Radio-frequency identification (RFID)

Radio-frequency identification (RFID) is a type of wireless communication system used to uniquely identify objects or living things. RFID systems use elements known as tags and readers to facilitate the contactless exchange of information. Tags emit radio frequencies unique to each object or organism in the RFID system, which readers capture and use to identify and gather information about the tagged object or organism.

RFID tags and readers function as part of a three-component system comprised of an antenna, a transceiver, and a transponder. The antenna performs scanning functions, catching the radio frequencies emitted by tagged elements in the network and converting them into electricity, which generates signals that can be read as data. The transceiver, which combines a transmitter and a receiver into a single unit, and the antenna function together to make up the reader element of an RFID system. Antenna-transceiver systems are also known as RFID interrogators. The third networked component, the transponder, receives and responds to inbound signals. Transponders are embedded in RFID tags, facilitating exchanges with their counterpart readers.

Background

The foundations of contemporary RFID technology are rooted in World War II (1939–1945) when the militaries of both the Allied and Axis powers built on established continuous-wave technologies that both generated and transmitted detectable radio signals. These efforts led to the creation of radar, which uses radio waves to locate and identify distant objects within the radar system’s operational range. Early-generation RFID systems essentially combined the functions of radar with broadcasting technologies, as first proposed in a 1948 paper by the Swedish-born, United States-based scientist and inventor Harry Stockman (1905–1991). During the 1950s, researchers began to develop transponder networks known as “identification, friend, or foe” (IFF) systems, which were capable of operating across long ranges. Scientists went on to develop radar-powered passive data transmission and remote-activated radio-frequency devices during the 1960s, setting up major advancements in the evolving field of RFID technology.

In the 1970s, engineers, developers, and stakeholders from academia and both the public and private sectors worked to refine the rudimentary commercial RFID systems that had debuted during the previous decade. Researchers based at the Los Alamos National Laboratory in New Mexico unveiled a groundbreaking RFID system based on the concept of passive tagging, which was capable of operating at short range. As the 1970s advanced, RFID developers honed their focus on improving the capabilities and reducing the sizes of tagging technologies. By the 1980s, RFID had advanced to the point that it began making inroads in North America and Europe. In North America, RFID technologies were mainly used in the transportation sector and to regulate access to controlled or restricted locations. In Europe, RFID systems found their primary applications in the agricultural and industrial sectors, and they were also used in countries including France, Italy, Norway, Portugal, and Spain to improve the operational efficiency of toll-based roads and highways.

RFID continued to expand in the 1990s, with the increasingly widespread deployment of induction-based and microwave-based systems in an ever-broadening range of settings. Access control and electronic road toll collection continued to dominate RFID’s commercial applications, but novel uses based on the TIRIS system created by Texas Instruments also began to emerge. These included RFID-controlled fuel pumps, vehicle and user access networks, and gaming systems. The first international standards for RFID systems also debuted during the 1990s, when the European Committee for Standardization (CEN) created uniform specifications and operational criteria for the technology’s use in electronic toll collection. Agencies, including the International Organization for Standardization (ISO), Electronics Product Code Global Incorporated (EPCglobal), and the International Electrotechnical Commission (IEC), have since assumed responsibility for most RFID standardization protocols.

By the late 1990s, further technical improvements to RFID tagging circuitry resulted in significant increases in reliability and usability while continuing to reduce chip sizes and system costs. Additional standardization efforts emerged during the 2000s when the use of RFID technology began accelerating at a rapid pace. The RFID systems used in the 21st century combine principles and insights from fields ranging from network engineering and circuitry design to software development and encryption technology into a package defined by functional simplicity and ease of use.

Radio-frequency identification systems have evolved into three main categories: low-frequency, high-frequency, and ultra-high frequency (UHF). Low-frequency RFID technologies operate in a frequency spectrum ranging from 30 to 500 kilohertz (kHz), with 125 kHz serving as a common standard. They are used for short-range applications, with a maximum operational range of approximately 6 feet (1.83 meters). High-frequency RFID systems work in the 3–30 megahertz (MHz) range, though most use a frequency of 13.56 MHz. Their operational ranges are similar to those of low-frequency systems, with the primary differences between low-frequency and higher-frequency systems relating to technical aspects of their respective functionalities. Low-frequency RFID systems read and transmit data at slower rates, but they can also send and receive signals in all directions with greater strength and reliability. UHF systems operate at 300–960 MHz and have significantly upgraded ranges of 25 feet (7.62 meters) or more. A fourth system type, microwave RFID, operates at 2.45 gigahertz (GHz) and can function over distances exceeding 30 feet (9.14 meters).

The tags used in RFID networks come in two main varieties: active and passive. Active RFID tags have their own internal power source. Batteries supply the power required by most active RFID tags. Passive tags draw their power from the RFID antenna linked in the system, which activates a tiny receiver embedded in the tag to stimulate electrical current. Passive tagging systems offer superior ease of maintenance as individual tags do not need to be replaced when their power source runs out, but active tags are capable of transmitting signals over longer ranges.

Some RFID systems also integrate a technology known as smart labeling. Smart labels are generally used in consumer products and consist of an RFID tag built into a barcode label. RFID readers and barcode readers can both extract the product information attached to a smart label, improving the technology’s versatility compared to standalone RFID tagging or barcode labeling.

Overview

RFID has met with an increasingly broad scope of applications as the costs of the underlying technologies have decreased while their functionality has increased. Most use cases involving organisms apply to pets and livestock: RFID-powered tags can be used to identify and track lost or runaway pets, while livestock-oriented systems are mainly used to track individual animals. With respect to objects and consumer products, RFID is mainly used for inventory control, inventory management, equipment tracking, cargo shipping, manufacturing, and other applications that demand the contact-free tracking of uniquely identifiable goods. Radio-frequency identification has also become a common feature of supply chain management and logistics, where it is mainly used to make individual products or items more visible and trackable as they make their way through supply chains, which improves the efficiency of product distribution networks. RFID technologies have also made inroads in other consumer-oriented fields, including loss prevention and contactless card-based payment systems.

Increasingly, RFID technologies are also being used in place of barcodes, especially in the realm of inventory management. In this respect, RFID tags offer several functional improvements over barcodes: objects do not need to come into individual contact with a scanner or reader to be uniquely identified, and RFID systems can also detect and identify objects at greater distances than barcode readers. They also have much shorter average read times than barcode systems and can be linked with networked inventory management platforms to facilitate the real-time updating of relevant tracking information.

Radio-frequency identification has also been widely adopted by healthcare institutions, where its applications include inventory and equipment management, personnel access control and location tracking, and systems designed to administer the correct devices and medications to patients. RFID technologies are also used to detect falls out of bed and patients who leave their beds or rooms without authorization. The US Food and Drug Administration (FDA) also notes that healthcare institutions have deployed RFID technology to combat the counterfeiting of both medical devices and pharmaceutical drugs. In addition, radio-frequency identification technologies can be used to transmit and record data for use in electronic patient records. However, this use case has generated controversy due to its privacy implications and the possibility of sensitive medical information being intercepted by an unauthorized third party.

Many points of contact link RFID technology and the Internet of Things (IoT), which arranges everyday objects and consumer products in networked systems to facilitate advanced and remotely activated functionality. Expert observers generally consider RFID an important precondition for building a fully optimized IoT, as the ubiquitous RFID tagging of everyday products and objects would make it possible for internet-connected computer systems to identify, inventory, monitor, track, and activate practically any linked item. Some theoretical IoT models also propose to include tagged people in their networks, which would create unprecedented possibilities in the security and surveillance arenas.

From a technical standpoint, RFID technology suffers from two main problems: reader collision and tag collision. Reader collision is associated with systems that use multiple readers, and it occurs when a signal emanating from one reader interferes or is interfered with by a signal from another networked reader. The problem of reader collision can be remedied by implementing a specialized protocol that prompts linked RFID tags to transmit their signals to a single, specified reader. However, its implementation adds complexity to the system while also increasing costs. Tag collision is similar to reader collision, except that the issue originates with tagged objects or organisms bombarding and overwhelming a reader with signal relays. System designers and operators can avoid tag collision by installing readers configured to read only one piece of tagging information at a time. This can, however, reduce performance efficiency by increasing the overall amount of time a reader or reader network requires to collect all pertinent tagging data.

When animals and people are connected to RFID systems via tags, the tagging elements must be embedded in an object worn on their bodies or physically implanted within them. The FDA has stated that it has not received any corroborated reports of adverse health events arising from such use of RFID technology, and experts believe the risk of such adverse events is very low. However, the FDA does acknowledge that RFID tags have the potential to interact with electronic medical implements such as implantable cardioverter defibrillators (ICDs) and pacemakers, which may pose health risks in certain contexts.

Radio-frequency identification technology has also drawn a great deal of scrutiny on privacy grounds for both its established and potential uses. Some such concerns focus on RFID-enabled passports, which have enhanced machine-readable capabilities that allow customs and immigration officials to screen travelers more thoroughly and efficiently. The RFID chips commonly used in these passports are unique in that they are among the only ones on the consumer market with built-in encryption capabilities. These chips are governed by basic access control (BAC) mechanisms, which offer elementary encryption functions that serve to validate the passport by performing a series of checks against the unique data contained in each document. However, critics note that the level of encryption protection used in RFID-enabled passports is far less stringent than the standards that apply to other sensitive transactions, such as internet-based financial services and commerce. Furthermore, the authentication keys generated by BAC systems do not change over the course of the passport’s validity period, making it theoretically possible for any individual or system with access to a passport’s unique key to read the data it contains without the bearer’s authorization or knowledge.

Broader security and privacy concerns also extend to the potential expansion of RFID technology into other areas of human endeavor. Such concerns are generally rooted in the ability of any individual with the appropriate RFID reader to intercept and harvest the signals sent by RFID tags—an issue that has already impacted supply chain and inventory management applications. This potentially allows third parties to tie RFID tags with unique identifiers, such as serial numbers, to particular individuals, creating the possibility of novel and highly invasive forms of consumer surveillance. Rogue actors can perform such deeds without the knowledge or consent of the targeted party, stoking concern over RFID’s suitability for highly sensitive military and medical applications.

A similar set of concerns applies to theoretical use cases in which certain individuals or population groups could knowingly or unknowingly be equipped with RFID tags in environments featuring a high density of compatible readers. This could enable intrusive levels of monitoring and surveillance, potentially on a mass or global scale.

Bibliography

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