An integrated circuit includes generation circuitry and transmission circuitry. The generation circuitry uses a reference size for a search space to generate downlink control information (DCI) in a first DCI format used for sidelink communications. The transmission circuitry transmits the DCI in the first DCI format mapped on the search space. When a second DCI format used for base station communications is mapped on the search space and the second DCI format is larger than the first DCI format, the reference size for the search space is based on the second DCI format. When a third DCI format used for sidelink communications is mapped on the search space and the third DCI format is larger than the first DCI format, and the second DCI format larger than the third DCI format is not mapped on the search space, the reference size is based on the third DCI format.