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Spectrum sensing in the cognitive radio networks - influence of real communication link parameters
Lekomtcev, Demian ; Marchevský,, Stanislav (referee) ; Richterová,, Marie (referee) ; Maršálek, Roman (advisor)
The doctoral thesis deals with spectrum sensing in cognitive radio networks (CRN). A number of international organizations are currently actively engaged in standardization of CRN and it points out to the fact that this technology will be widely used in the near future. One of the key features of this technology is a dynamic access to the spectrum, which can be affected by many different harmful factors occurring in the communication chain. The thesis investigates the influence of selected factors on the spectrum sensing process. Another contribution of the work is the optimization of the Kolmogorov - Smirnov statistical test that can be applied for the primary user signal detection. The work also incorporates the analysis of the influence of the harmful effects caused by the commonly used transmitters and receivers on various spectrum sensing methods. The investigations are verified by the results of the simulations and also by the measurements with experimental platforms based on the software-defined radio (SDR).
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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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Spectrum sensing and multicarrier systems optimization for cognitive radio
Povalač, Karel ; Šimša, Jan (referee) ; Galajda,, Pavol (referee) ; Maršálek, Roman (advisor)
The doctoral thesis deals with spectrum sensing and subsequent use of the frequency spectrum by multicarrier communication system, which parameters are set on the basis of the optimization technique. Adaptation settings can be made with respect to several requirements as well as state and occupancy of individual communication channels. The system, which is characterized above is often referred as cognitive radio. Equipments operating on cognitive radio principles will be widely used in the near future, because of frequency spectrum limitation. One of the main contributions of the work is the novel usage of the Kolmogorov – Smirnov statistical test as an alternative detection of primary user signal presence. The new fitness function for Particle Swarm Optimization (PSO) has been introduced and the Error Vector Magnitude (EVM) parameter has been used in the adaptive greedy algorithm and PSO optimization. The dissertation thesis also incorporates information about the reliability of the frequency spectrum sensing in the modified greedy algorithm. The proposed methods are verified by the simulations and the frequency domain energy detection is implemented on the development board with FPGA.
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Classification of digital modulation type
Balada, Radek ; Kováč,, Michal (referee) ; Povalač, Karel (advisor)
The aim of master’s thesis is a classification of digital modulation type. The interest in modulation classification has been growing for last years. It has several possible roles in both civilian and military applications such as spectrum sensing, signal confirmation, interference identification, monitoring and so on. Modulation classification is an intermediate step between signal detection and successful demodulation. Therefore the known methods are based on different statistics obtained from received signals. These statistics can be derived from continuous time signals and they hold for sampled signals.
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Matched filter
Lehocký, Jiří ; Maršálek, Roman (referee) ; Šebesta, Vladimír (advisor)
This work implies the essential possibilities of spectrum sensing and their use. Main attention is paid to matched filtering as a method achieving high processing gain in a short time. The impact of main parameters on the result of the detection is shown in this work. By analysing the output of detector not only in ideal conditions, but also in real transmission system, the most realibly detectable sequences were identified. Further the possibilities of spectrum sensing by matched filter in OFDM based systems are presented.
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Spectrum sensing in the cognitive radio networks - influence of real communication link parameters
Lekomtcev, Demian ; Marchevský,, Stanislav (referee) ; Richterová,, Marie (referee) ; Maršálek, Roman (advisor)
The doctoral thesis deals with spectrum sensing in cognitive radio networks (CRN). A number of international organizations are currently actively engaged in standardization of CRN and it points out to the fact that this technology will be widely used in the near future. One of the key features of this technology is a dynamic access to the spectrum, which can be affected by many different harmful factors occurring in the communication chain. The thesis investigates the influence of selected factors on the spectrum sensing process. Another contribution of the work is the optimization of the Kolmogorov - Smirnov statistical test that can be applied for the primary user signal detection. The work also incorporates the analysis of the influence of the harmful effects caused by the commonly used transmitters and receivers on various spectrum sensing methods. The investigations are verified by the results of the simulations and also by the measurements with experimental platforms based on the software-defined radio (SDR).
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Spectrum sensing and multicarrier systems optimization for cognitive radio
Povalač, Karel ; Šimša, Jan (referee) ; Galajda,, Pavol (referee) ; Maršálek, Roman (advisor)
The doctoral thesis deals with spectrum sensing and subsequent use of the frequency spectrum by multicarrier communication system, which parameters are set on the basis of the optimization technique. Adaptation settings can be made with respect to several requirements as well as state and occupancy of individual communication channels. The system, which is characterized above is often referred as cognitive radio. Equipments operating on cognitive radio principles will be widely used in the near future, because of frequency spectrum limitation. One of the main contributions of the work is the novel usage of the Kolmogorov – Smirnov statistical test as an alternative detection of primary user signal presence. The new fitness function for Particle Swarm Optimization (PSO) has been introduced and the Error Vector Magnitude (EVM) parameter has been used in the adaptive greedy algorithm and PSO optimization. The dissertation thesis also incorporates information about the reliability of the frequency spectrum sensing in the modified greedy algorithm. The proposed methods are verified by the simulations and the frequency domain energy detection is implemented on the development board with FPGA.
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Matched filter
Lehocký, Jiří ; Maršálek, Roman (referee) ; Šebesta, Vladimír (advisor)
This work implies the essential possibilities of spectrum sensing and their use. Main attention is paid to matched filtering as a method achieving high processing gain in a short time. The impact of main parameters on the result of the detection is shown in this work. By analysing the output of detector not only in ideal conditions, but also in real transmission system, the most realibly detectable sequences were identified. Further the possibilities of spectrum sensing by matched filter in OFDM based systems are presented.
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