A first terminal generates a first scheduling request signal including information about first data resources for data transmission when the first terminal tries to reserve the first data resources. The first terminal generates a first scheduling request indication signal providing notification that the first scheduling request signal is to be transmitted. The first terminal transmits the first scheduling request indication signal through a first request subslot included in a first scheduling request resource before transmitting the first scheduling request signal. The first terminal transmits the first scheduling request signal through a second request subslot included in the first scheduling request resource.