Effect of Turbulence Layer Height and Satellite Altitude on Tropospheric Scintillation on Ka-Band Earth–LEO Satellite Links

Abstract

Tropospheric scintillation on Earth-space paths greatly increases at low elevation angles and/or higher carrier frequencies, may impair low margin systems, and can interfere with the power control algorithms used to mitigate rain fading. The amplitude and spectral characteristics of tropospheric scintillation have been well studied for Earth-geostationary-Earth-orbit (Earth-GEO) links, which have fixed elevation angles and path lengths. However, little has previously been reported concerning tropospheric scintillation on Earth-low-Earth-orbit (Earth-LEO) links, which are distinguished by the rapid change of the elevation angle as the satellite passes from horizon to horizon. In such cases, both the length of the slant path to the turbulence layer and the velocity at which the slant path passes across the turbulence layer rapidly change as the satellite passes across the sky. This affects both the intensity of the scintillation process, which generally reaches its maximum value at low elevation angles and/or during periods of rain, and the corner frequency of the scintillation process, which generally reaches its maximum value at high elevation angles. In this paper, we use a geometric model of propagation through the turbulence layer during a LEO satellite pass in conjunction with Tatarskii's theory of propagation through turbulent media to show that the corner frequency of the scintillation process increases as 1) the orbital altitude decreases and 2) the height of the turbulence layer increases. We also discuss the implications of our results for the simulation of tropospheric scintillation on Earth-LEO links.