Management of Technology

Radio Frequency Identification

© 2006 Dr. R. Siriram

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RFID General Overview

Radio frequency identification

Is really not a specific technology, but an entire class of “Tagging” items by radio accomplished methods. This is done by a variety of means

RFID has been much hyped recently as a replacement for the barcode… and more..

Privacy concerns have cropped up

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RFID History

WWII roots as the British put IFF transponders in pallets (Identification: Freiend or Foe) to identify returning aircraft

In the 70’S, Los Alamos developed RFID tagging of nuclear equipment and personnel for safety

Amtech (Transcore) and Identronix spun off released research

Cattle stock monitoring, tracking (after trying and failing to use bar code technology) through railroads

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RFID History

Some obvious spin-offs:

Fleet vehicle identification (tractors/trailers/cargo)

Toll collection on highways

Fast lane (automated toll collection) uses an active transponder operating in the 900MHz band

Remote keyless entry

By 1984, several manufacturers, several flavors

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RFID Flavours

Operating Frequency

900/1800MHz, LF, MF, VHF, UHF, microwave

Programmability

WORM (Write once, read many times) usually at manufacture or installation

Direct contact or RF (reprogrammable 10,000-15,000 times)

Full read/write (Identronix had some 64KB proptotypes by 1984)

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RFID Flavours

Operating schemes

Transmitter- where batteries provide electrical power for tag (clearly has it’s disadvantages)

Transponder-where tag receives power and clocking from the reader…. This is what is of keen interest today.

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RFID Further Development

1985 AB RFID SYSTEM

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RFID Further Development

By the mid 1980’s, RFID development shifted to improve performance, cost, size rather than new applications

Many (BIG) companies were now getting involved: Motorola, TI, BTG, Microelectronic, Philips, Sokymat

A brief Foray into the technology

RFID (particularly the passive/transponder variety) by its very nature and design depend upon proximity

This relates to both how it works and how it is used.

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Sensetable

In Hiroshi’s group, Sensetable uses some varieties of RFID tagging

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Intel Research RFID Glove

• Glove-based reader and broadcast using Crossbow/UCB Mica2Dot Mote

• Some assembly parts are shown on the right

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Terminology

Passive tags

Power extracted from the RF field, no battery on board

Do not initiate communication, can only respond to reader

Semi-passive tags

They have a battery on board

Do not initiate communication, can only respond to reader

Active tags

They have a battery on board

They can initiate communication to reader

Possibly communicate peer-to-peer

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RFID Communication Model

Reader

Power from reader

Power commands

Tag responses

Reader antenna

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What does a reader do?

Remotely powers tags Establishes a bidirectional data link Inventories tags, filters tag reads Publishes reads to higher level data systems

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Case 1: One reader, one tag

Reader

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Case 2: One tag, many readers

Reader

Singulation

(Anti-collision)

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Case 3: Many readers, many tags

Reader

Reader

Channel

sharing

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RFID System engineering

Choice of operating frequency Regulatory limits Choice of communication protocols Tag IC, tag antenna design Reader, reader antenna design Proximate materials Sources of external interference

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RFID Operating Frequencies

US/Canada 125 KHZ 13.56 MHz 902-928 MHZ 2.4 GHz

EU 125 KHz 13.56 MHz 868-870 MHz 2.4 GHz

ASIA/Pacific 125 KHz 13.56 MHz 950-956 MHz 2.4 GHz

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RFID Operating Frequencies

Library book tracking

Pallet and container tracking

Building access control

Airline baggage tracking

Apparel item tracking

Does not work well near metal

Limited range, making it less useful for warehouse and many other supply chain related applications than UHF

Frequency accepted worldwide

Works well in most environments

In wide use today

High Frequency(HF)13.56 MHz

Animal ID

Beer tracking

Automobile ID and anti- theft systems

Limited read range, making it unsuitable for warehouse and many other supply chain related applications

Frequency accepted world wide

Works well near metal

In wide use today

Low Frequency (LF)125 KHz-134KHz

Common useLimitationsBenefitsRadio Frequency

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RFID Operating Frequencies

Access control for vehicles

Frequency not licensed worldwide

Complex systems development required

Not in wide use today

Read ranges longer than 6 feet

Microwave2.45GHz

Pallet and container tracking

Truck and trailer tracking (within shipping yards)

Tracking of individual items within pallets and containers

Frequency not licensed worldwide

Does not work well in moist environments

Read ranges longer than 6 feet

Rapidly growing commercial use (especially with supply chain applications)

Ultra High Frequency (UHF)868MHz-928MHz

Common useLimitationsBenefitsRadio Frequency

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Reader to tag power transfer

Reader

Reader Antenna

Separation distance d

• If a reader transmits Pr watts, how much power Pt does a tag receive at separation distance d?

• It depends

• At HF via inductive coupling : Pt ∞ 1/d3

• AT UHF via far field propagation: Pt ∞ 1/d2

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Limiting Factors for passive UHF RFID

• Reader transmitter power Pr (Gov. limited)

• Reader receiver sensitivity Sr

• Reader antenna gain Gr (Gov. limited)

• Tag antenna gain Gt (Size limited)

• Power required by tag Pt (Silicon processes limited)

• Tag modulator efficiency Et

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Typical UHF operating parameters

• Reader Transmit power Pr = 30dBm (1watt)

• Reader Receiver sensitivity Sr = -80Dbm(10-11 Watts)

• Reader Antenna Gain Gr = 6dBm

• Tag Power Requirement Pt = -10dBm (100 microwatts)

• Tag antenna gain Gt = 1dBi

• Tag Backscatter Efficiency Et = -20dB

• System operating wavelength = 33cm (915MHz)

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What is AIT?

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Automatic identification Technology Not just RFID

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Scenario

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Networked RFID Tags

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CMB Project

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Applications: Promotional Events

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Applications: Safe Return Home

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Applications: Road Information

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Convergence Trend

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Considerations

Usage parameters ( How far, how fast, how many, how much, applied to what, etc)

Tag and label issues Placement, orientation, design

Safety and regulation Frequency Security Privacy Backups Sensors/traducers

Interface Tag isolation

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Considerations

Data rates Protocol

Data fields Communication, who talks first

Power source Anti-collision

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Lesson’ learnt

Site survey is critical Determine frequency interferences in area Test plan is mandatory

Power is a major hurdle Computer connectivity is not always guaranteed Standards should be reviewed Interoperability, scalability, and modularity are critical to the

design requirements Reconfiguration of the facility could be a problem

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Controversy

The dark side of RFID tagging is that the technology could be used to invade privacy

Products could be tracked into a home, marketing could be targeted on products in the home, etc.

Purchases could be tied to people, etc.

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Conclusion

This is a very hot, hyped field right now, it remains to be seen how this technology is used.

Supply-chain people think it’s the best thing, ever, while privacy advocates think it’s the worst

There is plenty of info on RFID, Some reference sites are: