The Application And Study For Radio Frequency Identification Technology In Direction Sensing

The radio frequency identification(RFID)technology,one of the core technologies of internet of things(IOT),has been used widely in many fields.As a non-contact automatic identification technology,RFID realizes the data communication between the reader and tags with the use of wireless radio frequency signal,which can be used to collect the information and automatic identification of the target.The RFID technology has many advantages,such as,the high recognition speed,accuracy and identification distance,high safety and good environmental adaptability,etc.In some critical areas of RFID technology,many major breakthroughs have been obtained.However,in the practical applications,many technical problems of RFID technology are still being existed,such as,the filtering efficiency of the reader,multi-tag collision problem,the effect of the label attached,electromagnetic interference of the application environment,and the multipath problems.The paper introduces the development history,the basic model,and the development status at home and abroad of RFID technology.And a more detailed description of the structure and components of a typical RFID system are discussed.Finally,some researches for the above issue are discussed.Firstly,a novel method for the orientation sensing is presented by utilizing the technology of RFID and polarization diversity.Two tags are attached on the target;then,the orientation of the target can be obtained by a simple statistical estimator of the signal strength of the tag replied.The results show that,the mean estimated error of orientation sensing is 10.1°.To study the performance of RFID technology under fading channels,this article has analyzed its modulation and coding technique,and derived the bit error rate(BER)of backscatter modulation.Then the tag error rate(TER)under the Nakagami-m fading channel was derived,and some simulation results for different fading and coding parameter were showed and analyzed.The Results show that the larger the parameter of fading and repe tition coding,the lower the TER.Secondly,the data source of traditional reader-filter method is extensive,which reduces system filtering efficiency.Based on the methods of reader-filter and RFID tag population management in air-protocol,a geometrical filtering algorithm for air-protocol is derived.Combining with the traditional reader-filter,a complete system filtering method is presented.Utilizing the probabilistic model of inventory operation and the means of analytical filtering time measurement,the performance of the method proposed is evaluated.The simulation results show that the novel system filtering method reduces the overall filtering time by almost 50% compared to the reader-filer technique.Finally,based on the basic principle of RFID and antenna scattered theory,an improved two-port network link model in real environment of UHF RFID system is proposed.Based on virtual instrument technology,a simulation and test system of RFID system link is established.Through simulation test,the tag‘s absorbed power and BER in real environment can be get,which validated the environment factors effecting on the performance of RFID system.