Intelligent Reflecting Surface-Assisted Millimeter Wave Communications: Joint Active and Passive Precoding Design

By Peilan Wang, Jun Fang, Xiaojun Yuan, Zhi Chen, Hongbin Li. IEEE Transactions on Vehicular Technology, 2019

486 citations recorded by the source corpus.

Millimeter wave (MmWave) communications is capable of supporting multi-gigabit wireless access thanks to its abundant spectrum resource. However, severe path loss and high directivity make it vulnerable to blockage events, which can be frequent in indoor and dense urban environments. To address this issue, in this paper, we introduce intelligent reflecting surface (IRS) as a new technology to provide effective reflected paths to enhance the coverage of mmWave signals. In this framework, we study joint active and passive precoding design for IRS-assisted mmWave systems, where multiple IRSs are deployed to assist the data transmission from a base station (BS) to a single-antenna receiver. Our objective is to maximize the received signal power by jointly optimizing the BS's transmit precoding vector and IRSs’ phase shift coefficients. Although such an optimization problem is generally non-convex, we show that, by exploiting some important characteristics of mmWave channels, an optimal closed-form solution can be derived for the single IRS case and a near-optimal analytical solution can be obtained for the multi-IRS case. Our analysis reveals that the received signal power increases quadratically with the number of reflecting elements for both the single IRS and multi-IRS cases. Simulation results are included to verify the optimality and near-optimality of our proposed solutions. Results also show that IRSs can help create effective virtual line-of-sight (LOS) paths and thus substantially improve robustness against blockages in mmWave communications.

Subfields: Aerospace Engineering, Electrical and Electronic Engineering

View Paper: https://www.semanticscholar.org/paper/1ec46fe606c170622005a4619580da329b0b8839

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Citations in the corpus

Reconfigurable Intelligent Surfaces for Wireless Communications: Principles, Challenges, and Opportunities (2020, background): “optimal, which can be solved analytically or formulated as a semidefinite program (SDP) [32], [33] in case of continuous phase shifts.”
Smart Radio Environments Empowered by Reconfigurable Intelligent Surfaces: How It Works, State of Research, and The Road Ahead (2020, background): “In [240], the authors study the application of RISs in order to overcome signal path-loss and blind spots in millimeter-wave systems.”
Compressed Channel Estimation for Intelligent Reflecting Surface-Assisted Millimeter Wave Systems (2020, background): “Recently, IRS was introduced to establish robust mmWave connections when the line-of-sight (LOS) link is blocked by obstructions [5], [6].”
Intelligent Reflecting Surface-Aided Wireless Communications: A Tutorial (2020, background): “achieving both high spectral and energy efficiencies [20], [77], [179]–[183].”
Joint Active and Passive Beamforming Optimization for Intelligent Reflecting Surface Assisted SWIPT Under QoS Constraints (2019, background): “, physical layer security [10]–[13], non-orthogonal multiple access [15], [16], [20], and millimeter wave (mmWave) communications [21], [22].”
A Joint Precoding Framework for Wideband Reconfigurable Intelligent Surface-Aided Cell-Free Network (2020, methodology): “the density of BSs and users in cell-free network is high [9] and the number of RIS elements is usually large [18], we can reasonably assume that BMPK U and RN U .”
Physics-Based Modeling and Scalable Optimization of Large Intelligent Reflecting Surfaces (2020, background): “The IRS is conﬁgured by optimizing the β q which leads to non-convex optimization problems due to the unit-modulus constraint imposed by | e jβ q | = 1 , see [6], [7], [11]–[15] for different approaches to cope with this non-convex constraint.”
Smart Radio Environments Empowered by Reconfigurable Intelligent Surfaces: How it Works, State of Research, and Road Ahead (2020, background): “In [249], the authors analyze a single-user downlink”
Toward Smart Wireless Communications via Intelligent Reflecting Surfaces: A Contemporary Survey (2019, methodology): “We note that all aforementioned research works in [118], [119], [121]–[124], [126] rely on the ideally designed IRS with inﬁnite phase resolution, i.e., the phase shift of each scattering element can be fully controllable.”
An Overview of Signal Processing Techniques for RIS/IRS-Aided Wireless Systems (2021, unknown): “…performance gains provided by introducing an RIS in various wireless applications have been investigated, such as mmWave/terahertz systems [84], [89], [142]–[145], multicell systems [101], [146], [147], physical layer security systems [83], [87], [88], [97], [98], [148], [149], simultaneous…”