Research On Anti-collision Algorithm Of Multi-Reader In RFID System

With the development of information and industrialization,the Internet of things,as a key link,has been widely used.Radio Frequency Identification(Radio Frequency Identification,RFID)technology is one of the main technologies of the Internet of things,which has been widely used in a variety of scenarios.It is mainly used to realize the collection of item information,automatic identification,identity authentication and so on.In some RFID application scenarios,it is often necessary to deploy multiple readers in order to cover the entire regulatory area.In the environment where multiple readers coexist,how to prevent communication conflicts or communication collisions between readers is worth studying.Because the collision of the reader will worsen the efficiency of the whole system.However,the existing reader anti-collision algorithms can not solve the problems of low system efficiency and long recognition time when there are too many collisions between readers in large-scale scenes.In view of the above problems,this thesis has done the following work:(1)An anti-collision algorithm based on minimum reverse weight reader is proposed.By adjusting the power of the reader and combining with the reader time-domain scheduling strategy,the algorithm can eliminate the collision area between readers to the maximum extent,so as to reduce the scheduling time.The algorithm adjusts the power of each reader according to the minimum reverse weight,and takes the union of the recognition range of each reader to cover all tags as the constraint,so that the collision area between each reader is minimized.This scheme can effectively eliminate the collision between readers,reduce the energy consumption of readers to a certain extent,and there is no problem of tag omission,which lays a foundation for the scheduling of subsequent readers.In the process of reader scheduling,considering that the collision between readers is a probability problem,the concept of collision threshold is proposed,and the independent set method is used for time domain scheduling.It simplifies the scheduling process,reduces the complexity,increases the number of parallel work readers,and finally improves the efficiency of the system.(2)A reader anti-collision algorithm based on forest-like structure is proposed to make up for the shortcomings of the reader anti-collision algorithm based on minimum reverse weight.The minimum reverse weight reader anti-collision algorithm needs to use the tree structure to calculate the reader power combination that meets the condition of full tag coverage.With the increase of the number of readers,the combination results that need to be traversed will grow exponentially,resulting in a surge in computation.In the start-up stage,the reader anti-collision scheduling algorithm based on forest-like structure can transfer information between readers by setting control channels and setting collision queues to store collision information between readers.The collision threshold is set to simplify the collision relationship between readers and generate a forest-like structure map according to the simplified reader collision.With the help of the redefined reader priority algorithm,the maximum independent set of the reader is obtained by traversing the quasi-forest structure map.At this point,highly independent readers begin to work in parallel.In the process of running the follow-up system,each reader updates the status of the collision queue in real time by parsing the information of the control channel,and joins the work queue in time without collision,which ensures that the reader working in parallel is a large collection of collision-free readers.This scheme can greatly simplify the computational complexity of the system,reduce the waiting time of each reader,and improve the efficiency of the system.Finally,through simulation experiments,the performance of the two algorithms proposed in this thesis is compared with the classical reader anti-collision algorithm,which proves the high efficiency of the two algorithms proposed in this thesis.