Secrecy Rate Maximization for Movable Antenna-Aided STAR-RIS in Integrated Sensing and Communication Systems

Area of Science:

• Wireless communication systems
• Signal processing
• Information security

Background:

• Integrated sensing and communication (ISAC) systems benefit from movable antennas (MAs) and simultaneously transmitting and reflecting reconfigurable intelligent surfaces (STAR-RISs).
• Existing research has not fully utilized the spatial flexibility of MAs and the extended coverage of STAR-RIS to address security challenges in ISAC.

Purpose of the Study:

• To propose a novel MA- and STAR-RIS-assisted secure ISAC system.
• To maximize the minimum secrecy rate in a system with multiple legitimate users and potential eavesdroppers.
• To jointly optimize base station (BS) active beamforming, STAR-RIS passive beamforming, and MA positions.

Main Methods:

• Formulation of a minimum secrecy rate maximization problem.
• Development of an iterative algorithm using the alternating optimization (AO) framework.
• Application of semidefinite relaxation (SDR) and successive convex approximation (SCA) techniques to solve complex subproblems, including MA position optimization.

Main Results:

• The proposed MA and STAR-RIS-assisted scheme demonstrates significantly enhanced secure performance compared to benchmark schemes.
• The joint optimization of beamforming and MA positions effectively improves system security.
• The iterative algorithm effectively handles the non-convex optimization challenges.

Conclusions:

• The proposed approach effectively enhances the security of ISAC systems by leveraging MAs and STAR-RIS.
• The developed optimization techniques provide a viable solution for complex secure ISAC system design.
• The integration of spatial flexibility and advanced beamforming offers substantial security benefits.