Semi-persistent channel state information reporting

1. A method of wireless communication performed by a user equipment (UE), comprising:

transmitting, to a base station via an uplink control channel, a negative acknowledgement (NACK) when a downlink shared channel transmission is not successfully received at the UE;

receiving, from the base station and based at least in part on the NACK, one or more channel state information reference signals (CSI-RSs) at one or more semi-persistent CSI measurement occasions; and

transmitting, to the base station, one or more CSI reports at one or more semi-persistent CSI reporting occasions corresponding to the one or more semi-persistent CSI measurement occasions, wherein the one or more CSI reports include one or more channel measurements based at least in part on the one or more CSI-RSs.

2. The method of claim 1 , further comprising:

receiving, from the base station, a medium access control (MAC) control element (CE) that activates a plurality of semi-persistent CSI occasions including:

the one or more semi-persistent CSI measurement occasions; and

the one or more semi-persistent CSI reporting occasions corresponding to the one or more semi-persistent CSI measurement occasions.

3. The method of claim 2 , further comprising:

receiving, from the base station, a parameter that defines a quantity associated with the plurality of semi-persistent CSI occasions.

4. The method of claim 1 , wherein the NACK is included in a plurality of NACKs transmitted over the uplink control channel, and a number associated with the plurality of NACKs satisfies a threshold.

5. The method of claim 1 , wherein the NACK is associated with NACK bits, and a percentage of bits transmitted over the uplink control channel corresponding to NACK bits satisfies a threshold.

6. The method of claim 1 , wherein the NACK and the one or more semi-persistent CSI measurement occasions associated with the one or more CSI-RSs are separated by a quantity of symbols based at least in part on a processing time of the base station.

7. The method of claim 1 , further comprising:

receiving, from the base station, a data transmission or a data retransmission based at least in part on the one or more CSI reports, wherein the data transmission or the data retransmission is associated with one or more of an adjusted modulation and coding scheme, an adjusted precoding matrix indicator, or an adjusted rank indicator based at least in part on the one or more CSI reports.

8. A method of wireless communication performed by a base station, comprising:

receiving, from a user equipment (UE) via an uplink control channel, a negative acknowledgement (NACK) when a downlink shared channel transmission is not successfully received at the UE;

transmitting, to the UE and based at least in part on the NACK, one or more channel state information reference signals (CSI-RSs) at one or more semi-persistent CSI measurement occasions; and

receiving, from the UE, one or more CSI reports at one or more semi-persistent CSI reporting occasions corresponding to the one or more semi-persistent CSI measurement occasions, wherein the one or more CSI reports includes one or more channel measurements based at least in part on the one or more CSI-RSs.

9. The method of claim 8 , further comprising:

transmitting, to the UE, a medium access control (MAC) control element (CE) that activates a plurality of semi-persistent CSI occasions including:

the one or more semi-persistent CSI measurement occasions; and

the one or more semi-persistent CSI reporting occasions corresponding to the one or more semi-persistent CSI measurement occasions.

10. The method of claim 9 , further comprising:

transmitting, to the UE, a parameter that defines a quantity associated with the plurality of semi-persistent CSI occasions.

11. The method of claim 8 , wherein the NACK is included in a plurality of NACKs transmitted over the uplink control channel, and a number associated with the plurality of NACKs satisfies a threshold.

12. The method of claim 8 , wherein the NACK is associated with NACK bits, and a percentage of bits transmitted over the uplink control channel corresponding to NACK bits satisfies a threshold.

13. The method of claim 8 , wherein the NACK and the one or more semi-persistent CSI measurement occasions associated with the one or more CSI-RSs are separated by a quantity of symbols based at least in part on a processing time of the base station.

14. The method of claim 8 , further comprising:

modifying, based at least in part on the one or more CSI reports, one or more of a modulation and coding scheme (MCS), a precoding matrix indicator (PMI), or a rank indicator (RI).

15. The method of claim 14 , further comprising:

performing, with the UE, a data transmission or a data retransmission based at least in part on one or more of the MCS, the PMI, or the RI.

16. A user equipment (UE) for wireless communication, comprising:

a memory; and

one or more processors coupled to the memory, wherein the one or more processors are configured to:

transmit, to a base station via an uplink control channel, a negative acknowledgement (NACK) when a downlink shared channel transmission is not successfully received at the UE;

receive, from the base station and based at least in part on the NACK, one or more channel state information reference signals (CSI-RSs) at one or more semi-persistent CSI measurement occasions; and

transmit, to the base station, one or more CSI reports at one or more semi-persistent CSI reporting occasions corresponding to the one or more semi-persistent CSI measurement occasions, wherein the one or more CSI reports include one or more channel measurements based at least in part on the one or more CSI-RSs.

17. The UE of claim 16 , wherein the one or more processors are further configured to:

receive, from the base station, a medium access control (MAC) control element (CE) that activates a plurality of semi-persistent CSI occasions including:

the one or more semi-persistent CSI measurement occasions; and

the one or more semi-persistent CSI reporting occasions corresponding to the one or more semi-persistent CSI measurement occasions.

18. The UE of claim 17 , wherein the one or more processors are further configured to:

receive, from the base station, a parameter that defines a quantity associated with the plurality of semi-persistent CSI occasions.

19. The UE of claim 16 , wherein the NACK is included in a plurality of NACKs transmitted over the uplink control channel, and a number associated with the plurality of NACKs satisfies a threshold.

20. The UE of claim 16 , wherein the NACK is associated with NACK bits, and a percentage of bits transmitted over the uplink control channel corresponding to NACK bits satisfies a threshold.

21. The UE of claim 16 , wherein the NACK and the one or more semi-persistent CSI measurement occasions associated with the one or more CSI-RSs are separated by a quantity of symbols based at least in part on a processing time of the base station.

22. The UE of claim 16 , wherein the one or more processors are further configured to:

receive, from the base station, a data transmission or a data retransmission based at least in part on the one or more CSI reports, wherein the data transmission or the data retransmission is associated with one or more of an adjusted modulation and coding scheme, an adjusted precoding matrix indicator, or an adjusted rank indicator based at least in part on the one or more CSI reports.

23. A base station for wireless communication, comprising:

a memory; and

one or more processors coupled to the memory, wherein the one or more processors are configured to:

receive, from a user equipment (UE) via an uplink control channel, a negative acknowledgement (NACK) when a downlink shared channel transmission is not successfully received at the UE;

transmit, to the UE and based at least in part on the NACK, one or more channel state information reference signals (CSI-RSs) at one or more semi-persistent CSI measurement occasions; and

receive, from the UE, one or more CSI reports at one or more semi-persistent CSI reporting occasions corresponding to the one or more semi-persistent CSI measurement occasions, wherein the one or more CSI reports includes one or more channel measurements based at least in part on the one or more CSI-RSs.

24. The base station of claim 23 , wherein the one or more processors are further configured to:

transmit, to the UE, a medium access control (MAC) control element (CE) that activates a plurality of semi-persistent CSI occasions including:

the one or more semi-persistent CSI measurement occasions; and

the one or more semi-persistent CSI reporting occasions corresponding to the one or more semi-persistent CSI measurement occasions.

25. The base station of claim 24 , wherein the one or more processors are further configured to:

transmit, to the UE, a parameter that defines a quantity associated with the plurality of semi-persistent CSI occasions.

26. The base station of claim 23 , wherein the NACK is included in a plurality of NACKs transmitted over the uplink control channel, and a number associated with the plurality of NACKs satisfies a threshold.

27. The base station of claim 23 , wherein the NACK is associated with NACK bits, and a percentage of bits transmitted over the uplink control channel corresponding to NACK bits satisfies a threshold.

28. The base station of claim 23 , wherein the NACK and the one or more semi-persistent CSI measurement occasions associated with the one or more CSI-RSs are separated by a quantity of symbols based at least in part on a processing time of the base station.

29. The base station of claim 23 , wherein the one or more processors are further configured to:

modify, based at least in part on the one or more CSI reports, one or more of a modulation and coding scheme (MCS), a precoding matrix indicator (PMI), or a rank indicator (RI).

30. The base station of claim 29 , wherein the one or more processors are further configured to:

perform, with the UE, a data transmission or a data retransmission based at least in part on one or more of the MCS, the PMI, or the RI.