Impact des multitrajets sur les performances des systèmes de navigation par satellite : contribution à l'amélioration de la précision de localisation par modélisation bayésienne

Abstract : Most of the GNSS-based transport applications are employed in dense urban areas. One of the reasons of bad position accuracy in urban area is the obstacle's presence (building and trees). Many solutions are developed to decrease the multipath impact on accuracy and availability of GNSS systems. Integration of supplementary sensors into the localisation system is one of the solutions used to supply a lack of GNSS data. Such systems offer good accuracy but increase complexity and cost, which becomes inappropriate to equip a large fleet of vehicles.This thesis proposes an algorithmic approach to enhance the position accuracy in urban environment. The study is based on GNSS signals only and knowledge of the close reception environment with a 3D model of the navigation area.The method impacts the signal filtering step of the process. The filtering process is based on Sequential Monte Carlo methods called particle filter. As the position error in urban area is related to the satellite reception state (blocked, direct or reflected), information of the receiver environment is taken into account. A pseudorange error model is also proposed to fit satellite reception conditions. In a first work, the reception state of each satellite is assumed to be known. A Markov chain is defined for a known trajectory of the vehicle and is used to determine the successive reception states of each signal. Then, the states are estimated using a Dirichlet distribution
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Signal and Image processing. Ecole Centrale de Lille, 2009. French. <NNT : 2009ECLI0001>


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Donnay Fleury Nahimana. Impact des multitrajets sur les performances des systèmes de navigation par satellite : contribution à l'amélioration de la précision de localisation par modélisation bayésienne. Signal and Image processing. Ecole Centrale de Lille, 2009. French. <NNT : 2009ECLI0001>. <tel-00446552v2>

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