Design and Performance Analysis of Hybrid FSO/THz Relay with Aerial RIS for Future NTN-Integrated 6G Wireless Communications

TL;DR

This paper proposes a hybrid FSO/THz relay with aerial RIS for 6G networks, deriving performance metrics and demonstrating significant improvements over traditional systems through analytical and simulation validation.

Contribution

It introduces a novel hybrid FSO/THz relay system with aerial RIS, providing closed-form performance expressions and analyzing the impact of system parameters for 6G applications.

Findings

Hybrid model improves performance by 52.54% over traditional RF-FSO.

Aerial RIS enhances system performance by 41.39%.

Optimal RIS placement at lower altitude improves overall performance.

Abstract

In the context of emerging sixth-generation (6G) wireless networks, reconfigurable intelligent surfaces (RISs) are gaining prominence for their ability to intelligently control electromagnetic wave propagation and enhance backhaul communication performance. In this paper, we propose a novel dual-hop wireless network, where the first hop consists of a hybrid free-space optics (FSO) / terahertz (THz) link, and the second hop incorporates an aerial RIS-based radio frequency (RF) link. To provide a comprehensive performance evaluation, a comparative analysis of two switching strategies is conducted: (1) hard switching and (2) soft switching. Novel closed-form expressions are derived for key performance metrics, including outage probability and bit error rate. These expressions are then utilized to investigate the impact of various system parameters. Our proposed hybrid model demonstrates a 52.54% performance improvement over the traditional RF-FSO framework. Moreover, the integration of an aerial RIS in the second hop enhances system performance by 41.39%. Numerical findings suggest that strategically placing the aerial RIS at a lower altitude and maintaining an equal, shorter distance from both communication endpoints significantly improves overall system performance. To analyze the response under high signal-to-noise ratio (SNR) conditions, asymptotic analysis is performed, and the diversity order of the system is determined. Finally, the analytical results are validated through a Monte Carlo simulation.