Research And Implementation Of Wifi Single-Station Indoor Positioning Technology

With the rapid popularization and development of mobile communication and Internet technologies,people's demand for location services is increasing.As applications such as fire rescue,smart security,and more rely on location information today,people are increasing their research efforts on indoor positioning technology.At the same time,with the popularity of Wi Fi networks,indoor positioning technology based on Wi Fi signals has also become one of the research hotspots.Most of the traditional indoor positioning technologies need to combine multiple Wi Fi Access Points(APs)to achieve accurate positioning,but due to the complex and changeable indoor environment,it is often difficult to use multiple APs for positioning,and the existing single AP positioning technologies often have certain defects.Aiming at this problem,this thesis conducts research on single-station indoor positioning system for Wi Fi based on Channel State Information(CSI),and tests and verifies the performance of the system under actual indoor environment.The research contents of this article are as follows:First,based on the Orthogonal Frequency Division Multiplexing(OFDM)signal,this thesis analyzes the feasibility of ranging and direction finding on the CSI carrier phase of the OFDM signal subcarriers extracted from commercial Wi Fi signals;Using software radio platform and IEEE 802.11 n protocol to deeply analyze various errors in CSI phase,and then build a theoretical model of phase error according to the effect of each error on the phase of CSI carrier;Finally,according to the characteristics of each phase error,the corresponding phase error elimination methods are designed..Aiming at the real-time problem of algorithm,in order to realize the rapid positioning of the target and solve the positioning problem on some insufficient computing resources such as low-power embedded platforms,this thesis proposes a matrix beam-based signal Angle of Arrival(AOA)and Time of Flight(TOF)fast estimation algorithm,not only achieves accurate estimation of AOA and TOF,but also has low algorithm complexity;through line-of-sight(LOS)path recognition algorithm,it recognizes extreme points of AOA and TOF in LOS environment.Finally,the AOA and TOF information of the signal is combined to realize the single-station indoor positioning system.Finally,this thesis builds a positioning system based on a software radio platform in an actual indoor environment,tests and performs performance verification,and analyzes the ranging accuracy,direction finding accuracy,and positioning accuracy in an indoor environment.The results show that the median error of the single-station indoor positioning system proposed in this thesis is within 1.5m,which meets the needs of high-precision indoor positioning.