Fuger, KonradKonradFugerMelzer, BjörnBjörnMelzerHesse, FabianFabianHesseRossbach, AndreasAndreasRossbachFuchs, MatthiasMatthiasFuchsKuladinithi, KoojanaKoojanaKuladinithiMarks, TobiasTobiasMarksOikonomopoulos, ChristosChristosOikonomopoulosStavrou, E.E.StavrouNil, AndreasAndreasNilLaiacker, MaximilianMaximilianLaiackerBrinkmeyer, JörgJörgBrinkmeyerTimm-Giel, AndreasAndreasTimm-Giel2025-08-202025-08-202025-03IEEE International Conference on Pervasive Computing and Communications Workshops and other Affiliated Events, PerCom Workshops 2025https://hdl.handle.net/11420/57078Providing reliable communication services for Unmanned Aircraft Systems (UASs) is one of the remaining challenges hindering the deployment of large-scale UAS operations. In this paper, we describe the design and implementation of a multi-link modem developed to fulfill current and future communication needs. This modem combines LTE/5G with 868MHz based long-range communication, an Iridium satellite connection, and C-V2X to provide direct UAS to UAS communication with a low latency and a high data rate. To realize this, hardware components were selected and integrated into a communication stack. Custom software was developed to operate the hardware and intelligently utilize all available communication links. Real-world flight tests were conducted with the developed modems mounted on state-of-the art commercial UASs. In this work, we present an in-depth analysis of the performance of the direct C-V2X communication which is one of the proposed technologies for future UAS communication. Our results show that a communication range over 2km is achieved at an end-to-end delay of around 60ms.enC-V2XUASUAVUTMTechnology::600: TechnologyConference Paper10.1109/PerComWorkshops65533.2025.00088Conference Paper