RFID is becoming as
ubiquitous as printed bar codes. In fact, in many venues, optically scanned bar codes have been entirely replaced
with embedded RFID tags. Clothing, high value electronics, packaged software, and even books have been using RFID
(sometimes in the form of NFC - near field communications) for many years. Now, major retailers like Wal-Mart have
made a commitment to making RFID ubiquitous. In the not-too-distant future, if you want to have your product sold
by some of these retailers, you will be required to integrate RFID tags.
The magic price mark for RFID is a couple cents per tag. At that level, RFID can be added to every product and
not represent more than a percent or two of the total cost.
This table summaries the protocols used in RID
tags that operate in the 800/900 MHz band assigned for ISM (Industrial, Scientific & Medical) use.
None Reader broadcasts all or part of ID code. Reader can request kill passcode.
None Reader broadcasts UID/SUID. Production set block lock bits. No kill command.
None Reader broadcasts UID/SUID. Production set block lock bits. No kill command.
(1) No mention of data rates specific to European operation. Reverse link is always
40 kbps. (2) For Auto-ID class 0, the tag data response is always known a priori (i.e., nothing has to be
computed based on the current bit). (3) Probabilistic collision arbitration implies that tag selection speed
will depend on the tag population size. This is a disadvantage. (4) These standards are limited by
the probabilistic nature of their collision arbitration protocols. Most of them assume a tag population
of ~250 tags.
Source: RF Design, July 2005 , by Rob
Glidden and John Schroeter. Click
here for the full article.
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