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Universal multi-source domain adaptation

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arXiv 2020年

作者： Yin, Yueming Yang, Zhen Hu, Haifeng Wu, Xiaofu Nanjing University of Posts and Telecommunications Nanjing210003 China Key Lab of Broadband Wireless Communication and Sensor Network Technology Ministry of Education Nanjing University of Posts and Telecommunications Nanjing210003 China National Engineering Research Center of Communications and Networking Nanjing University of Posts and Telecommunications Nanjing210003 China

Unsupervised domain adaptation enables intelligent models to transfer knowledge from a labeled source domain to a similar but unlabeled target domain. Recent study reveals that knowledge can be transferred from one source domain to another unknown target domain, called Universal Domain Adaptation (UDA). However, in the real-world application, there are often more than one source domain to be exploited for domain adaptation. In this paper, we formally propose a more general domain adaptation setting, universal multi-source domain adaptation (UMDA), where the label sets of multiple source domains can be different and the label set of target domain is completely unknown. The main challenges in UMDA are to identify the common label set between each source domain and target domain, and to keep the model scalable as the number of source domains increases. To address these challenges, we propose a universal multi-source adaptation network (UMAN) to solve the domain adaptation problem without increasing the complexity of the model in various UMDA settings. In UMAN, we estimate the reliability of each known class in the common label set via the prediction margin, which helps adversarial training to better align the distributions of multiple source domains and target domain in the common label set. Moreover, the theoretical guarantee for UMAN is also provided. Massive experimental results show that existing UDA and multi-source DA (MDA) methods cannot be directly applied to UMDA and the proposed UMAN achieves the state-of-the-art performance in various UMDA settings. Copyright © 2020, The Authors. All rights reserved.

关键词： Machine learning

Synergizing Internal Electric Field and Ferroelectric Polarization of Bifeo3/Znin2s4 Z-Scheme Heterojunction for Photocatalytic Overall Water Splitting

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SSRN

SSRN 2022年

作者： Zhang, Jian Zhang, Ying Li, Lutao Yan, Wei Wang, Haiyun Cui, Yan Li, Yonghua Zhu, Xinbao Nanjing210023 China Jiangsu Nanjing210023 China Key Laboratory of Broadband Wireless Communication and Sensor Network Technology Ministry of Education Nanjing University of Posts and Telecommunications Nanjing210003 China College of Chemical Engineering Nanjing Forestry University Nanjing210037 China

Coupling internal electric field and ferroelectric polarization through the modulation of surface electronic structures to achieve high carrier separation and migration efficiency is attractive, but challenging in solar-to-chemical energy conversion. Herein, we report that coating the band gap well matched ZnIn2S4 nanoflakes on BiFeO3 polyhedron microparticles constructs the ferroelectric polarization and internal electric field enhanced Z-scheme heterojunction photocatalyst (BiFeO3 /ZnIn2S4). Benefit from the efficient photon-generated carrier separation and migration processes which triggered by enhanced spontaneous polarization and powerful internal electric field, respectively, the nanocomposites exhibit the firm half-reaction performance over hydrogen and oxygen evolution. More significantly, the optimal nanohybrids photocatalyst (ZB-3) delivered a superior photocatalytic overall water splitting activity (H2 : 87.3 μmol g-1 h-1, O 2 : 42.3 μmol g-1 h-1) with an apparent quantum efficiency of 1.12 % at 420 nm in pure water under visible light irradiation, the highest activity reported so far for ferroelectric-based heterojunction photocatalysts. The novel strategy of synergizing internal electric field and ferroelectric polarization by hybridization is proposed to boost separation and transfer efficiency of photogenerated charges in ferroelectric semiconductors. © 2022, The Authors. All rights reserved.

关键词： Heterojunctions

A hardware-efficient hybrid beamforming solution for mmwave MIMO systems

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arXiv 2018年

作者： Li, Ming Wang, Zihuang Li, Hongyu Liu, Qian Zhou, Liang School of Information and Communication Engineering Dalian University of Technology DalianLiaoning116024 China School of Computer Science and Technology Dalian University of Technology Dalian Liaoning116024 China Key Laboratory of Broadband Wireless Communications and Sensor Network Technology Ministry of Education Nanjing University of Posts and Telecommunications Nanjing210003 China

In millimeter wave (mmWave) communication systems, existing hybrid beamforming solutions generally require a large number of high-resolution phase shifters (PSs) to realize analog beamformers, which still suffer from high hardware complexity and power consumption. Targeting at this problem, this article introduces a novel hardware-efficient hybrid precoding/combining architecture, which only employs a limited number of simple phase over-samplers (POSs) and a switch (SW) network to achieve maximum hardware efficiency while maintaining satisfactory spectral efficiency performance. The POS can be realized by a simple circuit and simultaneously outputs several parallel signals with different phases. With the aid of a simple switch network, the analog precoder/combiner is implemented by feeding the signals with appropriate phases to antenna arrays or RF chains. We analyze the design challenges of this POS-SW-based hybrid beamforming architecture and present potential solutions to the fundamental issues, especially the precoder/combiner design and the channel estimation strategy. Simulation results demonstrate that this hardware-efficient structure can achieve comparable spectral efficiency but much higher energy efficiency than that of the traditional structures. Copyright © 2018, The Authors. All rights reserved.

关键词： Phase shifters

Temporally and Spatially Correlated Uplink Channel Estimation for Massive MIMO Systems

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Temporally and Spatially Correlated Uplink Channel Estimatio...

International Conference on wireless communications and Signal Processing

作者： Bin Lv Zhen Yang Youhong Feng Key Lab of Broadband Wireless Communications and Sensor Network Technology Ministry Education Nanjing University of Posts and Telecommunications

ISBN: (纸本)9781467376884

It is well known that most wireless channels are sparse. The channel impulse responses (CIRs) of certain size antenna array have a partially shared support due to the spatial correlation. Moreover, the CIRs during adjacent symbols have a common support due to the temporal correlation. In this paper, we propose a novel compressed channel estimation scheme for the uplink massive multi-input multi-out (MIMO) systems based on the assumption of time division duplexing (TDD) mode by exploiting the above mentioned temporal and spatial correlations. Then a joint subspace pursuit (JSP) algorithm is proposed. Simulation results demonstrate the proposed scheme using the JSP algorithm outperforms the classical channel estimation techniques.

关键词： Compressed channel estimation Massive MIMO Temporal and spatial correlations

Defense technology of Wormhole Attacks Based on Node Connectivity

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Defense Technology of Wormhole Attacks Based on Node Connect...

IEEE International Conference on Smart City/SocialCom/SustainCom (SmartCity)

作者： Jiu-hu Zheng Huan-yan Qian Lei Wang School of Information Technology Jiangsu Institute of Commerce Nanjing Jiangsu China School of Computer Science and Engineering Nanjing University of Science and Technology Nanjing Jiangsu China National Mobile Communications esearch Laboratory Southeast University Nanjing Jiangsu China Key Lab of Broadband Wireless Communication and Sensor Network Technology Ministry of Education Nanjing Jiangsu China

ISBN: (纸本)9781509018949

After wormhole attacks the routing mechanism of wireless sensor network (WSN) is damaged, then the hop count and distance between nodes cannot be well matched, so that the WSN becomes the anisotropic sensor network, resulting in security treats for WSN. Considering that wormhole attacks can cause the changing of node connectivity, through the theoretical analysis and derivation, the paper has proposed a method which detects wormhole attacks with the connected relation of high connectivity nodes, and optimizes routing with the help of the normal nodes outside the wormhole. Simulation results show that the algorithm can well detect wormhole attacks and has better localization accuracy In addition, the effect is more obvious in the case of the wormhole nodes with large communication radius and long distance.

关键词： wireless sensor networks Routing Probability Algorithm design and analysis Security Simulation Computer science

Resource Scheduling in URLLC and eMBB Coexistence Based on Dynamic Selection Numerology

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wireless communications and Mobile Computing 2024年第1期2024卷

作者： Wang, Lei Tao, Sijie Zhao, Lindong Zhou, Dengyou Liu, Zhe Sun, Yanbing School of Telecommunications and Information Engineering Nanjing University of Posts and Telecommunications Nanjing210003 China Key Lab. of Broadband Wireless Communication and Sensor Network Technology Ministry of Education Nanjing University of Posts and Telecommunications Nanjing210003 China School of Foreign Studies Jiangsu Open University Nanjing210036 China

This paper focuses on the resource allocation problem of multiplexing two different service scenarios, enhanced mobile broadband (eMBB) and ultrareliable low latency (URLLC) in 5G New Radio, based on dynamic numerology structure, mini-time slot scheduling, and puncturing to achieve optimal resource allocation. To obtain the optimal channel resource allocation under URLLC user constraints, this paper establishes a relevant channel model divided into two convex optimization problems: (a) eMBB resource allocation and (b) URLLC scheduling. We also determine the numerology values at the beginning of each time slot with the help of deep reinforcement learning to achieve flexible resource scheduling. The proposed algorithm is verified in simulation software, and the simulation results show that the dynamic selection of numerologies proposed in this paper can better improve the data transmission rate of eMBB users and reduce the latency of URLLC services compared with the fixed numerology scheme for the same URLLC packet arrival, while the reasonable resource allocation ensures the reliability of URLLC and eMBB communication. © 2024 Lei Wang et al.

关键词： Resource allocation

Analysis and prediction of 100 km-scale atmo-spheric duct interference in TD-LTE networks

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Journal of communications and Information networks 2017年第1期2卷 66-80页

作者： Ting Zhou Tianyu Sun Honglin Hu Hui Xu Yang Yang Ilkka Harjula Yevgeni Koucheryavy Key Lab of Wireless Sensor Network and Communication Shanghai Institute of Microsystem and Information TechnologyChinese Academy of SciencesShanghai 201800China School of Information Science and Technology ShanghaiTech UniversityShanghai 201204China Shanghai Research Center for Wireless Communication Shanghai 201204China VTT Technical Research Centre of Finland VTT FI-02044Finland Tampere University of Technology Korkeakoulunkatu 10Tampere FI-33720Finland

Atmospheric ducts are horizontal layers that occur under certain weather conditions in the lower *** signals guided in atmospheric ducts tend to experience less attenuation and spread much farther,i.e,hundreds of *** a large-scale deployed TD-LTE(Time Division Long Term Evolution)network,atmospheric ducts cause faraway downlink wireless signals to propagate beyond the designed protection distance and interfere with local uplink signals,thus resulting in a large outage *** this paper,we analyze the characteristics of ADI atmospheric duct interference(Atmospheric Duct Interference)by the use of real network-side big data from the current operated TD-LTE network owned by China *** analysis results yield the time varying and directional characteristics of *** addition,we proposed an SVM(Support Vector Machine)-classi er based spacial prediction method of ADI by machine learning over combination of real network-side big data and real meteorological ***,an implementation of ADMM(Alternating Direction Methods of Multipliers)framework is proposed to implement a distributed SVM prediction scheme,which reduces data exchange among di erent regions/cities,maintains similar prediction accuracy and is thus of a more practical use to operators.

关键词： TD-LTE interference map atmospheric duct machine learning wireless big data

On the secrecy performance of Random VLC networks with imperfect CSI and protected zone

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arXiv 2019年

作者： Wang, Jin-Yuan Qiu, Yu Lin, Sheng-Hong Wang, Jun-Bo Lin, Min Liu, Cheng Key Lab of Broadband Wireless Communication and Sensor Network Technology Nanjing University of Posts and Telecommunications Nanjing210003 China National Mobile Communications Research Laboratory Southeast University Nanjing210096 China Vertical Industry Development Department Baidu China Co. Ltd. Shanghai201210 China

This paper investigates the physical-layer security for a random indoor visible light communication (VLC) network with imperfect channel state information (CSI) and a protected zone. The VLC network consists of three nodes, i.e., a transmitter (Alice), a legitimate receiver (Bob), and an eavesdropper (Eve). Alice is fixed in the center of the ceiling, and the emitted signal at Alice satisfies the non-negativity and the dimmable average optical intensity constraint. Bob and Eve are randomly deployed on the receiver plane. By employing the protected zone and considering the imperfect CSI, the stochastic characteristics of the channel gains for both the main and the eavesdropping channels is first analyzed. After that, the closed-form expressions of the average secrecy capacity and the lower bound of secrecy outage probability are derived, respectively. Finally, Monte-Carlo simulations are provided to verify the accuracy of the derived theoretical expressions. Moreover, the impacts of the nominal optical intensity, the dimming target, the protected zone and the imperfect CSI on secrecy performance are discussed, respectively. Copyright © 2019, The Authors. All rights reserved.

关键词： Visible light communication

Complete hyperentangled Greenberger-Horne-Zeilinger state analysis for polarization and time-bin hyperentanglement

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arXiv 2022年

作者： Zeng, Zhi Institute of Signal Processing and Transmission Nanjing University of Posts and Telecommunications Nanjing210003 China Key Lab of Broadband Wireless Communication and Sensor Network Technology Ministry of Education Nanjing University of Posts and Telecommunications Nanjing210003 China School of Physics and Astronomy Shanghai Jiao Tong University Shanghai200240 China

We present an efficient scheme for the complete analysis of hyperentangled Greenberger-Horne-Zeilinger (GHZ) state in polarization and time-bin degrees of freedom with two steps. First, the polarization GHZ state is distinguished completely and nondestructively, resorting to the controlled phase flip (CPF) gate constructed by the cavity-assisted interaction. Subsequently, the time-bin GHZ state is analyzed by using the preserved polarization entanglement. With the help of CPF gate and self-assisted mechanism, our scheme can be directly generalized to the complete Nphoton hyperentangled GHZ state analysis, and it may have potential applications in the hyperentanglement-based quantum communication. © 2022, CC BY.

关键词： Polarization