CHAPTER 1 - INTRODUCTION 1.1 RADIO FREQUENCY IDENTIFICATION-AN OVERVIEW RFID is only one of numerous technologies grouped under the term Automatic Identification (Auto ID), such as bar code, magnetic inks, optical character recognition, voice recognition, touch memory, smart cards, biometrics etc. Auto ID technologies are a new way of controlling information and material flow, especially suitable for large production networks. In RFID systems, an item is tagged with a tiny silicon chip and an antenna; the chip plus antenna together called a “tag” can then be scanned by mobile or stationary readers, using radio waves (the “RF”). The chip can be encoded with a unique identifier, allowing tagged items to be individually identified by a reader (the “ID”). Thus, for example, in a clothing store, each particular suit jacket, including its style, colour, and size, can be identified electronically. In a pharmacy, a druggist can fill a prescription from a bottle bearing an RFID-chipped label confirming the authenticity of its contents. On the highway, cars with RFID tags on their windshields can move swiftly through highway tollbooths, saving time and reducing traffic congestion. At home, pets can be implanted with chips so that lost animals can be identified and returned to their owners more readily. In each case, a reader must scan the tag for the data it contains and 1
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CHAPTER 1 - INTRODUCTION
1.1 RADIO FREQUENCY IDENTIFICATION-AN OVERVIEW
RFID is only one of numerous technologies grouped under the term Automatic
Identification (Auto ID), such as bar code, magnetic inks, optical character recognition,
voice recognition, touch memory, smart cards, biometrics etc. Auto ID technologies are a
new way of controlling information and material flow, especially suitable for large
production networks.
In RFID systems, an item is tagged with a tiny silicon chip and an antenna; the chip
plus antenna together called a “tag” can then be scanned by mobile or stationary readers,
using radio waves (the “RF”). The chip can be encoded with a unique identifier, allowing
tagged items to be individually identified by a reader (the “ID”). Thus, for example, in a
clothing store, each particular suit jacket, including its style, colour, and size, can be
identified electronically. In a pharmacy, a druggist can fill a prescription from a bottle
bearing an RFID-chipped label confirming the authenticity of its contents. On the highway,
cars with RFID tags on their windshields can move swiftly through highway tollbooths,
saving time and reducing traffic congestion. At home, pets can be implanted with chips so
that lost animals can be identified and returned to their owners more readily. In each case, a
reader must scan the tag for the data it contains and then send that information to a database,
which interprets the data stored on the tag. The tag, reader, and database are the key
components of an RFID system.
Radio-frequency identification (RFID) is the use of a wireless non-contact radio
system to transfer data from a tag attached to an object, for the purposes of automatic
identification and tracking. Some tags require no battery and are powered by the radio
waves used to read them. Others use a local power source. The tag contains electronically
stored information which can be read from up to several metres (yards) away. Unlike a bar
code, the tag does not need to be within line of sight of the reader and may be embedded in
the tracked object.
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1.2 PRIMARY COMPONENTS OF RFID DEVICES
RFID devices have three primary elements: a chip, an antenna, and a reader. A
fourth important part of any RFID system is the database where information about tagged
objects is stored.
1.2.1 THE CHIP, usually made of silicon, contains information about the item to which it
is attached. Chips used by retailers and manufacturers to identify consumer goods may
contain an Electronic Product Code (“EPC”). The EPC is the RFID equivalent of the
familiar Universal Product Code (“UPC”), or bar code, currently imprinted on many
products. Bar codes must be optically scanned, and contain only generic product
information. By contrast, EPC chips are encrypted with a unique product code that
identifies the individual product to which it is attached, and can be read using radio
frequency. These codes contain the type of data that product manufacturers and retailers
will use to track the authenticity and location of goods throughout the supply chain.
An RFID chip may also contain information other than an EPC, such as biometric
data (a digitized image of a fingerprint or photograph, for example). In addition, some chips
may not be loaded with information uniquely identifying the tagged object at all; so-called
“electronic article surveillance systems” (“EAS”) may utilize 3 radio frequency
communication to combat shoplifting, but not to uniquely identify individual items.
Fig 1.1 – key ring tag
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1.2.2 THE ANTENNA attached to the chip is responsible for transmitting information from
the chip to the reader, using radio waves. Generally, the bigger the antenna, the longer the
read range. The chip and antenna combination is referred to as a transponder or, more
commonly, as a tag. Antennas are available in a variety of shapes and sizes; they can be
built into a door frame to receive tag data from persons or things passing through the door,
or mounted on an interstate tollbooth to monitor traffic passing by on a freeway. The
electromagnetic field produced by an antenna can be constantly present when multiple tags
are expected continually. If constant interrogation is not required, a sensor device can
activate the field.
Often the antenna is packaged with the transceiver and decoder to become a reader
which can be configured either as a handheld or a fixed-mount device. The reader emits
radio waves in ranges of anywhere from one inch to 100 feet or more, depending upon its
power output and the radio frequency used. When an RFID tag passes through the
electromagnetic zone, it detects the reader's activation signal. The reader decodes the data
encoded in the tag's integrated circuit (silicon chip) and the data is passed to the host
computer for processing.
1.2.3 THE READER, or scanning device, also has its own antenna, which it uses to
communicate with the tag. Readers vary in size, weight, and power, and may be mobile or
stationary. Although anyone with access to the proper reader can scan an RFID tag, RFID
systems can employ authentication and encryption to prevent unauthorized reading of data.
“Reading” tags refers to the communication between the tag and reader via radio waves
operating at a certain frequency. In contrast to bar codes, one of RFID’s principal
distinctions is tags and readers can communicate with each other without being in each
other’s line-of-sight. Therefore, a reader can scan a tag without physically “seeing” it.
Further, RFID readers can process multiple items at one time, resulting in a much-increased
(again as compared to UPC codes) “speed of read.”
1.2.4 THE DATABASE, or other back-end logistics system, stores information about
RFID-tagged objects. Access to both a reader and its corresponding database are necessary
before information stored on an RFID tag can be obtained and understood. In order to
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interpret such data, RFID readers must be able to communicate with a database or other
computer program.
1.2.5 CONTROLLER, The controller is the interface between one or more antenna and the
device requesting information from or writing information to the RF tags. There are
controllers for interfacing antenna to PCs servers and networks. The selection of controller
and interface device will affect the antenna’s transmission speed. Some controllers can be
programmed to perform data translation and interrogation. This transfers some of data
processing load from the devices to the controllers.
1.2.6 RADIO FREQUENCY, Communication between RFID tags and readers is also
affected by the radio frequency used, which determines the speed of communications as
well as the distance from which tags can be read. Higher frequency typically means longer
read range. Low-frequency (“LF”) tags, which operate at less than 135 kilohertz (KHz), are
thus appropriate for short-range uses, like animal identification and anti-theft systems, such
as RFID-embedded automobile keys. Systems that operate at 13.56 megahertz (MHz) are
characterized as high frequency (“HF”). Both low-frequency and high-frequency tags can
be passive. Scanners can read multiple HF tags at once and at a faster rate than LF tags. A
key use of HF tags is in contactless “smart cards,” such as mass transit cards or building-
access badges.
The third frequency, Ultra-High Frequency (“UHF”), is contemplated for widespread
use by some major retailers, who are working with their suppliers to apply UHF tags to
cases and pallets of goods. These tags, which operate at around 900 MHz, can be read at
longer distances, which outside the laboratory environment range between three and
possibly fifteen feet. However, UHF tags are more sensitive to environmental factors like
water, which absorb the tag’s energy and thus block its ability to communicate with a
reader.
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Table 1- different frequency bands
Frequency
band
Typical RFID
frequencies
Characteristics Typical
Applications
low
30 – 300 KHz
125 – 134 kHz Short to medium read
range
Inexpensive
Low reading speed
Access control
Animal
identification
Inventory control
Car immobilizer
intermediate
3 – 30 MHz
13.56 MHz Short to medium read
range
Potentially inexpensive
Medium reading speed
Access control
Smarts cards
high
300MHz -3GHz
433 MHz / 2.45
GHz
Long read range
Expensive
Line of sight required
High reading speed
Railroad car
monitoring
Toll collection
systems
Although all RFID systems have these essential components, other variables affect
the use or set of applications for which a particular tag is appropriate. As discussed further
below, key factors include whether the tag used is “active” or “passive”; what radio
frequency is used; the size of the antennas attached to the chip and to the reader; what and
how much information can be stored on a tag; and whether the tag is “read/write” or “read-
only.” These factors affect the read ranges of the systems as well as the kind of object that
can usefully be tagged. They also impact the cost, which is an especially important
commercial consideration when tagging a large volume of items.
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Fig 1.2 – radio wave frequency spectrum
There are three types of RFID tags, differentiated by how they communicate and how
that communication is initiated:
Passive tags have no onboard power source – meaning no battery – and do not initiate
communication. A reader must first query a passive tag, sending electromagnetic waves that
form a magnetic field when they “couple” with the antenna on the RFID tag. Consistent
with any applicable authorization, authentication, and encryption, the tag will then respond
to the reader, sending via radio waves the data stored on it. Currently, depending on the size
of the antenna and the frequency, passive tags can be read, at least theoretically, from up to
thirty feet away. However, real-world environmental factors, such as wind and interference
from substances like water or metal, can reduce the actual read range for passive tags to ten
feet or less. Passive tags are already used for a wide array of applications, including
building-access cards, mass transit tickets, and, increasingly, tracking consumer products
through the supply chain.
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Semi-passive tags, like passive tags, do not initiate communication with readers, but they
do have batteries. This onboard power is used to operate the circuitry on the chip, storing
information such as ambient temperature. Semi-passive tags can be combined, for example,
with sensors to create “smart dust” – tiny wireless sensors that can monitor environmental
factors. A grocery chain might use smart dust to track energy use, or a vineyard to measure
incremental weather changes that could critically affect grapes.
Active tags can initiate communication and typically have onboard power. They can
communicate the longest distances – 100 or more feet. A familiar application of active tags
is for automatic toll payment systems.
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Table 2- passive tag V/s active tag
PASSIVE RFID ACTIVE RFID
POWER SOURCE External(reader provided) Internal (battery)
TAG READABILITY Only within the area covered
by the reader, typically up to
3 meters.
Can provide signals over an
extended range, typically up
to 100 meters..
ENERGIZATION A passive tag is energized
only when there is a reader
present.
An active tag is always
energized.
MAGNETIC
FIELD STRENGTH
High, since the tag draws
power from the
electromagnetic field
provided by the reader.
Low, since the tag emits
signals using internal battery
source.
SHELF LIFE Very high, ideally does not
expire over a life time.
Limited to about 5 years, the
life of a battery.
DATA STORAGE Limited data storage,
typically 128 bytes.
Can store larger amounts of
data.
COST Cheap Expensive
SIZE Smaller Slightly bulky(due to
battery)
The tag type used depends on many factors:8
• Distance between the tag and reader.
• Speed at which tags will pass the reader.
• Environmental obstructions between the tag and reader.
These factors define the requirements of the RFID system and hence the cost of
implementation and on-going support.
The data storage component of a tag typically supports one of the following read-
write capabilities; read-only, write once, or full read-write.
Read-only tags are loaded with data once, typically in the manufacturing process of the
RFID. In addition, this type of tag enables multiple read operations.
Write-once-read-many (WORM) chips enable the user to customize the chip with
information. Data can be loaded with a special write unit in the field that enables an entire
box of chips to be coded with the same data. These, however, are a one-time write operation
that requires a special RFID writing device.
Read-write tags allow repeated write and read operations to the tag. These are the most
expensive type of tags, but are also the most versatile.
.
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CHAPTER 2 – HISTORY OF RFID
It is generally said that the roots of radio frequency identification technology can be
traced back to World War II. The Germans, Japanese, Americans and British were all using
radar—which had been discovered in 1935 by Scottish physicist Sir Robert Alexander
Watson-Watt—to warn of approaching planes while they were still miles away. The
problem was there was no way to identify which planes belonged to the enemy and which
were a country’s own pilots returning from a mission. The Germans discovered that if pilots
rolled their planes as they returned to base, it would change the radio signal reflected back.
This crude method alerted the radar crew on the ground that these were German planes and
not allied aircraft (this is, essentially, the first passive RFID system).
An early published work exploring RFID is the landmark paper by Harry
Stockman, “Communication by Means of Reflected Power”. Stockman stated then that
“Evidently, considerable research and development work has to be done before the remain-
ing basic problems in reflected-power communication are solved, and before the field of
useful applications is explored.”
Under Watson-Watt, who headed a secret project, the British developed the first
active identify, friend or foe (IFF) system. They put a transmitter on each British plane.
When it received signals from radar stations on the ground, it began broadcasting a signal
back that identified the aircraft as friendly. RFID works on this same basic concept. A
signal is sent to a transponder, which wakes up and either reflects back a signal (passive
system) or broadcasts a signal (active system).
The 1960s were the prelude to the RFID explosion of the 1970s. R.F. Harrington
studied the electromagnetic theory related to RFID in his papers including “Theory of
Loaded Scatterers” in 1964. Inventors were busy with RFID-related inventions such as
Robert Richardson’s “Remotely activated radio frequency powered devices,” and J. H.
Vogelman’s “Passive data transmission techniques utilizing radar echoes.” Commercial
activities were beginning in the 1960s. Sensormatic and Checkpoint were founded in the
late 1960s. These companies, with others such as Knogo, developed electronic article
surveillance (EAS) equipment to counter the theft of merchandise. These types of systems
are often use 1-b tags; only the presence or absence of a tag could be detected, but the tags
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could be made inexpensively and provided effective antitheft measures. These types of
systems used either microwave (generation of harmonics using a semiconductor) or
inductive (resonant circuits) technology. EAS is arguably the first and most widespread
commercial use of RFID. Tags containing multiple bits were generally experimental in
nature and were built with discrete components. While single-bit EAS tags were small,
multi bit tags were the size of a loaf of bread, constrained in size by the dictates of the
circuitry.
A decade of further development of RFID theory and applications followed,
including the use of RFID by the U.S. Department of Agriculture for tracking the movement
of cows. In the 1970’s the very first commercial applications of the technology were
deployed, and in the 1980’s commercial exploitation of RFID technology started to
increase, led initially by small companies.
In the 1970s developers, inventors, companies, academic institutions, and
government laboratories were actively working on RFID, and notable advances were being
realized at research laboratories and academic institutions such as Los Alamos Scientific
Laboratory, North-western University, and the Microwave Institute Foundation in Sweden.
An early and important development was the Los Alamos work that was presented by
Alfred Koelle, Steven Depp, and Robert Freyman, “Short-Range Radio- Telemetry for
Electronic Identification Using Modulated Backscatter,” in 1975. This development
signalled the beginning of practical, completely passive tags with an operational range of
tens of meters. Large companies were also developing RFID technology, such as
Raytheon’s Raytag in 1973 and Richard Klensch of RCA developing an electronic
identification system in 1975. Research efforts continued as well. R.J. King authored a book
about microwave homodyne techniques in 1978. This book is an early compendium of
theory and practice used in backscatter RFID systems.
Tag technology had improved with reductions in size and improvements in
functionality. The key to these advancements was the use of low-voltage, low power CMOS
logic circuits. Tag memory utilized switches or wire bonds and had improved with use of
fusible link diode arrays by the end of the decade. The 1980s became the decade for full
implementation of RFID technology, though interests developed somewhat differently in
various parts of the world.
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The 1990s were a significant decade for RFID since it saw the wide scale
deployment of electronic toll collection in the United States and the installation of over 3
million RFID tags on rail cars in North America. Important deployments included several
innovations in electronic tolling. The world’s first open highway electronic tolling system
opened in Oklahoma in 1991, where vehicles could pass toll collection points at highway
speeds, unimpeded by a toll plaza or barriers and with video cameras for enforcement. The
first combined toll collection and traffic management system was installed in the Houston
area by the Harris County Toll Road Authority in 1992.
In the 1990’s, RFID became much more widely deployed. However, these
deployments were in vertical application areas, which resulted in a number of different
proprietary systems being developed by the different RFID solutions providers. Each of
these systems had slightly different characteristics (primarily relating to price and
performance) that made them suitable for different types of application. However, the
different systems were incompatible with each other – e.g. tags from one vendor would not
work with readers from another. This significantly limited adoption beyond the niche
vertical application areas – the interoperability needed for more widespread adoption could
not be achieved without a single standard interoperable specification for the operation of
RFID systems. Such standardisation was also needed to drive down costs.
The drive towards standardisation started in the late 1990’s.There were a number of
standardisation efforts, but the two successful projects were:
➜ The ISO 18000 series of standards that essentially specify how an RFID system should
communicate information between readers and tags
➜ the Auto-ID Centre specifications on all aspects of operation of an RFID asset tracking
system, which has subsequently been passed onto EAN.UCC (the custodians of the
common barcode) for international standardisation
The pace of developments in RFID continues to accelerate. The future looks very
promising for this technology. The full potential also requires advancements in other areas
as well such as development of applications software; careful development of privacy
policies and consideration of other legal aspects; development of supporting infrastructure
to design, install, and maintain RFID systems; and other such activities now that RFID has
truly entered the mainstream. At first glance, the concept of RFID and its application seems
simple and straightforward. But in reality, the contrary is true. RFID is a technology that 12
spans systems engineering, software development, circuit theory, antenna theory, radio