1. 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

2. UNIVERSITY COLLEGE DUBLIN Outline  Motivation  Protocols  Energy Model  Performance Evaluation  Conclusion

3. UNIVERSITY COLLEGE DUBLIN 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?

4. UNIVERSITY COLLEGE DUBLIN Radio Sleep Mode Tradeoffs Deep sleep mode Light sleep mode  Adapt radio sleep mode to current traffic conditions µW mW

5. UNIVERSITY COLLEGE DUBLIN Outline  Motivation  Protocols  Energy Model  Performance Evaluation  Conclusion

6. UNIVERSITY COLLEGE DUBLIN 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 Sender P IdleTransmission Data T Receiving

7. UNIVERSITY COLLEGE DUBLIN Protocols 2/2 RFIDImpulse  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

8. UNIVERSITY COLLEGE DUBLIN Outline  Motivation  Protocols  Energy Model  Performance Evaluation  Conclusion

9. UNIVERSITY COLLEGE DUBLIN Energy Model 1/3 Listening Energy LPL Listening Energy RFIDImpulse Radio current consumption in sleep mode α

10. UNIVERSITY COLLEGE DUBLIN Energy Model 2/3 Switching Energy (for one state transition) Cumulative Switching Energy (LPL) Cumulative Switching Energy (RFIDImpulse)

11. UNIVERSITY COLLEGE DUBLIN Energy Model 3/3 Microcontroller Energy Transmission Energy Reception Energy Sleeping Energy

12. UNIVERSITY COLLEGE DUBLIN Outline  Motivation  Protocols  Energy Model  Performance Evaluation  Conclusion

13. UNIVERSITY COLLEGE DUBLIN 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 BMAC802.15.4RFIDImpulse MicaZXXX TelosBXXX

14. UNIVERSITY COLLEGE DUBLIN Total Energy Low Traffic MicaZ TelosB

15. UNIVERSITY COLLEGE DUBLIN Energy Tradeoffs Low Traffic MicaZ TelosB

16. UNIVERSITY COLLEGE DUBLIN Total Energy High Traffic MicaZ TelosB

17. UNIVERSITY COLLEGE DUBLIN Energy Tradeoffs High Traffic MicaZ TelosB

18. UNIVERSITY COLLEGE DUBLIN Power Consumption versus Data Rate MicaZTelosB

19. UNIVERSITY COLLEGE DUBLIN 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 work Implement mechanism to enable nodes to adapt their sleep mode on the fly according to current traffic load

20. UNIVERSITY COLLEGE DUBLIN Thanks for listening Questions? rjurdak@ieee.org