# Unmanned Autonomous Intelligent System in 6G Non-Terrestrial Network
## 5 A Case Study of UAV NTN Airborne Network in Mountainous Area
### Design of Field Trial of UAV NTN Network System  
To assess the practicality of a UAV NTN airborne network in mountainous regions for disaster relief operations and natural resource exploration, a thorough field trial is plannedand executed. Here, we introduce the experimental system component and conduct a more in-depth study of the proposed case. In this case, a group of UAVs are utilized to provide airborne network coverage for mountainous regions (Figure 6). To provide emergency coverage and service using NTN communication, UAVs are considered flexible and easy-to-deploy platforms for carrying base stations. In Figure 6, we illustrate the setup of multiple UAVs achieving NTN emergency communication coverage. As for the platform, we select the rainbow CH-4 fixed-wing UAV as the carrier platform for NTN communication, which is developed and manufactured by the China Academy of Aerospace Aerodynamics, an entity under the China Aerospace Science and Technology Corporation (CASC). The take-off weight of CH-4 UAV is 1330 kg with a payload up to 345 kg and the flight endurance is over 40 h. The CH-4 platform is utilized to install 5G base stations and other equipment. In our solution, to support the wireless link from UAVs to the control center/nearby UAV, a satellite transceiver is also installed at the back of the UAV with a transmitting speed of 2 Mbps. Non-terrestrial networks have gained significant attention due to the expansion of large-scale wireless communication networks coverage facilitated by the use of airborne platforms like satellites and UAVs. The network architecture of our field trial is divided into three layers. The top layer consists of a high-capacity communication satellite, which is used to transmit status information from UAVs to the remote control center and to send control instructions to the UAVs. In addition, satellite links are also utilized to maintain communications between UAVs. The middle layer of the network is composed of three interconnected fixed-wing CH-4 UAVs with 5G base stations onboard. The base stations onboard the UAVs are commercial base stations that operate at a frequency of 2.6 GHz, creating a multi-UAV coverage network. This setup is useful for verifying the performance of multi-UAV coverage in different applications and validating the multi-platform use case scenario, as interference may occur at certain radio frequencies in practical applications. The three fixed-wing UAVs are interconnected to each other via satellite networks. The ground layer of the network is utilized for the backhaul of UAV base stations. The UAV  
Figure 6: Overview of UAV airborne network in the case study. equipped with a the base station operating at the frequency of 2.6 GHz, is connected to a ground base station connecting to the UAV ground control center in the airport by means of a fiber optic transmission cable. Furthermore, MEC servers can also be integrated into the UAVs and robots offering low latency task offloading for end users. The purpose of the field trial was to validate the usability of NTN communications for robotics and other applications in mountainous areas for post-disaster relief and rescue scenarios. The UAV NTN network is designed to provide ground communication coverage when ground communication infrastructure is crippled or unavailable. Various kinds of ground user equipment is needed to access the UAV network in disaster relief operations. In the field trials, the selected ground user equipment (UE) of the air-to-ground network include quadruped locomotion robots, rotary wing UAVs and cell phones. Robots are widely used in scientific studies and industry for surveillance, area perception, and other autonomous tasks, while in disaster management scenarios, multi-spectral cameras are mounted on the robot to spot the locations of wildfire points or people trapped after earthquakes.