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High-energetic ultrafast fiber laser sources tunable from 920 to 1030 nm based on tapered photonic crystal fibers

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High-energetic ultrafast fiber laser sources tunable from 92...

Laser Applications Conference, LAC 2017

作者： Niu, Fuzeng Wang, Aimin Li, Jiayin Yang, Wan Zhang, Zhigang Academy for Advanced Interdisciplinary Studies Peking University Beijing100871 China State Key Laboratory of Advanced Optical Communication System and Networks School of Electronics Engineering and Computer Science Peking University Beijing100871 China

By designing the taper structure, optimizing the tapered fiber dispersion, we demonstrate an Yb-fiber laser based ultrafast source emits 37 MHz, ~100 fs pulses widely tunable in 920-1030 nm with up to 10 nJ pulse ener... 详细信息

ISBN: (纸本)9780960038077

关键词： Fiber lasers

PAPR reduction using iterative clipping/filtering and ADMM approaches for OFDM-based mixed-numerology systems

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arXiv 2019年

作者： Liu, Xiaoran Zhang, Xiaoying Zhang, Lei Xiao, Pei Wei, Jibo Zhang, Haijun Leung, Victor C.M. Department of Electronic Science National University of Defense Technology Changsha410073 China School of Engineering University of Glasgow GlasgowG12 8QQ United Kingdom 5G Innovation Centre Institute for Communication Systems University of Surrey GuildfordGU2 7XH United Kingdom Beijing Advanced Innovation Center for Materials Genome Engineering Beijing Engineering and Technology Research Center for Convergence Networks and Ubiquitous Services University of Science and Technology Beijing Beijing100083 China Department of Electrical and Computer Engineering University of British Columbia VancouverBCV6T 1Z4 Canada

Mixed-numerology transmission is proposed to support a variety of communication scenarios with diverse requirements. However, as the orthogonal frequency division multiplexing (OFDM) remains as the basic waveform, the peak-to average power ratio (PAPR) problem is still cumbersome. In this paper, based on the iterative clipping and filtering (ICF) and optimization methods, we investigate the PAPR reduction in the mixed-numerology systems. We first illustrate that the direct extension of classical ICF brings about the accumulation of inter-numerology interference (INI) due to the repeated execution. By exploiting the clipping noise rather than the clipped signal, the noise-shaped ICF (NS-ICF) method is then proposed without increasing the INI. Next, we address the in-band distortion minimization problem subject to the PAPR constraint. By reformulation, the resulting model is separable in both the objective function and the constraints, and well suited for the alternating direction method of multipliers (ADMM) approach. The ADMM-based algorithms are then developed to split the original problem into several subproblems which can be easily solved with closed-form solutions. Furthermore, the applications of the proposed PAPR reduction methods combined with filtering and windowing techniques are also shown to be effective. Copyright © 2019, The Authors. All rights reserved.

关键词： Orthogonal frequency division multiplexing

On the Performance of X-Duplex Relaying

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On the Performance of X-Duplex Relaying

作者： Li, Shuai Zhou, Mingxin Wu, Jianjun Song, Lingyang Li, Yonghui Li, Hongbin State Key Laboratory of Advanced Optical Communication Systems and Networks School of Electronics Engineering and Computer Science Peking University Beijing100871 China School of Electrical and Information Engineering University of Sydney CamperdownNSW2006 Australia

In this paper, we study an X-duplex relay system with one source, one amplify-and-forward relay, and one destination, where the relay is equipped with a shared antenna and two radio frequency (RF) chains used for transmission or reception. X-duplex relay can adaptively configure the connection between its RF chains and antenna to operate in either half-duplex (HD) or full-duplex (FD) mode, according to the instantaneous channel conditions. We first derive the distribution of the signal to interference plus noise ratio, based on which we then analyze the outage probability, average symbol error rate (SER), and average sum rate. We also investigate the X-duplex relay with power allocation and derive the lower bound and upper bound of the corresponding outage probability. Both analytical and simulated results show that the X-duplex relay achieves a better performance over pure FD and HD schemes in terms of SER, outage probability and average sum rate, and the performance floor caused by the residual self interference can be eliminated using flexible RF chain configurations. © 2017 IEEE.

关键词： Antennas

6 Gbps real-time optical quantum random number generator based on vacuum fluctuation

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arXiv 2018年

作者： Zheng, Ziyong Zhang, Yichen Huang, Weinan Yu, Song Guo, Hong State Key Laboratory of Information Photonics and Optical Communications Beijing University of Posts and Telecommunications Beijing100876 China State Key Laboratory of Advanced Optical Communication Systems and Networks School of Electronics Engineering and Computer Science Center for Quantum Information Technology Peking University Beijing100871 China

We demonstrate a 6 Gbps real-time optical quantum random number generator by measuring vacuum fluctuation. To address the common problem that speed gap exists between fast randomness generation and slow randomness extraction in most high-speed real-time quantum random number generator systems, we present an optimized extraction algorithm based on parallel implementation of Toeplitz hashing to reduce the influence of classical noise due to the imperfection of devices. Notably, the real-time rate of randomness extraction we have achieved reaches the highest speed of 12 Gbps by occupying less computing resources and the algorithm has the ability to support hundreds of Gbps randomness extraction. By assuming that the eavesdropper with complete knowledge of the classical noise, our generator has a randomness generation speed of 6.83 Gbps and this supports the generation of 6 Gbps information-theoretically provable quantum random numbers, which are output in real-time through peripheral component interconnect express interface. Copyright © 2018, The Authors. All rights reserved.

关键词： Random processes

Terabit optical OFDM superchannel transmission via coherent carriers of a hybrid chip-scale soliton frequency comb

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arXiv 2018年

作者： Geng, Yong Huang, Xiatao Cui, Wenwen Ling, Yun Xu, Bo Zhang, Jin Yi, Xingwen Wu, Baojian Huang, Shu-Wei Qiu, Kun Wong, Chee Wei Zhou, Heng Key Lab of Optical Fiber Sensing and Communication Networks School of Information and Communication Engineering University of Electronic Science and Technology of China Chengdu611731 China Department of Electrical Computer and Energy Engineering University of Colorado BoulderCO80309 United States Fang Lu Mesoscopic Optics and Quantum Electronics Laboratory University of California Los AngelesCA90095 United States

We demonstrate seamless channel multiplexing and high bitrate superchannel transmission of coherent optical orthogonal-frequency-division-multiplexing (CO-OFDM) data signals utilizing a dissipative Kerr soliton (DKS) frequency comb generated in an on-chip microcavity. Aided by comb line multiplication through Nyquist pulse modulation, the high stability and mutual coherence among mode-locked Kerr comb lines are exploited for the first time to eliminate the guard intervals between communication channels and achieve full spectral density bandwidth utilization. Spectral efficiency as high as 2.625 bit/Hz/s is obtained for 180 CO-OFDM bands encoded with 12.75 Gbaud 8-QAM data, adding up to total bitrate of 6.885 Tb/s within 2.295 THz frequency comb bandwidth. Our study confirms that high coherence is the key superiority of Kerr soliton frequency combs over independent laser diodes, as a multi-spectral coherent laser source for high-bandwidth high-spectral-density transmission networks. Copyright © 2018, The Authors. All rights reserved.

关键词： Spectral density

Data based reconstruction of complex multiplex networks

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arXiv 2018年

作者： Ma, Chuang Chen, Han-Shuang Li, Xiang Lai, Ying-Cheng Zhang, Hai-Feng School of Mathematical Science Anhui University Hefei230601 China School of Physics and Material Science Anhui University Hefei230601 China Adaptive Networks and Control Laboratory Department of Electronic Engineering Center of Smart Networks and Systems School of Information Science and Engineering Fudan University Shanghai200433 China School of Electrical Computer and Energy Engineering Arizona State University TempeAZ85287 United States Department of Communication Engineering North University of China Taiyuan Shanxi030051 China

It has been recognized that many complex dynamical systems in the real world require a description in terms of multiplex networks, where a set of common, mutually connected nodes belong to distinct network layers and play a different role in each layer. In spite of recent progress towards data based inference of single-layer networks, to reconstruct complex systems with a multiplex structure remains largely open. We articulate a mean-field based maximum likelihood estimation framework to solve this outstanding and challenging problem. We demonstrate the power of the reconstruction framework and characterize its performance using binary time series from a class of prototypical duplex network systems that host two distinct types of spreading dynamics. In addition to validating the framework using synthetic and real-world multiplex networks, we carry out a detailed analysis to elucidate the impacts of structural and dynamical parameters as well as noise on the reconstruction accuracy and robustness. Copyright © 2018, The Authors. All rights reserved.

关键词： Network layers

Prediction of RoHCv1 and RoHCv2 compressor utilities for VoIP

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Prediction of RoHCv1 and RoHCv2 compressor utilities for VoI...

作者： Tömösközi, Máté Seeling, Patrick Ekler, Péter Fitzek, Frank H.P. Department of Automation and Applied Informatics Budapest University of Technology and Economics Hungary Department of Computer Science Central Michigan University Mount PleasantMI48859 United States Communication Networks Group Technische Universität Dresden Germany

Modern cellular networks utilising the long-term evolution (LTE) and the coming 5G set of standards face an ever-increasing demand for low-latency mobile data from connected devices. Header compression is employed to minimise the overhead for IP-based cellular network traffic, thereby decreasing the overall bandwidth usage and, subsequently, transmission delays. Here, we employ machine learning approaches for the prediction of Robust Header Compression version 1's and version 2's compression utility for VoIP transmissions, which allows the compression to dynamically adapt to varying channel conditions. We evaluate various regression models employing r2 and mean square error scores next to complexity (number of coefficients) based on an RTP specific training data set and separately captured live VoIP audio calls. We find that the proposed weighted Ridge regression model explains about at least 50 % of the observed results and the accuracy score may be as high as 94 % for some of the VoIP transmissions.

关键词： Mean square error

Performance Analysis of Full-Duplex Based Two-Way Relaying

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China communications 2016年第11期13卷 35-48页

作者： Xiaohui Sun Dandan Zhang Xiaoming Dai Beijing Engineering and Technology Research Center for Convergence Networks and Ubiquitous Services School of Computer and Communication EngineeringUniversity of Science and Technology

Cooperative communication is regarded as a promising technique for improving the reliability of wireless communication links and enhancing the radio coverage simultaneously. Unlike the conventional half-duplex(HD) mode relaying techniques,the full-duplex based two-way relaying(FD-TWR) enables data exchanges between two nodes to be completed within a single time-slot,thus resulting in a significant improvement in the spectrum efficiency. In this paper,the channel model of the FD-TWR is first given out,followed by deriving the critical performance metrics,including the received signal-to-interference-plus-noise ratio(SINR),the upper bound of the ergodic capacity and the closedform solution of the proposed FD-TWR under amplify-and-forward(AF) mode. Furthermore,taking the limit of sum-transmit-power into account,we formulate the objective function of the optimal power allocation of FD-TWR as an extreme-value problem by deriving the optimal transmit power for both the source nodes and the relay node. As long as the self-interference(SI) signal in the FD-TWR nodes can be sufficiently suppressed,the proposed scheme is shown to outperform the conventional HD mode in terms of both the ergodic capacity and the outage probability. In addition,regardless of the practical SI power,the proposedFD-TWR is always capable of achieving its best performance with an aid of the proposed optimal power allocation scheme.

关键词： full-duplex two-way relaying optimal power allocation ergodic capacity outage probability

Duplexer Design for Full-Duplex Based Wireless communications

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China communications 2016年第11期13卷 1-13页

作者： Hui Zhuang Jintao Li Weibiao Geng Xiaoming Dai Beijing Engineering and Technology Research Center for Convergence Networks and Ubiquitous Services School of Computer and Communication EngineeringUniversity of Science and Technology

The full-duplex(FD) based wireless communication devices,which are capable of concurrently transmitting and receiving signals with a single frequency band,suffer from a severe self-interference(SI) due to the large power difference between the devices' own transmission and the useful signal comes from the remote transmitters. To enable the practical FD devices to be implementable,the SI power must be sufficiently suppressed to the level of background noise power,making the received signal-to-interference-plus-noise ratio(SINR) satisfy the decoding requirement. In this paper,the design and implementation of the duplexer for facilitating SI cancellation in FD based wireless communications are investigated,with a new type of duplexer(i.e. an improved directional coupler) designed for improving the spatial suppression of the SI power. Furthermore,the practical circuit boards are designed and verified for the proposed prototype,showing that the spatial suppression capability may be up to 36 d B(i.e. much higher than that attainable in the commonly designed ferrite circulator) by using the proposed design.

关键词： full-duplex wireless communications Self-interference cancellation Duplexer Directional coupler