Internet of Drones: a Survey on Communications, Technologies, Protocols, Architectures and Services

The Internet of Drones (IoD) recently gained momentum due to its high adaptability to a wide variety of complex scenarios. Indeed, Unmanned Aerial Vehicles (UAVs) can successfully be employed in different application scenarios, like agriculture, search and rescue missions, surveillance systems, mission-critical services, etc., thanks to some technological and practical advantages: high mobility, capability to extend wireless coverage areas, or ability to reach places inaccessible to humans. Moreover, the employment of drones promisingly improves different network architectures performance indexes, i.e., reliability, connectivity, throughput, delay. Nevertheless, the adoption of networks of drones gives rise to several issues related to the unreliability of the wireless medium, batteries lifetime, high mobility degree and frequent topology changes. Moreover, security and privacy issues need to be properly investigated. This explains the very large number of works produced in the recent literature on IoD-related topics. With respect to other surveys on IoD-related topics, this work categorizes the multifaceted aspects of IoD, proposing a classification of the IoD environment. The proposed classification approach develops along two main directions. At a macroscopic level, it follows the structure of the Internet protocol stack, starting from the physical layer and extending to the upper layers, without neglecting crosslayer and optimization approaches. At a finer level, all the most relevant works belonging to each layer of the stack are further classified, according to the different issues peculiar of the layer, and highlighting the most relevant differences with the other surveys present in literature. Finally, a discussion on the main research challenges and possible future directions is carried out, focusing on the open issues and the most promising technologies in the IoD field.