A radio terminal according to one embodiment is used in a mobile communication system supporting uplink transmission using an unlicensed spectrum. The user terminal comprises a controller configured to perform LBT (Listen-Before-Talk) before the uplink transmission. The controller applies a first LBT scheme to the LBT, in response to reception of information indicating the first LBT scheme from a base station. The controller applies a second LBT scheme to the LBT, in response to reception of information indicating the second LBT scheme with a shorter LBT time interval than the first LBT scheme, from the base station.