Abstract: A device to determine a position of an object movable relative to a vehicle, wherein at least one vehicle-based communication unit is arranged on the outside of the vehicle, which communicates via radio waves with at least one object-based communication unit, and the at least one vehicle-based communication unit is coupled with a processing unit which is designed to determine the position of the object relative to a vehicle-centered coordinate system from the communication signals. The communication units are designed to determine distance between them by determining time-of-flight, and the processing unit is designed to determine the position of the object in the coordinate system by trilateration from at least two distance values determined based on the communication between at least three communication units.