Research On ISAC Localization Technology Based On OFDM Radar Imaging And Map Matching

From the second generation mobile communication to the sixth generation mobile communication(6G),localization is an increasingly important module.In the field of mobile communication,the application scenarios of positioning technology include indoor and outdoor mobile device localization and navigation,emergency rescue,crowd detection,smart city traffic management,automated factories,etc.In traditional mobile communication,by measuring the received signal strength,time of arrival(TOA),time difference of arrival(TDOA),angle of arrival(AOA)and other information between the equipment and its surrounding at least two base stations,these Information are mapped to the mathematical model representing the geometric position relationship,so as to solve the position information and achieve positioning.The more accurately the distance and angle are estimated,the higher the positioning accuracy will be.The ideal situation for realizing positioning is that the communication channels between devices and surrounding base stations have a line-of-sight path.However,the real propagation environment is very complex,and signals may experience obstruction,fading,as well as multipath effects such as reflection and diffraction during the propagation process,resulting in the absence of a line of sight path.As the fifth generation mobile communication(5G)and 6G move towards the millimeter wave and terahertz frequency bands,the higher the frequency,the weaker the diffraction and penetration capabilities of the signal.Accurate positioning of millimeter wave systems under non line of sight paths is a relatively difficult problem to solve.The Integrated Sensing and Communication(ISAC)technology has been widely recognized as a new reciprocal solution for communication and radars,mainly aimed at solving spectrum congestion,signal interference,and other issues caused by the continuous proximity of communication frequency bands to radar frequency bands.This system allows communication and radar sensing to share resources such as spectrum,waveform,signaling,hardware,protocols,and networks,enabling communication and sensing functions to collaborate and promote each other,improving overall performance,and cultivating more promising applications.The deployment of radar sensing function in mobile communication systems has inspired a new way to achieve precise positioning of millimeter waves in non line of sight paths,and this article conducts in-depth research on this.The main research work and innovations of this article are as follows:1)A study was conducted on the positioning technology based on orthogonal frequency division multiplexing(OFDM)radar mapping and maps matching.Firstly,an ISAC mapping technology based on OFDM signals was proposed.Based on the obtained maps,a localization method based on map common scatterers matching was further proposed,and corresponding simulation verification was conducted.Unlike traditional positioning techniques that rely on line of sight paths,the biggest advantage of this positioning method is that it does not rely on the line of sight paths between devices during positioning.2)A study was conducted on the ISAC localization method based on modern image recognition and feature points matching.Based on the open map dataset that utilizes OFDM millimeter wave radar to map the real environment,we innovatively utilize the mainstream Scale Invariant Feature Transform(SIFT)algorithm in image recognition and matching technology for map recognition and matching,further verifying the feasibility of the proposed maps matching based localization technology in practical scenarios.The experimental data shows that its positioning accuracy is consistent with the simulation results in Chapter 3 of this article.