A polarimetric line-of-sight channel model for MIMO satellite communications

Spatial multiple-input multiple-output (MIMO) offers increased rate and/or reliability in rich scattering environments such as that of a multipath non-line-of-sight (NLOS) channel. In line-of-sight (LOS) dominated conditions, spatial diversity is reduced. Dual polarisation signalling has been shown to successfully exploit polarisation diversity when LOS is dominant. For satellite systems, such state-of-the-art dual-polarisation techniques do not currently account for the 3D geometry of the link, and specifically the polarisation mismatch from misalignment of the antenna elements. Performance loss due to the mismatch in antenna orientation can be overcome by using 3D polarimetric antennas at both the transmitter and receiver. In this paper, we present a novel polarimetric LOS MIMO channel model by combining satellite geometry, the Friis equation and polarisation mismatch. Our emphasis is on polarisation mismatch and how this varies over the field-of-view (FOV). Our model offers the opportunity for 3D polarimetric signalling techniques to deliver enhanced and more consistent link performance over the FOV.