| Radio frequency identification(RFID) is a non-contact automatic identification technology, it can automatically identify the target and get relevant data by radio-frequency signal. Because of its some advantages, such as reading data directly without touching, working in harsh environment, the penetration ability, and the ability of identify multiple targets at the same time. It is considered as the best technology to replace bar codes. With the introduction of the concept "Smart Planet" and the extensive promotion and application of the "Internet of Things" technology, RFID technology as one of the core technology in IOT, also has unprecedented rapid development and wide application.In recent years, with the rapid development of RFID technology, The anti-collision technology, which is one of the key technologies in RFID has also become a research hotspot. Multi-tag identification problem is an important issue in RFID technology and applications, including the product development process. With the development of RFID technology, the problem of multi-tag identification is also constantly improved and perfected, However, due to the complexity and uncertainty of the multi-tag identification, the performance in the application of the multi-tag identification is not satisfactory, the technology research and product improvement is still ongoing.In RFID applications, although there are many impact factors restricting the reader’s efficiency of the multi-tag identification. In order to enhance the reader’s multi-tag reading efficiency, according to EPC protocol in this paper:First, analyzed the multi-tag collision detection technology in RFID system, and made simulation with matlab, the results showed that the false positives of collision detection is less than10%.Second, analyzed and simulated the anti-collision algorithm inside of the reader in the practical application, and put forward the drawbacks in the practical application. Making mathematical modeling to analyzed the conditions for adjustment Q value, study and simulate the algorithm based on EPC protocol, at the same time, improved the protocol’s algorithm in grouping the tags, and discussed the operability of the grouping algorithm.Third, explore the problem about number estimation of the remaining tags, Simulate and Analyze the property of the slot-count(Q) selection algorithm which is on the basis of the EPC protocol, and the Poisson estimation methods, then summarize the algorithms’ advantages and disadvantages, propose a new method of multi-tag number estimation to resolve the problem of low accuracy of multi-tag estimation, and the performance of the algorithm has been tested and verified;Fourth, analyze communication rate and the communication process between reader and multi-tag, summarize the Calculation formula for multi-tag communication time, and on this basis to analyze the impact of the rate of multi-tag identification system under different link frequency; improved the mind of the new multi-tag estimation algorithm, and make theoretical analysis and validation for its practical application. Further proposed:under the EPC protocol, coreader send the QueryAdjust command continuously, and reduce the number of sending QueryRep command, the simulation result show that the multi-tag reading time can be shorted by this method.Fifth, use speedway reader to do multi-tag reading test, summarized and analyzed the test datas, propose a multi-tag identification algorithm in a new idea, called speedway algorithm. Send the truncated command if the tags have the same EPC, at the same time dynamically determine whether a premature end to the identification in a polling cycle, and open next new polling cycle. Matlab simulation tell us the new algorithm and the speedway algorithm both have a high performance, the truncated command in speedway algorithm is better.Finally, summarized the algorithms studied in this paper, and propose the topic that need further studied. |
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