How does RFID technology work?
Radio frequency identification technology is an automatic way to collect product,
place, time or transaction data quickly and easily without human intervention or
An RFID system comprises a reader (or interrogator), its associated antenna and the
transponders (Tags/ RFID Cards) that carry the data.
The reader transmits a radio signal, through its antenna, that the tag receives via its
own antenna. The tag will briefly converse with the reader for verification and the
exchange of data. Once the reader receives that data, it can be sent to a controlling
computer for processing and management.
An RFID tag consists of a microchip attached to an antenna. RFID tags are
developed using a frequency according to the needs of the system including read
range and the environment in which the tag will be read.
“Active Tags” are RFID tags that have their own independent power source via a
battery that is either internal with the tag itself or external that it shares with other
resources such as a car battery to supply its required voltage. This type of tag allows
for greater Read/Write distance capabilities but is generally larger in physical size
and is a little more expensive than Passive Tags. Typically an active tag can transmit
an effective RF signal up to 300 feet indoors and up to 1000 feet outdoors. Life
expectancy varies depending on power supply and usage.
“Passive Tags” are RFID tags that have no independent power source and get all its
power from the transceiver directly when activated. This type of tag is also much
smaller, and less expensive, which gives it a wider range of applications in which its
size and shape can be utilized. Effective range is less than 10 feet. With no battery
source to deal with, passive tags ideally have an unlimited life span.
An RFID reader usually connected to a personal computer serves the same purpose
as a barcode scanner. It can also be battery-powered to allow mobile transactions
with RFID tags. The RFID reader handles the communication between the
Information System and the RFID tag.
An RFID antenna connected to the RFID reader can be of various size and
structure, depending on the communication distance required for a given system’s
performance. The antenna activates the RFID tag and transfers data by emitting
An RFID station made up of an RFID reader and an antenna. It can read
information stored into the RFID tag and also update this RFID tag with new
information. It generally holds application software specifically designed for the
required task. RFID stations may be mounted in arrays around transfer points in
industrial processes to automatically track assets as they are moving through the
RFID Frequency ranges
Three frequency ranges are generally distinguished for RFID systems, low,
intermediate (medium) and high. The following table summarizes these three
frequency ranges, along with the typical system characteristics and examples of
major areas of application.
Frequency Band Characteristics Typical Applications
Low Short to medium read range Access control
100-500 kHz Inexpensive Animal identification
Low reading speed Inventory control
Intermediate Short to medium read range Access control
10-15 MHz potentially inexpensive Smart cards
medium reading speed
High Long read range Railroad car monitoring
850-950 MHz High reading speed Toll collection systems
2.4-5.8 GHz Line of sight required
A degree of uniformity is being sought for carrier frequency usage, through three
regulatory areas, Europe and Africa (Region 1), North and South America (Region 2)
and Far East and Australasia (Region 3). Each country manages their frequency
allocations within the guidelines set out by the three regions. Unfortunately, there
has been little or no consistency over time with the allocation of frequency, and so
there are very few frequencies that are available on a global basis for the
technology. This will change with time, as countries are required to try to achieve
some uniformity by the year 2010.
Three carrier frequencies receiving early attention as representative of the low,
intermediate, and high ranges are 125kHz, 13.56 MHz and 2.45 GHz. However,
there are eight frequency bands in use around the world, for RFID applications. Not
all of the countries in the world have access to all of the frequency bands listed
above, as some countries have assigned these bands to other users. Within each
country and within each frequency range there are specific regulations that govern
the use of the frequency. These regulations may apply to power levels and
interference as well as frequency tolerances. In the less than 135kHz, a wide range
of products is available to suit a range of applications, including animal tagging,
access control and track and trace ability. Transponder systems, which operate in
this band, do not need to be licensed in many countries.
RFID is a “Hot Issue” because of Wal-Mart’s Mandate
Wal-Mart will require all pallets and cases to have RFID tags based on the Class 1,
version 2 specification of the Electronic Product Code (EPC); it is being developed
under the auspices of EPCglobal, a joint venture between the Uniform Code Council
and EAN International, charged with commercializing EPC technology. The tag will
carry a 96-bit serial number and be field-programmable. Class 1 or Class 0 tags
are acceptable, but Wal-Mart would like to see suppliers move to Class 1
version 2 as soon as the specification is ready.
What is the Electro nic Product Code(EPC) ?
The Auto-ID Center has proposed a new Electronic Product Code as the next
standard for identifying products. Our goal is not to replace existing bar code
standards, but rather to create a migration path for companies to move from
established standards for bar codes to the new EPC. To encourage this evolution, we
have adopted the basic structures of the Global Trade Item Number (GTIN), an
umbrella group under which all existing bar codes fall. There's no guarantee that the
world will adopt the EPC, but our proposal already has the support of the Uniform
Code Council and EAN International, the two main bodies that oversee international
bar code standards. We're also working with other national and international trade
groups and standard bodies.
EPC code structure
The EPC is a number made up of a header and three sets of data, as shown in the
above figure. The header identifies the EPC's version number - this allows for
different lengths or types of EPC later on. The second part of the number identifies
the EPC Manager - most likely the manufacturer of the product the EPC is attached
to - for example 'The Coca-Cola Company'. The third, called object class, refers to
the exact type of product, most often the Stock Keeping Unit - for example 'Diet
Coke 330 ml can, US version'. The fourth is the serial number, unique to the item -
this tells us exactly which 330 ml can of Diet Coke we are referring to. This makes it
possible, for example, to quickly find products that might be nearing their expiration
Example of EPC 01.115A1D7.28A1E6.421CBA30A
01 Version of EPC (8 bit header)
115A1D7 Manufacturer Identifier
28 bits (> 268 million possible manufacturers
28A1E6 Product Identifier
24 bits (> 16 million possible products per
421CBA30A Item Serial Number
36 bits (> 68 billion possible unique items per
EPC Compliant tag classes
The difference between Class 0 and 1 is in the data structure and
operation. Class 0 tags are read only. Class 1 tags are one-time writeable.
The EPC standards call for 5 classes of tags overtime. The following table outlines
the roadmap for the EPC tag class type:
Class Type Operation
0 Read Only
1 Write Once, Read Many
2 Read / Write
3 Read / Write Battery Enhanced for Long Range
4 Read / Write Active Transmitter
Widely used RFID ISO Standards in use today
ISO 14443 for “proximity” cards and ISO 15693 for “vicinity” cards, both
recommend 13.56 MHz as its carrier frequency. These standards feature a thinner
card, higher memory space availability and allow numerous cards in the field to be
read almost simultaneously using anti-collision, bit masking and time slot protocols.
ISO 14443 proximity cards offer a maximum range of only a few inches. It is
primarily utilized for financial transactions such as automatic fare collection, bank-
card activity and high security applications. These applications prefer a very limited
range for security.
ISO 15693 vicinity cards offer a maximum usable range of out to 28 inches from a
single antenna or as much as 4 feet using multiple antenna elements and a high
performance reader system.
ISO Standards for RFID Air interface competing with EPC.
18000 – 1 Part 1 – Generic Parameters for Air Interface
Communication for Globally Accepted Frequencies
18000 – 2 Part 2 – Parameters for Air Interface
Communications below 135 KHz
18000 – 3 Part 3 – Parameters for Air Interface
Communications at 13.56 MHz
18000 – 4 Part 4 – Parameters for Air Interface
Communications at 2.45 GHz
18000 – 5 Part 5 – Parameters for Air Interface
Communications at 5.8 GHz
18000 – 6* Part 6 - Parameters for Air Interface
Communications at 860 – 930 MHz
18000 – 7** Part 7 - Parameters for Air Interface
Communications at 433.92 MHz
Effective read/write ranges of readers
Reading large objects whose tag may be positioned on opposite side.
Proximity – distinguish specific object from other objects on either side.
Reading mixed-case pallets fast enough and accurate.
Materials of the object or around the object (metal, liquid) can affect readability.
Currently 20-30% error rate in reading tags.
Standards ? - EPC , ISO, proprietary
There are actually hundreds of standards related to RFID being developed or
modified by scores of national and international standards bodies. Examples include
the format and content of the codes placed on the tags, the protocols and
frequencies that will be used by the tags and readers to transmit the data, the
security and tamper-resistance of tags on packaging and freight containers, and
applications use standards. Until these standards are finalized, there will
be a risk of non-compliance associated with any solution implemented.
Wal-Mart – supports EPC
DOD – Wants to support EPC but using ISO standard for air interface
Although the costs for tags and readers continue to come down, implementing an
RFID solution is still a very expensive venture. AMR Research estimates that a typical
consumer goods company shipping 50 million cases per year will spend $13 million
to $23 million to deploy RFID to meet Wal-Mart’s requirements.
Besides the cost of the tags for every pallet, case or item to be tracked, there are
the costs of the readers at every identification point, the software development and
implementation costs for use of the information, and the supporting infrastructure
The biggest risk at this time, however, is that a company will incur these substantial
costs only to find out that the solution deployed does not meet future standards or
that the technology or vendor used for the deployment has not survived the
inevitable shakeout of early contenders in this emerging field. To protect against this
possibility, companies should select technologies and vendors that are adaptable to
emerging standards and protocols.
There has already been significant backlash from consumers over announcements by
Wal-Mart, Gillette and Bennetton that they would use item -level RFID tagging. All
three companies have had to pull back from these initiatives as a result. Privacy has
always been a strong American value and concerns over the perceived invasion of
privacy these announcements incited, whether justified or not, is a factor that must
be considered in any RFID rollout.
Possible 4-phase RFID rollout approach
Prove the concept of RFID as a viable technology within the enterprise.
Test the selected technologies and communications to insure they work and will be
compatible with the current infrastructure.
Determine the impact on current distribution operations.
Scope the costs and expected ROI of the initiative.
Develop a project plan for rollout of future phases.
All Wal-Mart suppliers should make compliance with their directive a first priority
after the completion of a successful pilot phase. Given the amount of revenue many
suppliers receive from Wal-Mart business, companies will want to make sure they
have the time and resources needed to achieve compliance by the specified deadline.
Because compliance is a condition of doing business rather than a cost saving
measure, companies will want to begin extending their RFID applications to take
advantage of potential efficiency and productivity gains once they are certain the
compliance piece is working properly. As with the compliance phase, however, any
additional RFID applications will have to work side-by-side with existing applications
and infrastructure for an extended period.
The basic assumption of the transition phase is that companies have huge
investments in systems, equipment and communications that they cannot rip out to
start over with RFID. It would be cost prohibitive. Nor would it make sense to
introduce entirely new RFID-based processes across the warehouse all at one time.
There is also the reality that RFID technology is not mature enough to accomplish all
of the processing envisioned for the future potential benefits. The only logical
solution, therefore, is to deploy RFID technology one step at a time, focusing first on
those applications for which the technology is ready and which provide the greatest
return on investment. It would also be least disruptive to other operations to
concentrate on self-contained functions such as receiving or trailer loading. Changing
processes in these areas will have minimal impact on other functions, whereas
introducing RFID into picking or other wide-area functions could have significant
negative impact on operations.
As RFID rollout to one function is successfully completed, the next RFID application
can be implemented. The plan for which applications are to be implemented and
their sequencing will depend on the needs of each organization and the ROI each will
produce. The guiding factors for selecting and sequencing applications should be the
expected ROI, technology availability, customer requirements, and the least
disruption to other operations. One thing is clear for this staged RFID deployment,
existing systems will need to be modified to permit seamless side-by side operations
with existing processes. Warehouse management and labor management systems
will be most affected by this. They will have to support concurrent data capture from
RFID and RF or manual sources and be able to process this data interchangeably for
downstream processing. The positive side of this duality of operations is that RFID
operations can be easily phased in with traditional RF and manual operations without
significant disruption. This allows the investment and risks of new initiatives to be
balanced with expected ROI and advances in the technology.
Scan Free Phase
The ultimate goal for RFID technology is to transform supply chain operations. Often
this is defined as replacing current RF processes with more efficient scan free
processes and eliminating many manual tasks. However, the real value will come
from fundamentally changing the way warehouses and distribution centers receive,
store, move and ship product. What RFID has the potential to do is remove the
human element from locating, tracking, recording and transmitting information about
objects in the warehouse. Those objects could be pallets, cases or individual items,
but could also be forklifts, pallet jacks, rack locations or other equipment.
Currently tags are not created based upon a single standard.
Air interface protocol used between the reader and the tag is not a single standard..
Protocol between the reader and the host server is not a single standard and in fact
The middleware is not based upon a single standard.
The Wal-Mart desired direction Class1Version2 tag will probably require hardware
change to what is available today(specifically readers).
Although the potential benefits of RFID could be significant, there are substantial
technical, financial and psychological challenges that must be addressed before the
promise of RFID can be fully realized. This will take time as well as being proactive
especially towards consumer acceptability. As a result, companies should neither
believe all of the current hype in the marketplace, nor rush to implement applications
before the technology and financial justification have been proven. However, neither
can companies afford to wait until all risks have been eliminated before joining this
supply chain revolution. Those who begin now with prudent investments will gain
competitive advantage over those who hold back. The CPG companies are initially
going to bear a significant cost to continue to do business. The large retailers are
going to be in a better position to get a ROI because they do not have to invest in
the technology to generate the tags nor the actual cost of the tags.
Rod Harrison works at Cornerstone Solutions. He can be reached at 260-496-8259.
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