Cooperative Navigation for Urban Air Mobility Utilizing Ad-hoc Communications - An Analysis of Feasibility and Algorithmic Characteristics Using the Example of DroneCAST

Currently, urban air mobility (UAM) is an active field of research, which investigates the use of small aircraft with varying levels of autonomy to realize multi-modal transport in urban areas for both passengers and cargo. In order to use UAM concepts, a navigation system capable of providing precise and accurate state estimates in urban environments is required. Global navigation satellite systems (GNSSs) are used for navigation in a variety of scenarios. However, buildings and infrastructure in urban settings lead to signal occlusions and a rich multipath environment, which limits the effectiveness of these systems. Cooperative navigation, in which users exchange information to estimate their states, based on ad-hoc communication is an attractive backup system or alternative to GNSS in these environments. We propose a cooperative navigation system based on Drone Communication and Surveillance Technology (DroneCAST), which is a communication system currently undergoing development at the German Aerospace Center (DLR). Based on previous research into cooperative navigation, we evaluate and adapt algorithms for cooperative navigation for UAM. In addition, the use of relative and absolute coordinate systems, cooperative measurements, and the impact of these on the overall system are discussed. The results of this theoretical study indicate that the utilization of ad-hoc communication for cooperative navigation in a UAM context is a promising approach. It is likely to provide sufficient precision and accuracy for operations in an urban environment. In order to optimize its performance, the use of absolute coordinates is recommended. Furthermore, the types of cooperative measurements considered by the system should be chosen based on the current context, specifically the density of participants and the distances between them.