21-08-2012, 02:28 PM
Battery-Powered RFID
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ABSTRACT
In this article, we compare the different types of batterypowered
RFID tags that are available today and explore
several emerging wireless standards that are candidates for
active RFID tagging. We also present an active RFID
platform we have developed and a supply chain application
implemented on that platform.
INTRODUCTION
Passive (battery-less) RFID technology has been the
primary candidate for tagging of cases and items, where the
tags are not reused and the cost of tags is critical. However,
in situations where the performance of the RFID tag is
critical or a long read range is required, battery-powered
RFID tags are preferred. Examples include tagging
shipping containers, freight packages, valuable assets, or
applications requiring sensors, such as cold-chain shipping,
and asset tracking [8]. RFID tags with an onboard power
source are also necessary for data-logging applications in
which tags must operate independently of the reader.
Advantages of Semi-Passive RFID over Active RFID
• EPC compatibility – The primary advantage of a semipassive
RFID tag over active RFID is that it can be used
with existing passive RFID infrastructure. Since both
passive RFID and semi-passive RFID use a backscatter
mechanism to communicate with the reader, a passive
RFID reader does not need to distinguish between these
two types of tags. There exist long-term plans for EPC
Global to develop an EPC standard for active tags as well
(Class 4 or Class 5); however, this will probably not
happen for some time.
• Lower Tag Cost – Since a semi-passive RFID tag does
not require a radio transmitter circuit, the cost of the
electronic tag chip can be less than that of an active RFID
tag. However, single chip solutions are now available for
both, and the difference in cost is small relative to the
cost of the battery, for example. It should also be noted
that the active RFID chips are also being used in other
industries such as sensor networks and manufactured by
many vendors; thus in the near future, due to the
economies of scale, the cost of an active RFID chip may
actually be less that the cost of a semi-passive RFID chip.
PALLET TRACKING APPLICATION
To explore real-life usage scenarios of this active RFID
platform, we developed a Pallet Locating and Tracking
System (PLTS) and deployed it to analyze one segment
(Printer-Wholesaler) of a magazine supply chain3 illustrated
in Figure 3. The supply chain flows as follows – first, the
Publisher sends electronic files to the Printer for printing
hardcopies. Next, the Printer sends the printed magazines to
several Wholesalers around the country. Finally, the
Wholesalers redistribute the magazine copies to local
newsstands.
CONCLUSIONS
As demonstrated in the magazine supply chain application,
IEEE 802.15.4 based RFID platform could be efficient,
economical and reliable. We also find that this platform
could be used for a wide variety of applications. For
example, we are currently exploring the possibilities of
designing a prisoner tracking and a construction supply
chain management using our IEEE 802.15.4 based active
RFID platform.