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Radio Frequency Identification (RFID) Technology

Radio Frequency Identification (RFID) Technology. Miodrag Bolic Associate Professor School of Information Technology and Engineering University of Ottawa mbolic@site.uottawa.ca. Outline. Introduction to RFID technology EPC Class 1 Generation 2. RFID – Sample Tags / Readers.

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Radio Frequency Identification (RFID) Technology

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  1. Radio Frequency Identification (RFID) Technology Miodrag Bolic Associate Professor School of Information Technology and Engineering University of Ottawa mbolic@site.uottawa.ca

  2. Outline • Introduction to RFID technology • EPC Class 1 Generation 2

  3. RFID – Sample Tags / Readers Signpost activator (Savi) Stationary reader and antenna (Alien) Handheld reader (Checkpoint) Plastic crate tag, UHF (Rafsec) Stationary reader (Matrics) Doorway antenna (Checkpoint) Stationary reader and antenna (SAMSys) Cardboard-case tag, MW (Matrics) Sample Tags Sample Readers Pallet tag, UHF (Matrics) Stationary readers are typically deployed at warehouse portals or loading docks, on conveyor belts or forklift arms, on store shelves, check-out lanes, etc.

  4. What is RFID? -- The Tags • Tags can be attached to almost anything: • pallets or cases of product • vehicles • company assets or personnel • items such as apparel, luggage, laundry • people, livestock, or pets • high value electronics such as computers, TVs, camcorders

  5. Are All Tags The Same? • Variations: • Memory • Size (16 bits - 512 kBytes +) • Read-Only, Read/Write or WORM • Type: EEProm, Antifuse • Arbitration (Anti-collision) • Ability to read/write one or many tags at a time • Frequency • 125KHz - 5.8 GHz • Physical Dimensions • Thumbnail to Brick sizes • Price ($0.50 to $250)

  6. Tags • Tag separation • Types of antennas • Dipole • Dual-dipole • ... • Material of the antennas: • copper, silver, film aluminium, ink

  7. Reader classification • Mobility • Fixed • Mobile • stand-alone or card interface • Intelligence • Intelligent – program and filter data • Nominal – read/write • Interface • Wired: TCT, RS232, USB • Wireless: WLAN

  8. Reader classification • Powering method • AC • Battery • DC from the forklift or a track • Reading mode • Autonomous • Interactive • Triggering device • Reducing interference • Connection with external devices • PDA, barcode readers, cameras

  9. Hand-held reader • Contain • UHF RFID reader • PDA computer that is embedded • WiFi, USB and RS232 connectivity, • external memory slot • bar code scanner • very often are sealed IP64 or IP65 • Options usually include: • GPS • Bluetooth • Camera module • Additional battery • 2D bar code scanner • Cradle • Other readers such as 13.56MHz readers • Printing labels

  10. Protocols • Tag singulation • Tree based algorithms • Aloha based algorithms

  11. Software and Integration From: http://www.infosys.com/rfid/Infosys_White_Paper_on_RFID_Architecture_Strategy.pdf

  12. RFID Architecture • Object Name Service (ONS) • Provides a global, distributed lookup service to translate an EPC into one URL where further information on the object (XML - metadata) may be found • Dynamic ONS services record a sequence of custodians as an object moves through a supply chain • Uses same technology of DNS • Integration and security are key • The Vertical-Based Extendable Mark-Up Language (XML) • XML vocabularies to represent and distribute information related to objects • Specific functionality data representation for specific industries

  13. EPC Class 1 Generation 2 UHF protocol • Intro and properties • Regulatory issues (pages 1-10 TI-RFID UHF Gen 2) • Tag memory organization • Reader and tags symbols and coding • Packet structure • Medium access control • States and commands • Link timing

  14. Class V tags Readers. Can power other Class I, II and III tags; Communicate with Classes IV and V. Class III tags:semi-passive RFID tags Class 0/Class I:read-only passive tags Class IV tags: Active tags withbroad-band peer-to-peer communication Class II tags: passive tags with additional functionality EPC Classes EPC Class I - V • EPCglobal – a joint subsidiary of the Uniform Code Council and EAN International

  15. UHF Class 1 Gen 2 Features

  16. Properties • Speed • 1500 tags/sec in North America • 600 tags/sec in Europe • 70ms to write 96-bit EPC • Reliability • Adapts to rapidly changing tag populations • Including large populations (>1,000 tags) • Can identify late-arriving tags immediately • Selection • Select command allows flexible tag pre-selection • Can select / mask specific tags for identification • Range • 8m read range • 6m write range From: EPCglobal. Class 1 Generation 2 UHF Air Interface Protocol Standard Version 1.0.9, 2005.

  17. EPC Class 1 Generation 2 UHF protocol • Intro and properties • Regulatory issues (pages 1-10 TI-RFID UHF Gen 2) • Tag memory organization • Reader and tags symbols and coding • Packet structure • Medium access control • States and commands • Link timing

  18. EPC Class 1 Generation 2 UHF protocol • Intro and properties • Regulatory issues (pages 1-10 TI-RFID UHF Gen 2) • Tag memory organization • Reader and tags symbols and coding • Packet structure • Medium access control • States and commands • Link timing

  19. EPC Data Standards • Electronic Product Code (EPC) • Uniquely identifies item in supply chain • 96 bit EPC • 268 million companies • Each with 16 million distinct object classes • Each class with 68 billion serial numbers From: http://java.sun.com/developer/technicalArticles/Ecommerce/rfid/index.html

  20. Memory Organization From: EPCglobal. Class 1 Generation 2 UHF Air Interface Protocol Standard Version 1.0.9, 2005.

  21. EPC Class 1 Generation 2 UHF protocol • Intro and properties • Regulatory issues (pages 1-10 TI-RFID UHF Gen 2) • Tag memory organization • Reader and tags symbols and coding • Packet structure • Medium access control • States and commands • Link timing

  22. Reader to tag data link

  23. OOK coding +ASK

  24. Pulse interval encoding +ASK

  25. Spectral mask

  26. Spectral mask for dense reader operation in alternating 200kHz channals

  27. PSD for 40kHz data rate

  28. Tag to Reader Modulation • The tag uses Backscatter modulation to respond to a reader. It does this by switching the reflection coefficient of its antenna (using a shunt circuit) from a matched load where the incident RF signal is absorbed, to a short at the antenna terminals where the maximum reflected RF signal is created. • The reader instructs the tag which method of data encoding to use when sending its data back: • Miller Subcarrier encoding • FM0 Baseband encoding The tag can use either/or two modulation formats - the tag manufacturer selects: • ASK (Amplitude Shift Keyed) • PSK (Phase Shift Keyed)

  29. Tag to reader data link

  30. FM0

  31. Miller encoding

  32. Comparison of PSD of FM0 and Miller

  33. EPC Class 1 Generation 2 UHF protocol • Intro and properties • Regulatory issues (pages 1-10 TI-RFID UHF Gen 2) • Tag memory organization • Reader and tags symbols and coding • Packet structure • Medium access control • States and commands • Link timing

  34. Control frames

  35. EPC Class 1 Generation 2 UHF protocol • Intro and properties • Regulatory issues (pages 1-10 TI-RFID UHF Gen 2) • Tag memory organization • Reader and tags symbols and coding • Packet structure • Medium access control • States and commands (pages 29-46 TI-RFID UHF Gen 2) • Link timing

  36. Select Inventory commands Query QueryAdjust QueryRep ACK NAK Access commands Req_RN Read Write Kill Lock Access BlockWrite BlockErase Class 1 Generation 2 Commands From: EPCglobal. Class 1 Generation 2 UHF Air Interface Protocol Standard Version 1.0.9, 2005.

  37. Reset • Late-arriving tags won’t hear the reset • Multiple resets will interrupt a Query round #2: Tags That Oversleep • Fact: Some tags are heavy sleepers • Problem: A tag may still be asleep, from being counted by a prior reader, when it reaches me • How do I count it? Source: Impinj

  38. AB Symmetry • Gen2 doesn’t put tags to sleep. It uses a “flag” instead • Flag can be set to “A” or “B” • Count tags from ABA • Step 1: Query(A) • Only “A” tags respond • “A” tags set their flag to “B” when they are counted • Step 2: Query(B) • Only “B” tags respond • “B” tags set their flag to “A” when they are counted • Go to step 1 After ABA, all tags have been counted and are in A A B B A Source: Impinj

  39. A A A A B B B B B B B B A A A A #3: Reader Interruptions • Problem: Handheld reader interrupts a dock-door reader • Don’t want the dock-door reader to lose its ongoing inventory • Solution: Tags have 4 flags rather than just 1 • One for each of 4 sessions • A reader Queries tags in a single session • Different readers can use different sessions • Example • Shelf reader uses session #1; handheld reader uses session #2 Session 4 Session 3 Session 2 Session 1 Source: Impinj

  40. EPC Class 1 Generation 2 UHF protocol • Intro and properties • Regulatory issues (pages 1-10 TI-RFID UHF Gen 2) • Tag memory organization • Reader and tags symbols and coding • Packet structure • States and commands • Link timing • Medium access control

  41. Link timing From: EPCglobal. Class 1 Generation 2 UHF Air Interface Protocol Standard Version 1.0.9, 2005.

  42. EPC Class 1 Generation 2 UHF protocol • Intro and properties • Regulatory issues (pages 1-10 TI-RFID UHF Gen 2) • Tag memory organization • Reader and tags symbols and coding • Packet structure • Medium access control • States and commands • Link timing

  43. Q algorithm

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