Subverting Flexible Multiuser Communications via Movable Antenna-Enabled Jammer

2025-10-17

AI Summary

In suspicious multi-user downlink communications, an adversary—termed the suspicious transmitter (ST)—dynamically adapts its transmit power to counteract jamming, leading to a non-cooperative interaction with the legitimate jammer. Method: This paper proposes a mobile-antenna-based intelligent jammer (MAJ) that jointly optimizes antenna placement and interference beamforming to minimize either the sum rate or the minimum rate of the suspicious users. A Stackelberg game model is formulated to capture the hierarchical interaction between the MAJ (leader) and the ST (follower). Contribution/Results: We analytically characterize optimal antenna deployment patterns and derive a tight lower bound on system capacity, along with the corresponding ideal deployment strategy. Simulation results demonstrate that, compared to conventional fixed-antenna jamming, the proposed MAJ reduces the sum rate and minimum rate by up to 32.7% and 41.5%, respectively. This work establishes a deployable, analytically tractable paradigm for physical-layer security.

Technology Category

• Multiagent Systems: Mechanism Design
• Planning, Routing, and Scheduling: Scheduling under Uncertainty
• Search and Optimization: Adversarial Search

Application Category

• User Modeling, Personalization and Recommendation: Attacks and countermeasures in recommendation systems
• 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

Abstract

Movable antenna (MA) is an emerging technology which can reconfigure wireless channels via adaptive antenna position adjustments at transceivers, thereby bringing additional spatial degrees of freedom for improving system performance. In this paper, from a security perspective, we exploit the MAenabled legitimate jammer (MAJ) to subvert suspicious multiuser downlink communications consisting of one suspicious transmitter (ST) and multiple suspicious receivers (SRs). Specifically, our objective is to minimize the benefit (the sum rate of all SRs or the minimum rate among all SRs) of such suspicious communications, by jointly optimizing antenna positions and the jamming beamforming at the MAJ. However, the key challenge lies in that given the MAJ's actions, the ST can reactively adjust its power allocations to instead maximize its benefit for mitigating the unfavorable interference. Such flexible behavior of the ST confuses the optimization design of the MAJ to a certain extent. Facing this difficulty, corresponding to the above two different benefits: i) we respectively determine the optimal behavior of the ST given the MAJ's actions; ii) armed with these, we arrive at two simplified problems and then develop effective alternating optimization based algorithms to iteratively solve them. In addition to these, we also focus on the special case of two SRs, and reveal insightful conclusions about the deployment rule of antenna positions at the MAJ. Furthermore, we analyze the ideal antenna deployment scheme at the MAJ for achieving the globally performance lower bound. Numerical results demonstrate the effectiveness of our proposed schemes compared to conventional fixed-position antenna (FPA) and other competitive benchmarks.

Problem

• Minimizing suspicious multiuser communication benefits using movable antenna jammers
• Optimizing antenna positions and jamming beamforming against reactive transmitters
• Developing algorithms to counteract adaptive power allocation in suspicious networks

Innovation

• Movable antenna reconfigures channels via position adjustments
• Joint optimization of antenna positions and jamming beamforming
• Alternating optimization algorithms solve simplified problems iteratively