Distributed Digital Beamforming Techniques in Satellite Networks

In recent years, satellite communication systems, in particular LEO constellations, have been subject of increased attention in the new space race; this is substantiated by the numerous industrial endeavors aiming at providing high-speed broadband access anywhere at anytime, E.G., SpaceX Starlink. In 5G systems, there has been an increased focus to integrate a non-terrestrial component into the broader wireless communication infrastructure. It is expected that this trend will continue in the future. Satellites can provide coverage in areas where a terrestrial infrastructure is congested or unavailable; however, their energy resources are limited and due to the sidelobes in the multiple beam coverage, co-channel interference arises. Here, beamforming is an effective remedy for both problems. In this thesis, a distributed beamforming solution is investigated and compared with classic centralized methods. The distributed solution benefits from the fact that beamforming is not performed in a centralized manner in a single satellite, but is done collectively. So, if one satellite malfunctions, others can still provide coverage. Lastly, numerical simulations performed in MATLAB substantiate the advantages of distributed beamforming approach.