Secure multigroup multicast communication systems via intelligent reflecting surface

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 beamformer, artificial noise (AN) vector and phase shifts IRS subject secrecy rate constraints as well unit modulus of shifts. To tackle optimization problem, first transform it into semidefinite relaxation (SDR) then alternately update beamformer AN matrix IRS. In order reduce high computational complexity, further propose low-complexity algorithm based on second-order cone programming (SOCP). We decouple problem two sub-problems optimize solving corresponding SOCP subproblem. Simulation results show that proposed SDR schemes require half or less than scheme without IRS, which demonstrates advantages introducing effectiveness methods.