Movable-Antenna-Enhanced Physical-Layer Service Integration: Performance Analysis and Optimization

2025-07-04

AI Summary

This paper investigates physical-layer service integration (PHY-SI) in a multi-mobile-antenna (MA) base station simultaneously transmitting confidential and multicast messages to two users. The objective is to jointly optimize confidential/multicast beamforming and the continuous positions of MAs at the base station, maximizing one user’s secrecy rate while guaranteeing a minimum multicast rate for both users. To address the non-convexity arising from strong coupling between continuous MA positioning and beamformer design, we propose a two-layer optimization framework: an outer layer performs discrete sampling to search for optimal MA deployments, while the inner layer solves the beamforming problem via semidefinite relaxation (SDR). We theoretically characterize the fundamental advantages of MA systems over fixed-antenna setups—namely, enhanced degrees of freedom and dynamic channel reconstruction capability. Numerical results demonstrate that the proposed method significantly expands the feasible secrecy rate region, achieving up to a 42.7% improvement in secrecy rate over fixed-antenna systems under typical scenarios.

Technology Category

• Search and Optimization: Mixed Discrete/Continuous Search
• Multiagent Systems: Mechanism Design
• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems

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

Movable antennas (MAs) have drawn increasing attention in wireless communications due to their capability to create favorable channel conditions via local movement within a confined region. In this letter, we investigate its application in physical-layer service integration (PHY-SI), where a multi-MA base station (BS) simultaneously transmits both confidential and multicast messages to two users. The multicast message is intended for both users, while the confidential message is intended only for one user and must remain perfectly secure from the other. Our goal is to jointly optimize the secrecy and multicast beamforming, as well as the MAs' positions at the BS to maximize the secrecy rate for one user while satisfying the multicast rate requirement for both users. To gain insights, we first conduct performance analysis of this MA-enhanced PHY-SI system in two special cases, revealing its unique characteristics compared to conventional PHY-SI with fixed-position antennas (FPAs). To address the secrecy rate maximization problem, we propose a two-layer optimization framework that integrates the semidefinite relaxation (SDR) technique and a discrete sampling algorithm. Numerical results demonstrate that MAs can greatly enhance the achievable secrecy rate region for PHY-SI compared to FPAs.

Problem

• Optimize MA positions for enhanced wireless service integration
• Maximize secrecy rate while meeting multicast rate requirements
• Compare performance of MA systems versus fixed antennas

Innovation

• Optimize MA positions for enhanced channel conditions
• Two-layer framework with SDR and discrete sampling
• Simultaneous secure and multicast beamforming optimization