Research On LOS/NLOS Ranging And Positioning Method Based On UWB

In recent years,with the development of wireless communication technology and wireless sensor network,it has become a hot research topic to realize high precision positioning indoor.The traditional positioning technology is difficult to overcome the interference of indoor environmental factors and meet the user high precision,low cost and low complexity requirements at the same time.Ultra-wide band(UWB)wireless communication technology has the advantages of low transmission power,strong multi-path resolving ability and strong penetrating ability.UWB has a very wide application prospect in high precision positioning under complex indoor environment.In this paper,the characteristics of the UWB positioning technology in the indoor line of sight/not line of sight(LOS/NLOS)are studied.The method of high precision ranging and positioning under LOS/NLOS is proposed.Indoor positioning platform is set up.Firstly,this paper briefly analyzes the advantages of UWB positioning technology compared with traditional positioning technology in positioning accuracy,positioning range and power consumption.By studying the characteristics of UWB Gaussian pulse in time domain and frequency domain,the influence of Gaussian pulse order and shape factor on UWB Gaussian pulse is analyzed theoretically.The optimal Gaussian pulse order is 5 and the forming factor is 0.4ns.Secondly,by analyzing the error of the indoor range algorithm,it is concluded that the precision of the SDS-TWR algorithm based on TOA is high,and the implementation process and the key code have been written.The high precision ranging platform of the SDS-TWR algorithm based on TOA under the optimum conditions was obtained by modifying the distance measurement of UWB pulse repetition rate,UWB signal center frequency and bandwidth and other ranging factors.Its ranging accuracy can reach 8cm.Thirdly,after analyzing the NLOS experimental results of metal,wood and plastic,the LOS/NLOS identification method of path loss model is proposed.The mathematical model of material coefficient is established,which is used to identify obstacle's material.The error can be compensated according to the error curve fitted by different obstacles.Fourth,a parameter estimation method of path loss model is proposed,which provides an effective method for the fixed blind nodes and the path loss model parameters in NLOS environment.Finally,both high-precision ranging platform of the SDS-TWR algorithm based on TOA and the weighted centroid algorithm based on the intersection of the trilateral positioning algorithm are used to complete the indoor high-precision wireless sensor network positioning system.The accuracy measured under indoor experiment is 15 cm.