Radio Frequency Identification

Prof. Hemang Kothari

What is RFID

• RFID is a technology, that incorporates electromagnetic coupling in the RF portion of the EM spectrum to uniquely identify an object, animal or person. It is also gaining increasing use in industry as an alternative to the bar code.

• Requires a transceiver, antenna, and transponder

• Can operate in Passive or Active Modes

What is RFID

• RF signals transmitted by the transceiver activates the transponder, which transmits data back to the transceiver.– Transponder is powered by EM waves emitted by

the transceiver• Various frequencies are used depending on

the application• Requires no line-of-sight (like bar-codes)

Application of RFID

• Supply chain automation• Asset tracking• Medical applications• People tracking• Manufacturing• Retail• Warehouses• Livestock• Timing

What Constitutes an RFID System?

• One or more RF tags• Two or more antennas• One or more host computers• Appropriate software

RFID API Software(Communicates with the RFID Reader)

Customer-SpecificApplication Software

Host ComputerHost Memory Space

Reader

Antenna

ApplicationProgramInterface

(API)

Components of an RFID System

TagInsert

Antenna Reader

Firmware

Customer’sMIS

Host

ApplicationSoftware API

TCP/IP

Power

~

Asset

Asset/Tag

RFID System Components(block diagram)

RESPONSES

COMMANDS

Tag Physical Memory

APPLICATIONRESPONSES

APPLICATION INTERROGATOR RF TAG

APPLICATIONCOMMANDS Command /

ResponseUnit

PHYSICALINTERROGATOR

DATA PROTOCOL PROCESSOR

ISO/IEC 15961 ISO/IEC 18000

Encoder

Logical Memory

AIR

INTERFACE

ISO/IEC 15962 ISO/IEC 15962 Annexes

Logical Memory

Map

Note: The Logical Memory Map in the Tag Physical Memory is given by the Tag architecture and the mapping rules in the Tag Driver. All the information in the Logical Memory is represented in

the Logical Memory Map

Decoder

Tag Driver

andMapping

Rules

Application Program

Interface

DEVICECOMMANDS

DEVICERESPONSES

RFID System Components(block diagram)

Sequence of Operation• Host Manages Reader(s) and Issues Commands• Reader and tag communicate via RF signal• Carrier signal generated by the reader (upon request from the

host application)• Carrier signal sent out through the antennas• Carrier signal hits tag(s)• Tag receives and modifies carrier signal• “sends back” modulated signal (Passive Backscatter - FCC and

ITU refer to as “field disturbance device”)• Antennas receive the modulated signal and send them to the

Reader

RFID Operation

The Tags

• An RFID tag is a device that can store and transmit data to a reader in a contact less manner using radio waves.

• Tags can be read-only or read-write• Tag memory can be factory or field programmed,

o able to partition, and optionally permanently locked

• Bytes left unlocked can be rewritten over more than100,000 times

Types of Tags

Active Tags• Has on-board power source

(for example, a battery; other sources of power, such as solar, are also possible)

• Own on-board power supply to transmit its data to a reader.

• No need for reader's emitted power for data transmission.

Passive Tags• No on-board power source

(for example, a battery)• Uses the power emitted from

the reader to energize itself and transmit its stored data to the reader

• Reader always communicates first, followed by the tag.

• Less costly compare to active tags

The Reader

• An RFID reader can read from and write data to compatible RFID tags.

• A reader thus doubles up as a writer. The act of writing the tag data by a reader is called creating a tag.

Component of Reader

• Transmitter• Receiver• Microprocessor• Memory• Controller (which may reside as an external

component)• Communication interface• Power

Reader and Tag Interaction

Inter digital transducer

TAG Internals

TAG & Reader Communication• A tag consist of a dipole antenna attached to an interdigital transducer

(IDT) placed on a piezoelectric substrate.• A series of well-placed individual electrodes acting as reflectors are

positioned on the substrate.• The antenna applies an electrical impulse to the IDT when it receives

the RF signal from a reader. • Some of these waves are reflected back to the IDT by the reflectors; the

rest are absorbed by the substrate. • The reflected waves form a unique pattern, determined by the reflector

positions, representing the tag data. • These waves are converted back to the RF signal in the IDT and

transmitted back to the RFID reader via the tag antenna. • The reader then decodes the received signal to extract the tag data.

Conclusion

• RFID, is an emerging technology which can be used for a variety of applications.

• Low cost but not lower than bar code.• Better way to do tracking• However, the potential for abuse of this

technology is vast and requires careful consideration to avoid.