GNSS Ocean Bistatic Statistical Scattering in the Time-Varying Regime: Simulation and Model Validation

This work develops around the problem of modeling statistics and correlation properties of the Global Navigation Satellite System (GNSS) L-band signal scattered by the moving ocean surface, presented in the companion article by Principe et al. (2021). The modeling work is here completed by deriving an effective method for simulation of the received signal as well as by making a validation study based on simulated and real data. The simulation of the stochastic process embedding the design statistical properties, the temporal correlation model and the system and surface parameters is intricate, in general, and provides a useful tool for researchers interested in modeling and simulation of GNSS reflected signals from a time-evolving sea surface. The GNSS received waveforms after 1 ms coherent integration are simulated and the correlation properties of the specular and near-specular points are compared to the theoretical model and to results from real data. Real raw data were collected during an aircraft mission in the Gulf of Finland and in a spaceborne scenario with Cyclone Global Navigation Satellite System (CYGNSS) satellites. Comparisons show good agreement among simulations, model, and real data, and demonstrate that the estimated correlation time of the GNSS-R signal fits real data with higher accuracy with respect to the case in which sea correlation is not accounted, especially when the receiving platform velocity is moderate.