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Assignment of the OFDM signal cyclostationary detector behaviour.
Lehocký, Jiří ; Šimša, Jan (referee) ; Šebesta, Vladimír (advisor)
Master’s thesis belongs to the Cognitive radio network sphere. These networks utilize frequency spectrum more effectively than networks used in present radio communications. The Cognitive radio concept makes coexistence of classic and cognitive radio networks possible. Attention is aimed at spectrum sensing as the key task of the Cognitive radio. Main properties of the cyclostationary detector, as the detector, that reaches high probability of the detection at a very low signal to noise ratio with apriori knowledge of the transmitted signal's cyclic frequency, are examined in this paper. The OFDM signals, that inherit cyclostationarity from cyclic prefix, used in the real systems have been chosen for testing the properties of the detector. The influences of decimation and multipath propagation on the probability of detection are quantitatively expressed. The optimal values for the weights of the multicycle detector are determined.
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Channel estimation in CDMA systems
Kadlec, Petr ; Prokopec, Jan (referee) ; Kejík, Petr (advisor)
The subject of this work deals with the problem of channel estimation for CDMA systems. This method of multiple access when individual users share the same full bandwidth simultaneously and are differentiated with any of pseudorandom sequences, is now the most perspective method. That is proved by its wide implementation in mobile networks of the third generation and higher systems. This work describes basic theory principles of spread spectrum, above all DS-CDMA (Direct Sequence-CDMA) and furthermore some phenomena of radio wireless channel that affect changes in transmitted signal in its way from transmitter to receiver. Terms of fading, multipath propagation, loss, refraction, scattering of the wave and Rice and Rayleigh probability density functions are mentioned. The third chapter deals with yet known and used capabilities of channel estimation. Differences, advantages and disadvantages of so-called blind estimation or training-based estimation are discussed. Two algorithms: LS method and sliding correlator are analyzed in more detail. There is also description of their simulations in Matlab and some results of these simulations are discussed. The last chapter deals with comparison of main characteristics and achievable accuracy of wireless channel impulse response estimation by both methods, and their possible utilization in real live.
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Analysis of the transmission in the mobile digital audio broadcasting
Kresta, Daniel ; Ulovec,, Karel (referee) ; Kratochvíl, Tomáš (advisor)
This thesis deals with an analysis of a system called Digital Audio Broadcast and describes its mathematical model created in MATLAB program. In the first part basic blocks of a transmitter and a receiver are analyzed along with their principles. Then different types of transmission channels for static, portable and mobile receivers are described. The second part contains description of the DAB mathematical model itself. Individual blocks are described in the order of the DAB signal path, from the transmitter through the transmission channel to the receiver side. In this part the graphical user interface is also described. In the final part the results of experimental measurements and simulations are presented.
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Performance analysis of SFNs transmitters of DVB-T2
Bárta, Vojtěch ; Miloš, Jiří (referee) ; Polák, Ladislav (advisor)
The diploma thesis deals with the design and analysis of Single Frequency Networks (SFNs) transmitters for Digital Video Broadcasting – second generation of the Terrestrial (DVB-T2). In this thesis, the software of the Czech company CRC data is used. Main attention is focused on the SFN Networks computational system for the analysis and design od DVB-T2 SFN networks, in which a series of simulations of the transmitting Multiplex 21 (CH26) have been performed. The simulation-based results are used to identify locations with lower signal coverage or interfering sources as well as to find appropriate approaches to solve these issues. The rightness of the performed simulations is verified by field measurements in cooperation with the Czech Telecommunications Office (CTU), and finally a discussion on how to improve the performance of SFN networks follows.
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Planning of Single Frequency Networks for DVB-T2
Barta, V. ; Polak, L. ; Cidl, P.
Nowadays, especially in Europe, the second generation of Digital Video Broadcasting Terrestrial system, abbreviated as DVB-T2, gradually replaces its predecessor DVB-T. Compared to DVB-T, DVB-T2 is a more versatile system with several configuration settings. Thanks to this, the planning of Single Frequency Networks (SFNs) used to effectively cover a certain area by DVB-T2 signal can be more flexible and straightforward. This paper deals with the design of SFNs for DVB-T2, especially with focus on the study of DVB-T2 system parameters (e.g. guard interval) and transmission conditions (e.g. multipath propagation) directly affecting performance of SFNs. For this purpose, RadioLab, RadioBase and Networks SFN utilities from CRC data software are used. Real DVB-T2 system configuration for Multiplex 21 (MUX 21) used in Brno (Czech Republic) is employed in this study. The simulation-based results can help to identify places with lower signal coverage or interfering sources as well as to find appropriate approaches to solve these issues.
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Performance analysis of SFNs transmitters of DVB-T2
Bárta, Vojtěch ; Miloš, Jiří (referee) ; Polák, Ladislav (advisor)
The diploma thesis deals with the design and analysis of Single Frequency Networks (SFNs) transmitters for Digital Video Broadcasting – second generation of the Terrestrial (DVB-T2). In this thesis, the software of the Czech company CRC data is used. Main attention is focused on the SFN Networks computational system for the analysis and design od DVB-T2 SFN networks, in which a series of simulations of the transmitting Multiplex 21 (CH26) have been performed. The simulation-based results are used to identify locations with lower signal coverage or interfering sources as well as to find appropriate approaches to solve these issues. The rightness of the performed simulations is verified by field measurements in cooperation with the Czech Telecommunications Office (CTU), and finally a discussion on how to improve the performance of SFN networks follows.
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Analysis of the transmission in the mobile digital audio broadcasting
Kresta, Daniel ; Ulovec,, Karel (referee) ; Kratochvíl, Tomáš (advisor)
This thesis deals with an analysis of a system called Digital Audio Broadcast and describes its mathematical model created in MATLAB program. In the first part basic blocks of a transmitter and a receiver are analyzed along with their principles. Then different types of transmission channels for static, portable and mobile receivers are described. The second part contains description of the DAB mathematical model itself. Individual blocks are described in the order of the DAB signal path, from the transmitter through the transmission channel to the receiver side. In this part the graphical user interface is also described. In the final part the results of experimental measurements and simulations are presented.
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Assignment of the OFDM signal cyclostationary detector behaviour.
Lehocký, Jiří ; Šimša, Jan (referee) ; Šebesta, Vladimír (advisor)
Master’s thesis belongs to the Cognitive radio network sphere. These networks utilize frequency spectrum more effectively than networks used in present radio communications. The Cognitive radio concept makes coexistence of classic and cognitive radio networks possible. Attention is aimed at spectrum sensing as the key task of the Cognitive radio. Main properties of the cyclostationary detector, as the detector, that reaches high probability of the detection at a very low signal to noise ratio with apriori knowledge of the transmitted signal's cyclic frequency, are examined in this paper. The OFDM signals, that inherit cyclostationarity from cyclic prefix, used in the real systems have been chosen for testing the properties of the detector. The influences of decimation and multipath propagation on the probability of detection are quantitatively expressed. The optimal values for the weights of the multicycle detector are determined.
|
|
|
Channel estimation in CDMA systems
Kadlec, Petr ; Prokopec, Jan (referee) ; Kejík, Petr (advisor)
The subject of this work deals with the problem of channel estimation for CDMA systems. This method of multiple access when individual users share the same full bandwidth simultaneously and are differentiated with any of pseudorandom sequences, is now the most perspective method. That is proved by its wide implementation in mobile networks of the third generation and higher systems. This work describes basic theory principles of spread spectrum, above all DS-CDMA (Direct Sequence-CDMA) and furthermore some phenomena of radio wireless channel that affect changes in transmitted signal in its way from transmitter to receiver. Terms of fading, multipath propagation, loss, refraction, scattering of the wave and Rice and Rayleigh probability density functions are mentioned. The third chapter deals with yet known and used capabilities of channel estimation. Differences, advantages and disadvantages of so-called blind estimation or training-based estimation are discussed. Two algorithms: LS method and sliding correlator are analyzed in more detail. There is also description of their simulations in Matlab and some results of these simulations are discussed. The last chapter deals with comparison of main characteristics and achievable accuracy of wireless channel impulse response estimation by both methods, and their possible utilization in real live.
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