Map-Aided GNSS Positioning

The increasing urbanization poses challenges for reliable Global Navigation Satellite System (GNSS) positioning in urban canyons, where high-rise buildings often lead to poor positioning performance. The obstruction and reflection of GNSS signals by building surfaces, known as non-line-of-sight reception, add extra travel distance to ranging measurements and degrade accuracy. Smart city development has accelerated the creation of open-source 3D building models, opening new possibilities for GNSS positioning in urban areas. 3D building models provide information on obstacle size and location, aiding in predicting signal blockage and reflection. GNSS algorithms have been developed to identify and correct blocked signals, turning them into positioning features, categorized as 3D mapping-aided (3DMA) GNSS. This largely advanced urban positioning, with popular algorithms like shadow matching and ray-tracing GNSS widely adopted in low-cost receivers and commercial applications. This chapter goes through the evolution of 3DMA GNSS, detailing existing algorithms, and introducing advanced positioning techniques. The discussion concludes by addressing the limitations of 3DMA GNSS.