Constructive use of GNSS NLOS-multipath: Augmenting the navigation Kalman filter with a 3D model of the environment

In this paper, we introduce a GNSS positioning approach that uses constructively non-line-of-sight (NLOS) signals. A 3D model of the environment is used to predict the geometric paths of NLOS signals. More precisely, we propose a version of the extended Kalman filter augmented by a 3D model, referred to as 3D AEKF, for GNSS navigation in NLOS context. In the proposed approach, the measurement model traditionally based on the trilateration equations is constructed from the received paths estimated by the 3D model. The Jacobian of the measurement model is calculated through knowledge of the wall on which the reflection has occured. To use even less reliable measurements, a robust version of the 3D AEKF is also proposed. Simulations conducted in different realistic configurations allow the performance of the proposed method to be evaluated.