Evaluation of Geopositioning Using Frequency Responses From Radio Propagation Measurements

Abstract: Satellite reliant navigation systems may struggle in urban environments as tall buildings mayobstruct necessary direct lines of sight with satellites. There have been multiple studiesexamining how WIFI fingerprinting may be used for indoor positioning. This project aimed toinvestigate the feasibility of applying similar techniques for outdoor positioning as analternative to satellite navigation. Wide band radio propagation measurements between three different base stations and avehicle have been recorded in Kista, Stockholm. From the measurements the signal powercould be found along with the Power Delay Profile. The discernible information from themeasurements were then used to design a K-D Tree which was used in order to perform a KNearest Neighbour search. The K Nearest Neighbours could then be used in a regressionmodel to estimate the position. Tests were designed and performed in order to evaluate theestimation error as parameters such as amount of training data and number of neighbourswere varied. The results showed that positioning using received frequency responses from three separatebase stations was possible. The best result obtained showed an estimation error of less than14,3 meters within a 95th percentile confidence interval. However, further research isneeded to investigate the robustness and reliability of the system in more dynamicalenvironments.