Stationary, Cyclostationary and Nonstationary Analysis of GNSS Signal Propagation Channel

In this paper, the characteristics of received Global Navigation Satellite System (GNSS) signal amplitudes are analyzed under different scenarios including urban, semi-urban, foliage and indoor environments. Stationary, cyclostationary and nonstationary analyses are used to characterize the variations of the received signal amplitude under the aforementioned scenarios and various propagation models are validated using live GPS data. Both static and dynamic conditions are considered. Signal amplitude variations are highly dependent on the number of reflectors, receiving antenna gain pattern, user dynamics, characteristics of the signal blocking elements and time between blockages. In this paper, the dependence of the signal amplitude on the mentioned factors is empirically investigated using real GPS signals. It is shown that under certain scenarios, variations in the amplitude time series can be modeled as the linear combination of a few sinusoids. The amplitude variations become less predictable even in the presence of small user dynamics.