Research on fast satellite selection algorithm based on geometry

The positioning accuracy with Global Navigation Satellite System (GNSS) depends on both the pseudorange error and the geometric dilution of precision (GDOP), and GDOP is depended on the geometry of user/satellites which are selected. Positioning with a GNSS needs at least four satellites which are visible for the user so that at least four pseudorange measurements can be provided to determine the user position in three dimensions and the receiver clock offset. In order to select as few as visible satellites whose geometry is better, a new fast satellite selection algorithm based on geometry is come up with by this paper through analyzing geometry characteristics of the optimal visible satellites combination. The expected visible satellites are selected based on the distribution characteristics of elevation angles and azimuth angles combined with tetrahedron volume. Taking GPS, GLONASS and GALILEO system for examples, this paper compares the algorithm proposed by this paper with the best geometry satellite selection algorithm through simulation. The simulation results show that the algorithm proposed by this paper solves the problem that there are a lot of matrix multiplications and matrix inversions in the best geometry satellite selection algorithm. So the new algorithm can reduce computational complexity and increase receiver processing speed. The theory of the algorithm is simple and easy to use. Meanwhile, the algorithm can satisfy the real time requirements for users.