Performance Comparison of Aerial RIS and STAR-RIS in 3D Wireless Environments

TL;DR

This paper compares aerial RIS and STAR-RIS in 3D wireless environments, analyzing their performance, optimization, and deployment strategies for future 6G networks.

Contribution

It provides a comprehensive performance comparison, accurate channel modeling, and optimization solutions for aerial RIS and STAR-RIS architectures.

Findings

STAR-RIS outperforms RIS at low altitudes due to full-space coverage

RIS performs better near the base station at higher altitudes

Optimization algorithms improve system sum-rate in both architectures

Abstract

Reconfigurable intelligent surface (RIS) and simultaneously transmitting and reflecting RIS (STAR-RIS) have emerged as key enablers for enhancing wireless coverage and capacity in next-generation networks. When mounted on unmanned aerial vehicles (UAVs), they benefit from flexible deployment and improved line-of-sight conditions. Despite their promising potential, a comprehensive performance comparison between aerial RIS and STAR-RIS architectures has not been thoroughly investigated. This letter presents a detailed performance comparison between aerial RIS and STAR-RIS in three-dimensional wireless environments. Accurate channel models incorporating directional radiation patterns are established, and the influence of deployment altitude and orientation is thoroughly examined. To optimize the system sum-rate, we formulate joint optimization problems for both architectures and propose an efficient solution based on the weighted minimum mean square error and block coordinate descent algorithms. Simulation results reveal that STAR-RIS outperforms RIS in low-altitude scenarios due to its full-space coverage capability, whereas RIS delivers better performance near the base station at higher altitudes. The findings provide practical insights for the deployment of aerial intelligent surfaces in future 6G communication systems.