With the advancement in drone technology ; in just a few years ;drones will be assisting humans in every domain :But there are many challenges to be tackled ;communication being the chief one :This paper aims at providing insights into the latest UAV (Unmanned Aerial Vehicle ) communication technolo- gies through investigation of suitable task modules ; antennas ;resource handling platforms ;and network architectures :Additionally ;we explore techniques such as machine learning and path planning to enhance exist- ing drone communication methods :Encryption and opti- mization techniques for ensuring long lasting and se- cure communications ;as well as for power management ; are discussed :Moreover ;applications of UAV networks for di erent contextual uses ranging from navigation to surveillance ;URLLC (Ultra-reliable and low latency communications) ;edge computing and work related to arti cial intelligence are examined :In particular ; the intricate interplay between UAV ;advanced cellu- lar communication ;and internet of things constitutes one of the focal points of this paper :The survey en- compasses lessons learned ;insights ;challenges ;open issues ;and future directions in UAV communications : Dushantha Nalin K. Jayakody E-mail: dushanthaj@sltc.ac.lk Hwang-Cheng Wang E-mail: hcwang@niu.edu.tw 1Dept. of Electronics and Communication Engineering, The LNM Institute of Information and Technology, Jaipur, India. 2Centre for Telecommunication Research, School of Engineer- ing, Sri Lanka Technological Campus, Sri Lanka. 3School of Computer Science and Robotics, National Research Tomsk Polytechnic University Russia. 4Department of Electronic Engineering, National Ilan Univer- sity, Yilan, Taiwan. 5Department of Electronic and Communications Engineering, National Institute of Technology, Trichy, India.Our literature review reveals the need for more re- search work on drone todrone and drone todevice communications : Keywords 5G mobile communication Mobile communication Unmanned aerial vehicles Wireless networks Communication systems 1 Introduction UAVs (Unmanned Aerial Vehicles) or drones as they are popularly known are paving their ways into di erent elds of applications ;which has led to their increased presence in the consumer market. Signi cant research work is now being focused on communication problems associated with UAVs and how to remediate their vul- nerabilities. Drones help us in reaching areas dicult to access often because of the lack of physical infrastruc- ture. As a consequence, drones are often used for critical operations such as rescue ;surveillance ;transportation in various types of elds, including agriculture ;forestry ; environmental protection ;and security. Initially, drone units were used independently; nowa- days, however, multiple synchronized drones often per- form critical operations together. In these scenarios, drone communication plays a critical role. Thus, it is important to understand various aspects of UAV commu- nication. On the other hand, di erent types of wireless channels and network protocols are employed in drone communications. Therefore ;the communication mech- anism which is used for the UAV network depends on the application. For example, in outdoor communica- tion, it has been observed that a simple line of sight point-to-point communication link between the drone and the device can be utilized without any break in 2 Abhishek Sharma1et al. Fig. 1 Scope of communication technology with drones. signal transmission. Another example is surveillance, where drones e ectively communicate through satellite communication links. Satellite communication technique is a preferable choice for drone communication when they are used for security, defense, or more extensive outreach operations. On the other hand, for civil and personal applications, cellular communication technolo- gies are preferred. However, for indoor communication, especially in the case of the mesh network and Wire- less Sensor Network (WSN), communication through Bluetooth and other point-to-point (P2P) protocols has been more ecient. Communication to a multi-layered network can be a complicated process when applied to drones. Some of the signi cant concerns are illustrated below. Previous work [1] have explored various communi- cation and mission control approaches, for multi-drone applications, along with their classifying systems: cen- tralized and decentralized. In time-sensitive missions, centralized systems serve a better purpose. But ideally, a hybrid of both would give the best results, where drones are centrally operated and learn from each other. WiFi, Bluetooth, ZigBee, acoustic, and cellular technolo- gies were analyzed for a UAV communication system. It was concluded that the selection of communication technology should be made by taking into account pa- rameters like bandwidth, range, power requirements, speed, compatibility, payload weight, and cost. Yan- maz et al. [2] analyzed various types of technologies for a drone network with di erent functionalities suchas sensing, coordination, communication, and network- ing. Many useful suggestions were also provided, e.g., drones should be integrated into emerging large-scale networks such as future cellular networks. Asadpour et al.[3] showed that current wireless networking standards could not cope with the high mobility of UAVs and in- creased signal frequencies. Doppler e ect or changes in relative speeds and antenna directions associated with UAVs could lead to high packet losses. Selection of appropriate communication technology is essential and various aspects like accuracy, sum rate, antenna device, and resource handling platforms should be taken into consideration as suggested by researchers [4 {16]. Data transmission is a crucial aspect of any network, and appropriate routing protocol should be used accord- ingly. For a single UAV or a swarm of UAVs, networking is an important feature [17 {31]. Drones have been in- corporated into the wireless sensor network, vehicular communication system, and mobile communication net- work to extend their applications along with the use of internet of things. [32{42]. Arti cial intelligence ;navigation strategies, and cryp- tography have been integrated into UAV communica- tion techniques by various researchers to maintain e- cient, reliable, and low-latency communications between nodes of the UAV network [11,12,22,28,29,32 {34,43 {60]. However ;it is important to consider energy eciency ; as well as the speed of drones for reliable secure commu- nication. Drones often face issues of inadequate energy and computing resources [25, 27, 36, 38, 44, 61 {65]. Re- Communication and Networking Technologies for UAVs: A Survey 3 searchers have given insights to optimize solutions for these problems. Another problem is communication fail- ure due to aerial network jamming. Such interference can be a serious issue. Networks of UAVs are being used now for emergency communication infrastructure and surveillance, as suggested in [44,56,66{72]. A diagram summarizing communication technolo- gies of drones, their linkage with recent technological advancements, and their combined applications are laid out in Fig. 1. The notion is to concisely present how each piece from the left, middle, and right portion can be associated together. For instance, if communication is established between a drone and an ambulance through a sophisticated vehicular communication system, an ar- ti cial intelligence algorithm - running oine on drone or online on cloud - can monitor the paths and deter- mine the best route to provide emergency aid. The left portion of the diagram presents some key attributes of communication technology of drones. The gure also shows the association with the four major disciplines in the middle portion. The association between these two portions alone constitutes a vast amount of research. Along with performance analysis in applications (as shown on the right portion) such as surveillance and emergency aid, the magnitude of scope is nearly un- fathomable. Their technological entanglement will be broken down for further investigation, along with the identi cation of some links which are missing or need further consideration. 1.1 Review of Previous Survey Works In addition to the growing number of new solutions for UAV communication networks in recent years, a num- ber of surveys have been published focusing on UAV communication. These surveys suggested di erent types of technologies to improve the performance of UAV com- munication. A summary of these existing survey and tutorial articles is provided in Table 1. The authors of