Does Movable Antenna Present A Dual-edged Nature? From the Perspective of Physical Layer Security: A Joint Design of Fixed-position Antenna and Movable Antenna

2025-07-08

AI Summary

Fixed antenna arrays in artificial-noise-aided physical-layer security suffer from spatial coverage blind spots due to static configurations. Method: This paper proposes a hybrid deployment framework integrating fixed and mobile antennas, where mobile antennas dynamically reconfigure interference nulls in space—replacing conventional fixed artificial-noise generation—to simultaneously ensure baseline communication connectivity and enhance channel-level security. A joint optimization of mobile antenna positions and beamforming vectors for both fixed and mobile antennas is performed via Nesterov-accelerated projected gradient ascent combined with alternating optimization, solving the non-convex secure rate maximization problem. Contribution/Results: Experiments demonstrate that the proposed method improves secure rate by 42.34% over a purely fixed-antenna baseline and by 9.12% over a purely mobile-antenna baseline, significantly strengthening physical-layer security in dynamic environments.

Technology Category

• Search and Optimization: Mixed Discrete/Continuous Search
• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems
• Machine Learning: Hardware-aware ML

Application Category

• Security and Privacy: Large-scale security measurements
• Systems and Infrastructure for Web, Mobile and WoT: Applied ML and AI for Web-based mobile applications
• User Modeling, Personalization and Recommendation: Attacks and countermeasures in recommendation systems

Abstract

In conventional artificial noise (AN)-aided physical-layer security systems, fixed-position antenna (FPA) arrays exhibit inherent vulnerability to coverage gaps due to their static spatial configuration. Adversarial eavesdroppers can strategically exploit their mobility to infiltrate these spatial nulls of AN radiation patterns, thereby evading interference suppression and successfully intercepting the confidential communication. To overcome this limitation, in this paper, we investigate a hybrid antenna deployment framework integrating FPA arrays and movable antenna (MA) arrays (denoted by FMA co-design) to address the security performance in dynamic wireless environments, based on the fact that MA arrays enable channel reconfiguration through localized antenna repositioning, achieving more higher spatial degree of freedom (DoF). Enabled by FMA co-design framework, FPA arrays ensure baseline connectivity for legitimate links while MA arrays function as dynamic security enhancers, replacing conventional static AN generation. Furthermore, we formulate a non-convex optimization problem of the secrecy rate maximization through jointly optimizing MA positioning, FPA beamforming, and MA beamforming under practical constraints. the solution employs a dual-algorithm approach: Nesterov momentum-based projected gradient ascent (NMPGA) accelerates convergence in continuous position optimization, while alternating optimization (AO) handles coupled beamforming design. Experimental evaluations demonstrate that the proposed FMA co-design framework achieves significant secrecy performance gains over individual optimization benchmarks, yielding 42.34% and 9.12% improvements in secrecy rate compared to isolated FPA for AN generation and MA for confidential information baselines, respectively.

Problem

• Addresses vulnerability of fixed antennas to eavesdroppers in dynamic environments
• Proposes hybrid antenna design combining fixed and movable arrays for security
• Maximizes secrecy rate via joint optimization of antenna positioning and beamforming

Innovation

• Hybrid FPA and MA arrays for dynamic security
• Joint optimization of MA positioning and beamforming
• Dual-algorithm approach for secrecy rate maximization