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An Architecture for Global Distributed SIP Network Using IPv4 Anycast
Anděl, Ladislav ; Polívka, Michal (referee) ; Kovář, Petr (advisor)
Tato diplomová práce se zabývá metodami pro výběr nejbližší RTP proxy k VoIP klientům s použitím IP anycastu. RTP proxy servery jsou umístěny v síti Internetu a přeposílají RTP data pro VoIP klienty za síťovými překladači adres(NAT). Bez zeměpisně rozmístěných RTP proxy serverů a metod pro nalezení nejbližšího RTP proxy serveru by došlo ke zbytečnému poklesu kvality přenosu médialních dat a velkému zpoždení. Tento dokument navrhuje 4 metody a jejich porovnání s podrobnějšími rozbory metod s využitím DNS resolvování a přímo SIP protokolu. Tento dokument také obsahuje měření chování IP anycastu v porovnání mezi metrikami směrování a metrikami časovými. Nakonec dokumentu je také uvedena implemetace na SIP Express Router platformě.
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Implementation of quality of service in a converged network
Zvolenský, Daniel ; Kovář, Petr (referee) ; Škorpil, Vladislav (advisor)
The point of this work is the creation of IP network with a proper topology, in Network Simulator version 2, where voice packet stream with recommended compresion by G.723 standard and real-time video by H.263 standard will be simulated. Theoretical part of this work consists of convergence of nets with an implementation of Quality of Services description. In practical part of this work is identification with bacis commands in program Network Simulator 2, which make possible simulation of network behaviour.
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JavaME Group SMS Messaging Interface
Kubina, Tomáš ; Kubánková, Anna (referee) ; Kovář, Petr (advisor)
This Diploma Thesis have been describing possibilities of Wireless Messaging API, which are used for applications handling with Short Messages. It have been describing basics of programming language JavaME, basics of formating and sending SMS, detailed analysis of Wireless Messaging API, application, which is part of my diploma thesis and finally Security Politics of JavaME programming language.
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Optimization of UMTS access network
Havlíček, Karel ; Kovář, Petr (referee) ; Novotný, Vít (advisor)
This master’s thesis deals with a UMTS radio access network optimization, containing radio interface analysis, services and procedures description, ways to correct parameters calculations and settings and other issues necessary for a correct access network operation. The goal is effective network operation, minimum costs and maximum performance and flexibility of the network. The optimization during system operation is important because of the system character. The UMTS system uses the WCDMA technology, where particular users share the same frequency band and they are distinguished from one another via code sequences. The capacity of such a system is then given by the interference level - each particular user increases the interference level by the value corresponding to his transmit power. The maximum cell capacity is determined by the maximum interference level at which users can still operate with required services, so it is related not only to the number of users, but also to their bit rate. The optimization allows effective usage of the system for different services with different requirements. The main optimization tool is the radio resource management, containing number of algorithms, such as admission control, which decides the acceptance or rejection of a new user demanding certain service, power control, which ensure that users transmit with a minimal power sufficient for required service, handover and cell selection algorithms etc. The major parameter used by these algorithms is a cell load factor, which is related to the interference level margin. There are several methods for the load factor estimation and some of them are described in this work. Some other optimization techniques are mentioned here, too. This work also contains a laboratory exercise proposal for radio resource management introduction using the OPNET Modeler network simulation tool.
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Multimedia Services in Mobile Networks
Kovář, Petr ; Molnár, Karol (advisor)
Long time ago, there were developed methods which can allow fast exchange of information at the longest distance possible. Until recent time, the possibilities of long way communications were very limited. There were technological and financial limitations mainly. With telegraph, telephone and the newest – computer networks invention, the telecommunication services became cheaper and much more comprehensive. With accession and high scale spread of internet, the role of communications is much more important. The most actual trend is mobile internet and connected multimedia networks and their instant accessibility from anywhere. On the first side there are classical telecommunication networks as GSM, UMTS, on the other side there is very strong alternative in shape of WiMAX and WiFi networks combination. For the usage of multimedia services in that networks is very important to handle their prefferization over other traffic, which is very difficult task even on wireless media. For the finding of new processes and methods, which can allow it, there is, at fist, the need for highly accurate and authentic mathematical models. In this doctoral thesis is mapped actual state of the art and proposed the new mathematical model of Distribution Coordination Function, which is much-frequent used as access method in 802.11 networks, Wi-Fi.
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VoIP Security
Černý, Michal ; Číka, Petr (referee) ; Kovář, Petr (advisor)
Internet telephony becomes still more popular option to common telephone service. Reason may be it's price as well as availability. With growing popularity grows the risk of unauthorized use of transferred data too. There are several ways to secure VoIP communication. This bachelor's thesis talk about one of many, which is use of Secure RTP. There will be made it's implementation in the software telephone exchange Asterisk and tested functionality by trial talks and analysis of network traffic as well.
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Progress of welding in shipbuilding
Urban, Václav ; Kubíček, Jaroslav (referee) ; Kovář, Petr (advisor)
This work deals with the methods of welding in shipbuilding, summarises the basic techniques used for welding of the SAW, MAG, MIG, TIG, laser, Laser-Hybrid. It describes the properties of welded material. Especially the materials HY80 and HY100. It follows from the filler materials. In particular materials Spoolarc 95 and 120. Particular emphasis is placed on the method of Laser-Hybrid, its properties and use in shipbuilding. Finally, describes the method of welding aluminium using FSW, preparation of welded surfaces and producting of sandwich panels.
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Converged solution of speech services
Mácha, Tomáš ; Kovář, Petr (referee) ; Novotný, Vít (advisor)
Development in VoIP technology is connected with the rapid growth of quality and data rate of the Internet connection. The application of the VoIP technology has become one of the key areas in telecommunication and networking. The main task of this thesis was to explore the questions of IP telephony and voice transmission over data networks according to H.323, SIP and Cisco architectures. Next focus was on designing and implementing experimental workplaces of mentioned architectures and their converged solutions. The purpose of the first chapter is to introduce the theory background of architectures required for implementation of real-time services in data networks and their comparison. The key objectives of the second and third part are to design and implement experimental workplaces containing signaling and proxy servers and hardware or software IP phones of several architectures. Illustration examples of different network topologies are included to demonstrate designed and realized VoIP solutions. Several tests of established communication are done using a packet analyzer. These tests examine duplex data transmission over IP. This article also contains two laboratory exercises designed according to gained practical experiences. The laboratory exercises provide an overview of theory and clearly indicate the possibilities of IP telephony.
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Qualification of welding procedure - WPQR
Houra, Milan ; Kubíček, Jaroslav (referee) ; Kovář, Petr (advisor)
The project developed within the bachelor's degree field of B-STG Engineering technology is focused on developing protocols for a preliminary welding procedure specification for a given drawing pWPS weldments. Subsequent to preliminary approval of these protocols are implemented protocol for qualification of welding procedures WPQR. This WPQR protocol is drawn up for a similar award has developed pWPS protocols. The most important parts of the protocol WPQR are destructive and nondestructive tests, which are discussed from both theoretical and practical in the field. At the end of the WPS is the resulting log with a direct link to WPQR protocol is implemented and appreciation of the control tests.
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