Method and apparatus for improving hybrid automatic repeat request (HARQ) feedback performance of enhanced mobile broadband (eMBB) when impacted by low latency traffic

A wireless transmit/receive unit (WTRU) comprising:

• a transceiver;
• and
• a processor, the processor configured to:
• receive, via the transceiver, configuration information indicating a maximum number of code block groups (CBGs) for CBG-based hybrid automatic repeat request (HARQ) feedback;
• receive, via the transceiver, an initial physical downlink shared channel transmission, the initial physical downlink shared channel transmission comprising a plurality of CBGs;
• determine that at least a first CBG of the plurality of CBGs comprised in the initial physical downlink shared channel transmission was successfully received, that at least a second CBG of the plurality of CBGs was not successfully received, and that at least a third CBG of the plurality of CBGs was not successfully received;
• transmit, via the transceiver, first HARQ feedback, the first HARQ feedback comprising a HARQ acknowledgment (HARQ-ACK) bit for the first CBG, a HARQ negative acknowledgment (HARQ-NACK) bit for the second CBG, and a HARQ-NACK bit for the third CBG;
• receive, via the transceiver, a retransmission that comprises the second CBG of the plurality of CBGs, wherein the first CBG is not comprised in the retransmission;
• determine that at least the second CBG was successfully received;
• determine that the third CBG was not included in the re-transmission;
• and
• transmit, via the transceiver, second HARQ feedback in response to the retransmission, wherein the second HARQ feedback transmitted in response to the retransmission comprises a HARQ-ACK bit for the first CBG that was not comprised in the retransmission, a HARQ-ACK bit for the second CBG that was comprised in the retransmission, and a HARQ-NACK bit for the third CBG.

A base station comprising:

• a transceiver;
• and
• a processor, the processor configured to:
• send, via the transceiver, configuration information indicating a maximum number of code block groups (CBGs) for CBG-based hybrid automatic repeat request (HARQ) feedback;
• send, via the transceiver, an initial physical downlink shared channel transmission, the initial physical downlink shared channel transmission comprising a plurality of CBGs;
• receive, via the transceiver, first HARQ feedback, the first HARQ feedback comprising a HARQ acknowledgment (HARQ-ACK) bit for the first CBG, a HARQ negative acknowledgment (HARQ-NACK) bit for the second CBG, and a HARQ-NACK bit for a third CBG;
• send, via the transceiver, a retransmission that comprises the second CBG of the plurality of CBGs, wherein the first CBG is not comprised in the retransmission;
• and
• receive, via the transceiver, second HARQ feedback in response to the retransmission, wherein the second HARQ feedback received in response to the retransmission comprises a HARQ-ACK bit for the first CBG that was not comprised in the retransmission, a HARQ-ACK bit for the second CBG that was comprised in the retransmission, and a HARQ-NACK bit for the third CBG.

A method performed by a base station, the method comprising:

• sending configuration information indicating a maximum number of code block groups (CBGs) for CBG-based hybrid automatic repeat request (HARQ) feedback;
• sending an initial physical downlink shared channel transmission, the initial physical downlink shared channel transmission comprising a plurality of CBGs;
• receiving first HARQ feedback, the first HARQ feedback comprising a HARQ acknowledgment (HARQ-ACK) bit for the first CBG, a HARQ negative acknowledgment (HARQ-NACK) bit for the second CBG, and a HARQ-NACK bit for the third CBG;
• sending a retransmission that comprises the second CBG of the plurality of CBGs, wherein the first CBG is not comprised in the retransmission;
• and
• receiving second HARQ feedback in response to the retransmission, wherein the second HARQ feedback received in response to the retransmission comprises a HARQ-ACK bit for the first CBG that was not comprised in the retransmission, a HARQ-ACK bit for the second CBG that was comprised in the retransmission, and a HARQ-NACK bit for the third CBG.