Method and device for transmitting uplink in unlicensed band

1. A method for uplink transmission in a wireless communication system, the method comprising:

receiving, by a wireless device, information regarding a main-pool for uplink transmission in an unlicensed band from a base station;

determining, by the wireless device, an idle sub-pool by performing clear channel assessment (CCA) on a plurality of sub-pools in the main-pool in the unlicensed band;

transmitting, by the wireless device, an uplink transport block to the base station by using the determined idle sub-pool in the unlicensed band; and

receiving, by the wireless device, an acknowledgement (ACK)/not-acknowledgement (NACK) signal for the uplink transport block from the base station,

wherein the ACK/NACK signal is included in downlink control information (DCI), and

wherein the DCI further includes information for stopping the uplink transport block, resuming the uplink transport block, an uplink transmission probability and/or information for adjusting a CCA parameter used for a contention based uplink transmission, a contention based uplink retransmission, and a contention based uplink initial transmission.

2. The method of claim 1 , further comprising:

randomly selecting, by the wireless device, a sub-pool for performing the CCA from the plurality of sub-pools.

3. The method of claim 1 , wherein the main-pool comprises a plurality of subframes.

4. The method of claim 3 , wherein the CCA is performed at a start time of each of the plurality of subframes.

5. The method of claim 1 , further comprising:

transmitting a preamble used to identify the sub-pool before the uplink transport block.

6. The method of claim 5 , wherein the preamble is generated based on an identifier of the wireless device.

7. A device for uplink transmission in a wireless communication system, the device comprising:

a transceiver configured to transmit and receive a radio signal; and

a processor operatively coupled to the transceiver and configured to:

control the transceiver to receive information regarding a main-pool for uplink transmission in an unlicensed band from a base station;

determine an idle sub-pool by performing clear channel assessment (CCA) on a plurality of sub-pools in the main-pool in the unlicensed band;

control the transceiver to transmit an uplink transport block to the base station by using the determined idle sub-pool in the unlicensed band; and

control the transceiver to receive an acknowledgement (ACK)/not-acknowledgement (NACK) signal for the uplink transport block from the base station;

wherein the ACKJNACK signal is included in downlink control information (DCI), and

wherein the DCI further includes information for stopping the uplink transport block, resuming the uplink transport block, an uplink transmission probability and/or information for adjusting a CCA parameter used for a contention based uplink transmission, a contention based uplink retransmission, and a contention based uplink initial transmission.

8. The device of claim 7 , wherein the processor is configured to randomly select a sub-pool for performing the CCA from the plurality of sub-pools.