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Improvement of Bit Error Rate in Free Space Optical Link
Novák, Marek
The article describes an inovative bit error rate reduction technique principle and its practical implementation. The design is implemented in an FPGA and can be combined with other more conventional BER reduction techniques. The presented approach benefits from properties of an optical channel which a general RF channel does not have.
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Measurement of diversity broadcasting in DVB-T2 standard
Koblischka, Vítězslav ; Kratochvíl, Tomáš (referee) ; Polák, Ladislav (advisor)
This bachelor thesis compares standards for digital and terrestrial television broadcasting of first-generation DVB-T and second-generation DVB-T2. It focuses particularly on the impact of interference in transmission media simulated by transmission channels for fixed, portable and mobile reception of terrestrial digital signal. Furthermore, the thesis compares SISO broadcast with the diverse MISO broadcast in DVB-T2 standard and evaluates the impact of the mode on error rate depending on the selected transmission channel and systems parameters that were used.
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The audit methology of optical networks
Štěpán, Petr ; Münster, Petr (referee) ; Reichert, Pavel (advisor)
This work deals with summary of optical system audit in the terms of all layer of the reference model ISO/OSI. Introduction of the work focuses on exploring issues of management networks control, the description of ISO/OSI model and explanation of the terms QoS and SLAs. The description of the optical fiber transmission follows after that. The characteristics of the waveguide and optical communication system components with regard to its reliable operation and management are analyzed. Some major types of optical networks are described. Following section contains a description of methods used in the audit, further the methods for measuring physical, connection and network layer of the reference model are discussed more thoroughly. The work also contains a partial analysis of the audit of the physical layer of the selected section of the Brno academic network optical line. Of all these methods for networks control the final audit report for the optical network with selected limits is compiled as a conclusion of the work.
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LDPC codes
Hrouza, Ondřej ; Šedý, Jakub (referee) ; Šilhavý, Pavel (advisor)
The aim of this thesis are problematics about LDPC codes. There are described metods to create parity check matrix, where are important structured metods using finite geometry: Euclidean geometry and projectice geometry. Next area in this thesis is decoding LDPC codes. There are presented four metods: Hard-Decision algorithm, Bit-Flipping algorithm, The Sum-Product algorithm and Log Likelihood algorithm, where is mainly focused on iterative decoding methods. Practical output of this work is program LDPC codes created in environment Matlab. The program is divided to two parts -- Practise LDPC codes and Simulation LDPC codes. The result reached by program Simulation LDPC codes is used to create a comparison of creating and decoding methods LDPC codes. For comparison of decoding methods LDPC codes were used BER characteristics and time dependence each method on various parameters LDPC code (number of iteration or size of parity matrix).
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CDMA Network Capacity
Pasečný, Jan ; Kejík, Petr (referee) ; Hanus, Stanislav (advisor)
The Bachelor thesis deals with determining which factors influence the capacity of CDMA network. This type of network is now being used worldwide due to its huge increase in capacity when compared to other transmissions systems. The work contains summary of basic parameters of single-cell and multi-cell systems with reference to the capacity. Obtained results are assesed and compared at the end of the work.
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Signal processing in ZigBee system
Miloš, Jiří ; Bradáč, Zdeněk (referee) ; Hanus, Stanislav (advisor)
Master's thesis The Signal Processing in ZigBee System is focused on properties of Physical Layer of ZigBee (standard IEEE 802.15.4 - 2003). The work consists of three parts. The first part contains common view on using and properties of ZigBee. The next part focuses on the Medium Access Control Layer and in detail on the Physical Layer. There described signal processing in the Physical Layer in individual radio bands. The last part of the project contains the process of modeling in the MATLAB for both models of system ZigBee (bands 868/915 MHz and 2450 MHz). The last part of thesis deals with the simulations of BER depending on Carrier-to-Noise Ratio. Also examined the coexistence of systems operating in the same or a nearby frequency band. Based on the results of simulations there are given recommendations for the use of the ZigBee system in minimizing BER.
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Co-existence of the still used and upcoming digital terrestrial television and mobile communication services
Plaisner, Denis ; Kratochvíl, Tomáš (referee) ; Polák, Ladislav (advisor)
This work deals with exploring, measuring and evaluation of possible coexistence scenarios between terrestrial digital TV (DVB-T/HT2) and mobile wireless services (GSM, LTE), which can occur in a shared RF frequency bands The DVB-T, DVB-T2 and LTE standards are briefly described. RF band, where these systems are operated, are outlined too. . There are defined different coexistence scenarios. For the measuring, monitoring and evaluation of these scenarios, an appropriate laboratory workplace is proposed and realized. Results from the measurements show various influence of interfering mobile services on the interacted DVB-T/H system, depending on the considered coexistence scenario.
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Laboratory workplace for measuring performances of DVB-T2/T2-Lite
Krejčíř, Dominik ; Kufa, Jan (referee) ; Polák, Ladislav (advisor)
This thesis deals with proposal and realization an appropriate measurement workplace to measure performances of DVB-T2 and DVB-T2-Lite. Both systems for terrestrial digital video broadcasting are described. It is possible to measure objective parameters and evaluate the quality of DVB-T2/T2-Lite signal subjectively. The proposed concept was verified by a set of experimental measurements, which is divided into four scenarios. The measurement focuses to parameters of Set-Top-Boxes. The measurement allows to test and compare Set-Top-Boxes.
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Digital terrestrial television broadcasting DVB-T/H and DVB-T2
Pospíchal, Martin ; Ulovec,, Karel (referee) ; Kratochvíl, Tomáš (advisor)
Master's thesis compares the standard for digital terrestrial television broadcasting of the first generation DVB-T/H and the second generation DVB-T2 with particular emphasis on the modulator, a security channel interference, the signal from the transmitting environment itself and the modulation signal. The following description of specific models of transmission channels for fixed, portable and mobile reception of digital terrestrial signal. Comparison with the particular relates of the transmission parameters for different types of reception of digital terrestrial television with achieving efficiency and effectiveness of transmission at the level of laboratory measurements and computer simulation.
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