NOMA Assisted Semi-Grant-Free Transmission Scheme in Satellite Systems

This letter investigates the uplink semi-grant-free (SGF) transmission in satellite communication systems. Specifically, based on the available statistical channel state information, we first propose a non-orthogonal multiple access assisted SGF scheme, which enables many multi-antenna mobile terminals and one earth station to access the satellite network within the same resource block. Then, by assuming that the satellite channels undergo shadow-Rician distribution, we derive the closed-form throughput expression of the considered system, where the effect of imperfect successive interference cancelation is taken into account. Finally, simulation results validate the effectiveness of the theoretical analysis and the superiority of our proposed scheme. Besides, the influence of typical parameters on the system performance is also revealed.