RFID Sensor NetworksJoshua R. SmithAssociate ProfessorComputer Science & Engineering andElectrical EngineeringUniversity of Washington

FISC 2030

March 22, 2012

RFID Sensor NetworksJoshua R. SmithAssociate ProfessorComputer Science & Engineering andElectrical EngineeringUniversity of Washington

FISC 2030

March 22, 2012

WISP 3 axis x 10 bit accelerometer

First UHF RFID w/ accelerometer

RFID Sensor Networks with the Intel WISP Winner Best Demo, Sensys 08M. Buettner, B. Greenstein, R. Prasad, A. Sample, J.R. Smith, D. Yeager, D. Wetherall.

WISP: A Passively Powered UHF RFID Tag with Sensing and Computation, D.J. Yeager, A.P. Sample, J.R. Smith, in S.A. Ahson, M. Ilyas Eds. RFID Handbook: Applications, Technology, Security, and Privacy, CRC Press.

WISP: Wireless Identification and Sensing Platform

WISP & UHF RFIDUHF RFID: Much longer range than earlier generations of RFID (up to 30 feet)Uplink communication by “backscatter” (reflection)…very low powerBackscatter energy efficiency improves with Moore’s law, unlike conventional radio!!WISP has no battery…powered by “reader” deviceWISP: Programmable, software defined, sensor-extensible RFID tag

RFID readerant

Tag

TagPower & data (“downlink”)

Data (“uplink”)

WARP – Ambient RF HarvestingWARP: Wireless Ambient Radio Power

1 MW TV transmitter – 4.2 km distance

Harvests from environmental RF sources Television band GSM band

Onboard sensing and computation

Low-power radio uplink

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“Wireless Ambient Radio Power,” A.P. Sample, A.N. Parks, S. Southwood, J.R. Smith inWirelessly Powered Sensor Networks and Computational RFID, Springer, 2012

WARP – Ambient RF Harvesting Battery-free environmental sensing

Weather statistics Toxic gas monitoring (e.g., CO)

Next Steps Extended range radio Optimized harvesting and storage GSM Harvesting

“Printed Low Power Amperometric Gas Sensors Employing RF Energy Harvesting”M. Carter, J. Stetter, J. Smith, A. Parks, Y. Zhao, M. Findlay, V. Patel, Proceedings221st ElectroChemical Society Meeting, May 2012

Key enabling trend

Range scaling of far field WPT

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Friis(Moore(t)) wireless power range scales exponentially (!) … …but with exponent that is ½ of EPI (IPuJ) scaling

Inst/Jdoubling time2 years

Rangedoubling time4 years

0.232 td

While Inst/J is continuing to scale, voltage scaling is ending. Thus techniques to efficiently harvest at low voltage are desirable.

Possible outcome if voltage scaling limits cannot be compensatedfor

from Mapping the space of wirelessly powered systemsin Wirelessly Powered Sensor Networks and Computational RFIDJoshua R. Smith Ed., Springer 2012

What does this scaling trend mean?

Capabilities that barely work today will become robust in the future

“Low end” devices like RFID tags will get increasing compute functionality, e.g. full-programmability

It will become possible to RF-power devices that seem too power-hungry today, e.g.

• microphones

• cameras

Research effort is needed to overcome the voltage scaling challenge

Bad news: the further away we are, the lower the voltage

Good news: voltage is not a conserved quantity…can be boosted!

8

Hybrid analog / digital backscatter sensing

The original Great Seal bug aka “The Thing”

Our idea:

WISPA digitally addressable passive backscatter micthat will be read by a SW Defined RFID reader

Combine benefits of analog (low power sensing)with digital (addressability, channel sharing, error correction, …)

Amazing that RFID reader can collect sound from a totally passive microphone! Theremin has come full circle.

Analog backscatter using SW Defined RFID Readers | Talla, Buettner, Wetherall, SmithIEEE RFID 2012

Digital / analog backscatter traces

4/11/201210

Default mode: Digital modeEPC Gen2 inventory followed by analog backscatter mode (1 second long)After 1 second in analog mode, switch to digital mode

Message exchanges between Reader and WISP

1 foot

5 feet

WREL Wireless power

“Analysis, Experimental Results, and Range Adaptation of Magnetically Coupled Resonators for Wireless Power Transfer,” A.P. Sample, D.T. Meyer, J.R. Smith, IEEE Transactions on Industrial Electronics, Feb. 2011, vol.58, no.2, pp.544-554

Powering a Ventricular Assist Device (VAD) with the Free-Range Resonant Electrical Energy Delivery (FREE-D) System, Benjamin H. Waters, Alanson P. Sample, PramodBonde, Joshua R. Smith, Proceedings of the IEEE , vol.100, no.1, pp.138-49, January 2012.

Future work:Extreme wirelessly powered sensor systems

Fully implantable, fully wireless, perpetual

• Heart pumps

• Neural implants

• Wirelessly powered telephones / listening devices

• RF-powered & read camera

• SMS-powered SMS messaging

Intel Science & Technology Center for Pervasive Computing5 year center funded by Intel

Acknowledgement

http://istc-pc.washington.edu

ECCS-0824265, "Realizing the internet of things with RFID sensor networks"

NSF EEC 1028725 “NSF Engineering Research Center for Sensorimotor Neural Engineering”

Faculty Research Award