Radio Frequency Identification (RFID) Technology

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Radio Frequency Identification (RFID) Technology

• Miodrag Bolic
• Associate Professor
• School of Information Technology and Engineering
• University of Ottawa
• mbolic_at_site.uottawa.ca

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Outline

• Introduction to RFID technology
• EPC Class 1 Generation 2

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RFID Sample Tags / Readers
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.
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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

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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)

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Tags

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

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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

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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

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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

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Protocols

• Tag singulation
• Tree based algorithms
• Aloha based algorithms

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Software and Integration
From http//www.infosys.com/rfid/Infosys_White_Pa
per_on_RFID_Architecture_Strategy.pdf
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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

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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

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EPC Classes
EPC Class I - V

• EPCglobal a joint subsidiary of the Uniform
  Code Council and EAN International

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EPC Standards Generation 2

• Specification recently approved by EPCglobal
• Designed to eventually replace Generation 1
  standards after a period of testing and transition

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UHF Class 1 Gen 2 Features
Requirement Gen2 Capability
Global Regulatory Compliance Europe, North America, Japan, etc.
Operation in Noisy Environments Multiple Sessions, Dense Reader Modes
Fast Operation gt 1600 tags/sec USA, 600 tags/sec Europe
Privacy Protection EPC code not broadcasted, 32-Bit Kill Password
Improved Accuracy Elimination of Ghost Reads, Adaptive Protocols
Memory Write Capability gt 7 tag/second write rate, Optional User Memory
Group Searches Filtering Flexible Select Command
Low Cost Multi-Vendor Availability
Flexibility Tolerates Identical EPC numbers Multiple EPCs
Certified products Currently Available
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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 (gt1,000 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.
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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

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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

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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/technicalArtic
les/Ecommerce/rfid/index.html
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Memory Organization
From EPCglobal. Class 1 Generation 2 UHF Air
Interface Protocol Standard Version 1.0.9, 2005.
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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

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Reader to tag data link
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OOK coding ASK
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Pulse interval encoding ASK
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Spectral mask
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Spectral mask for dense reader operation in
alternating 200kHz channals
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PSD for 40kHz data rate
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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)

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Tag to reader data link
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FM0
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Miller encoding
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Comparison of PSD of FM0 and Miller
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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

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Control frames
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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

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Class 1 Generation 2 Commands

• Select
• Inventory commands
• Query
• QueryAdjust
• QueryRep
• ACK
• NAK

• Access commands
• Req_RN
• Read
• Write
• Kill
• Lock
• Access
• BlockWrite
• BlockErase

From EPCglobal. Class 1 Generation 2 UHF Air
Interface Protocol Standard Version 1.0.9, 2005.
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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
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A?B Symmetry

• Gen2 doesnt 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
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3 Reader Interruptions

• Problem Handheld reader interrupts a dock-door
  reader
• Dont 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
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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

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

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Q algorithm