Analysis And Research Of Tag Anti-collision Algorithms For UHF RFID System

Radio frequency identification(RFID)technology is an automatic identification technology by using the reflective transmission characteristics of radio frequency identification signals.Comparing with the traditional bar code technology,RFID technology has higher security.RFID can adapt to different environmental needs and identify high-speed moving objects.Also,it can support a large number of unique user ID.With these benefits,RFID technology can dramatically improve automated management processes in all areas,such as logistics and supply chain visibility,item tracking,transportation and more.In practical application,the problem of tags collision severely restricts the performance of RFID technology.Therefore,it is of great significance to study tags anti-collision algorithms with lower complexity and better stability under the condition of acceptable cost and technology realization.Firstly,the thesis gives a brief description of the system structure and working principle of the RFID system,and simulates the common tags anti-collision algorithm.Then,in view of the low throughput of traditional frame slot ALOHA algorithm,the thesis proposes an improved frame slotted ALOHA algorithm with the query tree(IQFSA algorithm).The algorithm combines the advantages of muti-tree algorithm and frame slot ALOHA algorithm.The ALOHA algorithm's "starvation" problem is effectively solved by using multivariate query tree.Simulations show that the throughput of this algorithm can reach over 43%.Secondly,the thesis also proposes a dynamic frame slot ALOHA algorithm combined with collision detection(CDFSA algorithm).The collision detection technology and double response mechanism are used in this algorithm to identify collisions between two tags in ALOHA algorithm through a single query.It can effectively improve the recognition efficiency.Finally,on the basis of the existing collision tree algor ithm,the thesis proposes an improved collision tree algorithm based on mapping groupings(ICTMG algorithm).Firstly,a mapping coding scheme is proposed.ICTMG algorithm will use different mapping coding scheme by the collision bits.Idle query can be completely removed by the mapping code.Theoretical analysis and simulation show that the throughput rate of the algorithm can be more than 67%.With the non-collision bits increase,the algorithm will also have performance rising.