Configuring Intelligent Reflecting Surface With Performance Guarantees: Optimal Beamforming

Zhang, Yaowen; Shen, Kaiming; Ren, Shuyi; Li, Xin; Chen, Xin; Luo, Zhi-Quan

doi:10.1109/jstsp.2022.3176479

Cited by 30 publications

(41 citation statements)

References 53 publications

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“…Besides the exhaustive-search method, we also consider a baseline scheme, namely, the activation of all IRS elements (i.e., x = 1 L ). 7 First of all, Fig. 1 shows the worst-case EE versus the number of IRS elements.…”

Section: (And Assumption 1 As Well According To Proposition 1)mentioning

confidence: 99%

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Global Optimization of Energy Efficiency in IRS-Aided Communication Systems via Robust IRS-Element Activation

Efrem¹,

Krikidis²

2022

Preprint

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In this paper, we study an intelligent reflecting surface (IRS) assisted communication system with single-antenna transmitter and receiver, under imperfect channel state information (CSI). More specifically, we deal with the robust selection of binary (on/off) states of the IRS elements in order to maximize the worst-case energy efficiency (EE), given a bounded CSI uncertainty, while satisfying a minimum signalto-noise ratio (SNR). The IRS phase shifts are adjusted so as to maximize the ideal SNR (i.e., without CSI error), based only on the estimated channels. First, we derive a closed-form expression of the worst-case SNR, and then formulate the robust (discrete) optimization problem. Moreover, we design and analyze a dynamic programming (DP) algorithm that is theoretically guaranteed to achieve the global maximum with polynomial complexity O(L log L), where L is the number of IRS elements. Finally, numerical simulations confirm the theoretical results. In particular, the proposed algorithm shows identical performance with the exhaustive search, and significantly outperforms a baseline scheme, namely, the activation of all IRS elements.

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Section: (And Assumption 1 As Well According To Proposition 1)mentioning

confidence: 99%

“…Energy efficiency (EE) optimization has been an attractive area of research in wireless networks [3], and more recently in IRS-aided communication systems [4]. Moreover, there has been a growing interest in active/passive-IRS beamforming to optimize the achievable sum-rate [5], signal-to-noise ratio (SNR) [6], [7], and transmit power [8].…”

Section: Introductionmentioning

confidence: 99%

Global Optimization of Energy Efficiency in IRS-Aided Communication Systems via Robust IRS-Element Activation

Efrem¹,

Krikidis²

2022

Preprint

View full text Add to dashboard Cite

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“…The proposed framework is also efficient for other models in maximizing SNR, e.g., [23], [27]. Exactly, optimization problems can be transformed into Quadratic form maximization problems are all well resoluble.…”

Section: Attentionmentioning

confidence: 99%

“…The main disadvantage of this heuristic strategy is the inherent quantization error, especially for extremely low resolution quantization schemes. It has recently been pointed out that this strategy can lead to an arbitrarily lousy performance in the worst-case scenario [23].…”

Section: Introductionmentioning

confidence: 99%

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Optimal Discrete Beamforming of Reconfigurable Intelligent Surface

Xiong¹,

Dong²,

Mi³

et al. 2022

Preprint

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Utilizing reconfigurable intelligent surfaces (RISs) for communication service usually leads to non-convex optimization problems. Existing methods either suffer from significant scalability issues or lead to local optima. This paper focuses on optimal beamforming in RIS-aided single input single output (SISO) communications. We formulate the discrete beamforming into a discrete product maximization problem, a fundamental yet unexplored problem. A highly efficient divide-and-sort (DaS) search framework is developed. The proposed approach is guaranteed to find global optima with linear search complexity, both in the number of discrete levels and the length of vectors. This approach is seen as particularly effective for large scale problems. Numerical and experimental studies about the effectiveness and speed of DaS are also presented. Extensive trails show that, for moderate resolution quantization, e.g., 4-bits and above, there seems to be no noticeable difference between continuous and discrete phase configuration.

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Real‐World Wireless Network Modeling and Optimization: From Model/Data‐Driven Perspective

Yang

Zhang

Ren

et al. 2022

Chinese J of Electronics

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With the rapid development of the fifthgeneration wireless communication systems, a profound revolution in terms of transmission capacity, energy efficiency, reliability, latency, and connectivity is highly expected to support a new batch of industries and applications. To achieve this goal, wireless networks are becoming extremely dynamic, heterogeneous, and complex. The modeling and optimization for the performance of realworld wireless networks are extremely challenging due to the difficulty to predict the network performance as a function of network parameters, and the prohibitively huge number of parameters to optimize. The conventional network modeling and optimization approaches rely on drive test, trial‐and‐error, and engineering experience, which are labor intensive, error‐prone, and far from optimal. On the other hand, while the research community has spent significant efforts in understanding the fundamental limits of radio channels and developing physical layer techniques to operate close to it, very little is known about the performance limits of wireless networks, where millions of radio channels interact with one another in complex manners. This paper reviews the very recent mathematical and learning based techniques for modeling and optimizing the performance of real‐world wireless networks in five aspects, including channel modeling, user demand and traffic modeling, throughput modeling and prediction, network parameter optimization, and IRS empowered performance optimization, and also presents the corresponding notable performance gains.

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Configuring Intelligent Reflecting Surface With Performance Guarantees: Optimal Beamforming

Cited by 30 publications

References 53 publications

Global Optimization of Energy Efficiency in IRS-Aided Communication Systems via Robust IRS-Element Activation

Global Optimization of Energy Efficiency in IRS-Aided Communication Systems via Robust IRS-Element Activation

Optimal Discrete Beamforming of Reconfigurable Intelligent Surface

Real‐World Wireless Network Modeling and Optimization: From Model/Data‐Driven Perspective

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