A fair reader collision avoidance protocol for RFID dense reader environments

A radio frequency identification system can establish a communication between tags and readers through a wireless connection. Due to the optimized coverage of the environment, the readers are placed close to each other in this system and hence it is called dense reader environment. The very property of such an environment leads to increase in the probability of occurrence of reader-to-reader and reader-to-tag collisions which consequently come up with decrease in performance of the network. To solve this problem, many various protocols have been proposed of which centralized ones provide higher throughput. Our proposed method can reduce reader-to-reader collision through combining TDMA and FDMA mechanisms and benefiting from sift probability function and fairness. Furthermore, we found that distance comparison between two readers can reduce reader-to-tag collision as well. Our simulations indicate that the proposed method provides better throughput, average waiting time and fairness than existing ones. Our method also supports the mobility of the readers.