Method, device, and system for channel access in unlicensed band

A wireless communication method of a base station for performing downlink transmission in a specific cell, the wireless communication method comprising:

• transmitting a transmission including a physical downlink shared channel(PDSCH)(s) to an User Equipment(UE)(s);
• receiving from the UE(s) a hybrid automatic repeat request acknowledgment(HARQ-ACK) feedback(s) corresponding to the PDSCH(s) on the specific cell;
• and
• adjust a contention window size according to the HARQ-ACK feedback(s),
• wherein each of the PDSCH(s) is based on the TransportBlock(TB) or a Code Block Group(CBG),
• wherein the HARQ-ACK feedback(s) includes at least one of a first HARQ-ACK feedback for a PDSCH based on the CBG or a second HARQ-ACK feedback for a PDSCH based on the TB,
• wherein each bit of the second HARQ-ACK feedback corresponds to each TB,
• wherein N bit(s) of the first HARQ-ACK feedback correspond to CBGs included in a TB,
• wherein the N is a maximum number of CBGs for the TB configured in each of the UE(s),
• wherein the contention window size is increased or reset to a minimum value according to whether one of a first condition for the first HARQ-ACK feedback and a second condition for the second HARQ-ACK feedback is satisfied,
• wherein the first condition is whether a ratio of bits indicating ACK in the first HARQ-ACK feedback is equal to or greater than a specific ratio, and
• wherein the second condition is whether a number of bits indicating ACK in the second HARQ-ACK feedback is one or more.

A User Equipment (UE) for receiving downlink transmission in a specific cell, the UE comprising:

• a communication module;
• and
• a processor configured to control the communication module,
• wherein the processor is configured to:
• receive a physical downlink shared channel (PDSCH) from a base station, and
• transmit a hybrid automatic repeat request acknowledgement (HARQ-ACK) feedback in response to the PDSCH to the base station,
• wherein a contention window size for reception of a next PDSCH is adjusted based one or more HARQ-ACK feedbacks transmitted in response to the PDSCH, and
• wherein the PDSCH is based on a Transport Block (TB) or a Code Block Group (CBG),
• wherein the one or more HARQ-ACK feedbacks includes at least one of a first HARQ-ACK feedback for a PDSCH based on the CBG or a second HARQ-ACK feedback for a PDSCH based on the TB,
• wherein each bit of the second HARQ-ACK feedback corresponds to each TB,
• wherein N bit(s) of the first HARQ-ACK feedback correspond to CBGs included in a TB,
• wherein the N is a maximum number of CBGs for the TB configured in the UE,
• wherein the contention window size is increased or reset to a minimum value according to whether one of a first condition for the first HARQ-ACK feedback and a second condition for the second HARQ-ACK feedback is satisfied,
• wherein the first condition is whether a ratio of bits indicating ACK in the first HARQ-ACK feedback is equal to or greater than a specific ratio, and
• wherein the second condition is whether a number of bits indicating ACK in the second HARQ-ACK feedback is one or more.

A User Equipment (UE) for performing uplink transmission in a specific cell, the terminal comprising:

• a communication module;
• and
• a processor configured to control the communication module,
• wherein the processor is configured to:
• transmit a transmission including a physical uplink shared channel (PUSCH)(s),
• receive a hybrid automatic repeat request acknowledgment (HARQ-ACK) feedback(s) corresponding to the PUSCH(s), and
• adjust a contention window size based on the HARQ-ACK feedback(s),
• wherein each of the PUSCH(s) is based on a Transport Block (TB) or a Code Block Group (CBG),
• wherein the HARQ-ACK feedback(s) includes at least one of a first HARQ-ACK feedback for a PUSCH based on the CBG or a second HARQ-ACK feedback for a PUSCH based on the TB,
• wherein each bit of the second HARQ-ACK feedback corresponds to each TB,
• wherein N bit(s) of the first HARQ-ACK feedback correspond to CBGs included in a TB,
• wherein the N is a maximum number of CBGs for the TB configured in the UE,
• wherein the contention window size is increased or reset to a minimum value according to whether one of a first condition for the first HARQ-ACK feedback and a second condition for the second HARQ-ACK feedback is satisfied,
• wherein the first condition is whether a ratio of bits indicating ACK in the first HARQ-ACK feedback is equal to or greater than a specific ratio, and
• wherein the second condition is whether a number of bits indicating ACK in the second HARQ-ACK feedback is one or more.