Radio frequency identification (RFID) is a form of wireless communication that uses radio waves to identify and track objects. RFID takes the barcoding concept and updates it to fit expectations for technology in the digital age by providing quick and easy ways to:
–Uniquely identify an individual item beyond just its product type
–Identify items without direct line-of-sight
–Identify up to 1,000s of items simultaneously
–Identify items within a vicinity of between a few centimeters to several meters
An RFID system has readers and tags that use radio signals to communicate with each other. RFID tags are so small, and require so little power, that the power of the radio waves themselves is enough to store information and exchange data with readers, no batteries needed. This makes it easy and cheap to apply tags to all kinds of things that people might want to identify or track.
Why Use RFID?
RFID technology has the capability to increase safety and overall user experience for consumers of almost any physical product, and also revolutionize the way companies do business. As the most flexible auto-identification technology, RFID can be used to track and monitor the physical world automatically and with extreme accuracy.
RFID can tell you what an object is, where it is, its condition, and anything other information about an object that can be digitized, which is why it is integral to the development of the Internet of Things—a globally interconnected web of objects allowing the physical world itself to become an information system, automatically sensing what is happening, sharing related data, and responding.
RFID use is increasing rapidly with the capability to “tag” any item with an inexpensive communications chip and then read that tag with a reader. Endless applications range from supply chain management to asset tracking to authentication of frequently counterfeited pharmaceuticals. Applications are limited, in fact, only by the imagination of the user.
– Inventory automation and asset-tracking in healthcare, manufacturing, retail, and business sectors
– Identify the source of products, enabling intelligent recall of defective or dangerous items, such as tainted foods, defective toys, and expired or –compromised medication
– Prevent use of counterfeit products in the supply chain
– Improve shopping experience for consumers, with fewer out-of-stock items and easier returns
– Provide visibility into the supply chain, yielding a more efficient distribution channel and reduced business costs
– Decrease business revenue lost to theft or inaccurate accounting of goods
– Improve civilian security through better cargo monitoring at ports
– Remotely lock, unlock and configure electronic devices
– Enable access control of certain areas or devices
– Whatever the application, RFID has the potential to increase efficiency of operations, improve asset visibility and traceability, decrease reliance on manual processes, reduce operations costs, and provide useful data for business analytics.
In a basic RFID system, every item being tracked has a tag attached to it. These tags are made from a tiny tag-chip, or integrated circuit (IC), that is connected to an antenna and built into a variety of tags including apparel hang tags, labels, and security tags, as well as a wide range of industrial asset tags. The tag chip contains memory which stores the product’s electronic product code (EPC) and other variable information so that it can be read and tracked by RFID readers anywhere.
An RFID reader is a fixed or mobile network connected device with an antenna that sends power as well as data and commands to the tags. The RFID reader acts like an access point for RFID tagged items so that the tags’ data can be made available to business applications.
An RFID tag is comprised of an integrated circuit (called an IC or chip) attached to an antenna that has been printed, etched, stamped or vapor-deposited onto a mount which is often a paper substrate or PolyEthylene Therephtalate (PET). The chip and antenna combo, called an inlay, is then converted or sandwiched between a printed label and its adhesive backing or inserted into a more durable structure.
The tag’s chip, or integrated circuit (IC), delivers performance, memory and extended features to the tag. The chip is pre-programmed with a tag identifier (TID), a unique serial number assigned by the chip manufacturer, and includes a memory bank to store the items’ unique tracking identifier (called an electronic product code or EPC).
Tag antennas collect energy and channel it to the chip to turn it on. Generally, the larger the tag antenna’s area, the more energy it collects and channels toward the tag chip, and the greater its read range will be.
There is no perfect antenna for all applications. Each application requires different antenna specifications. Some tags might be optimized for a particular frequency band, while others might be tuned for being attached to materials that may not normally work well for wireless communication (certain liquids and metals, for example). Antennas can be made from a variety of materials; they can be printed, etched, or stamped with conductive ink, or even vapor deposited onto labels.
Tags that have only a single antenna are not as reliable as tags with multiple antennas. With a single antenna, a tag’s orientation can result in “dead zones”, or areas on the tag where incoming signals cannot be easily harvested to provide sufficient energy to power on the chip and communicate with the reader. A tag with dual antennas is able to eliminate these dead zones and increase its readability but requires a specialized chip.
An RFID reader, also known as an interrogator, is the connection between the tag data and the enterprise system software that uses the information. The reader communicates with tags that are within its range of operation, performing any number of tasks including simple continuous inventorying, searching for tags that meet certain criteria, writing (or encoding) to selected tags, etc.
The reader uses an attached antenna to capture data from tags. It then passes the data to a computer for processing. There are many different sizes and types of RFID readers. Readers can be fixed in a position in a store or factory, integrated into a mobile device such as a portable handheld scanner, or embedded in electronic equipment or devices, and in vehicles.
RFID readers and reader antennas work together to read tags. Reader antennas convert electrical current into electromagnetic waves that are then radiated into space where they can be received by a tag antenna and converted back to electrical current. Just like tag antennas, there is a large variety of reader antennas and optimal antenna selection varies according to the solution’s specific application and environment.
The two most common antenna types are linear- and circular-polarized antennas. Antennas that radiate linear electric fields have long ranges, and high levels of power that enable their signals to penetrate through different materials to read tags. Linear antennas are sensitive to tag orientation; depending on the tag angle or placement, linear antennas can have a difficult time reading tags. Conversely, antennas that radiate circular fields are less sensitive to orientation, but are not able to deliver as much power as linear antennas.
Choice of antenna is also determined by the distance between the RFID reader and the tags that it needs to read. This distance is called read range. Reader antennas operate in either a “near-field” (short range) or “far-field” (long range). In near-field applications, the read range is less than 30 cm and the antenna uses magnetic coupling so the reader and tag can transfer power. In near-field systems, the readability of the tags is not affected by the presence of dielectrics such as water and metal in the field.
In far-field applications, the range between the tag and reader is greater than 30 cm and can be up to several tens of meters. Far-field antennas utilize electromagnetic coupling and dielectrics can weaken communication between the reader and tags.
Creating an RFID Solution
Deploying an RFID system necessitates multiple actors and many different components. Typically, installing a system requires basic hardware-including tag chips, tag antennas, readers, and reader antennas-as well as reader control and application software, and solution providers to put it all together. When all of these components come together, an infinite number of creative applications are possible. RFID system applications can help improve the quality of business operations, inventory and customer experience in a variety of industries.
The different types of RFID systems
RFID systems can be broken down by the frequency band within which they operate: low frequency, high frequency, and ultra-high frequency. There are also two broad categories of RFID systems-passive and active. In the sections below we will explore the frequencies and types of RFID systems.
Frequency refers to the size of the radio waves used to communicate between RFID system components. RFID systems throughout the world operate in low frequency (LF), high frequency (HF) and ultra-high frequency (UHF) bands. Radio waves behave differently at each of these frequencies with advantages and disadvantages associated with using each frequency band.
If an RFID system operates at a lower frequency, it has a shorter read range and slower data read rate, but increased capabilities for reading near or on metal or liquid surfaces. If a system operates at a higher frequency, it generally has faster data transfer rates and longer read ranges than lower frequency systems, but more sensitivity to radio wave interference caused by liquids and metals in the environment.
The LF band covers frequencies from 30 KHz to 300 KHz. Typically LF RFID systems operate at 125 KHz, although there are some that operate at 134 KHz. This frequency band provides a short read range of 10 cm, and has slower read speed than the higher frequencies, but is not very sensitive to radio wave interference.
LF RFID applications include access control and livestock tracking.
Standards for LF animal-tracking systems are defined in ISO 14223, and ISO/IEC 18000-2. The LF spectrum is not considered a truly global application because of slight differences in frequency and power levels throughout the world.
The HF band ranges from 3 to 30 MHz. Most HF RFID systems operate at 13.56 MHz with read ranges between 10 cm and 1 m. HF systems experience moderate sensitivity to interference.
HF RFID is commonly used for ticketing, payment, and data transfer applications.
There are several HF RFID standards in place, such as the ISO 15693 standard for tracking items, and the ECMA-340 and ISO/IEC 18092 standards for Near Field Communication (NFC), a shortrange technology that is commonly used for data exchange between devices. Other HF standards include the ISO/IEC 14443 A and ISO/IEC 14443 standards for MIFARE technology, which used in smart cards and proximity cards, and the JIS X 6319-4 for FeliCa, which is a smart card system commonly used in electronic money cards.
The UHF frequency band covers the range from 300 MHz to 3 GHz. Systems complying with the UHF Gen2 standard for RFID use the 860 to 960 MHz band. While there is some variance in frequency from region to region, UHF Gen2 RFID systems in most countries operate between 900 and 915 MHz.
The read range of passive UHF systems can be as long as 12 m, and UHF RFID has a faster data transfer rate than LF or HF. UHF RFID is the most sensitive to interference, but many UHF product manufacturers have found ways of designing tags, antennas, and readers to keep performance high even in difficult environments. Passive UHF tags are easier and cheaper to manufacture than LF and HF tags.
UHF RFID is used in a wide variety of applications, ranging from retail inventory management, to pharmaceutical anti-counterfeiting, to wireless device configuration. The bulk of new RFID projects are using UHF opposed to LF or HF, making UHF the fastest growing segment of the RFID market.
The UHF frequency band is regulated by a single global standard called the ECPglobal Gen2 (ISO 18000-6C) UHF standard.
Active RFID Systems
In active RFID systems, tags have their own transmitter and power source. Usually, the power source is a battery. Active tags broadcast their own signal to transmit the information stored on their microchips.
Active RFID systems typically operate in the ultra-high frequency (UHF) band and offer a range of up to 100 m. In general, active tags are used on large objects, such as rail cars, big reusable containers, and other assets that need to be tracked over long distances.
There are two main types of active tags: transponders and beacons. Transponders are “woken up” when they receive a radio signal from a reader, and then power on and respond by transmitting a signal back. Because transponders do not actively radiate radio waves until they receive a reader signal, they conserve battery life.
Beacons are used in most real-time locating systems (RTLS), in order to track the precise location of an asset continuously. Unlike transponders, beacons are not powered on by the reader’s signal. Instead, they emit signals at pre-set intervals. Depending on the level of locating accuracy required, beacons can be set to emit signals every few seconds, or once a day. Each beacon’s signal is received by reader antennas that are positioned around the perimeter of the area being monitored, and communicates the tag’s ID information and position.
Passive RFID Systems
In passive RFID systems, the reader and reader antenna send a radio signal to the tag. The RFID tag then uses the transmitted signal to power on, and reflect energy back to the reader.
Passive RFID systems can operate in the low frequency (LF), high frequency (HF) or ultra-high frequency (UHF) radio bands. As passive system ranges are limited by the power of the tag’s backscatter (the radio signal reflected from the tag back to the reader), they are typically less than 10 m. Because passive tags do not require a power source or transmitter, and only require a tag chip and antenna, they are cheaper, smaller, and easier to manufacture than active tags.
Passive tags can be packaged in many different ways, depending on the specific RFID application requirements. For instance, they may be mounted on a substrate, or sandwiched between an adhesive layer and a paper label to create smart RFID labels. Passive tags may also be embedded in a variety of devices or packages to make the tag resistant to extreme temperatures or harsh chemicals.
Passive RFID solutions are useful for many applications, and are commonly deployed to track goods in the supply chain, to inventory assets in the retail industry, to authenticate products such as pharmaceuticals, and to embed RFID capability in a variety of devices. Passive RFID can even be used in warehouses and distribution centers, in spite of its shorter range, by setting up readers at choke points to monitor asset movement.
Battery-Assisted Passive (BAP) Systems
A Battery-Assisted Passive RFID tag is a type of passive tag which incorporates a crucial active tag feature. While most passive RFID tags use the energy from the RFID reader’s signal to power on the tag’s chip and backscatter to the reader, BAP tags use an integrated power source (usually a battery) to power on the chip, so all of the captured energy from the reader can be used for backscatter. Unlike transponders, BAP tags do not have their own transmitters.
RFID standards are guidelines or specifications for all RFID products. Standards provide guidelines about how RFID systems work, what frequencies they operate at, how data is transferred, and how communication works between the reader and the tag.
Why are RFID standards important?
RFID standards help ensure that RFID products are interoperable, regardless of the vendor or user. They also provide guidelines by which companies can develop complementary products, such as different types of tags, readers, software, and accessories. Additionally, standards help broaden markets and increase competition within the industry, which brings the prices of standardized RFID products down. RFID standards also help increase widespread confidence in the technology.
Who sets RFID standards?
Standards are developed and issued by industry-specific, national, regional, and global bodies. The more global the standard is, the more bodies are involved in its development. International organizations that issue RFID-related standards include EPCglobal (a GS1 venture), the International Electrotechnical Commission (IEC), the International Standards Organization (ISO), and the Joint Technical Committee (JTC 1), a committee formed by ISO and IEC. Regional regulatory entities that govern the use of RFID include the Federal Communication Commission (FCC), which is in charge of the United States, the European Telecommunications Standards Institute (ETSI), which operates in Europe. Other regions have their own regulatory entities.
Organizations that oversee RFID standards for specific industries include the Association of American Railroads (AAR), the Automotive Industry Standards Group (AIAG), the American Trucking Associations (ATA), and the International Air Transport Association (IATA). Additionally, the GS1 VICS Item Level RFID Initiative (VILRI) oversees standards around item-level tagging and the use of RFID technology throughout the retail supply chain.
What are the existing RFID standards?
Active RFID, passive LF RFID, passive HF RFID, and passive UHF RFID all have their own unique standards governing their associated products. See The Different Types of RFID Systems for more information.
Passive UHF RFID is currently the only type of RFID to be regulated by a single global standard. This standard is called EPCglobal UHF Gen 2 V1, or just UHF Gen 2. UHF Gen 2 defines the communications protocol for a passive backscatter, reader-talks-first radio frequency identification (RFID) system operating in the 860 MHz – 960 MHz frequency range. EPCglobal certification testing includes conformance testing, which ensures that RFID products are compliant with the UHF Gen2 standard, and interoperability testing, which makes sure that all aspects of the tagreader interface are properly designed to interoperate seamlessly with other Gen 2 certified products. While most passive RFID tags use the energy from the RFID reader’s signal to power on the tag’s integrated circuit (IC) and backscatter to the reader, BAP tags use an integrated power source (usually a battery) to power on the IC, so all of the captured energy from the reader can be used for backscatter. Unlike transponders, BAP tags do not have their own transmitters.
An update to the UHF Gen 2 standard, called UHF Gen 2 V2, or just G2, is in the process of being ratified. This new standard builds on the original V1 standard, but ensures that future RFID communications have more complex and powerful security options to protect data and prevent tag counterfeiting.
Under the G2 standard, the user is able to hide all, part, or none of the tag’s memory. Depending on what the reader’s access privileges are, and its proximity to the tag, the reader’s ability to access and/or modify tag data varies. This prevents tag data theft or tampering.
The G2 standards also establishes an anticounterfeiting measure that involves cryptographically authenticating tags. UHF Gen2 V1 tags send static replies back to the reader, making it easy for cloners to create counterfeit tags. Under G2 standards, each time a reader sends a signal to a tag it sends a different secret number and the tag computes a reply specific to that interaction.
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