Efficient and robust acknowledgement procedures for new radio operation in unlicensed bands
Systems, methods, and devices for efficient and robust handling of acknowledgements in new radio unlicensed bands (NR-U) environments. A wireless transmit receive unit (WTRU) may receive control information and a data transmission from a gNB in a first interval (i.e., transport block or channel occupancy time), wherein the control information may include an indication of uplink resources. The data transmission may require some sort of acknowledgement (i.e., HARQ feedback). The WTRU may attempt to transmit the acknowledgement in the indicated uplink resources, but the gNB may not receive the acknowledgement. The WTRU may receive control information and a data transmission from the gNB in a second interval, including an indication to aggregate any previously unsuccessful acknowledgement transmissions. The WTRU may transmit an aggregated acknowledgement including previous unsuccessful acknowledgements and any additional acknowledgements from the current interval. In some cases, look-before-talk procedures may be used.
1. A method implemented by a wireless transmit receive unit (WTRU), the method comprising:
receiving radio resource control (RRC) information regarding parameters for performing Type 2 Hybrid Automatic Repeat Request (HARQ) feedback;
receiving, while operating in New Radio Unlicensed (NR-U), first control information for a first physical downlink shared channel (PDSCH) transmission in a first physical downlink control channel (PDCCH) transmission, wherein the first control information includes a first HARQ feedback timing indicator;
determining not to send hybrid automatic repeat request (HARQ) feedback for the first PDSCH transmission based on a value of the first HARQ feedback timing indicator and the RRC information;
receiving second control information for a second PDSCH transmission in a second PDCCH transmission;
sending a first physical uplink control channel (PUCCH) transmission that includes HARQ feedback for the second PDSCH transmission based on the second control information and the RRC information;
receiving third control information for a third PDSCH transmission in a third PDCCH transmission, wherein the third control information includes an index indicating a PDSCH group, wherein the third control information includes downlink assignment information; and
sending, in a NR-U channel, a second PUCCH transmission that includes aggregated HARQ feedback based on the third control information and the RRC information, wherein the HARQ feedback for the first PDSCH transmission is aggregated with a HARQ feedback for the third PDSCH transmission to create the aggregated HARQ feedback based on the index indicating the PDSCH group, the downlink assignment information, and the RRC information.
2. The method of claim 1 , wherein the second control information includes a second HARQ feedback timing indicator used to send the first second PUCCH transmission.
3. The method of claim 1 , wherein the HARQ feedback for the third PDSCH transmission is sent based on timing indicated by a third HARQ feedback timing indicator.
4. The method of claim 1 , wherein the HARQ feedback for the third PDSCH transmission is sent on a Physical Uplink Control Channel (PUCCH) resource determined from the third control information.
5. The method of claim 1 , wherein the first HARQ feedback timing indicator is a first PDSCH-to-HARQ timing indicator.
6. The method of claim 1 , further comprising performing a listen-before-talk (LBT) prior to sending the first PUCCH transmission or the second PUCCH transmission.
7. The method of claim 1 , wherein the value of the first HARQ feedback timing indicator is outside of a current channel occupancy time (COT).
8. A wireless transmit receive unit (WTRU), the WTRU comprising:
a processor operatively coupled to a transceiver;
the transceiver configured to receive radio resource control (RRC) information regarding parameters for performing Type 2 Hybrid Automatic Repeat Request (HARQ) feedback;
the processor configured to receive, while operating in New Radio Unlicensed (NR-U), first control information for a first physical downlink shared channel (PDSCH) transmission in a first physical downlink control channel (PDCCH) transmission, wherein the first control information further includes a first HARQ feedback timing indicator;
the processor configured to determine not to send hybrid automatic repeat request (HARQ) feedback for the first PDSCH transmission based on a value of the first HARQ feedback timing indicator and the RRC information;
the transceiver configured to receive second control information for a second PDSCH transmission in a second PDCCH transmission;
sending a first physical uplink control channel (PUCCH) transmission that includes HARQ feedback for the second PDSCH transmission based on the second control information and the RRC information;
the transceiver configured to receive third control information for a third PDSCH transmission in a third PDCCH transmission, wherein the third control information includes an index indicating a PDSCH group, wherein the third control information includes downlink assignment information; and
the transceiver configured to send a second PUCCH transmission that includes aggregated HARQ feedback based on the third control information, wherein the HARQ feedback for the first PDSCH transmission is aggregated with a HARQ feedback for the third PDSCH transmission to create the aggregated HARQ feedback based on the index indicating the PDSCH group, the downlink assignment information, and the RRC information.
9. The WTRU of claim 8 , wherein the second control information includes a second HARQ feedback timing indicator used to send the first PUCCH transmission.
10. The WTRU of claim 8 , where the HARQ feedback for the third PDSCH transmission is sent based on timing indicated by a third HARQ feedback timing indicator.
11. The WTRU of claim 8 , wherein the HARQ feedback for the third PDSCH transmission is sent on a Physical Uplink Control Channel (PUCCH) resource determined from the third control information.
12. The WTRU of claim 8 , wherein the first HARQ feedback timing indicator is a first PDSCH-to-HARQ timing indicator.
13. The WTRU of claim 8 , the processor and transceiver configured to perform a listen-before-talk (LBT) prior to sending the first PUCCH transmission or the second PUCCH transmission.
14. The WTRU of claim 8 , wherein the value of the first HARQ feedback timing indicator is outside of a current channel occupancy time (COT).
15. A method implemented by a wireless transmit receive unit (WTRU), the method comprising:
receiving radio resource control (RRC) information regarding parameters for performing Type 2 Hybrid Automatic Repeat Request (HARQ) feedback;
receiving first control information for a first physical downlink shared channel (PDSCH) transmission in a first physical downlink control channel (PDCCH) transmission, wherein the first control information further includes a first HARQ feedback timing indicator, wherein the value of the first HARQ feedback timing indicator is outside of a current channel occupancy time (COT);
determining not to send a first hybrid automatic repeat request (HARQ) feedback for the first PDSCH transmission based on a value of the first HARQ feedback timing indicator and the RRC information;
receiving second control information for a second PDSCH transmission in a second PDCCH transmission, wherein the second control information includes an an index indicating a PDSCH group, wherein the second control information includes downlink assignment information; and
sending a physical uplink control channel (PUCCH) transmission that includes aggregated HARQ feedback based on the second control information, wherein the first HARQ feedback for the first PDSCH transmission is aggregated with a HARQ feedback for the second PDSCH transmission to create the aggregated HARQ feedback based on the index indicating the PDSCH group and the RRC information.
16. A wireless transmit receive unit (WTRU) comprising:
a processor operatively coupled to a transceiver;
the transceiver and processor configured to receive radio resource control (RRC) information regarding parameters for performing Type 2 Hybrid Automatic Repeat Request (HARQ) feedback;
the transceiver and processor configured to receive first control information for a first physical downlink shared channel (PDSCH) transmission in a first physical downlink control channel (PDCCH) transmission, wherein the first control information further includes a first HARQ feedback timing indicator, wherein the value of the first HARQ feedback timing indicator is outside of a current channel occupancy time (COT);
the transceiver and processor configured to determine not to send a first hybrid automatic repeat request (HARQ) feedback for the first PDSCH transmission based on a value of the first HARQ feedback timing indicator and the RRC information;
the transceiver and processor configured to receive second control information for a second PDSCH transmission in a second PDCCH transmission, wherein the second control information includes an indication of an index indicating a PDSCH group, wherein the second control information includes downlink assignment information; and
the transceiver and processor configured to send a physical uplink control channel (PUCCH) transmission that includes aggregated HARQ feedback based on the second control information, wherein the first HARQ feedback for the first PDSCH transmission is aggregated with a HARQ feedback for the second PDSCH transmission to create the aggregated HARQ feedback based on the index indicating the PDSCH group, the downlink assignment information, and the RRC information.