Active RFID tags, on the other hand, have an internal power source, and may have longer range and larger memories than passive tags, as well as the ability to store additional information sent by the transceiver. At present, the smallest active tags are about the size of a coin. Many active tags have practical ranges of tens of metres, and a battery life of up to 10 years.
The RFID system
An RFID system may consist of several components: tags, tag readers, edge servers, middleware, and application software.
The purpose of an RFID system is to enable data to be transmitted by a mobile device, called a tag, which is read by an RFID reader and processed according to the needs of a particular application. The data transmitted by the tag may provide identification or location information, or specifics about the product tagged, such as price, color, date of purchase, etc. The use of RFID in tracking and access applications first appeared during the 1980s. RFID quickly gained attention because of its ability to track moving objects. As the technology is refined, more pervasive and possibly invasive uses for RFID tags are in the works.
In a typical RFID system, individual objects are equipped with a small, inexpensive tag. The tag contains a transponder with a digital memory chip that is given a unique electronic product code. The interrogator, an antenna packaged with a transceiver and decoder, emits a signal activating the RFID tag so it can read and write data to it. When an RFID tag passes through the electromagnetic zone, it detects the reader's activation signal. The reader decodes the data encoded in the tag's integrated circuit (silicon chip) and the data is passed to the host computer for processing.
Patient identification
In July 2004, the Food and Drug Administration issued a ruling that essentially begins a final review process that will determine whether hospitals can use RFID systems to identify patients and/or permit relevant hospital staff to access medical records. The use of RFID to prevent mixups between sperm and ova in IVF clinics is also being considered.
Also, the FDA recently approved the country's first RFID chips that can be implanted in humans. The 134.2 kHz RFID chips, from VeriChip Corp., a subsidiary of Applied Digital Solutions Inc., can incorporate personal medical information and could save lives and limit injuries from errors in medical treatments, according to the company. The FDA approval was disclosed during a conference call with investors.
Some in-home uses, such as allowing a refrigerator to track the expiration dates of the food it contains, have also been proposed, but few have moved beyond the prototype stage.
Human implants
Implantable RFID chips designed for animal tagging are now being used in humans as well. An early experiment with RFID implants was conducted by British professor of cybernetics Kevin Warwick, who implanted a chip in his arm in 1998. Applied Digital Solutions proposes their chip's "unique under-the-skin format" as a solution to identity fraud, secure building access, computer access, storage of medical records, anti-kidnapping initiatives and a variety of law-enforcement applications. Combined with sensors to monitor body functions, the Digital Angel device could provide monitoring for patients. The Baja Beach Club in Barcelona, Spain uses an implantable Verichip to identify their VIP customers, who in turn use it to pay for drinks. The Mexico City police department has implanted approximately 170 of their police officers with the Verichip, to allow access to police databases and possibly track them in case of kidnapping.
Passports
A number of countries have proposed to implant RFID devices in new passports, to facilitate efficient machine reading of biometric data. Security expert Bruce Schneier said of these proposals: "It's a clear threat to both privacy and personal safety. Quite simply, it's a bad idea." The RFID-enabled passport uniquely identifies its holder, and in the proposal currently under consideration, will also include a variety of other personal information. This could greatly simplify some of the abuses of RFID technology, and expand them to include abuses based on machine reading of data such as a person's nationality. For example, a mugger operating near an airport could target victims who have arrived from wealthy countries, or a terrorist could design a bomb which functioned when approached by persons from a particular country.
The US State Department initially rejected these concerns on the grounds that they believed the chips could only be read from a distance of 10 cm (4 in), but in the face of 2,400 critical comments from security professionals, and a clear demonstration that special equipment can read the test passports from 30 feet (10 m) away, as of May 2005 the proposal is being reviewed.
WiMAX
WiMAX is a wireless metropolitan area network (MAN) technology that can connect IEEE 802.11(Wi-Fi) hotspots to the Internet and provide a wireless extension to cable and DSL for last mile (last km) broadband access. IEEE 802.16 provides up to 50 km (31 miles) of linear service area range and allows users connectivity without a direct line of sight to a base station. Note that this should not be taken to mean that users 50 km (31 miles) away without line of sight will have connectivity. The technology also provides shared data rates up to 70 Mbit/s, which, according to WiMAX proponents, is enough bandwidth to simultaneously support more than 60 businesses with T1-type connectivity and well over a thousand homes at 1Mbit/s DSL-level connectivity.
It is also anticipated that WiMax will allow interpenetration for broadband service provision of VoIP, video and internet access- simultaneously. Most cable and traditional telephone companies are closely examining or actively trialing the potential of WiMax for "last mile" connectivity. This should result in better pricepoints for both home and business customers as competition results from the elimination of the "captive" customer bases both telephone and cable networks traditionally enjoyed. Even in areas without preexisting physical cable or telephone networks, WiMax could allow competitors joint access to any subscriber within range; home units the size of a paperback book that provide both phone and network connection points are already available- and advertised as "plug and play" easy to install. There is also interesting potential for interoperability of WiMax with cellular networks. WiMax antennas can "share" a cell tower without compromising the function of cellular arrays already in place. Companies that already lease cell sites in widespread service areas have a unique opportunity to diversify- and often already have the necessary spectrum available to them (i.e. they own the licenses for radio frequencies important to the speed and/or range of the WiMax connection). WiMax antennae would be connected to a service provider's "head end" via either a light fiber optics cable or a directional microwave link. Some cellular companies are evaluating WiMax as a means of increasing bandwidth for a variety of data-intensive applications.
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