HAPS-RIS or HAPS-Relay: Which Outperforms Under Impairments with NOMA in 6G NTN?

2026-09-09

AI Summary

本文研究了在NOMA方案下，HAPS辅助通信系统采用RIS或中继站时的性能表现，考虑了硬件损伤和信道状态信息不完美等实际问题。结果显示，RIS在总速率和能效上优于中继站。

Abstract

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.

Problem

• HAPS
• RIS
• Relay
• NOMA
• Impairments

Innovation

• HAPS-RIS
• NOMA
• Hardware Impairments
• Channel State Information
• Energy Efficiency