Frequency assignment device, frequency assignment method and wireless communication system

A frequency assignment device used for a communication system in which a second system utilizes a radio wave of a frequency that is among radio waves of frequencies usable to a first system and that is not used by the first system in terms of time or space, the frequency assignment device comprising:

• a processor configured to select a first propagation scheme when a distance over which a radio wave transmitted from a transmission device in the second system at a frequency not used by the first system can travel from a position of the transmission device without being blocked by an obstruction is greater than a prescribed threshold, and to select a second propagation scheme resulting in a propagation distance smaller than a propagation distance of the first propagation scheme when the distance over which the radio wave can travel is smaller than the prescribed threshold, and to calculate a propagation distance of the transmission radio wave by using a propagation scheme selected by the selection unit, and to determine that the second system can utilize the transmission radio wave when a propagation distance of the transmission device does not reach a propagation scope of a radio wave of a frequency that can be used by the first system.