The precedence of RFID is that it does not require direct contact or line-of-sight scanning. An RFID system consists of three components: an antenna and transceiver (often combined into one reader) and a transponder (the tag). The antenna uses radio frequency waves to transmit a signal that activates the transponder. When activated, the tag transmits data back to the antenna. The data is used to notify a programmable logic controller that an action should occur. The action could be as simple as raising an access gate or as complicated as interfacing with a database to carry out a monetary transaction. Low-frequency RFID systems (30 KHz to 500 KHz) have short transmission ranges (generally less than six feet). High-frequency RFID systems (850 MHz to 950 MHz and 2.4 GHz to 2.5 GHz) offer longer transmission ranges (more than 90 feet). In general, the higher the frequency, the more expensive the system. RFID is sometimes called dedicated short range communication (DSRC).
28.2 RFID Primer
With all the potential doomsday scenarios that critics like to associate with the use of RFID systems, why would anybody even consider doing this? This is because RFID systems offer three distinct advantages over traditional identification systems:
1. Automation. While optical bar codes require a line of sight for readout, i.e., either careful orientation of tagged goods with respect to the reader, or manual intervention, RFID tags promise unsupervised readouts. This increases the level of automation possible, as tagged items do not need precise orientation during the readout process.
2. Identification. RFID tags also offer a much higher information density than bar codes, allowing manufacturers and vendors not only to store a generic product identifier on an item, but an individual serial number, which in turn can point to a database entry with detailed item information .
3. Integration. The wireless coupling between reader and tag also allows manufacturers to integrate tags unobtrusively into products, thus freeing product design as well as making identifiers more robust (e.g., protection from dirt, but also against removal).
The primary use of an RFID tag is for the purpose of automated identification or AutoID for short. This is exactly what its predecessor – the bar code – was created for. RFID technology is now being hailed as the next step in checkout-automation, completely eliminating checkout lines as shoppers can simply walk through a supermarket gate and have all their items automatically billed to their credit card within seconds. However, another set of applications additionally requires not only identification, but also authentication. The idea of token-based authentication is that both items and users can be reliably identified, based on an unforgeable token that they carry. Users can thus prove their entitlement to a specific service (e.g., to enter a building) while items can prove their authenticity (e.g., an expensive watch, organic food,...