# Experimental Study on LTE Mobile Network Performance Parameters for Controlled Drone Flights
## 1 Introduction  
More and more innovative and advanced technologies are being introduced into modern-day life. One such technology that has recently experienced an increase in topicality is drones, also known as unmanned aerial vehicles (UAVs). The manufacture of UAVs and their integration within the new industrial sphere show an increase in potential and business aspects with current forecasts indicating a market share of around USD 100 billion in years to come [1]. The realization potential of UAVs is vast as new applications are constantly being invented and presented. There are multiple areas in which UAVs have especially been used lately. Some of those are monitoring [2; 3; 4; 5], inspections [6; 7], examinations [8; 9], mapping [10; 11], agriculture [10; 12], surveillance [13; 14], logistics [15; 16], the transport sector [8; 14; 17], military industry [18; 19], communications and newsgathering [11; 20] and media, as well as solutions for research needs [20; 21]. Also, another type of application that may encounter a high number of requests for UAVs in the upcomingyears is package delivery [22; 23]. Within the U.S., multiple companies have recently been investigating the package delivery capabilities of UAVs [11]. Overall, in the civilian and governmental sector, one of the crucial use cases is disaster response and recovery [24; 25; 26], thus ensuring a rapid reaction time by the response teams, so that rescuers and special services utilize real-time information observed prior to their arrival [27]. Typically, the operational scheme of how UAVs are used is by realizing a line-of-sight (LOS) local type of connection between the UAV and its operator--the end-user. Therefore, the communication link with the UAV is also local, typically Wi-Fi-based technology, and tends to operate by using unlicensed frequency bands. This application limits the operation of those UAVs to regions where the UAV can be used locally [28; 29], without realizing necessary coordination with the responsible institution that ensures the necessary permits. However, when a licensed frequency spectrum is used, research conducted [30] regarding the available radio link technologies that are utilized in UAV operations indicated three alternatives or choices for UAV datalink coverage. Such techniques include terrestrial mobile 4G/long-term evolution (LTE) networks, satellite links within the allocated spectrum, or 5G networks (if available and applicable) that are adapted to air-ground usage, or UAV terrestrial networks using licensed spectrum in very high frequency (VHF) or ultra-high frequency (UHF) bands in specific situations. Furthermore, the realization of UAVs in civilian and commercial fields has shown essential topicality in recent years. However, for advanced applications of UAVs, an extended and increased, beyond visual-line-of-sight, configuration is required. In comparison to the typical LOS realizations, such extended services require fulfillment of the regulatory standards; thus, a radio communication link has to be established correctly and should maintain stable and reliable link connections. As a means of transmission link media, long-term evolution UMTS (LTE) is a core standard in cellular systems for the radio communication links of UAVs [31]. Multiple civil applications for drones in different industries have led to an increasing demand for a stable and suitable level of performance in wireless connectivity to UAVs. Hence, mobile networks ensure a relatively reliable base for secure wide-area connectivity to such devices. However, there still is a requirement for ubiquitous connectivity for a wide range of other user equipment (UE) that utilizes the available frequency spectrum that needs to be taken into account. For instance, sensors, driverless cars, and enhanced mobile broadband (eMBB) devices. All of these require the use of airborne communication capabilities.