The increasing use of Uncrewed Aerial Vehicles (UAVs) for tasks in urban environments during recent years has driven the need for reliable communication systems and precise relative positioning capabilities. The mFund project SKADRO (Scalable Drone Communication Systems for U-space areas) aims to tackle reliable UAV communication by utilizing LTE, particularly in low-level airspace and U-Space, addressing challenges such as cellular network congestion and the effects of urban infrastructure on signal propagation. The latter also affects the accuracy of Global Navigation Satellite Systems (GNSS) used for absolute and relative positioning, and effects include multipath effects, non-line-of-sight propagation or shadowing. This paper presents results from a flight test that has been conducted at the Technische Universität Berlin, where three UAVs were operated under U-space conditions. The UAVs were equipped with a custom sensor payload consisting of a 4G/5G communication device developed during the mFund project SUCOM (Superior UTM Communication System), a camera, and a custom sensor box consisting of a GNSS receiver, a Software- Defined Radio, an ADS-B transceiver, an Ultrawide-band Radio, and a laser altimeter. During this test, the U-space Service Provider (USSP) b.r.m. IT Aerospace provided a recognized air picture based on ADS-B, which is compared to the position information transmitted through the cellular network. Real-time data, including video streams, were transmitted to Fraunhofer Heinrich-Hertz-Institute´s TimeLab for real-time monitoring and analysis of beyond-visual-line-of-sight (BVLOS) capabilities of the UAV operations within the U-space environment. In addition to vehicle-to-infrastructure (V2I) communication, the study explores the feasibility of direct vehicleto- vehicle (V2V) communication using the Automatic Dependent Surveillance - Light (ADS-L) as proposed by the European Union Aviation Safety Agency (EASA). While this standard utilizes the short-range 860 (SRD- 860) frequency band, rather a version transmitted over the cellular network is used. The findings highlight the potential advantages of V2V communication in urban environments, where direct communication between UAVs might enhance operational reliability and safety.
Frickenstein et al. (Fri,) studied this question.