Outline What are wireless sensor networks? Dragon Star Lecture - - PDF document

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Dragon Star Lecture

Wireless Sensor Netw orks

Chenyang Lu

Department of Computer Science & Engineering Washington University in St. Louis May 2008

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Outline

• What are wireless sensor networks?
• Applications
• Course organization

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Smart Dust

• Processor + Sensors + Wireless Interface
• Miniature hardware manufactured economically in large numbers

Smart Dust (UCB)

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Mica2 Mote

128KB Instruction EEPROM 4KB Data EEPROM 512KB External Flash Memory (16 bytes x 32768 rows) Chipcon CC1000 radio, 38K or 19K baud, 315, 433, or 900MHz 51 pin I/O Connector SPI bus UART 2 2 AA ADC 0-7 UART 1 I2C Bus 3 LEDs Atmel ATmega128L μP 7.3827MHz To Sensors, JTAG, and/or Programming Board

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MTS420 Sensor Board

• GPS
• Accelerometer
• Light
• Temperature
• Humidity
• Barometric Pressure
• 2KB EEPROM Conf.

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Imote2

• Intel PXA271 Xscale

Processor

– 13-416MHz – 32MB FLASH/32MB SDRAM

• 802.15.4 Radio (2.4GHz)

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Applications

• Smart sensors

embedded in environments

• Wireless networking
• Fine-grained

monitoring & control

Structural Health Monitoring Inventory Management Fire Monitoring Habitat Monitoring

Modified from Deborah Estrin, SIGMETRICS keynote, http://lecs.cs.ucla.edu/~estrin/talks/Sigmetrics-June02.ppt

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Habitat Monitoring

Redw ood Trees

Source: David Culler’s MobiHoc’05 Keynote

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Habitat Monitoring

Great Duck Island

Source: IEEE Spectrum

Monitor

• usage patterns of burrows
• burrow and environmental changes
• differences between nesting areas and others

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Great Duck Island

Tiered Architecture

http://www.greatduckisland.net

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Great Duck Island

Requirements

• 9-month season low power low duty cycle
• Handle hash environment

– Verification network – Health monitoring

• Non-real-time, low data rate

– 5-10 min: entry/leave – 2-4 hr: environmental differential

• No in-network processing: data streaming

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Surveillance

Wireless Integrated Netw orked Sensors (WINS)

• Reliability

– Detection probability & false alarm rate

• Energy efficiency
• Real-time
• Low cost
• Solution: In-network processing in multi-tier network

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WINS

Tiered Architecture

• Tiers

– Low-power sensors provide continuous vigilance

• Seismic, infared, sound

– High-power sensors

• Cameras

– Human operators (most expensive!)

• Phased execution

– Low tier activate higher tier when necessary – Stop as soon as certainty threshold is reached

Power efficiency & reliability

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Medical Care

CodeBlue

Wireless pulse

• ximeter sensor

Wireless two-lead EKG Accelerometer, gyroscope, and electromyogram (EMG) sensor for stroke patient Monitoring

http://www.eecs.harvard.edu/~mdw/proj/codeblue/

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CodeBlue

Requirements

• Security & privacy
• Reliability
• Real-time

– Detect sudden change in patient conditions

• Mobility: Doctors, patients, equipments

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Structural Health Monitoring

Golden Gate Bridge

Source: David Culler’s MobiHoc’05 Keynote

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Structural Monitoring

• High sampling frequency

– A tri-axial accelerometer: 100 Hz sampling 4.8 Kbps

• Reliable data transfer
• Time synchronization
• Real-time: detect damage after earthquake

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Diverse Requirements

• Requirements are highly application-dependent
• Need to optimize design for specific applications

Real-time Security Reliability Energy GDI None None None Very Low WINS High High High Low CodeBlue High High High Medium GGB Medium None High Low

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Global Sensing

Beyond a Single Sensor Netw ork

Shipping Yard Ship Train Truck Customer, Shipper, DHS, CBP

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Summary: Applications

• Wireless sensor networks have been deployed

successfully in the real world.

• Tiered architecture is common

– Sensing, communication

• Diverse, application-specific challenges

– Energy, management, mobility, real-time, reliability, security, privacy……

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Topics

Date AM ( 10- 12) PM ( 1:30- 3:30) 5/ 26 Int roduct ion Operat ing Syst em 5/ 27 Programming Middleware 5/ 28 Media Access Cont rol MAC Layer Archit ect ure 5/ 29 Minimum Power Configurat ion Coverage & Connect ivit y 5/ 30 Query Scheduling Mobile Query

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Pointers

• http://www.cs.wustl.edu/~lu/ds08.html
• Feel free to ask questions and discuss!