RFID Tagging

RFID Tagging System Introduction: Many of the applications of the Bat System involve computing systems reacting to the proximity of one object with another or the proximity of an object with an area of space. The continuous stream of readings from Bats allow constant monitoring of these interactions, with the result that devices can automatically personalize themselves to the user standing in front of them, and users can trigger a personalized service simply by moving their Bat into a pre-defined area of space usually called RFID Tagging. However, might it be possible to develop a system that allowed users too trivially (though not automatically) personalize devices and services, but which had lower infrastructure requirements than the Bat system?

Proximity using RFID Tagging: Companies built a low-cost, low-infrastructure, proximity-based user interface device that uses Radio Frequency IDentification (RFID) technology. Small passive RFID Tagging, each with a unique 64-bit identifier, is attached to equipment and is placed behind posters. Users carry a keyfob-sized personal RFID reader, which also has a unique identifier. To personalize a device, or activate a service denoted by a poster, a user scans the RFID Tagging with their reader, by moving the reader to within a few centimetres of the tag and activating the unit by pressing a button.

This generates a pair of unique identifiers that describe what action should be performed by the system for which user. Each reader also has a bidirectional 868MHz radio module, which allows it to communicate with a (software) monitoring service via a set of LAN-connected base stations (a base station unit is shown in the photograph on the right). The reader unit transmits the (tag ID, reader ID) pairs via this radio interface to the monitoring service, which then looks up the appropriate action to be taken based on the RFID tag ID. It then performs that action over the network, personalizing it (if necessary) to the user, based on the reader ID. The monitoring service can send feedback to the reader (which has a buzzer and tricolour LED) via the base stations, to indicate the status of the action (e.g. success or failure).

RFID Tagging System features: Many types of RFID tags are suitable for use in the system. Tags cost around 50 cents in medium-scale volumes, are very robust, and come in a range of sizes. Companies use flat, circular plastic-encapsulated tags with radii of 1-1.5cm, and thicknesses of around 1.5mm.

The reader units measure 6cm x 2.8cm x 2cm, and have been designed to fit on a user's keyring. They have a six-month battery lifetime. The base station units connect directly to an Ethernet network. They register automatically with the monitoring service via DHCP, and use anti-collision protocols to ensure that base station coverage areas can safely overlap. Each base station has a range of around 10m in a typical building. Extending system coverage is as simple as plugging a new base station into the Ethernet LAN.

RFID Tagging Key Features:

RFID provides a number of significant and powerful advantages over bar codes, including:

• RFID can store information dynamically
• Unlike barcodes, RFID systems not only allow the user to read information stored in a tag, but also to change or add information. However, the two technologies can be combined within a single reader i.e. to provide the capability of reading a bar code and writing back to a tag.
• RFID can be read from, and written to, through a variety of materials
• RFID tags can be read from, and written to, through a variety of non-metallic materials, including dirt, wood, steam, plastic, paint, water and even people!
• RFID does not require contact or line-of-sight for operation
• Tags can be read at distances of up to 1 meter, and unlike barcodes, do not require line-of-sight for effective operation.
• RFID tags have greater flexibility in their placement
• The fact that RFID tags do not require line-of-sight (coupled with their ability to be read through different materials) provides for greater flexibility in their placement. A wide variety of package styles even allows tags to be embedded within an object!
• RFID tags can be used in harsher environments
• Many tags operate effectively at extreme levels of temperature and humidity.
• RFID is extremely accurate
• RFID has the lowest error rate of all automatic identification technologies, with accuracy levels approaching 100%.
• RFID tags are secure
• The integrity of information stored in a tag may be protected using a range of comprehensive security options, specified by the user.
• RFID tags can carry large amounts of data
• The storage capacity of read/write RFID tags can range from around eight characters of user defined data to more than 250 characters.
• RFID tags can be used repeatedly
• As data stored in a read/write tag can be over-written, it can be used repeatedly.
• Multiple RFID tags can be read simultaneously
• Some RFID tags support the reading of multiple tags simultaneously. In contrast barcodes must be read individually.