Design Of Indoor And Outdoor Seamless Positioning System Based On GNSS/UWB Heterogeneous Network Handoff

With the continuous construction of complex buildings in the city,people's demand for navigation and positioning is increasingly prominent in the indoor and outdoor integration area.In the outdoor area,GNSS can be used to obtain the positioning results conveniently and quickly.However,due to the occlusion of buildings,GNSS signal becomes weak and the service scope becomes smaller,so it is unable to provide stable positioning service continuously.At the same time,due to the cost of base station installation,many indoor positioning technologies with more mature and higher positioning accuracy can not provide users with continuous and stable positioning service outdoors location based service.This requires the navigation system to provide smooth and stable positioning service in the indoor and outdoor fusion area.Through analysis and comparison,the traditional seamless navigation systems have some problems,such as high computational complexity,less consideration of state parameters and so on.Therefore,this paper uses GNSS and UWB as the navigation network in outdoor and indoor respectively,and proposes an indoor and outdoor seamless navigation algorithm based on clustering method,which can provide stable positioning service in the fusion area.For the problem of network selection in indoor and outdoor seamless navigation,this paper proposes a network switching algorithm based on GNSS and UWB under path constraint(PCNH),normalizes the collected SNR,RSS and other related parameters,then selects three trajectory points as the clustering center in the mobile trajectory of the terminal for three different regional positioning scenarios of indoor,outdoor and fusion area.Under the constraint of path moving direction,the Euclidean distance from each track point to different clustering centers is calculated and clustered to the corresponding positioning scene,so as to complete the network switching of indoor and outdoor seamless navigation.The experimental results show that PCNH can not only effectively suppress ping-pong effect,but also improve the accuracy of network handoff.In the process of multi-source information fusion positioning using heterogeneous network in indoor and outdoor fusion area,the satellite pseudo range is far greater than the UWB ranging range,which leads to the problem of large positioning error.Therefore,a joint positioning method of heterogeneous network under trajectory constraint(PC-EUOM)is proposed.By analyzing the satellite ephemeris,the pseudo range of the reference station is differentiated,and the satellite pseudo range correction term is obtained The observation equation of GNSS/UWB heterogeneous system is constructed,and the position is finally solved by the least square method.The experimental results show that the algorithm is effective and practical compared with the location algorithm without error matching.