RFID Anti-collision Protocol Based On Multi-bit Identification

RFID is an automatic identification technology where the reader identifies tags through a shared wireless channel. When multiple tags transmit at the same time, anti-collision protocol should be used to deal with the collision problem so as to ensure correct and efficient tag identification. Mainstream anti-collision protocols can be roughly divided into two classes-Aloha-based protocols such as Pure Aloha (PA), Slotted Aloha (SA) and Frame Slotted Aloha (FSA), and tree-based protocols like Tree Splitting (TS), Binary Search (BS), Query Tree (QT) and etc.When multiple collided bits exist in the receiving sequence, it’s impossible for the reader that applies a traditional anti-collision protocol to identify the corresponding transmission IDs, and the tags should retransmit according to certain rules. Such a mechanism will reduce the system efficiency and increase the energy consumption of tags. In order to increase the identification efficiency by making full use of collisions, this paper first presents a novel tag identification mechanism named the Collision Inversion (CI) method, which can identify the transmission tag IDs by their collided bits, so that multiple tags can be identified simultaneously in a single slot. Based on the CI method, anti-collision protocols named the Pure Collision Inversion (PCI) Protocol and the Multi-bit Identification (MBI) Protocol are proposed. Theoretical analysis shows that the identification efficiency of PCI is decided by the ID length, and it’s only suitable for limited circumstance. In order to overcome the drawback of PCI, MBI combines the identification mechanism of traditional tree-based protocol with PCI, thus can be both flexible and efficient. Simulation results show that compared to the mainstream protocols like the Query Tree (QT) Protocol, the Jumping and Dynamic Searching (JDS) Protocol and the New Enhanced Anti-Collision Algorithm (NEAA), MBI not only can increase the identification efficiency, but also can reduce the average energy consumption.