Joint Beamforming Design for Secure RIS-Assisted IoT Networks

Hehao Niu, Zhi Lin, Zheng Chu, Zhengyu Zhu, Pei Xiao, Huan X. Nguyen, Inkyu Lee, Naofal Al-Dhahir

Research output: Journal PublicationArticlepeer-review

33 Citations (Scopus)


This article studies secure communication in an Internet of Things (IoT) network, where the confidential signal is sent by an active refracting reconfigurable intelligent surface (RIS)-based transmitter, and a passive reflective RIS is utilized to improve the secrecy performance of users in the presence of multiple eavesdroppers. Specifically, we aim to maximize the weighted sum secrecy rate by jointly designing the power allocation, transmit beamforming (BF) of the refracting RIS, and the phase shifts of the reflective RIS. To solve the nonconvex optimization problem, we propose a linearization method to approximate the objective function into a linear form. Then, an alternating optimization (AO) scheme is proposed to jointly optimize the power allocation factors, BF vector, and phase shifts, where the first one is found using the Lagrange dual method, while the latter two are obtained by utilizing the penalty dual decomposition method. Moreover, considering the demands of green and secure communications, by applying Dinkelbach's method, we extend our proposed scheme to solving a secrecy energy maximization problem. Finally, simulation results demonstrate the effectiveness of the proposed design.

Original languageEnglish
Pages (from-to)1628-1641
Number of pages14
JournalIEEE Internet of Things Journal
Issue number2
Publication statusPublished - 15 Jan 2023
Externally publishedYes


  • Alternating optimization (AO)
  • joint beamforming (BF)
  • penalty dual decomposition (PDD)
  • reconfigurable intelligent surface (RIS)
  • secure communication

ASJC Scopus subject areas

  • Signal Processing
  • Information Systems
  • Hardware and Architecture
  • Computer Science Applications
  • Computer Networks and Communications


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