1 Introduction
Automatic Identification (Auto-ID) systems have become commonplace in access
control and security applications, in industries requiring the tracking of products
through the supply chain or manufacturing process, and in industries requiring
the identification of products at the point of sale or point of service. Perhaps the
most widely recognized Auto-ID system is the bar code system developed during
the early 1970’s. More recently, Radio-Frequency Identification (RFID) systems
have begun to find greater use in automatic identification applications. RFID
systems consist of Radio Frequency (RF) tags, or transponders, and RF tag readers,
or transceivers. The transponders themselves typically consist of integrated
circuits connected to an antenna [8]. The use of silicon-based microchips enables
a wide range of functionality to be integrated into the transponder. Typical
functionality ranges from large read/write memories to integrated temperature
sensors to encryp! tion and access control functionality. The transceivers query
the transponders for information stored on them. This information can range
from static identification numbers to user written data to sensory data.
The potential applications for RFID systems are numerous. Consider, for
example, supply chain management applications and the use of EAN-UCC bar
codes. Today, over 5 billion bar codes are scanned daily world-wide [6]. Yet,
most bar codes are scanned only once during the lifetime of the item, namely at
the check out. RFID systems, if strategically deployed, are a single platform on
which a number of supply chain management applications can be simultaneously