I. Introduction
THZ frequency bands (100 GHz - 10 THz) are considered cornerstones in the 6G communication networks. THz-frequencies are favorable to support ultra-high bandwidths and significant data rates. These frequency bands can potentially provide considerable performance gains and significant capacities. Nonetheless, the transition towards the real and practical implementation of THz networks suffers from molecular losses, highly dynamic and varying channels, short-range links and communication distances, and the reliance on line-of-sight (LOS) or narrow-beam links [1], [2]. To optimize the achievable data rate at the receiver (Rx), this research paper examines the reflecting intelligent surface (RIS) as a modern technology and promising solution. The RIS is a two-dimensional (2D) electromagnetic surface, precisely metasurface, that constitutes a large number of semi-passive scattering elements. Every element can be controlled via a software-defined behavior to adjust the electromagnetic properties (i.e. phase-shift) of the reflection of the incident radio frequency (RF) signals upon the RIS elements [3], [4]. Thus, the RIS can instantly amend the wireless propagation channel to improve the signal transmission, boost the received signal power, and suppress the interference at the Rx. Therefore, it improves the data rate in a cost-effective and energy-efficient behavior and provides an innovative means to attain the 6G Key performance indicators (KPIs) [5], [6].