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Increasing the efficiency of the handover in real network environment
Michalec, Richard ; Sobotka, Jiří (referee) ; Vajsar, Pavel (advisor)
The aim of this work is to study methods of handover used in WiMAX and WLAN networks, next suggest the posibility of simulation methods for WLAN handover in the simulation environment OPNET Modeler. This work is focused primarily on obtaining the information about neighboring AP and subsequent selection of a new AP using such information. The work describes in detail each processes solutions that are used to implement newscanning methods
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Administration and configuration of simplified database QoS MIB
Macura, Miroslav ; Matocha, Tomáš (referee) ; Hošek, Jiří (advisor)
The main aim of this work was to study the issue of the SNMP protocol and MIB database in order to focus on management and configuration of MIB database using the SNMP protocol. The Master's thesis in detail describes especially creating a communications model of the Manager - Agent type in an OPNET Modeler. In this modeling tool we created exchange of information from the side of the Manager to the side of the Agent via SNMP packets. The Master's thesis is mainly focused on the creation of the SNMP packet according to defined rules, then on reading of information from the MIB database on the side of the Agent and saves this information to the Manager’s MIB database. Exchange of informations is realized via the messages of type GetRequest, GetNext and GetResponse. These models are programmed in language C/C++ and then implemented into the environment of OPNET Modeler.
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Design and implementation of model architecture of MIB system database
Mikulica, Vladimír ; Hošek, Jiří (referee) ; Molnár, Karol (advisor)
The submetted work deals with the systems design and the implementation of the model database MIB. The work is the introduction into the protocol SNMP (Simple Network Management Protocol) and the database MIB (Management Information Base), which describes in detail branch MIB II. This branch is the current standard for the management of objects using SNMP. Consequently, there are explained different data types that the MIB database uses. Furthermore, the work describes the procedures for the design of the database MIB in the language of ASN. 1 according to RFC 2233 and the subsequent transfer of the MIB database, available through the compilers into the langure C. In the following chapters of the work, each of the models that were created in the simulated environment OPNET Modeler during the implementation of a comprehensive simulation scenario are documented more in detail. The above mentioned parts implement the communication between the manager and the agent. The state machine and the individual blocks of the model are described so that it could be later re-assembled by other candidates.
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Quality of service assurance using the MPLS protocol
Henzl, Václav ; Novotný, Vít (referee) ; Hošek, Jiří (advisor)
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.
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Analysis of delay dependence of modern communication services and channels, QoS optimization
Rozman, Jiří ; Szőcs, Juraj (referee) ; Endrle, Pavel (advisor)
The main aim of this thesis is to familiarize with options of services using real-time data transfer in wireless networks. Theoretical part presents wireless network based on IEEE 802.11 standard and its practical use. Large part is focuses on 802.11e standart, that provides support for quality of service in wireless networks. Furthemore this thesis deals with transport and applicaton protocols supporting multimedia streaming over computer network. Second chapter is focused on analyzing real computer network with purpose in measuring parametrs influencing quality of service such as bandwith, delay, jitter and loss. Last part deals with the design of wireless network in OPNET Modeler enviroment with focus on simulating parameters that influence quality of service.
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Fault recovery in data networks
Trávníček, Michal ; Martinásek, Zdeněk (referee) ; Mácha, Tomáš (advisor)
The purpose of the bachelor’s thesis was to explain the basic principles and technologies for ensuring reliable and effective routing within networks when a link failure. This is with minimal effect to the quality of service. The focus was on mechanisms ensuring the quality of services within the network, especially differentiated services and the both groups of dynamic routing protocols – distance vectors and link state protocols. On the basis of obtained knowledge, the simulation has been designed in OPNET Modeler. It simulated routing of routing protocols RIP and OSPF of networks without any failure. The next simulations containted the link failure and the link recovery. Then the network with DiffServ was designed. It filtered data packets according to used ports and protocol and it added a label to packet with a priority for the certain service. The attention in the network was focused on the VoIP service and its parameters, such as jitter and end-to-end delay. It has also monitored the value of dropped traffic. It simulated the networks with the link failure and the link recovery. The results were compared to the network with no QoS and network with QoS but no failure.
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Wireless and mobile UMTS networks simulation using QoS
Zapletal, Lukáš ; Vychodil, Petr (referee) ; Vymazal, Michal (advisor)
Diplomová práce je psána v angličtině a věnuje se standardu IEEE 802.11e, obsahujícím podporu kvality služeb a taky pojednává o kvalitě služeb QoS (Quality of Service) v systému UMTS. Rozebrány jsou hlavní teoretické pilíře daných mechanizmů a praktická část se zabývá simulacemi síťových modelů. Standard 802.11e objasňuje propojení vrstev na fyzické úrovni a zmiňuje metody přístupu k přenosovému médiu DCF, PCF, HCF, EDCA, HCCA. Dále přístupové kategorie a také odlišnosti v MAC podvrstvě, je rozebrána problematika při přenosu prioritních dat na základě identifikátorů. Vzpomenuta je taky struktura formátu rámce a techniky s rozprostřeným spektrem. Časové limity pro doručení prioritních dat a požadavky kladené na tyto data je možné snadno srovnat v tabulkách. Problematika kvality služeb je velice komplexní záležitost, nicméně jsou rozebrány základní klíčové parametry jako koncové zpoždění, jitter, zahazování dat, propustnost, velikost front a hodnota MOS. Zmíněny jsou i mechanizmy integrovaných RSVP a diferencovaných služeb pro zajištění QoS. U systému třetí generace UMTS je objasněna architektura a společná kooperace se systémem GSM. Vzájemné propojení obou sítí je zřejmé z obrázků. Zvýšený zájem je věnován vrstvovému modelu a funkcím RRM pro zajištění QoS. Objasněny jsou různé druhy předávání hovorů, tzv. Handover Control a funkce Admission Control. Rozebrány jsou jednotlivé třídy provozu Conversational, Streaming, Interactive a Background. Praktická část se odehrává v simulačním prostředí programu OPNET Modeler. Byly vytvořeny dva modely s různými scénáři pro srovnání zajištění QoS. Model objasňující princip standardu IEEE 802.11e obsahuje dvě bezdrátové sítě s přístupovými body a stanicemi, na kterých jsou sledovány simulace s různým zatížením přenášených dat. Pro porovnání výsledků je zkoumán rozdíl při použití metody HCF v síti s podporou QoS. Model UMTS sítě obsahuje základnové stanice Node B s možností vysílání do tří sektorů. Mobilní účastník pohybující se po trajektorii představuje princip funkce Softer Handover. Konfrontace mezi scénáři je zastoupena kompresí záhlaví pomocí funkce PDCP a rozlišení Type of Service. Obzvláště je sledováno chování prioritních dat hlasu a videa u obou sítí. Naměřená data zastupují grafy a průběhy výsledních charakteristik. Analýza diskutuje odlišnosti u sítě bez podpory a s podporou kvality služeb. Rozdíly jsou porovnány a vyhodnoceny dle metodiky QoS. Součástí práce je i řešení problémů při návrhu UMTS sítě a podány jsou taky užitečné tipy a návrhy na jejich odstranění. Projekty v simulačním softwaru jsou popsány dle postupu vyhotovení, avšak hloubka podrobností je potlačena. Detaily nejsou rozebírány, protože se očekává pokročilá znalost mechanizmů a jistá dávka zkušeností s programem.
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Effect of softhandover function on effectivity of using radio sources in UMTS
Plhák, Jan ; Lambertová, Petra (referee) ; Novotný, Vít (advisor)
Bachelor’s thesis is focused on soft handover procedure in the UMTS network and its impact on the function of this network. Soft handover function allows continuous transfer of data flows, when the mobile station is crossing the border between areas which are controlled by different basic stations. This function has also impact on the performance and capacity of the whole network. This thesis describes the features of the UMTS network, soft handover principles, differences between various types of handovers and focuses on the mechanisms of the soft handover in detail. There have been several scenarios of handover procedure created in network simulation software and have been confirmed features of this function, that allows use of the lower transmission powers. On the other hand the soft handover burdens radio resources more than hard handover because of multipath propagation of the signal. To achieve the greatest soft handover gain, parameters of the network have to be set properly.
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Generation of data units in OPNET Modeler environment
Mikulica, Vladimír ; Skořepa, Michal (referee) ; Hošek, Jiří (advisor)
This dissertation deals with the generating of data units at different levels of TCP/IP network model in OPNET Modeler environment. A part of the dissertation is a brief introduction to the simulation environment OPNET Modeler where important components of this comprehensive simulation software are elucidated. The structure of my dissertation reflects individual layers of the model TCP/IP, whereas the function of the process model OPNET Modeler and the data unit used at corresponding levels of TCP/IP is always described. Particular parts of communication models that were created in the simulation environment OPNET Modeler at selected layers of the network model TCP/IP are closely documented in each chapter. Relevant scenarios are described in such a way that they can be later re-arranged by eventual customers.
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Verification of the statistical reliability of simulation results in OPNET Modeler environment
Fördős, András ; Vajsar, Pavel (referee) ; Hošek, Jiří (advisor)
Project is focused to verify the credibility of the results of statistical simulation in the surround of OPNET Modeler. At the beginning of the project is a short introduction to the problematic of OPNET Modeler. It describes the basic concepts of mathematical statistics, data types and some basic statistical charakteristics. In the project was created model of LAN network, were set up three different types of runs and several monitored statistics. In this project are listed setting of the model, startup parameters of some runtime simulations, prefered variety of statistics and the possibility to display final results of statistics. Description of options displaying final results of statistics is supplemented by model characteristics. Created model was further extended and modified. Have been added network services, has changed the number of nodes and the duration of the simulation. Results of analysis of the original scenario are compared to the results of a modified scenario, which are scheduled. At the end of this project are obtained result, recommended way and form of displaying basic statistics and advice on the number of simulation runs needed to obtain reliable results.
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