检索结果-内蒙古大学图书馆

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

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.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Deterministic realization of collective measurements via photonic quantum walks

Deterministic realization of collective measurements via pho...

引用

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

来源：评论

学校读者我要写书评

暂无评论

Characteristics analysis and optimization design of entities collaboration for cloud manufacturing

Characteristics analysis and optimization design of entities...

引用

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

来源：评论

学校读者我要写书评

暂无评论

Beamforming Design and Power Allocation for secure transmission with NOMA

arXiv

引用

arXiv 2018年

作者： Feng, Youhong Yan, Shihao Yang, Zhen Yang, Nan Yuan, Jinhong Key Lab. of Ministry of Education in Broadband Wireless Communication and Sensor Network Technology Nanjing University of Posts and Telecommunications Nanjing210003 College of Physics and Electronic Information Engineering Anhui Normal University Wuhu241000 China Research School of Engineering Australian National University CanberraACT Australia School of Engineering Macquarie University NSW2109 Australia Research School of Engineering Australian National University CanberraACT2600 Australia School of Electrical Engineering and Telecommunications University of New South Wales SydneyNSW2052 Australia

In this work, we propose a novel beamforming design to enhance physical layer security of a non-orthogonal multiple access (NOMA) system with the aid of artificial noise (AN). The proposed design uses two scalars to balance the useful signal strength and interference at the strong and weak users, which is a generalized version of the existing beamforming designs in the context of physical layer security for NOMA. We determine the optimal power allocation among useful signals and AN together with the two optimal beamforming scalars in order to maximize the secrecy sum rate (SSR). Our asymptotic analysis in the high signal-to-noise ratio regime provides an efficient and near-optimal solution to optimizing the beamforming scalars and power allocation coefficients. Our analysis indicates that it is not optimal to form a beam towards either the strong user or the weak user in NOMA systems for security enhancement. In addition, the asymptotically optimal power allocation informs that, as the transmit power increases, more power should be allocated to the weak user or AN signals, while the power allocated to the strong user keeps constant. Our examination shows that the proposed novel beamforming design can significantly outperform two benchmark schemes. Copyright © 2018, The Authors. All rights reserved.

关键词： Beamforming

来源：评论

学校读者我要写书评

暂无评论

A high-resolution DOA estimation method with a family of nonconvex penalties

arXiv

引用

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 Nanjing210003 China Department of Electrical and Computer Engineering Concordia University Montreal Canada School of Communication and Information Engineering Nanjing University of Posts and Telecommunications Nanjing China

The low-rank matrix reconstruction (LRMR) approach is widely used in direction-of-arrival (DOA) estimation. As the rank norm penalty in an LRMR is NP-hard to compute, the nuclear norm (or the trace norm for a positive semidefinite (PSD) matrix) has been often employed as a convex relaxation of the rank norm. However, solving a nuclear norm convex problem may lead to a suboptimal solution of the original rank norm problem. In this paper, we propose to apply a family of nonconvex penalties on the singular values of the covariance matrix as the sparsity metrics to approximate the rank norm. In particular, we formulate a nonconvex minimization problem and solve it by using a locally convergent iterative reweighted strategy in order to enhance the sparsity and resolution. The problem in each iteration is convex and hence can be solved by using the optimization toolbox. Convergence analysis shows that the new method is able to obtain a suboptimal solution. The connection between the proposed method and the sparse signal reconstruction (SSR) is explored showing that our method can be regarded as a sparsity-based method with the number of sampling grids approaching infinity. Two feasible implementation algorithms that are based on solving a duality problem and deducing a closed-form solution of the simplified problem are also provided for the convex problem at each iteration to expedite the convergence. Extensive simulation studies are conducted to show the superiority of the proposed methods. Copyright © 2017, The Authors. All rights reserved.

关键词： Covariance matrix

来源：评论

学校读者我要写书评

暂无评论

TA3C: Teaching-Oriented Adaptive Wi-Fi Authorized Access Control Based on CSI 12

TA3C: Teaching-Oriented Adaptive Wi-Fi Authorized Access Con...

引用

12th International Conference on Mobile Ad-Hoc and sensor networks, MSN 2016

作者： Xiao, Fu Chen, Jing Xie, Xiaohui Sun, Lijuan Wang, Ruchuan College of Computer Nanjing University of Posts and Telecommunications Jiangsu China Jiangsu High Technology Research Key Laboratory for Wireless Sensor Networks Jiangsu China Key Lab of Broadband Wireless Communication and Sensor Network Technology of Ministry of Education Jiangsu China

ISBN: (纸本)9781509056965

Wi-Fi has been widely deployed with the rapid development of wireless communication technique. Wi-Fi hotspots are popular in campus, making convenient wireless network access possible. However, during class teaching, in order to avoid students browsing the web based on Wi-Fi hotspots and distracting, we hope Wi-Fi hotspots adaptively shield network access to students in the classroom, while grant access to users outside the classroom. In this work, we prototype TA3C system, a teaching-oriented adaptive Wi-Fi authorized access control scheme, using Channel State Information (CSI) to locate instead of coarse-grained and temporally unstable Received Signal Strength Indication (RSSI). CSI can distinguish multipath signals, stay stable in the same propagation environment, and show different characteristics in different propagation environments, based on which, we can distinguish outdoor and indoor environments, and identify user's location to decide whether to offer him wireless network access or not. Experiment results show that TA3C effectively achieve adaptive Wi-Fi authorized access control, which provides a guarantee for the quality of class teaching. Compared to traditional indoor localization techniques, TA3C does not need accurate location information but simply recognizes user's location indoors or outdoors, which means it does not need dedicated hardware, realizing the low-cost indoor localization technique. © 2016 IEEE.

关键词： Access control

来源：评论

学校读者我要写书评

暂无评论

CPC: A novel content popularity compensation algorithm for intelligent wireless router in user centric network

CPC: A novel content popularity compensation algorithm for i...

引用

International Conference on Intelligent System and Knowledge Engineering, ISKE

作者： Xiaoyong Lin Jie Ma Zeqiu Zhang Chao Chen Yun Xia Yang Yu Tingting Qiu Xiaoming Wang College of Tongda Nanjing University of Posts and Telecommunications Yangzhou China College of Communication & Information Engineering Nanjing University of Posts and Telecommunications Nanjing China Ministry of Education Key Lab of Broadband Wireless Communication and Sensor Network Technology (Nanjing University of Posts and Telecommunications) Nanjing China

User centric network (UCN) brought a new concept of all routers to be intelligent and definable, intelligent wireless terminals implement more video online service than general webpage exploring service, in the time of content is the king, how to provide a best user experience for the video content user under intelligent wireless routers(IWR) is a key focus in the current research of user centric network. This paper proposed a scheme of intelligent pipe between Policy server and IWR, and designed a novel content popularity compensation (CPC) algorithm in user centric network framework, the IWR obtained the user attributes and video content popularity, used the parameter of content popularity compensation index (CPI) to integrate the classified user weight (CUW) and content popularity level (CPL), the modified satisfaction degree (MSD) was designed to replace of the general index of user satisfaction degree, such as linear satisfaction degree (LSD) and simple logarithmic satisfaction (SLS). The scheduling rule was to get a maximized system MSD, and the measurement of user average satisfaction (UAS) was the evaluation standard of CPC. The simulations results showed that the CPC got the better performance than that of routine algorithms, such as max-min fairness (MMF) and Utility function (ULF), the CPC algorithm could push on the intelligent wireless router in smart home and bring a novel video content quality of experience (QoE) of future wireless video online users.

关键词： Bandwidth wireless communication Resource management Servers wireless sensor networks Telecommunications

来源：评论

学校读者我要写书评

暂无评论

Quantum Secure Direct communication with Quantum Memory

引用

Physical Review Letters 2017年第22期118卷 220501-220501页

作者： Wei Zhang Dong-Sheng Ding Yu-Bo Sheng Lan Zhou Bao-Sen Shi Guang-Can Guo Key Laboratory of Quantum Information Chinese Academy of Sciences University of Science and Technology of China Hefei Anhui 230026 China Synergetic Innovation Center of Quantum Information and Quantum Physics University of Science and Technology of China Hefei Anhui 230026 China Key Laboratory of Broadband Wireless Communication and Sensor Network Technology Nanjing University of Posts and Telecommunications Ministry of Education Nanjing 210003 China

Quantum communication provides an absolute security advantage, and it has been widely developed over the past 30 years. As an important branch of quantum communication, quantum secure direct communication (QSDC) promotes high security and instantaneousness in communication through directly transmitting messages over a quantum channel. The full implementation of a quantum protocol always requires the ability to control the transfer of a message effectively in the time domain; thus, it is essential to combine QSDC with quantum memory to accomplish the communication task. In this Letter, we report the experimental demonstration of QSDC with state-of-the-art atomic quantum memory for the first time in principle. We use the polarization degrees of freedom of photons as the information carrier, and the fidelity of entanglement decoding is verified as approximately 90%. Our work completes a fundamental step toward practical QSDC and demonstrates a potential application for long-distance quantum communication in a quantum network.

关键词： Quantum communication Quantum entanglement Quantum information with atoms & light Quantum memories Atomic ensemble

来源：评论

学校读者我要写书评

暂无评论

Measurement-Device-Independent Quantum Secure Direct communication

arXiv

引用

arXiv 2018年

作者： Zhou, Zeng-Rong Sheng, Yu-Bo Niu, Peng-Hao Yin, Liu-Guo Long, Gui-Lu State Key Laboratory of Low-dimensional Quantum Physics Beijing100084 China Department of Physics Tsinghua University Beijing100084 China Beijing National Research Center for Information Science and Technology Beijing100084 China School of Information and Technology Tsinghua University Beijing100084 China Collaborative Innovation Center of Quantum Matter Beijing100084 China Beijing Academy of Quantum Information Beijing100084 China Institute of Quantum Information and Technology Nanjing University of Posts and Telecommunications Nanjing210003 China College of Telecommunications & Information Engineering Nanjing University of Posts and Telecommunications Nanjing210003 China Key Lab of Broadband Wireless Communication and Sensor Network Technology Nanjing University of Posts and Telecommunications Ministry of Education Nanjing210003 China

Quantum secure direct communication (QSDC) is the technology to transmit secret information directly through a quantum channel without neither key nor ciphertext. It provides us with a secure communication structure that is fundamentally different from the one that we use today. In this Letter, we report the first measurement-device-independent(MDI) QSDC protocol with sequences of entangled photon pairs and single photons. It eliminates security loopholes associated with the measurement device. In addition, the MDI technique doubles the communication distance compared to those without using the technique. We also give a protocol with linear optical Bell-basis measurement, where only two of the four Bell-basis states could be measured. When the number of qubit in a sequence reduces to 1, the MDI-QSDC protocol reduces to a deterministic MDI quantum key distribution protocol, which is also presented in the Letter. Copyright © 2018, The Authors. All rights reserved.

关键词： Quantum communication

来源：评论

学校读者我要写书评

暂无评论

An anonymous ONS resolving model with trust mechanism

Boletin Tecnico/Technical Bulletin

引用

Boletin Tecnico/Technical Bulletin 2017年第3期55卷 111-118页

作者： Wang, Huqing Sun, Zhixin College of Computer Science and Technology Nanjing University of Aeronautics and Astronautics Nanjing210016 China College of Communication and Information Engineering Nanjing University of Posts and Telecommunications Nanjing210003 China Key Laboratory of Broadband Wireless Communication and Sensor Network Technology Ministry of Education Nanjing University of Posts and Telecommunications Nanjing Nanjing210003 China

Security of the Object Naming Service (ONS) resolving model is discussed in this paper and an anonymous ONS resolving model with trust mechanism is presented. This model has the following characteristics: firstly, the zero knowledge proof protocol based on elliptic curve is applied;secondly, only certifier and verifier are involved during certification, which can get rid of the bondage of trusted third-party platform;and thirdly, in order to improve efficiency, the concept of trust value is introduced. Once certified, many times of resolving services can be provided. The number of resolving service is determined by trust value. Through theoretical analysis and experimental simulation, the model has the advantages of creativity, anonymity, feasibility, and resistance against replay attack.

关键词： Internet of things

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：