Design And Research Of Indoor Positioning System Based RFID

RFID (Radio Frequency Identification. RFID) technology, an automatic identification technology, uses radio frequency electronic device transmits RF signals that recognize target automatically and access to relevant data through space coupling and can write new information into the identity device of the target. With the development of economy in recent years, wireless location technology, especially indoor wireless location technology that possess broad application potential in wireless navigation, warehouse management, logistics and transport, intelligent building has drawn more and more attention. However, due to indoor multipath effects and other factors, the traditional location technologies gain poor indoor location accuracy or even total failure. Therefore, the RFID becomes a preferred indoor location technology for the characteristics of non line of sight and non-contact.The effect of indoor multipath environment, scattering, diffraction, random noise and other factors cause a decline in accuracy. Thus, this paper focuses on how to eliminate environmental factors and to improve location accuracy. The basic principle of RFID technology and the algorithm of indoor wireless location were described first and then improvements were made on the basis of LANDMARC location algorithm. Main works are as follows:First, the RFID technology and development of indoor location technologies were introduced, a detailed description of the basic structure of RFID system components and key technologies was made, the typical indoor location system is studied and a comparative analysis of characteristics of various wireless indoor location technologies is given.Second, those methods based on signal time of arrival (TOA). signal time difference of arrival (TDOA) and signal azimuth of arrival (AOA) were described in detail. Also, the advantages and disadvantages of various location methods were compared. In combination of path loss model and the LANDMARC system, improved scheme is proposed basing on the existing LANDMARC location systems. On the basis of the existing laboratory equipment, a RF location system working at2.45GHz was designed and implemented. The main tasks are:(1) Overall system design:Selection of hardware equipment and achievement of location algorithm.(2) System hardware design: design of reader and tag:selection of MCU and RF communication module; design of system schematic and layout of PCB.(3) System Software design:The communication format of reader and tag were defined based on ISO18000-6communication protocol and completed the communication and location algorithm.Third, based on the comparison and analysis of a variety of indoor wireless location algorithm. The mean value model was used to reduce the impact of random factors on the RSSI for improving accuracy. The system was tested and verified. Mean while, the location accuracy, coverage and power consumption of the system were all tested.