Joint Power and Tilt Control in Satellite Constellation for NGSO-GSO Interference Mitigation

The number of non-geostationary orbit (NGSO) satellite constellations is growing persistently. Accordingly, co-channel interference with geostationary orbit (GSO) networks will inevitably affect the operation of NGSO and GSO satellites in the years to come. Towards protecting the well-established GSO systems from the interference produced by the newly launched NGSO satellite constellations, the international telecommunication union (ITU) has established regulations and evaluation metrics for the aggregated emitted power flux-densities from NGSO systems. In conformity with these regulations, the NGSO operators should avoid disruptive emissions, which could lead to acute service interruptions. To reduce the downlink interference levels and alleviate harmful service disconnectivity of satellite constellations, we propose a joint power and tilt control strategy to maximize user demand satisfaction. Our proposed method ensures that the equivalent power flux-density (EPFD) from satellite constellation satisfies the ITU regulatory limits while the radio resource management for the user service is optimized via power control and tilting. Simulation results analyzing EPFD levels and geographical dependencies and the performance of optimized LEO transmissions are presented, showing the benefit of the proposed technique in terms of service continuity and spectrum coexistence.