The Research Of Tag Anti-collision Algorithm Based On The Dynamic Framed Slotted ALOHA

Radio Frequence Identification(Radio Frequence Identification, RFID) technology is one of the core technology in IOT which uses radio frequence signals to achieve the goal of automatic identification. Because the technology has the advantages of no manual operation, non-contact automatic identification and the recognition speed. Moreover, make its rapid development in science and technology of contemporary. But in the process of communication with the reader and tag will induce collisions between data information when multiple tags simultaneously respond to the reader, that lead to tag misreading and leakage of information to read, and impact the application of RFID technology.This article mainly studies the anti-collision algorithm that solveing the problem of tag collision. Firstly, studies the class of the typical ALOHA anti-collision algorithm, expounds its working principle, implementation process and the advantage and disadvantage of each type of algorithm. Aiming at the insensitive of timeslot adjustment in dynamic frame slot ALOHA algorithm and the high rate of collision problem in the group of grouping DFSA algorithm, puts forward the corresponding two different improvement schemes.The first one is to the occasion of small number of tags, proposed the dynamic framed slotted ALOHA anti-collision algorithm based on golden section. Through the analysis of the typical dynamic frame ALOHA tag anti-collision algorithm shows that there are a lot of idle slots and collision slots, and the timeslot adjustment in frame depends on the estimated number of tags, and that is not conducive to rapid adjustment of timeslot and influences the recognition efficiency of system. Therefore, this paper based on the probability distribution of the tag arrives in the range of reader and combined with golden section method of thought, by setting the threshold condition to dynamically optimize the frame length. The simulation results show that, this algorithm reduces the number of empty slots and total slots, effectively improves the recognition and slot utilization efficiency of system.The second one is to the occasion of large number of tags, proposed the hash grouping based dynamic framed slotted ALOHA anti-collision algorithm. This algorithm mainly aim at the application limited of DFSA and the collision problems caused by the large number of tags in grouping DFSA, and by analyzing the tag distribution under optimal recognition efficiency, a new anti-collision algorithm of dynamic frame slotted ALOHA based on hash function grouping is proposed. Firstly, according to the characteristic of the binomial distribution and probability theory, a new estimation method is used to estimate the number of tags, then tags are divided into appropriate groups by constructing a hash function, and identified individually. The simulation results show that, the proposed algorithm can reduce the quantity of responding tags in each group and the probability of tag collision. Compared with existing algorithms, the advanced algorithm is easyto achieve, and can get high and steady identification efficiency of system, lower the computational complexity and shorten the tags identification time.