Rfid Multi-tag Anti-collision Technology

For wireless communications in the field of ultra-high frequency long-range Automatic Identification System,Applications have begun to EPC GEN2 (the second generation of electronic goods encoding) reader. In the design of EPC GEN2 reader, tag anti-collision algorithm of inventory of multi-electronic tags is an important aspect. Multi-tags anti-collision algorithm in EPC GEN2 has two main indicators: Reliability and efficiency. But throughout the anti-collision algorithm, to determine the Q value is the most critical aspect. In the existing algorithms have been made public, there are two types of more general algorithm. The first category, the dynamic frame slot algorithm whith variable c parameters. Q value of the method used to be determined by the flow: Initialize Q value to 4,and constantly use the Query command to search, According to whether there is tag response to the read to plus or minus Q values. By the modeling analysis and practical experience shows that: In such methods at a number of heavy tag, the tag identification efficiency is very low. The second type is tag estimation algorithm (including the minimum estimation of law, Poisson distribution estimation algorithm, space-point approximation method to estimate, etc.), That is, at the end of each frame on the basis of the number of collision times happened in last frame (collision slot), the success of electronic tags to identify the number of (successful slot) and electronic tags do not return the number of (empty slot) to estimate the unidentified quantity of electronic tags, accordingly then select the optimal length of the next frame(time slot number). By the modeling analysis and practical experience, it show that because such methods estimate the number of the tag , it can't be real-time dynamic tracking the change of the tag Q value. And it results in inefficient tag identification.This thesis aimed at resolving the problem of the low efficient of the many existing methods of inventory electronic tag, combining with the advantages of estimates of the number of tags and random frame slot algorithm for each other's advantages. Research methods: Making use of finite state machine theory and matlab / simulink / stateflow state machine model in the set up tag and reader communication model, two types of mainstream algorithm through several representative simulation algorithm, to find out their respective advantages and disadvantages, and then integrate the advantages for we developing new algorithms. This article mainly covers the job: 1. Setting up EPC GEN2 CLASS1 apply to the reader and tag communications platform.2. Deducing dynamic frame-slot algorithm and random frame slot indicator algorithm theory.3. Investigation and analyzing dynamic frame-slot slot-frame algorithm and random algorithm.4. Combination of dynamic frame-slot algorithm and tag estimation algorithm and innovative new multi-tag identification method.