Multi-Wideband Terahertz Communications via Tunable Graphene-based Metasurfaces in 6G Networks

TL;DR

This paper assesses the potential of tunable graphene-based reconfigurable intelligent surfaces for multi-wideband terahertz communications in 6G networks, demonstrating beam steering capabilities across multiple THz bands.

Contribution

It proposes a tunable graphene-based RIS design for multi-wideband THz operation and evaluates its performance for 6G indoor scenarios.

Findings

Numerical evaluation shows effective beam steering at 0.65, 0.85, and 1.05 THz.

Tunable graphene RIS can operate across multiple THz transparency windows.

Challenges in fabrication and design for multi-band THz RIS are discussed.

Abstract

The next generation of wireless networks is expected to tap into the terahertz (0.1--10 THz) band to satisfy the extreme latency and bandwidth density requirements of future applications. However, the development of systems in this band is challenging as THz waves confront severe spreading and penetration losses, as well as molecular absorption, which leads to strong line-of-sight requirements through highly directive antennas. Recently, reconfigurable intelligent surfaces (RISs) have been proposed to address issues derived from non-line-of-sight propagation, among other impairments, by redirecting the incident wave toward the receiver and implementing virtual-line-of-sight communications. However, the benefits provided by a RIS may be lost if the network operates at multiple bands. In this position paper, the suitability of the RIS paradigm in indoor THz scenarios for 6G is assessed grounded on the analysis of a tunable graphene-based RIS that can operate in multiple wideband transparency windows. A possible implementation of such a RIS is provided and numerically evaluated at 0.65/0.85/1.05 THz separately, demonstrating that beam steering and other relevant functionalities are realizable with excellent performance. Finally, the challenges associated with the design and fabrication of multi-wideband graphene-based RISs are discussed, paving the way to the concurrent control of multiple THz bands in the context of 6G networks.