**Preface to "Unmanned Aerial Vehicles: Platforms, Applications, Security and Services"**

In the years to come, UAVs are expected to keep gaining momentum and be adopted for an ever-growing number of tasks in different fields. This creates multiple challenges in terms of system/navigation, requiring significant integration efforts, multiple testbeds and deployment results, and novel protocols. In the enabling of such systems, communications play a vital role, and so, issues like software-defined radio/networks, virtualized networks, heterogeneous networks and channel modeling will be key to make these systems possible, especially if we keep in mind the trend towards more network demanding applications, like video streaming for real-time monitoring. Moreover, issues like UAV identification, authentication and network security always remain critical factors, especially when the UAVs are deployed to provide aerial surveillance or civil security, among other things.

In this book, we present a collection of contributions from different authors that represent an advancement in different areas related to UAVs. In particular, the first chapter, entitled "Design and Analysis of Refined Inspection of Field Conditions of Oilfield Pumping Wells Based on Rotorcraft UAV Technology", deals with an oil well monitoring method. The authors propose the use of computer vision in the detection of working conditions in oil extraction, by making use of UAV aerial photography images combined with the YOLOv3 framework for tracking detection. Through different experiments, they prove the benefits of their proposal. The second chapter, entitled "Accurate Landing of Unmanned Aerial Vehicles Using Ground Pattern Recognition", presents a solution for high precision landing. The authors propose a vision-based landing solution that relies on ArUco markers that allow the UAV to detect the exact landing position from a high altitude (30 m). They evaluate their system through a platform based on Arduino hardware, and they show how their proposal improves the landing accuracy (offset of about 11 cm) compared to the traditional GPS-based one, whose offset is about 1–3 meters. The third chapter, entitled "An Efficient and Provably Secure Certificateless Blind Signature Scheme for Flying Ad-Hoc Network Based on Multi-Access Edge Computing", proposes an efficient and provably secure certificateless blind signature scheme (CL-BS), based on multi-access edge computing (MEC) for a FANET environment, using the concept of hyperelliptic curve. The scope of the paper involves the resolution of computational and communication issues of the existing security approaches. The authors propose the use of multi-access edge computing (MEC) in a UAV environment, with the help of the 5G mobile network enabling a secure communication between UAVs and the base station (BS). The fourth chapter, entitled "A Traceable and Privacy-Preserving Authentication for UAV Communication Control System", proposes a traceable and privacy-preserving authentication to integrate the elliptic curve cryptography (ECC), digital signature, hash function, and other cryptography mechanisms for UAV application. The authors designed a traceable and privacy protection protocol to conduct the UAVs' application in a sensitive control area. This study also analyzed the computation and communication costs, to prove that the proposed scheme is practical in the real world. The fifth chapter, entitled "A New FANET Simulator for Managing Drone Networks and Providing Dynamic Connectivity", deals with the possibility of providing wireless connectivity, using a flying ad hoc network (FANET) in all those emergency situations where the traditional network can encounter several difficulties. A software simulator is proposed to implement different models: footprint, human mobility and drone behavior. The sixth chapter, entitled "Onboard Visual Horizon Detection for Unmanned Aerial Systems with Programmable Logic", introduces a fast horizon detection algorithm suited for visual applications, to be used on board a small unmanned aircraft. For this purpose, the designed algorithm has a low complexity, in order to meet the power consumption requirements and to keep the computational cost low. The authors present formulae for distorted horizon lines. The performance of the proposed algorithm is tested on a real flight with the help of a FPGA implementation. Finally, the seventh chapter, entitled "LoRaWAN Networking in Mobile Scenarios Using a WiFi Mesh of UAV Gateways", proposes a double-layer network system called LoRaUAV. The system is based on an ad hoc WiFi network of unmanned aerial vehicle (UAV) gateways able to act as relay for the traffic generated between mobile LoRaWAN nodes and a remote base station (BS). The core of the system is a completely distributed mobility algorithm, based on virtual spring forces, that periodically updates the UAV topology to adapt to the movement of ground nodes. The proposed system is implemented in NS-3, and the performance, evaluated in a wild area firefighting scenario, shows the improvement in terms of the packet reception ratio (PRR).

> **Carlos Tavares Calafate, Mauro Tropea** *Editors*
