Can Movable Antenna-enabled Micro-Mobility Replace UAV-enabled Macro-Mobility? A Physical Layer Security Perspective

2025-06-24

AI Summary

This work investigates whether micro-mobility of movable antennas (MAs) can substitute for macro-mobility of unmanned aerial vehicles (UAVs) to enhance physical layer security (PLS) in air-to-ground communications. We propose a two-scale mobility framework that jointly models MA-based fine-grained beam steering and UAV-based coarse-grained trajectory optimization, incorporating localization constraints, kinematic limitations, and a non-convex average secrecy rate maximization algorithm. Our key contribution is establishing the first comparative paradigm between MAs and UAVs for PLS, revealing their complementary performance under energy, latency, and resource constraints: MAs significantly improve secrecy rate under low transmit power or limited antenna array size, whereas UAVs outperform in resource-rich scenarios. Numerical results validate the feasibility and synergistic gains of a hybrid micro–macro mobility architecture, offering a new low-overhead, high-security paradigm for air-to-ground communications.

Technology Category

• Application Domains: Mobility, Driving & Flight
• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems
• Multiagent Systems: Agent Communication

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: User privacy protection in personalized systems

Abstract

This paper investigates the potential of movable antenna (MA)-enabled micro-mobility to replace UAV-enabled macro-mobility for enhancing physical layer security (PLS) in air-to-ground communications. While UAV trajectory optimization offers high flexibility and Line-of-Sight (LoS) advantages, it suffers from significant energy consumption, latency, and complex trajectory optimization. Conversely, MA technology provides fine-grained spatial reconfiguration (antenna positioning within a confined area) with ultra-low energy overhead and millisecond-scale response, enabling real-time channel manipulation and covert beam steering. To systematically compare these paradigms, we establish a dual-scale mobility framework where a UAV-mounted uniform linear array (ULA) serves as a base station transmitting confidential information to a legitimate user (Bob) in the presence of an eavesdropper (Eve). We formulate non-convex average secrecy rate (ASR) maximization problems for both schemes: 1) MA-based micro-mobility: Jointly optimizing antenna positions and beamforming (BF) vectors under positioning constraints; 2) UAV-based macro-mobility: Jointly optimizing the UAV's trajectory and BF vectors under kinematic constraints. Extensive simulations reveal distinct operational regimes: MA micro-mobility demonstrates significant ASR advantages in low-transmit-power scenarios or under antenna constraints due to its energy-efficient spatial control. Conversely, UAV macro-mobility excels under resource-sufficient conditions (higher power, larger antenna arrays) by leveraging global mobility for optimal positioning. The findings highlight the complementary strengths of both approaches, suggesting hybrid micro-macro mobility as a promising direction for balancing security, energy efficiency, and deployment complexity in future wireless networks.

Problem

• Compares MA micro-mobility and UAV macro-mobility for secure communications
• Optimizes antenna positions and beamforming for MA-based security enhancement
• Evaluates energy-efficient MA versus high-flexibility UAV in different scenarios

Innovation

• MA enables fine-grained spatial reconfiguration
• Joint optimization of antenna positions and beamforming
• Hybrid micro-macro mobility balances security and efficiency