Beam Splash Mitigation for NGSO Spectrum Coexistence between Feeder and User Downlink

Non-geostationary (NGSO) satellite systems face a significant number of technical challenges when compared to conventional GSO systems, the most critical being the satellite mobility. The time-varying projection of the satellite spot-beam over the target area, i.e. the beam splash, may overlap with neighboring beams and result in inter-beam interference when those beam share the same spectrum. Given the large number of gateways needed to feed a NGSO constellation, and the common requirement of satellite customers to have gateway close to the end-users, it is expected to have beam splash effect between feeder and user downlinks. The main goal of this paper is to shed light on this rather unexplored coexistence scenario by providing link budget analysis and proposing beam-nulling solutions to mitigate the potential risk of interference.