# UAV-BS Site Planning Based on Circular Coverage Strategy
## 1 Introduction  
With the development of Mobile Communication Technology from its inception to 5 th Generation Mobile Communication Technology (5G), its communication characteristics have changed greatly. The first generation of communication could only provide phone service, and the quality of the communication signal was poor. The data transmission rate was improved from the era of text communication to the era of MMS. It then entered theera of video. 5G opened the door for the integration of communication technology and Internet technology; thus, there have been a variety of new wireless access technologies and evolution technologies. However, for people's increasingly rich demands, there are still plenty of deficiencies.inally, 6 th Generation Mobile Communication Technology (6G) has become a key research and development project in many countries [1; 2; 3]. At present, most of the base stations in 5G networks are deployed on land. This static and single-dimensional communication network may not meet the communication needs of users in the face of special communication scenarios or sudden network paralysis. The 6G communication network will be an unprecedented ultra-flexible and dense network with full dimension and full coverage. It will combine the traditional ground local area network, air network, satellite constellation network and underwater network to realize the global coverage and integration of air, ground, and sea. Especially with the increase in the types and numbers of aerial vehicles with strong mobility and easy deployment, such as helicopters, high-altitude flying boats, and unmanned aerial vehicle (UAVs), the establishment of low-altitude networks with aerial flight base stations as communication nodes to supplement the static network architecture will play a more important role. Compared with other communication networks, the UAV Communication Network (UAVCN) has the advantages of convenience, controllability, and flexibility, which can be used for emergency communication scenarios such as disaster detection and rapid rescue, and can also provide effective communication services for high-density business scenarios such as important conferences and large-scale events. At the same time, UAV technology has also developed rapidly in recent years, with great improvement in manufacturing cost, operational controllability, and body size, which expands the application space of UAV communication in the public and civil field; it is now widely used in smart city traffic management, water conservancy project management, battlefield military information reconnaissance, agricultural and forestry resource management, etc. [4]. Generally, UAVs can be divided into two categories: fixed-wing UAVs and rotorcraft UAVs based on wing configuration [5; 6]. Rotcraft UAVs have the advantages of fast takeoff speed, flexible landing, and the ability to hover at any position in the air. However, they also have the problems of low flight altitude, limited maximum flight speed, small carrying capacity, and short flight distance. Fixed-wing UAVs have a long wingspan and large models, as well as superior flight performance and payload. The disadvantage is that they cannot take off and land vertically, and can only hover but not in the air. In the actual application process, different UAV types are used in the face of different scene requirements. Energy consumption is an important factor affecting the results of site planning. The energy consumption of traditional base stations includes two parts: communication power consumption and cooling system power consumption, among which the communication power consumption, such as radio frequency and baseband processing, is the main consumer. Therefore, greater attention is paid to the optimization of communication energy consumption during the site planning process. Addressing these issues in UAV Base Station (UAV-BS) site planning, this paper proposes a solution based on UAV communication power consumption and employs a geometric method to tackle the problem.