• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 41
  • 19
  • 6
  • 6
  • 3
  • 3
  • 1
  • 1
  • Tagged with
  • 89
  • 45
  • 27
  • 25
  • 21
  • 17
  • 16
  • 16
  • 15
  • 13
  • 11
  • 10
  • 10
  • 9
  • 8
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Zajištění kvality služeb pomocí protokolu MPLS / Quality of service assurance using the MPLS protocol

Henzl, Václav January 2010 (has links)
The aim of this semestral thesis is to create a MPLS network model using OPNET Modeler program and consecutive simulation of this network behavior with focus on quality of service assurance. This project contains also theoretical introduction to the MPLS network problematic and quality of service assurance - hereafter it is focused on simulation and analysis of data flows in extended communication network model with focus on Voice Over IP parameters. This thesis is discovering attributes of MPLS with respect to network traffc.
42

Simulação e avaliação das tecnologias LTE e DSL como backhaul utilizando software OPNET

LINS, Silvia Cristina Feijó 20 December 2013 (has links)
Submitted by Cleide Dantas (cleidedantas@ufpa.br) on 2014-07-31T13:19:37Z No. of bitstreams: 2 license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) Dissertacao_SimulacaoAvaliacaoTecnologias.pdf: 1013915 bytes, checksum: da3b515d7ab4934a83707693639a07ea (MD5) / Approved for entry into archive by Ana Rosa Silva (arosa@ufpa.br) on 2014-09-05T12:15:02Z (GMT) No. of bitstreams: 2 license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) Dissertacao_SimulacaoAvaliacaoTecnologias.pdf: 1013915 bytes, checksum: da3b515d7ab4934a83707693639a07ea (MD5) / Made available in DSpace on 2014-09-05T12:15:02Z (GMT). No. of bitstreams: 2 license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) Dissertacao_SimulacaoAvaliacaoTecnologias.pdf: 1013915 bytes, checksum: da3b515d7ab4934a83707693639a07ea (MD5) Previous issue date: 2013 / A crescente demanda por capacidade vem levando os padrões de comunicação sem-fio a prover suporte para a coexistência de macro e pico células. O backhaul, conexão entre a rede de acesso e o núcleo da rede, é de grande interesse neste contexto devido aos diversos desafios técnicos e financeiros envolvidos ao tentar satisfazer o crescente tráfego dos usuários. Fibra óptica e micro-ondas com linha de visada são as opções mais amplamente adotadas para o backhaul de macro-células. Contudo, em muitas situações de interesse prático, estas não são factíveis devido aos altos custos e logística envolvidos. Este trabalho avalia o backhaul de pico-células, focando primeiramente na utilização de cobre como backhaul. O simulador OPNET foi utilizado para avaliar os requerimentos de backhaul para redes móveis em cenários específicos considerando garantir qualidade de serviço para os diversos tipos de tráfego envolvidos. Assumindo demandas de tráfego para LTE e LTE-Advanced, as tecnologias VDSL2 e G.fast são avaliadas e os resultados mostram que mesmo com uma grande demanda de aplicações de vídeo de alta definição, estas tecnologias podem acomodar o tráfego no backhaul de pico-células. VDSL2 é capaz de prover as taxas requeridas para cenários de pico-células LTE, mas não é capaz de acomodar tráfego LTE-Advanced típico. Por outro lado, considerando as taxas atingidas com a tecnologia G.fast, o tráfego backhaul para pico-células LTE-Advanced pode ainda ser entregue com garantias de qualidade de serviço. Neste trabalho também é proposta uma solução para simulação de cenários contendo redes de acesso heterogêneas considerando backhaul LTE sem linha de visada. São demonstrados também os resultados de simulações no OPNET com o backhaul LTE proposto para validar a solução proposta como capaz de caracterizar o tráfego de ambas as tecnologias WiFi e LTE na rede de acesso de acordo com o tipo de serviço. / The increasing demand for capacity has been driving the wireless communication standards to provide support to the coexistence of macro and small cells. The backhaul, which is the link between the radio access network and the backbone, is of particular interest due to the many involved technical challenges on keeping up with the user demand for bandwidth. Line-of-sight microwave radio and optical fiber are the preferred choices and widely adopted for the mobile backhaul (MBH) of macrocells. However, in many situations of practical interest, both options are not feasible due to cost and logistics. This work evaluates the backhaul of small cells, focusing on the adoption of copper pairs. Opnet was also used to evaluate copper MBH requirements in specific scenarios taking into consideration QoS provisioning. Assuming traffic demands for LTE and LTE-Advanced, VDSL2 and G.fast technologies are evaluated and the results show that even with a heavy load of video, these technologies can accommodate the small cell MBH traffic. VDSL2 is capable of delivering the required data rates for LTE small cell scenarios but not if considered LTE-Advanced traffic. Otherwise, if considered G.fast data rates, backhaul traffic for LTE-Advanced small cells can still be delivered by xDSL technology with QoS guaranteed. Also, this work enables the implementation of heterogeneous access networks scenarios considering LTE NLOS out-of-band backhaul. A solution of LTE backhaul implementation in OPNET is proposed and simulations are performed to validate such solution as a QoS-aware LTE Backhaul for WiFi and LTE radio access technologies.
43

Análise das tecnologias Bluetooth Low Energy e Zigbee em ambientes indoor para aplicações em internet das coisas

Sousa, Fernando Simplicio de January 2016 (has links)
Orientador: Prof. Dr. Ivan Roberto Santana Casella / Dissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Engenharia Elétrica, 2016. / Atualmente existem diversos padrões de redes sem fio destinados ao monitoramento de sensores em aplicações de redes sem fio. O Bluetooth Low Energy (BLE) e o Zigbee são duas tecnologias em destaques que estão sendo amplamente empregadas em Smart Grids e Internet of Things (IOT) e foram desenvolvidas para o envio rápido de pequenos pacotes de dados em baixa latência com suporte a elevados números de nós operando em baixo consumo de energia. A degradação da potência de um sinal de rádio transmitido por dispositivos Bluetooth Low Energy e Zigbee pode ser ocasionada pela existência de objetos (paredes, portas, janelas e vegetações) que interferem na livre propagação do sinal eletromagnético. O objetivo deste trabalho foi analisar e comparar, através de uma modelagem computacional, os impactos da atenuação do sinal de rádio de redes sem fio BLE e Zigbee operando em ambiente indoor. Foram medidos os valores da potência do sinal recebido, relação sinal-ruído, taxa de dados e taxa de erro de bit estimada para diferentes fatores de perda de percurso e considerado o efeito de Shadowing.A modelagem computacional foi desenvolvida com auxílio do software OPNET Modeler e contemplou algoritmos que simulam as camadas PHY, MAC e enlace do BLE e do Zigbee, que permitiu analisar o comportamento das redes sem fio durante as trocas de pacotes de dados entre os dispositivos móveis. Além das simulações computacionais, foram feitos experimentos práticos com redes sem fio BLE e Zigbee localizadas em ambiente indoor em zona urbana. Os resultados das medições em campo foram comparadas e configuradas no modelagem computacional. Desta forma, foram criados modelos computacionais do BLE e Zigbee que descrevem parcialmente os mesmos comportamentos das redes sem fio ensaiadas nos experimentos práticos, o que tornou os resultados das simulações da modelagem computacional muito mais realistas. Através destes novos modelos computacionais, foi possível medir, comparar e analisar o desempenho das redes sem fio BLE e Zigbee em ambiente indoor. e da taxa de dados e provoca um aumento de BER à medida que o receptor se distância do transmissor em uma rede de dispositivos BLE e a adição do Shadowing tornou os resultados da modelagem computacional muito mais realista. Além das análises, este trabalho contribuiu com detalhes do desenvolvimento da modelagem computacional do BLE e Zigbee que foi realizado.Os resultados das simulações demonstraram que o aumento do fator de perda de percurso causou uma redução significativa da potência de recebimento e da taxa de dados e provoca um aumento de BER à medida que o receptor se distância do transmissor em uma rede de dispositivos BLE e a adição do Shadowing tornou os resultados da modelagem computacional muito mais realista. Além das análises, este trabalho contribuiu com detalhes do desenvolvimento da modelagem computacional do BLE e Zigbee que foi realizado. / Currently there are different standards of wireless networks for the sensors monitoring in wireless networking applications. Bluetooth Low Energy (BLE) and Zigbee are two technologies widely used in Smart Grids and Internet of Things (IOT) and were developed for the fast sending of small data packets at low latency with high numbers of nodes operating in low energy consumption. The degradation of the power of a radio signal transmitted by a BLE and Zigbee devices can be caused by the existence of objects, walls, doors, windows and vegetation, that interfere with the free propagation of electromagnetic signals. The objective of this work was to analyze and compare, through computer simulations, the radio signal attenuation of wireless networks BLE and Zigbee when operating in indoor environment. The value of the received signal strength, signal to noise ratio, data rate and bit error rate estimated for different path loss factors were measured and considered the effect of shadowing. The computer simulations was developed with the help of OPNET Modeler software, which included algorithms that simulate the PHY, MAC and Link Layer of the BLE and Zigbee, which allowed analyzing the behavior of wireless networks for the exchange of data packets between the mobile devices. In addition to the computer simulations were made practical experiments with wireless networks BLE and Zigbee located in indoor environment in urban areas. The results of field measurements were compared and set in computational modeling. Thus they were created computer models of BLE and Zigbee that describe partially the same behaviors of the tested wireless networks in the field via practical experiments, which made the simulation results of computer modeling more realistic. Through these new computer models were possible to measure, compare and analyze the performance of wireless networks BLE and Zigbee in indoor environment. The results of computer simulations have shown that increasing the path loss factor caused a significant reduction in received power and data rate and causes an increased BER when the receiver is away from the transmitter in a network BLE devices and adding the shadowing in computer simulations became more realistic results. In addition, this work contributed to the development details of computational modeling of BLE and Zigbee.
44

Performance Analysis of AODV, DSR and OLSR in MANET / Resultatanalys av AODV, DSR och OLSR i MANET

Ali, Sajjad, Ali, Asad January 2010 (has links)
A mobile ad hoc network (MANET) consists of mobile wireless nodes. The communication between these mobile nodes is carried out without any centralized control. MANET is a self organized and self configurable network where the mobile nodes move arbitrarily. The mobile nodes can receive and forward packets as a router. Routing is a critical issue in MANET and hence the focus of this thesis along with the performance analysis of routing protocols. We compared three routing protocols i.e. AODV, DSR and OLSR. Our simulation tool will be OPNET modeler. The performance of these routing protocols is analyzed by three metrics: delay, network load and throughput. All the three routing protocols are explained in a deep way with metrics. The comparison analysis will be carrying out about these protocols and in the last the conclusion will be presented, that which routing protocol is the best one for mobile ad hoc networks. / In all the three scenarios of small, large and very large networks OLSR gives considerably less delay and high throughput as compared to AODV and DSR. OLSR outperforms AODV and DSR with prominent difference in delay and throughput. While the AODV puts low load on the network in large and very large networks. OLSR outperforms in our study, but it is not necessary that OLSR always perform better in all the networks, its performance may vary by varying the network. / sajj_ali2003@yahoo.com, asad322@gmail.com
45

Performance Evaluation of Real–Time Applications over DiffServ/MPLS in IPv4/IPv6 Networks / Utvärdering av prestanda för realtidsapplikationer över DiffServ / MPLS i IPv4/IPv6 Networks

Aziz, Md. Tariq, Islam, Mohammad Saiful January 2011 (has links)
Over the last years, we have witnessed a rapid deployment of real-time applications on the Internet as well as many research works about Quality of Service (QoS) in particularly IPv4 (Internet Protocol version 4). The inevitable exhaustion of the remaining IPv4 address pool has become progressively evident. As the evolution of Internet Protocol (IP) continues, the deployment of IPv6 QoS is underway. Today, there is limited experience in the deployment of QoS for IPv6 traffic in MPLS backbone networks in conjunction with DiffServ (Differentiated Services) support. DiffServ itself does not have the ability to control the traffic which has been taken for end-to-end path while a number of links of the path are congested. In contrast, MPLS Traffic Engineering (TE) is accomplished to control the traffic and can set up end-to-end routing path before data has been forwarded. From the evolution of IPv4 QoS solutions, we know that the integration of DiffServ and MPLS TE satisfies the guaranteed QoS requirement for real-time applications. This thesis presents a QoS performance study of real-time applications such as voice and video conferencing over DiffServ with or without MPLS TE in IPv4/IPv6 networks using Optimized Network Engineering Tool (OPNET). This thesis also studies the interaction of Expedited Forwarding (EF), Assured Forwarding (AF) traffic aggregation, link congestion, as well as the effect of various performance metrics such as packet end-to-end delay, packet delay variation, queuing delay, throughput and packet loss. The effectiveness of DiffServ and MPLS TE integration in IPv4/IPv6 network is illustrated and analyzed. The thesis shows that IPv6 experiences more delay and loss performance than their IPv4 counterparts. / Author (1): Md. Tariq Aziz Address: C/O: Murshed Gularm, Nykarleby Gatan 134, 16474 Kista, Stockholm, Sweden Author (2): Mohammad Saiful Islam Address: Minnervavägen 22B, 371 43 Karlskrona, Sweden
46

Study of inter-cell interference and its impact on the quality of video conference traffic in LTE Network / Study of inter-cell interference and its impact on the quality of video conference traffic in LTE Network

Islam, MD. Jhirul, Chowdhury, Mohammed Nazmul Haider January 2013 (has links)
While inter-cell interference coordination (ICIC) for the downlink and uplink of multi-cell systems (in general) and orthogonal frequency division multiple access (OFDMA) networks (in particular) have been extensively studied, the study of the impact caused by inter-cell interference with video conferencing traffic has received less attention. The consideration of video conferencing traffic is essential for analyzing the overall performance analysis of inter-cell interference in LTE networks, and in particular for the evaluation of the video conferencing traffic. In LTE networks, the same frequencies can be used in several adjacent cells. This means that in practice every cell may have other cell nearby whose radio transmissions may interfere with the own signal. In this paper, we report a comprehensive analysis on the performance of video traffic considering the inter-cell interference impact in LTE network. The interference patterns are configured by using the OPNET simulator for a given set of parameters, such as cell configuration, user configurations, and traffic models. The interference pattern is used to study the performance of video conferencing traffic in LTE network for realistic deployments. We, present a detailed description of the way to model the network in OPNET platform considering the inter-cell interference. In order to use the suggested network model in OPNET platform three network scenarios are configured. They are fully overlapped, half overlapped and no frequency overlapping. These scenarios are configured in such a way to show how the video traffic is impacted when the network load increases. The thesis shows that the video conferencing traffic experiences more delay and loss when fully overlapped frequency is used in the adjacent cell on LTE network. / Moammed Nazmul Haider Chowdhury C/o,Huq M A Visattravagen 30 LGH 1010 Huddinge 14150 Mobile:+46760996255 Mob:
47

End-to-End Delay Performance Evaluation for VoIP in the LTE network

Masum, Md. Ebna, Babu, Md. Jewel January 2011 (has links)
Long Term Evolution (LTE) is the last step towards the 4th genera-tion of cellular networks. This revolution is necessitated by the un-ceasing increase in demand for high speed connection on LTE net-works. This thesis mainly focuses on performance evaluation of end-to end delay (E2E) for VoIP in the LTE networks. In the course of E2E performance evaluation, simulation approach is realized using simulation tool OPNET 16.0. Three scenarios have been created. The first one is the baseline network while among other two, one consists of VoIP traffic solely and the other consisted of FTP along with VoIP. E2E delay has been measured for both scenarios in various cases under the varying mobility speed of the node. Furthermore, packet loss for two network scenarios has been studied and presented in the same cases as for E2E delay measurement. Comparative performance analysis of the two networks has been done by the simulation output graphs. In light of the result analysis, the performance quality of a VoIP network (with and without the presence of additional network traffic) in LTE has been determined and discussed. The default parameters in OPNET 16.0 for LTE have been used during simulation.
48

Implementation Of Wireless Channel Propagation Models In OPNET

Guo, Zhijuan January 2013 (has links)
In recent times, there has been a significant amount of research regarding the physical layer of wireless communications . The part of the physical layer, which cannot be ignored, is channel propagation. Different environments have different channels. Path loss, slow fading, fast fading and multipath fading are all involved in decisions regarding the condition of the channel . Based on related research, a number of empirical channel models are put forward to simulate a real environment with regards to communication and there are some simulation softwares that are able to implement those different channels. These include Matlab which is regarded as the best simulation software for the physical layer in wireless communication. OPNET is another network modeling simulation software, which could implement the entire process of the network communication, which Matlab is not able to complete . The network layer of OPNET is very mature and has the ability to implement different routing protocols. However, the description of the physical layer in OPNET is poor and there is only simple path loss model in pipeline modeling in OPNET. Thus, the objective of this thesis is to implement different channel models in OPNET and to make it capable to simulate in as close a manner as possible to a real environment.
49

Implementace parametrických modelů závislých na okamžitých vlastnostech síťového provozu v simulačním prostředí OPNET Modeler / Implementation of parametric models dependent on instantneous values of network traffic in OPNET Modeler simulation environment

Šibík, Štefan January 2008 (has links)
The aim of this diploma thesis was to create an own DiffServ domain model, which is supplemented with stations generating various type of network traffic and implementation of token-bucket mechanism in router´s process model in Opnet Modeler simulation environment. DiffServ domain is made up from two edge and two core routers and includes servers and client stations generating VoIP, FTP, HTTP and database access traffic. It is described a process of distribution of traffic into different classes on edge routers of DiffServ domain along with assurance of separate handling with usage of an Assured Forwarding PHB mechanism. In point of differentiated packet processing is process model completed with generating of various statistics. The process of their creating is used to check a dropper activity, which is implemented together with token-bucket mechanism on ARP layer of the router. The functionality of the model is verified by simulation.
50

Analýza LAN sítě s následnou simulací v prostředí Opnet Modeler / Analysis of LAN Network followed by Simulation in Opnet Modeler Environment

Skopal, Jakub January 2009 (has links)
This thesis deals with the exploration of possibilities of LAN analysis with the use of the hardware analyzer Finisar TGHs from the Finisar Corporation Company. As a monitored network was choosed the local computer network in the laboratory PA-249 at the Department of Telecommunications, which is located at the Faculty of Electrical Engineering and Communication, Brno University of Technology. All results acquired from the complex long-term monitoring of the choosed LAN network are described in this thesis. Further, the thesis is focused on the simulation and analysis of the model of this network that was created in the simulation environment Opnet Modeler. The data obtained from the real LAN monitoring were used as a basis of an operating simulation of the transmission abilities and features of the real LAN network. The last part of the thesis describes the verification of the transmission capabilities and characteristics of the real LAN. Verification was performed in Opnet Modeler, where the network has been analyzed in detail.

Page generated in 0.017 seconds