It also includes the spectrum management of RFID operation.
Frequency hopping or frequency agile systems are the suggested techniques. An allocated
frequency band, as allowed by local regulatory body, is divided into sub-bands or channels.
A reader will only use a certain channel for communication, not the entire allocated
frequency band.
EPC C1G2 covers single, multiple, and dense reader modes; multiple reader mode is for
an environment where the number of simultaneously active readers is modest relative to
the number of available channels while dense reader mode is for an environment where the
number of simultaneously active readers is comparable with more than the number of
available channels.
This document only focuses on dense reader mode. In dense reader mode, for narrow
bandwidth (European 200 kHz) channels, it is suggested in this protocol that odd-numbered
channels should be used for tag backscatter while even-numbered channels will be used
for reader interrogation. For a wide bandwidth channel (USA FCC 500 kHz channel
(FCC, 2001)), all available channels can be used for reader interrogation as tag backscatter
replies will be located at the boundaries of these channels.
7.2.4 Challenges in Dense Reader Environment in Europe
With the implementation of ETSI 302 208 and EPC C1G2, it is clear that when a reader is
operating at a certain sub-band or channel, this reader will effectively prevent other readers
from using that channel within an unacceptably large area.
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