Beyond Diagonal IRS Assisted Ultra Massive THz Systems: A Low Resolution Approach

TL;DR

This paper explores a low-resolution, beyond diagonal IRS approach to improve spectral efficiency in terahertz communication systems, addressing complexity challenges with an iterative solution.

Contribution

It introduces a novel joint precoding and phase shift design for BD-IRS with 1-bit resolution, optimizing spectral efficiency in terahertz systems.

Findings

Significant spectral efficiency improvement over diagonal IRS systems

Effective iterative solution for complex non-linear optimization

Low-resolution BD-IRS reduces cost and energy consumption

Abstract

The terahertz communications have the potential to revolutionize data transfer with unmatched speed and facilitate the development of new high-bandwidth applications. This paper studies the performance of downlink terahertz system assisted by beyond diagonal intelligent reconfigurable surface (BD-IRS). For enhanced energy efficiency and low cost, a joint precoding and BD-IRS phase shift design satisfying the $1$-bit resolution constraints to maximize the spectral efficiency is presented. The original problem is non-linear, NP-hard, and intricately coupled, and obtaining an optimal solution is challenging. To reduce the complexity, we first transform the optimization problem into two problems and then iteratively solve them to achieve an efficient solution. Numerical results demonstrate that the proposed approach for the BD-IRS assisted terahertz system significantly enhances the spectral efficiency compared to the conventional diagonal IRS assisted system.