Enhanced Sum rate in IRS-THz System using Hybrid Iterative Optimization Algorithm

Fatima, Shahnaz; Anand, Vatsala; Thodupunoori, Padmavathi; Putchakayala, Venkateswara Rao; Relangi, Anil Kumar; Gudivada Abraham, Arun Kumar; Utla Surya Bhadra Kanaka, Mahalaxmi

doi:10.24271/psr.2025.504030.1928

Enhanced Sum rate in IRS-THz System using Hybrid Iterative Optimization Algorithm

Document Type : Original Article

Authors

Shahnaz Fatima ¹

Vatsala Anand ²

Padmavathi Thodupunoori ³

Venkateswara Rao Putchakayala ⁴

Anil Kumar Relangi ⁵

Arun Kumar Gudivada Abraham

Mahalaxmi Utla Surya Bhadra Kanaka

¹ Department of Electronics and Communication Engineering, SASI Institute of Technology and Engineering, Tadepalligudem 53410, India.

² Chitkara University Institute of Engineering and Technology, Chitkara University, Rajpura 140401, Punjab.

³ Department of Electronics and Communication Engineering, CVR College of Engineering, Hyderabad 501510, India.

⁴ Department of Electronics and Communication Engineering, Lakireddy Bali Reddy College of Engineering, Mangalpalle, Telangana 501510, India.

⁵ Department of Electronics and Communication Engineering, Aditya University, Surampalem 533437, India.

10.24271/psr.2025.504030.1928

Abstract

This paper presents the use of intelligent reflecting surfaces (IRS) in terahertz (THz) communication systems. IRS is a promising technology to address challenges in THz communications such as severe path loss and limited scattering. However, the frequency-independent nature of IRS elements leads to beam squint effect in wideband THz systems. Mainly focusing on the impact of time delays. We propose a joint beamforming optimization framework to maximize the weighted Sum rate (WSR). This includes optimized base station beamforming, IRS reflection coefficients and time delays. The optimization problem is divided into subproblems, solved using techniques such as successive convex approximation (SCA), semidefinite relaxation (SDR) and fractional programming (FP). A Hybrid Iterative Optimization Algorithm iteratively achieves convergence.

Simulation results show that our approach mitigates beam squint effects, enhancing system performance compared to conventional methods. The findings highlight the effectiveness of incorporating time delays into IRS design. This implementation offers a pathway to robust THz communication systems. From the simulation results, with 130 IRS elements, the Hybrid Scheme achieves a Sum rate of 55 bps/Hz. This is 37% higher than the SDR Scheme and 83% higher than the SCA Scheme. For bandwidth between 10 GHz and 20 GHz, the hybrid Scheme maintains a stable performance of around 700 bps/Hz. It is over 2.3 times higher than the SDR Scheme and nearly 3.5 times higher than the SCA Scheme.

Keywords

Terahertz

Intelligent reflecting surfaces. Successive convex approximation

Semidefinite relaxation