Research On RFID Anti-collision Algorithm Based On Collision Bit Detection

Radio Frequency Identification(RFID)is a technology that uses the spatial coupling of radio frequency signals to realize automatic identification,and is recognized as one of the most promising information technologies in the 21 st century.RFID has the advantages of non-contact reading and writing,strong environmental adaptability,reusability,and high degree of automation.It is widely used in logistics inventory,warehouse management,financial payment,tracking and positioning and other fields.The most critical problem in RFID technology is multi-tag identification,but since a single reader has only one shared wireless channel,when multiple tags send data to the reader at the same time,a collision will occur,causing the reader to The tag data cannot be read effectively,and the solution to this problem is the Anti-collision Algorithm.For the anti-collision algorithm,the protocol standardized by EPC Global RFID is mainly based on two general strategies,one is the random anti-collision algorithm based on ALOHA,and the other is the deterministic anti-collision algorithm based on binary tree.The deterministic anti-collision algorithm is researched and improved.The relevant research results are as follows:(1)Comparative analysis of QT algorithm,A4 PQT algorithm and GBAQT algorithm,for their problems such as long recognition cycle and low throughput rate.An Adaptive Query Tree Based on Mapping Sequence Code(MAQT)anti-collision algorithm is proposed.The MAQT algorithm introduces the prefix detection mechanism and the adaptive multi-fork tree mechanism,only pays attention to the three consecutive bits headed by the highest collision bit,adaptively selects the fork mode according to the characteristics of the collision bit,and uses the prefix detection mechanism to accurately determine the query prefix to avoid Idle time slots,reduce collision time slots.The simulation results show that the MAQT algorithm can effectively reduce the total number of time slots and improve the system identification efficiency.(2)Aiming at the problem that the query command in the traditional double prefix matching(DPPS)anti-collision algorithm can only carry two query prefixes fixedly.A Query Tree Based on Dynamic Prefix Matching(DMQT)anti-collision algorithm is proposed.The DMQT algorithm adds a Hamming re-prefix determination stage,and uses a quad-tree method to determine all possible prefixes carried by tags,thereby Avoid idle time slots.In addition,the idea of dynamic prefix matching is used to dynamically determine the number of query prefixes that need to be sent out in the next query time slot according to the information detected by the reader,further reducing the number of queries and improving the performance of the algorithm.The simulation results show that the DMQT algorithm can effectively reduce the total number of time slots and improve the system identification efficiency.