A base station for listen-before-talk, LBT, operation in a wireless communication network, the base station comprising: a transceiver configured to transmit and receive a signal; and at least one processor configured to: trigger an LBT request to transmit, to a terminal, an uplink, UL, grant and a downlink, DL, data on an unlicensed band; determine an adaptive contention window, CW, size comprising a predetermined minimum value and maximum value for transmitting the DL data; perform a first LBT operation for the DL data in accordance with the adaptive CW size; perform a second LBT operation for the UL grant; wherein, in case that the second LBT operation is finished earlier than the first LBT operation, the at least one processor is further configured to: multiplex the DL data into a transmission of the UL grant in one subframe; and control the transceiver to transmit the UL grant multiplexed with the DL data to the terminal, and wherein, in case that the first LBT operation is finished earlier than the second LBT operation, the at least one processor is further configured to: multiplex the UL grant into a transmission of the DL data in one subframe; and control the transceiver to transmit the DL data multiplexed with the UL grant to the terminal. a transceiver configured to transmit and receive a signal; and at least one processor configured to: trigger an LBT request to transmit, to a terminal, an uplink, UL, grant and a downlink, DL, data on an unlicensed band; determine an adaptive contention window, CW, size comprising a predetermined minimum value and maximum value for transmitting the DL data; perform a first LBT operation for the DL data in accordance with the adaptive CW size; perform a second LBT operation for the UL grant; wherein, in case that the second LBT operation is finished earlier than the first LBT operation, the at least one processor is further configured to: multiplex the DL data into a transmission of the UL grant in one subframe; and control the transceiver to transmit the UL grant multiplexed with the DL data to the terminal, and wherein, in case that the first LBT operation is finished earlier than the second LBT operation, the at least one processor is further configured to: multiplex the UL grant into a transmission of the DL data in one subframe; and control the transceiver to transmit the DL data multiplexed with the UL grant to the terminal. trigger an LBT request to transmit, to a terminal, an uplink, UL, grant and a downlink, DL, data on an unlicensed band; determine an adaptive contention window, CW, size comprising a predetermined minimum value and maximum value for transmitting the DL data; perform a first LBT operation for the DL data in accordance with the adaptive CW size; perform a second LBT operation for the UL grant; wherein, in case that the second LBT operation is finished earlier than the first LBT operation, the at least one processor is further configured to: multiplex the DL data into a transmission of the UL grant in one subframe; and control the transceiver to transmit the UL grant multiplexed with the DL data to the terminal, and multiplex the DL data into a transmission of the UL grant in one subframe; and control the transceiver to transmit the UL grant multiplexed with the DL data to the terminal, and wherein, in case that the first LBT operation is finished earlier than the second LBT operation, the at least one processor is further configured to: multiplex the UL grant into a transmission of the DL data in one subframe; and control the transceiver to transmit the DL data multiplexed with the UL grant to the terminal. multiplex the UL grant into a transmission of the DL data in one subframe; and control the transceiver to transmit the DL data multiplexed with the UL grant to the terminal.