A corresponding table between a number of a cell and a main base station (102) accommodating the cell is prepared in a node (wireless network control apparatus (101) or main base station (102)) within a radio access network. When a terminal (104) is moved and enters an overlapped area of cells (a) and (b) from an original cell (a), in the case that a main base station (102a) to which the terminal (104) was connected in the cell (a) can accommodate the cell (b) that the terminal (104) has entered, the sub base station (103b) is connected to the main base station (102a), and site diversity is performed in the main base station (102a). Thus, when site diversity is performed between main base stations in a radio access network using a base station in which a baseband processing section is separated from a radio transmission/reception section, traffic flowing between the wireless network control apparatus and the base station is reduced.