There is a problem that when a closed subscriber group (CSG)
cell (1303) available to subscribers is installed in a
macro cell area (1301), communication cannot be performed due to the interference between a
macro cell (1302) and the CSG cell (1303) in an area (1304) thereof. The CSG cell (1303) that is provided in the CSG cell area (1304) and transmits a downlink
synchronization signal using a radio frame assigns control signals to a first
subframe and a second
subframe among a plurality of subframes constituting the radio frame, and the
macro cell (1302) that is provided in the
macro cell area (1301) and transmits a downlink
synchronization signal using the radio frame assigns control signals to a third
subframe and a fourth subframe, which are shifted from the first subframe and the second subframe by a predetermined number of subframes, respectively, among the plurality of subframes constituting the
radio wave, the CSG cell (1303) and the
macro cell (1302) being configured to perform transmission in synchronization with each other.