Modeling Tidal Fading with the Two-Ray Model for Short-Range WiFi Overwater Communication

This research evaluates the two-ray propagation model as a tool for predicting tidal fading over short-range overwater WiFi links. We compare the accuracy of the i) full version of the two-ray model, which considers a material (e.g., relative permittivity) and polarization-dependent reflection coefficient, against the ii) simplified —yet widespread— two-ray model with a reflection coefficient magnitude of one. The evaluation is done resorting to a real-world dataset of a Shore-to-Shore (S2S) WiFi communication link operating in the 2.4 GHz band over an intertidal zone during an ebb period of about 2.5 h. The results show a clear agreement between received signal strength measurements and the full two-ray model, achieving a root mean square error below 1 dB. Overall, the work stresses the importance of using the complete two-ray model incorporating relative permittivity and antenna polarization in overwater communication modeling.