Research On Tag Anti-collision Mechanism And Algorithm Of UHF RFID System

Radio frequency identification(RFID)technology is an automatic identification technology,by using the electromagnetic coupling or reflective transmission characteristics of radio frequency identification signals.RFID system is highly secure and adaptable to the environment.It can identify high-speed mobile items and support multi-target recognition.As one of the key technologies of IoT,RFID technology has become a hot research topic and has been widely used especially in manufacturing,transportation,sales logistics,public safety and many other areas.In the specific application,the identification of multiple tags at a time will inevitably lead to collision,seriously affect the performance of RFID systems.Therefore,in-depth study of stable and effective RFID tag anti-collision problem for improving the performance of RFID systems is of great significance.Firstly,the standard system and the structure and working principle of the RFID system are expatiated,and the existing tag anti-collision algorithm is analyzed and simulated.Then,according to the multi-tree anti-collision algorithm generating too many idle time slots,a multi-tree anti-collision algorithm based on mapping sequence(MSCMA)is proposed.The algorithm avoids null queries by introducing mapping sequence codes,and reduces the generation of collision slots.Theoretical analysis and simulation show that the recognition efficiency of MSCMA algorithm is up to 68%.Secondly,according to the According to the continuous distribution characteristics of tag IDs in a given application environment,an improved multi-tree algorithm based on collision-bit detection(CDIMA)is proposed.This algorithm can reduce the total number of time slots by locking the collision bits in a query response period.At the same time,the reader only need to send 3-bit data at a time in order to optimize the query order.So CDIMA algorithm significantly reduced the communication complexity.The experimental results show that the CDIMA algorithm achieves the best performance when tag IDs is continuously distributed,and the recognition efficiency is about 75%.Finally,based on the CDIMA algorithm,an adaptive algorithm based on choosing prefect N-tree(CPNT)is proposed.The algorithm can calculate the number of collision bits while locking the collision bits and determine the appropriate length of mapping tables.Transmission time delay is further reduced,thereby enhancing the overall performance of RFID systems.The simulation results show that the CPNT algorithm is better than the CDIMA algorithm when collision bits of tag ID is more than 54 bits.