  This paper proposes a cognitive radio enabled LEO SatCom using RSMA radio
access technique with the coexistence of GEO SatCom network. In particular,
this work aims to maximize the sum rate of LEO SatCom by simultaneously
optimizing the power budget over different beams, RSMA power allocation for
users over each beam, and subcarrier user assignment while restricting the
interference temperature to GEO SatCom. The problem of sum rate maximization is
formulated as non-convex, where the global optimal solution is challenging to
obtain. Thus, an efficient solution can be obtained in three steps: first we
employ a successive convex approximation technique to reduce the complexity and
make the problem more tractable. Second, for any given resource block user
assignment, we adopt KKT conditions to calculate the transmit power over
different beams and RSMA power allocation of users over each beam. Third, using
the allocated power, we design an efficient algorithm based on the greedy
approach for resource block user assignment. Numerical results demonstrate the
benefits of the proposed optimization scheme compared to the benchmark schemes.
