Tree switching algorithm for efficient passive RFID tag anti-collision remedy

Abstract

Radio Frequency IDentification (RFID) is the wireless identification technology using RF waves. In the research areas for RFID systems, the tag anti-collision algorithm is the important issue for reliable identication. Tag anti-collision algorithm solves the tag collision problem that multiple tags atempt to send their IDs. Tag anti-collision protocols is classified into tree based algorithms and ALOHA based algorithms. In this thesis, we consider only the tree based anti-collision algorithms, since the tree based tag anti-collision algorithm achieve 100% read rate. In this thesis, two schemes is proposed for improving existing algorithm ,single-slotted tree switching algorithm, and bi-slotted tree switching algorithm. First of all, single-slotted tree switching algorithm, which switch the 4-ary query tree algorithm to the binary query tree algorithm, is proposed. In single-slotted tree switching algorithm, the reader starts tree searching with 4-ary query tree algorithm. When one tree level is ended, if collision probability is less than threshold (0.75), the reader switches the 4-ary query tree algorithm to the binary query tree algorihm from next tree level, otherwise the reader remains the 4-ary query tree algorithm. Using this proposed algorithm, the iteration and required bits efficiency is 10%. Next, bi-slotted tree switching algorithm, which uses bi-response slots, is proposed. In this proposed algorithm, all process is same as single-slotted tree switching algorithm excepting using bi-response slots. Using this proposed algorithm, the iteration and required bits efficiency is 43% compared with the binary query tree algorith. In other word, the identification time is reduced by 43% using this proposed algorithm rather than using binary query tree algorithm. In conclusion, the proposed algorithms improve the tag identification speed than the existing anti-collision algorithm.