Joint Terminal-UAV Association and Power Allocation for Hybrid Satellite-UAV Relay Network With Rate Splitting Multiple Access

In this paper, we investigate a hybrid satellite-unmanned aerial vehicle (UAV) relay network (HSURN) with rate splitting multiple access (RSMA), where the terminal transmits a superposition of the common and private signals with different power levels, and the UAV operates in half-duplex decode-and-forward (DF) mode to assist communication between terminals and satellites. With the RSMA scheme, we investigate the joint optimization problem of terminal-UAV association (TUA) and power allocation (PA) of both the terminals and UAVs for the common and private signals under the constraint of limited resources to maximize the achievable sum rate. Given the non-convexity of the original problem, it is decoupled into two subproblems. The TUA subproblem is solved via deep Q-network (DQN). The PA subproblem is solved by successive convex approximation (SCA) and Lagrange dual approach. Afterward, an alternate iterative algorithm is developed by iteratively performing the outputs of two subproblems. Numerical results verify that compared with the traditional transmission schemes, our proposed RSMA scheme is more beneficial to information transmission. Compared with the existing algorithms, the proposed algorithm can achieve the flexible association between UAV and the serviced terminal by adjusting the splitting strategy of common and private signals in dynamic network environment.