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Networking - ICN 2005

作者： De Siqueira, Marcos A. Figueiredo, Fabricio L. Rocha, Flavia M. F. Martins, Jose A. De Castro, Marcel C. CPqD Telecommunications Research and Development Center Rodovia Campinas Mogi-Mirim km 118 5 - 13086-902 Campinas - SP Brazil

Ad hoc networks are intrinsically dynamic with respect to mobility, traffic patterns, node density, number of nodes, physical topology, and others. This scenario imposes several challenges to the ad hoc routing protocols, and there is no single solution for all scenarios. This paper proposes the application of Policy-Based Network Management (PBNM) for dynamic reconfiguration of ad hoc networks. PBNM uses the concept of policies formed by events, conditions and actions. The occurrence of an event triggers conditions evaluation, and if evaluated to true, a set of actions should be performed. The paper contribution comprises the proposal of an ad hoc policy information model based on DEN-ng policy model for the implementation of a policy manager prototype to be integrated in the NS-2 simulator allowing dynamic reconfiguration of routing protocol parameters in simulation time;and the proposal of policies for dynamically adjusting the ad hoc routing protocol behavior. © Springer-Verlag Berlin Heidelberg 2005.

关键词： Computer networks

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A packet ring fairness protocol and its impact on TCP fairness

A packet ring fairness protocol and its impact on TCP fairne...

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GLOBECOM'05: IEEE Global telecommunications Conference, 2005

作者： Salvador, Marcos R. Uesono, Marcelo M. Da Fonseca, Nelson L. S. Telecommunications Research and Development Center CPqD Telecom and IT Solutions Campinas SP Brazil Institute of Computing State University of Campinas Campinas SP Brazil

ISBN: (纸本)0780394143

Packet-switched ring networks usually employ destination removal to exploit spatial reuse and, hence, to achieve high performance. By promoting spatial reuse, destination removal may lead to unfair access to the medium and, consequently, to unbalanced use of resources and even to node starvation. This paper introduces LCR-SD, a novel access fairness protocol for high-performance packet ring networks. LCR-SD promotes throughput fairness among flows, and it is simple and adaptive to dynamic changes in traffic patterns. This paper also analyzes the performance of LCR-SD and its impact on TCP fairness. © 2005 IEEE.

关键词： Packet networks

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A local fairness protocol for optical packet-switched WDM ring networks

A local fairness protocol for optical packet-switched WDM ri...

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2005 IEEE International Conference on Communications, ICC 2005

This paper proposes an access fairness protocol for optical packet-switched wavelength division multiplexing ring networks that employ destination removal for high-performance. The protocol aims at throughput fairness, and it combines cyclic reservations with transmission credit allocations to meet the demands of the nodes and adapt to changes in traffic characteristics dynamically and efficiently. © 2005 IEEE.

关键词： Network protocols

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Fault detection algorithm for telephone systems based on the danger theory

Fault detection algorithm for telephone systems based on the...

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4th International Conference on Artificial Immune Systems, ICARIS 2005

作者： Pinto, José Carlos L. Von Zuben, Fernando J. Telecommunications Research and Development Center CPqD Rod. Campinas - Mogi-Mirim Km 1185 Campinas/SP Brazil Department of Computer Engineering and Industrial Automation State University of Campinas Unicamp CP: 6101 13083-970 Campinas/SP Brazil

This work is aimed at presenting a fault detection algorithm composed of multiple interconnected modules, and operating according to the paradigm supported by the danger theory in immunology. This algorithm attempts to achieve significant features that a fault detection system is supposed to have when monitoring a telephone profile system. These features would basically be adaptability due to the strong variation that operational conditions may exhibit over time, and the decrease in the number of false positives, which can be generated when any abnormal behavior is erroneously classified as being a fault. Simulated scenarios have been conceived to validate the proposal, and the obtained results are then analyzed. © Springer-Verlag Berlin Heidelberg 2005.

关键词： Algorithms

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A packet ring fairness protocol and its impact on TCP fairness

A packet ring fairness protocol and its impact on TCP fairne...

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IEEE Conference and Exhibition on Global telecommunications (GLOBECOM)

作者： M.R. Salvador M.M. Uesono N.L.S. da Fonseca Telecommunications Research and Development Center CPqD Telecom and IT Solutions Sao Paulo Brazil Institute of Computing State University of Campinas Sao Paulo Brazil

关键词： Access protocols Communication system traffic control Throughput Peer to peer computing Media Access Protocol Bandwidth Transport protocols research and development telecommunications Computer networks

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A local fairness protocol for optical packet-switched WDM ring networks

A local fairness protocol for optical packet-switched WDM ri...

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IEEE International Conference on Communications (ICC)

作者： M.R. Salvador M.M. Uesono N.L.S. da Fonseca Telecommunications Research and Development Center CPqD Telecom & IT Solutions Campinas SP Brazil Institute of Computing State University of Campinas Campinas SP Brazil

关键词： Optical fiber networks Optical packet switching Wavelength division multiplexing WDM networks Access protocols Throughput Communication system traffic control Media Access Protocol research and development telecommunications

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Evaluation of the relationship between conductance and capacity measurements of VRLA batteries in Brazil

Evaluation of the relationship between conductance and capac...

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International Conference on telecommunications Energy (INTELEC)

作者： R.F. Beck M.F.N.C. Rosolem P.E.R. Cardoso L.A. Soares CPqD Foundation-Telecommunications Research and Development Center Sao Paulo Brazil

Since 1996 cpqd has been studying the application of conductance and impedance techniques to evaluate the degree of degradation of stationary lead acid batteries. The conductance technique has becoming a popular technique in Brazilian's telecommunications companies since 2002, and a very frequent question is: - which is the relationship among measurements of conductance and capacity? In order to clarify this question we decided to make some experiments. In these experiments the charge/discharge cycles was accelerated, each one composed by 23 hours of charge and a discharge at C/sub 1/, (until that the voltage of the last cell has reached 1,75 V). This experiment was done with three VRLA AGM (absorbed glass material) cells. In each cycle the conductance of each cell was measured before beginning the discharge, and the experiment was conducted until two cells reached a capacity below 50% of the nominal value. This paper reports the results obtained in accelerated life cycle testing, the relationship between conductance and capacity, the number of cycles supported by each cells, and a determination whether it is possible or not to estimate the capacity through conductance measurements.

关键词： Battery charge measurement Degradation Acceleration Voltage Impedance Glass Conducting materials Life estimation Containers Gravity

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Failure detection of stationary lead-acid batteries in service in various regions of Brazil

Failure detection of stationary lead-acid batteries in servi...

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International Conference on telecommunications Energy (INTELEC)

作者： M. Fatima N.C. Rosolem R.F. Beck L.A. Soares Telecommunications Research and Development Center CPqD Foundation Sao Paulo Brazil

The valve-regulated lead-acid battery (VRLA) was introduced in Brazilian telecommunications companies in 1992 and its application has been increasing since 1998 when the telecommunications Brazilian Company-Telebras-was privatized and also with the introduction of the wireless telecom in Brazil. For the TelCos the reliability of the battery is very important since it is the guarantee that the telecommunications systems still work when occurs an AC energy breakdown. Nowadays the technical operators' main concerns about batteries is how to know the real degradation of the battery in a brief time, without disconnect it from the energy system. Worldwide, one of the techniques that has been intensively studied for battery evaluation is the internal resistance measurement. Since 1996 cpqd has been working with impedance and conductance measurements techniques for battery evaluation and during this time we have been done several works with Brazilian Telcos. The purpose of this paper is to report the field work involving performance evaluation and failure detection of VRLA batteries through conductance, impedance and voltage measurements, sometimes with capacity tests too. The measurements were made at six-month intervals during one or two years periods. We are showing the comparative results of several examples of batteries installed in Central Offices, UPS, Outdoor Cabinets and Radio Base Station, in different regions of Brazil.

关键词： Impedance telecommunications Electric breakdown Degradation Electrical resistance measurement Measurement techniques Voltage measurement Testing Battery charge measurement Central office

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Robust Sequential Projection Algorithm: Teletraffic applications

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EUROPEAN TRANSACTIONS ON telecommunications 1997年第3期8卷 285-292页

作者： Ursini, EL Yacoub, MD DoAmaral, WC Girolami, A Telebrás Research and Development Center CPqD - Campinas - SP - Brazil Campinas State University UNICAMP - Campinas - SP - Brazil Telecommunications of S?o Paulo TELESP - S?o Paulo - SP - Brazil

An n-step ahead Robust Sequential Projection Algorithm - Robust SPA -, used for traffic forecast as well as for long term network planning is proposed. The algorithm uses the State Space Model with the state transition matrix being estimated by a relaxation technique. This lightly increases its complexity, as compared to a similar algorithm proposed in the literature, but renders the Robust SPA a better performance. The algorithm is also compared with the Expectation-Maximization technique and, in general, the Robust SPA yields a slightly poorer performance as far as the mean square error between projected and observed data is concerned. On the other hand, it is more robust and requires far less computational effort. Moreover, due to its simplicity, an automated version of the algorithm can be easily implemented for applications in which a great deal of data is to be forecasted.

关键词： Traffic forecasting observational data Network planning State space models Mean square error algorithms Relaxation Techniques Robustness Projection algorithms state transition matrix

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Optimized power performance of tunable fiber ring lasers

Optimized power performance of tunable fiber ring lasers

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SBMO/IEEE MTT-S International Conference on Microwave and Optoelectronics (IMOC)

作者： M.T.M.R. Giraldi S. Celaschi Parana Federal Center for Technological Education CPGEI CEFET-PR Brazil CPqD-TELEBRAS Brazilian Telecommunications Research and Development Center Sao Paulo Brazil

The optimized power performance of tunable fiber ring lasers governed by two-level rate equations is presented. A figure of merit and an optimization procedure are defined in order to obtain maximum output power for a given pump power. A tunable Er-doped fiber ring laser was assembled as an example. Experimental data and theoretical predictions are compared.

关键词： Tunable circuits and devices Fiber lasers Power lasers Ring lasers Optical fiber couplers Laser theory Pump lasers Erbium-doped fiber lasers Absorption Equations

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