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），传统干扰管理方案难以有效应对干扰。本文引入一种搭载有源智能超表面（RIS）的无人机（UAV-RIS）来辅助干扰消除过程。进一步，提出一种考虑SAGIN中多种CSI类型的UAV-RIS辅助干扰管理方案。在该方案中，卫星、地面发射机和UAV-RIS基于各节点的特定CSI类型协同设计预编码矩阵。此外，针对不同用户数与收发天线配置的SAGIN场景，深入讨论了所提干扰管理方案获得的自由度增益。仿真结果表明，在相同CSI类型下，所提方案优于现有不含UAV-RIS的干扰管理方案。结果还展示了在不同CSI类型下采用所提方案时网络的容量提升效果。