The next antenna on its immediate right is using channel 8, which is six channels away.
Channel 10, though is the furthest channel away, is not chosen. This is because the
arrangement of {2, 8, 4, 10, 6} gives best channel separation between every channel.
7.6 Synchronized RFID System Fine-Tuning
Fine-tuning of a synchronized RFID system, as presented in this section, can be carried out
to further reduce the tendency of reader collision. The ?¬?ne-tuning methods discussed later
include the reduction of output power, the reduction of overall reader talking time, the use
of external sensors, the use of RF opaque or absorbing materials, and the frequent
rearrangement of channel allocations.
7.6.1 Reduction of Output Power
Although up to 2 W ERP can be used in single or small population reader environment, in
dense reader populations this higher power may not be necessary. Currently, a state-ofthe-
art reader can read up to 10 m. However, normal reading operations do not require
such a read range. In the case study presented in Section 7.5, the dock doors of the
warehouse are around 3 m in width. Since two antennas are positioned facing each other
in every dock door, the read range required is also around 1.5??“2 m. By reducing the
radiated power of readers, the minimum distance between two antennas using the same
channel can also be reduced, which is bene?¬?cial in a dense reader environment.
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