In a radio communication system having narrow-band up- and down-link radio channels and a wide-band down-link radio channel, when a radio terminal is to receive data through the wide-band down-link radio channel, the narrow-band up- and down-link radio channels are assigned to the radio terminal in advance. With this operation, communication an be performed by using the wide-band down-link radio channel. In addition, the narrow-band up- and down-link radio channels can be used as radio channels for performing control to efficiently transmit data by using the wide-band down-link radio channel.