Hybrid Active-Passive Intelligent Reflecting Surface for Secure Communication

The intelligent reflecting surface (IRS) offers control over signal power and has been widely utilized in secure transmission systems to enhance physical layer security. This paper presents a novel approach that investigates a hybrid active-passive IRS-assisted secure communication system instead of focusing solely on either passive or active IRS. The transmit beamforming and reflection matrix of the passive/active IRS are jointly optimized to maximize the secrecy rate. An algorithm that combines the difference of convex algorithm, fractional programming, and minorization maximization methods is proposed to solve the joint optimization problem. Simulation results demonstrate that the proposed method significantly improves secrecy performance and outperforms systems with only passive or active IRS.