Research Of Anti-collision Algorithm Based On Radio Frequency Identification (RFID) System

Radio frequency identification (RFID) technology is a non-contact and automatic identification technology based on the principle of radio frequency. With the characteristics of fast identification speed, strong real-time and far identifiable distance, RFID has been widely applied to the logistics, warehouse management, retail, positioning and other fields.In practical application, the situation that more than one reader and tag exist in the RFID system at the same time is often encountered. When the system is working, due to the mutual interference generated by the wireless communications, tag collision and reader collision will occur. In this case, system identification will fail. Methods to solve the collisions above are respectively called reader anti-collision algorithm and tag anti-collision algorithm.This paper focuses on the research of tag anti-collision algorithm.Firstly, the structure and working principle of RFID system are introduced. Secondly, on the base of a detailed description and analysis made for slotted Aloha algorithm and binary tree-based search algorithm, the following two tag anti-collision algorithm are proposed.By adding a modulo circuit to the tags to be recognized within query district, modulus based anti-collision algorithm(MBA) convert random response of the Aloha algorithm to determine slot response of reader according to the unique keyword within tags. MBA uses the lower bound (LB) algorithm to estimate the number of tags and assign frame value. Simulation results of Matlab show that MBA algorithm not only reduces the number of collision slot and idle slot in the process of tag identification, but also increases the throughput of the system.Hybrid anti-collision algorithm (HACA) groups the tags within query district, then, ADFSA algorithm and CTT algorithm are combined together. If tags collision happens within a slot, CTT algorithm will be used to process the situation. After all of the collision tags during the slot are identified, the reader begins to recognize tags in the next slot. Simulation results of Matlab show that this method effectively reduces the overall slots required for system identification tags and improves the throughput of the system.