HAPS-RIS 还是 HAPS-Relay：在 6G NTN 中 NOMA 受损情况下哪个性能更优？
HAPS-RIS or HAPS-Relay: Which Outperforms Under Impairments with NOMA in 6G NTN?
- Manisa Celal Bayar University（马尼萨杰拉勒巴亚尔大学）
- National Higher School of Advanced Technologies (ENSTA)（国立高等先进技术学院）
- Ankara Yıldırım Beyazıt University（安卡拉伊尔迪勒姆贝亚齐特大学）
- Ericsson Research（爱立信研究）
- Carleton University（卡尔顿大学）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本文对比 HAPS-RIS 与 HAPS-Relay 在 NOMA 及硬件损伤、不完美 CSI 下的性能，发现 HAPS-RIS 因无源特性在总速率和能效上更优，并通过大规模 RIS 部署补偿 CSI 敏感性，为 6G 设计提供指导。
AI中文摘要：
本文研究了在非正交多址（NOMA）方案下，采用可重构智能表面（RIS）或中继站（RS）的高空平台站（HAPS）辅助通信系统的性能。明确考虑了实际系统损伤，包括硬件损伤（HWI）和不完美信道状态信息（CSI）。结果表明，在非理想条件下，HAPS-RIS 在总速率和能量效率方面均优于 HAPS-RS，这归因于其无源特性，避免了噪声放大。此外，研究证明 RIS 元素分配和用户空间分布显著影响 NOMA 性能，其中增加用户分离度和适当分配可增强信道差异并提高系统效率。尽管 HAPS-RIS 对不完美 CSI 更为敏感，但通过大规模部署 RIS 元素，它能有效补偿性能下降，并保持相对于半双工 RS 系统的性能优势。这些见解为受损感知的 HAPS 辅助 6G 通信系统提供了有用的设计指导。
英文摘要：
This paper investigates the performance of high-altitude platform station (HAPS)-assisted communication systems employing either reconfigurable intelligent surfaces (RIS) or relay stations (RS) under non-orthogonal multiple access (NOMA) scheme. Practical system impairments, including hardware impairments (HWI) and imperfect channel state information (CSI), are explicitly considered. The results show that HAPS-RIS outperforms HAPS-RS in terms of both sum-rate and energy efficiency under non-ideal conditions due to its passive nature, which avoids noise amplification. Furthermore, it is demonstrated that RIS element allocation and user spatial distribution significantly impact NOMA performance, where increased user separation and proper allocation enhance channel disparity and improve system efficiency. Despite its higher sensitivity to imperfect CSI, HAPS-RIS can effectively compensate for performance degradation through large-scale RIS element deployment, maintaining a performance advantage over half-duplex RS-based systems. These insights provide useful design guidelines for impairment-aware HAPS-assisted 6G communication systems.
