Based On Multi-tree RFID Hybrid Anti-Collision Algorithm

Radio Frequency Identification（RFID）is the core component of the Internet of Things. Throughthe magnetic field or electromagnetic fields, the system uses wireless radio frequency manner fornon-touch communication, and reads the information from the tags of target object.When the reader sends the query signal to the range of signal coverage, multiple tagssimultaneously respond and compete one channel, resulting in each tag can not properly transmitdata information, tag collision happens. The tag collision will reduce the efficiency of tagidentification. In the RFID system, importance of resolving tag collisions is particularly prominent.Thus anti-collision algorithm research has gradually deepened.This thesis introduces the Internet of Things, the working principle and basic structures of RFIDtechnology firstly. Secondly, it introduces several typical anti-collision algorithms. Proposed twoimproved anti-collision algorithm based on classical algorithm: Grouping hybrid anti-collisionalgorithm（GHCA）, Based on the Q parameter and improved4-ary Query Tree hybrid anti-collisionalgorithm. Grouping hybrid anti-collision algorithm is based on the identification code bit "1"number of parity, tag will be divided into01group and10group. Through the secondary collisiondetection，the tag is identified by detecting collision position, thereby to reduce the collision slot, toavoid the generation of idle slots, and the total number of slots in the system are reduced. Throughmathematical analysis and simulation results show that GHCA can improve system performance.The principle of Based on the Q parameter and improved4-ary Query Tree hybrid anti-collisionalgorithm is that the Q parameter is adjusted by the front three consecutive occurrences of idle slots.Within the collision time slot, then the use of the improved4-ary Query Tree algorithm for collisiontag identification. The basic idea of the improved4-ary Query Tree algorithm is that reader sends aAND sequence to tags for logical AND operation. Then the reader sends a new detecting sequencewhich is according to the feedback results of logical AND. Thereby reducing the sum of frame slotsin the premise, the collision tags will be identified effectively.