Radio terminal, radio base station, channel signal forming method and channel signal receiving method

A user equipment, (UE) comprising:

• an information size determination section configured to determine a first basic information size of control information mapped on a UE specific search space in a first component carrier, the first basic information size of the control information mapped on the UE specific search space being different from a second basic information size of control information mapped on a common search space in the first component carrier;
• and
• a receiver configured to monitor the control information mapped on the UE specific search space based on the determined first basic information size,
• wherein when uplink allocation information is absent in the first component carrier,
• the first basic information size is determined according to an information size determined from a downlink bandwidth of the first component carrier.

A physical downlink control channel (PDCCH) reception method performed by a reception apparatus, comprising:

• determining a first basic information size of control information mapped on a user equipment (UE) specific search space in a first component carrier, the first basic information size of the control information mapped on the UE specific search space being different from a second basic information size of control information mapped on a common search space in the first component carrier;
• and
• monitoring the control information mapped on the UE specific search space based on the determined first basic information size,
• wherein when uplink allocation information is absent in the first component carrier, the first basic information size is determined according to an information size determined from a downlink bandwidth of the first component carrier.

A physical downlink control channel (PDCCH) reception method performed by a reception apparatus, comprising:

• determining a first basic information size of control information mapped on a UE specific search space in a first component carrier;
• and
• monitoring the control information mapped on the UE specific search space based on the determined first basic information size,
• wherein a first determination method for determining the first basic information size is different from a second determination method for determining a second basic information size of control information mapped on a common search space in the first component carrier, and
• the first determination method for determining the first basic information size is different from a third determination method for determining a third basic information size of control information mapped on a search space in a second component carrier that is different from the first component carrier.