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Space-frequency-polarization-division multiplexed wireless communication system using anisotropic space-time-coding digital metasurface

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national science Review 2022年第11期9卷 149-160页

作者： Jun Chen Ke Xiangyu Chen Wankai Tang Ming Zheng Chen Lei Zhang Li Wang Jun Yan Dai Jin Yang Jun Wei Zhang Lijie Wu Qiang Cheng Shi Jin Tie Jun Cui State Key laboratory of Millimeter Waves Southeast University Institute of Electromagnetic Space Southeast University frontiers science center for mobile information communication and security Southeast University national mobile communications research laboratory Southeast University Southeast University Wuxi Campus

In the past few years, wireless communications based on digital coding metasurfaces have gained research interest owing to their simplified architectures and low cost. However, in most of the metasurface-based wireless systems, a single-polarization scenario is used, limiting the channel capacities. To solve the problem, multiplexing methods have been adopted, but the system complexity is inevitably increased. Here,a space-frequency-polarization-division multiplexed wireless communication system is proposed using an anisotropic space-time-coding digital metasurface. By separately designing time-varying control voltage sequences for differently oriented varactor diodes integrated on the metasurface, we achieve frequency-polarization-division multiplexed modulations. By further introducing different time-delay gradients to the control voltage sequences in two polarization directions, we successfully obtain space-frequency-polarization-division multiplexed modulations to realize a wireless communication system with a new architecture. The new communication system is designed with compact dual-polarized meta-elements, and can improve channel capacity and space utilization. Experimental results demonstrate the high-performance and real-time transmission capability of the proposed communication system,confirming its potential application in multiple-user collaborative wireless communications.

关键词： polarization-division multiplexing frequency-division multiplexing space-division multiplexing space-time coding wireless communication

Federated Edge Learning for the Wireless Physical Layer:Opportunities and Challenges

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China communications 2022年第8期19卷 15-30页

作者： Yiming Cui Jiajia Guo Xiangyi Li Le Liang Shi Jin national mobile communications research laboratory and frontiers science center for mobile information communication and security Southeast UniversityNanjing 210096China Purple Mountain Laboratories Nanjing 211111China

Deep learning(DL)has been applied to the physical layer of wireless communication systems,which directly extracts environment knowledge from data and outperforms conventional methods either in accuracy or computation complexity.However,most related research works employ centralized training that inevitably involves collecting training data from edge devices.The data uploading process usually results in excessive communication overhead and privacy disclosure.Alternatively,a distributed learning approach named federated edge learning(FEEL)is introduced to physical layer designs.In FEEL,all devices collaborate to train a global model only by exchanging parameters with a nearby access point.Because all datasets are kept local,data privacy is better protected and data transmission overhead can be reduced.This paper reviews the studies on applying FEEL to the wireless physical layer including channel state information acquisition,transmitter,and receiver design,which represent a paradigm shift of the DL-based physical layer design.In the meantime they also reveal several limitations inherent in FEEL,particularly when applied to the wireless physical layer,thus motivating further research efforts in the field.

关键词： deep learning federated edge learning wireless communication physical layer

Robust Fingerprint Localization Based on Massive MIMO Systems

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China communications 2022年第11期19卷 148-159页

作者： Xiaojun Wang Yijie Ren Weiguang Sun Xiaoshu Chen national mobile communications research laboratory Southeast UniversityNanjing 210000China Purple Mountain Laboratories Nanjing 210000China frontiers science center for mobile information communication and security Southeast UniversityNanjing 210000China

Location-based services have become an important part of the daily life.Fingerprint localization has been put forward to overcome the shortcomings of the traditional positioning algorithms in indoor scenario and rich scattering environment.In this paper,a single-site multiple-input multiple-output(MIMO)orthogonal frequency division multiplexing(OFDM)system is modeled,from which an angle delay channel power matrix(ADCPM)is extracted.Considering the changing environment,auto encoders are used to generate new fingerprints based on ADCPM fingerprints to improve the robustness of the fingerprints.When the scattering environment has changed beyond a certain extent,the robustness will not be able to make up for the positioning error.Under this circumstance,an updating of the fingerprint database is imperative.A new fingerprint database updating algorithm which combines a new clustering method and an updating rule based on probability is proposed.Simulation results show the desirable performance of the proposed methods.

关键词： massive multiple-input multiple-output fingerprint extraction robustness database updating

Light-controllable time-domain digital coding metasurfaces

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Advanced Photonics 2022年第2期4卷 52-58页

作者： Xin Ge Zhang Ya Lun Sun Bingcheng Zhu Wei Xiang Jiang Zaichen Zhang Tie Jun Cui Southeast University School of Information Science and EngineeringState Key Laboratory of Millimeter WavesNanjingChina Southeast University School of Information Science and EngineeringNational Mobile Communications Research LaboratoryNanjingChina Purple Mountain Laboratories NanjingChina Southeast University Frontiers Science Center for Mobile Information Communication and SecurityNanjingChina

Programmable metasurfaces enable real-time control of electromagnetic waves in a digital coding manner,which are suitable for implementing time-domain metasurfaces with strong harmonic manipulation capabilities.However,the time-domain metasurfaces are usually realized by adopting the wired electrical control method,which is effective and robust,but there are still some limitations.Here,we propose a light-controllable time-domain digital coding metasurface consisting of a full-polarization dynamic metasurface and a high-speed photoelectric detection circuit,from which the microwave reflection spectra are manipulated by time-varying light signals with periodic phase modulations.As demonstrated,the light-controllable timedomain digital coding metasurface is illuminated by the light signals with two designed time-coding sequences.The measured results show that the metasurface can well generate symmetrical harmonics and white-noise-like spectra,respectively,under such cases in the reflected wave.The proposed lightcontrollable time-varying metasurface offers a planar interface to tailor and link microwaves with lights in the time domain,which could promote the development of photoelectric hybrid metasurfaces and related multiphysics applications.

关键词： metasurface light-control time-domain metamaterial

A metasurface-based light-to-microwave transmitter for hybrid wireless communications

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Light(science & Applications) 2022年第6期11卷 1139-1148页

作者： Xin Ge Zhang Ya Lun Sun Bingcheng Zhu Wei Xiang Jiang Qian Yu Han Wei Tian Cheng-Wei Qiu Zaichen Zhang Tie Jun Cui State Key laboratory of Millimeter Waves School of Information Science and EngineeringSoutheast University210096 NanjingChina national mobile communications research laboratory School of Information Science and EngineeringSoutheast University210096 NanjingChina frontiers science center for mobile information communication and security Southeast University210096 NanjingChina Purple Mountain Laboratories 211111 NanjingChina Department of Electrical and Computer Engineering National University of SingaporeSingapore 117583Singapore

Signal conversion plays an important role in many applications such as communication,sensing,and imaging.Realizing signal conversion between optical and microwave frequencies is a crucial step to construct hybrid communication systems that combine both optical and microwave wireless technologies to achieve better features,which are highly desirable in the future wireless communications.However,such a signal conversion process typically requires a complicated relay to perform multiple operations,which will consume additional hardware/time/energy resources.Here,we report a light-to-microwave transmitter based on the time-varying and programmable metasurface integrated with a high-speed photoelectric detection circuit into a hybrid.Such a transmitter can convert a light intensity signal to two microwave binary frequency shift keying signals by using the dispersion characteristics of the metasurface to implement the frequency division multiplexing.To illustrate the metasurface-based transmitter,a hybrid wireless communication system that allows dual-channel data transmissions in a light-to-microwave link is demonstrated,and the experimental results show that two different videos can be transmitted and received simultaneously and independently.Our metasurface-enabled signal conversion solution may enrich the functionalities of metasurfaces,and could also stimulate new information-oriented applications.

关键词： microwave surface light

Channel Knowledge Map(CKM)-Assisted Multi-UAV Wireless Network:CKM Construction and UAV Placement

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Journal of communications and information Networks 2023年第3期8卷 256-270页

作者： Haoyun Li Peiming Li Gaoyuan Cheng Jie Xu Junting Chen Yong Zeng School of science and Engineering and the Future Network of Intelligence Institute(FNii)the Chinese University of Hong KongShenzhenShenzhen 518172China national mobile communications research laboratory and frontiers science center for mobile information communication and security the Southeast UniversityNanjing 210096the Purple Mountain LaboratoriesNanjing 211111China

Channel knowledge map(CKM)has recently emerged as a viable new solution to facilitate the placement and trajectory optimization for unmanned aerial vehicle(UAV)communications,by exploiting the siteand location-specific radio propagation information.This paper investigates a CKM-assisted multi-UAV wireless network,by focusing on the construction and utilization of CKMs for multi-UAV placement optimization.First,we consider the CKM construction problem when data measurements for only a limited number of points are available.Towards this end,we exploit a data-driven interpolation technique,namely the Kriging method,to construct CKMs to characterize the signal propagation environments.Next,we study the multi-UAV placement optimization problem by utilizing the constructed CKMs,in which the multiple UAVs aim to optimize their placement locations to maximize the weighted sum rate with their respectively associated ground base stations(GBSs).However,the weighted sum rate function based on the CKMs is generally non-differentiable,which renders the conventional optimization techniques relying on function derivatives inapplicable.To tackle this issue,we propose a novel iterative algorithm based on derivative-free optimization,in which a series of quadratic functions are iteratively constructed to approximate the objective function under a set of interpolation conditions,and accordingly,the UAVs’placement locations are updated by maximizing the approximate function subject to a trust region constraint.Finally,numerical results are presented to validate the performance of the proposed designs.It is shown that the Kriging method can construct accurate CKMs for UAVs.Furthermore,the proposed derivative-free placement optimization design based on the Kriging-constructed CKMs achieves a weighted sum rate that is close to the optimal exhaustive search design based on ground-truth CKMs,but with much lower implementation complexity.In addition,the proposed design is shown to significantly outperform other benchmark schemes.

关键词： UAV communications CKM CKM construction UAV placement derivative-free optimization

Metamaterials:From fundamental physics to intelligent design

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Interdisciplinary Materials 2023年第1期2卷 5-29页

作者： Ji Chen Shanshan Hu Shining Zhu Tao Li national laboratory of Solid State Microstructures Key Laboratory of Intelligent Optical Sensing and ManipulationsJiangsu Key Laboratory of Artificial Functional MaterialsCollege of Engineering and Applied SciencesSchool of PhysicsNanjing UniversityNanjingChina national mobile communications research laboratory School of Information Science and EngineeringFrontiers Science Center for Mobile Information Communication and SecuritySoutheast UniversityNanjingChina

Metamaterials are artificial structures with the ability to efficiently control light-field,attracting intensive attention in the past few decades.People have studied the working principles,design strategies,and fabrication methods of metamaterials,making this field cross and combine with many disciplines,including physics,material science,electronics,and chemistry.In recent years,with the rapid development of high-efficiency and multifunctional metasurfaces,which are a two-dimensional version of metamaterials,great efforts have been made to push this material to practical applications.In particular,the introduction of artificial intelligent(AI)algorithms enables metamaterials-based photonic devices that exhibit excellent performances and intelligent functionalities.In this review,we first introduce the basic concepts,working principles,design methods,and applications of metamaterials,and then focus on the rapidly developing metamaterials research combined with AI algorithms.Finally,we conclude this review with personal perspectives on the current problems and future directions of metamaterials research and developments.

关键词： artificial intelligence artificial neural network inverse design metamaterial metasurface

Vector Approximate Message Passing with Sparse Bayesian Learning for Gaussian Mixture Prior

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China communications 2023年第5期20卷 57-69页

作者： Chengyao Ruan Zaichen Zhang Hao Jiang Jian Dang Liang Wu Hongming Zhang national mobile communications research laboratory Frontiers Science Center for Mobile Information Communication and SecuritySoutheast UniversityNanjing 210096China Purple Mountain Laboratories No.9 Mozhou East RoadNanjing 211111China School of Artificial Intelligence Nanjing University of Information Science and TechnologyNanjing 210044China School of information and communication Engineering Beijing University of Posts and TelecommunicationsBeijing 100876China

Compressed sensing(CS)aims for seeking appropriate algorithms to recover a sparse vector from noisy linear observations.Currently,various Bayesian-based algorithms such as sparse Bayesian learning(SBL)and approximate message passing(AMP)based algorithms have been proposed.For SBL,it has accurate performance with robustness while its computational complexity is high due to matrix inversion.For AMP,its performance is guaranteed by the severe restriction of the measurement matrix,which limits its application in solving CS problem.To overcome the drawbacks of the above algorithms,in this paper,we present a low complexity algorithm for the single linear model that incorporates the vector AMP(VAMP)into the SBL structure with expectation maximization(EM).Specifically,we apply the variance auto-tuning into the VAMP to implement the E step in SBL,which decrease the iterations that require to converge compared with VAMP-EM algorithm when using a Gaussian mixture(GM)prior.Simulation results show that the proposed algorithm has better performance with high robustness under various cases of difficult measurement matrices.

关键词： sparse Bayesian learning approximate message passing compressed sensing expectation propagation

Modular Extremely Large-Scale Array communication:Near-Field Modelling and Performance Analysis

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China communications 2023年第4期20卷 132-152页

作者： Xinrui Li Haiquan Lu Yong Zeng Shi Jin Rui Zhang national mobile communications research laboratory Frontiers Science Center for Mobile Information Communication and SecuritySoutheast UniversityNanjing 210096China Purple Mountain Laboratories Nanjing 211111China The Chinese University of Hong Kong Shenzhen Research Institute of Big DataShenzhen 518172China Department of Electrical and Computer Engineering National University of SingaporeSingapore 117583Singapore

This paper investigates the wireless communication with a novel architecture of antenna arrays,termed modular extremely large-scale array(XLarray),where array elements of an extremely large number/size are regularly mounted on a shared platform with both horizontally and vertically interlaced modules.Each module consists of a moderate/flexible number of array elements with the inter-element distance typically in the order of the signal wavelength,while different modules are separated by the relatively large inter-module distance for convenience of practical deployment.By accurately modelling the signal amplitudes and phases,as well as projected apertures across all modular elements,we analyse the near-field signal-to-noise ratio(SNR)performance for modular XL-array communications.Based on the non-uniform spherical wave(NUSW)modelling,the closed-form SNR expression is derived in terms of key system parameters,such as the overall modular array size,distances of adjacent modules along all dimensions,and the user's three-dimensional(3D)location.In addition,with the number of modules in different dimensions increasing infinitely,the asymptotic SNR scaling laws are revealed.Furthermore,we show that our proposed near-field modelling and performance analysis include the results for existing array architectures/modelling as special cases,e.g.,the collocated XL-array architecture,the uniform plane wave(UPW)based far-field modelling,and the modular extremely large-scale uniform linear array(XL-ULA)of onedimension.Extensive simulation results are presented to validate our findings.

关键词： modular extremely large-scale array practical deployment projected apertures non-uniform spherical wave near-field modelling