ADJACENT SATELLITE INTERFERENCE IN GLOBAL MOBILE SATELLITE COMMUNICATIONS

This paper introduces the specific influence of adjacent satellite interference (ASI) as a unique negative propagation consideration affecting all types of satellite networks including global mobile satellite communication (GMSC) systems, which particularly negatively affects geostationary Earth orbit (GEO) satellite constellations. Any satellite network including GMSC could potentially cause ASI effects to their fixed and mobile users. There are two types of ASI effects, namely uplink and downlink ASI, which are discussed and examined in this paper. Downlink ASI occurs when the mobile receiving antenna beamwidth is large enough to receive additional signal levels from adjacent GEO satellites. On the other hand, uplink ASI occurs when adjacent satellites receive and rebroadcast strong uplink signals from mobile Earth station (MES) antennas, often because the antennas are either too small or improperly pointed. Modern mobile satellite terminals use very small antennas mounted onboard ships, land vehicles (road and rail), and aircrafts, including mobile military platforms. In practice, these mobile satellite communication terminals and antennas need to be small to increase transportability and facilitate easy installation. Antennas of this dimension greatly limit the achievable link budgets of satellite networks. In addition, the pointing error and focus of such antennas often requires using efficient modulation and power spectral density reduction technology successfully to mitigate all ASI influences.