In the present disclosure, a user equipment (UE) receives a uplink (UL) grant for a wide band, the wide band i) being wider than a predetermined value, ii) operating on an unlicensed band and iii) including multiple subbands; measures channel occupancy for the wide band; determines whether to generate a medium access control (MAC) protocol data unit (PDU) in units of the whole wide band or in units of subband, based on the measured channel occupancy; generates the MAC PDU in units of the whole wide band or in units of subband; performs clear channel assessment (CCA) per subband; and transmits the generated MAC PDU via at least one subband where the CCA is successful.