From the point of view of Intelligent Transportation Systems (ITS) safety applications, accurate and reliable positioning system for road users is the most important part. Although GPSs (Global Positioning Systems) are the most widely utilized technology today, they still have the problems of performance degradation caused by multipath propagation in urban canyons. Many approaches have been employed to eliminate multipath signals in order to reduce positioning errors. Among these, those that consider the geometry of surrounding buildings to improve the evaluation of possible multipath signals have gained most interest. This study proposes an approach to estimate position by searching around the result of GPS. The proposed algorithm evaluates the pseudoranges of the possible multipath signals by referring to the building geometry. The assumed position is estimated by using received pseudoranges and is evaluated by the likelihood of the possible positioning error and filtering algorithm. The proposed method was verified through field experiments in urban canyons in Tokyo.
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