# Experimental Study on LTE Mobile Network Performance Parameters for Controlled Drone Flights
## 3 Analysis of the Mobile Network Performance Parameters for UAV Application  
The mobile network architecture is usually developed to provide a stable connection for multimedia traffic transfer for a higher number of users over the longest possible distance without mobile cell interference; this task is always a balance between the requirements. To avoid interference and increase network performance, mobile operators are applying different approaches such as considering environmental properties, the relief, potential number of users, limitations to cell capacity, antennas' possible frequency ranges and radiated power, and antennas' spatial distribution including altitudes. Common mobile network user equipment includes mobile phones and different IoT devices, such as sensors, actuators, and other smart environment elements which are spatially distributed near ground level, while antennas are mostly placed at 15-30 m (city) and 30-100 m (rural area) altitudes and are directed at ground level, to avoid different cells interfering with each other at ground level, Figure 1.  
Mobile network application for drone flight control and management has other requirements for the mobile network infrastructure, such as stable connections for multimedia  
Figure 1: Potential drone flight trajectory and interfering antenna placement. traffic transfer at different altitudes and low cell interference not only around the ground but also at higher altitudes, which contradicts the requirements for the usual mobile network end users. The mobile cells' mutual interference increases with the altitude increase, as, for example, was shown in [43; 44]. Therefore, there is a challenge in the simultaneous usage of mobile networks for on-the-ground users and drones. Evaluation of the existing mobile network performance suitability for mobile network applications for controlled drone flight could answer this question or provide information for next-generation mobile network design. As drone flight should be safe for all other users, persons, living things, and infrastructure objects, it requires reliable data transmission, commands, different sensor readings, and image translation. To be able to measure and evaluate network availability in the airspace, several important KPI parameters of the mobile network should be defined and justified by the drone-managing requirements for data transmission performance. According to 3 GPP [43], ACJA [45], and industry standards, data transmission parameters such as DL/UL and latency are defined and used in network measurement data analyses for communication performance evaluation, as well as having been analyzed in previous works [28; 37; 31]. However, different types of transmitted data have different sensitivities to communication-link degradation and, therefore, are observed separately. It should be noted that, according to [45], downlink (DL) and uplink (UL) terms are used as their typical meanings as they are used for cellular communications, unlike, for instance, in the field of aviation. The downlinks, in essence, are the transmissions carried out by the cellular communication tower and finished by the receiver party--UE. Uplink, in contrast, is used to describe the returning data that is sent from the UAV. UAVs may use a variety of flight command and control modes. Command and control (C2) communications refer to the two-way communication, which may include video, required to control the operation of the UAV itself. C2 messages may be communicated with the UAV controller, the UTM, or both and may or may not be periodic. UAV controller and UTM communications may happen at essentially the same time with different required QoS. Any mission-specific communication (e.g., HD video for area surveillance), if required, is additional. To set the KPI for DL/UL and latency, we need to observe the data-type categories of the UAV's transmitted data.