Methods and apparatus for HARQ enhancement

A wireless transmit/receive unit (WTRU) for wireless communications, the WTRU comprising:

• a processor configured to determine, for each of a plurality of downlink (DL) transmissions, a respective codebook process from a set of codebook processes based on a first indication associated with a respective codebook process index, wherein each of the plurality of DL transmissions is associated with one or more hybrid automatic repeat request (HARQ) feedback bits;
• a receiver configured to receive, in downlink control information (DCI), a second indication to transmit a set of HARQ feedback bits using one or more uplink (UL) control resources, wherein the second indication comprises at least a codebook process index and a HARQ retransmission indicator;
• the processor further configured to determine one or more DL transmissions from the plurality of DL transmissions based on:
• 1) the respective codebook process determined for each respective DL transmission, 2) the received codebook process index, and 3) the received HARQ retransmission indicator;
• and
• a transmitter configured to transmit the set of HARQ feedback bits associated with the determined one or more DL transmissions using the one or more UL control resources.