What is an RFID Tag? Types, Working, EPC & RFID-Based Billing System

Introduction

Radio Frequency Identification (RFID) is a technology used to identify and track objects using radio waves. An RFID system consists mainly of an RFID tag and an RFID reader. RFID tags can store identification and other object-related information and transmit this information to a reader without requiring direct line-of-sight.

What is an RFID Tag?

An RFID tag is a small electronic device that contains a microchip and an antenna. It can be attached to an object that needs to be identified or tracked using radio frequency technology.

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• The antenna of the RFID tag receives signals from the RFID reader and sends a response back to the reader.
• The response may contain information such as a unique serial number, stock number, or production date.
• Some RFID tags require a battery, while most passive tags operate without a battery.
• Passive RFID tags obtain the required energy from the electromagnetic field generated by the reader.
• The data stored in an RFID tag can be transmitted over several meters, depending on the type of tag and RFID system.
• RFID tags do not require a direct line-of-sight with the reader and can be attached to moving objects.

Types of RFID Systems

RFID systems can be classified into three configurations based on the type of reader and tag used.

1. Passive Reader Active Tag (PRAT)

A Passive Reader Active Tag (PRAT) system uses a passive reader that only receives signals from an active tag. Since the tag contains its own power source, the operating range of the system can extend to several feet or more, depending on the implementation.

2. Active Reader Passive Tag (ARPT)

An Active Reader Passive Tag (ARPT) system uses an active reader and a passive tag. The active reader transmits signals to the passive tag and receives the response from the tag.

3. Battery-Assisted Passive Tag (BAP)

A Battery-Assisted Passive (BAP) tag works similarly to a passive tag, but it contains a small battery. The battery assists the tag’s internal circuitry and enables it to respond more effectively when it receives a signal from the reader.

6 Types of RFID Tags

1. Passive RFID Tags

Passive RFID tags are generally less expensive because they do not contain an onboard battery. They obtain energy from the radio-frequency signal transmitted by the RFID reader. Therefore, the reader must be sufficiently close to the tag for communication to take place. Each passive tag can have a unique identification number that allows the RFID reader to distinguish one tag from another.

2. Active RFID Tags

Active RFID tags contain an onboard battery. They can periodically transmit identification signals to an RFID reader and generally provide a longer communication range than passive tags.

3. Battery-Assisted Passive (BAP) Tags

Battery-Assisted Passive tags contain a small battery that powers the tag’s internal circuitry. However, the tag communicates in response to a signal from the reader, combining characteristics of passive and active RFID technologies.

4. Read-Only Tags

Read-only RFID tags have a unique, factory-assigned identification number. This number is typically used as a key to retrieve additional information from a database.

5. Read/Write Tags

Read/write RFID tags allow users or systems to write object-specific information to the tag. The stored information can also be read when required.

6. Field-Programmable Tags

Field-programmable RFID tags can be programmed by the user. The information can generally be written once and then read multiple times. For example, a user can write an Electronic Product Code (EPC) to the tag.

Construction and Working of an RFID Tag

An RFID tag is an important component of an RFID system. It stores identification data that can be communicated to an RFID reader using radio-frequency signals. An RFID tag generally consists of the following components:

• Microchip: Stores and processes identification and other data.
• Antenna: Receives radio-frequency signals from the reader and transmits the tag’s response.
• Memory: Stores information such as identification numbers and other object-related data.
• Modulation and Demodulation Circuitry: Helps the tag communicate using radio-frequency signals.
• Power Circuitry: In passive tags, the required operating energy can be obtained from the signal transmitted by the RFID reader.

How Does an RFID Tag Work?

1. The RFID reader transmits an encoded radio-frequency signal.
2. The RFID tag receives the signal through its antenna.
3. In a passive tag, the received electromagnetic energy is used to power the tag’s internal circuitry.
4. The tag processes the received information.
5. The tag responds to the reader with its identification or other stored information.
6. The RFID reader receives the response and forwards the information to the connected system for further processing.

The information transmitted by the tag may include a unique serial number, stock number, production date, or other object-related information.

Electronic Product Code (EPC)

One type of information that can be stored in an RFID tag is the Electronic Product Code (EPC). An EPC can be used to uniquely identify products or objects in an RFID-based identification system. A commonly referenced EPC format contains 96 bits. The information is divided into different fields that identify the protocol, organization, object class, and unique serial number.

Thus, the EPC structure described above contains a total of 96 bits.

RFID-Based Billing System

One practical application of RFID technology is an RFID-based billing system. It can help reduce the time customers spend waiting in queues at shopping malls and supermarkets.

Need for an RFID-Based Billing System

In conventional billing systems, customers select products and take them to a billing counter. Each product is then scanned individually using its barcode. During busy periods, this process can result in long queues and increased waiting times. An RFID-based billing system can automate much of this process by identifying products through RFID tags.

Working of an RFID-Based Billing System

1. A shopping trolley equipped with an RFID reader and an LCD display is provided to the customer at the entrance.
2. Each product contains or has an RFID tag attached to it.
3. When a customer places a tagged product in the trolley, the RFID reader detects the tag.
4. The product information, such as name, quantity, and price, is displayed on the LCD.
5. The product information is simultaneously transmitted wirelessly to the central billing system.
6. The central system records the products selected by the customer and calculates the bill.
7. When the customer reaches the billing counter, most of the billing process has already been completed.
8. The staff can physically verify the products and collect the payment.

Advantages of RFID-Based Billing

• Reduces customer waiting time at billing counters.
• Helps automate product identification.
• Reduces the need to scan every product individually using a barcode scanner.
• Provides product information such as name, quantity, and price on the trolley display.
• Can reduce manual errors during billing.
• Improves the efficiency of the overall billing process.
• Can help identify products even when there is no direct line-of-sight between the tag and reader.

Applications of RFID Tags

RFID tags are used in a wide range of applications where automatic identification and tracking are required.

• Retail and supermarket inventory management
• RFID-based billing systems
• Supply chain and logistics management
• Warehouse management
• Asset tracking
• Access control and identification
• Product tracking
• Library management systems
• Transportation and toll collection systems

Conclusion

RFID tags are compact electronic devices that use radio-frequency communication to identify and track objects. Depending on their design, RFID tags can be passive, active, battery-assisted passive, read-only, read/write, or field-programmable. Unlike conventional barcode systems, RFID technology does not necessarily require direct line-of-sight between the reader and tag. This makes RFID useful for applications such as inventory management, asset tracking, logistics, retail, and automated billing systems. An RFID-based billing system can significantly improve the shopping experience by automating product identification and reducing the time required at billing counters.