A friendly physical layer warden system

Abstract

Wireless communication technologies have become the focus of attention in recent years. Studies in this field are of great importance as they offer a direct solution to the problems of daily life. Mobile communication, satellite communication, terrestrial communication and maritime communication are the pioneers in the wireless communication sector. Wireless communication has become widespread and popular because it is frequently used in daily life. For example, in today's world, almost everyone has basic knowledge about technologies such as Bluetooth, Wi-Fi, 3G, 4G, 5G. It can be seen that even people who are not technically involved follow the developments of these technologies today. The wireless method of transmitting information brings great comfort to human life. However, with the convenience of wireless communication, some potential dangers may also occur. Wireless transmission takes place by converting the information into a signal and broadcasting it to the open environment with the help of antennas and receiving this broadcast by the desired people. Due to the nature of wireless communication, this broadcast to the open environment may pose a danger because the wireless medium is accessible to all users in the environment. Some of these dangers are interfering with the communication between the communicating devices for malicious purposes or revealing confidential information by decoding a communication signal by someone else. These potentially dangerous interventions are called wireless attacks. Communication architecture is generally designed as a multi-layered structure. The most common structure is the OSI (Open Systems Interconnection) model. This model; It consists of physical layer, data link layer, network layer, transport layer, session layer, presentation layer and application layer. New wireless transmission techniques are discussed and designed every day in the literature. Thanks to the new methods designed, wireless communication is becoming more secure day by day. Encryption methods developed by the science of cryptography are used to provide information security. These encryption methods are frequently used in the layers other than the physical layer. However, contrary to expectations, the physical layer has not received enough attention in studies against wireless threats. Within the scope of the literature review, studies on the detection of wireless threat elements were investigated. Physical layer approaches have been examined and it has been seen that these studies are generally aimed at receiver systems. A different perspective has been brought in this thesis to detect wireless attackers. In this thesis, a friendly physical layer guard system is proposed. This warden system has the ability to detect if the transmission between two users is under any attack. Additionally, if an attack is taking place, the system can also detect the type of attack. The proposed warden system has a multi-antenna architecture, so it can also determine which direction the attacker is in. In the first stage of the study, it was mentioned why the communication environment should be secure.