1. A radio terminal configured to be capable of executing a sidelink operation in which a direct device-to-device interface is used, the radio terminal comprising:a controller configured to:
set a plurality of sidelink gaps, each corresponding to each of a plurality of frequencies to which a neighbor cell different from a serving cell belongs
execute the sidelink operation during each of the set plurality of sidelink gaps at each of the plurality of frequencies; and
exempt a communication between the radio terminal and the serving cell during the sidelink gaps, and
a transmitter configured to transmit, to the serving cell, a frequency list indicating frequencies requesting releasing sidelink gaps each corresponding to each of the frequencies of the frequency list, among the plurality of frequencies when the radio terminal is not interested in the sidelink operation at the frequencies of the frequency list, wherein
the controller is configured to autonomously release the sidelink gaps corresponding to the frequencies of the frequency list,
the transmitter is configured to be permitted to transmit a measurement report even during the sidelink gaps, and
the controller is configured to start monitoring a control signal transmitted from the serving cell in response to transmitting a measurement report.