, high data rate radio with integrated antenna, a low-power MCU with integrated antenna, a low-power MCU
• Also equipped with extended memory and an optional sensor suite
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Future of WSNSmart Home / Smart Office
• Sensors controlling
appliances and electrical
devices in the house
• Better lighting and • Better lighting and
heating in office
buildings
• The Pentagon building
has used sensors
extensively
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References1. Akyildiz, Ian F., and Mehmet Can Vuran. Wireless sensor networks. Vol. 4. John
Wiley & Sons, 2010.
2. Stankovic, John A. "Wireless Sensor Networks." IEEE Computer 41.10 (2008): 92-95.
3. Yang, Kun. "Wireless sensor networks." Principles, Design and Applications(2014).
4. Ye, Wei, et al. "An energy-efficient MAC protocol for wireless sensor networks." INFOCOM 2002. IEEE. Vol. 3. IEEE, 2002.
5. Patwari, Neal, et al. "Locating the nodes: cooperative localization in wireless sensor networks." IEEE Signal processing magazine 22.4 (2005): 54-69.sensor networks." IEEE Signal processing magazine 22.4 (2005): 54-69.
6. Al-Karaki, et al. "Routing techniques in wireless sensor networks: a survey." IEEE wireless communications 11.6 (2004): 6-28.
7. Pal, Amitangshu. "Localization algorithms in wireless sensor networks: Current approaches and future challenges." Network protocols and algorithms 2.1 (2010): 45-73.
8. Ozturk, Yusuf, et al. "An intelligent home energy management system to improve demand response." IEEE Transactions on Smart Grid 4.2 (2013): 694-701.
9. Dong, Wei, et al. "DPLC: Dynamic packet length control in wireless sensor networks." INFOCOM, 2010 Proceedings IEEE. IEEE, 2010.
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