RFID Radio Frequency IDentification By: Jeremy Yager
RFID - Overview RFID, as the name suggests, uses RF devices to communicate identification information. This is achieved by using sma devices known as tags to carry unique identification for the object, person, or anima carrying the tag. In most appications, a second device, known as a reader, pos the RFID tag for its identification information.
History of RFID IFF: Identification, Friend or Foe. Deveoped in WWII by British to distinguish returning Aied aircraft from invading German bombers. In 60's and 70's RFID gained usage in inventory and access contro of radioactive/nucear materias.
Private Sector and Research In 1977, RFID technoogy was transferred to the private sector. The first appications were catte identification and monitoring--to repace branding--and in rairoad car inventory management. RFID aso began to see use in widife monitoring and research. RFID tags can be used to monitor anima movement without adversey affecting the anima, giving researchers more data to understand behaviors that may be difficut to observe directy.
Uses of RFID Today Inventory tags: Sma size and ow cost of tags aows widespread usage in inventory contro. For exampe, Wamart now requires top 100 suppiers to incude RFID tags on a merchandise. Shipping containers: In addition to inventory, tags can be used to monitor history, condition and security of container.
Uses in Manufacturing Manufacturing: RFID tags are used to track materia and processes on shop foors. In a newer appication, tags embedded in the foor give ocation information to mobie equipment (i.e. forkifts) to navigate autonomousy around the shop. These uses in industry center around the management buzzword Suppy Chain Visibiity
Other Uses of RFID No-stop to booths to improve traffic fow Cashess payment Security/Access Contro Supermarkets Medica monitoring Theft deterrent, e.g car-key RFID tags Any appication requiring unique identification of objects in an inexpensive and unobtrusive way
Types of RFID Tags There are three types of RFID Tags: Active Tags Passive Tags Semi-Passive Tags (actuay, technicay a subset of passive)
Active RFID Tags Active RFID Tags use a radio transceiver to communicate with tracking system. This requires the incusion of a battery with the unit. Pros: Longer range than passive. Battery aows much more sophisticated contro ogic. Cons: Larger and heavier due to battery. Currenty more expensive than passive tags.
Passive RFID Tags Passive tags use backscatter moduation of reader fied to communicate with reader. Purey passive tags use the reader s fied to power onboard ogic through power scavenging techniques. Pros: Very sma. Can be miimetric in dimension. Does not require a battery. Can be very inexpensive (<$0.25 each in arge quantities) Cons: Antenna system used for power scavenging and communication is difficut to design and to attach to the device. Readabe range is very imited. Onboard ogic capabiity is very imited.
Backscatter Moduation?! Antenna theory: A tuned receiving antenna retransmits a portion of incident RF energy. This retransmission is known as scattering-- backscattering if it is in the direction of the origina transmitter. This backscattering can be detected by another antenna. By continuousy tuning and detuning an antenna eement, the amount of backscattering can be controed.
Backscatter Moduation, Continued By changing the antenna eement tuning in a wedefined manner, backscattering from antenna can be moduated to transmit information. The signa is actuay the ampitude of the backscattering from the tag antenna. This method is used by a passive tags. Care must be taken with design, however. When antenna is detuned, the tag is no onger receiving power from the reader s fied. If the antenna spends too much time in the detuned state, the tag wi exhaust its energy storage and ose power without a battery backup.
Semi-Passive RFID Tags Semi-passive tags use battery power for ogic ike an active tag, and backscatter moduation for communication ike a passive tag. Pros: Antenna design can be optimized for communication, as in active tags, rather than compromise design for both power scavenging and communication. Can have more sophisticated onboard ogic. No radio transceiver required, as in passive. Cons: Readabe range is sti quite imited. Size and weight of battery.
Communication Protoco Design Decision: Who starts communication, the reader or the tag? Be carefu, this has known to degenerate into somewhat of a reigious war! Tag Taks First: Tag communicates as soon as it detects reader fied. Simpifies tag ogic, but ess secure because tag doesn't care what it is communicating with, as ong as sufficient fied strength is avaiabe. Reader Taks First: Tag waits for interrogation by reader before transmitting information. Opposite pros and cons versus Tag Taks First.
Frequency Bands of RFID LF band: 125 and 135 khz HF band 13.56 MHz These frequency bands can be used freey wordwide. The ow frequencies here optimize transmission distance by minimizing free-space osses. UHF band: 915 MHz MW band: 2.4 GHz These frequency specifications are for the US ony, Europe and Japan have different frequency specifications for UHF/MW.
Issues in RFID Tag Security: On-tag encryption can defend against eavesdropping, but this increases size and power requirement of tag ogic. Iega/unethica monitoring of RFID tags: This is a major controversy surrounding RFID right now. Embedding of RFID tags in humans: This has been proven to work, but shoud it be done?
Tag Security/Tag Lifetime Tags can remain functiona ong after origina intent (inventory) is no onger needed-- especiay passive tags that can essentiay work forever. Tags often use Tag-Taks-First mode, aowing anyone with the correct tag frequency and a high-gain antenna to eavesdrop on unsuspecting tag carriers.
Ethica Issues in RFID Tagging Passive RFID tags coud conceivaby used for surveiance of unsuspecting tag carriers More than ten states have passed egisation imiting and/or requiring conspicuous notice of the use of an RFID tag. "How woud you ike it if, for instance, one day you reaized your underwear was reporting on your whereabouts? Caifornia State Senator Debra Bowen, at a 2003 hearing "Spychips" -- Katherine Abrecht, founder of CASPIAN, a consumer privacy group
RFID Tags in Humans Successfu embedding of passive RFID tags in/under the skin has taken pace. Appications incude high-eve security, and ocation monitoring of menta patients. Skin-embedded RFID can ead to utimate in privacy intrusion. (Big Brother, reaized?!) As RFID becomes more popuar, this issue must be addressed.
Concusion RFID, ike any technoogy, has a variety of different uses for which it is we suited. RFID tags wi ony become cheaper and more powerfu with improving technoogy and design experience However, the potentia for abuse of this technoogy is vast and requires carefu consideration to avoid.
Questions?
Credits Picture credits: http://www.b17sam.com/ http://www.gobasecurity.org/ Wikipedia Larry Martin, The $1 Wireess Interface, Circuit Cear, Issue 163, February 2004