SC-Aided Spectrum Sharing Transmission in LEO Constellation Communication Systems

Low Earth orbit (LEO) satellite communication (SATCOM) systems have advantages of low transmission delay and insignificant signal pathloss, which make it as an ideal solution for the long distance non-line of sight communication. As another character of the LEO SATCOM, ground users could be covered by multiple satellite nodes. In this paper, we study multiple nodes multiple users downlink transmission methods for the LEO overlapping area. Recognizing there exists a satellite beam gain difference for beam-center and beam-edge users, a spectrum sharing based transmission method with selection combining strategy is proposed. Thanks to the feature of multiple coverage, beam-edge users are able to choose the strongest satellite node. To give insights of the method, the expression of outage probability is further derived. Simulation results show that the outage probability performance can be improved by using the new method.