Aerial IRS-Aided UAV-NOMA Networks: Joint Resource Allocation and Deployment Optimization

To tackle the challenges of channel quality degradation due to obstacle blockage and the scarcity of spectrum resources in wireless communications, a novel communication framework assisted by aerial intelligent reflecting surfaces (IRS) carried by unmanned aerial vehicle (UAV) based on non-orthogonal multiple access (NOMA) schemes is proposed in this paper, referred to as IRS-UAV-NOMA. The UAV equipped with an IRS (i.e., IRS-UAV) serves as a relay node, assisting in reflecting the signals from the base station (BS) to the ground users (GUs). In this paper, we jointly optimize the phase shift of the IRS, the transmit power of the BS, and the deployment position of the IRS-UAV to maximize the communication rate of the system. An effective two-layer joint optimisation algorithm adopting semi-deterministic relaxation (SDR) technique, convex convex process (CCCP) method and grid search (GS) algorithm is proposed to solve this highly complex non-convex problem. Numerical results demonstrate that: 1) the IRS-UAV achieves significant superiority over no IRS is set in the scenario; 2) the applied NOMA scheme outperforms the orthogonal multiple access (OMA) scheme in terms of enhancing the communication rate; and 3) the proposed algorithm can effectively improve network performance compared to other benchmark scheme while satisfying the constraints well.