adio frequency identification (RFID) is an enabling technology. By itself, RFID doesn’t provide much value, but it does enable companies to develop applications that create value.
RFID describes systems that use radio waves to transmit an object’s identity. There are several methods of identifying objects using RFID, but the most common is to store an ID or serial number that identifies a specific product along with other information, on a tag, which is a small microchip attached to an antenna. The antenna enables the chip to transmit whatever identification information it contains to a reader. The reader converts the radio waves from the RFID tag into digital information that software systems can use for processing.
Typically, when a reader reads a tag, it passes three things to a host computer system: the tag ID, the reader’s own ID, and the time the tag was read. By knowing which readers are in which locations, companies can know where a product is, as well as what it is, and by tracking the tag data by time, they can know everywhere it’s been.
How RFID Technology Works
The reader sends out electromagnetic radio waves. The tag’s antenna is tuned to receive these waves. A passive RFID tag draws power from the electrical field created by the reader and uses it to power the microchip’s circuits. The chip then augments the waves to reflect the data it contains back to the reader, which converts them into digital data.
RFID System Components
A complete typical RFID System is composed of the following four components (see Figure 1).
- RFID tags or transponders
- RFID readers or transceivers
- RFID middleware
- RFID software applications
|Figure 1: Typical RFID System Components. To create a complete RFID system, you need tags, or transponders, a reader, some middleware to increase data accuracy and reduce noise, and software applications to manage the data.
Radio waves are transmitted and received by an antenna. The antenna is designed to radiate energy and collect radio energy. The antenna functions for both the transmitter and receiver. Thus, an antenna’s tasks are to:
- Convert electrical signals to radio waves.
- Collect or receive radio waves and convert into electrical signals.
Tags, also called transponders, are small devices about the size of a grain of rice, containing a microchip attached to an antenna, and placed on or near the objects to be identified. The tags can be programmed with specific items of information, such as an ID or serial number. When a reader transmits an appropriate radio signals the tag reflects energy to the reader, allowing the tag to identify itself and its data.
Tags are typically differentiated and named according to their operating frequency, memory modes, memory size, type, and packaging, however, there are three basic tags/transponders from which to choose:
- Have a battery, which is used to run the microchip’s circuitry and to broadcast a signal to a reader
- Usually operate at 455 MHz, 2.45 GHz, or 5.8 GHz, and typically have a read range of 60 feet to 300 feet
- Are usually used on large assets, such as cargo containers, rail cars, and large reusable containers
- Can be always on alert or can be “awakened” when needed
- Have no power source or transmitter
- Draw power from the reader
- Are cheaper than active tags
- Require no maintenance
- Operate at low frequency, high frequency, and ultra-high frequency
- Combine some traits of both active and passive tags
- Use a battery to run the chip’s circuitry, but communicate by drawing power from the reader, and often “sleep” until awakened by a specific reader signal.
To retrieve the data stored on an RFID tag, you need a reader. A typical reader is a device consisting of one or more antennas that emit and receive radio waves. The reader passes digital information converted from radio waves to a computer system.
RFID readers use a variety of methods to communicate with tags. The most common method for reading tags at close range is “inductive coupling,” in which the antenna of the reader interacts with the antenna of the tag to create a magnetic field. The tag collects energy from this field and uses that to send back radio waves to the reader.
RFID software typically performs a specific function such as keeping track of inventory in a warehouse or reordering inventory based on items removed from a shelf in a retail store. Based on data the application receives from the tags about the items (whether they be retail products, pallets, cartons, shipments or trucks), the application takes appropriate action.
Based on events within the enterprise, the software would also send information to the readers to write data on individual tags, such as the sale of an item, or an emptied pallet, or a code specifying that a shipment that has left a warehouse and is bound for a retail outlet.
RFID applications tend to be specific to a vertical industry, such as supply chain, retail, medical, warehousing, etc. A software engineer typically doesn’t?and shouldn’t?need to develop expertise in RFID technology. Thus, multiple organizations are actively working to develop a systems interface layer that will let programmers work primarily at the application layer, without having to deal with the RFID hardware. This systems layer is called the RFID middleware layer.
Middleware is the glue that binds hardware components from lower layers to higher application layers. While in principle it’s a horizontal technology, to make it industrially useful, it often has hooks to industry-specific verticals where needed.
In the specific context of RFID, the middleware layer performs additional functions such as:
- Making read/write more reliable
- Pulling and pushing data through a network of readers to the correct location (much like a router)
- Controlling and monitoring readers
- Allowing secure read/write operations
- Reducing RF interference
- Handling tag-based and reader-based events
- Notifying an application
- Accepting and forwarding interrupt commands from an application
- Alerting users about exceptions
Architecturally, the RFID middleware layer would typically be divided into sub-layers, with the lower layers focusing on functions relating to reading from and writing to the tag reliably, robustly, and securely.
The upper layers are linked to the applications and therefore would typically provide hooks for applications including functionality such as:
- Product shipment tables
- Product routing and planning tables
- Tag tables
- Reader tables
- Portal tables
- Enterprise IT systems such as billing, ERP, SCM, and CRM
- Handling tag code standards such as the Electronic Product Code
Such lower middleware layers create abstract classes for readers, tags, the RFID network, etc. When new technology such as a reader with new protocols is available, its characteristics can be incorporated into the middleware, thereby requiring minimal structural or even code-level changes to the software.
The upper middleware layers, in addition to having hooks for applications, may also include additional data functionality such as cross-referencing tag IDs with shipment IDs, or shipment IDs with location IDs, or tag time-stamps with expected time of arrival of a shipment. They can store/retrieve such information from the database, so RFID applications could typically refer to the database IDs instead of the tag IDs.
Having solid middleware in place means programmers can focus on developing the business logic for applications instead of having to understand different kinds of hardware. Within a given application, an enterprise might need to support readers and tags from different manufacturers, active as well as passive tags, tags operating at different frequencies/protocols, or tags with different read/write reliability and specifications. Middleware simplifies these problems. Eventually, middleware might be able to reduce the time it takes to integrate RFID hardware into existing applications.
Standards are critical for many RFID applications, such as payment systems, or tracking goods or reusable containers in open supply chains. A great deal of work has been going on over the past decade to develop standards for different RFID frequencies and applications.
The International Organization for Standardization (ISO) has developed RFID standards for automatic identification and item management. For example, ISO has created standards for tracking cattle with RFID. ISO 11784 defines how data is structured on the tag. ISO 11785 defines the air interface protocol. ISO has also created a standard for the air interface protocol for RFID tags used in payment systems and contactless smart cards (ISO 14443), and in vicinity cards (ISO 15693). It also has established standards for testing the conformance of RFID tags and readers to a standard (ISO 18047), and for testing the performance of RFID tags and readers (ISO 18046). Here are some of the ISO standards already available.
- ISO 15693?Smart Labels
- ISO 14443?Contactless payments
- ISO 11784?Livestock
- ISO 18000 – Air interface protocol. The ISO 18000 series covers the air interface protocol for systems likely to be used to track goods in the supply chain. They cover the major frequencies used in RFID systems around the world. The seven parts are:
- 18000?1: Generic parameters for air interfaces for globally accepted frequencies
- 18000?2: Air interface for 135 KHz
- 18000?3: Air interface for 13.56 MHz
- 18000?4: Air interface for 2.45 GHz
- 18000?5: Air interface for 5.8 GHz
- 18000?6: Air interface for 860 MHz to 930 MHz
- 18000?7: Air interface at 433.92 MHz
Using RFID to track goods in open supply chains is relatively new and fewer standards have been finalized. ISO has proposed standards for tracking 40-foot shipping containers, pallets, transport units, cases, and unique items, all of which are at various stages in the approval process.
The Auto-ID Center and EPC Standards
The Auto-ID Center, which developed Electronic Product Code (EPC) technologies, chose to create its own air interface protocol for tracking goods through the international supply chain.
The Auto-ID Center was set up in 1999 to develop the Electronic Product Code and related technologies that could be used to identify products and track them through the global supply chain. Its mission was to develop a low-cost RFID system; because the tags needed to be disposable (a manufacturer putting tags on products shipped to a retailer was never going to get those tags back to reuse them). The system had to operate in the ultra-high frequency band, because only UHF delivered the read range needed for supply chain applications, such as reading pallets coming through a dock door.
The Auto-ID Center developed its own protocol and licensed it to EPCglobal on the condition that it would be made available royalty-free to manufacturers and end users.
The center also was charged with developing a network architecture?a layer integrated with the Internet?that would enable anyone to look up information associated with a serial number stored on a tag. The network, too, needed to be based on open standards used on the Internet, so companies could share information easily and at low cost.
RFID Business Applications
Radio frequency identification can be used in many different ways to create value. RFID technology is currently being used in applications such as:
- Asset Tracking?Companies put RFID tags on assets that tend to be lost or stolen often, that are underutilized, or that are just hard to locate at the time they are needed.
- Manufacturing?Companies are using RFID to track parts and work in process, reduce defects, increase throughput, and manage the production of different versions of the same product.
- Supply Chain Management?RFID technology is used to increase throughput, reduce shipping errors, and cut labor costs.
- Retailing?Retailers are using RFID to improve supply chain efficiency, to help reduce theft, and to make sure inventory is up-to-date.
- Payment Systems?RFID is used today to pay for road tolls without stopping; to pay for meals at drive-through windows; to pay for bus, subway, and train rides; and to pay for small retail purchases using contactless cards.
- Security and Access Control?RFID has long been used as an electronic key to control who has access to office buildings or areas within office buildings. RFID is also being used to secure assets. Most late-model cars come with an RFID reader in the steering column.
There are many other innovative uses for RFID. One system even uses active tags in a bracelet to locate children at theme parks.
In essence, RFID gives computers the capability to track the location of items or people?in other words, RFID is the gateway to location-based computing. Like database technology, speech technology, and the Internet, RFID opens brand-new areas for application development.