Optimum-Capacity MIMO Satellite Broadcast System: Conceptual Design for LOS Channels

In line-of-sight (LOS) radio channels maximum multiple input multiple output (MIMO) channel capacity is obtained if an orthogonal MIMO channel transfer matrix is available. For the special case of the MIMO satellite channel, we will analytically derive a design prescript that allows for the construction of orthogonal channel matrices via the explicit positioning of two satellite antennas in the geostationary orbit. Simultaneously, a particular arrangement of an arbitrary number of ground station antennas placed on earth is assumed. In a computer simulation this conceptual design rule is illustrated and verified with a satellite communication link consisting of both a MIMO uplink channel and a MIMO downlink channel. The uplink is established between two anchor stations and a satellite system, also equipped with two antenna elements. In downlink direction the information is transferred from the two-antenna satellite system to a mobile receiver with an arbitrary number of antenna elements. The MIMO capacity optimization strategy is shown to exceed at least 90% of its theoretical maximum in all cases, nearly doubling the data rate compared to ordinary two- satellite MIMO systems, which are currently found in literature.