Radio communication system, user terminal, radio base station apparatus and radio communication method

A radio base station apparatus that coordinates with another radio base station apparatus and performs coordinated multiple point transmission/reception with a user terminal, the radio base station apparatus comprising:

• a determining section configured to determine a reporting mode that matches channel state information which the user terminal feeds back using a physical uplink control channel;
• a transmission section configured to report the determined reporting mode to the user terminal;
• a receiving section configured to receive channel state information of multiple cells, which the user terminal allots and transmits in multiple subframes, in accordance with the reported reporting mode, via a physical uplink shared data channel;
• and
• an updating section configured to update the channel state information using the channel state information of multiple cells that is allocated and received in multiple subframes.

A radio communication method for a plurality of radio base station apparatuses and a user terminal that is configured to be able to perform coordinated multiple point transmission/reception with the plurality of radio base station apparatuses, the radio communication method comprising the steps of:

• at the user terminal, generating feedback information such that channel state information of multiple cells is allotted to a plurality of subframes and transmitted;
• at the user terminal, feeding back the generated feedback information to the radio base station apparatus of one of multiple coordinated points, using a physical uplink shared data channel;
• and
• at the radio base station apparatus, updating the channel state information using the channel state information that is allotted in the plurality of subframes and fed back from the user terminal.