A method and an apparatus are provided for transmitting a hybrid automatic repeat request-acknowledgment/negative acknowledgment (HARQ-ACK/NACK). A first set including at least one HARQ-ACK/NACK timing value is identified. Each timing value indicates a time difference between a downlink time unit for physical downlink shared channel (PDSCH) reception and an uplink time unit in which a HARQ-ACK/NACK feedback is transmitted. A second set is determined that includes at least one downlink time unit. A codebook is generated for the HARQ-ACK/NACK feedback. A size of the codebook is identified based on a size of the second set and a number of HARQ-ACK/NACK bits corresponding to each downlink time unit. The codebook is transmitted to the base station. The number of HARQ-ACK/NACK bits is determined based on a number of code block groups (CBGs) in one transmission block (TB), in case that scheduling for a downlink transmission is based on CBG.