RFID (Radio Frequency Identification) is a wireless communication technology used to capture data, which may be linked to different identification attributes (serial number, position, colour, date of purchase, etc.)

Historically, Radio-frequency identification (RFID) technology has been in existence since early 1970. Then, the first RFID tags were used to track large items, such as livestock and airline luggage. Now, smaller and more sophisticated versions of RFID are used to track consumer products, vehicles, pets and even Alzheimer’s patients worldwide.

RFID tags are passive devices that have no power supply of their own. Instead they capture and re-radiate some of the radio energy sent towards them by the tag reader, such as the Oyster card checkers which can be found on London transport. These send out carrier waves at specific frequencies that cause resonance in circuits within the passive tag. This resonance can activate internal circuitry that can reflect back a simple “I’m here” response suitable for store security devices or can modulate this response with a short code which can uniquely identify the tag.

RFID SYSTEM COMPONENTS

RFID integration to any process is usually achieved according to three facets: Context, Capture and Control. In the context facet, one must explore the evolution environment of the process subjected to RFID integration, by studying the environmental conditions under which RFID tags will be operating. Inventorying information to collect from the process, and identifying communication constraints/obstacles inflicted by the process environment (interference, reflection, and other communication obstacles) must be investigated.

The capture facet deals with the selection of RFID equipment (tags and readers) to ensure accurate data collection from the explored process and environment. At this stage, operation frequencies, RFID tags reading range, RFID antenna locations, power control, information privacy and security issues are among few factors to be adjusted, for efficient data capture, and reliable RFID interrogation zones design. The control facet deals mainly with RFID system real-time control (middleware link to other enterprise applications,

EPC database, graphical user interfaces), and business intelligence rules implementation (information processing, system response to RFID tag triggered events, control rules, algorithms). Usually an RFID middleware is developed based on the constraints dictated by the context, and capture facets.

A basic RFID system is generally made of the following components:

• RFID tags fixed to entities with unique electronic product code (EPC) per entity (wireless RFID network);


• Networked RFID readers, and real time databases;


• RFID antennas for information exchange between the tags wireless network and middleware/control platforms.

There are two types of RFID tags:

• Passive which is RFID tag is powered by the electromagnetic energy, radiated from RFID reader antennas, based on backscattering. A passive tag can’t transmit radio waves of its own, and its information storage capacity and computing capability are limited. It can be read only at short range (0.6 to 3 meters).


• Active that the tag is powered by an on-board long-life battery that provides sufficient energy to allow independent communication capability within greater range (approximately 90 meters).

To establish communication between RFID tags and readers, antennas are required. There are several types of antennas for active and passive RFID systems:

• Linear


• Circular


• Wide band


• Narrow band


• Single


• Dual polarized antennas

Antennas are usually selected according to their beam width (for narrower or wider coverage):

A circular antenna has more inductance than a linear one, thus, it induces scattered waves in several directions, ensuring a wider interrogation zone coverage. The below picture shows the architecture of RFID technology.



The right side describes RFID middleware functionalities (user access, control interface, interaction with enterprise database and servers), while the left side describes the ad-hoc wireless RFID network integrated to the physical process under supervision/control.

Some RFID middleware are application specific, however the tendency is to ensure technological flexibility (compatibility with different RFID equipment), application flexibility (quick setup of different applications), and access flexibility (multiusers, concurrent and remote access).