Passive Channel Orthogonality Measurement Technique for MIMO SATCOM

Satellite Communication (SATCOM) links using geostationary satellites rely heavily on the line-of-sight (LOS) path to achieve a healthy link budget. Despite the LOS nature of the channel, recent research in the application of Multiple Input Multiple Output (MIMO) techniques in SATCOM have shown that an increase in channel capacity can be obtained using multiple antennas and satellites. In this paper we present a novel passive measurement technique to validate the orthogonality of a MIMO SATCOM channel matrix. The measurement method utilises existing downlinks from two satellites that have overlapping frequency coverage and beam footprints. Differential phase measurements are obtained using cross correlation analysis. These phase measurements are subsequently used to estimate the orthogonality of the MIMO SATCOM channel. Accuracy analysis of the technique plus simulated and measured results, are presented and discussed in this paper.