Reconfigurable Intelligent Surfaces Empowered THz Communication in LEO Satellite Networks

The revolution in the low Earth orbit (LEO) satellite networks will bring changes to their communication models and a shift from the classical bent-pipe architectures to more sophisticated networking platforms. Thanks to technological advancements in microelectronics and micro-systems, the terahertz (THz) band has emerged as a strong candidate for inter-satellite links (ISLs) due to its promise of high data rates. Yet, the propagation conditions of the THz band need to be properly modeled and controlled by utilizing reconfigurable intelligent surfaces (RISs) to leverage their full potential. In this work, we first provide an assessment of the use of the THz band for ISLs and quantify the impact of misalignment fading on error performance. Then, in order to compensate for the high path loss associated with high carrier frequencies, and to further improve the signal-to-noise ratio (SNR), we propose the use of RISs mounted on neighboring satellites to enable signal propagation. Based on a mathematical analysis of the problem, we present the closed-form error rate expressions for RIS-assisted ISLs with misalignment fading. Numerical results demonstrate that the proposed RIS-empowered THz communication solution presents significant performance improvement with the use of RISs.