Relay Selection and Power Allocation for Energy Efficiency Maximization in Hybrid Satellite-UAV Networks With CoMP-NOMA Transmission

Non-orthogonal multiple access (NOMA) and coordinated multi-point (CoMP) are two fundamental techniques considered for the fifth generation (5 G) of wireless communications. In this paper, a hybrid satellite-unmanned aerial vehicle (UAV) relay network (HSURN) is proposed where UAV relays (URs) employ CoMP transmission to serve terrestrial users (UEs). Furthermore, all UEs associated with CoMP-URs form single NOMA cluster. For model, an optimization problem formulated subject minimum quality services (QoSs) requirements UEs, power budgets and, successive interference cancellation (SIC), select URs allocate their powers energy efficiency (EE) maximization. With insight, first, computationally efficient sub-optimal UR selection scheme proposed. Then, allocated selected via Lagrange multipliers (LMO) method. Due non-convex nature problem, it relatively difficult be solved. Hence, metaheuristic teaching-learning-based (TLBO) algorithm employed achieve solution. Simulation results provided verify effectiveness TLBO-based allocation method compared LMO conventional Besides, obtained also reveal that CoMP-NOMA in scenario significantly improves spectral (SE) outage probability (OP) system non-comp case.