SPECTRUM ALLOCATION DEVICE

PROBLEM TO BE SOLVED: To search for a frequency spectrum by which a cognitive radio system can be used in a short time.SOLUTION: A spectrum allocation device allocates a usable channel and permissible transmission power of the channel to a second radio device belonging to a second radio system by which a channel group used overlaps that of a first radio system and priority of which is lower than the first radio system. The spectrum allocation device comprises: an area determination unit for selecting a communication area of the first radio device to be determined as an object area; a critical point calculation unit for generating positional information of an intersection point between a border line of the communication area of the first radio device belonging to the object area and a straight line connecting the first radio device and the second radio device corresponding to the border line; a loss calculation unit for calculating a first propagation loss from the second radio device; and a power calculation unit for calculating the usable channel and the permissible transmission power on the basis of the channel used by the first radio device belonging to the object area and a required signal power level, and the first propagation loss.