Feasibility of Using Beam Steering to Mitigate Ku-Band LEO-to-GEO Interference

Low-Earth orbiting (LEO) satellites now hold promise to provide broadband service anywhere in the world, but they must share the radio spectrum with geosynchronous Earth-orbiting (GEO) satellites. The United Nations International Telecommunications Union (ITU) and the U.S. Federal Communications Commission (FCC) require that operators of LEO satellite systems avoid interfering with GEO satellite systems even though both use the same bands within the radio spectrum. Such interference can occur when a LEO satellite passes through an area between a GEO earth station and its intended GEO satellite. This is called an in-line event. In this paper we develop a first order estimate of the probability of occurrence of such an event, an indication that Ku-band LEO-to-GEO interference is a serious problem. We describe the use of beam steering to mitigate such interference and consider its feasibility for currently deployed LEO constellations. We find that beam steering appears to be a practical and effective approach for a LEO constellation that has this capability and uses sufficiently narrow beams.