# A Review of Flying Ad Hoc Networks: Key Characteristics, Applications, and Wireless Technologies
## 7 Integration of Technologies with the UAV-Networked Systems  
Recently, UAVs have begun to be integrated with several technologies, several of which technologies are discussed in this subsection, as shown in Figure 6.  
Figure 5: FANET Routing Protocols: position-based, topology-based, DTN, heterogeneous, cluster-based, and swarm-based. * _Augmented reality (AR) and Virtual Reality (VR) technologies (Figure 6, box A)_: VR, which is shown in Figure 6, box A, has been integrated with UAV-networked systems for greater integration of the virtual and real worlds. Such integration can create a virtual environments for multiple purposes, including marketing, agriculture, entertainment, education, and more, by taking over people's vision and making them feel as if they are somewhere else. AR is considered a variation of VR; VR technology, there is an essential need for 3D data on a large scale. In this regard, UAVs that can freely fly in the sky are excellent tools for collecting 3D data. Several studies have investigated the use of VR technology and UAV networks [5; 6; 7; 8; 9]. The main challenges of UAV-enabled VR include the low battery lifetime and computing capacity of VR users, which in turn cause issues with content caching and transmission. VR applications need a high data rate and low latency. In this regard, AI and ML techniques bring together novel NN ideas from echo state networks (ESNs) and the liquid state machine (LSM), which can enable user reliability prediction in order to find the optimal content level for transmission and caching [7; 101; 102]. * _IoT-enabled UAV communication system (Figure 6, box B)_: The integration of UAVs with IoT is called the Internet of Flying Things (IoT) [10; 11] or Internet of Drone Things (IoDT) [12]. IoT or IoDT represents a new research topic related to IoT, cellular networks, cloud, fog, and edge computing, big data, intelligent computer vision, and security techniques. IoFT or IoDT can efficiently support different applications in various fields ranging from disaster management to smart industry, providing high connectivity, scalability, flexibility, and availability. Although integrating UAVs with IoT improves the scalability, connectivity, stability, reliability, and security of real-time IoT applications, there are several open challenges, including interference and collision, UAV selection and placement, UAV control and management, security issues, the power limitations of IoT devices, path planning, and more [66; 103; 104; 105; 106; 107; 108]. Figure 6: The main technologies integrated with UAVs: augmented and virtual reality (AR and VR), IoT, cloud, edge, and fog computing, and cellular networks. * _Integration with Cloud Computing (Figure 6, box C):_ As shown in Figure 6, box C, cloud computing has been integrated with FANETs; known as cloud-based UAV or flying cloud computing, this can improve and increase storage, network bandwidth, and processing. Such an integrated system includes three main layers: a UAV layer, a cloud server layer, and a ground control system (GCS)/client layer. The UAV layer collects sensor data such as pressure, temperature, etc., while flying and transmits the collected data to the cloud for storage and processing using 3G/4G/5G cellular communication devices or other technologies such as WiMAX, WiFi, etc. The communication layer is responsible for providing wireless connectivity for the UAVs and GCS any time and anywhere without any limitations on communication range. The last layer contains the cloud servers that store and process different types of data, such as geographical location parameters, environment variables, sensor data, images, etc., received from the UAVs to detect various events [10; 11; 109; 110]. Although flying cloud computing provides many advantages in addition to the existing challenges in traditional FANETs, new issues arise as well. The major challenges that appear in cloud-based applications include large bottlenecks, latency due to centralized processing, lack of offline processing, and security issues.