  Fast and efficient identify a large number of RFID tags in the region of
interest is a critical issue in various RFID applications. In this paper, a
novel sub-frame-based algorithm with a time-efficient frame size adjustment
strategy to reduce the time complexity for EPCglobal C1 Gen2 UHF RFID standard
is proposed. By observing the slot statistics in a sub-frame, the tag quantity
is estimated by the reader, which afterwards efficiently calculates an optimal
frame size to fit the unread tags. Only when the expected time efficiency in
the oncoming frame is higher than that in the previous frame, the reader starts
the new identification round with the updated frame. Moreover, the estimation
of the proposed algorithm is implemented by the look-up tables, which allows
dramatically reduction in the computational complexity. Simulation results show
noticeable throughput, time efficiency, and identification speed improvements
of the proposed solution over the existing approaches.
