# Machine-Learning-Enabled Intrusion Detection System for Cellular Connected UAV Networks
## 1 Introduction  
Recently, Unmanned Aerial Vehicles (UAVs) or drones have become popular and have been used for a variety of purposes in terms of everyday flying objects connected to the internet and able to identify themselves to other devices by sharing information via smart devices such as mobile phones and tablets. UAVs are flying objects that can fly independently or with the assistance of human pilots. UAVs are used for package delivery, aerial mapping, irrigation, environmental management, aerial photography, monitoring, rescue operations, and other critical applications. The reliability of UAV and its wireless communications is important for those critical applications. Security schemes and intrusion detection techniques are used to ensure critical security features. For communication, UAVs can communicate with terrestrial networks such as ground Base Stations (BSs) and non-terrestrial networks such as low-altitude satellites. Space-based technologies, which include a newly named network of communications satellites for non-terrestrial uses, permit global telecommunications systems to transmittheir signals based on voice, video, and other data from multiple access points [1]. Terrestrial infrastructure requirements can be reduced by using communications satellites so that more cost-effective service delivery options can be provided. Other applications of remote sensing satellites are in the agricultural area (for monitoring soil, drought, and crop development), environment (surveying water cycles, air quality, forests and state of ecosystems), UAV (communication), global health objectives (monitoring disease patterns, predict risk areas and define regions), and Internet of Things (IoT), where things are connected to the internet, which can be implemented in factory automation, smart homes, etc. [2]. According to [3], it is expected that there will be more than 27 billion devices connected to the internet by 2026 [4]. 5G networks will be able to support massive IoT (mIoT) devices, which will change the way society can interact with basic everyday objects. The majority of mobile networks are terrestrial, so they cannot cover remote areas, e.g., deserts, oceans, and forests, as they lack terrestrial infrastructure and universality of telecommunication software [5]. Similarly, UAVs flying at low altitudes cannot operate beyond cellular coverage area. Thus, satellite infrastructures, which extend and complement the terrestrial network, play a vital and crucial role in UAV networks [6]. The term Internet of Remote Things (IoRT) has been studied in [7], which reviews satellite-based IoTs in terms of Media Access Control (MAC) protocols for the sensor of satellite networks, supporting IPv6, heterogeneous networks interoperability, and managing Quality of Service (QoS) criterion. It can also be used in drones to remotely control them. A constellation of Low Earth Orbit (LEO) satellite architecture, efficient spectrum allocation, heterogeneous networks agreement, access, and routing protocols has been presented in [8]. Another novel architecture is designed to obtain intelligent, rapid, and efficient Heterogeneous Space and Terrestrial Integrated Networks (H-STINs) [9], which includes a proposed intelligent data center based on Software-Defined Networking (SDN)/Network Functions Virtualization (NFV) technology. The fifth generation (5G) networks can be deployed in satellite-based communication to achieve high bandwidth, low latency, and increasing coverage [10; 11; 12]. The introduction of UAVs into telecommunications networks, either as aerial users or as communication platforms, introduces new design possibilities as well as hurdles. Because of the high elevation and mobility of UAVs, service quality requirements, and the high chance of UAVs to ground Line of Sight (LoS) networks, both cellular-connected UAV communication and UAV-assisted wireless communication differ significantly from their terrestrial counterparts. In this paper, we focus on UAVs as a cellular user.