| In recent years,with the continuous increase of smart terminals and the development of wireless LAN technique,the demand for location-based service is getting wider and wider,which requires the accuracy of indoor positioning more and more accuratly.However,due to unstability of the Wi Fi receiving module of the smart terminal or inaccessibility of the signal from the access point,the smart terminal can not receive the Wi Fi signal for a period so that it can not peform indoor location.For those applications such as underground coal mine,it will increase the risk.In order to improve the accuracy of indoor locating,in this thesis the Wi Fi technique,map matching technique and the trajectory prediction technique are combined to apply for the indoor positioning.The main work of this thesis is as follows:1.The Wi Fi signal strength-based indoor locating algorithm is combined with the map matching fusion.The algorithm combines Wi Fi location and map matching algorithm.Acording to the signal strength of Wi Fi,it calculates the user location,which is combined with the information from the electronic map on the server.The map matching algorithm can correct the mistake and get a closer coordinate of the user's real location.This fusion algorithm might reduce the hardware cost and improve the accuracy of indoor locating.2.The trajectory prediction technique is studied for the indoor locating.By analyzing and comparing the trajectory prediction method based on the probability statistics and Markov chain,the second-order Markov chain-based trajectory prediction is applied to the indoor locating.As the locating accuracy directly affects the prediction accuracy,the prediction accuracy is higher with the higher locating accuracy.In this thesis,a combination of the trajectory prediction technique,Wi Fi signal strength and the map matching is defined for indoor locating,which not only provides the user location,but also reduces unnecessary risks. |
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