Multicell MIMO Communications Relying on Intelligent Reflecting Surfaces

By Cunhua Pan, Hong Ren, Kezhi Wang, Wei Xu, Maged Elkashlan, Arumgam Nallanathan, Lajos Hanzo. IEEE Transactions on Wireless Communications, 2019

1,056 citations recorded by the source corpus.

Intelligent reflecting surfaces (IRSs) constitute a disruptive wireless communication technique capable of creating a controllable propagation environment. In this paper, we propose to invoke an IRS at the cell boundary of multiple cells to assist the downlink transmission to cell-edge users, whilst mitigating the inter-cell interference, which is a crucial issue in multicell communication systems. We aim for maximizing the weighted sum rate (WSR) of all users through jointly optimizing the active precoding matrices at the base stations (BSs) and the phase shifts at the IRS subject to each BS’s power constraint and unit modulus constraint. Both the BSs and the users are equipped with multiple antennas, which enhances the spectral efficiency by exploiting the spatial multiplexing gain. Due to the non-convexity of the problem, we first reformulate it into an equivalent one, which is solved by using the block coordinate descent (BCD) algorithm, where the precoding matrices and phase shifts are alternately optimized. The optimal precoding matrices can be obtained in closed form, when fixing the phase shifts. A pair of efficient algorithms are proposed for solving the phase shift optimization problem, namely the Majorization-Minimization (MM) Algorithm and the Complex Circle Manifold (CCM) Method. Both algorithms are guaranteed to converge to at least locally optimal solutions. We also extend the proposed algorithms to the more general multiple-IRS and network MIMO scenarios. Finally, our simulation results confirm the advantages of introducing IRSs in enhancing the cell-edge user performance.

Subfields: Aerospace Engineering, Electrical and Electronic Engineering

View Paper: https://www.semanticscholar.org/paper/7513dcbf6f9164dd2b1f5b3febeec23b51c05a26

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Citations in the corpus

A Framework of Robust Transmission Design for IRS-Aided MISO Communications With Imperfect Cascaded Channels (2020, methodology): “It is assumed that the phase shifts of the IRS are calculated by the BS and then fed back to the IRS controller through dedicated feedback channels [4], [5].”
A Joint Precoding Framework for Wideband Reconfigurable Intelligent Surface-Aided Cell-Free Network (2020, methodology): “This simplified subproblem P̂passive is similar to those in [19], [38].”
Reconfigurable Intelligent Surfaces: Principles and Opportunities (2020, background): “Additionally, current research contributions mainly consider the performance optimization for both single-user and multi-user scenarios by optimizing the phase shift and/or pre-coding solutions of the RIS-enhanced system [6], [18], [95], [133], [134].”
Channel Estimation and Passive Beamforming for Intelligent Reflecting Surface: Discrete Phase Shift and Progressive Refinement (2019, neutral): “multiplexing (OFDM) [14], MIMO [15], [16], non-orthogonal multiple access (NOMA) [17]–[20], physical-layer security”
Intelligent Reflecting Surface Aided Multigroup Multicast MISO Communication Systems (2019, background): “considered the weighted sum rate maximization problems in multicell MIMO communications [5], simultaneous wireless information and power transfer (SWIPT) aided systems [6], artificial-noise-aided secureMIMO communications [9], all demonstrating the significant performance gains achieved by deploying”
Reconfigurable Intelligent Surface Assisted Multiuser MISO Systems Exploiting Deep Reinforcement Learning (2020, methodology): “In [26], the weighted sum rate of all users in multi-cell MIMO settings were investigated, through jointly optimizing the transmit beamforming and the phase shifts subject to each BS’s power constraint and unit modulus constraint.”
Joint Transmit Waveform and Passive Beamforming Design for RIS-Aided DFRC Systems (2021, background): “Motivated by the above, the applications of RIS in various wireless communication scenarios have been widely studied, including but not limited to the designs for maximizing spectral efficiency [10], [11], sum-rate [12]-[14], energy efficiency [15], [16], and minimizing transmit power [17], [18], et”
Double-IRS Assisted Multi-User MIMO: Cooperative Passive Beamforming Design (2020, neutral): “, orthogonal frequency division multiplexing (OFDM) [5]–[8], multi-antenna communication [?], [9], [10], non-orthogonal multiple access (NOMA) [12]–[14], etc.”
Stacked Intelligent Metasurfaces for Efficient Holographic MIMO Communications in 6G (2023, neutral): “service (QoS) [18], [19], [20] in RIS-assisted communication systems, etc.”
Smart Radio Environments Empowered by Reconfigurable Intelligent Surfaces: How it Works, State of Research, and Road Ahead (2020, background): “In [149], the authors study the downlink of a MIMO multicell system, wherein an RIS is deployed at the boundary between multiple cells.”
Toward Smart Wireless Communications via Intelligent Reflecting Surfaces: A Contemporary Survey (2019, methodology): “To mitigate inter-cell interference, the authors in [141] deploy the IRS at the cell boundary of a multi-cell system to assist the downlink MIMO transmissions to cell-edge users.”
Beam Focusing for Near-Field Multi-User MIMO Communications (2021, methodology): “, using the bisection method [27], [35].”
Modeling and Architecture Design of Reconfigurable Intelligent Surfaces Using Scattering Parameter Network Analysis (2020, methodology): “Previous work on multi-user [8] and multi-cell scenarios [10] only use RIS with the single connected architecture to minimize the transmit power and maximize the weight sum rate, respectively.”
Reconfigurable Intelligent Surfaces for 6G Systems: Principles, Applications, and Research Directions (2021, neutral): “Explicitly, in [7], an iterative algorithm was proposed for”
Intelligent Reflecting Surface-Aided Wireless Communications: A Tutorial (2020, background): “In [83], the authors considered a simplified setup with one IRS serving two adjacent cells and showed that the IRS should be deployed at the intersection of their edges to maximally benefit both cells.”