Fading Channel Models for the Assessment of GNSS Receivers

Applications based on global navigation satellite system (GNSS) positioning for difficult environments, such as indoor, the urban canyon or low Earth orbiting satellites, have become very attractive in recent years. For a rigorous assessment of receiver performances in controlled laboratory conditions with respect to their objective environment, a precise knowledge of the electromagnetic radio channel is required. Different propagation mechanisms (diffraction, reflection and scattering) are combined together originating signal variations that affect receiver performance. Shadowing and blockage due to obstacles, frequency selective fading due to multipath, large building penetration losses or strong fading due to ionospheric scintillation are some examples of the impairments that GNSS receivers may encounter. In this paper, fading channel models that generate time-series are analysed for establishing procedures to assess the performance of GNSS receivers in different environments by, first setting error bounds in software implementations, and later, using RF signal simulators.