Characterisation of current and future GNSS performance in urban canyons using a high quality 3-D urban model of Melbourne, Australia

Abstract

Global Navigation Satellite System (GNSS) is a critical space-borne geospatial infrastructure providing essential positioning supports to a range of location-sensitive applications. GNSS is currently dominated by the US Global Positioning System (GPS) constellation. The next generation GNSS is expected to offer more satellites, better positioning provision, and improved availability and continuity of navigation support. However, GNSS performance in 3-D urban environments is problematic because GNSS signals are either completely blocked or severely degraded by high-rising geographic features like buildings. The aim of this study is to gain an in-depth understanding of the changing spatial patterns of GNSS performance, measured by the number of visible satellites (NVS) and position dilution-of-precision (PDOP), in the urban canyons of Melbourne, Australia. The methodology used includes the following steps: (1) determination of the dynamic orbital positions of current and future GNSS satellites; (2) development of a 3-D urban model of high geometric quality for Melbourne Central Business District (CBD); (3) evaluation of GNSS performance for every specified location in the urban canyons; and (4) visualisation and characterisation of the dynamic spatial patterns of GNSS performances in the urban canyons. As expected, the study shows that the integration of the GPS and Galileo constellations results in higher availability and stronger geometry, leading to significant improvement of GNSS performance in urban canyons of Melbourne CBD. Some conclusions are drawn and further research currently undertaken is also outlined.