Wireless communication for vehicles is an emerging trend in the automotive and drone industries, offering solutions to pressing issues such as traffic congestion and road or air accidents. Within the framework of the Third Generation Partnership Project (GPP3), vehicle communication is classified as vehicle-to-everything (V2X) communication, encompassing vehicle-to-infrastructure (V2I), vehicle-toperson (V2P), and vehicle-to-vehicle (V2V) communication. V2V communication, in particular, presents diverse applications, including collision avoidance, in-car Internet access, and autonomous driving. The primary objective of vehicle wireless communication is to enhance safety, necessitating low latency and high reliability in such communications.To facilitate direct communication, specialized narrowband short-range communication (DSRC) protocols are employed. Nevertheless, these protocols exhibit functional limitations and fall short of delivering optimal outcomes. Furthermore, DSRC faces restrictions in terms of spectrum availability and data transmission, relying on a 5.9 GHz bandwidth for multiple access control (MAC). However, in CSMA mode and on heavily trafficked roads, its effectiveness diminishes. Additionally, the deployment and operation of DSRC infrastructure, such as Roadside Units (RSUs), incur significant expenses.To address these challenges, the utilization of cellular relay in vehicle communication, along with the application of cellular networks such as LTE and 5G, has been proposed. The 3GPP group has defined several crucial scenarios for V2X and V2V communications, encompassing both direct mode and cellular relay mode. In the direct communication mode, vehicles communicate directly with each other. Conversely, in the cellular relay mode, messages are initially transmitted to the cellular terminal (cellular relay) through a remote connection and suBsequently relayed to the destination device via another remote connection. In the following discussion, drones are employed as cellular relays, and the impacts of drone height, car density, and vehicle-to-vehicle communication are explored. Moreover, the influence of increasing the minimum requested rate on the power and bandwidth allocated by the unmanned aerial vehicle (UAV) to the vehicle is examined.
