Geometric Information-based Methods For Indoor Positioning Error Mitigation

With the development of information and communication technology,indoor applications are becoming more and more abundant.Based on applications such as production or management,the demand for location services is increasing day by day.At present,the outdoor positioning technology is mainly based on satellite GPS positioning.However,in the indoor environment,there is a problem that satellite signals cannot penetrate the building,and indoor positioning technology is needed as a supplement to satellite positioning.At present,several mainstream indoor positioning technologies include Bluetooth positioning,UWB positioning,WIFI positioning,and fusion positioning.According to many years of research on indoor positioning at home and abroad,it is found that the fusion positioning technology has the advantages of high accuracy and low power consumption.In recent years,the problem of fusion positioning based on TOA-AOA has received widespread attention.This method can use ranging information and angle measurement information for coordinate estimation,and can meet the positioning needs in the case of fewer base stations.Since the multipath signal in the indoor environment is still an important factor that interferes with the TOA-AOA joint positioning result,suppressing non-line-of-sight errors is an important issue in indoor positioning technology.The existing non-line-of-sight suppression methods have shortcomings such as high computational complexity and easy to fall into local optimal solutions.This paper proposes a non-line-of-sight suppression method based on geometric information,which mainly uses geometric algorithms to filter and delete non-line-of-sight information with large errors.Through experimental analysis,this method effectively improves the positioning accuracy.(1)First,in an environment with relatively simple indoor geometric conditions,an AOA error suppression algorithm based on CRLB weighting is proposed.The algorithm uses a pair of base station measurement information to estimate position coordinates,and assigns CRLB weights to each set of estimation results.The use of spatial smoothing algorithm to filter combinations improves the calculation speed and effectively suppresses the non-line-of-sight error of the AOA algorithm.This algorithm has good positioning accuracy.It is suitable for conditions with ideal geometric information.When the geometric relationship between the base station and the terminal is poor,the positioning accuracy is greatly reduced.Therefore,a positioning error suppression algorithm that requires geometric information is needed to eliminate errors.(2)Then,in the indoor environment with complex geometric conditions,the TOA-AOA joint positioning problem is studied.In the proposed geometric information-based positioning error suppression method,the uniform motion of the mobile terminal can be used to effectively eliminate TOA.Time synchronization error.The mobile terminal sends a signal to the base station and the base station receives the signal.The geometric relationship between the mobile terminal at time t,t+1 and the fixed base station is analyzed,and the geometric error suppression algorithm is used to calculate the threshold of measurement error to filter out Distance from the base station in the environment.The TOA-AOA joint equation is solved based on the two-step weighted least squares algorithm.The proposed algorithm can effectively suppress the influence of non-line-of-sight errors and measurement noise.(3)Finally,the positioning error suppression algorithm for geometric information is subjected to comparative experiments under different noises,different base station arrangements,and different terminal movement modes.Experiments have proved that the geometric information positioning error suppression algorithm can effectively suppress nonline-of-sight errors,and is stable in an environment with increased noise.It performs very well in a non-line-of-sight base station environment.The terminal can not only achieve continuous positioning,but also It can have good positioning performance under free movement.