# Towards 6G Satellite-Terrestrial Networks: Analysis of Air Mobility Operations
## 1 Introduction  
Urban air mobility (UAM) is a subset of advanced air mobility (AAM), and it is defined as safe and efficient air traffic operations for passenger and cargo transport within the urban environment, with an on-board pilot or a remote pilot in command (RPIC) or a completely autonomous unmanned aircraft system (UAS) [1, 2]. Such a technological capability requires a robust communication system (among other systems) capable of operating in a congested urban environment. The UAM system demands a communication system that has good availability, integrity, and security for the safety of its operations in the urban environment. In this paper, we study the communication systems requirements to support UAM operations. To do so, existing and potential communication systems for UAM are reviewed; they include 3 rd Generation Partnership Project (3 GPP) 6G technology [3, 4]. LEO constellations will be used to provide reliable and fast broadband services to the public in the future and improve communication capabilities and efficiency in various fields [5]. In future 6G technology, space-ground-integrated-network, low-Earth-orbit satellites will play an especially important role [6, 7]. Furthermore, this paper elaborates on a performance analysis of the data link for communication between ground stations to unmanned aerial vehicles (UAVs) using link budget analysis and taking weather attenuation and the Doppler effect into consideration. Additionally, the effect of altitude on the quality of service in terms of latency was studied and is presented. These studies will help design robust communication system architectures for UAVs in remote regions. Urban air mobility (UAM) vehicle operations require specialized communication systems that prioritize robustness and efficiency. Central to these requirements is a resilient command and control (C2) data link, responsible for managing critical flight and safety systems, telemetry data, and communication between the UAM vehicle and the ground station [8; 9; 10]. This link must be immune to both unintentional and intentional interference, such as jamming and spoofing, with contingency plans for quick recovery should disruptions occur [11; 12]. Additionally, the communication module on the vehicle should be lightweight to conserve energy, thus enhancing the UAV's range and endurance by allowing more power to be allocated to propulsion systems. UAM communication systems must adapt to the unique challenges posed by the operating environment [13]. They must ensure uninterrupted service across urban [14], rural, or remote terrains at a typical altitude range of 600 to 5000 feet, even necessitating transitions to satellite communications (SATCOM) when terrestrial networks are unavailable [15; 16; 17]. Introducing SATCOMs also brings many challenges, including interference management and resource optimization [18; 19; 20; 21]. High-speed UAV operation requires the system to accommodate Doppler shifts without failure. Additionally, precise location detection is crucial for collision avoidance, while managing interference is vital to prevent potentially catastrophic failures. To maintain operational efficiency and safety, the system must also support minimal signal losses and low latency, ensuring reliable, real-time communication in urban settings. Satellite-terrestrial networks employ an architecture that merges the extensive reach of satellite systems with the high capacity and low latency of terrestrial networks [22]. This approach facilitates coverage extension to remote areas and significantly enhances the performance capabilities of Internet-of-Things (IoT) applications; therefore, it is positioned as a backbone for future smart ecosystems [23]. However, despite these advancements, the specific deployment and optimization of these networks for UAV operations pose unique challenges, particularly in maintaining reliable connectivity in dynamic aerial environments.