In space-air-ground integrated networks (SAGIN), receivers experience diverse interference from both the satellite and terrestrial transmitters. The heterogeneous structure of SAGIN poses challenges for traditional interference management (IM) schemes to effectively mitigate interference. To address this, a novel UAV-RIS-aided IM scheme is proposed for SAGIN, where different types of channel state information (CSI) including no CSI, instantaneous CSI, and delayed CSI, are considered. According to the types of CSI, interference alignment, beamforming, and space-time precoding are designed at the satellite and terrestrial transmitter side, and meanwhile, the UAV-RIS is introduced for cooperating interference elimination process. Additionally, the degrees of freedom (DoF) obtained by the proposed IM scheme are discussed in depth when the number of antennas on the satellite side is insufficient. Simulation results show that the proposed IM scheme improves the system capacity in different CSI scenarios, and the performance is better than the existing IM benchmarks without UAV-RIS.

翻译：在空天地一体化网络（SAGIN）中，接收端同时遭受来自卫星和地面发射机的多种干扰。SAGIN的异构结构使得传统干扰管理（IM）方案难以有效抑制干扰。为此，提出一种针对SAGIN的新型无人机辅助RIS IM方案，该方案考虑了无信道状态信息（CSI）、瞬时CSI和延迟CSI等不同类型的CSI。根据CSI类型，在卫星和地面发射端设计干扰对齐、波束成形和时空预编码，同时引入UAV-RIS以协同干扰消除过程。此外，深入讨论了在卫星侧天线数不足时，所提IM方案获得的自由度（DoF）。仿真结果表明，所提IM方案在不同CSI场景下均能提升系统容量，且性能优于现有无UAV-RIS的IM基准方案。