Intelligent Reflecting Surface Enhanced Wireless Network: Joint Active and Passive Beamforming Design

By Qingqing Wu, Rui Zhang. Global Communications Conference, 2018

815 citations recorded by the source corpus.

Intelligent reflecting surface (IRS) is envisioned to have abundant applications in future wireless networks by smartly reconfiguring the signal propagation for performance enhance- ment. Specifically, an IRS consists of a large number of low- cost passive elements each reflecting the incident signal with a certain phase shift to collaboratively achieve beamforming and suppress interference at one or more designated receivers. In this paper, we study an IRS-enhanced point-to-point multiple- input single-output (MISO) wireless system where one IRS is deployed to assist in the communication from a multi-antenna access point (AP) to a single-antenna user. As a result, the user simultaneously receives the signal sent directly from the AP as well as that reflected by the IRS. We aim to maximize the total received signal power at the user by jointly optimizing the (active) transmit beamforming at the AP and (passive) reflect beamforming by the phase shifters at the IRS. We first propose a centralized algorithm based on the technique of semidefinite relaxation (SDR) by assuming the global channel state information (CSI) available at the IRS. Since the centralized implementation requires excessive channel estimation and signal exchange overheads, we further propose a low-complexity distributed algorithm where the AP and IRS independently adjust the transmit beamforming and the phase shifts in an alternating manner until the convergence is reached. Simulation results show that significant performance gains can be achieved by the proposed algorithms as compared to benchmark schemes. Moreover, it is verified that the IRS is able to drastically enhance the link quality and/or coverage over the conventional setup without the IRS.

Subfields: Aerospace Engineering, Electrical and Electronic Engineering

View Paper: https://www.semanticscholar.org/paper/50910f816336a02b4182468d1cc8c42e8189f24c

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Citations in the corpus

Channel Estimation and Low-complexity Beamforming Design for Passive Intelligent Surface Assisted MISO Wireless Energy Transfer (2019, methodology): “Also, their requirements are very different from those of the multiantenna amplify-and-forward relays [1, 4], where active transceiver units are involved.”
Intelligent Reflecting Surface-Assisted Millimeter Wave Communications: Joint Active and Passive Precoding Design (2019, background): “Such a problem was studied in a single-user scenario, with the objective of maximizing the receive signal power [14].”
Weighted Sum-Rate Maximization for Reconfigurable Intelligent Surface Aided Wireless Networks (2019, methodology): “In [21] and [22], the transmit power of the AP is minimized by decomposing the joint optimization problem into two subproblems: one is the conventional power-minimization problem in MIMO system, and the other is for the RIS phase vector optimization.”
Enabling Secure Wireless Communications via Intelligent Reflecting Surfaces (2019, methodology): “A point-to-point multiple-input singleoutput (MISO) system was investigated in [6], [7], where the IRS is implemented with continuous and discrete phase shifters, respectively.”
Reconfigurable Intelligent Surfaces for Wireless Communications: Principles, Challenges, and Opportunities (2020, methodology): “If the relevant channels are known, then co-phasing all paths is optimal, which can be solved analytically or formulated as a semideﬁnite program (SDP) [32], [33] in case of continuous phase shifts.”
Secrecy Rate Maximization for Intelligent Reflecting Surface Assisted Multi-Antenna Communications (2019, background): “The problem is quite challenging even when the eavesdropper has a single antenna, which cannot be straightforwardly solved with the techniques developed in [9]–[14].”
An Optimal Channel Estimation Scheme for Intelligent Reflecting Surfaces Based on a Minimum Variance Unbiased Estimator (2019, methodology): “This desired control can be achieved by introducing Intelligent Reflecting Surfaces (IRSs) [1], where incoming signals can be reflected with passive programmable units—sometimes referred to as passive beamforming [2].”
Intelligent Reflecting Surface Enhanced Wireless Network via Joint Active and Passive Beamforming (2018, background): “This article was presented in part at the IEEE GLOBECOM 2018 [1].”
Intelligent Reflecting Surface: A Programmable Wireless Environment for Physical Layer Security (2019, methodology): “The reflecting coefficient channel of the IRS [16] is given by 2 = diag(θ ) ∈ CL×L with θ = [θ1, θ2, · · · , θL] ∈ CL×1 and θl ∈ 8 for 1 ≤ l ≤ L, where diag(·) denotes a diagonal matrix whose diagonal elements are given by the corresponding vector and 8 denotes the set of reflecting coefficients of ”
Joint Transmit Waveform and Passive Beamforming Design for RIS-Aided DFRC Systems (2021, background): “The optimization problems for initializing φ and x have been extensively investigated in the literature [17], [36], and the details are omitted here due to space limitations.”
Wireless Communications Through Reconfigurable Intelligent Surfaces (2019, background): “Th problem of joint active and passive beamformer design is investigated in [75] and [76].”
Reconfigurable Intelligent Surfaces vs. Relaying: Differences, Similarities, and Performance Comparison (2019, background): “2(b)), since the distance from the feeder to the RIS can be ignored, or when they are deployed sufficiently close to the receiver for local coverage enhancement [6], [7].”
Toward Smart Wireless Communications via Intelligent Reflecting Surfaces: A Contemporary Survey (2019, methodology): “The simulation results demonstrate signiﬁcant performance gain over the conventional SDR-based algorithms, e.g., [116], [124], [144], [151].”
Channel Estimation for Intelligent Reflecting Surface Assisted Multiuser Communications: Framework, Algorithms, and Analysis (2019, background): “It can be shown that the number of channel coefficients involved for designing the IRS reflection coefficients based on the algorithms proposed in [6], [7] is KMN +KM .”
Reconfigurable Intelligent Surfaces for Energy Efficiency in Wireless Communication (2018, background): “The presented experiments demonstrated various controllable electromagnetic phenomena, including anomalous reﬂection and diffusion, as well as beamforming [20], [38].”
Intelligent Reflecting Surface-Assisted Multi-User MISO Communication: Channel Estimation and Beamforming Design (2020, methodology): “The AO technique has been utilized in [13] to solve the transmit power minimization problem and in [15] for energy efﬁciency maximization problem.”
Multi-Hop RIS-Empowered Terahertz Communications: A DRL-Based Hybrid Beamforming Design (2021, methodology): “…approximation methods that are proposed based on the alternating method to ﬁnd the sub-optimal solutions for single hop RIS-based system, e.g., [32]–[38], they are difﬁcult to work for the multi-hop scenario, especially we do not know how many RIS hops the transmitted signal experienced to…”
Beamforming Optimization for Intelligent Reflecting Surface with Discrete Phase Shifts (2018, methodology): “, 0 ≤ θn < 2π,∀n (see [3] for an algorithm to solve this problem), and then quantizing the continuous phase shifts obtained to their nearest points in F similarly as (9).”
Toward Massive MIMO 2.0: Understanding Spatial Correlation, Interference Suppression, and Pilot Contamination (2019, background): “A different but related concept is an intelligent reflecting surface [68], which is not actively transmitting power but when illuminated by the signal from a BS or UE, it can reconfigure its reflective properties to form narrow beams with desired properties.”