The present invention can improve a reception quality of mobile stations
and utilize radio resources effectively, by resolving the problem caused
when the conventional multicast communications system. The present
invention relates to a radio communications system for transmitting same
data to a plurality of cells via at least one base station and performing
a soft combining or a selective combining on the same data received by a
mobile station. The radio communications system includes a controlling
unit configured to set up a cycle at which synchronization processing on
transmission timing of the same data among the plurality of cells is
performed, or an accuracy by which the synchronization processing is
performed, for each control apparatus which performs the synchronization
processing.