Digital Twin for Metasurface Reflector Management in 6G Terahertz Communications

The performance demands from data-intensive applications, such as multimedia streaming, as well as the growing number of devices connecting to the Internet, will increase the need for higher capacity wireless communication links. The research community has recently explored regions of the spectrum, including the Terahertz band (0.1 THz to 10 THz), that are underutilised for communications. THz frequencies come with a plethora of special challenges, one of which is the very narrow effective beam, thereby requiring a Line of Sight (LoS) between sender and receiver. Researchers have explored the use of reflectors that can redirect beams around blockages. In this paper, we propose a THz signal guidance system where a Digital Twin is used to model, predict and control the signal propagation characteristics of an indoor space. Our approach finds the best THz signal path from the base station to the mobile target via the tunable metamaterial walls, avoiding obstacles as needed, using geometric (ray tracing), path loss and Terahertz Potential Field (THzPF) models. With this knowledge, the digital twin guides the selection of antenna strips at a base station and the reflectors along the signal path. A top-view camera, with advanced image processing, provides context updates (obstacle and mobile target locations) to the digital twin. The image processing system also senses factors like water vapour concentration, and the material composition and surface roughness of obstacles. Such factors affect propagation strength, and the digital twin modifies the beam paths to adapt. Simulation results have shown the efficiency of our control system to maintain a reliable signal connection while minimising the use of antenna and reflector strips. Our system is the first proposal that maximises THz signal-to-noise ratio (SNR) through such a dynamic and robust control system, which integrates image processing of a room with base station configuration

Artificial Potential Field Assisted Mirror Reflectors for Terahertz Communications

The expectation for higher capacity wireless communication links is ever increasing due to the demand for high-data intensive applications, such as multimedia streaming, as well as increased number of devices connecting to the Internet. Researchers have now recently explored regions of the spectrum that are under utilized for communications, and this is the Terahertz band (0.1 THz to 10 THz). Unlike wireless technologies today, THz frequencies come with a plethora of challenges, one of which is the requirement of constant LoS. A number of solutions have explored the use of reflectors, or even reflect-arrays, that can help assist in redirecting beams towards the mobile devices in order to avoid blockages. In this paper, we propose the use of the Artificial Potential Field concept to increase the LoS rays in a multi-ray link by controlling antenna strips selection of a base station. Our approach aims to ensure a clear THz signal path from the base station to the reflectors, and to the mobile. We also consider micro-movement events that may result in loss of connectivity, through a concept of Personal Zones that allows multiple THz rays to beam around a user. Simulation results have shown the efficiency of the Artificial Potential Field (APF) in assisting the mirrors to redirect their beams through smaller number of utilized antenna strips, which increases the signal-to-noise ratio of links

Simulation of Signal Coverage for Terahertz Communications

Recent progress in wireless communication technology has started to see proposals for spectrum operation in the Terahertz band (0.1 THz to 10 THz), which will lead to data rates close to Terabit per second (Tbps). However,there are a number of challenges with the signals operating in the THz band, and this includes the requirements of Line-of-sight, signal attenuation due to molecular absorption, as well as signal scattering upon reflection from rough surfaces. This paper addresses a software-defined reflector solution for mirror-assisted terahertz communications. The paper also discusses future outlook that further improve reflectos for terahertz communications