Intelligent Mixed Reflecting/Relaying Surface-Aided Secure Wireless Communications.

For intelligent reflecting surface (IRS)-aided networks, it is known that high network performance requires a large surface of IRS due to multiple path losses. Moreover, if a secure communication system wants to obtain a higher secrecy rate, more passive reflecting elements are needed, resulting in larger size of IRS. However, even though we increase more elements of IRS, we will face the problem of limited performance improvement. To solve this problem, we propose a secure communication architecture where an intelligent mixed reflecting/relaying surface (IMRRS) aids information transmission. We formulate the exact secrecy energy efficiency expression, and then aim to design an energy-efficient scheme to realize intelligent reflecting element (IRE) working mode selection and secure dynamic hybrid resource management. To address the formulated problem, we propose a fast IRE working mode selection method and a quantum-inspired bald eagle search (QBES) algorithm. Simulation results demonstrate the superiority of the proposed method, which can exploit the IMRRS benefits and improve security performance during information transmission.