1. 15-446 Networked Systems Practicum Lecture 6 – RFID technology 1

2. Basic RFID NFC (RFID + Storage) Next Generation RFIDs (RFID + Computation + Storage) 2

3. RFID History First Bar code patents – 1930s First use of RFID device – 2nd world war – Brittan used RFID-like technology for Identify- Friend or Foe Harry Stockman October 1948 Paper – Communication by means of reflected power ( The proceedings of the Institute of Radio Engineers) First RFID Patent - 1973 Auto-ID center founded at MIT – 1999 Standardization effort taken over by EPC Global (Electronic Product Code) Current thrust primarily driven by Wal-Mart and DoD Automate Distribution: Reduce cost (man power, shipping mistakes) Increase sales (keep shelves full) DoD Total Asset Visibility Initiative

4. Basic Tag Operational Principles N S TAG Reader TAG Backscatter Near field (LF, HF): inductive coupling of tag to magnetic field circulating around antenna (like a transformer) Varying magnetic flux induces current in tag. Modulate tag load to communicate with reader field energy decreases proportionally to 1/R 3 (to first order) Far field (UHF, microwave): backscatter. Modulate back scatter by changing antenna impedance Field energy decreases proportionally to 1/R Boundry between near and far field: R = wavelength/2 pi so, once have reached far field, lower frequencies will have lost significantly more energy than high frequencies Absorption by non-conductive materials significant problem for microwave frequencies Inductive Coupling

5. Tag Details LFHFUHFMicrowave Freq. Range 125 - 134KHz13.56 MHz866 - 915MHz2.45 - 5.8 GHz Read Range 10 cm1M2-7 M1M Market share 74%17%6%3% Coupling Magnetic Electro magnetic Existing standards 11784/85, 1422318000-3.1, 15693,14443 A, B, and C EPC C0, C1, C1G2, 18000-6 18000-4 Application Smart Card, Ticketing, animal tagging, Access, Laundry Small item management, supply chain, Anti-theft, library, transportation Transportation vehicle ID, Access/Security, large item management, supply chain Transportation vehicle ID (road toll), Access/Security, large item management, supply chain

6. Types of Tags Passive Operational power scavenged from reader radiated power Semi-passive Operational power provided by battery Active Operational power provided by battery - transmitter built into tag

7. Real Tags

10. Electronic Product Code Header - Tag version number EPC Manager - Manufacturer ID Object class - Manufacturer ’ s product ID Serial Number - Unit ID With 96 bit code, 268 million companies can each categorize 16 million different products where each product category contains up to 687 billion individual units Note: 64 bit versions also defined, 256 bit version under definition

11. Class 1 Gen 2 tags 900 Mhz 10m range Downlink = information + energy 26.7 – 128kbps Uplink = energy sent down as continuous wave (CW) + modulate reflection coefficient of antenna 11

12. Multiple Tags? What happens when multiple tags are in range of the transceiver? All the tags will be excited at the same time. Makes it very difficult to distinguish between the tags.

13. Collision Avoidance Similar to network collision avoidance Probabilistic Tags return at random times Deterministic Reader searches for specific tags

14. CIG2 MAC 14

15. Traditional RFID Market Segments Auto Immobilizers Access Control Animal Tracking Automated Vehicle Id Isolated systemsIsolated systems Simple readsSimple reads Slow growthSlow growth

16. The New Mkt Segment Consumer Pkg Goods Supply Chain Wal-Mart June ’03 announcement Pallet/Case tagging  Top 100 suppliers Jan ’05  Other 30K by end of ’06 4 Billion tags/year 300k direct readers 18 Million indirect readers End to end systemsEnd to end systems Complex readsComplex reads Emerging marketEmerging market +

17. RFID in the Supply-Chain

18. Today: Outside the Supply Chain

19. Basic RFID NFC (RFID + Storage) Next Generation RFIDs (RFID + Computation + Storage) 19

20. NFC Phy 13.56MHz frequency, 14kHz band Range 4cm (max 20cm) Active (2 transmitters) and Passive (1 transmitter + load modulation) mode Data rate = 106, 212 or 424kbps 20

21. NFC Tag Types Type 1 and 2 96 or 48 bytes, 106kbps Read/write or read only Expansion to 2kbyte Type 3 2kbyte 212kbps Read-only Type 4 32kbyte 106-424 kbps Read-only 21

22. Basic RFID NFC (RFID + Storage) Next Generation RFIDs (RFID + Computation + Storage) 22

23. Collection of small, battery-powered sensing devices (motes) Peer-to-peer communication (multi-hop network) Range of monitoring applications: habitat monitoring, structural integrity of bridges volcanic activity, forest fires, etc. 23

24. UHF RFID EPC Class Gen 2 Powered reader infrastructure plus simple passive tags Direct reader to tag communication 4W EIRP from readers, tags “backscatter,” range of up to ~30ft Applications around inventory / supply chain management 24

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26. Combine the best of both: Small / inexpensive passive tags that sense/compute (WISPs) and communicate directly with apps in infrastructure (via readers) Key advantages: Ubiquitous, long-lived instrumentation, business simplicity, flexibility 26

27. Milk App Cold chain monitoring: Track many small items, e.g., bags of blood, items in fridge, with cheap and/or disposable tag Use proximity of readers to sense temperature and vital statistics when refrigerated most of the time Use stored energy (super-cap) to sense for brief periods when items are away from reader and exposed 27

28. Intermittent Power How do we run programs on WISPs with intermittent power? WISP power model: Gathers energy from readers, when in range (~15ft) at unpredictable times Has limited on board storage (capacitor << battery) Expends energy to sense/compute and communicate Slowly loses stored energy 28

29. WISP API to expose power state to application code “Enough power yet to complete this step?” Divide large computation into multiple small stages Store state in non-volatile memory or on readers Coordinate to match reader power to WISP needs Continue to provide for a sufficient interval Implications Lower reliability due to unpredictable contacts, power durations Variable frequency of operation due to “pre-charge” period 29