In space-air-ground integrated networks (SAGIN), terminals face interference from various sources such as satellites and terrestrial transmitters. However, managing interference with traditional interference management schemes (IM) is challenging since different terminals have different channel state information (CSI). This paper introduces a UAV carrying an active RIS (UAV-RIS) to assist in the interference elimination process. Furthermore, a UAV-RIS-aided IM scheme is proposed, which takes into account the multiple types of CSIs present in SAGIN. In this scheme, the satellite, terrestrial transmitters, and UAV-RIS collaborate to design precoding matrices based on the specific type of CSI of each node. Additionally, the DoF gain obtained by the proposed IM scheme is thoroughly discussed for SAGIN configurations with different numbers of users and transceiver antennas. Simulation results demonstrate that the proposed IM scheme outperforms existing IM schemes without UAV-RIS for the same type of CSI. The results also showcase the capacity improvement of the network when the proposed IM scheme is adopted under different types of CSI.

翻译：在空天地一体化网络（SAGIN）中，终端面临来自卫星和地面发射机等多种信源的干扰。然而，由于不同终端具有不同的信道状态信息（CSI），传统干扰管理方案（IM）难以有效处理此类干扰。本文引入了一种携带主动RIS的无人机（UAV-RIS）来辅助干扰消除过程，并提出了一种UAV-RIS辅助的干扰管理方案，该方案充分考虑了SAGIN中存在的多种CSI类型。在该方案中，卫星、地面发射机和UAV-RIS基于各节点的特定CSI类型协作设计预编码矩阵。此外，针对不同用户数和收发天线配置的SAGIN场景，深入讨论了所提IM方案获得的自由度增益。仿真结果表明，在相同CSI类型下，所提IM方案优于现有无UAV-RIS的IM方案。结果还展示了在不同CSI类型下采用所提IM方案时网络容量的提升。