Página 1 dos resultados de 5436 itens digitais encontrados em 0.021 segundos

- Universidade Federal do Rio Grande do Sul
- Universidade de Brasília
- Frontiers Research Foundation
- Hindawi Publishing Corporation
- IEEE; USA
- Elsevier
- Universidade Cornell
- Institute of Electrical and Electronics Engineers (IEEE Inc)
- UNAM, Centro de Ciencias Aplicadas y Desarrollo Tecnológico
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## Planejamento de capacidade em redes corporativas para implementação de serviços VoIP; Corporate network capacity planning to voip services implementation

Fonte: Universidade Federal do Rio Grande do Sul
Publicador: Universidade Federal do Rio Grande do Sul

Tipo: Dissertação
Formato: application/pdf

POR

Relevância na Pesquisa

46.03%

#VoIP#Redes : Computadores#Processamento : Sinais#QoS#Tráfego : Voz : Computadores#Capacity planning

Este trabalho tem como objetivo o estudo da tecnologia VoIP (Voz sobre IP) e a sua aplicação em redes corporativas, enfocando o planejamento de capacidade da rede de dados para absorver serviços VoIP. Serão apresentados tópicos sobre a fundamentação teórica de VoIP (Voz sobre IP), os requisitos de arquitetura de rede e QoS (Qualidade de Serviço) exigidos pelo serviço. Mostra-se também como a metodologia para planejamento de capacidade usado em telefonia convencional pode ser adaptada aos serviços VoIP em uma rede corporativa. Foi aplicada a metodologia adaptada através de um estudo de caso em uma rede corporativa real.; This work has as objective the study of capacity planning in corporate networks for the implementation of VoIP (Voice over IP) services. We will presents topics about the theorical background of VoIP, the requirements of architecture of network and QoS (Quality of Service) demanded by the service. It will also reveal how the methodology used for planning capacity in conventional telephony, could be adjusted to the VoIP services in a corporate network. The adjusted methodology was applied in a real corporate network.

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## Modelo de avaliação da capacidade da rede de acesso metálica para o provimento de serviços suportados pela tecnologia ADSL; Model of evaluation of the metallic access network capacity for the provisions of services supported for ADSL technology

Fonte: Universidade de Brasília
Publicador: Universidade de Brasília

Tipo: Dissertação

PT_BR

Relevância na Pesquisa

46.07%

Dissertação (mestrado)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Elétrica, 2007.; A tecnologia das linhas digitais de assinantes – DSL (Digital Subscriber Line) tem sido uma boa solução para atender a demanda de serviços de dados, permitindo a transmissão em altas taxas sobre a mesma rede de acesso utilizada pelo sistema de telefonia convencional, que opera em freqüências abaixo de 4 kHz. Mas os sinais DSL trabalham com freqüências superiores e sua transmissão sobre os pares de cobre sofre altas perdas e provoca fortes induções nos demais pares do cabo, reduzindo a taxa de bits transmitidos e impondo limites sobre o comprimento da rede. Dessa forma, é importante que as operadoras de telecomunicações conheçam esses limites para utilizar ao máximo a rede para os serviços DSL, garantindo os níveis de qualidade do serviço. Este trabalho propõe um modelo para avaliar a capacidade da rede de pares metálicos para os serviços que utilizam o sistema ADSL (Asymmetric Digital Subscriber Line), sendo esse o tipo de DSL mais popular por oferecer acesso à internet e sinais de TV para clientes residenciais a baixo custo. A avaliação é feita em cima da taxa máxima transmitida pelo ADSL no sentido estação-cliente...

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## Virtual Network Capacity Expansion through Service Outsourcing

Fonte: IEEE
Publicador: IEEE

Tipo: Conferência ou Objeto de Conferência

ENG

Relevância na Pesquisa

46.11%

Roaming agreements in 3G and beyond 3G networks can greatly enhance the delivery of services to end users. The cost of service delivery to the user depends on the price charged on networks traversed by user traffic. In a QoS DiffServ environment, network resources may be sold in aggregate blocks at wholesale prices to competing ISPs. This can influence the cost of delivering services between two points using access networks owned by competing operators. Demand for network services by users varies over time and network capacities are finite; thus a fully loaded network would reject new service requests and an underutilized network will become less productive. In this paper we explore a service outsourcing scheme between competing operators that allows a custodian network operating at full capacity to outsource service provision to a candidate network. Outsourcing would be price-influenced enabling the home (custodian) operator to levy local predictable charges to the end users for services offered on the visited network. This will virtually expand the capacity of the custodian network and boost incomes for both operators.

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## Storage of Phase-Coded Patterns via STDP in Fully-Connected and Sparse Network: A Study of the Network Capacity

Fonte: Frontiers Research Foundation
Publicador: Frontiers Research Foundation

Tipo: Artigo de Revista Científica

Publicado em 23/08/2010
EN

Relevância na Pesquisa

46.16%

We study the storage and retrieval of phase-coded patterns as stable dynamical attractors in recurrent neural networks, for both an analog and a integrate and fire spiking model. The synaptic strength is determined by a learning rule based on spike-time-dependent plasticity, with an asymmetric time window depending on the relative timing between pre and postsynaptic activity. We store multiple patterns and study the network capacity. For the analog model, we find that the network capacity scales linearly with the network size, and that both capacity and the oscillation frequency of the retrieval state depend on the asymmetry of the learning time window. In addition to fully connected networks, we study sparse networks, where each neuron is connected only to a small number z ≪ N of other neurons. Connections can be short range, between neighboring neurons placed on a regular lattice, or long range, between randomly chosen pairs of neurons. We find that a small fraction of long range connections is able to amplify the capacity of the network. This imply that a small-world-network topology is optimal, as a compromise between the cost of long range connections and the capacity increase. Also in the spiking integrate and fire model the crucial result of storing and retrieval of multiple phase-coded patterns is observed. The capacity of the fully-connected spiking network is investigated...

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## Dynamic Cooperative Clustering Based Power Assignment: Network Capacity and Lifetime Efficient Topology Control in Cooperative Ad Hoc Networks

Fonte: Hindawi Publishing Corporation
Publicador: Hindawi Publishing Corporation

Tipo: Artigo de Revista Científica

Publicado em 16/03/2014
EN

Relevância na Pesquisa

46.12%

Cooperative communication (CC) is used in topology control as it can reduce the transmission power and expand the transmission range. However, all previous research on topology control under the CC model focused on maintaining network connectivity and minimizing the total energy consumption, which would lead to low network capacity, transmission interruption, or even network paralysis. Meanwhile, without considering the balance of energy consumption in the network, it would reduce the network lifetime and greatly affect the network performance. This paper tries to solve the above problems existing in the research on topology control under the CC model by proposing a power assignment (DCCPA) algorithm based on dynamic cooperative clustering in cooperative ad hoc networks. The new algorithm clusters the network to maximize network capacity and makes the clusters communicate with each other by CC. To reduce the number of redundant links between clusters, we design a static clustering method by using Kruskal algorithm. To maximize the network lifetime, we also propose a cluster head rotating method which can reach a good tradeoff between residual energy and distance for the cluster head reselection. Experimental results show that DCCPA can improve 80% network capacity with Cooperative Bridges algorithm; meanwhile...

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## On optimising the capacity and power efficiency of a wireless network

Fonte: IEEE; USA
Publicador: IEEE; USA

Tipo: Conference paper

Publicado em //2012
EN

Relevância na Pesquisa

56.16%

#topology control#wireless networks#MANET#optimisation#cross entropy#multi-objective optimisation#power control#network capacity#power efficiency

With wireless networking becoming more prevalent, the capacity and power efficiency of these networks is of concern to both users and network designers. Wireless network capacity is difficult to define, with current research providing upper bounds and throughput results for given traffic profiles. However, these measures are not suitable as optimisation metrics. This paper first outlines a novel method to measure the average capacity metric of a network. Then we compare the optimisation of power efficiency to that of average capacity and investigate the effect each metric has on the other. Finally, a new approach to network optimisation is presented in the form of a multi-objective cross entropy optimisation. This optimisation simultaneously improves the capacity and power efficiency of the networks indicating that superior solutions can be found when considering the power and capacity problem in unison. When conducting the aforementioned optimisations, the impact that the insertion of additional nodes has upon the metrics is also investigated. The current literature suggests that the additional nodes would reduce the network capacity. Our results, however, show that this is not the case when appropriate transmission powers are utilised in conjunction with the node addition.; Robert Hunjet...

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## Design and capacity performance analysis of wireless mesh network

Fonte: ACM
Publicador: ACM

Tipo: Conferência ou Objeto de Conferência
Formato: application/pdf

Publicado em //2008

Relevância na Pesquisa

46.13%

From the network operator’s point of view, the high CAPEX/OPEX cost resulting from fixed/wired backhaul links can be inhibitive to successful deployment of broadband wireless services. The emerging wireless mesh network (WMN) technology is seen as one of the potential solutions which may reduce wired backhaul dependency through multihop transmission. Despite the advantages, many remain sceptical on WMN’s network capacity and scalability performances particularly when the user density is high. This paper provides an insight on the best possible upper-bound capacity performance of WMN, taking into consideration three key design parameters namely 1) Percentage of wired backhaul points per network, 2) Mesh-to-Access Link-Rate Ratio (R) and 3) Number of radio interfaces per mesh node including hybrid radio options. These design options are compared and contrasted with different deployment densities. The results generally show that the higher the number of backhaul points, the higher the effective access capacity available to mesh node and hence user domain. Increasing the R and the number of radio per mesh node are two alternative means to push up the effective access capacity per mesh node without increasing the number of wired backhaul points. This is most significant in multi radio system where about 80% of the backhaul points can be eliminated with R= 3 in order to maintain effective access capacity close to full rate (Capacity...

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## On-line disjoint path routing for network capacity maximization in energy-constrained ad hoc networks

Fonte: Elsevier
Publicador: Elsevier

Tipo: Artigo de Revista Científica

Relevância na Pesquisa

66.1%

#Keywords: Algorithms#Channel capacity#Energy utilization#Online systems#Optimization#Telecommunication networks#Ad hoc networks#Disjoint path routing#Energy consumption optimization#Load-balanced routing#Network capacity

In this paper we consider on-line disjoint path routing in energy-constrained ad hoc networks. The objective is to maximize the network capacity, i.e. maximize the number of messages routed successfully by the network without any knowledge of future disjo

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## Network Capacity Region and Minimum Energy Function for a Delay-Tolerant Mobile Ad Hoc Network

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 10/01/2011

Relevância na Pesquisa

46.1%

We investigate two quantities of interest in a delay-tolerant mobile ad hoc
network: the network capacity region and the minimum energy function. The
network capacity region is defined as the set of all input rates that the
network can stably support considering all possible scheduling and routing
algorithms. Given any input rate vector in this region, the minimum energy
function establishes the minimum time average power required to support it. In
this work, we consider a cell-partitioned model of a delay-tolerant mobile ad
hoc network with general Markovian mobility. This simple model incorporates the
essential features of locality of wireless transmissions as well as node
mobility and enables us to exactly compute the corresponding network capacity
and minimum energy function. Further, we propose simple schemes that offer
performance guarantees that are arbitrarily close to these bounds at the cost
of an increased delay.; Comment: Extended version of IEEE/ACM Transactions on Networking article

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## On Network Coding Capacity - Matroidal Networks and Network Capacity Regions

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 02/03/2011

Relevância na Pesquisa

46.19%

One fundamental problem in the field of network coding is to determine the
network coding capacity of networks under various network coding schemes. In
this thesis, we address the problem with two approaches: matroidal networks and
capacity regions.
In our matroidal approach, we prove the converse of the theorem which states
that, if a network is scalar-linearly solvable then it is a matroidal network
associated with a representable matroid over a finite field. As a consequence,
we obtain a correspondence between scalar-linearly solvable networks and
representable matroids over finite fields in the framework of matroidal
networks. We prove a theorem about the scalar-linear solvability of networks
and field characteristics. We provide a method for generating scalar-linearly
solvable networks that are potentially different from the networks that we
already know are scalar-linearly solvable.
In our capacity region approach, we define a multi-dimensional object, called
the network capacity region, associated with networks that is analogous to the
rate regions in information theory. For the network routing capacity region, we
show that the region is a computable rational polytope and provide exact
algorithms and approximation heuristics for computing the region. For the
network linear coding capacity region...

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## Computing Bounds on Network Capacity Regions as a Polytope Reconstruction Problem

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Relevância na Pesquisa

46.12%

We define a notion of network capacity region of networks that generalizes
the notion of network capacity defined by Cannons et al. and prove its notable
properties such as closedness, boundedness and convexity when the finite field
is fixed. We show that the network routing capacity region is a computable
rational polytope and provide exact algorithms and approximation heuristics for
computing the region. We define the semi-network linear coding capacity region,
with respect to a fixed finite field, that inner bounds the corresponding
network linear coding capacity region, show that it is a computable rational
polytope, and provide exact algorithms and approximation heuristics. We show
connections between computing these regions and a polytope reconstruction
problem and some combinatorial optimization problems, such as the minimum cost
directed Steiner tree problem. We provide an example to illustrate our results.
The algorithms are not necessarily polynomial-time.; Comment: Appeared in the 2011 IEEE International Symposium on Information
Theory, 5 pages, 1 figure

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## Scalability and Dimensioning of Network-Capacity Measurement System using Reflecting Servers

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 23/05/2015

Relevância na Pesquisa

46.11%

In a class of methods for measurement of available path capacity and other
capacity-related metrics in a network, trains of probe packets are transmitted
from a sender to a receiver across a network path, and the sequences of time
stamps at sending and reception are analyzed. In large-scale implementations
there may potentially be interference between the probe-packet trains
corresponding to several concurrent measurement sessions, due to congestion in
the network and common measurement end points.
This paper outlines principles for large-scale deployments of network
capacity measurement methods using standardized network functionality. Further,
the paper provides an in-depth study of dimensioning and scalability challenges
related to the measurement end-points of such systems.
The main result is a framework for dimensioning of large-scale network
capacity measurement systems based on TWAMP. The framework is based on a method
for explicit calculation of queuelength and waiting-time distributions, where
results from M/G/1 queuing theory are combined with Monte Carlo integration.

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## The Case for Structured Random Codes in Network Capacity Theorems

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 04/02/2008

Relevância na Pesquisa

46.03%

Random coding arguments are the backbone of most channel capacity
achievability proofs. In this paper, we show that in their standard form, such
arguments are insufficient for proving some network capacity theorems:
structured coding arguments, such as random linear or lattice codes, attain
higher rates. Historically, structured codes have been studied as a stepping
stone to practical constructions. However, K\"{o}rner and Marton demonstrated
their usefulness for capacity theorems through the derivation of the optimal
rate region of a distributed functional source coding problem. Here, we use
multicasting over finite field and Gaussian multiple-access networks as
canonical examples to demonstrate that even if we want to send bits over a
network, structured codes succeed where simple random codes fail. Beyond
network coding, we also consider distributed computation over noisy channels
and a special relay-type problem.; Comment: 23 pages, 7 figures, To appear in European Transactions on
Telecommunication: Special Issue on New Directions in Information Theory

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## Storage of phase-coded patterns via STDP in fully-connected and sparse network: a study of the network capacity

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 07/09/2010

Relevância na Pesquisa

46.16%

We study the storage and retrieval of phase-coded patterns as stable
dynamical attractors in recurrent neural networks, for both an analog and a
integrate-and-fire spiking model. The synaptic strength is determined by a
learning rule based on spike-time-dependent plasticity, with an asymmetric time
window depending on the relative timing between pre- and post-synaptic
activity. We store multiple patterns and study the network capacity.
For the analog model, we find that the network capacity scales linearly with
the network size, and that both capacity and the oscillation frequency of the
retrieval state depend on the asymmetry of the learning time window. In
addition to fully-connected networks, we study sparse networks, where each
neuron is connected only to a small number z << N of other neurons. Connections
can be short range, between neighboring neurons placed on a regular lattice, or
long range, between randomly chosen pairs of neurons. We find that a small
fraction of long range connections is able to amplify the capacity of the
network. This imply that a small-world-network topology is optimal, as a
compromise between the cost of long range connections and the capacity
increase.
Also in the spiking integrate and fire model the crucial result of storing
and retrieval of multiple phase-coded patterns is observed. The capacity of the
fully-connected spiking network is investigated...

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## Beamsteering on Mobile Devices: Network Capacity and Client Efficiency

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 13/12/2010

Relevância na Pesquisa

46.06%

Current and emerging mobile devices are omni directional in wireless
communication. Such omni directionality not only limits device energy
efficiency but also poses a significant challenge toward the capacity of
wireless networks through inter-link interference. In this work, we seek to
make mobile clients directional with beamsteering. We first demonstrate that
beamsteering is already feasible to mobile devices such as Netbooks and eBook
readers in terms of form factor, power efficiency, and device mobility. We
further reveal that beamsteering mobile clients face a unique challenge to
balance client efficiency and network capacity. There is an optimal operating
point for a beamsteering mobile client in terms of the number of antennas and
transmit power that achieve the required capacity with lowest power. Finally,
we provide a distributed algorithm called BeamAdapt that allows each client to
closely approach its optimal point iteratively without central coordination. We
also offer a cellular system realization of BeamAdapt. Using Qualnet-based
simulation, we show that BeamAdapt with four antennas can reduce client power
consumption by 55% while maintaining a required network throughput for a
large-scale network, compared to the same network with omni directional mobile
clients.

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## Towards a System Theoretic Approach to Wireless Network Capacity in Finite Time and Space

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Relevância na Pesquisa

46%

In asymptotic regimes, both in time and space (network size), the derivation
of network capacity results is grossly simplified by brushing aside queueing
behavior in non-Jackson networks. This simplifying double-limit model, however,
lends itself to conservative numerical results in finite regimes. To properly
account for queueing behavior beyond a simple calculus based on average rates,
we advocate a system theoretic methodology for the capacity problem in finite
time and space regimes. This methodology also accounts for spatial correlations
arising in networks with CSMA/CA scheduling and it delivers rigorous
closed-form capacity results in terms of probability distributions. Unlike
numerous existing asymptotic results, subject to anecdotal practical concerns,
our transient one can be used in practical settings: for example, to compute
the time scales at which multi-hop routing is more advantageous than single-hop
routing.

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## Neural Network Capacity for Multilevel Inputs

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 30/07/2013

Relevância na Pesquisa

46.04%

This paper examines the memory capacity of generalized neural networks.
Hopfield networks trained with a variety of learning techniques are
investigated for their capacity both for binary and non-binary alphabets. It is
shown that the capacity can be much increased when multilevel inputs are used.
New learning strategies are proposed to increase Hopfield network capacity, and
the scalability of these methods is also examined in respect to size of the
network. The ability to recall entire patterns from stimulation of a single
neuron is examined for the increased capacity networks.; Comment: 24 pages,17 figures

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## Broadcasting for Network Lifetime Maximization in Wireless Sensor Networks

Fonte: Institute of Electrical and Electronics Engineers (IEEE Inc)
Publicador: Institute of Electrical and Electronics Engineers (IEEE Inc)

Tipo: Conference paper

Relevância na Pesquisa

45.97%

#Keywords: Broadcasting#Channel capacity#Costs#Microprocessor chips#Sensors#Topology#Transceivers#Limited battery energy#Timing heuristics#Wireless channel#Wireless sensor networks (WSN)

Networks that are dynamically formed by hundreds or thousands of inexpensive sensors are widely used in environmental monitoring, disaster recovery and the other domains. In this paper we present a protocol, LM-PB, for on-line broadcast routing in wireless sensor networks where the sensors are energy-constrained. Our protocol is aiming at maximizing the duration before the network becomes inoperative due to the lack of battery energy at sensors. An appropriate selection of transmitting sensors, which cover the rest in the network, is an efficient technique for broadcasting. LM-PB makes such selections by utilizing a novel timing heuristic, called FDL. It does not need any explicit control message and is free of exploring the network topology. Our experimental results demonstrate that LM-PB provides longer network lifetime compared with the existing passive protocols. Meanwhile we notice that the total number of successfully routed messages, termed as the network capacity, is also maximized by LM-PB. Particularly, the results indicate that the additional delay incurred by LM-PB is much less than the worst case analyzed value, and is acceptable.

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## On-Line Disjoint Path Routing for Network Capacity Maximization in Ad Hoc Networks

Fonte: Institute of Electrical and Electronics Engineers (IEEE Inc)
Publicador: Institute of Electrical and Electronics Engineers (IEEE Inc)

Tipo: Conference paper

Relevância na Pesquisa

66.09%

#Keywords: Ad hoc networks#Network capacity#Path routing#Algorithms#Bandwidth#Computer simulation#Problem solving#Routers#Telecommunication networks Ad hoc networks#Disjoint path routing#Energy consumption optimization

In this paper we consider on-line disjoint path routing in energy-constrained ad hoc networks. The objective is to maximize the network capacity, i.e., maximize the number of messages routed successfully by the network without any knowledge of future disjoint path connection request arrivals and generation rates. We first present two on-line algorithms for the problem. One is based on maximizing the network lifetime and another is based on an exponential function of energy utilization at nodes. We then conduct extensive experiments by simulations to analyze the performance of the proposed algorithms. The experimental results show that the proposed algorithms outperform those existing algorithms that do not take into account the power load balancing among the nodes.

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## Optimizing the Cellular Network Planning Process for In-Building Coverage using Simulation

Fonte: UNAM, Centro de Ciencias Aplicadas y Desarrollo Tecnológico
Publicador: UNAM, Centro de Ciencias Aplicadas y Desarrollo Tecnológico

Tipo: Artigo de Revista Científica
Formato: text/html

Publicado em 01/01/2013
EN

Relevância na Pesquisa

46.01%

The global scenario of mobile telecommunications networks suggests that the next years the number of mobile users will continue growing as well as the services demand. The biggest growth is expected mainly in Asiatic and developing countries. Particularly, the Mexican telecommunications market suggests that if the number of mobile users will continue growing in Mexico as in the last years, then the mobile networks operators should increment the network capacity and the in-building coverage in order to maximize the quality of service. Also, network operators should offer attractive plans to users in order to maximize their economic benefits. Therefore, this research study aims to develop a simulation model to analyze the services transmission in a Third Generation mobile network and maximize the network coverage and the theoretical economic benefit of network operators. The delivered services included are voice, data and video. Using this simulation model we obtained the optimal cost-effective network design in a scenario of a Mexican airport. This design consisted of six cells, each one configured with an Omni-directional antenna and capacity of seven traffic channels. Through the traffic channels were delivered the services: sound...

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