The Researches Of Tag Anti-collision Algorithms Based On Aloha In RFID Systems

Tags reading anti-collision technology is one of the most critical technologies inthe RFID systems, that is, whether the reader identify the tag correctly when there aremultiple tags sending data to the reader simultaneously. With the development ofRFID technology, tag-collision is becoming one of the serious problems needed to besolved. Tag anti-collision algorithms include random algorithm and deterministicalgorithm. The identification accuracy of deterministic algorithm (mainly tree searchalgorithm) is relatively high, but it is difficult to realize because of high requirementsfor the hardware. Random algorithm is mainly based on Aloha algorithms, theexisting Aloha algorithms have low system throughput, which do not identify the tagin a state of conflict and is unsuitable for the situation of large number of tags.After analyzing and comparing of the existing random algorithms, a new taganti-collision algorithm which based on the group Aloha algorithm---NGFSA isproposed in this paper. The innovative points of this paper include:(1) The group adjustment method of the existing group algorithm is optimized;the optimized algorithm whose system throughput maintains a stable state, it alsoavoids wasting time slot in the group;(2) After the analysis of the existing random algorithms, a new improved groupAloha algorithm---NGFSA is proposed based on the previous studies in this paper,which uses the ideas of stack and re-groups the tags which are in the conflict time-slot,it combined with the operation of stack to identify the conflicting tags step by step.The result of simulation shows that, this new algorithm which is not only suits forthe situation with a large number of tags, but also able to identify all the tags in theconflict time-slot,further improving the system throughput.