RFID System Architecture

The following criteria must be fully considered and answered in order to design a successful RFID system.

• Amount of Data Stored in Tag - (tag cost increases as storage increases)

Minimal - Unique id only.  This will require accessing an information system each time a tag is read to match the tag id with the data record for that tag.

Some information storage - Tag could contain enough information for some decisions to be made without accessing an information system. Data could be batched and unlinked to the information system on an as needed basis.  Other decisions may require a real time link to the information database record for that tag.

Full data storage in tag - Tag could contain all the information necessary for decisions to be made at the read point without accessing an information database.  Data collected could be batched and linked to an information system on an as needed basis.

• Read/Write Capability - (tag and reader costs increase as capability is added)

Read only tag - Data is encoded into the tag at the time of manufacture.  No changes in the tad data can be made at a later date.

Write once, read many tag - Data can be written into the tag when it is first used by a separate device.  No changes in the tad data can be made at a later date.

Read and Write - Data can be read from the tag and new or additional data can be written to the tag at some or all read locations.

• Read and/or Write Distance - This requirement is application dependent. Write distance is typically less than read distance.  (costs increase as distance increases)

Minimum read distance - Typical is 2 to 5 inches.  This may be desirable in some applications to prevent reading of other tags further away which could provide false information at the desired read point.  Example: Secured area access.  Read only the tag of the person directly in front of the access point.

Average Read Distance - Typical is 2 to 10 feet.  This may be a requirement for moving items or reading multiple items at the same time.

Maximum Read Distance - Typical is 20 to 1000 feet.  This may be a requirement for large items or reading many different items within the area.

• Frequency of Operation - This should be carefully considered in order to minimize potential frequency conflicts with other RF systems in the area.  Some frequencies used in the US cannot be used in other countries. (costs increase with the higher frequency tags)

Low frequency Tags - Typical is 66 to 125 Khz.  This frequency range usually requires large antenna systems to increase range.  Loop antennas are used extensively.  Most frequencies in this range can be used world wide.

Medium Frequency Tags - Tags operate on frequencies between 433 MHz to 928 MHz.  The 902 to 928 MHz frequencies cannot be used in most countries outside the US.

High Frequency Tags - Tags operate on frequencies between 2.4 to 5.6 GHz.  These frequencies may be used in many countries outside the US Read and write ranges are typically less then lower frequency tags. More radio spectrum is available in these bands.

Created by Randall Jackson	Other Sites by the Webmaster		Top	Page updated: July 25, 2005