Continuous-wave frequency-modulated radar, or FMCW radar, is simple in design, small in size and weight and uses low transmitting power. The range resolution depends on the bandwidth. FMCWradar is used in applications ranging from guided weapons systems to vehicle collision avoidance systems. Measuring the distance to the target is the essential feature of FMCW radar. Firstly, this thesis introduces the basic structure of the FMCW radar and the principle formeasuring distance. Secondly, by using software-dened radio (SDR),FMCW radar can be implemented and congured with a reduced costand complexity. In this report, the radar is implemented by means ofthe software GNU Radio Companion with a test signal. HackRF may be used in future work with an osmocom source instead of the testsignal.

Stepping stones are compromised hosts in a network which can be used by hackers and other malicious attackers to hide the origin of connections. Attackers hop from one compromised host to another to form a chain of stepping stones before launching attack on the actual victim host. Various timing and content based detection techniques have been proposed in the literature to trace back through a chain of stepping stones in order to identify the attacker. This has naturally led to evasive strategies such as shaping the trac di erently at each hop. The evasive techniques can also be detected. Our study aims to adapt some of the existing stepping stone detection and antievasion techniques to software-dened networks which use network function virtualization. We have implemented the stepping-stone detection techniques in a simulated environment and use sFlow for the trac monitoring at the switches. We evaluate the detection algorithms on di erent network topologies and analyze the results to gain insight on the e ectiveness of the detection mechanisms. The selected detection techniques work well on relatively high packet sampling rates. However, new solutions will be needed for large SDN networks where the packet sampling rate needs to be lower.

Cognitive radio technology has been an important area of research in telecommunications for solving the problem of spectrum scarcity. That\'s because in addition to allowing dynamic allocation of the electromagnetic spectrum, cognitive radios must be able to identify the non cognitive user\'s transmission on the channel. This operation is only possible through the continuous sensing of the electromagnetic spectrum. In this context, this paper presents a detailed study on spectrum sensing, an important stage in cognitive radio technology. For the presentation of this work, a detailed study on software dened radio (SDR) was carried out, without which it would be impossible to work with cognitive radios, once they are implemented by means of SDR technology. It was also presented the tools GNU Radio and USRP, which together form a solution of SDR, through implementation of AM receivers. The theoretical foundations of spectrum sensing and blind source separation (BSS) are presented and then is made a detailed study of the use of BSS for spectral sensing. From the study of BSS, it is possible to use new metrics for decision making about the presence or the absence of a primary user in the channel. Throughout the study, simulations and implementations were conducted on MATLAB in order to perform various situations, and, nally, it is presented outcomes and conclusions reached during the work. / A tecnologia de rádio cognitivo tem sido uma importante área de pesquisa em telecomunicações para a solução do problema da escassez espectral. Isto porque, além de permitirem a alocação dinâmica do espectro eletromagnético, os rádios cognitivos devem ser capazes de identificar as transmissões de usuários não cognitivos no canal. Esta operação só é possível por meio do sensoriamento contínuo do espectro eletromagnético. Neste contexto, este trabalho apresenta um estudo detalhado sobre o sensoriamento de espectro, uma importante etapa da tecnologia de rádios cognitivos. Para a apresentação deste trabalho foi realizado um estudo detalhado a respeito de rádio definido por software (SDR), sem o qual não seria possível o trabalho com rádios cognitivos, uma vez que este é implementado por meio da tecnologia de SDR. Também foram apresentadas as ferramentas GNU Radio e USRP, que, juntas, formam uma solução de SDR, por meio de implementações de receptores AM. Os fundamentos teóricos de sensoriamento de espectro e separação cega de fontes (BSS) são apresentados e, em seguida, é realizado um estudo aprofundado do uso de BSS para o sensoriamento espectral. A partir do estudo de BSS, é possível utilizar novas métricas de decisão a respeito da presença ou não de um usuário primário no canal. Durante todo este trabalho foram realizadas implementações e simulações no MATLAB com a finalidade de executar diversas situações e, finalmente, são apresentados resultados verificados e conclusões obtidas neste trabalho. / Mestre em Ciências