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Anonymous communication in Internet environment
Pajtinová, Mária ; Malina, Lukáš (referee) ; Hajný, Jan (advisor)
Master´s thesis focuses on certain possibilities of how user can anonymously commununicate through the Internet. There are described following anonymous programs: TOR, JAP, I2P and CyberGhost, which allow user to hide his own identity to other IP address. Subsequently, measurements from different technologies are made by anonymous program TOR for calculate transmission speed.
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Data transmission in mobile networks
Bílek, Petr ; Molnár, Karol (referee) ; Havelka, Dušan (advisor)
The Bachelor’s thesis deals with mapping and usage of mobile networks of data transfers. It describes every particular generation of networks and technologies that they can use. This thesis is divided into two main parts, theological and practical. In the first part, the technologies of the second and third generation currently used for data transfer in mobile networks are described there. This concerns especially GPRS, EDGE and UMTS services. The thesis focuses on modulations used for these technologies, together with the coding and bit rates possible. It compares their advantages and disadvantages and presents their utilization among national operators. It also tries to sketch out the way the data services of mobile networks will proceed. The second part of the thesis is also divided into two parts. The first one is the simulation of the UMTS network with the assistance of the OPNET Modeller 14.5 environment. In this case, the thesis aims at two important characteristics - such as the dependence on the bit rate and distance of the primary station, and dependence on the bit rate and total load of the whole network. Both characteristics are observed mainly because of the bit rate and power characteristics. It describes objects and funcions of the OPNET environment. The next part in the practical section is the factual measurement of the Internet 4G service, provided by T-Mobile operator. The thesis focuses here on the presentation of the outcomes which were accomplished by the practical measurement of that service. The end of this thesis is dedicated to the comparasion of simulated outcomes with the outcomes practically measured, and to the conclusion of the results emerged from them.
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Analysis of the effect of delay and window size on TCP connection efficiency
Kavický, Martin ; Komosný, Dan (referee) ; Molnár, Karol (advisor)
Content of master’s thesis is description field of Sliding window and it’s expansion algorithms, witch are Slow start, Congestion avoidance, Fast Retransmit and Fast Recovery algorithm. Thereinafter is described creation of model in Opnet Modeler’s simulation area. In this simulation area was analyzed reactions of average transfer speed onto variance of data size, lost ratio, latency in short and long time slot and variance of receiver’s buffer size. In last section of this document is method design witch makes it possible of transfer speed control through the use of receiver’s buffer size dynamic setting.
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Free-Space Optics data link
Šála, Jakub ; Číž, Radim (referee) ; Šporik, Jan (advisor)
In this thesis, shows a current issue for free space optics, limiting their use in practice with regard to the availability and reliability. They conducted measurements on wireless optical links and the observed values is calculated by the availability of the connection. Subsequently, measurements are performed on alternate versions of wireless and copper connections. Observed values were compared with a wireless optical link. It is made of optical design of wireless connections at home.
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The transmission speed enhancement techniques in TKR
Šťovíček, Petr ; Křepelka, Václav (referee) ; Filka, Miloslav (advisor)
The purpose of this work is to assess and propose possible methods for increasing the transmission speed of the cable television distribution, concretely the UPC network in Brno. The first part of work collectively processes general knowledge and gives the reader into the issue. After that follows an analysis of TV cable networks UPC in Brno, especially view of data transmission. After familiarization with the physical aspect of the network is described data communications itself, including standard DOCSIS, respectively EuroDOCSIS. Particular attention is paid to factors that have effect on data transmission and speed. Benefit is the calculation of dividing ratio in different parts of the network and compared with the real load. As far as possible in the given work results of measurements with regard to the quality of the network. The last part is about how to increase speeds. Perspective solution is mainly a technology which is based on standard EuroDOCSIS 3.0, which introduces the concatenation of individual channels. Result of made tests of first cable modem EuroDOCSIS 3.0 confirms the very high speeds and currently preparedness for other major step in so long development of TV cable network.
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Net for communication in a company
Sychra, Jakub ; Vaněk, Jiří (referee) ; Špinka, Jiří (advisor)
This work deals with accessible communications technologies and their possible usage in firms. It is necessary to have a survey about types and trends of communications technologies at proposal of communications network. It is important to choose the combination that is suitable with its reliability, achievement and price.
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Digital Signal Processor for Handheld RFID Reader
Benetka, Miroslav ; Zamazal, Michal (referee) ; Šebesta, Jiří (advisor)
This diploma thesis deals with design and realization of a module for a digital signal procesor, for handheld RFID reader working in UHF band. It utilises a special chip EM4298 for RFID signals processing. Module is controlled by the microcontroller ATmega32L, which communicates with the PC through USB bus. Settings in EM4298 is made by a service program which processes received identifying data obtained from tags. Source codes for microcontroller are created in AVR Studio 4.13 program. Source codes for microcontroller are created in C++ Builder 6.0 program. Further thing is Desing and realization of analog interface and a UHF transceiver for wireless communication with tags. A Webench program was used for the analog interface design, which is freely available on the internet. For verification of parameters of the analog interface it was used PSpice 10.0 program. The UHF transceiver is build-up with a MAX2903 chip (transmitter) and AD8347 (receiver) and transmitting and receiving antennae.
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