Study Of UHF Reader Anti-collision Technology For Dense RFID System

Radio frequency identification technology is a kind of non-contact automaticidentification technology which has many advantages. In recent years with the rapiddevelopment of this technology, it has been widely used in a number of areas and moreand more applications need to deploy a large number of readers and tags, resultingcollision problem in a lot of tag reading process, in which case, relying only on the taganti-collision technology to improve the efficiency of the system is not enough, we mustsolve the reader collision problem in the system at the same time, in order to improvethe efficiency of the system.This paper aims to address reader anti-collision problem and take UHF RFIDreader anti-collision identification technology under intensive mode as an object ofstudy.The basic theory of reader anti-collision is discussed. Then the novel andimproved algorithms are proposed:1. A novel size of coordinating range is proposed by analyzing the interferencerange of the reader, and the reader hidden terminal and exposed terminal problem. Itensures coordination range within a more reasonable range, which will help theanti-collision algorithm based on coordination-effective implementation;2. A novel power control strategy is proposed by gradually approaching the optimalpower and reading distance under a limited number of times. It reduces the collisionsbetween the readers and much simpler than other power control strategy;3. A novel decreasing backoff strategy is proposed considering the characteristicsof the RFID system. With the increase in numbers of backoff, it reduce the backoff time,and the backoff time is not exactly the same when the number is same, which furtherreduces the reader collision problem;4. A novel reader anti-collision algorithm is proposed based on the combination ofpower control and coordination. New power control strategy and backoff strategy isapplied to the new anti-collision algorithm. Simulation results show that the algorithmcan efficiently read the tags in intensive reader environment.