The present invention relates to a device that includes a radio network control device operable to control a plurality of radio base stations. Also included is a grouping processing unit operable to group into a same group many mobile devices that perform handover to a specific radio base station in a predetermined period. Furthermore, the device includes an identification information notifying unit operable to, when a mobile device performs handover to the radio base station, notify the radio base station of identification information of the mobile device and identification information of one or more other mobile devices belonging to the same group.