university college dublin adaptive radio modes in sensor networks: how deep to sleep? secon 2008 san...

UNIVERSITY COLLEGE DUBLIN

Adaptive Radio Modes in Sensor Networks: How Deep to Sleep?

SECON 2008

San Francisco, CA

June 17, 2008

Raja Jurdak

Antonio Ruzzelli

Gregory O’Hare University College Dublin, Ireland

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Outline Motivation

Protocols

Energy Model

Performance Evaluation

Conclusion

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Motivation

Need for energy-efficiency in WSNs Radio is a major energy sink Two major approaches for saving radio energy

Duty cycling Wake-up radio

Put radio into sleep mode (either periodically or on-demand)

Current IEEE 802.15.4 radios (e.g CC2420) provide multiple low power modes

Which radio mode is most energy-efficient?

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Radio Sleep Mode Tradeoffs

Deep sleep mode

Light sleep mode

Adapt radio sleep mode to current traffic conditions

µW

mW

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Outline Motivation

Protocols

Energy Model

Performance Evaluation

Conclusion

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Protocols 1/2 BMAC

IEEE 802.15.4

Periodically check for channel activity every T seconds

Sender uses preamble that has length P, with a duration of at least T seconds

Listener

SenderP

Idle Transmission

Data

T

Receiving

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Protocols 2/2RFIDImpulse Wake-up radio

based on RFID Attach tag to

external interrupt pin of MCU

Remotely trigger tag to wake up radio

Enables power down of MCU

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Outline Motivation

Protocols

Energy Model

Performance Evaluation

Conclusion

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Energy Model 1/3Listening Energy LPL

Listening Energy RFIDImpulse

Radio current consumption in sleep mode α

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Energy Model 2/3Switching Energy (for one state transition)

Cumulative Switching Energy (LPL)

Cumulative Switching Energy (RFIDImpulse)

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Energy Model 3/3Microcontroller Energy

Transmission Energy

Reception Energy

Sleeping Energy

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Outline Motivation

Protocols

Energy Model

Performance Evaluation

Conclusion

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Performance Evaluation

Apply energy model to following scenarios

Explore inter-dependencies among MAC protocols, node platforms, and traffic load in WSNs Energy tradeoffs Radio sleep mode optimization

Measured current values from node platforms 6-level binary tree static topology

BMAC 802.15.4 RFIDImpulse

MicaZ X X X

TelosB X X X

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Total Energy Low Traffic

MicaZ

TelosB

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Energy Tradeoffs Low Traffic

MicaZ

TelosB

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Total Energy High Traffic

MicaZ

TelosB

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Energy Tradeoffs High Traffic

MicaZ

TelosB

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Power Consumption versus Data Rate

MicaZ TelosB

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To Conclude

Contributions Proposed adaptive sleep modes according to current traffic

activity Presented comprehensive and generalizable energy model

for evaluating energy consumption Evaluated performance with 3 protocols and 2 node

platforms with measured current values Identified suitable radio sleep mode/protocol for given traffic

load on each node platform

Future workImplement mechanism to enable nodes to adapt their sleep

mode on the fly according to current traffic load

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Thanks for listening

Questions?

rjurdak@ieee.org