Wireless Sensor Networks Haywood Ho haywood.

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?

August 4, 2002 Wireless Sensor Networks

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

August 4, 2002 Wireless Sensor Networks

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

August 4, 2002 Wireless Sensor Networks

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

August 4, 2002 Wireless Sensor Networks

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