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arXiv 2019年

作者： Li, Muye Zhang, Shun Zhao, Nan Zhang, Weile Wang, Xianbin State Key Laboratory of Integrated Services Networks Xidian University Xian710071 China School of Information and Communication Engineering Dalian University of Technology Dalian116024 China MOE Key Lab for Intelligent Networks and Network Security Xi'an Jiaotong University Xi'an710049 China Department of Electrical and Computer Engineering Western University LondonON Canada

On the time-varying channel estimation, the traditional downlink (DL) channel restoration schemes usually require the reconstruction for the covariance of downlink process noise vector, which is dependent on DL channel covariance matrix (CCM). However, the acquisition of the CCM leads to unacceptable overhead in massive MIMO systems. To tackle this problem, in this paper, we propose a novel scheme for the DL channel tracking. First, with the help of virtual channel representation (VCR), we build a dynamic uplink (UL) massive MIMO channel model with the consideration of off-grid refinement. Then, a coordinate-wise maximization based expectation maximization (EM) algorithm is adopted for capturing the model parameters, including the spatial signatures, the time-correlation factors, the off-grid bias, the channel power, and the noise power. Thanks to the angle reciprocity, the spatial signatures, timecorrelation factors and off-grid bias of the DL channel model can be reconstructed with the knowledge of UL ones. However, the other two kinds of model parameters are closely related with the carrier frequency, which cannot be perfectly inferred from the UL ones. Instead of relearning the DL model parameters with dedicated training, we resort to the optimal Bayesian Kalman filter (OBKF) method to accurately track the DL channel with the partially prior knowledge. At the same time, the model parameters will be gradually restored. Specially, the factor-graph and the Metropolis Hastings MCMC are utilized within the OBKF framework. Finally, numerical results are provided to demonstrate the efficiency of our proposed scheme. Copyright © 2019, The Authors. All rights reserved.

关键词： MIMO systems

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Multiple residual dense networks for reconfigurable intelligent surfaces cascaded channel estimation

arXiv

引用

arXiv 2021年

作者： Jin, Yu Zhang, Jiayi Huang, Chongwen Yang, Liang Xiao, Huahua Ai, Bo Wang, Zhiqin The School of Electronic and Information Engineering Beijing Jiaotong University Beijing100044 China The Frontiers Science Center for Smart High-speed Railway System Beijing Jiaotong University Beijing100044 China Zhejiang Provincial Key Lab of Information Processing Communication and Networking Zhejiang University Hangzhou310007 China College of Computer Science and Electronic Engineering Hunan University Changsha410082 China ZTE Corporation State Key Laboratory of Mobile Network Mobile Multimedia Technology Shenzhen518057 China State Key Laboratory of Rail Traffic Control and Safety Beijing Jiaotong University Beijing100044 China Henan Joint International Research Laboratory of Intelligent Networking and Data Analysis Zhengzhou University Zhengzhou450001 China Research Center of Networks and Communications Peng Cheng Laboratory Shenzhen518055 China China Academy of Information and Communications Technology Beijing100191 China

Reconfigurable intelligent surface (RIS) constitutes an essential and promising paradigm that relies programmable wireless environment and provides capability for space-intensive communications, due to the use of low-cost massive reflecting elements over the entire surfaces of man-made structures. However, accurate channel estimation is a fundamental technical prerequisite to achieve the huge performance gains from RIS. By leveraging the low rank structure of RIS channels, three practical residual neural networks, named convolutional blind denoising network, convolutional denoising generative adversarial networks and multiple residual dense network, are proposed to obtain accurate channel state information, which can reflect the impact of different methods on the estimation performance. Simulation results reveal the evolution direction of these three methods and reveal their superior performance compared with existing benchmark schemes. Copyright © 2021, The Authors. All rights reserved.

关键词： Channel estimation

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256 MHz, 1 W 780 nm femtosecond fiber laser for two-photon microscopy

256 MHz, 1 W 780 nm femtosecond fiber laser for two-photon m...

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Conference on Lasers and Electro-Optics/Pacific Rim, CLEOPR 2018

作者： Yang, Wan Wu, Danlei Liu, Guanyu Chen, Bingying Feng, Lishuang Zhang, Zhigang Wang, Aimin State Key Laboratory of Advanced Optical Communication System and Networks School of Electronics Engineering and Computer Science Peking University Beijing100871 China Key Lab Precision Opto-mechatronics Technology Ministry of Education School of Instrumentation Science and Optoelectronics Engineering Beihang University Beijing100191 China

A robust 780 nm femtosecond fiber laser was demonstrated with 191 fs pulse width, 256 MHz repetition rate and 1 W average power. It is ideal for two-photon microscopic imaging. © OSA 2018

ISBN: (纸本)9781943580453

A robust 780 nm femtosecond fiber laser was demonstrated with 191 fs pulse width, 256 MHz repetition rate and 1 W average power. It is ideal for two-photon microscopic imaging. © OSA 2018

关键词： Pulse repetition rate

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Privacy Evaluating Based on Trajectories Visualization & Analyzation

Privacy Evaluating Based on Trajectories Visualization & Ana...

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第九届中国卫星导航学术年会

作者： Huijun Dai Jie Dong Xiaolin Gui Min Zhu Zhaosheng Dai School of Electronics and Communication Engineering Xi'an Jiaotong University Shaanxi Key lab of Computer Networks Xi'an Jiaotong University

The trade-off among individual privacy, data utility and data feature of service has been a great concern when designing and evaluating privacy preserving schemes in trajectories publishing. The trajectories data is spatial and temporal correlated strongly. So, Privacy-preserving over them should take the human behaviors and their status into account. In this paper, we develop a novel method to investigate and analyze users' behaviors as well as the crowd density after abstracting users' ROIs. Finally, we evaluate the privacy stress via a well-designed indictor combing the trajectories visualization and analyzation. Experiments show that the method is capable of effectively finding both crowd living patterns and distribution, and the proposed indictor can quantize the mobility data utility precisely in grid.

关键词： Trajectory privacy preserving privacy evaluation ROI POI crowd density matrix heat map

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Power-Aware virtual network function placement and routing using an abstraction technique

arXiv

引用

arXiv 2018年

作者： Varasteh, Amir Andrade, Marilet De MacHuca, Carmen Mas Wosinska, Lena Kellerer, Wolfgang Department of Communication Networks Department of Electrical and Computer Engineering Technical University of Munich Germany Optical Networks Lab. KTH Royal Institute of Technology Stockholm Sweden

The Network Function Virtualization (NFV) is very promising for efficient provisioning of network services and is attracting a lot of attention. NFV can be implemented in commercial off-the-shelf servers or Physical Machines (PMs), and many network services can be offered as a sequence of Virtual Network Functions (VNFs), known as VNF chains. Furthermore, many existing network devices (e.g., switches) and collocated PMs are underutilized or over-provisioned, resulting in low powerefficiency. In order to achieve more energy efficient systems, this work aims at designing the placement of VNFs such that the total power consumption in network nodes and PMs is minimized, while meeting the delay and capacity requirements of the foreseen demands. Based on existing switch and PM power models, we propose a Integer Linear Programming (ILP) formulation to find the optimal solution. We also propose a heuristic based on the concept of Blocking Islands (BI), and a baseline heuristic based on the Betweenness Centrality (BC) property of the graph. Both heuristics and the ILP solutions have been compared in terms of total power consumption, delay, demands acceptance rate, and computation time. Our simulation results suggest that BIbased heuristic is superior compared with the BC-based heuristic, and very close to the optimal solution obtained from the ILP in terms of total power consumption and demands acceptance rate. Compared to the ILP, the proposed BI-based heuristic is significantly faster and results in 22% lower end-to-end delay, with a penalty of consuming 6% more power in average. Copyright © 2018, The Authors. All rights reserved.

关键词： Network function virtualization

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Multi-antenna covert communications with random access protocol

arXiv

引用

arXiv 2019年

作者： Zhang, Weile Zhao, Nan Zhang, Shun Richard Yu, F. School of Electronic and Information Engineering Xi'an Jiaotong University Xi'an Shaanxi710049 China School of Information and Communication Engineering Dalian University of Technology Dalian China State Key Lab of Integrated Services Networks Xidian University Xi'an Shaanxi710071 China Department of Systems and Computer Engineering Carleton University OttawaONK1S 5B6 Canada

In this paper, we consider the issue of covert communications with random access protocol. We consider that the legitimate user Bob has no priori knowledge about packet arrival time and thus employs data-aided frame detection based on reference sequence. The warden user Willie tries to detect this covert communication by using a radiometer. The detection performance analysis is provided for both Bob and Willie under Rayleigh fading channel. It is demonstrated that the covert performance can benefit from the increase of the frame length or the number of receive antennas from frame detection perspective. Numerical results are provided to verify the proposed studies. Copyright © 2019, The Authors. All rights reserved.

关键词： Receiving antennas

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Evolutionary Cryptography Theory-Based Generating Method for Secure ECs

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Tsinghua Science and Technology 2017年第5期22卷 499-510页

作者： Chao Wang Feng Hu Huanguo Zhang Jie Wu the Key Laboratory of Specialty Fiber Optics and Optical Access Networks School of Communication and Information EngineeringShanghai University the Department of Computer and Information Sciences Temple University the Key Lab of Aerospace Information Security and Trusted Computing Wuhan University

Ant Colony Optimization （AGO） has the character of positive feedback, distributed searching, and greedy searching. It is applicable to optimization grouping problems. Traditional cryptographic research is mainly based on pure mathematical methods which have complicated theories and algorithm. It seems that there is no relationship between cryptography and ACO. Actually, some problems in cryptography are due to optimization grouping problems that could be improved using an evolutionary algorithm. Therefore, this paper presents a new method of solving secure curve selection problems using ACO. We improved Complex Multiplication （CM） by combining Evolutionary Cryptography Theory with Weber polynomial solutions. We found that ACO makes full use of valid information generated from factorization and allocates computing resource reasonably. It greatly increases the performance of Weber polynomial solutions. Compared with traditional CM, which can only search one root once time, our new method searches all roots of the polynomial once, and the average time needed to search for one root reduces rapidly. The more roots are searched, the more ECs are obtained.

关键词： ECs Weber polynomial evolutionary algorithm ant algorithm complex multiplication

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Simple Method for Realizing Weil Theorem in Secure ECC Generation

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Tsinghua Science and Technology 2017年第5期22卷 511-519页

作者： Feng Hu Chao Wang Huanguo Zhang Jie Wu the Key Laboratory of Specialty Fiber Optics and Optical Access Networks School of Communication and Information EngineeringShanghai University the Department of Computer and Information Sciences Temple University the Key Lab of Aerospace Information Security and Trusted Computing Wuhan University

How to quickly compute the number of points on an Elliptic Curve （EC） has been a longstanding challenge. The computational complexity of the algorithm usually employed makes it highly inefficient. Unlike the general EC, a simple method called the Weil theorem can be used to compute the order of an EC characterized by a small prime number, such as the Kobltiz EC characterized by two. The fifteen secure ECs recommended by the National Institute of Standards and Technology （NIST） Digital Signature Standard contain five Koblitz ECs whose maximum base domain reaches 571 bits. Experimental results show that the computation speed decreases for base domains exceeding 600 bits. In this paper, we propose a simple method that combines the Weil theorem with Pascals triangle, which greatly reduces the computational complexity. We have validated the performance of this method for base fields ranging from 2l^100 to 2^1000. Furthermore, this new method can be generalized to any ECs characterized by any small prime number.

关键词： Elliptic Curves （ECs） Pascal＇s triangle Weil theorem

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Demonstration of 50Gb/s/λ symmetric PAM4 TDM-PON with 10G-class optics and DSP-free ONUs in the O-band

Demonstration of 50Gb/s/λ symmetric PAM4 TDM-PON with 10G-c...

引用

Optical Fiber communication Conference, OFC 2018

作者： Zhang, Kuo Zhuge, Qunbi Xin, Haiyun Xing, Zhenping Xiang, Meng Fan, Sujie Yi, Lilin Hu, Weisheng Plant, David V. State Key Lab of Advanced Optical Communication System and Networks Shanghai Jiao Tong University Shanghai200240 China Department of Electrical and Computer Engineering McGill University MontrealQCH3A 2A7 Canada Ciena Corporation OttawaONK2K 0L1 Canada

We demonstrate a 50Gb/s/λ PAM4 TDM-PON based on 10G-class DMLs and PDs in Oband with downlink pre-compensation and uplink post-equalization. Results show that, without any DSP in the ONU, 29dB optical power budget is... 详细信息

ISBN: (纸本)9781943580385

关键词： Budget control

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Correction to “Fulcrum: Flexible Network Coding for Heterogeneous Devices”

引用

IEEE Access 2021年 9卷 108199-108199页

作者： Daniel E. Lucani Morten V. Pedersen Diego Ruano Chres W. Sørensen Frank H. P. Fitzek Janus Heide Olav Geil Vu Nguyen Martin Reisslein Aarhus University Aarhus Denmark Steinwurf ApS Aalborg Denmark IMUVA-Mathematics Research Institute University of Valladolid Valladolid Spain Aalborg University Aalborg Denmark Danish Ministry of Defence Acquisition and Logistics Organization Copenhagen Denmark 5G Lab Germany Deutsche Telekom Chair of Communication Networks Technische Universität Dresden Dresden Germany Centre for Tactile Internet with Human-in-the-Loop (CeTI) Technische Universität Dresden Dresden Germany School of Electrical Computer and Energy Engineering Arizona State University Tempe AZ USA

In the above article [1] , in Section II-B.1)a, titled “Outer Encoding,” the first sentence of the second paragraph should be corrected to consistently use $\Omega _{j}$ to denote the coded packets, i.e., this sentence should state: “For systematic outer encoding, the outer encoding vectors for coded packets $\Omega _{j},\,\,j = 1, 2, \ldots, n$ , form an identity matrix of dimension $n \times n$ , i.e., coded packets $\Omega _{j}, j = 1, 2, \ldots, n$ , are identical to the source packets $P_{j}$ .”

关键词： Systematics Network coding Encoding

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