Study On Indoor And Outdoor Fusion Position Technology Based On Beidou And Ubiquitous Wireless Network

As people's demands for location-based service is increasing.Single indoor and outdoor positioning has been unable to satisfy the basic requirements of people,which makes the indoor positioning technology integration becomes a hot research topic in the location based service.At present,the Beidou wide area pseudo range differential satellite navigation positioning technology can achieve outdoor real-time precision positioning,Beidou position and indoor WiFi ubiquitous network position have been widely supported by mobile terminals and other devices,which making Beidou and WiFi fusion location become the mainstream technology of indoor and outdoor global position.Therefore,this thesis mainly studies the following research of the fusion positioning method based on the Beidou and WiFi.Firstly,the principles and characteristics of Beidou pseudo range difference and ubiquitous wireless network localization technology are analyzed.Typical Beidou differential technology is analyzed and compared.The typical Beidou differential technology,the main error sources,differential information broadcasting and correction methods of pseudo range difference are studied.A signal propagation model of indoor complex environment with NLOS and Gauss noise is established,and the HUAWEI indoor path loss model is modified to make it fitter for the actual position signal propagation characteristics.The Chan algorithm is used to estimate the initial position as the initial value of the Taylor series algorithm to solve the position problem,which can solve the position divergence caused by inaccuracy of initial value.The simulation experiment shows that the algorithm can effectively improve the positioning accuracy and efficiency.Secondly,in order to reduce the distance error of the mobile terminal,the pseudo range differential positioning based on multiple reference station is proposed.According to the terminal and the base station distance,the terminal integrated pseudo range correction number is interpolated by the inverse distance weighting method.Aiming at the influence of receiver error,as the main error source of the pseudo range observation error,the receiver clock error of the reference station is improved,which achieves the effect of reducing the receiver clock error on the position result.The simulation experiment shows that the method can improve the positioning accuracy effectively.Thirdly,in order to make full use of the Beidou and WiFi signals to improve the positioning accuracy and achieve indoor and outdoor seamless position,an indoor and outdoor position algorithm based on the fusion of Beidou and WiFi is proposed.Aiming at Beidou and WiFi fusion positioning mode,how to choose the beacons and constellations involved in position and determine the number of participants in position,and put forward a decision rule based on average and cost function.The first mobile terminal for signal acquisition cycle scan the surrounding environment,and the normalized value of the cost function and descending order,the selected value is less than the average value of the cost function of the beacon or sign in positioning cost function,and select the weight coefficient of each parameter in the cost function is verified by.The simulation experiment shows that the position accuracy and robustness of the algorithm are better than that of the single position.Finally,This thesis studies the switching mechanism of mobile terminals in the heterogeneous network environment,a handoff decision algorithm based on mobile terminal stable cycle assessment is proposed to ensure seamless handover of mobile terminals.The algorithm combines the state of mobile terminal to improve the cost function,and the stability period evaluation decision algorithm is introduced to solve the table tennis handoff effect.The simulation experiment shows that the algorithm realizes the seamless handoff between the Beidou and WiFi heterogeneous networks,and reaches the smooth transition of the indoor position switching.