Wireless Sensor Networks

Haywood Hohttp://inst-eecs.berkeley.edu/

~haywood

August 4, 2002 Wireless Sensor Networks

Introduction

• What are wireless sensor networks?

• What’s the big deal?

August 4, 2002 Wireless Sensor Networks

‘Smart Dust’

• MICA• ATMEL

ATMEGA103 4MHz processor

• 512 KB flash memory, 4 KB RAM

• A/D converter• Network

reprogramming• Battery• Radio (916 MHz)

August 4, 2002 Wireless Sensor Networks

August 4, 2002 Wireless Sensor Networks

Operating System for ‘Smart Dust’

• Requirements– Consume little memory– Dynamic reprogramming– Robust and reliable performance

• Windows 98?

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TinyOS

• Tiny microthreaded Operating System

• Instead of in Windows XP, all based on threads, two levels of scheduling is used– Commands– Tasks

• Clock can wake mote, and then signal commands to be carried out

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Networking

• How do we network all the motes together?

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Network Discovery: Radio Cells

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Network Discovery

August 4, 2002 Wireless Sensor Networks

What’s the Big Deal?

• Tons of applications!– Prof Pister’s

predictions for 2010:• Augmented reality

displays• Color laser projection

systems• Virtual keyboards,

guitars• Smart homes and

offices

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What is the nearest available conference

room?

How many people are in the

gym? Is the treadmill free?

Motion Sensor:Room 3201 is

Empty

What is the average temperature on the

second floor?

Smart Office

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Applications

• Three applications currently under active research:– Defense-related sensor networks– Energy conservation– Real-time monitoring of structural

safety of buildings

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Defense-Related Sensor Networks

• 29 Palms Fixed/Mobile Experiment– Deploy a sensor network onto a road

from an unmanned aerial vehicle (UAV)– Establish communication among nodes – Detect and track vehicles passing

through– Transfer information from network to

UAV– Transfer information from UAV to

observer at base camp

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Flight Path

UAV

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Energy Conservation

• Replace faulty and obsolete sensors• Introducing light sensors would

allow lighting power consumption by 40%

• Cory Hall Demonstration (22 May 2001)

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Next Steps

• As a first step, instrument every room in a number of buildings on campus and collect data

• Later, real-time monitoring and control of power systems on campus

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Real-time Monitoring of Structural Safety of Buildings

• Difficult to discover hidden failures in structures

• Need to ensure safety may require lengthy inspection periods when buildings are closed

• Self-monitoring structures!

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• Motes clustered around critical points in structure

• Processing in mote network, allows transmission of only useful information

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• Wiring for traditional accelerometer sensors

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Instrumenting the Golden Gate Bridge!

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Conclusion

• Vast sensor networks would allow everyday objects to become “smart”

• Pervasive computing

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Mote management

• Long battery life required for practical implementations

• Control of power consumption crucial

• Power consumption:– 100 mW (on)– 30 µW (sleep)

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Defense-Related Sensor Networks

• Battlefield surveillance• Transportation monitoring• Scud hunting in Iraq