Research On Positioning Technology Of Internet Of Things Based On RFID

With the advent of the Internet of Things(Io T)and the rapid advancement of information technology,the demand for intelligent services based on high-precision positioning is growing,posing new demands and difficulties to current positioning technologies.Although the Global Navigation Satellite System(GNSS)can now achieve high-precision positioning in a large outdoor area,it is difficult to avoid positioning interruption and large positioning errors in areas such as viaducts,tunnels,large buildings,lush vegetation areas,and indoors that employ GNSS.Thanks to the widespread use of Radio Frequency Identification(RFID)in Io T,RFID-based positioning technology offers a wide range of market application prospects and development benefits,and has piqued the interest of researchers and workers in a variety of industries both at home and abroad.This paper uses frequencyhopping technology to realize the RFID ranging method using Multi-frequency Continuous Wave(MFCW),and studies the ranging and positioning method based on phase difference information,in order to address the existing problems in RFID-based positioning utilizing carrier phase.Finally,the tag backscatter information is collected through Universal Software Radio Peripheral(USRP)hardware platform,and the ranging and positioning algorithms proposed in this thesis are validated and analyzed.The following are the specific contents:1.This thesis explores the range estimate approach based on MFCW phase information as well as the hyperboloid location method based on phase difference information.To begin,the theoretical basis of phase ranging based on multi-frequency continuous wave signals is derived using the relationship between range estimation and phase,frequency interval,and phase error in single frequency and dual frequency signals,and the Constrained Minimum Mean Square Error(CMMSE)is used to solve the ambiguity of the whole period number caused by the periodicity of the phase.Using numerous frequency signals improves the accuracy and robustness of phase ranging.The effect of frequency bandwidth and number of frequencies on the ranging effect is then simulated and examined.A hyperbolic-based geometric positioning algorithm is then applied based on the range difference estimation results of MFCW phase difference information.According to the mathematical description of the distance information received from the phase information,this approach may be applied to the processing process of using the phase difference to obtain the distance difference information,such that the hyperbolic geometric property of the distance difference can be used to complete the positioning.This thesis employs an improved processing method to speed up the algorithm execution process of solving the nonlinear equation for this geometric positioning method.Finally,simulation is used to demonstrate the results of the range estimate algorithm and the positioning algorithm based on phase difference information.2.This thesis uses general software radio peripherals to send the specified transmission frequency combination,activate the tag,and collect the tag reflection signal based on the RFID communication protocol.The phase measurement of a tag’s backscattered signal is then finished using this platform,and a positioning test scenario is designed to validate and analyze the suggested algorithm’s actual effect.Experiments validate the effectiveness of phase acquisition and the system’s feasibility.The experimental results showed that in a static condition,the system can achieve a good range effect.In the case of probability,high-precision positioning results can be accomplished by utilizing numerous tags to find the reader antenna.However,in the case of many tags,the RFID communication process’ s tag collision problem needs to be addressed further.