ANALYSIS OF LEO, MEO, AND GEO GLOBAL MOBILE SATELLITE SYSTEMS IN THE PRESENCE OF INTERFERENCE AND FADING

Several multisatellite and multispot systems have been recently propos ed for provision of mobile and personal services with global coverage, adopting GEO or non-GEO (i.e., MEG, LEG) satellite constellations. Th e paper addresses an in-depth analysis of these constellations, evalua ting both geometrical performance measures and cochannel interference levels caused by extensive frequency reuse. The geometrical analysis y ields the statistics for coverage, frequency of satellite hand-overs, and link absence periods. The interference analysis is based on a gene ral model valid for all access techniques, which is here applied to th e case of FDMA. The outage probability as a function of the specificat ion on carrier-to-interference power ratio is evaluated for four selec ted constellations. Several techniques are introduced for interference reduction in non-GEO systems, in which the satellites coverage areas may intersect: spot turnoff, intraorbital plane frequency division, an d interorbital plane frequency division. The effects of Rice fading ha ve also been analyzed by means of an analytic approximated method. The overall analysis allows a fair comparison between LEG, MEG, and GEO c onstellations.