Method for terminal to access channel in unlicensed band and device using same method

A user equipment (UE), the UE comprising:

• at least one transceiver configured to transmit and receive a radio signal;
• and
• at least one processor connected to the at least one transceiver,
• wherein the at least one processor is configured to:
• transmit code block groups (CBGs) through a physical uplink shared channel (PUSCH),
• receive downlink control information (DCI) including a new data indicator (NDI) and a code block group transmission information (CBGTI) field, and
• adjust a contention window size,
• wherein, based on that the NDI has not been toggled, ACK/NACK information for the CBGs is provided by the CBGTI field indicating at least one CBG to be retransmitted among the CBGs and the contention window size is adjusted based on the ACK/NACK information,
• wherein, based on that the NDI has been toggled, the contention window size is set to a minimum contention window size for a priority class,
• wherein the ACK/NACK information corresponds to the PUSCH in a reference time resource for a channel occupancy, and
• wherein the reference time resource is a duration of a first transmission burst by the UE within the channel occupancy that contains the PUSCH.

An apparatus, the apparatus comprising:

• at least one memory storing instructions;
• and
• at least one processor connected to the at least one memory, wherein the at least one processor executes the instructions to perform operations comprising:
• transmitting code block groups (CBGs) through a physical uplink shared channel (PUSCH),
• receiving downlink control information (DCI) including a new data indicator (NDI) and a code block group transmission information (CBGTI) field, and
• adjusting a contention window size,
• wherein, based on that the NDI has not been toggled, ACK/NACK information for the CBGs is provided by the CBGTI field indicating at least one CBG to be retransmitted among the CBGs and the contention window size is adjusted based on the ACK/NACK information,
• wherein, based on that the NDI has been toggled, the contention window size is set to a minimum contention window size for a priority class,
• wherein the ACK/NACK information corresponds to the PUSCH in a reference time resource for a channel occupancy, and
• wherein the reference time resource is a duration of a first transmission burst by the apparatus within the channel occupancy that contains the PUSCH.