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An overview of transmission theory and techniques of large-scale antenna systems for 5G wireless communications

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Science China(Information Sciences) 2016年第8期59卷 92-109页

作者： dongming wang Yu ZHANG Hao WEI Xiaohu YOU Xiqi GAO Jiangzhou wang National Mobile Communications Research Laboratory Southeast University School of Engineering and Digital Arts University of Kent

To meet the future demand for huge traffic volume of wireless data service, the research on the fifth generation(5G) mobile communication systems has been undertaken in recent years. It is expected that the spectral and energy efficiencies in 5G mobile communication systems should be ten-fold higher than the ones in the fourth generation(4G) mobile communication systems. Therefore, it is important to further exploit the potential of spatial multiplexing of multiple antennas. In the last twenty years, multiple-input multiple-output(MIMO) antenna techniques have been considered as the key techniques to increase the capacity of wireless communication systems. When a large-scale antenna array(which is also called massive MIMO) is equipped in a base-station, or a large number of distributed antennas(which is also called large-scale distributed MIMO)are deployed, the spectral and energy efficiencies can be further improved by using spatial domain multiple access. This paper provides an overview of massive MIMO and large-scale distributed MIMO systems, including spectral efficiency analysis, channel state information(CSI) acquisition, wireless transmission technology, and resource allocation.

关键词： the fifth generation mobile communication massive MIMO large-scale distributed antenna systems spectral efficiency channel state information acquisition multi-user MIMO resource allocation

SYMBOLIC COMPUTATION FOR THE QUALITATIVE THEORY OF DIFFERENTIAL EQUATIONS

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Acta Mathematica Scientia 2022年第6期42卷 2478-2504页

作者： Bo HUANG Wei NIU dongming wang LMIB-School of Mathematical Sciences Beihang UniversityBeijing 100191China Ecole Centrale de Pekin Beihang UniversityBeijing 100191China Beihang Hangzhou Innovation Institute Yuhang Hangzhou 310051China Centre National de la Recherche Scientifique 75794 Paris Cedea 16France

This paper provides a survey on symbolic computational approaches for the analysis of qualitative behaviors of systems of ordinary differential equations,focusing on symbolic and algebraic analysis for the local stability and bifurcation of limit cycles in the neighborhoods of equilibria and periodic orbits of the systems,with a highlight on applications to computational biology.

关键词： biological systems center-focus limit cycles qualitative analysis symbolic computation

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Uplink spectral efficiency analysis of multi-cell multi-user massive MIMO over correlated Ricean channel

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Science China(Information Sciences) 2018年第8期61卷 195-208页

作者： Juan CAO dongming wang Jiamin LI Qiang SUN Ying HU School of Electronics and Information Nantong University National Mobile Communications Research Laboratory Southeast University School of Electronics and Information Jiangsu University of Science and Technology

In this study, the performance of uplink spectral efficiency in massive multiple input multiple output(MIMO) over a spatially correlated Ricean fading channel is presented. The maximum ratio combining(MRC) receiver is employed at the base station(BS) for two channel estimation methods. The first method is based on pilot-assisted least minimum mean square error(LMMSE) estimation, whereas the second is based on line-of-sight(LOS). The respective analytical expressions of the uplink data rate are given for these two methods. Because of the existence of pilot contamination, the uplink data rate of the pilot-assisted LMMSE estimation method approaches a finite value(we call it the asymptotic rate in this study) when the BS antenna number is high. However, the data rate of the LOS method is linear with the number of BS antennas. The expression of the uplink rate of the LOS method also shows that for a Ricean channel, the spatial correlation between the BS antennas may either decrease the rate or increase the rate, depending on user location. This conclusion explains why the spatial correlation may increase rather than decrease the data rate of pilot-assisted LMMSE. We also discuss the power scaling law of the two methods, and show that the asymptotic expressions of the two methods are the same and both are independent of the antenna correlation.

关键词： massive MIMO pilot contamination Ricean fading spacial correlation uplink rate

Optimal remote radio head selection for cloud radio access networks

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Science China(Information Sciences) 2016年第10期59卷 210-221页

作者： Chunguo LI Kang SONG dongming wang Fu-Chun ZHENG Luxi YANG National Mobile Communications Research Laboratory Southeast University School of Electronic and Information Engineering Qingdao University

The cloud radio access network(C-RAN) promises significant gain to the data rate over the LTEadvanced by transferring the burdensome baseband signal processing from the remote radio heads(RRHs) to the baseband unit via the front-haul. However, scalable improvement of the overall throughput may not be maintained due to limited front-haul capacity. In this paper, we study the throughput maximization problem by selecting the active RRHs. In particular, we develop an optimum algorithm which selects a subset of active RRHs that maximize the system throughput under the front-haul constraint. In addition, the asymptotically optimum number of RRHs is derived in closed-form for low and high signal-to-noise ratio(SNR) regimes. It is demonstrated that the proposed RRH selection scheme outperforms any other existing schemes with substantial gain of achievable throughput for any given number of RRHs and any predetermined front-haul capacity constraints.

关键词： cloud radio access network(C-RAN) baseband unit(BBU) front-haul remote radio head(RRH)

Real-time in vivo visualization of tumor therapy by a near-infrared-II Ag2S quantum dot-based theranostic nanoplatform

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Nano Research 2015年第5期8卷 1637-1647页

作者： Feng Hu Chunyan Li Yejun Zhang Mao wang dongming Wu Qiangbin wang Key Laboratory of Nano-Bio Interface Division of Nanobiomedicine and i-Lab Suzhou Institute of Nano-Tech and Nano-Bionics Chinese Academy of Sciences Suzhou 215123 China

Real-time and objective feedback of therapeutic efficacies would be of great value for tumor treatment. Here, we report a smart Ag2S QD-based theranostic nanoplatform （DOX@PEG-Ag2S） obtained by loading the anti-cancer drug doxorubicin （DOX） into polyethylene glycol-coated silver sulfide quantum dots （PEG-Ag2S QDs） through hydrophobic-hydrophobic interactions, which exhibited high drug loading capability （93 wt.% of DOX to Ag2S QDs）, long circulation in blood （t1/2 = 10.3 h）, and high passive tumor-targeting efficiency （8.9% ID/gram） in living mice where % ID/gram reflects the probe concentration in terms of the percentage of the injected dose （ID） per gram of tissue. After targeting the tumor tissue, DOX from PEG-AgRS cargoes was selectively and rapidly released into cancer cells, giving rise to a significant tumor inhibition. Owing to the deep tissue penetration and high spatio-temporal resolution of Ag2S QDs fluorescence in the second near-infrared window （NIR-II）, the DOX@PEG-Ag2S enabled real-time in vivo reading of the drug targeting process and therapeutic efficacy. We expect that such a novel theranostic nanoplatform, DOX@PEG-Ag2S, with integrated drug delivery, therapy and assessment functionalities, will be highly useful for personalized treatments of tumors.

关键词： in vivo imaging Ag2S quantum dots second near-infraredwindow fluorescence drug delivery tumor therapy

Joint optimization of spectral efficiency for cell-free massive MIMO with network-assisted full duplexing

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Science China(Information Sciences) 2021年第8期64卷 156-171页

作者： Xinjiang XIA Pengcheng ZHU Jiamin LI Hao WU dongming wang Yuanxue XIN National Mobile Communications Research Laboratory Southeast University State Key Laboratory of Mobile Network and Mobile Multimedia Technology Zhongxing Telecommunication Equipment Corporation College of Internet of Things Engineering Hohai University

In this paper, we investigate duplex mode selection and transceiver design for cell-free massive multiple-input multiple-output(MIMO) with network-assisted full duplexing(NAFD), where the remote antenna units(RAUs) simultaneously serve both uplink and downlink users on the same time-frequency resource, and the joint transmission and reception are done at the central processing unit. We consider that each antenna can operate in three modes, i.e., uplink reception, downlink transmission and sleep. In particular, we model the problem as a mixed-integer optimization problem to maximize the aggregated spectral efficiency(SE) of downlinks and uplinks, where the quality-of-service constraints and power budget constraints are considered. Since the uplinks and downlinks are highly coupled, to address the design problem,we resolve the combinatorial problem by a series of nonconvex-convex approximate methods, such as equivalent formulations, iterative success convex approximations, and binary relaxations. In particular, a two-stage strategy is proposed to solve the optimization problem. In the first stage, we fix the mode selection vectors and then obtain the optimal transceivers with such a fairness strategy. In the second stage, with the transceiver parameters obtained from the first stage, we further optimize the duplex mode of each *** algorithms of the two stages will alternately run in several loops until convergence. Numerical results indicate that the proposed solution can obtain SE performance that is close to the optimal exhaustive search solution and yields a higher SE gain compared with the traditional fixed-mode duplex scheme.

关键词： cell-free massive MIMO network-assisted full duplexing mode selection success convex approximations spectral efficiency

Slicing capacity-centered mode selection and resource optimization for network-assisted full-duplex cell-free distributed massive MIMO systems

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Science China(Information Sciences) 2024年第1期67卷 203-220页

作者： Jie wang Jiamin LI Pengcheng ZHU dongming wang Hongbiao ZHANG Yue HAO Bin SHENG National Mobile Communications Research Laboratory Southeast University 2. Purple Mountain Laboratories China Mobile Research Institute

Network-assisted full-duplex(NAFD) cell-free distributed massive multiple-input multipleoutput(MIMO) systems enable uplink(UL) and downlink(DL) communications within the same timefrequency resources,which potentially reduce latency by avoiding the overhead of switching UL/DL ***,how to choose UL/DL modes remains an important factor affecting system *** the dramatic increase in the number of users and access points(APs),massive access brings significant overhead in the mode ***,the different quality of service(QoS) among users also makes the effective utilization of resources *** one of the most promising technologies in sixth-generation(6G),network slicing enables the adaptive configuration of limited UL/DL resources through the resource isolation assisted NAFD ***,we propose a slicing capacity-centered *** this scheme,APs are motivated by slicing requirements and associated slices to form different *** mode selection and resource allocation are performed within each subsystem to reduce overhead and improve resource *** implement this scheme efficiently,a double-layer deep reinforcement learning(DRL)mechanism is used to realize the joint optimization of mode selection and resource *** results show that the slicing capacity-centered scheme can effectively improve resource utilization and reduce overhead.

关键词： network-assisted full-duplex network slicing mode selection resource optimization deep reinforcement learning

Interference-Driven Designs of Nonlinear-Phase FIR Filter with Application in FBMC System

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China Communications 2016年第12期13卷 15-24页

作者： Jiangang Wen Jingyu Hua Sunan Li Kai Zhou dongming wang College of Information Engineering Zhejiang University of Technology Zhejiang Key Lab.Commun.Network&Appl. Zhejiang Univ.Tech. National Mobile Communication Research Laboratory Southeast University

In the forthcoming 5G systems, new technologies, such as amorphous networks and non-orthogonal filter bank multicarriers(FBMC), provide an effective way to accommodate high-rate transmissions. Meanwhile, the prototype filter affects the adjacent channel interference, and therefore is important for FBMC systems. Besides, once the amorphous network is taken into account, the requirement for interference controlmust be much stricter. Accordingly, this paper focuses on the design of prototype filter with better ability of interference controlling, where we exploit the nonlinear phase FIR filter(NLPFF) instead of traditional linear phase FIR filter(LPFF) to achieve more optimization spaces under a small sacrifice of linear phase. In ourdesigns, both the amplitude and phase responsesare handled independently to approach the stopband performance enhancements, in while the nearly perfect reconstruction(NPR) conditionsare relaxed by pre-specified thresholds. Computer simulations confirm the effectiveness of the NLPFF designs, and demonstrate the advantages of the proposed NLPFF in FBMC applications.

关键词： constrained minimax constrained least-square FBMC nonlinear-phase filter interference

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Beamforming prediction based on the multireward DQN framework for UAV-RIS-assisted THz communication systems

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Science China(Information Sciences) 2024年第12期67卷 333-334页

作者： Yuewei WU Peng XU Yi LV dongming wang Feifei GAO Jiangzhou wang School of Electronics and Information Engineering Shenyang Aerospace University National Mobile Communications Research Laboratory Southeast University Department of Automation Tsinghua University School of Engineering University of Kent

The terahertz(THz) frequency band offers abundant bandwidth resources but is highly sensitive to obstacles. Attaching a reconfigurable intelligent surface(RIS) to an unmanned aerial vehicle(UAV) to achieve 360-degree panoramic reflection can alleviate blockage [1]. Meanwhile,optimizing the beamforming strategies for the large-scale antenna arrays of the RIS allows for precise coverage of specific areas.

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