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arXiv 2018年

作者： Wang, Jin-Yuan Liu, Cheng Wang, Jun-Bo Wu, Yongpeng Lin, Min Cheng, Julian 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 Department of Electronic Engineering Shanghai Jiao Tong University Minhang200240 China School of Engineering University of British Columbia KelownaBCV1V 1V7 Canada

This paper investigates the physical-layer security for an indoor visible light communication (VLC) network consisting of a transmitter, a legitimate receiver and an eavesdropper. Both the main channel and the wiretapping channel have nonnegative inputs, which are corrupted by additive white Gaussian noises. Considering the illumination requirement and the physical characteristics of lighting source, the input is also constrained in both its average and peak optical intensities. Two scenarios are investigated: One is only with an average optical intensity constraint, and the other is with both average and peak optical intensity constraints. Based on information theory, closed-form expressions of the upper and lower bounds on secrecy capacity for the two scenarios are derived. Numerical results show that the upper and lower bounds on secrecy capacity are tight, which validates the derived closed-form expressions. Moreover, the asymptotic behaviors in the high signal-to-noise ratio (SNR) regime are analyzed from the theoretical aspects. At high SNR, when only considering the average optical intensity constraint, a small performance gap exists between the asymptotic upper and lower bounds on secrecy capacity. When considering both average and peak optical intensity constraints, the asymptotic upper and lower bounds on secrecy capacity coincide with each other. These conclusions are also confirmed by numerical results. Copyright © 2018, The Authors. All rights reserved.

关键词： Gaussian noise (electronic)

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Bandit inspired beam searching scheme for mmWave high-speed train communications

arXiv

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arXiv 2018年

作者： Wang, Jun-Bo Cheng, Ming Wang, Jin-Yuan Lin, Min Wu, Yongpeng Zhu, Huiling Wang, Jiangzhou National Mobile Communications Research Laboratory Southeast University Nanjing210096 China Key Lab of Broadband Wireless Communication and Sensor Network Technology Ministry of Education Nanjing University of Posts and Telecommunications Nanjing210003 China Shanghai Key Laboratory of Navigation and Location Based Services Shanghai Jiao Tong University Minhang200240 China School of Engineering and Digital Arts University of Kent Canterbury KentCT2 7NT United Kingdom

High-speed trains (HSTs) are being widely deployed around the world. To meet the high-rate data transmission requirements on HSTs, millimeter wave (mmWave) HST communications have drawn increasingly attentions. To realize sufficient link margin, mmWave HST systems employ directional beamforming with large antenna arrays, which results in that the channel estimation is rather time-consuming. In HST scenarios, channel conditions vary quickly and channel estimations should be performed frequently. Since the period of each transmission time interval (TTI) is too short to allocate enough time for accurate channel estimation, the key challenge is how to design an efficient beam searching scheme to leave more time for data transmission. Motivated by the successful applications of machine learning, this paper tries to exploit the similarities between current and historical wireless propagation environments. Using the knowledge of reinforcement learning, the beam searching problem of mmWave HST communications is formulated as a multi-armed bandit (MAB) problem and a bandit inspired beam searching scheme is proposed to reduce the number of measurements as many as possible. Unlike the popular deep learning methods, the proposed scheme does not need to collect and store a massive amount of training data in advance, which can save a huge amount of resources such as storage space, computing time, and power energy. Moreover, the performance of the proposed scheme is analyzed in terms of regret. The regret analysis indicates that the proposed schemes can approach the theoretical limit very quickly, which is further verified by simulation results. Copyright © 2018, The Authors. All rights reserved.

关键词： Millimeter waves

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Gridless two-dimensional DOA estimation with L-shaped array based on the cross-covariance matrix

arXiv

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arXiv 2017年

作者： Wu, Xiaohuan Zhu, Wei-Ping Yan, Jun Key Lab of Broadband Wireless Communication and Sensor Network Technology Nanjing University of Posts and Telecommunications Nanjing China Department of Electrical and Computer Engineering Concordia University Montreal Canada

The atomic norm minimization (ANM) has been successfully incorporated into the two-dimensional (2-D) direction-ofarrival (DOA) estimation problem for super-resolution. However, its computational workload might be unaffordable when the number of snapshots is large. In this paper, we propose two gridless methods for 2-D DOA estimation with L-shaped array based on the atomic norm to improve the computational efficiency. Firstly, by exploiting the cross-covariance matrix an ANM-based model has been proposed. We then prove that this model can be efficiently solved as a semi-definite programming (SDP). Secondly, a modified model has been presented to improve the estimation accuracy. It is shown that our proposed methods can be applied to both uniform and sparse L-shaped arrays and do not require any knowledge of the number of sources. Furthermore, since our methods greatly reduce the model size as compared to the conventional ANM method, and thus are much more efficient. Simulations results are provided to demonstrate the advantage of our methods. Copyright © 2017, The Authors. All rights reserved.

关键词： Computational efficiency

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Rapid computation of i-vector

Rapid computation of i-vector

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Speaker and Language Recognition Workshop, Odyssey 2016

作者： Xu, Longting Lee, Kong Aik Li, Haizhou Yang, Zhen Broadband Wireless Communication and Sensor Network Technology Key Lab Nanjing University of Posts and Telecommunications China Singapore

I-vector has been one of the state-of-the-art techniques in speaker recognition. The main computational load of the standard i-vector extraction is to evaluate the posterior covariance matrix, which is required in estimating the i-vector. This limits the potential use of i-vector on handheld devices and for large-scale cloud-based applications. Previous fast approaches focus on simplifying the posterior covariance computation. In this paper, we propose a method for rapid computation of i-vector which bypasses the need to evaluate a full posterior covariance thereby speeds up the extraction process with minor impact on the recognition accuracy. This is achieved by the use of subspace-orthonormalizing prior and the uniform-occupancy assumption that we introduce in this paper. From the experiments conducted on the extended core task of NIST SRE'10, we obtained significant speed-up with modest degradation in performance over the standard i-vector. © Odyssey 2016: Speaker and Language Recognition Workshop. All rights reserved.

关键词： Covariance matrix

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Obtaining better performance in the measurement-device-independent quantum key distribution with heralded single-photon sources

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Physical Review A 2017年第5期96卷 052337-052337页

作者： Xing-Yu Zhou Chun-Hui Zhang Chun-Mei Zhang Qin Wang Institute of Signal Processing and Transmission Nanjing University of Posts and Telecommunications Nanjing 210003 China Key Lab of Broadband Wireless Communication and Sensor Network Technology Nanjing University of Posts and Telecommunications Ministry of Education Nanjing 210003 China Key Laboratory of Quantum Information University of Science and Technology of China Hefei 230026 China

Measurement-device-independent quantum key distribution (MDI-QKD) has been widely investigated due to its remarkable advantages on the achievable transmission distance and practical security. However, the relative low key generation rate limits its real-life implementations. In this work, we adopt the newly proposed four-intensity decoy-state scheme [Phys. Rev. A 93, 042324 (2016)] to study the performance of MDI-QKD with heralded single-photon sources (HSPS). Corresponding simulation results demonstrate that the four-intensity decoy-state scheme combining HSPS can drastically improve both the key generation rate and transmission distance in MDI-QKD, which may be very promising in future MDI-QKD systems.

关键词： Quantum cryptography

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Hybrid entanglement concentration assisted with single coherent state

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Chinese Physics B 2016年第3期25卷 65-72页

作者：郭锐周澜顾世浦王兴福盛宇波 Key Laboratory of Broadband Wireless Communication and Sensor Network Technology (Ministry of Education) Nanjing University of Posts and Telecommunications College of Mathematics & Physics Nanjing University of Posts and Telecommunications College of Electronic Science and Engineering Nanjing University of Posts and Telecommunications

Hybrid entangled state （HES） is a new type of entanglement, which combines the advantages of an entangled po- larization state and an entangled coherent state. HES is widely discussed in the applications of quantum communication and computation. In this paper, we propose three entanglement concentration protocols （ECPs） for Bell-type HES, W-type HES, and cluster-type HES, respectively. After performing these ECPs, we can obtain the maximally entangled HES with some success probability. All the ECPs exploit the single coherent state to complete the concentration. These protocols are based on the linear optics, which are feasible in future experiments.

关键词： hybrid entangled state quantum communication and computation entanglement concentration

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Efficient entanglement concentration for arbitrary less-entangled NOON state assisted by single photons

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Chinese Physics B 2016年第2期25卷 98-105页

作者：周澜盛宇波 College of Mathematics and Physics Nanjing University of Posts and Telecommunications Key Laboratory of Broadband Wireless Communication and Sensor Network Technology Ministry of EducationNanjing University of Posts and Telecommunications Institute of Signal Processing Transmission Nanjing University of Posts and Telecommunications

We put forward two efficient entanglement concentration protocols （ECPs） for arbitrary less-entangled NOON state. Both ECPs only require one pair of less-entangled NOON state and an auxiliary photon. In the first ECR the auxiliary photon is shared by two parties, while in the second ECP, the auxiliary photon is only possessed by one party, which can increase the practical success probability by avoiding the transmission loss and simplify the operations. Moreover, both ECPs can be used repeatedly to get a high success probability. Based on the above features, our two ECPs, especially the second one, may be useful in the quantum information processing.

关键词： quantum communication NOON state entanglement concentration cross-Kerr nonlinearity

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Channel measurement and modeling for the 15-GHz radio band in an indoor corridor environment

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Journal of communications and Information networks 2017年第2期1卷 102-108页

作者： Hui Xu Wuxiong Zhang Yang Yang Key Lab of Wireless Sensor Network and Communication Chinese Academy of Sciences Shanghai China Shanghai Institute of Microsystem and Information Technology Chinese Academy of Sciences Shanghai China Shanghai Research Center for Wireless Communications Shanghai China

Traditional mobile communication systems mainly work on the licensed frequency band near or below 3 GHz; however, this band is becoming increasingly crowded. On the other hand, there are abundant unlicensed spectrum resources in higher frequency bands, e.g., 6 GHz, 15 GHz, and 28 GHz, and if those bands are applied, the current spectrum shortage problem could be effectively alleviated. However, the wireless channel characteristics and models are important but still unknown, and thus in this study, extensive measurements and modeling have been conducted to study the characteristics of the high-frequency 15-GHz band. Specifically, a PN(Pseudo Noise) sequence based time-domain measurement system was built and applied to measure the propagation characteristics of the LOS (Line-of-Sight) and NLOS (Non-Line-of-Sight) scenarios in an indoor corridor at 15 GHz. Then, in-depth analysis and modeling on the large-scale characteristics of wireless channels, the relationship between distance and path loss, the path loss exponent, and the shadow fading standard variance are provided. Moreover, the relationship between received power and different elevation angles was studied. In the measurement, two 25-dBi horn antennas with a 10 half-power beam width are used to change elevation angles in the transmitting terminal and azimuth angles in the receiving terminal for all measurement points. The findings and results in this work will serve as a reference and basis for future theoretical studies of the 15-GHz band.

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Deterministic realization of collective measurements via photonic quantum walks

Deterministic realization of collective measurements via pho...

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第十八届全国量子光学学术会议

作者：侯志博 Jun-Feng Tang Yuan Yuan Kang-Da Wu Guo-Yong Xiang Chuan-Feng Li Guang-Can Guo Jiangwei Shang Huangjun Zhu Jian Li 中科大 Key Laboratory of Quantum Information University of Science and Technology of ChinaCAS Synergetic Innovation Center of Quantum Information and Quantum Physics University of Science and Technology of China Naturwissenschaftlich-Technische Fakult?t Universit?t Siegen Beijing Key Laboratory of Nanophotonics and Ultrafine Optoelectronic Systems School of PhysicsBeijing Institute of Technology Institute for Theoretical Physics University of Cologne Department of Physics and Center for Field Theory and Particle Physics Fudan University State Key Laboratory of Surface Physics Fudan University Collaborative Innovation Center of Advanced Microstructures Institute of Signal Processing Transmission Nanjing University of Posts and Telecommunications Key Lab of Broadband Wireless Communication and Sensor Network Technology Nanjing University of Posts and TelecommunicationsMinistry of Education

Collective measurements on identically prepared quantum systems can extract more information than local measurements, thereby enhancing information-processing efficiency. Although this nonclassical phenomenon has been known for two decades, it has remained a challenging task to demonstrate the advantage of collective measurements in experiments. Here, we introduce a general recipe for performing deterministic collective measurements on two identically prepared qubits based on quantum walks. Using photonic quantum walks, we realize experimentally an optimized collective measurement with fidelity 0.9946 without post selection. As an application, we achieve the highest tomographic efficiency in qubit state tomography to date. Our work offers an effective recipe for beating the precision limit of local measurements in quantum state tomography and metrology. In addition, our study opens an avenue for harvesting the power of collective measurements in quantum information processing and for exploring the intriguing physics behind this power.

关键词： Deterministic realization of collective measurements via photonic quantum walks

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Characteristics analysis and optimization design of entities collaboration for cloud manufacturing

Characteristics analysis and optimization design of entities...

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作者： Li, Wenxiang Zhu, Chunsheng Wei, Xia Rodrigues, Joel J.P.C. Wang, Kun School of Information Science and Engineering Wuhan University of Science and Technology Wuhan China Department of Electrical and Computer Engineering The University of British Columbia VancouverBC Canada Instituto de Telecomunicações University of Beira Interior Covilhã Portugal Santa Rita do SapucaíMG Brazil University of Salamanca Salamanca Spain Key Lab of Broadband Wireless Communication and Sensor Network Technology Nanjing University of Posts and Telecommunications Nanjing China University ITMO St. Petersburg Russia

By applying the cloud manufacturing paradigm in the regional enterprise cluster, the enterprises or facilities may collaborate extensively for efficiently utilizing the manufacturing resources. It is valuable to explore and design the strategies of facilities selection for the autonomic control of the collaboration behaviors in production. In this paper, we model the collaboration relations in the regional enterprise cluster as a generalized social collaboration network and explore the dynamic growth process of the Facilities Collaboration network for different strategies of facilities selection, including the random selection with and without preference, and the balanced selection with and without preference. With performance indexes such as network size, the distribution of node degree and act degree, clustering coefficient, the average shortest distance, and the number of n-cliques, we present and analyze the characteristics of these strategies for cloud manufacturing. Next, based on these characteristics, we propose 2 mechanisms for self-optimization in facilities collaboration, including the dynamic weighing of facilities and the concentrated processing of successive subtasks in the process. We also analyze the mechanisms' effects on the characteristics of Facilities Collaboration network and the performance in manufacturing. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

关键词： Dynamics

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