Research On Indoor Wireless Positioning Method Based On Ranging Of TOA

With the rapid development of wireless communication technology and mobile Internet,the demand for location service is increasing.GPS(Global Position System)positioning System is mainly designed to realize the wireless navigation and positioning function.GPS is suitable for spacious outdoor space environment.GPS signal coverage of bad areas,such as indoor,urban buildings,tunnels,underground space,etc.,requires indoor wireless positioning to achieve precise positioning of mobile devices.The hardware carrier of indoor wireless location mostly exists in all kinds of handheld terminals.As an important branch of positioning technology,indoor positioning technology is a technology that uses the wireless sensor network and wireless terminal equipment in the indoor environment to locate the user's location.Among many indoor positioning technologies,the practical value of indoor three-dimensional positioning technology is more prominent than that of two-dimensional plane positioning.In actual indoor environment,indoor wireless positioning technology can also provide real-time geolocation information services to the greatest extent.Currently,the common indoor wireless positioning technology is Wifi,bluetooth,infrared,ultra-broadband,RFID,ZigBee,etc.The realization of positioning technology mainly relies on the base station,combined with the mobile terminal,and finally realizes the wireless positioning.However,due to the complex and special indoor environment,the indoor 3D positioning technology currently faces the following related problems:First,how to overcome the indoor environment under the non-line-of-sight(NLOS)propagation environment of TOA error caused by multipath propagation,so as to improve the accuracy of positioning;Second,how to move the traditional 2d planar positioning technology into three-dimensional space,and then provide three-dimensional positioning services so that user needs can be satisfied.For the above two problems,based on the existing indoor wireless positioning research,this paper studies and improves the positioning algorithm based on TOA wireless ranging and combines many simulation experiments to explore whether the algorithm is feasible or not.The paper specifically refers to the following contents:(1)The system structure of indoor positioning system,key technologies and difficulties in developing indoor positioning are studied.The commonly used wireless ranging technology and the localization algorithm was introduced;To provide theoretical basis for indoor positioning system.(2)In multipath propagation under the non-line-of-sight environment(NLOS),a suitable base station is selected for each positioning terminal,and a ranging model based on TOA is constructed to reduce the influence of errors due to propagation environment factors.(3)Under the non-line-of-sight environment,using COMSOL software to establish a real physical field simulation environment.The four selected base station coordinates are respectively taken as the center of the sphere,and the distance between the base station and the terminal is taken as the radius to form a three-dimensional sphere positioning model.And simulate the centroid positioning algorithm.Comparing with RSSI and conventional centroid positioning algorithm,based on the results,the improved algorithm achieves a significant improvement in accuracy and good adaptability to the environment.(4)Based on TOA ranging,the centroid location algorithm is improved.Taking into account the concept of information fusion,a CL method based on distance weighting and a topological relationship model for positioning sphere formation are used.Combined with the positioning,the simulation results show that the improved positioning algorithm further improves the accuracy of the terminal coordinates,and further increases the applicability of indoor three-dimensional positioning.