A Survey of Physical Layer-Aided UAV Security

Low-cost Unmanned Aerial Vehicles (UAVs) and their swarms are increasingly being used and have become an integral part of various industries and aspects of daily life. They are being used in industries such as agriculture, delivery services, construction and to achieve critical tasks such as disaster relief, search and rescue operations, etc. As Unmanned Aerial Vehicles (UAVs) become increasingly pervasive and essential, they are becoming both a target for attack and the very weapon on which such attacks are carried out. For example, UAVs can be hacked and used to perform cyber attacks on targets such as power grids, and communication and military networks. To protect UAVs against cyber-attacks, different techniques both traditional (cryptography-based) and non-traditional (sound-based, video-based, physical layer (PHY) based) have been proposed in the literature. Traditional crypto-based authentication solutions usually involve high computational overhead and require the challenging task of managing secret keys. Recently introduced PHY-based solutions that exploit the inherent randomness of the wireless channels and non-ideal hardware characteristics have witnessed an increased interest from the research community resulting in many publications. Nevertheless, we noticed a lack of an up-to-date survey that keeps track of all the recent research developments in this new area of security research. Thus, the goal of this paper is to bridge the gap in the literature by providing a timely and comprehensive discussion on different techniques and methods proposed in the literature, summarizing their working principles, and highlighting the various strengths and weaknesses. We also discuss different challenges that physical layer security faces and potential future opportunities.