Research On The Indoor High Accuracy 3-D Positioning Technology And Algorithm Based On TOA

In modern life,human activities and living areas are increasingly concentrated in the indoor environment,which leads to an urgent demand in indoor positioning with complicated and mutable channel conditions.Indoor positioning technology has turned into a very challenging research direction in the current wireless communication field.Supported by WIFI technology,this thesis realizes indoor high accuracy 3-D localization based on TOA ranging primarily through the research of three positioning-related aspects such as physical ranging,position calculating,position correcting and so on.The main efforts done in this paper are as follows:In the aspect of physical ranging,the paper introduces several commonly used localization methods,and focuses on the positioning method based on TOA.The realistic feasibility of TOA positioning is analyzed in the first place from the perspective of improving the clock resolution and eliminating the clock synchronization error.Specifically,aiming at the TOA ranging error caused by environmental factors such as multipath and NLOS propagation in indoor wireless channel,the ranging error correction algorithm based on a prior error model is proposed,which can make the ranging error reduced by 64% so as to improve the location precision.For position calculating,considering the multi-story indoor positioning environment,we propose a step-by-step localization algorithm combing floor determining and plane positioning to obtain the spatial position information of the MT.To begin with,the paper analyzes the relationship between the height position and the positioning demand.It is indicated that the accuracy of the floor information should be given priority over the accuracy of the height position in multi-story buildings.Under this special requirement,the center of the circle formed by the intersection of the two TOA spheres can be used in conjunction with the relevant criteria to determine the floor position of the MT.Besides,the floor number which acquired by floor determining will be transformed into a specific height value by means of forecasting,and then the 3-D positioning of the MT is simplified to plane positioning.Finally,the position coordinates of the MT in the current floor can be calculated through an improved weighted centroid algorithm later.The experimental results show that the proposed 3-D localization algorithm can achieve higher accuracy than 95% for the floor determining and control the average plane positioning error within 1.3m.The correction of the localization results is also an important part of the indoor positioning.First,the paper puts forward the concept of location area accuracy in order to meet the actual demands of location-based service.Through analysis the preferred research direction of indoor position correcting—improving the location precision based on the accuracy of the MT's location area is obtained.Second,the indoor map information is used throughout the correction process and it is required to be divided into three categories according to the needs of the positioning results correction.Third,the location area decision mechanism based on the map partition is proposed depended on the motion law of the MT in the interior space.In this mechanism,the accuracy of the MT's location area is judged and verified by means of threshold analysis or weight comparison.Meanwhile,the MT's positioning track is smoothed by using the relevance among the positioning results in different location areas.Thus,the fixed-interval track smoothing(FITS)algorithm and the variable-interval track smoothing(VITS)algorithm based on the location area decision are formed,which can fully ensure the accuracy of the MT's location area and make the average location error less than 0.9m.