MIMO application for reduced adjacent satellite interference in SATCOM downlinks

Due to the steady increase of satellite networks in the geostationary arc, operators and governments must take measures to ensure that each network can operate without being interfered by adjacent satellite networks. Usually this is achieved by strict regulation of the allowed power spectral density within the shared operating spectrum. Unfortunately, limiting the allowed transmit power ceteris paribus manifests in limited data rates, especially if terminals with small apertures are used. In this paper we will show that the recently proposed Multiple Input-Multiple Output (MIMO) technology for communication satellite systems is a convenient concept to mitigate data rate limitations induced by adjacent satellite interference (ASI). Given a fixed data rate required by the end user, MIMO systems are superior over conventional Single Input - Single Output (SISO) systems because they work at less satellite transmit power and, therefore, enable more narrow satellite spacing or smaller ground terminal dish sizes without violating negotiated ASI limits.