GNSS Autonomous Localization: NLOS Satellite Detection Based on 3-D Maps

One of the main drawbacks of global navigation satellite systems (GNSSs) in urban environments is that signals may arrive at the receiver antenna only in nonline-of-sight (NLOS) conditions, leading to biased pseudorange estimates when they are taken for granted by the receiver and, eventually, wrong positioning. This article presents a study on the benefits of using three-dimensional (3-D) maps of cities to decide whether the GNSS signal coming from each tracked satellite is reliable. Based on this principle, two different 3-D maps and two methodologies are presented and compared. The results show the benefits of this approach.