Efficient Beamforming for Discrete SIM-Aided Multiuser Systems Under Statistical CSI

Fuente: arXiv
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Main Authors: Jiao, Yuhui, Zhang, Qian, Cheng, Xuejun, Li, Yunxiao, Zhao, Yufei, Liu, Ju, Guan, Yong Liang
Format: Preprint
Published: 2026
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author Jiao, Yuhui
Zhang, Qian
Cheng, Xuejun
Li, Yunxiao
Zhao, Yufei
Liu, Ju
Guan, Yong Liang
author_facet Jiao, Yuhui
Zhang, Qian
Cheng, Xuejun
Li, Yunxiao
Zhao, Yufei
Liu, Ju
Guan, Yong Liang
contents Stacked Intelligent Metasurfaces (SIM) have emerged as a revolutionary architecture for next-generation wireless communications, offering wave-domain signal processing capabilities with significantly reduced hardware complexity compared to conventional systems. However, most existing SIM research assumes continuous phase shifts and perfect instantaneous channel state information (CSI), which are impractical due to hardware discrete phase shift constraints and prohibitive pilot overhead. This paper presents a joint power allocation and discrete phase shift optimization framework for SIM-aided multiuser multiple-input single-output(MISO) downlink systems under statistical CSI. We formulate the achievable sum rate maximization problem considering practical discrete phase constraints and derive a closed-form expression for the average achievable rate under statistical CSI. To tackle the resulting non-convex optimization problem, we decouple the problem by using the weighted minimum mean square error (WMMSE) algorithm and alternating optimization (AO). Subsequently, we utilize the Lagrangian multiplier method and alternating direction method of multipliers (ADMM) to obtain closed-form iterative solutions. Our simulations demonstrate that the proposed algorithm reduces computational complexity by a factor of 50 compared to semi-definite relaxation (SDR) methods, , while maintaining over 85% of the continuous phase shift performance with only 1-bit quantization, highlighting its feasibility for low-cost hardware systems.
format Preprint
id arxiv_https___arxiv_org_abs_2601_14803
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Efficient Beamforming for Discrete SIM-Aided Multiuser Systems Under Statistical CSI
Jiao, Yuhui
Zhang, Qian
Cheng, Xuejun
Li, Yunxiao
Zhao, Yufei
Liu, Ju
Guan, Yong Liang
Information Theory
Stacked Intelligent Metasurfaces (SIM) have emerged as a revolutionary architecture for next-generation wireless communications, offering wave-domain signal processing capabilities with significantly reduced hardware complexity compared to conventional systems. However, most existing SIM research assumes continuous phase shifts and perfect instantaneous channel state information (CSI), which are impractical due to hardware discrete phase shift constraints and prohibitive pilot overhead. This paper presents a joint power allocation and discrete phase shift optimization framework for SIM-aided multiuser multiple-input single-output(MISO) downlink systems under statistical CSI. We formulate the achievable sum rate maximization problem considering practical discrete phase constraints and derive a closed-form expression for the average achievable rate under statistical CSI. To tackle the resulting non-convex optimization problem, we decouple the problem by using the weighted minimum mean square error (WMMSE) algorithm and alternating optimization (AO). Subsequently, we utilize the Lagrangian multiplier method and alternating direction method of multipliers (ADMM) to obtain closed-form iterative solutions. Our simulations demonstrate that the proposed algorithm reduces computational complexity by a factor of 50 compared to semi-definite relaxation (SDR) methods, , while maintaining over 85% of the continuous phase shift performance with only 1-bit quantization, highlighting its feasibility for low-cost hardware systems.
title Efficient Beamforming for Discrete SIM-Aided Multiuser Systems Under Statistical CSI
topic Information Theory
url https://arxiv.org/abs/2601.14803