A mobile communication
system includes using a mobile terminal, base stations and a
base station control device. Each, each of the base stations cover respective areas for mobile communication service and is capable of relaying a conversation, made by the mobile terminal, by radio communication. The
base station control device observes (or monitors) traffic (i.e., number of calls in progress) with respect to each of the base stations. In response to a conversation start event or a conversation end event that takes place in the mobile terminal which is located in an area of a
base station whose traffic is large, the base
station control device searches a surrounding base
station whose traffic is relatively small. The base
station control device then controls an area of the searched base station to enable radio communication with respect to the mobile terminal. For example, output of the searched base station is increased so that an area of the searched base station is broadened to cover a location of the mobile terminal. Thus, it is possible to avoid occurrence of call failure due to shortage of communication lines.