An Ti-collision Protxjcol In Large-Scale RFID System

Radio frequency identification technology(RFID) is a kind of automatic identification technology and it can transfers tags-data using radio frequency signal. As the core of the Internet of things technology, RFID has been widely used in many fields, and it has a big influence on the social and economic development. There are such problems, as the tag-collision, the Information security of RFID, the tag Locationing. These problems slow down the development of RFID. Especially in large-scale RFID system, the performance of recognition in RFID system decreases very obviously. Mainly in: 1) the current commonly used anti-collision algorithms' recognition efficiency is too low which needs to be improved. 2) The stability of current commonly used anti-collision algorithms isn't suitable while is applied to Supply Chain Management System and so on. 3) Principle of collision: current commonly used anti-collision algorithms are trying to avoid bit-collision, novel algorithm would try to use bit-collision in Manchester coding to recognize tags in order to reduce query-slotIn anti-collision algorithm, the Manchester code is used to confirm the position of the collision-bits, and it will be more efficient to distinguish tag ID while making a good use of collision-bit information. In this paper, we use Manchester coding to confirm the position of the collision-bits and based on collision tree algorithm(CT), we propose a novel anti-collision algorithm called Multi-Response collision tree algorithm(MRCT). In MRCT, we divide the identification-cycle into two parts, including the query-cycle and M response-cycles. In this way, we can reduce the query-cycle in the whole identification-cycle. Otherwise, we propose an improved adaptive collision tree algorithm(IACT) in this paper. The improved algorithm reduces idle time slots which occurs in adaptive collision tree algorithm(ACT) by optimizing the prefix-query. After all, we propose dual-response improved adaptive collision tree algorithm(DIACT) that dual-response mechanism is proposed in DIACT, and the response-cycles are divided into two sub-cycles, so two group tags with sign-bit ‘0'or'1' would reponse the same query respectively and independently. In this way, DIACT solve the problem that IACT can't identify two tags in just one query-cycle if it's not just one bit is collided in the collision slot. By mathematical analysis and simulation, it proves that the proposed algorithm reduces the time complexity and improves the efficiency of recognition in RFID system. Especially in large-scale RFID system, it will have a better performance.