Analysis of Propagation Effects in Mobile Satellite Communications

Abstract

Mobile satellite communication systems that operate in the Ku-band (11-14 GHz band) and higher frequencies play a significant role in military and civilian communication systems. The satellites of interest are located in the crowded geostationary orbit with a 2 degree separation between adjacent satellites. This close spacing between adjacent satellites may lead to interference effects and, in order to limit interference to adjacent satellites, regulatory agencies have established strict limits on the effective isotropic radiated power (EIRP) from a particular terminal in its off-axis direction. Rugged terrain conditions are commonly encountered in mobile communications applications. In such terrains, the frequent motion of the antenna platform may lead to motion induced antenna pointing errors, which can be characterized by a random variable. It will be shown that such errors will lead to random variations of the terminal's off-axis EIRP spectral density. Since there are strict limits on the off-axis EIRP spectral density it is necessary to quantify these random variation. In this paper we will present a technique to analyze the time-varying interference at the adjacent satellites due to the propagation of the signal from a mobile satellite terminal.