A user equipment, an apparatus, and a method receive from a base station configuration information on a carrier aggregation where a Licensed-Assisted Access (LAA) secondary cell using unlicensed frequency is utilized, configure the carrier aggregation based on the configuration information, receive from the base station information indicating whether uplink data transmission via the LAA secondary cell is allowed, and transmit uplink data via the LAA secondary cell only in response to receiving the information indicating that uplink data transmission via the LAA secondary cell is allowed.