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Degree of Freedom Analysis for Holographic MIMO Based on a Mutual-Coupling-Compliant Channel Model

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ZTE Communications 2024年

作者： SUN Yunqi jian mengnan YANG Jun ZHAO Yajun CHEN Yijian State Key Laboratory of Mobile Network and Mobile Multimedia Technology ZTE Corporation

Degree of freedom (DOF) is a key indicator for spatial multiplexing layers of a wireless channel. Traditionally， the channel of a multiple-input multiple-output (MIMO) half-wavelength dipole array has a DOF that equals the antenna number. However， recent studies suggest that the DOF could be less than the antenna number when strong mutual coupling is considered. We utilize a mutual-coupling-compliant channel model to investigate the DOF of the holographic MIMO (HMIMO) channel and give a upper bound of the DOF with strong mutual coupling. Our numerical simulations demonstrate that a dense array can support more DOF per unit aperture as compared to a half-wavelength MIMO system.

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Integrated sensing and communication based outdoor multi-target detection,tracking,and localization in practical 5G Networks

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Intelligent and Converged Networks 2023年第3期4卷 261-272页

作者： Ruiqi Liu mengnan jian Dawei Chen Xu Lin Yichao Cheng Wei Cheng Shijun Chen the Wireless Research Institute ZTE CorporationBeijing 100029China the State Key Laboratory of Mobile Network and Mobile Multimedia Technology Shenzhen 518055China

The 6th generation(6G)wireless networks will likely to support a variety of capabilities beyond communication,such as sensing and localization,through the use of communication networks empowered by advanced technologies.Integrated sensing and communication(ISAC)has been recognized as a critical technology as well as a usage scenario for 6G,as widely agreed by leading global standardization bodies.ISAC utilizes communication infrastructure and devices to provide the capability of sensing the environment with high resolution,as well as tracking and localizing moving objects nearby.Meeting both the requirements for communication and sensing simultaneously,ISAC-based approaches celebrate the advantages of higher spectral and energy efficiency compared to two separate systems to serve two purposes,and potentially lower costs and easy deployment.A key step towards the standardization and commercialization of ISAC is to carry out comprehensive field trials in practical networks,such as the 5th generation(5G)networks,to demonstrate its true capacities in practical scenarios.In this paper,an ISAC-based outdoor multi-target detection,tracking and localization approach is proposed and validated in 5G networks.The proposed system comprises of 5G base stations(BSs)which serve nearby mobile users normally,while accomplishing the task of detecting,tracking,and localizing drones,vehicles,and pedestrians simultaneously.Comprehensive trial results demonstrate the relatively high accuracy of the proposed method in practical outdoor environment when tracking and localizing single targets and multiple targets.

关键词： integrated sensing and communication prototype 5G track detection localization trial

Reconfigurable intelligent surfaces for wireless communications:Overview of hardware designs,channel models,and estimation techniques

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Intelligent and Converged Networks 2022年第1期3卷 1-32页

作者： mengnan jian George C.Alexandropoulos Ertugrul Basar Chongwen Huang Ruiqi Liu Yuanwei Liu Chau Yuen the Wireless Research Institute ZTE CorporationBeijing 100029China the State Key Laboratory of Mobile Network and Mobile Multimedia Technology Shenzhen 518055China Department of Informatics and Telecommunications National and Kapodistrian University of AthensAthens 15784Greece Communications Research and Innovation Laboratory(CoreLab) Department of Electrical and Electronics EngineeringKoçUniversityIstanbul 34450Turkey College of Information Science and Electronic Engineering Zhejiang UniversityHangzhou 310027China School of Electronic Engineering and Computer Science Queen Mary University of LondonLondonE14NSUK. the Engineering Product Development(EPD)Pillar Singapore University of Technology and DesignSingapore 487372Singapore

The demanding objectives for the future sixth generation(6G)of wireless communication networks have spurred recent research efforts on novel materials and radio-frequency front-end architectures for wireless connectivity,as well as revolutionary communication and computing paradigms.Among the pioneering candidate technologies for 6G belong the reconfigurable intelligent surfaces(RISs),which are artificial planar structures with integrated electronic circuits that can be programmed to manipulate the incoming electromagnetic field in a wide variety of functionalities.Incorporating RISs in wireless networks have been recently advocated as a revolutionary means to transform any wireless signal propagation environment to a dynamically programmable one,intended for various networking objectives,such as coverage extension and capacity boosting,spatiotemporal focusing with benefits in energy efficiency and secrecy,and low electromagnetic field exposure.Motivated by the recent increasing interests in the field of RISs and the consequent pioneering concept of the RIS-enabled smart wireless environments,in this paper,we overview and taxonomize the latest advances in RIS hardware architectures as well as the most recent developments in the modeling of RIS unit elements and RIS-empowered wireless signal propagation.We also present a thorough overview of the channel estimation approaches for RIS-empowered communications systems,which constitute a prerequisite step for the optimized incorporation of RISs in future wireless networks.Finally,we discuss the relevance of the RIS technology in the latest wireless communication standards,and highlight the current and future standardization activities for the RIS technology and the consequent RIS-empowered wireless networking approaches.

关键词： reconfigurable intelligent surfaces beyond 5G 6G channel modeling hardware architecture channel estimation smart wireless environment standardization

AIRIS:Artificial Intelligence Enhanced Signal Processing in Reconfigurable Intelligent Surface Communications

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China Communications 2021年第7期18卷 158-171页

作者： Shun Zhang Muye Li mengnan jian Yajun Zhao Feifei Gao State Key Laboratory of Integrated Services Networks Xidian UniversityXi’an 710071China Algorithm Department of Wireless Product R&D Institute ZTE CorporationBeijing 100029China Institute for Artificial Intelligence Tsinghua University(THUAI)State Key Lab of Intelligent Technologies and SystemsTsinghua UniversityBeijing National Research Center for Information Science and Technology(BNRist)Department of AutomationTsinghua University Beijing100084China

Reconfigurable intelligent surface(RIS)is an emerging meta-surface that can provide additional communications links through reflecting the signals,and has been recognized as a strong candidate of 6G mobile communications systems.Meanwhile,it has been recently admitted that implementing artificial intelligence(AI)into RIS communications will extensively benefit the reconfiguration capacity and enhance the robustness to complicated transmission environments.Besides the conventional model-driven approaches,AI can also deal with the existing signal processing problems in a data-driven manner via digging the inherent characteristic from the real data.Hence,AI is particularly suitable for the signal processing problems over RIS networks under unideal scenarios like modeling mismatching,insufficient resource,hardware impairment,as well as dynamical transmissions.As one of the earliest survey papers,we will introduce the merging of AI and RIS,called AIRIS,over various signal processing topics,including environmental sensing,channel acquisition,beamforming design,and resource scheduling,etc.We will also discuss the challenges of AIRIS and present some interesting future directions.

关键词： reconfigurable intelligent surface artifi-cial intelligence deep learning deep reinforcement learning signal processing

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智能超表面近场通信的机遇与挑战

无线电通信技术 2024年第2期50卷 253-262页

作者：菅梦楠赵亚军中兴通讯股份有限公司北京100192 移动网络和移动多媒体技术国家重点实验室广东深圳518055

实现无线环境的智能可控是无线通信领域研究的热门课题之一。作为6G的关键技术之一,智能超表面(Reconfigurable Intelligent Surface, RIS)被认为是一种革命性的电磁环境调控技术。RIS以绿色、低成本的方式显著提升网络性能,通过对发射... 详细信息

实现无线环境的智能可控是无线通信领域研究的热门课题之一。作为6G的关键技术之一,智能超表面(Reconfigurable Intelligent Surface, RIS)被认为是一种革命性的电磁环境调控技术。RIS以绿色、低成本的方式显著提升网络性能,通过对发射机和接收机以及传播环境的联合优化,重新定义无线系统的传播范式,构建智能可控的无线传播环境。RIS通常依赖于无源被动调控机制,但这种机制带来乘性路径损耗问题,超大规模调控单元的部署十分必要。随着阵列尺寸的扩大以及频率的提高,传统的平面波假设不再适用,近场传输不可避免。为了更精确地刻画RIS近场传输,需要研究近场球面波的传输模型及其在辐射近场区域的影响。深入分析RIS辅助的近场无线通信系统的信道模型,针对性地设计了适应性预编码方案和传输策略,旨在充分利用RIS辅助近场通信的潜在优势,提升整个无线通信系统的性能和效率。

关键词： 6G 智能超表面近场通信分数傅里叶变换预编码设计

轨道角动量技术研究进展及其在5G-A和6G中的应用前景分析

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信息通信技术 2024年第1期18卷 7-15页

作者：王喜瑜孙韵淇菅梦楠杨军陈艺戬移动网络和移动通讯多媒体技术国家重点实验室深圳518055 中兴通讯股份有限公司深圳518055

近年来,5G的建设取得了丰硕的成果。以3GPP为首的标准组织正在积极开展5G第二阶段(5G Advanced,5G-A)以及6G的候选技术及标准工作。电磁波的轨道角动量技术(Orbital Angular Momentum,OAM)是IMT-2030推进组在6G布局的重要研究方向,以其... 详细信息

近年来,5G的建设取得了丰硕的成果。以3GPP为首的标准组织正在积极开展5G第二阶段(5G Advanced,5G-A)以及6G的候选技术及标准工作。电磁波的轨道角动量技术(Orbital Angular Momentum,OAM)是IMT-2030推进组在6G布局的重要研究方向,以其优异的理论容量性能在学术界和产业界获得了大量关注。文章总结OAM技术应用于通信的优势,例如可支持视距超多流并行传输,提升通信物理层安全,与智能超表面(Reconfigurable Intelligence Surface,RIS)技术结合赋能等,提出在大数据和工业互联网等应用场景下,利用OAM技术建立的超大规模无线数据中心将助力实现数据要素深度参与工业生产,提升全产业链生产效率,推动6G与产业协同发展。

关键词：无线通信轨道角动量智能超表面物理层安全

RIS:Spatial-Wideband Effect Analysis and Off-Grid Channel Estimation

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ZTE Communications 2022年第1期20卷 57-62页

作者： jian mengnan ZHANG Nan CHEN Yijian State Key Laboratory of Mobile Network and Mobile Multimedia Technology Shenzhen 518055China Algorithm Department Wireless Product R&D InstituteZTE Corpo-rationShenzhen 518057China

As a critical candidate technology for 5G-advanced and 6G,reconfigurable intelligent surfaces(RIS)have received extensive atten-tion from academia and industry.RIS has the promising features of passiveness,reconfigurable ability,and low cost.RIS channel estimation faces the challenges of high matrix dimension,passive estimation,and spatial-wideband effect.In this article,we analyze the impact of the spatial-wideband effect on the RIS channel to account for the propagation delay across RIS elements and estimate sparse channel parameters such as angle and gain through a super-resolution compressive sensing(CS)algorithm.The simulation results explore the influence of the spatial-wideband effect on the RIS channel and verify the effectiveness of the proposed algorithm.

关键词： RIS channel estimation spatial-wideband effect compressed sensing

Emergent Geometry of KP Hierarchy

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Acta Mathematica Sinica,English Series 2024年第1期40卷 3-25页

作者： jian ZHOU Department of Mathematical Sciences Tsinghua UniversityBeijng 100084P.R.China

We explain how to construct a quantum deformation of a spectral curve associated to a tau-function of the KP hierarchy.This construction is applied to Witten-Kontsevich tau-function to give a natural explanation of so... 详细信息

关键词： KP hierarchy tau-functions spectral curves

Development in oxide metallurgy for improving the weldability of high -strength low-alloy steel-Combined deoxidizers and microalloying elements

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International Journal of Minerals,Metallurgy and Materials 2024年第6期31卷 1263-1284页

作者： Tingting Li jian Yang State Key Laboratory of Advanced Special Steel School of Materials Science and EngineeringShanghai UniversityShanghai 200444China

The mechanisms of oxide metallurgy include inducing the formation of intragranular acicular ferrite(IAF)using micron-sized inclusions and restricting the growth of prior austenite grains(PAGs)by nanosized particles during welding.The chaotically oriented IAF and refined PAGs inhibit crack initiation and propagation in the steel,resulting in high impact toughness.This work summarizes the com-bined effect of deoxidizers and alloying elements,with the aim to provide a new perspective for the research and practice related to im-proving the impact toughness of the heat affected zone(HAZ)during the high heat input welding.Ti complex deoxidation with other strong deoxidants,such as Mg,Ca,Zr,and rare earth metals(REMs),can improve the toughness of the heat-affected zone(HAZ)by re-fining PAGs or increasing IAF contents.However,it is difficult to identify the specific phase responsible for IAF nucleation because ef-fective inclusions formed by complex deoxidation are usually multiphase.Increasing alloying elements,such as C,Si,Al,Nb,or Cr,con-tents can impair HAZ toughness.A high C content typically increases the number of coarse carbides and decreases the potency of IAF formation.Si,Cr,or Al addition leads to the formation of undesirable microstructures.Nb reduces the high-temperature stability of the precipitates.Mo,V,and B can enhance HAZ toughness.Mo-containing precipitates present good thermal stability.VN or V(C,N)is ef-fective in promoting IAF nucleation due to its good coherent crystallographic relationship with ferrite.The formation of the B-depleted zone around the inclusion promotes IAF formation.The interactions between alloying elements are complex,and the effect of adding dif-ferent alloying elements remains to be evaluated.In the future,the interactions between various alloying elements and their effects on ox-ide metallurgy,as well as the calculation of the nucleation effects of effective inclusions using first principles calculations will become the focus of oxide metallurgy.

关键词： oxide metallurgy technology heat affected zone high-strength low-alloy steel intragranular acicular ferrite microalloying element