Researches Of Tag Anti-collision Algorithm In RFID Systems

Radio Frequency Identification is an automatic identification technologyemerged in recent years, and widely considered as one of the top ten the mostimportant techniques in21st century. Tag anti-collision algorithm is the researchfocus on RFID system. While multiple tags sending data at the same time, signalsbetween tags will interfere with each other, reader can’t recognize any information,the tag collision occurs. Tag collision slows down identification process, decreasesthe recognition efficiency of the system. Therefore, tag anti-collision algotithm isnecessary to solve anti-collision problem and the improvement of identificationprocess.The background of the tag anti-collision algorithm, the constitution of RFIDsystem, the theory of data transmission and other relative theory are brieflyintroduced in this thesis. And, a detailed analysis of the various existing taganti-collision algorithms is carried out. The main innovations of this paper are listedas follows:(1) A novel anti-collision algorithm based on tag ID segmentation recognitionwas proposed (GPA). The GPA algorithm takes into account of the tag intensity andthe length of tag ID, GPA algorithm adopts grouping strategy to reduce the number ofresponsing tags, thereby reducing the collision. Tag ID is divided into two segments,firstly reader identifies the first segment of tag ID, go to identify the remaining part inthe tag ID, which can reduce the data transimition between tag and the reader. In thepaper, the best number of tags in a group and the best length of the first segment intag ID are resolved, and the performance analysis and simulations of the proposedalgorithm are carried out.(2) An enhanced binary tree based anti-collision algorithm was proposed (EBSA).In the practical application, tags are usually in the state of motion. EBSA takes intoaccount of it and the reader identifies tag groups successively according to the orderof tags entering recognition area. While identifying a tag group, in a query, tags senddata in succession accroding to the bit behind the query prefix in ID. Further, thereader stops to receive remaining data while detecting there are tw o collision bits. Thealgorithm was analysized, and simulated under VC6.0enviroment by using C language. The proposed algorithm can avoid the missing reading of tags and theidentification efficiency was significantly improved.