On Optimal Power Control for Cognitive Satellite-Terrestrial Systems

In the next generation of terrestrial systems (e.g., 6th generation (6G)), the Ku- and Ka-bands are expected to be utilized, much like their usage in low Earth orbit (LEO) satellite communications (SATCOM). Consequently, cognitive LEO-terrestrial systems have emerged as a key focus of recent advancements to address the spectrum scarcity problem in future wireless communications. This letter focuses on power control for cognitive LEO-terrestrial systems. Specifically, we study an optimal power control scheme for LEO ground users (GUs) to maximize the LEO system throughput while limiting the harmful interference to terrestrial base stations (BSs). Unlike previous literature that studied this problem in a sub-optimal manner, our work provides an optimal solution while considering more realistic channel models. Numerical results demonstrate the performance disparities between our optimal scheme and the existing sub-optimal scheme.