The present invention enables assignment to a terminal a sub-band having satisfactory communication quality. A reference-signal reception unit receives from a terminal a reference signal spreading over sub-bands. A communication-quality measurement unit measures the communication quality of each of the sub-bands on the basis of the reference signal. A sub-band assignment unit assigns one of the sub-bands to the terminal on the basis of the communication quality, for the terminal to perform wireless communication with the communication device. A reference-signal transmission unit transmits to the communication device a reference signal spreading over the sub-bands. A sub-band-assignment-information reception unit receives information on one of the sub-bands which is assigned to the terminal by the communication device on the basis of the reference signal. A data transmission unit transmits data to the communication device through the sub-band assigned to the terminal.