10.7 Radio Frequency Identification (RFID) Tags
A radio frequency identification (RFID) tag is an object that can be incorporated in or
attached to another object for the purpose of identification using radio waves. It can be
used on living things, e.g. pets, as well as inanimate objects. Each RFID tag has two
main elements:
� An integrated circuit that modulates/demodulates a radio signal, stores and processes information.
� An antenna for transmitting and receiving information. There are three kinds of RFID tag - passive tags, active tags and semi-passive tags.
10.7.1 Passive RFID Tags
The power for passive RFID tags is provided by the small electrical current induced in
the antenna by the incoming radio frequency signal. These tags transmit an ID number
in response to the incoming signal, though it is possible to provide more data, and
have a range from around 10 cm to a few metres. The actual range is dependent upon
both the antenna design and the radio frequency utilised.
The lack of a power supply means that these devices are small and can even be
incorporated as part of a printing process, for example RFID chips have been
manufactured that are 0.05 mm x 0.05 mm and embedded in sheets of paper. Low
frequency tags can be embedded under the skin of animals and humans.
10.7.2 Active RFID Tags
Active tags have their own internal power source and are, therefore, larger than
passive tags and have a greater range. The power supply powers the integrated circuit
and also broadcasts the signal to the reader. This allows for the tags to conduct
‘sessions’ with the reader, making them more reliable than passive tags. The higher
power also allows them to be more effective in difficult environments such as metal
containers, e.g. vehicles, and underwater.
Many active tags have a battery life of up to 10 years, ranges of hundreds of metres
and can store much more data than passive tags. There are applications that utilise
such tags to monitor temperature, radiation levels, light intensity, etc. by the addition
of sensors.
10.7.3 Semi-passive RFID Tags
Semi-passive tags are similar to active tags in that they have their own power supply
but this is only used to power the microchip and not to broadcast a signal. The
broadcast process is the same as for passive tags.
10.7.4 Uses of RFID Tags
RFID tags are now being incorporated into the passports issued by a number of
countries including the United States, United Kingdom and Malaysia. It is possible to
use such technology to store the information held in the passport, a history of travel
and a digital picture of the passport owner.
In a large number of countries this technology is incorporated into travel cards for use
on public transport. These systems are either pre-payment schemes, where the user has
paid in advance for a certain amount of travel, or pay-as-you-go schemes, where
payment is charged to a credit or debit card supplied by the user.
There are a number of automotive applications utilising the technology. Car keys may
incorporate RFID tags so that the car will not start without the correct ID. They are
also used in truck and trailer tracking within shipping yards.
Many libraries have incorporated RFID tags into their stock to replace barcodes. This
should reduce the amount of staff time required to process loans and also the risk of
repetitive strain injury from the repeated reading of codes. Other applications include
the timing of competitors in sporting events, general stockholding data and the
identification of prison inmates.
10.7.5 Concerns Regarding the Use of RFID Tags
One of the major concerns is the security of data. Readable tags give rise to concerns
regarding access to the location of individuals and also the security of corporate data.
A number of organisations have expressed concern at the embedding of RFID in
consumer goods, in many cases without the knowledge of the customer. When a
purchase is made with a credit card it is perfectly possible to link the purchaser to the
item and if the tag remains active this creates a greater privacy concern.
Encryption is used to prevent access to sensitive data but the encryption of UK
passport chips was broken in less than 48 hours and the inability to detect that the data
has been read increases the vulnerability of the passport system. In 2006 it was
reported that an RFID buffer overflow bug could infect airport terminal baggage and
passenger databases allowing theft of data held about a passenger.
There are a number of techniques incorporated in RFID systems to improve privacy.
The most obvious one is the physical disabling of the chip. Many RFID tags also have
an inbuilt ‘kill’ function, whereby on receipt of the correct code the chip renders itself
useless. Technologies are also emerging that give the tag owner control over privacyenhancing
technology that is built into the system.
10.7.6 The Future of RFID Tags
The use of RFID tags is expanding and includes the embedding of such tags under
human skin, despite some ethical and religious objections. The cost of tags has, to
date, prevented their incorporation into every item purchased commercially from a
store but their use in this context is increasing. As we move closer to the notion of
ambient computing, where we and our possessions automatically interact with
surrounding wireless networks, it is likely that the use of RFID tags will spread.
Source:
© NCC Education (National Center for Computing www.nccedu.com )
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