QoS-Constrained Energy-Efficient Beamforming and Jamming with Intelligent Reflecting Surface for Secure Multi-User Downlink

Abstract

In this paper, we propose an intelligent reflecting surface (IRS)-aided secure multi-user downlink, where a single base station with multiple antennas sends information and artificial noises with the aid of transmit beamforming and jamming in the presence of multiple eavesdroppers. We investigate the quality-of-service (QoS)-constrained formulation of an optimization problem of beamforming weights, jamming matrix, and the IRS's phase shifts in order to reduce the total transmit power while satisfying the constraint of a target secrecy rate. To solve the non-convex optimization problem of our framework, we propose an efficient alternating optimization-based iterative algorithm, where the original non-convex problem is divided into sub-problems. Our performance results demonstrate that the proposed scheme is capable of minimizing the transmit power at the base station while satisfying a target secrecy rate.