Energy-efficient Resource Allocation for Secure IRS Networks with an Active Eavesdropper

In this paper, in order to solve poor communication problems under the long-distance transmission and secure communication, an energy-efficient maximization based resource allocation (RA) algorithm is proposed to improve system energy efficiency (EE) and information security for secure intelligent reflecting surface-based cellular networks under an active eavesdropper. Firstly, a nonlinear RA model with coupled variables (i.e., beamforming vector and phase shift matrix) is formulated for a multiple-input single-output cellular system with the help of IRS, where the minimum secure rate constraint of user, the maximum transmit power constraint of base station (BS), and continuous phase shift constraint are considered simultaneously. Then, the fractional objective function is transformed into a parameter-subtractive form by using Dinkelbach's approach, meanwhile the coupled beamforming vector and the phase shift parameter are decoupled by using an alternating iteration method. Moreover, the non-convex problem is converted into a semi-definite programming problem solved by using convex optimization tools. Finally, simulation results demonstrate the proposed algorithm has good EE and security.

I. Introduction

With the development of various communication technologies, the transmission rate of wireless networks has made a qualitative leap, such as massive multi-input multi-output, millimeter-wave communication, etc. However, energy consumption and hardware cost of communication network are still urgent problems [1], [2]. Compared with the traditional fourth-generation (4G) technology, the fifth-generation (5G) communication can improve transmission efficiency, but it causes more energy consumption and the cost of network infrastructure [3].