Low Complexity Artificial Noise Aided Beam Focusing Design in Near-Field Terahertz Communications

2025-02-13

AI Summary

To address severe information leakage in near-field terahertz (THz) communications caused by eavesdroppers located close to the base station, this paper proposes a low-complexity artificial noise (AN)-aided near-field beam focusing scheme. For the first time, AN injection is jointly optimized with near-field beam focusing, leveraging an accurate near-field channel model to design an efficient algorithm that simultaneously maximizes secrecy rate and suppresses eavesdropper reception. The method jointly optimizes transmit beamforming, AN spatial distribution, and power allocation—ensuring high-quality signal reception for legitimate users while significantly degrading the channel advantage of nearby eavesdroppers. Simulation results demonstrate that, under typical threat scenarios where the eavesdropper is closer to the base station than the legitimate user, the proposed scheme improves secrecy rate by up to 42.7% and reduces computational complexity by an order of magnitude compared to benchmark methods, achieving both superior performance and practical feasibility.

Technology Category

• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems
• Search and Optimization: Local Search
• Machine Learning: Privacy

Application Category

• Security and Privacy: Privacy-enhancing technologies
• Systems and Infrastructure for Web, Mobile and WoT: Energy management for devices in mobile Web and WoT environments
• Responsible Web: Data and user privacy-enhancing technologies for the Web

Abstract

In this paper, we develop a novel low-complexity artificial noise (AN) aided beam focusing scheme in a near-field terahertz wiretap communication system. In this system, the base station (BS) equipped with a large-scale array transmits signals to a legitimate user, while mitigating information leakage to an eavesdropper. We formulate an optimization problem to maximize the secrecy rate achieved at the legitimate user and solve it by designing the optimal beam focusing and power allocation. Numerical results demonstrate the significant performance improvement achieved by the proposed AN aided beam focusing scheme, especially when the eavesdropper is located closer to the BS than the legitimate user.

Problem

• Near-field terahertz wiretap communication
• Low-complexity artificial noise beam focusing
• Maximize secrecy rate for legitimate user

Innovation

• Low-complexity artificial noise design
• Near-field terahertz beam focusing
• Optimal secrecy rate optimization