In this blog post, we’ll explore how the transit cards we use every day work, as well as the characteristics, applications, and limitations of RFID technology.
Transportation Cards and RFID in Everyday Life
An old energy drink commercial featured a woman who, after receiving a call from her boss saying he was looking for her, hurriedly boarded a bus and inserted her cell phone into the fare box instead of money. While the ad humorously conveyed the message to “snap out of it,” such mistakes are rarely seen today since most people use transportation cards. Instead, a more common sight these days is people accidentally holding their cell phones up to the transit card reader instead of their transit card.
Today, transit cards are widely used in South Korea, and they come in various forms, such as plastic cards, smartphones, and smartwatches. So, how do these transit cards actually work? You don’t swipe them like a credit card, nor do you insert them like an ATM card. They are recognized simply by bringing them close to the reader and can even be used while still inside a wallet or bag. The technology that makes this possible is RFID (Radio Frequency Identification). As the name suggests, RFID is a technology that uses radio frequencies to identify objects. Anyone who has ever listened to the radio has likely tuned in to a specific frequency to listen to their desired station. Although various radio stations transmit signals at different frequencies, the radio selects and receives only the desired frequency. RFID also exchanges information based on this principle.
To implement RFID technology, you need an RFID tag and a reader. A tag generally refers to a small identification device attached to a product, but in this context, it refers to devices such as transit cards or card-shaped devices that people carry. The transit card is the RFID tag, and the device installed at bus or subway turnstiles is the reader. A tag consists of an integrated circuit (IC) chip that stores information and an antenna. If you disassemble an actual transit card, you’ll see a chip about the size of a fingernail surrounded by thin metal wires; these wires act as the antenna. The antenna transmits electrical signals from the chip as radio waves or receives radio waves from external sources.
Generally, RFID tags such as transit cards do not continuously transmit radio waves on their own. When the reader emits a radio wave, the tag draws the necessary power from that wave to activate itself. This is called passive RFID. Once activated, the tag transmits its information to the reader via radio waves, and the reader decodes this to retrieve the necessary information. Simply put, communication occurs when the reader sends a signal first and the tag responds to it. Since this process takes place in a very short amount of time, users can complete a payment simply by lightly holding their card up to the terminal.
Why RFID Can Replace Barcodes
Thanks to these technical characteristics, RFID has long been recognized as a technology capable of complementing or replacing barcodes. Conventional barcodes work by shining light on a pattern of black and white stripes and analyzing the reflected light to read the information. Since black absorbs most of the light and white reflects it, the stored information can be read by analyzing the pattern of reflected light.
In contrast, because RFID uses radio waves, information can be read even if there are obstacles—such as paper, plastic, or a bag—between the tag and the reader, as long as the radio waves can pass through them. It also offers the advantages of being able to be read from relatively greater distances than barcodes and of reading multiple tags simultaneously. This difference arises because light cannot pass through objects, whereas radio waves can pass through certain non-metallic materials. For example, inside a sealed room, you cannot directly see the light from outside, but sounds from outside are transmitted to some extent through the walls. Of course, sound and radio waves are different types of waves, but this is a useful analogy for understanding their ability to pass through obstacles.
Furthermore, since RFID stores information on an integrated circuit chip, it can store far more data than conventional barcodes. An integrated circuit refers to a circuit in which numerous electronic circuits are integrated into a single semiconductor chip, rather than the traditional method of connecting individual components one by one onto a circuit board. Thanks to these technological advancements, circuits have become extremely small and thin, and today they have been miniaturized to the point where they can be easily embedded inside transit cards or credit cards.
Various Applications of RFID
Currently, RFID is widely used not only in transit cards but also in Hi-Pass, the electronic toll collection system for highways. Furthermore, in the logistics and distribution sectors, it is used for managing the receipt and shipment of goods as well as inventory control, and in hospitals, it is utilized for managing medical equipment and patients. In the livestock industry, RFID technology is applied to electronic ear tags for individual animal identification, and in sporting events such as marathons and triathlons, it is used to automatically measure athletes’ times. Beyond these, RFID technology is utilized in various other fields, including access control systems, employee ID cards, student ID cards, library book management, and electronic passports.
As such, RFID can store more information than traditional barcodes, can recognize multiple tags simultaneously, and is conducive to automation; consequently, its scope of application is steadily expanding across all industries.
Challenges RFID Must Address
However, despite these advantages, there are challenges that must be addressed in the use of RFID. The first is the issue of security and privacy protection. Since RFID can store large amounts of information, it is crucial to securely protect the stored data. Although encryption and authentication technologies are continuously advancing, it is impossible to completely rule out the possibility of unauthorized attempts to read or duplicate information in systems where appropriate security measures are not in place. Furthermore, given that RFID devices are distributed and operated across various locations, systematically managing the security of the entire system is also considered a key challenge.
The second challenge involves international standards and interoperability. Although international standards for RFID have been steadily established, differences in frequencies and specifications based on country and application still exist. These differences sometimes make it difficult to operate systems identically across countries, and standardization efforts to enhance international compatibility are ongoing.
How will RFID technology evolve in the future?
Currently, RFID has already established itself as a core technology in various industries, including public transportation cards, Hi-Pass, logistics, distribution, healthcare, and manufacturing. Its scope of application continues to expand as it integrates with the Internet of Things (IoT), artificial intelligence (AI), and cloud technology. In particular, it can efficiently manage more information than barcodes and offers excellent integration with automated systems, significantly contributing to increased productivity and convenience in industrial settings.
Of course, challenges such as security and international standardization remain. However, if these issues are continuously addressed, RFID technology will be utilized in an even wider range of fields and evolve into a core technology that makes our daily lives even more convenient.
