Cheng-Hao Quan

The Slotted-LBT: A RFID Reader Medium Access Scheme in Dense Reader Environments

RFID technology as a core technology for realizing ubiquitous environment is emerged. Although it was developed rapidly in the past few years, the read rate is still a concern in the RFID technology adoption. At the same time it is also a technical issue which must be resolved. In order to increase the read rate, a number of researches have focused on the air protocol method and the medium access method. In this paper, we propose a distributed Slotted-LBT method to increase the number of readers which can read tags simultaneously, to provide a stable channel access time, and to reduce the interference among readers by using a channel zone. From the results in this research, compared with the existing normal LBT method, the proposed Slotted-LBT method shows that the coefficient of variation for the channel access time is reduced from 96% to 38% and the effect of interference is reduced by 28.48%. Besides, since each channel can be controlled separately, we can use categorized channels according to demanding features of manifold applications.

Adaptive Channel Hopping Algorithm for Reader Anti-collision in RFID systems

In RFID field, it is easy to interfere between adjacent channels as the frequency band and channel bandwidth are narrow. Especially, in case of the dense reader mode where the number of readers is more than the number of channels, the readers easily collide with each other. In this paper, we propose an algorithm to avoid reader collision in dense reader environment. First, we introduce the operation of our algorithm. And next, we show the simulation results of the proposed algorithm. Simulation results show performance improvement of our algorithm compared to existing LBT algorithm.