Receiver device, transmitter device, reception method, and transmission method

A transmission apparatus comprising:

• a precoder which, in operation, performs precoding on a control signal mapped to one of a plurality of mapping candidates defined by a search space of a subframe, using one of a first transmission method and a second transmission method in accordance with an aggregation level configured for each of the plurality of mapping candidates, the first transmission method using a single antenna port to perform precoding and the second transmission method using multiple antenna ports to perform transmission diversity;
• and
• a transmitter which, in operation, transmits the precoded control signal,
• wherein the mapping candidates are assigned numbers in ascending order from a mapping candidate corresponding to a lower aggregation level,
• the transmitter transmits a first number assigned to a mapping candidate corresponding to a position of switching between transmission methods among the numbers assigned to the plurality of mapping candidates, and
• blind decoding is performed on a mapping candidate assigned a number lower than the first number using the first transmission method and is performed on a mapping candidate assigned a number equal to or greater than the first number using the second transmission method, at a reception apparatus that receives the transmitted control signal.