A radio network controller in a mobile communication network detects characteristics of mobile devices that are wireless connected to a radio base station managed by the radio network controller. The radio network controller decides whether the mobile devices can be classified into at least one group according to the detected characteristics. When it is decided that the mobile devices can be classified into at least one group, radio base stations to which the mobile devices can be wireless connected are changed according to the classified group so that radio resources in the radio base stations can be uniformly used. By sharing the radio resources owned by a radio base station, the radio resources under the control of the radio network controller can be effectively utilized.