HAPS with intelligent surfaces outperform relays for 6G communication
HAPS-RIS or HAPS-Relay: Which Outperforms Under Impairments with NOMA in 6G NTN?
Networking and Internet Architecture
Summary
This paper looks at new ways to improve high-altitude communication systems for 6G networks. It compares two approaches: using smart reflective surfaces (RIS) or relay stations (RS) on high platforms. The authors find that smart surfaces work better in real-world imperfect conditions because they don’t add extra noise like relays do. They also show that how devices and users are arranged affects performance, and adding more smart surface elements helps overcome some problems with imperfect information about the connection.
What this means in practice
- •For network engineers: Design high-altitude 6G links using RIS to improve communication speed and energy use under real hardware limitations.
- •For telecommunications planners: Plan user layouts and allocate RIS elements to maximize 6G network performance in non-ideal conditions.
Authors
Bilal Karaman, Faicel Khennoufa, Ilhan Basturk, Metin Ozturk, Ferdi Kara, Sezai Taskin, Halim Yanikomeroglu
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.