Research And Performance Analysis Of Adaptive Identification Anti-collision Algorithms Of RFID System

Radio frequency identification technology is a kind of non-contact automatic identification technology by electromagnetic waves in the air for data transmission.RFID has a lot of advantages of high efficiency,large storage,reliability,long identification distance,etc.RFID is one of the core technologies of the Internet of things(IoT),with the development of the Internet of things technology and application,which is applied in many fields widely,including entrance guard,transportation,foot safety and logistics etc.In the RFID system,there are two types of collisions,one is reader collision and the other is tag collision.But readers have strong ablitiy of information processing by itself,so at present,the research is focused on the tag collision.Developing a good anti-collision algorithm to reduce and avoid collisions is of great significance for improving the overall performance of RFID system.The existing anti-collision algorithm mainly included the probabilistic anti-collision algorithms based on ALOHA and the deterministic anti-collision algorithms based on the binary tree.In this paper,some improvement and innovation have been done on the classic anti-collision algorithms based on the binary tree and ALOHA.The mainly improvement and innovation points are as follows:(1)Based on dynamic frame-slotted ALOHA algorithm and binary search tree algorithm,a dynamic framed binary tree(DFBT)anti-collision algorithm is presented.Vogt algorithm is adopted to estimate tags number,then the dynamic frame slotted ALOHA(DFSA)algorithm is used to identifying a part of tags by choosing appropriate time slot number,and then the unidentified tags are extracted and the highest collision bit is judged by readers.Finally,the highest collision tags are grouped by the collision bit within the binary search tree(BST)algorithm.Simulation results show that DFBT algorithm can improve identification efficiency and stability which reduces the total time slots and the cost.When tags number is about 1000,identification efficiency of the DFBT algorithm is about 64%.(2)Combined with the multi-tree algorithm and improved it,we proposed an optimization prefixed adaptive hybrid tree(OPAHT)anti-collision algorithm by optimizing the prefix sent by readers.The OPAHT algorithm is based on the information of the collision bit,and it auto-adjusts the query prefix to choose the search tree branches.When the highest two collision bits are discontinuous or there isonly a collision bit,binary tree search algorithm is used to identify the collision tags,and when the highest two collision bits are continuous,identifying the collision tags by quadtree algorithm,thus it avoids some idle timeslots.The results of the simulation show that when the number of tags is about 1000,the system throughput still maintains about 65%,also OPAHT algorithm can reduce the collision timeslot and total timeslot,thus it can reduce the communication complexity.