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THE REDUCTION OF SIGNAL DYNAMIC IN ORTHOGONAL FREQUENCY DIVISION MULTIPLEX SYSTEMS
Urban, Josef ; Lúč, Andrej (referee) ; Galajda,, Pavol (referee) ; Maršálek, Roman (advisor)
This doctoral thesis is focused into the area of multicarrier radio communications systems. These systems are perspective for current and incoming mobile communications and wireless networks. Advantages of multicarrier systems like better multipath propagation resistivity are redeemed by some disadvantages. The high peak to average power ratio of transmitted signal belongs to these disadvantages, for its inconvenience for high efficient power amplification. The thesis concerns with peak to average power ratio reduction methods for OFDM systems, that belongs to the most used multicarrier systems. One of the main objectives is the modification of the existing methods with the intention of complexity reduction. Following subject of interest is the analysis of suitable methods combinations possibilities for more significant peak to average power ratio reduction. One part of this thesis is research of influence of these methods on the OFDM signals with different parameters.
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Methods of interleaving data
Soudek, Michal ; Němec, Karel (referee) ; Křivánek, Vítězslav (advisor)
The initial part of my work is dedicated to overall introduction into the transmission systems and its categories. Further the work is focused on dividing of security codes which are used for transmission systems. In the next chapter is analyzed the problems of error origin, mathematical transcription of errors, categorizing of errors which can generate during transmission. The following chapter deals with description of convolutional codes describing security against errors, principle of serial consecution interpretation on parallastic consecution and visa versa. Here is outlined problems of convolutional codes input. In the next part are mentioned three convolution codes which are used for security against burst errors. In the next chapter is mentioned problems of message interleaving and description of used methods, how they originate and detailed description, how the errors are eliminated with the help of long segment interleaving. In the next chapter are described techniques which are used for clustered errors suppression. The last chapter is dedicated to the practical part of my thesis. There are detail descriptions and simulation techniques how the security of non-secure section is developed, transmission on line, burst errors induction on transmitted secure data and consecutive amendment or clustered errors division in transceiver. For the simulation there were utilized three convolutional codes for clustered errors amendment and two interleaving techniques.
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PAPR reduction in OFDM and simulation in Scilab
Maňák, David ; Maršálek, Roman (referee) ; Urban, Josef (advisor)
Main goal of this dissertation is read over principal and properties of the OFDM modulation. Onward we become acquainted with basic methods for PAPR dynamics reduction in OFDM such as Clipping or Interleaving. Simulation of reduction methods will be realized in Scilab environment, in which are made basic functions for OFDM modulator and demodulator. Furthermore there are created functions for PAPR reduction methods. All established functions are implemented in the GUI.
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NEW CHANNEL CODING METHODS FOR SATELLITE COMMUNICATION
Rumánek, Jaroslav ; Levický, Dušan (referee) ; Žalud, Václav (referee) ; Šebesta, Jiří (advisor)
This dissertation thesis deals with new progressive channel coding methods for data transmission using satellite transponder. The design of the system for SMS transmission, in which novel turbo coding methods are applied, is discussed too. An achievement of the lowest output power and the smallest user aperture is the principal aim of the new method applications. Design of system that would be able to the error free SMS transmission by very low signal to noise ratio is analyzed in this dissertation thesis. The work is focused on energy budget, modification and implementation of new turbo code types and using unique properties, development of new bit error rate estimation methods and methods for determination of final SMS form. The main contribution is the new type of turbo code development that have optimal properties for this usage, development of new bit error rate estimation method and development of method that is able to determine final form of SMS on the basis SMS frame structure and turbo decoding theory when the bit error rate is not zero.
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Antierror systems with interleaving
Pacher, Jakub ; Zeman, Václav (referee) ; Němec, Karel (advisor)
This work involves in anti-error coding systems with interleaving. At first is given summary of high-frequency use error correction codes. Below there are described two basic techniques of interleaving and their confrontation. The next text is focusing on survey and characteristics of codes which conform to submission. After selection of optimal system is verified its function in MATLAB environment. Final step is creation of functional application in C++ environment. This application serves to transmission of error correction BMP pictures.
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Simulation of ADSL error protection systems
Bernat, Zbyněk ; Krajsa, Ondřej (referee) ; Šilhavý, Pavel (advisor)
The main objective of this thesis was to create a model of forward error correction (FEC) system used in ADSL modem, which will be able to check its individual settings using the test methods specified in Recommendation G.996.1. The work is divided into two basic parts – theoretical and practical. The first part describes the basic functional characteristics of ADSL system, with attention being paid to aspects affecting the activity and setting of the error protection system. There are also discussed the theoretical basics of FEC coding techniques used in ADSL. The work also contains a description of the method for testing DSL system resistance against impulsive interference, which is specified in Recommendation G.996.1. The practical part of this thesis contains a description of the proposed model of the FEC system. The model was implemented in the programming environment Matlab Simulink. The proposed model includes the simulation of FEC coding process, DMT modulation and transmission channel with the impulse interference and the background noise. The proposed program is able to calculate parameters for setting FEC system from the specified data transfer rates and the requirement for interleaving. In addition, allows you to set the parameters of transmission line and sources of impulse interference and of the background noise. Under the set of input characteristics of the transmission is calculated bit allocation and the resulting parameters are given to a computational core of the model. In the application can be performed two types of test tasks. The first one is based on the Recommendation G.996.1 and makes it possible to determine probability of errored second. The second test task is for the measurement of resistance of the transmission system against impulsive interference. The results of the simulations are summarized in the conclusion of work.
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THE REDUCTION OF SIGNAL DYNAMIC IN ORTHOGONAL FREQUENCY DIVISION MULTIPLEX SYSTEMS
Urban, Josef ; Lúč, Andrej (referee) ; Galajda,, Pavol (referee) ; Maršálek, Roman (advisor)
This doctoral thesis is focused into the area of multicarrier radio communications systems. These systems are perspective for current and incoming mobile communications and wireless networks. Advantages of multicarrier systems like better multipath propagation resistivity are redeemed by some disadvantages. The high peak to average power ratio of transmitted signal belongs to these disadvantages, for its inconvenience for high efficient power amplification. The thesis concerns with peak to average power ratio reduction methods for OFDM systems, that belongs to the most used multicarrier systems. One of the main objectives is the modification of the existing methods with the intention of complexity reduction. Following subject of interest is the analysis of suitable methods combinations possibilities for more significant peak to average power ratio reduction. One part of this thesis is research of influence of these methods on the OFDM signals with different parameters.
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NEW CHANNEL CODING METHODS FOR SATELLITE COMMUNICATION
Rumánek, Jaroslav ; Levický, Dušan (referee) ; Žalud, Václav (referee) ; Šebesta, Jiří (advisor)
This dissertation thesis deals with new progressive channel coding methods for data transmission using satellite transponder. The design of the system for SMS transmission, in which novel turbo coding methods are applied, is discussed too. An achievement of the lowest output power and the smallest user aperture is the principal aim of the new method applications. Design of system that would be able to the error free SMS transmission by very low signal to noise ratio is analyzed in this dissertation thesis. The work is focused on energy budget, modification and implementation of new turbo code types and using unique properties, development of new bit error rate estimation methods and methods for determination of final SMS form. The main contribution is the new type of turbo code development that have optimal properties for this usage, development of new bit error rate estimation method and development of method that is able to determine final form of SMS on the basis SMS frame structure and turbo decoding theory when the bit error rate is not zero.
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Antierror systems with interleaving
Pacher, Jakub ; Zeman, Václav (referee) ; Němec, Karel (advisor)
This work involves in anti-error coding systems with interleaving. At first is given summary of high-frequency use error correction codes. Below there are described two basic techniques of interleaving and their confrontation. The next text is focusing on survey and characteristics of codes which conform to submission. After selection of optimal system is verified its function in MATLAB environment. Final step is creation of functional application in C++ environment. This application serves to transmission of error correction BMP pictures.
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Simulation of ADSL error protection systems
Bernat, Zbyněk ; Krajsa, Ondřej (referee) ; Šilhavý, Pavel (advisor)
The main objective of this thesis was to create a model of forward error correction (FEC) system used in ADSL modem, which will be able to check its individual settings using the test methods specified in Recommendation G.996.1. The work is divided into two basic parts – theoretical and practical. The first part describes the basic functional characteristics of ADSL system, with attention being paid to aspects affecting the activity and setting of the error protection system. There are also discussed the theoretical basics of FEC coding techniques used in ADSL. The work also contains a description of the method for testing DSL system resistance against impulsive interference, which is specified in Recommendation G.996.1. The practical part of this thesis contains a description of the proposed model of the FEC system. The model was implemented in the programming environment Matlab Simulink. The proposed model includes the simulation of FEC coding process, DMT modulation and transmission channel with the impulse interference and the background noise. The proposed program is able to calculate parameters for setting FEC system from the specified data transfer rates and the requirement for interleaving. In addition, allows you to set the parameters of transmission line and sources of impulse interference and of the background noise. Under the set of input characteristics of the transmission is calculated bit allocation and the resulting parameters are given to a computational core of the model. In the application can be performed two types of test tasks. The first one is based on the Recommendation G.996.1 and makes it possible to determine probability of errored second. The second test task is for the measurement of resistance of the transmission system against impulsive interference. The results of the simulations are summarized in the conclusion of work.
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