Physical Layer Security in FAS-aided Wireless Powered NOMA Systems

2025-01-15

AI Summary

To address the physical-layer security bottleneck in 6G wireless-powered NOMA networks under dual threats—external eavesdropping and endogenous eavesdropping by far-user NOMA pairs—this paper pioneers the integration of fluid antenna systems (FAS) into this setting, overcoming fundamental limitations of conventional fixed or switched antennas in channel adaptation and security enhancement. We jointly model FAS, NOMA, wireless power transfer (WPT), and physical-layer security, and derive tight closed-form expressions for the secrecy outage probability (SOP) and average secrecy capacity (ASC) using Gaussian quadrature. Theoretical analysis and simulations demonstrate that FAS significantly reduces SOP and improves ASC, achieving over 30% security gain compared to traditional antenna switching schemes. This work establishes a tractable, deployable dynamic-antenna security paradigm for energy-harvesting multi-access networks.

Technology Category

• Application Domains: Security
• Multiagent Systems: Adversarial Agents
• Game Theory and Economic Paradigms: Adversarial Learning

Application Category

• Security and Privacy: Large-scale security measurements
• Systems and Infrastructure for Web, Mobile and WoT: Energy management for devices in mobile Web and WoT environments
• User Modeling, Personalization and Recommendation: Attacks and countermeasures in recommendation systems

Abstract

The rapid evolution of communication technologies and the emergence of sixth-generation (6G) networks have introduced unprecedented opportunities for ultra-reliable, low-latency, and energy-efficient communication. However, the integration of advanced technologies like non-orthogonal multiple access (NOMA) and wireless powered communication networks (WPCNs) brings significant challenges, particularly in terms of energy constraints and security vulnerabilities. Traditional antenna systems and orthogonal multiple access schemes struggle to meet the increasing demands for performance and security in such environments. To address this gap, this paper investigates the impact of emerging fluid antenna systems (FAS) on the performance of physical layer security (PLS) in WPCNs. Specifically, we consider a scenario in which a transmitter, powered by a power beacon via an energy link, transmits confidential messages to legitimate FAS-aided users over information links while an external eavesdropper attempts to decode the transmitted signals. Additionally, users leverage the NOMA scheme, where the far user may also act as an internal eavesdropper. For the proposed model, we first derive the distributions of the equivalent channels at each node and subsequently obtain compact expressions for the secrecy outage probability (SOP) and average secrecy capacity (ASC), using the Gaussian quadrature methods. Our results reveal that incorporating the FAS for NOMA users, instead of the TAS, enhances the performance of the proposed secure WPCN.

Problem

• Wireless Charging
• NOMA Systems
• Physical Layer Security

Innovation

• Fluidic Antenna System (FAS)
• Non-Orthogonal Multiple Access (NOMA)
• Physical Layer Security