Research Of Multi-tags Anti-collision Algorithm For RFID System

Radio Frequency Identification, short for RFID. It is a kind of technology, which utilizes the radio frequency signal to transmit the non-contact type information between the reader and the tag for the purpose of identifying tag. Its application is increasingly widespread. However, when people use RFID system to complete the identifying task,they often encounter problem of multi-tags anti-collision data collision. The algorithm for solving the problem of data collision is called multi-tags anti-collision algorithm, which is mainly divided into random anti-collision algorithm and deterministic collision algorithm. The more classic random anti-collision algorithm contains pure ALOHA, time slot ALOHA, frame time slot ALOHA, dynamic frame time slot ALOHA algorithm.The more commonly used deterministic anti-collision algorithm includes basic binary tree anti-collision algorithm, dynamic binary tree anti-collision algorithm, backward binary tree anti-collision algorithm and backward dynamic binary tree anti-collision algorithm.Firstly, researchs advantage and disadvantage of two more commonly-used algorithms:ALOHA algorithm and binary tree anti-collision algorithm, then uses Matlab to simulate analyse the number of queries, the system throughput, the amount of transmission information. ALOHA algorithm has certain degrees of randomness with leakage reading of some tags. While binary tree anti-collision algorithm can avoid the happening of leakage reading in labels, but when the number of tags is large, the speed of recognition algorithm will become slow. In order to improve the identifying speed of the binary tree anti-collision algorithm when a large number of tags exist, this article presents an improved algorithm based on jumping dynamic binarytree anti-collision algorithm. The algorithm improves readers’identifying efficiency by using the methods of exclusion and non-collision. It also verified the performance advantage of the improved algorithm by the simulation comparisons of Matlab with the improved algorithm and jumping dynamic binary.Secondly, presents a hybrid algorithm through combining features of dynamic frame time slot ALOHA algorithm and jumping dynamic binarytree anti-collision algorithm. In this chapter, the tag estimation model which was proposed by using Volt enables Hybrid algorithm to make full use of communication time slot, as well as improving the system efficiency of anti-collision algorithm. In this paper, from formula derivation and Matlab simulation analysis, it can be concluded that the system throughput rate of hybrid algorithm improves obviously.Finally, apply CycloneⅡ FPGA deviceto design backward binary tree anti-collision algorithm. It contains Mmanchester decoding module, LIFO stack module, state machine module controling algorithm of reader module. It proves the validity of implementingthe algorithm through simulation waveform of Quartus Ⅱ design.At lastit generates the function schematic graph of each module for implementation.