A hierarchical structure based reader anti-collision protocol for dense RFID reader networks

Recently, RFID systems have been widely applied in many applications. And as many RFID readers are being deployed increasingly, an incorrect operation due to reader collisions deteriorates the quality of systems. Especially, as the number of channels relatively to the number of readers becomes scarce, the dense reader environment needs to be newly considered. In this paper, we present a hierarchical structure based reader anti-collision protocol for dense RFID reader networks. In this protocol, a reader should transmit pre-pulse and post-pulse to adjacent readers and make readers' hierarchy. By using the hierarchical structure, many readers efficiently can share the same channel for spectrum efficiency when the number of channels is insufficient. Moreover, the time coordination scheme among the adjacent readers and the frequency division scheme among the reader groups are used in order to avoid reader collisions. Consequently, reader collisions can be mitigated and the rate of channel occupancy is enhanced. Simulation results show that our proposed protocol has significantly better performance than the existing protocols.