Improved 2-Ray Model for Overwater Propagation Channels: Modeling the Instantaneous Variations in the Received Signal Strength

Based on analyzing two-day ship-to-shore propagation measurements performed simultaneously at two frequency bands (1.39 GHz and 4.5 GHz), we extract the small-scale fading (SSF) and show that the higher the frequency, the larger the amplitudes of the SSF. Consequently, we introduce a modification to the 2-ray model so that the behavior of the SSF at different frequency bands is captured. We model the effect of the randomness and the unknown dynamic details of the propagation environment as a zero-mean Gaussian random variable which is then superimposed on the length of the rays in the traditional 2-ray model. For the measured environment, it is found that a standard deviation in the sub-centimeter range is able to characterize these unknown details and almost replicate the behavior of the observed SSF at these two bands.