Secure multigroup multicast communication systems via intelligent reflecting surface

• Published in: China communications Vol. 18; no. 3; pp. 39 - 51
• Main Authors: Shi, Weiping, Li, Jiayu, Xia, Guiyang, Wang, Yuntian, Zhou, Xiaobo, Zhang, Yonghui, Shu, Feng
• Format: Journal Article
• Language: English
• Published: China Institute of Communications 01.03.2021; School of Electronic and Optical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China; School of Electronic and Electrical Engineering, Shangqiu Normal University, Shangqiu 476000, China%School of Electronic and Optical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China%School of Physics and Electronic Engineering, Fuyang Normal University, Fuyang 236037, China%School of Information and Communication Engineering, Hainan University, Haikou 570228, China%School of Information and Communication Engineering, Hainan University, Haikou 570228, China
• Subjects: Array signal processing; Communication system security; intelligent reflecting surface; Interference; MISO communication; multigroup multicast; Optimization; phase shifts; secrecy rate; Transforms; transmit beamformer; Wireless communication; intelligent reflecting surface; multigroup multicast; secrecy rate; transmit beamformer; phase shifts
• ISSN: 1673-5447
• DOI: 10.23919/JCC.2021.03.004

This paper considers a secure multigroup multicast multiple-input single-output (MISO) communication system aided by an intelligent reflecting surface (IRS). Specifically, we aim to minimize the transmit power at Alice via jointly optimizing the transmit beamformer, artificial noise (AN) vector and phase shifts at the IRS subject to the secrecy rate constraints as well as the unit modulus constraints of IRS phase shifts. To tackle the optimization problem, we first transform it into a semidefinite relaxation (SDR) problem, and then alternately update the transmit beamformer and AN matrix as well as the phase shifts at the IRS. In order to reduce the high computational complexity, we further propose a low-complexity algorithm based on second-order cone programming (SOCP). We decouple the optimization problem into two sub-problems and optimize the transmit beamformer, AN vector and the phase shifts alternately by solving two corresponding SOCP subproblem. Simulation results show that the proposed SDR and SOCP schemes require half or less transmit power than the scheme without IRS, which demonstrates the advantages of introducing IRS and the effectiveness of the proposed methods.