User terminal, radio base station and radio communication method

A radio base station that can communicate with a user terminal that uses six or more component carriers, the radio base station comprising:

• a transmission section that transmits a DL signal;
• a receiving section that receives a UL control signal, which includes a delivery acknowledgement signal in response to the DL signal;
• and
• a control section that controls configuration of a format that the user terminal applies to the UL control signal,
• wherein the control section configures, in the use terminal, a foi iat, having large capacity in comparison to a PUCCH format of an existing system in which the number of component carriers to be configured is five or less.

A radio communication method in a user terminal that can communicate by using six or more component carriers, the radio communication method comprising the steps of:

• receiving a DL signal;
• receiving a UL control signal, which includes a delivery acknowledgement signal in response to the DL signal;
• and
• controlling a format to apply to an UL control signal,
• wherein a format, having large capacity in comparison to a PUCCH format of an existing system in which the number of component carriers to be configured is five or less, is applied to the UL control signal.