SIMULATION OF RAIN FADING AND SCINTILLATION ON Ka-BAND EARTH-LEO SATELLITE LINKS

In the near future, many of the research, communications relay and Earth observation satellites that will be placed into low Earth orbit (LEO) will use high speed Ka-band links to communicate with Earth stations during the short time they pass over a given location. The motion of a LEO satellite across the sky will cause the Earth-space path to pass through any rain cells and turbulence cells in the vicinity very quickly leading to steeper fade slopes and more rapid scintillation than in the well-studied geostationary case. Until extensive measurement programs are undertaken, simulation based upon reasonable models of the atmosphere is the likely best option for assessing the severity of fading on such links. If the spatial statistics and/or distributions of the rain and turbulence cells are known, one can predict the rate at which rain fading and scintillation will occur. We have used this insight to construct a channel simulator that can provide plausible predictions of the instantaneous path loss on Earth-LEO links during a given pass.