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World Congress on Internet Security (WorldCIS)

作者： Alexander Vensmer Sebastian Kiesel University of Stuttgart Institute of Communication Networks and Computer Engineering Stuttgart University of Stuttgart Computing Center Networks & Communications Systems Dept. Stuttgart

This paper presents “DynFire,” a novel approach for the role-based, dynamic control of network firewalls. DynFire allows an individually controlled, secure access to the ITresources of a large organization, with particular focus on mobile users and users with restricted rights, such as subcontractors. The basic assumption behind DynFire is that, within a secured network domain separated from the Internet, we can establish a temporary binding between an IP address and a single user ID. Whenever a user connects to or disconnects from this secure network domain, firewalls are configured accordingly, using a centralized “Firewall Manager” and standardized signaling protocols.

关键词： Fires Security Protocols Internet IP networks Network topology Topology

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A distributed resource admission control mechanism supporting multicast and heterogeneous receivers for MANETs

A distributed resource admission control mechanism supportin...

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6th International ICST Conference on Wireless Internet, WICON 2011

作者： Wu, Wei Guo, Jianli Zhu, Xuan Peng, Huixing Luo, Lianhe Yan, Changjiang Bai, Yuebin Sci. and Technol. on Information Transmission and Dissemination in Communication Networks Laboratory Shijiazhuang Hebei 050081 China 54th Research Institute of CETC Shijiazhuang Hebei 050081 China School of Computer Science and Engineering Beihang University Beijing 100191 China

ISBN: (纸本)9783642304927

Resource admission control is widely introduced to control the network resources, schedule the resources and admit new services. Resource reservation protocol (RSVP) is a transport layer protocol designed to reserve resource across a network for an integrated services internet. RSVP makes an appointment for each flow and the information of status grows fast with the increase of flow number, it isn't suitable for Ad Hoc networks because the cost of connection maintenance is more expensive than establishment. In this paper, we introduce a distributed resource admission control mechanism for Ad Hoc networks (DRACM), which can adapt to dynamic changes in mobile Ad Hoc network by close to call or packet transmission time granularity. DRACM responses rapidly to re-routing, can re-build a resource reservation in minimal service degradation or least service interruption. Meanwhile, we adopt client-oriented control mechanism, can also support multicast and meet the heterogeneity of receivers. © 2012 ICST institute for computer Science, Social Informatics and Telecommunications engineering.

关键词： Mobile ad hoc networks

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Fine-grained metrics for quantifying admission control performance in mobile ad hoc networks

Fine-grained metrics for quantifying admission control perfo...

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6th International ICST Conference on Wireless Internet, WICON 2011

作者： Guo, Jianli Wu, Wei Liu, Xiaoxia Luo, Lianhe Yan, Changjiang Bai, Yuebin Sci. and Technol. on Information Transmission and Dissemination in Communication Networks Laboratory Shijiazhuang Hebei 050081 China 54th Research Institute of CETC Shijiazhuang Hebei 050081 China School of Computer Science and Engineering Beihang University Beijing 100191 China

ISBN: (纸本)9783642304927

The admission control (AC) is one of the crucial components of in QoS-providing mobile ad hoc networks (MANET). The responsibility of AC is to estimate the state of the network resources and decide whether application data can be admitted without promising more resources. AC should achieve a right balance between admission accuracy and network resource waste. It aims to admit as many sessions as possible, while utilizing the network's resources fully and efficiently. Conversely, any inaccuracy in the admission decisions can result in the pledging of more resources than are available, leading to false admissions. However, the existing metrics are only network resource or performance related, thus, it is preferred to have a metric that can measure the effective AC protocols as it influences in achieving QoS demands of the sessions. Therefore, in this work we present observation-based admission control performance metrics quantifying the satisfaction of both single session and the entire network. Also we predict the possibilities of false admission and successful completion of a session and give discuss about the metrics. Finally, we proposed a design of feedback-based admission control using the metrics we presented for feedback parameters, the verification and implementation of our design and the effectiveness of the metrics is mentioned in the future works. © 2012 ICST institute for computer Science, Social Informatics and Telecommunications engineering.

关键词： Mobile ad hoc networks

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Load balancing in cloud-based content delivery networks using adaptive server activation/deactivation

Load balancing in cloud-based content delivery networks usin...

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International Conference on engineering and Technology (ICET)

作者： Maggie Mashaly Paul J. Kühn Faculty of Information Engineering and Technology German University in Cairo Cairo Egypt Institute of Communication Networks and Computer Engineering University of Stuttgart Stuttgart Germany

Content delivery networks have been widely used for many years providing service for millions of users. Lately, many of these networks are migrating to the cloud for its numerous advantages such as lower costs, increased performance, availability and flexibility in installing new resources. This paper introduces a new approach towards load balancing as well as power reduction in cloud-based content delivery networks allowing for a controlled scaling of operational parameters within the tradeoff between power consumption and quality of experience (QoE). By applying a new proposed adaptive server activation/ deactivation model at each data center in the cloud, unutilized servers at the data center can be switched off to reduce the power consumption. This adaptive model also allows the data center to maintain its performance while being utilized up to 95%. Performance measures of data centers are crucial as there are certain user service level agreements (SLA) for the cloud subscribers that should not be violated; most important is the latency for users' requests. The proposed load balancing algorithm benefits from limited latency for requests by only shifting the load off a data center when it is almost fully loaded. When the load in a data center exceeds a critical level, processes are migrated to underloaded data centers within the cloud. The self-controlled adaptive resource management supports easing of the cloud management.

关键词： Servers Load modeling Delay Load management Adaptation models Hysteresis Data models

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Light-weight traffic parameter estimation for on-line bandwidth provisioning

Light-weight traffic parameter estimation for on-line bandwi...

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International Teletraffic Congress, ITC 21

作者： Wolfram Lautenschlaeger Frank Feller Alcatel-Lucent Deutschland AG Bell Laboratories Stuttgart Germany Institute of Communication Networks and Computer Engineering University of Stuttgart Germany

Future network components will power down unused resources to save energy. Thereto, they need to determine the required capacity by observing the traffic. In this paper, we propose a light-weight estimator for the relevant parameters of aggregated packet traffic. The estimator assumes an M/G/∞ traffic model on flow level, which has been proposed for aggregated Internet traffic. We find that the variation of the aggregate traffic rate is defined by the bit rate of contributing application streams, i.e. traffic bursts triggered by end-user applications. We identify the effect of these streams on the variance-time behavior of the aggregated traffic rate. From this, we derive an estimator for the application stream bit rate based on second-order statistics of the aggregate rate. Simulation results for inelastic and TCP traffic show a good stream rate estimation accuracy, provided that the measuring period is sufficient to capture the variance of the aggregate rate.

关键词： Bit rate Bandwidth Internet Aggregates Telecommunication traffic Multiplexing Market research

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Simple Channel Predictors for Lookahead Scheduling

Simple Channel Predictors for Lookahead Scheduling

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IEEE Vehicular Technology Conference

作者： Thomas Werthmann Matthias Kaschub Magnus Proebster Stefan Valentin Institute of Communication Networks and Computer Engineering Universit?t Stuttgart Stuttgart Germany Bell Labs Alcatel-Lucent Stuttgart Germany

ISBN: (纸本)9781467309899

To cope with highly loaded networks in diverse traffic situations, planning the scheduling for future time slots is an efficient approach [1]. However, such Lookahead scheduling relies on future Channel Quality Information (CQI), which has to be accurately predicted. In this paper, we introduce a generic model for channel prediction errors. With this model, we study how the performance of Lookahead scheduling depends on channel prediction;s accuracy. Finally, we propose a simple channel predictor. This predictor provides high accuracy, is easy to implement and of low complexity. Consequently, it is a large step in making Lookahead scheduling feasible.

关键词： loaded networks Lookahead scheduling making Lookahead

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High repetition rate all-normal dispersion Yb:fiber laser for minimum pulses

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Chinese Optics Letters 2012年第3期10卷 81-83页

作者：杨弘宇王爱民麻云凤樊仲维牛岗余锦刘洋张雪张志刚 Institute of Quantum Electronics State Key Laboratory of Advanced Optical Communication System and Networks School of Electronics Engineering and Computer SciencePeking University Beijing GK Laser Technology Co. Ltd Academy of Opto-electronics Chinese Academy of Sciences

Simulation and experimental results for high repetition rate all-normal dispersion Yb:fiber ring lasers are demonstrated for the cavity dispersion from 0.01 to 0.025 ps 2 .The simulation shows that the pulse spectrum has the potential to reach>30 nm for the dispersion of 0.014 ps 2 under practical pump power. This potential is proved by the *** spectral width of 30 nm is achieved at the repetition rate of 285 MHz under the 850-mW pump *** output power is 550 mW and dechirped pulse is 78 fs.

关键词： Yb rate High repetition rate all-normal dispersion Yb

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A realistic reference simulation environment for typical urban areas

A realistic reference simulation environment for typical urb...

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URSI International Symposium on Signals, Systems, and Electronics (ISSSE)

作者： Thomas Jansen Ulrich Tuerke Christian M. Mueller Thomas Werthmann Institute for Communications Technology Technische Universitäat Braunschweig Brunswick Germany Atesio GmbH Berlin Germany Institute of Communication Networks and Computer Engineering University of Stuttgart Germany

The increasing complexity in nowadays networks enforces the need for automation and a better understanding of radio network modeling. To ensure comparability of simulation results we propose a common simulation environment for the IC 1004. The aim of this paper is to actuate discussions on the desirable content of a common simulation environment.

关键词： Data models Load modeling Integrated circuit modeling Distribution functions Base stations Mobile communication Antennas

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490 MHz spaced optical frequency comb based on an Yb-fiber-ring laser

490 MHz spaced optical frequency comb based on an Yb-fiber-r...

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Conference on Lasers and Electro-Optics

作者： Peng Li Aimin Wang Zhigang Zhang Institute of Quantum Electronics State Key Laboratory of Advanced Optical Communication System and Networks School of Electronics Engineering and Computer Science Peking University

We demonstrate an optical frequency comb based on a 490 MHz femtosecond Yb:fiber laser. The broadened spectrum covers 500 - 1500 nm and the frequency off-set was found to be > 30 dB.

ISBN: (纸本)9781467318396

We demonstrate an optical frequency comb based on a 490 MHz femtosecond Yb:fiber laser. The broadened spectrum covers 500 - 1500 nm and the frequency off-set was found to be > 30 dB.

关键词： Ultrafast lasers Lasers Fiber Metrological Instrumentation

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Link Selection Schemes for Selection Relaying Systems With Transmit Beamforming: New and Efficient Proposals From a Distributed Concept

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IEEE Transactions on Vehicular Technology 2012年第2期61卷 533-552页

作者： Haiyang Ding Jianhua Ge Daniel Benevides da Costa Zhuoqin Jiang State Key Laboratory of Integrated Service Networks Xidian University Xi'an China Department of Computer Engineering Federal University of Ceará Sobral Ceara Brazil Xian Communication Institute Xi'an China

New and efficient link selection schemes for selection relaying systems with transmit beamforming are proposed. More specifically, assuming variable-gain and fixed-gain relaying, two distributed link selection schemes that invoke a distributed decision mechanism and rely on the success/fail signaling feedback between terminals are presented. Our analysis considers a multiantenna base station (BS) that transmits messages to a single-antenna mobile station (MS) with the aid of a single-antenna half-duplex relay station (RS). For this, the distributed link selection rules are established, based on which either the direct link or the dual-hop relaying link is selected for each information transmission process. For variable-gain relaying, the proposed scheme is implemented in a perfect distributed manner, whereas for fixed-gain relaying, the proposed scheme is performed in a distributed fashion with a certain probability. In particular, when compared with the optimal scenario, both schemes can substantially reduce the channel state information feedback overhead for the link selection process while achieving nearly identical outage performance, as manifested by the theoretical/numerical results. Furthermore, asymptotic analysis reveals that both of the proposed schemes achieve full diversity, being validated by comprehensive Monte Carlo simulations. The impacts of RS placement and the number of antennas at the BS on the probability of distributed implementation are investigated for the fixed-gain relaying case. In this case, both theoretical analysis and simulation results demonstrate that placing RS around MS can efficiently and concurrently guarantee the outage performance and the distributed implementation of the proposed scheme.

关键词： Signal to noise ratio Array signal processing Relays Transmitting antennas Delay Fading

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