Beamforming and Power Allocation in NOMA-Based Multibeam Satellite Systems with Outage Constraint

In this paper, we propose a joint beamforming (BF) and power allocation scheme for non-orthogonal multiple access based multibeam satellite systems. Unlike the existing works where perfect channel state information (CSI) is required, we use imperfect CSI in formulating a constrained optimization problem aiming to minimize the maximum individual antenna powers subject to the outage constraints of quality-of-service requirements. Since the original problem is mathematically intractable, we first adopt Bernstein-Type II inequality to convert the outage constraints into deterministic forms. Then, an alternating optimization algorithm is proposed to jointly design BF vectors and power allocation coefficients. Finally, simulation results are provided to demonstrate the robustness and superiority of the proposed scheme compared with benchmark schemes.