The Research And Realization Of Time-frequency Analysis Based On Long-distance RFID Location

Internet of Vehicles, or Telematics, refers to the interdisciplinary field that encompasses telecommunications, vehicular-related technologies, road transportation, electrical engineering (sensors,instrumentation, wireless communications, etc.), and computer science (multimedia, Internet, etc.). It has the partial capability and future potential of monitor the location, movements, status and behavior of every single vehicle, thus improving the efficiency and security of public transportation. Due to the increasing needs of vehicles in daily life,telematics and other related research has been developing rapidly in recent years. Mobile location system is an important part of telematics application. While the development and application progress of GPS, the Global Positioning System, enriches the mobile positioning part of telematics, it also raises the further expectation of mobile position system.In the future, positioning hardware is expected to be more minimized and power-saving, with higher noise immunity, location accuracy. As a method that frequently draws attention recently, Time-frequency Analysis method is applied in many fields of research, however the application of time-frequency analysis method in mobile positioning is still stalls in theory.Based on the RFID positioning theory, this paper has introduced the time-frequency analysis method as a backup resolution of GPS positioning. Using RFID positioning system based on RSSI algorithm and replacing the original based-band I/O filter with 2-dimensional time-frequency distribution, this method is capable of detecting the main lobe in frequency domain as well as the time delay in time domain, thus improving the location accuracy and noise immunity. To reduce the negative effect of cross-terms in time-frequency distribution, this paper optimized a core function in Cohen class with Renyi entropy calculation.In addition, due to MATLAB simulation, this paper compared the original and optimized distribution's core function with different parameters,whose results confirmed that the optimized distribution has better cross-term disturbance immunity than the original distribution.Based on the results of the simulation, this paper designed and practiced series of actual experiments which has tested the RFID mobile positioning ability. The results of the experiments have showed that the error is within 5 meter when the distance between the antenna and the target is within 50 meter, and that the error is within 8 meter when the distance between the antenna and the target is within 100 meter.