A Novel SCA-Based Method for Beamforming Optimization in IRS/RIS-Assisted MU-MISO Downlink

• Published in: IEEE wireless communications letters Vol. 12; no. 2; pp. 297 - 301
• Main Authors: Kumar, Vaibhav, Zhang, Rui, Renzo, Marco Di, Tran, Le-Nam
• Format: Journal Article
• Language: English
• Published: Piscataway IEEE 01.02.2023; The Institute of Electrical and Electronics Engineers, Inc. (IEEE); IEEE comsoc
• Subjects: Beamforming; Benchmark testing; Benchmarks; Communications systems; Complexity theory; Downlink; Downlinking; Engineering Sciences; Intelligent reflecting surface; Interference; Iterative methods; MISO (control systems); MU-MISO; Optimization; Quality of service; reconfigurable intelligent surfaces; second-order cone programming; Signal and Image processing; Signal to noise ratio; successive convex approximation; reconfigurable intelligent surfaces; second-order cone programming; Intelligent reflecting surface; MU-MISO; successive convex approximation
• ISSN: 2162-2337; 2162-2345
• DOI: 10.1109/LWC.2022.3224316

In this letter, we consider the fundamental problem of jointly designing the transmit beamformers and the phase-shifts of the intelligent reflecting surface (IRS)/reconfigurable intelligent surface (RIS) to minimize the transmit power, subject to quality-of-service constraints at individual users in an IRS-assisted multiuser multiple-input single-output downlink communication system. In particular, we propose a new successive convex approximation based second-order cone programming approach in which all the optimization variables are simultaneously updated in each iteration. Our proposed scheme achieves superior performance compared to state-of-the-art benchmark solutions. In addition, the complexity of the proposed scheme is <inline-formula> <tex-math notation="LaTeX">O(N_{\mathrm {s}}^{3.5}) </tex-math></inline-formula>, while that of state-of-the-art benchmark schemes is <inline-formula> <tex-math notation="LaTeX">O(N_{\mathrm {s}}^{7}) </tex-math></inline-formula>, where <inline-formula> <tex-math notation="LaTeX">N_{\mathrm {s}} </tex-math></inline-formula> denotes the number of reflecting elements at the IRS.