Physical layer solutions for the security of wireless communications

The rapid growth in the number of wireless devices has significantly increased the complexity and vulnerability of communication networks. In wireless communication, the inherent shared nature of the wireless medium creates unique challenges for security, including eavesdropping, jamming, and unauthorized access. Traditional cryptographic methods, though highly effective, are often unsuitable for many wireless devices due to their limited computational power and energy constraints. This has spurred the need for alternative solutions that can complement standard cryptography algorithms. In particular, some characteristics of the physical layer can be leveraged to enhance security without overburdening devices. Physical Layer Security offers a promising approach by taking advantage of some inherent properties of the wireless channel, such as fading, noise, and interference, to secure communications. This thesis focuses on two major aspects of physical layer security. First, an analysis of wireless channels for secure key generation is presented, focusing on the spatial correlation properties of the channel and its impact on key generation. Then, the use of Frequency Diverse Arrays for geofencing applications is proposed, showing the capabilities of Frequency Diverse Arrays, and an analysis on their actual advantages.