Robust and Secure Wireless Communications via Intelligent Reflecting Surfaces

Yu, Xianghao; Xu, Dongfang; Sun, Ying; Ng, Derrick Wing Kwan; Schober, Robert

doi:10.1109/jsac.2020.3007043

Cited by 650 publications

(436 citation statements)

References 44 publications

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“…In the literature, there have been some recent works that studied robust beamforming designs for IRS-aided communication systems under imperfect CSI [17], [21]- [25], which are generally based on three different design approaches according to the assumed CSI error model. Firstly, the worst-case performance optimization approach was adopted in [21], [22] to design the active and passive beamforming jointly, by assuming the bounded CSI error model for partial channel uncertainty. The second approach adopted a probabilistic CSI error model (such as Gaussian distributed) and considered the average QoS performance [17], [23], [24].…”

Section: Introductionmentioning

confidence: 99%

Robust Beamforming Design for Intelligent Reflecting Surface Aided MISO Communication Systems

Zhou

Pan

Ren

et al. 2020

IEEE Wireless Commun. Lett.

280

202

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In intelligent reflecting surface (IRS) aided wireless communication systems, channel state information (CSI) is crucial to achieve its promising passive beamforming gains. However, CSI errors are inevitable in practice and generally correlated over the IRS reflecting elements due to the training with discrete phase shifts, which degrade the data transmission rate and reliability. In this paper, we focus on investigating the effect of CSI errors to the outage performance in an IRS-aided multiuser downlink communication system. Specifically, we aim to jointly optimize the active transmit precoding vectors at the access point (AP) and passive discrete phase shifts at the IRS to minimize the AP's transmit power, subject to the constraints on the maximum CSI-error induced outage probability for the users. First, we consider the single-user case and derive the user's outage probability in terms of the mean signal power (MSP) and variance of the received signal at the user. Since there is a trade-off in tuning these two parameters to minimize the outage probability, we propose to maximize their weighted sum with the optimal weight found by one-dimensional search. Then, for the general multiuser case, since the users' outage probabilities are difficult to obtain in closed-form due to the inter-user interference, we propose a novel constrained stochastic successive convex approximation (CSSCA) algorithm, by replacing the nonconvex outage probability constraints with properly designed convex surrogate approximations. Simulation results verify the effectiveness of the proposed robust beamfoming algorithms, and show their significant performance improvement over various benchmark schemes.

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Section: Introductionmentioning

confidence: 99%

Robust Beamforming Design for Intelligent Reflecting Surface Aided MISO Communication Systems

Zhou

Pan

Ren

et al. 2020

IEEE Wireless Commun. Lett.

280

202

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“…Recently, some efforts have been made to study the IRSaided system for physical layer security. In [22], [23], [28], the problem of maximizing the secrecy rate in an IRS-aided secure MISO communication system is investigated. An alternate optimization strategy was proposed to optimize the transmit beamforming vector at the BS and the phase shifts at the IRS.…”

Section: A Related Workmentioning

confidence: 99%

“…Since (19f) is non-convex, problem (22) is difficult to solve for traditional methods. Hence, we adopt the alternating optimization algorithm and divide (22) into two subproblems, i.e.…”

Section: B Manifold Optimization Algorithmmentioning

confidence: 99%

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Secure Wireless Transmission for Intelligent Reflecting Surface-Aided Millimeter-Wave Systems

Xiu

Zhang

2020

IEEE Access

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Due to the broadcast nature of millimeter wave (mmWave) communications, physical layer security has always been a fundamental but challenging concern. Fortunately, the recent advance of intelligent reflecting surface (IRS) introduces another dimension for mmWave secure communications by reconfiguring the transmission environments. In this paper, we investigate the physical layer security issue for IRS-aided mmWave communications. Specifically, two scenarios are considered, i.e., with and without the knowledge of the eavesdropper's channel. When the eavesdropper's channel is known, under the unit modulus constraints at the IRS and the transmit power constraint at the access point (AP), the secrecy rate is maximized by jointly designing the beamforming vector of the AP and the phase shifts of the IRS. We propose an alternating optimization algorithm for improving the secrecy rate to solve the non-convex optimization problem. In particular, the phase shift matrix of the IRS is firstly optimized based on the manifold optimization algorithm. Under the given phase shift matrix of the IRS, the original problem is transformed into a difference of convex (DC) programming problem. To solve this problem, we use the successive convex approximation (SCA)-based method to transform the original problem into a convex approximation problem, and the transmit beamforming vector is obtained by solving the convex approximation problem. In addition, when the eavesdropper's channel is unknown, under the transmit power constraint and the minimum user rate constraint, an artificial-noise (AN)-aided scheme is proposed to jam the eavesdropper by maximizing the AN power. Numerical results evaluate that the performance of our proposed schemes is better than that of the conventional scheme in terms of secrecy rate. Moreover, simulations also demonstrate that the secrecy behaviors of the IRS-aided mmWave communication system are superior to the mmWave communications without IRS.

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“…Such metasurfaces bounce signals between the base station and mobile endpoint, to avoid obstacles or environments that would otherwise attenuate or even block THz signals. Current research frontiers include programmable metamaterials for re-directing beams [11] [12] [13], mechanical control reflectors [14], [15] as well as protocols for security [16]. Fig.…”

Section: Introductionmentioning

confidence: 99%

Digital Twin for Metasurface Reflector Management in 6G Terahertz Communications

et al. 2020

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The performance demands from data-intensive applications, such as multimedia streaming, as well as the growing number of devices connecting to the Internet, will increase the need for higher capacity wireless communication links. The research community has recently explored regions of the spectrum, including the Terahertz band (0.1 THz to 10 THz), that are underutilised for communications. THz frequencies come with a plethora of special challenges, one of which is the very narrow effective beam, thereby requiring a Line of Sight (LoS) between sender and receiver. Researchers have explored the use of reflectors that can redirect beams around blockages. In this paper, we propose a THz signal guidance system where a Digital Twin is used to model, predict and control the signal propagation characteristics of an indoor space. Our approach finds the best THz signal path from the base station to the mobile target via the tunable metamaterial walls, avoiding obstacles as needed, using geometric (ray tracing), path loss and Terahertz Potential Field (THzPF) models. With this knowledge, the digital twin guides the selection of antenna strips at a base station and the reflectors along the signal path. A top-view camera, with advanced image processing, provides context updates (obstacle and mobile target locations) to the digital twin. The image processing system also senses factors like water vapour concentration, and the material composition and surface roughness of obstacles. Such factors affect propagation strength, and the digital twin modifies the beam paths to adapt. Simulation results have shown the efficiency of our control system to maintain a reliable signal connection while minimising the use of antenna and reflector strips. Our system is the first proposal that maximises THz signal-to-noise ratio (SNR) through such a dynamic and robust control system, which integrates image processing of a room with base station configuration.

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Robust and Secure Wireless Communications via Intelligent Reflecting Surfaces

Abstract: If it is the author's pre-published version, changes introduced as a result of publishing processes such as copy-editing and formatting may not be reflected in this document. For a definitive version of this work, please refer to the published version.

Cited by 650 publications

References 44 publications

Robust Beamforming Design for Intelligent Reflecting Surface Aided MISO Communication Systems

Robust Beamforming Design for Intelligent Reflecting Surface Aided MISO Communication Systems

Secure Wireless Transmission for Intelligent Reflecting Surface-Aided Millimeter-Wave Systems

Digital Twin for Metasurface Reflector Management in 6G Terahertz Communications

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