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Scientific World Journal 2015年第1期2015卷 614737页

作者： Zhang, Xiaogang Zhang, Shengnan Pan, Duo Chen, Peipei Xue, Xiaobo Zhuang, Wei Chen, Jingbiao State Key Laboratory of Advanced Optical Communication Systems and Networks Institute of Quantum Electronics School of Electronics Engineering and Computer Science Beijing 100871 China

Considering the strong inhomogeneous spatial polarization and intensity distribution of spontaneous decay fluorescence due to the Hanle effect, we propose and demonstrate a universe Hanle detection configuration of electron-shelving method for optical clocks. Experimental results from Ca atomic beam optical frequency standard with electron-shelving method show that a designed Hanle detection geometry with optimized magnetic field direction, detection laser beam propagation and polarization direction, and detector position can improve the fluorescence collection rate by more than one order of magnitude comparing with that of inefficient geometry. With the fixed 423 nm fluorescence, the improved 657 nm optical frequency standard signal intensity is presented. The potential application of the Hanle detection geometry designed for facilitating the fluorescence collection for optical lattice clock with a limited solid angle of the fluorescence collection has been discussed. The Hanle detection geometry is also effective for ion detection in ion optical clock and quantum information experiments. Besides, a cylinder fluorescence collection structure is designed to increase the solid angle of the fluorescence collection in Ca atomic beam optical frequency standard. © 2015 Xiaogang Zhang et al.

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Joint Spectrum Access and Power Allocation in Full-Duplex Cognitive Cellular networks

Joint Spectrum Access and Power Allocation in Full-Duplex Co...

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IEEE International Conference on communications

作者： Tianyu Wang Yun Liao Baoxian Zhang Lingyang Song State Key Laboratory of Advanced Optical Communication Systems and Networks School of Electrical Engineering and Computer Science Peking University College of Engineering & Information Technology University of Chinese Academy of Sciences

ISBN: (纸本)9781467364300

Recently, the development in full-duplex communications has offered a great opportunity to perform simultaneous spectrum sensing and spectrum access in cognitive radio networks. In this paper, we consider a cognitive cellular network, in which the secondary base station (SBS) is a full-duplex device that can simultaneously sense the primary spectrum and transmit to the secondary users. We show that the power allocation of the SBS can affect both the sensing performance and the transmission capacity, and thus, we jointly consider the power allocation problem in the spectrum management process. First, we formulate the considered problem as a 3-dimensional matching problem and prove its NP-hardness. Then, we propose an approximate solution by extending a 2-dimensional matching algorithm. The simulation results show that the proposed algorithm can highly increase the secondary throughput of the SBS, compared with the greedy algorithm and the random algorithm.

关键词： Sensors Throughput Resource management Approximation algorithms Labeling Transmitting antennas Greedy algorithms

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Performance benchmarking of a software-based LTE SGW

Performance benchmarking of a software-based LTE SGW

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International Conference on Network and Service Management

作者： Stanislav Lange Anh Nguyen-Ngoc Steffen Gebert Thomas Zinner Michael Jarschel Andreas Köpsel Marc Sune Daniel Raumer Sebastian Gallenmüller Georg Carle Phuoc Tran-Gia Chair of Communication Networks Institute of Computer Science Würzburg Germany Nokia Munich Germany BISDN Berlin Germany Department of Informatics Technische Universität München Germany

ISBN: (纸本)9781467378574

Network Functions Virtualization (NFV) is a concept that aims at providing network operators with benefits in terms of cost, flexibility, and vendor independence by utilizing virtualization techniques to run network functions as software on commercial off-the-shelf (COTS) hardware. In contrast, prior solutions rely on specialized hardware for each function. Performance evaluation of such systems usually requires a dedicated testbed for each individual component. Rather than analyzing these proprietary black-box components, Virtualized Network Functions (VNFs) are pieces of software that run on COTS hardware and whose properties can be investigated in a generic testbed. However, depending on the underlying hardware, operating system, and implementation, VNFs might behave differently. Therefore, mechanisms for the performance evaluation of VNFs should be similar to benchmarking of software, where different implementations are compared by applying them to predefined test cases and scenarios. This work presents a first step towards a benchmarking framework for VNFs. Given two different implementations of a VNF that acts as LTE Serving Gateway (SGW), influence factors and key performance indicators are identified and a comparison between the two mechanisms is drawn.

关键词： Benchmark testing Hardware Performance evaluation Packet loss Software Ports (computers)

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Network Coding and Duty Cycling in IEEE 802.11 Wireless networks with Bidirectional Transmissions and Sleeping Periods

Network Coding and Duty Cycling in IEEE 802.11 Wireless Netw...

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IEEE Global communications Conference

作者： Raul Palacios-Trujillo Jesus Alonso-Zarate Fabrizio Granelli Frank H. P. Fitzek Nelson L. S. da Fonseca Institute of Computing University of Campinas Centre Tecnologic de Telecomunicacions de Catalunya (CTTC) Department of Information Engineering and Computer Science University of Trento Communication Networks Group Technical University of Dresden

ISBN: (纸本)9781479959532

In this paper, we propose an energy-efficient solution for implementing Network Coding (NC) in wireless networks based on the IEEE 802.11 Standard. The proposed mechanism, called GreenCode, allows nodes to duty cycle by switching to a low-power (sleep) state when they overhear coded packet transmissions that will not provide any new information for them. To facilitate the sleep operation, bidirectional transmissions involving both coded and non-coded packets between pairs of sender-receiver nodes are integrated into the operation of GreenCode. Both analytical and simulation results presented in this paper show the high energy efficiency of GreenCode with gains of up to 360% when compared to the existing mechanisms based on the IEEE 802.11 Standard.

关键词： Wireless networks DUTY CYCLE bidirectional transmission Energy efficiency Sleep high energy efficiency Network coding Ganglia COPPER ALLOY NO 360 Surgery Packet transmission Packet

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Simultaneous microwave frequency transfer and time synchronization based mode-locked pulse train over 120 km fiber 11

Simultaneous microwave frequency transfer and time synchroni...

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11th Conference on Lasers and Electro-Optics Pacific Rim, CLEO-PR 2015

作者： Chen, Xing Lu, Jinlong Zhang, Jian Cui, Yifan Lu, Xing Tian, Xusheng Ci, Cheng Liu, Bo Wu, Hong Tang, Tingsong Shi, Kebin Zhang, Zhigang State Key Laboratory of Advanced Optical Communication System Networks School of Electronics Engineering and Computer Science Peking University Beijing100871 China State Key Laboratory for Mesoscopic Physics School of Physics Peking University Beijing100871 China School of Electronic Information and Optical Engineering Nankai University Tianjin300071 China Beijing Satellite Navigation Center Beijing100094 China

We demonstrate feed-forward digital compensation technique applied in both precise frequency transfer and time synchronization. The fractional frequency instability was 6.18×10-20 at 2000 s and RMS variation of t... 详细信息

ISBN: (纸本)9781467371094

关键词： Synchronization

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Faraday anomalous dispersion optical filter at 133Cs weak 459 nm transition

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Photonics Research 2015年第5期3卷 275-278页

作者： Xiaobo Xue Duo Pan Xiaogang Zhang Bin Luo Jingbiao Chen Hong Guo State Key Laboratory of Advanced Optical Communication Systems and Networks School of Electronics Engineering and Computer Scienceand Center for Quantum Information TechnologyPeking UniversityBeijing 100871China State Key Laboratory of Information Photonics and Optical Communications Beijing University of Posts and TelecommunicationsBeijing 100876China

A 459 nm Faraday anomalous dispersion optical filter（FADOF） working at the side wings of the cesium6S1∕2→ 7P1∕2transition with weak oscillator strength is achieved. The transmittance of the higher side wing reaches 98% at a temperature of 179°C and magnetic field above 323 G. The experimental results coincide with the theoretical predictions in 1982 and 1995, which were not realized in experiments for over three decades. Due to its high transmittance, high accuracy, and narrow linewidth, the 459 nm FADOF can be applied in underwater optical communications, the building of active optical clocks, and laser frequency stabilization in active optical clocks.

关键词： FADOF work Faraday anomalous dispersion optical filter at Cs weak 459 nm transition

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Performance analysis of two-hop-relay cellular systems with queueing capability

Performance analysis of two-hop-relay cellular systems with ...

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2015 International Conference on Information and communications Technologies, ICT 2015

作者： Lu, Weifeng Gu, Mengmeng Yang, Luxi College of Computer Nanjing University of Posts and Telecommunications Nanjing210023 China School of Information Science and Engineering SouthEast University Nanjing210096 China Jiangsu High Technology Research Key Laboratory for Wireless Sensor Networks Nanjing Jiangsu210023 China Key Lab of Broadband Wireless Communication and Sensor Network Technology Nanjing University of Posts and Telecommunications Ministry of Education Jiangsu Province Nanjing Jiangsu210023 China

ISBN: (纸本)9781849199940

In this paper, we present a two-hop-relay WCDMA cellular system with queueing capability, where a call can wait in the incoming buffer at the congested Base Transceiver Station (BTS) if no channel is immediately available, so as to reduce the call blocking rate. We develop an analytic model based on Multidimensional Markov chains. Then based on this model, we can obtain the average transmission rate and the queuing delay performance of the system respectively. Finally, through numerical calculation, we analyze the impact of the various parameters on the performance of the two-hop-relay WCDMA cellular system with queueing capability.

关键词： Queueing theory

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An Adaptive Algorithm for Joint Data Detection and Channel Estimation for Meteor Burst communications Based on Per-Survivor Processing

An Adaptive Algorithm for Joint Data Detection and Channel E...

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IEEE Global communications Conference

作者： Zan Li Xiaojun Chen Yuquan Li Norman C. Beaulieu Mohammad S. Obaidat State Key Laboratory of Integrated Service Networks Xidian University China Electronics Systems Engineering Corporation Beijing School of Information and Communication Engineering Beijing University of Posts and Telecommunications Department of Computer and Information Science at Fordham University

ISBN: (纸本)9781479959532

For meteor burst communications (MBC), although per-survivor processing (PSP) based on joint data and channel estimation provides superior performance and robustness for meteor burst communications (MBC), great computational complexity constrains its application in practice. On this occasion, a dimension-down PSP (D-PSP) algorithm and a adaptive state reduction of PSP (ASRP) algorithm are proposed to curve this problem in this paper. On the basis of this, the adaptive state reduction using a dimension-down PSP (ADPSP) is proposed to combine the advantages of D-PSP and ASRP, which reduces the computational time and memory size for exponentially decaying meteor burst channels and makes maximum likelihood sequence detection (MLSD) possible for adaptive data transmission. Simulation results are presented to validate the theoretical analysis. It is shown that deploying the proposed ADPSP algorithm can achieve a good tradeoff between performance and computational complexity dynamically, and provide reliable data transmission for MBC systems with adaptive coding and modulation.

关键词： Adaptive modulation and coding MBC MLSD Per-survivor processing maximum likelihood sequence detection data detection channel estimation mecarzole MBC State reduction modulation coding REG1A gene Postsynaptic Potentials BPIFA2 gene RIDA gene data transmission dimensions Self tuning Adaptive algorithms

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Impact of intermediate layer on quality of experience of HTTP adaptive streaming

Impact of intermediate layer on quality of experience of HTT...

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International Conference on Network and Service Management

作者： Michael Seufert Tobias Hossfeld Christian Sieber Institute of Computer Science University of Würzburg Würzburg Germany Chair of Modeling of Adaptive Systems Universitat Duisburg-Essen Duisburg Nordrhein-Westfalen DE Institute for Communication Networks Technische Universität München Munich Germany

ISBN: (纸本)9781467378574

HTTP Adaptive Streaming (HAS) adapts the video quality to the current network condition by switching between different quality layers. As HAS was shown to perform better than classical video streaming, it is becoming increasingly popular. Recent research showed that quality switch amplitude and time on layer have an impact on the Quality of Experience (QoE) of HAS. However, those studies focused only on adaptation between two layers so far. This work extends these findings by taking adaptation between three layers into account. Thereby, especially the impact of an intermediate layer on user perceived quality is investigated. Crowdsourcing experiments were conducted in order to collect subjective ratings for adaptation between three layers. The results indicate that the quality of each layer and the time on each layer are important QoE parameters. This encourages the usage of temporal pooling approaches for QoE prediction and QoE-aware traffic management. Therefore, mean pooling of per-frame metrics will be applied and its performance will be validated with the subjective crowdsourcing results.

关键词： Crowdsourcing Switches Streaming media Adaptation models Video recording Quality assessment Measurement

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Fairness kills safety: A comparative study for intersection assistance applications 25

Fairness kills safety: A comparative study for intersection ...

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2014 25th IEEE Annual International Symposium on Personal, Indoor, and Mobile Radio communication, IEEE PIMRC 2014

作者： Joerer, Stefan Bloessl, Bastian Segata, Michele Sommer, Christoph Cigno, Renato Lo Dressler, Falko Computer and Communication Systems Institute of Computer Science University of Innsbruck Austria Systems and Networks Dept. of Information Engineering and Computer Science University of Trento Italy Distributed Embedded Systems Institute of Computer Science University of Paderborn Germany

ISBN: (纸本)9781479949120

We study the ability of Inter-Vehicle communication (IVC) solutions to handle real-time requirements in safety scenarios using beaconing as a communication primitive. One of the envisioned safety applications is intersection assistance. The objective of such applications is to either warn the driver or even to act autonomously if other approaching vehicles endanger the vehicle. Fairness, combined with aggressive channel access for low-latency safety messages, has been one of the main research line according to which state of the art congestion control mechanisms have been developed. We show that these solutions are not able to sufficiently support intersection assistance applications. Specifically, we show that current approaches fail exactly due to their fairness postulation. We propose a new situation-aware solution to this fairness dilemma by allowing temporary exceptions for vehicles in dangerous situations. We show the applicability for two state of the art congestion control mechanisms, namely ETSI Transmit Rate Control (TRC) and Dynamic Beaconing (DynB). Our investigation also reveals important research objectives for future IVC protocols, namely how much reactivity and situation-awareness is needed in the highly dynamic environment of vehicular networks. © 2014 IEEE.

关键词： Vehicles

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