Abstract—Radio Frequency IDentification (RFID) has enabled
a wide range of automated tracking and monitoring applications.
However, RFID tags share a wireless communication medium
to deliver their information to the RFID reader which results
in tag collisions and, hence, a significant energy consumption
and delay in the interrogation process. Handling tag collisions
is a challenging task because of the limited capabilities available
to passive RFID tags. In classical anti-collision schemes, the
RFID reader interrogates all tags in its range at once using its
maximum transmission range, which results in many collisions
and wastes energy. In a previous work, we proposed a novel
approach in which the interrogation zone of an RFID reader
is divided into a number of ring-shaped clusters, and tags
of different clusters are read separately. We also proposed a
method that finds the optimal clustering scheme assuming an
ideal setting in which the transmission range of the RFID reader
can be tuned with high precision. In this paper, we consider
a more practical scenario in which the RFID reader has a
finite set of discrete transmission ranges rather than continuous
ones. This suits currently existing commercial RFID readers
that come with configurable output power. We present a delay
mathematical analysis for this optimization problem and devise
an algorithm that finds the optimal clustering efficiently. The
proposed approach can be integrated with any existing anticollision
scheme to improve its performance and, hence, meet
the demand of large scale RFID applications. Simulation results
show that our approach is able to make significant improvements
in saving energy and time by reducing collisions.