Research And Application Of RFID Anti-collision Algorithm

All the applications using RFID are facing the same problem: the mutual signal willaffect each other to make the reader can’t get effective message when multiple tagscommunicate with the reader. We call it signal collision and algorithm to solve theproblem anti-collision algorithm. At present, the anti-collision algorithms are mainlydivided into definitive anti-collision and probabilistic anti-collision algorithm. ALOHAis a typical probabilistic anti-collision algorithm, which mainly includes ALOHA, timeslot ALOHA, frame slot ALOHA and dynamic frame slot ALOHA. Tree-based searchalgorithms are definitive, which mainly includes binary tree search algorithm anddynamic binary tree search algorithm as well as returned binary tree search algorithm.First, the paper simply introduces the advantages and disadvantages of the existinganti-collision algorithm. ALOHA algorithms are easy to be realized, but when thenumber of tags is larger, the efficiency of the system will be lower. Binary searchalgorithm has higher identity efficiency while the identity rate is lower.To improve the efficiency when the number of tags is larger, the paper provides anADFSA algorithm based on ALOHA. The algorithm shields the resource waste causedby empty time slot in DFSA using auxiliary sequence. At the same time, the algorithmimproves the efficiency when the number of tags is large by fixed group that reduces thenumber of tags of being identified at the certain time.Due to the limit of hardware facility, usually it can be divided into256groups atmost. Therefore, with the increasing number of tags, the efficiency will become lowerand lower. Thus we can see that the algorithm using fixed group will not be affected bythe number of tags. So, combining the advantages of DBT and DFSA, we present anadaptive group anti-collision algorithm–ADBT. ADBT will divide tags into groupsusing the corresponding bit to improve the adaption to the number of tags.By simulation, ADFSA and ADBT provided in the paper are all better than theexisting anti-collision algorithms. Meanwhile, the paper proves the superiority andpracticality from throughput rate and total time as well as communication trafficcombining the project “Joint Technical School Student Attendance System of Dongguan,Guangdong”.