Research On Key Technologies Of Indoor Positioning Based On The Fifth Generation Mobile Communication Signal

With the development of the 5th Generation Mobile Communication Systems(5G)and the popularization of mobile terminals,positioning in various indoor environments such as shopping malls,hospitals,factories,and underground parking lots is becoming more and more common,and the accuracy requirements are getting higher and higher.Since 5G has the characteristics of lowlatency high-bandwidth communication and Massive antennas,it has attracted extensive attention from researchers.This paper mainly studies the key indoor positioning technologies based on 5G signal.First,this paper introduces the research background and the research status of indoor positioning.The main positioning methods include Wi Fi signal positioning,Ultra Wide Band(UWB)signal positioning and 5G signal positioning,etc.The advantages of 5G positioning are discussed,and the research content and significance of this thesis are introduced.Then,In the line-of-sight environment,based on 5G low-frequency band signal,a twodimensional high-precision indoor positioning method is proposed with one base station.The proposed scheme does not require the time synchronization between the base station and the user equipment,and can achieve centimeter-level indoor positioning accuracy when the signal-to-noise ratio is 12 d B,the signal bandwidth is 10 MHz,and the number of receive antennas is 24.Specifically,an improved angle-time joint estimation algorithm is investigated,and two positioning enhancement methods based on beamforming are proposed.The effects of factors such as the number of antennas,bandwidth and noise on the positioning accuracy are analyzed.Finally,by employing the millimeter wave signal,a three-dimensional high-precision indoor positioning method is proposed,which is based on a single base station and assisted by Reconfigurable Intelligent Surface(RIS).For the positioning assisted by one RIS,the Cramér-Rao bound of the positioning error is first analyzed,and guides the settings of the RIS element.The positioning method based on the Multiple Signal Classification(MUSIC)algorithm and subcarrier beamforming is proposed.On the other hand,assisted by multiple RISs,the user’s position is estimated according to the Time Difference of Arrival(TDOA)of the signal passing through different RISs.The simulation results show that under the optimized phase of the RIS elements,the theoretical positioning accuracy can be improved from centimeter level to millimeter level.