Physical layer security in wireless HetNets avionics and satellite communication systems

Today’s aeronautical communications increasingly rely on wireless communication to exchange information within an aircraft, between aircrafts, between aircraft and the ground network, and between aircraft and the satellite. The future avionics communications industry foresees an amalgamation of different radio access technologies to provide sufficient bandwidth for the growing demand for avionics applications onboard the aircraft as well as on the ground. This amalgamation of different types of radio access technologies, on one hand, brings much-needed resources, but, on the other hand, it also leads to the growing numbers of cybersecurity attacks which point at different domains and attract a variety of cybersecurity attackers. Aeronautical networks consist of several interconnected devices that enable data management and ensure that the messages using the aircraft applications are exchanged within a given timeframe. This constraint makes the design of the communication system highly challenging because of the requirement of a guaranteed bandwidth and a pre-defined quality of service. These issues raise several security concerns as to the security of both personal and sensitive data. Almost within all wireless communication systems, the initial countermeasures for vulnerabilities such as authentication, integrity and confidentiality are employed in the top layers within the protocol stack using different encryption schemes that are based on mathematical operations and the security provided by the techniques is usually referred to as the computational security. Even though these techniques have shown to be very effective over the years but the research has shown that when the aim is to design a secure communication system, then the attributes of the physical layer such as its imperfections must also be considered, which can then result in additional security, e.g., in physical layer, white noise is considered an imperfection but this noise can be used to hide secure messages. If these techniques are employed in addition to the traditional security measures without the loss of data rate, then they can complement the traditional security techniques. This chapter aims to highlight some of the secrecy mechanisms and provide some insight into the physical layer techniques that can be employed for a secure and reliable transmission. The chapter will also highlight the performance metrics that are employed to evaluate the channel secrecy capacity and secrecy outage probability. Finally, to sum up, an example of a physical layer attack is presented, and it is shown how the PHY-layer security technique can be employed as a countermeasure.