Method and apparatus for HARQ-ACK codebook determination are disclosed. One method of UE includes receiving one or more downlink transmissions; determining a first set of HARQ-AC feedback timing values for generating a first HARQ-ACK codebook; performing a first Listen-Before-Talk (LBT) for transmitting the first HARQ-ACK codebook in a first transmission opportunity, wherein the first HARQ-ACK codebook includes the HARQ-ACK feedback corresponding to the one or more downlink transmissions; transmitting the first HARQ-ACK codebook in the first transmission opportunity in response to the first LBT being successful; and determining a second set of HARQ-ACK feedback timing values for generating a second HARQ-ACK codebook and performing a second LBT for transmitting the second HARQ-ACK codebook in a second transmission opportunity in response to the first LBT being unsuccessful, wherein the second HARQ-ACK codebook includes the HARQ-ACK feedback corresponding to the one or more downlink transmissions.