Base station apparatus, terminal apparatus, transmission method, and reception method

A communication apparatus comprising:

• a receiver which, in operation, receives physical resource block (PRB) pair information related to PRB pairs;
• and
• circuitry which, in operation, specifies, based on the PRB pair information, at least one of (i) a first search space for localized transmission, which is comprised of a plurality of first control channel elements (CCEs), each first CCE consisting of four enhanced resource element groups (EREGs) in one PRB pair, and (ii) a second search space for distributed transmission, which is comprised of a plurality of second CCEs, each second CCE consisting of four EREGs distributed among a plurality of PRB pairs, wherein each of the one or the plurality of PRB pairs is divided into sixteen EREGs,
• wherein:
• the receiver, in operation, further receives assignment information mapped to at least one of the first search space and the second search space;
• and
• four EREGs that are provided in one PRB pair, which form a portion of EREGs that correspond to a subset of the plurality of second CCEs, are identical to four EREGs that correspond to one first CCE of a subset of the plurality of first CCEs, and four EREGs that are provided in another PRB pair, which form another portion of the EREGs that correspond to said subset of the plurality of second CCEs, are identical to four EREGs that correspond to another first CCE of said subset of the plurality of first CCEs.