Study And Simulation Of Rfid Anti-collision Algorithm

RFID (Radio Frequency Identification)is an important branch of automatic identification technology, which has been under rapid development and applied in many fields in recent years . To solve multi-tag collision is an important step of RFID system. This paper concerns the multi-tag anti-collision algorithm and learns the key problems of the RFID system. The main works are as follows:Firstly, this dissertation reviews the RFID background, the significance and current global and domestic status of RFID study. The detailed composition and principle of RFID systems are introduced. RFID systems can be classified by different aspects of tags, e.g., tag power-supply modes, tag working frequency, modulation method of tags, readability of tags, and the induction distance of tags. Also the basic theoretical knowledge of RFID, such as RFID energy and the signal transfer process, and antenna technology are explained brieflyParticularly, this dissertation introduces the ALOHA algorithm, one of the most popular TDMA (Time Division Multiple Access) algorithm nowadays. We give a description of the working principle, the advantages and disadvantages of various ALOHA algorithms, which include pure ALOHA, Slotted ALOHA, FSA(Frame Slotted ALOHA), and DFSA(Dynamic Frame Slotted ALOHA). By Matlab simulation of all of these algorithms, it is proved that when the frame length equals to the number of tags, the efficiency of the algorithm is the best. So the key issue is to estimate the number of tags in the system. We then present a method which is to estimate the tags. Combined with the DFSA, we propose a new anti-collision algorithm which is based on the ALOHA. Furthermore, we compare the theoretical analysis and simulations to improve the algorithm.Finally, an important branch of TDMA - binary search algorithm is studied. We describe the working principles of binary search algorithm, recoverable binary search algorithm, and dynamic binary search algorithm. We present several practical examples for investigating these algorithms. In this regard, we put forward a concept of"lock bits"which combines the merits of all the three algorithms, and propose an improved algorithm. To deal with the conflict, we just lock the bits that are in confliction and invoke a step back strategy, then use a confliction avoiding scheme for the bits that are locked. Performance analysis and simulation on the proposed algorithm show that it is obviously better than the binary tree search anti-collision algorithm and the dynamic binary search algorithm in terms of reader call number, energy consumption, transmission delay, and system throughput.