Radio Frequency Identification (RFID) Technology

Miodrag BolicAssociate ProfessorSchool of Information Technology and EngineeringUniversity of Ottawambolic@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

Pallet tag, UHF (Matrics)

Cardboard-case tag, MW (Matrics)

Plastic crate tag, UHF (Rafsec)

Sample Tags Sample Readers

Stationary reader and antenna (Alien)

Signpost activator (Savi)

Stationary reader (Matrics)

Handheld reader (Checkpoint)

Doorway antenna (Checkpoint)

Stationary reader and antenna (SAMSys)

Stationary readers are typically deployed at warehouse portals or loading docks, on conveyor belts or forklift arms, on store shelves, check-out lanes, etc.

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

What is RFID? -- The What is RFID? -- The TagsTags

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)

Are All Tags The Same?Are All Tags The Same?

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_Paper_on_RFID_Architecture_Strategy.pdf

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

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 I - V

Class V tags Readers. Can power other Class I, II and III tags;

Communicate with Classes IV and V.

Class IV tags: Active tags with

broad-band peer-to-peer communication

Class III tags:semi-passive RFID tags

Class II tags: passive tags with additional

functionality

Class 0/Class I:read-only passive tags

EPC Classes EPCglobal – a joint subsidiary of the Uniform Code

Council and EAN International

UHF Class 1 Gen 2 FeaturesRequirement Gen2 Capability

Global Regulatory Compliance Europe, North America, Japan, etc.

Operation in Noisy Environments Multiple Sessions, Dense Reader Modes

Fast Operation > 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 > 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 (>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.

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/technicalArticles/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.

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.

#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?

Reset

• Late-arriving tags won’t hear the reset

• Multiple resets will interrupt a Query round

Source: Impinj

AB Symmetry Gen2 doesn’t put tags to sleep. It uses a “flag” instead

Flag can be set to “A” or “B”

Count tags from ABA 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

A

B

B

A

After ABA, all tags have been counted and are in A

Source: Impinj

A

B

B

AA

B

B

AA

B

B

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

A

B

B

A

Session 1Session 2

Session 3Session 4

Source: Impinj

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.

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

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