Xiangyun Meng Xuanli Wu Full-Space UAV Trajectory Design for STAR-RIS-Assisted Secure Ground-Air Communications. 376-388 2026 10 IEEE Trans. Green Commun. Netw. https://doi.org/10.1109/TGCN.2025.3581390 db/journals/tgcn/tgcn10.html#MengW26 streams/journals/tgcn