Dissertation thesis deals with methods for finding the location of the device in the Internet, based on knowledge of the IP address. The process is called IP geolocation and is currently solved by geolocation databases or by measurement of network properties to the IP address. The disadvantage of nowadays geolocation databases is an incorrect information about some locations, because they can be in large distance from correct position. The aim of the thesis is to develop a method for verification of a position from geolocation database using delay measurement. Because of it, there is a detail analysis of influence of partial delays on the distance estimation accuracy, calculated using measured delay between the landmark and the target IP address. For the same reason, long-term delay measurement was performed, where the IP geolocation accuracy was compared using calibration data from previous measurements. On this background, Cable Length Based Geolocalisation (CLBG) method is proposed. Principle of this method is built on the properties of partial delays, which depend on the length of transport media. Firstly, the method measures round trip time (rtt), which is subsequently lowered by intermediate devices and end stations delay. The geographical distance is estimated using signal speed in the transport media. Further, the winding media parameter is established, which is used to determine a constraint around the landmark. The intersection of all constraints defines the area, where the target IP is. The IP geolocation using CLBG gives better results than simpler methods (ShortestPing, GeoPing and SOI), in comparison with more advanced methods (CBG and Octant) the accuracy is similar. The disadvantage of the CLBG method is the size of region, where the target lies, but this is due to its purpose. The position found in geolocation database can be checked by evaluation if it lies in the region.

Cognitive radios (CRs) are devices that are capable of sensing the spectrum and using its free portions in an opportunistic manner. The free spectrum portions are referred to as white spaces or spectrum holes. It is widely believed that CRs are one of the key enabling technologies for realizing a new regulatory spectrum management paradigm, viz. dynamic spectrum access (DSA). CRs often employ software-defined radio (SDR) platforms that are capable of executing artificial intelligence (AI) algorithms to reconfigure their transmission/reception (TX/RX) parameters to communicate efficiently while avoiding interference with licensed (a.k.a. primary or incumbent) users and unlicensed (a.k.a. secondary or cognitive) users. When different stakeholders share a common resource, such as the case in spectrum sharing, security, privacy, and enforcement become critical considerations that affect the welfare of all stakeholders. Recent advances in radio spectrum access technologies, such as CRs, have made spectrum sharing a viable option for significantly improving spectrum utilization efficiency. However, those technologies have also contributed to exacerbating the difficult problems of security, privacy and enforcement. In this dissertation, we review some of the critical security and privacy threats that impact spectrum sharing. We also discuss ex ante (preventive) approaches which mitigate the security and privacy threats and help spectrum enforcement. / Ph. D.