Radio communication system, base station apparatus, mobile station apparatus, radio communication method, and program

A base station apparatus that communicates with a mobile station apparatus that monitors a physical downlink control channel in a plurality of search spaces on each of at least one downlink component carrier of a plurality of downlink component carriers, the base station apparatus comprising:

• an associating unit that associates each of the plurality of search spaces with one of the downlink component carriers, which are controlled by downlink control information that is transmitted using the physical downlink control channel;
• and
• a transmission processing unit that performs a process of transmitting the downlink control information using the physical downlink control channel arranged in the associated search space.

A base station apparatus that communicates with a mobile station apparatus that monitors a physical downlink control channel in a plurality of search spaces on each of at least one downlink component carrier of a plurality of downlink component carriers, wherein the base station apparatus:

• associates each of the plurality of search spaces with one of the downlink component carriers, which are controlled by downlink control information that is transmitted using the physical downlink control channel;
• and
• performs a process of transmitting the downlink control information using the physical downlink control channel arranged in the associated search space.

A mobile station apparatus that communicates with a base station apparatus and monitors a physical downlink control channel in a plurality of search spaces on each of at least one downlink component carrier of a plurality of downlink component carriers, wherein:

• each of the plurality of search spaces is associated with one of the downlink component carriers, which are controlled by downlink control information that is transmitted using the physical downlink control channel, by the base station apparatus;
• and
• the mobile station apparatus comprises a reception processing unit that performs a process of receiving the downlink control information, which is transmitted using the physical downlink control channel arranged in the associated search space.

A communication method for a base station apparatus that communicates with a mobile station apparatus that monitors a physical downlink control channel in a plurality of search spaces on each of at least one downlink component carrier of a plurality of downlink component carriers, the communication method comprising:

• a step of associating each of the plurality of search spaces with one of the downlink component carriers, which are controlled by downlink control information that is transmitted using the physical downlink control channel;
• and
• a step of performing a process of transmitting the downlink control information using the physical downlink control channel arranged in the associated search space.