Codeword layer mapping for rate-splitting MIMO communication

1. An apparatus for wireless communication at a user equipment (UE), comprising:

a memory; and

at least one processor coupled to the memory and, based at least in part on information stored in the memory, the at least one processor is configured to:

receive a first indication of a mapping of a plurality of layers to a first common codeword (c-CW) and a first private codeword (p-CW) from a network entity, wherein the first indication indicates the first c-CW corresponds to at least one first layer of the plurality of layers and the first p-CW corresponds to at least one second layer of the plurality of layers, wherein the plurality of layers is associated with multiple input-multiple output (MIMO) communication, wherein the first c-CW and the first p-CW are associated with rate-splitting for the MIMO communication;

identify a first set of modulated symbols of the first c-CW that is mapped to the at least one first layer and a second set of modulated symbols of the first p-CW that is mapped to the at least one second layer based on the first indication; and

perform a decoding process for at least one of the first c-CW or the first p-CW based on at least one of the first set of modulated symbols or the second set of modulated symbols.

2. The apparatus of claim 1 , further comprising a transceiver coupled to the at least one processor, wherein to receive the first indication the at least one processor is configured to receive first downlink control information (DCI) comprising the first indication, wherein the at least one processor is configured to:

receive, via the transceiver, second DCI scheduling a MIMO communication without rate-splitting, wherein the second DCI has a same size as the first DCI, wherein the second DCI includes padding.

3. The apparatus of claim 1 , wherein the first indication comprises at least one of a second indication of a first number of layers of the at least one first layer of the plurality of layers mapped to the first c-CW, a third indication of a second number of layers of the at least one second layer of the plurality of layers mapped to the first p-CW, or a fourth indication of a set of demodulation reference signal (DMRS) ports associated with the first c-CW or the first p-CW.

4. The apparatus of claim 3 , wherein a number of modulated symbols per layer of the plurality of layers is fixed, wherein the at least one first layer of the plurality of layers mapped to the first c-CW is consecutive and the at least one second layer of the plurality of layers mapped to the first p-CW is consecutive, wherein the at least one processor is further configured to identify the first set of modulated symbols and the second set of modulated symbols further based on the first number of layers of the at least one first layer of the plurality of layers mapped to the first c-CW, the second number of layers of the at least one second layer of the plurality of layers mapped to the first p-CW, and the number of modulated symbols per layer of the plurality of layers.

5. The apparatus of claim 1 , wherein the first indication comprises a second indication of a total number of layers of the plurality of layers, wherein calculating the second number of layers or calculating the first number of layers is in response to the first indication indicating a presence of at least one c-CW, wherein the at least one processor is further configured to:

calculate a second number of layers of the at least one second layer of the plurality of layers mapped to the first p-CW based on a third indication of a first number of layers of the at least one first layer of the plurality of layers mapped to the first c-CW and the total number of layers of the plurality of layers, wherein the first indication comprises the third indication; or

calculate the first number of layers of the at least one first layer of the plurality of layers mapped to the first c-CW based on a fourth indication of the second number of layers of the at least one second layer of the plurality of layers mapped to the first p-CW and the total number of layers of the plurality of layers, wherein the first indication comprises the fourth indication.

6. The apparatus of claim 1 , wherein the first indication comprises a second indication of a total number of layers of the plurality of layers, wherein the at least one processor is further configured to:

calculate a second number of layers of the at least one second layer of the plurality of layers mapped to the first p-CW based on a first number of layers of the at least one first layer of the plurality of layers mapped to the first c-CW and the total number of layers of the plurality of layers, wherein the first number of layers of the at least one first layer of the plurality of layers is fixed.

7. The apparatus of claim 1 , wherein the first indication comprises a second number of layers of the at least one second layer of the plurality of layers mapped to the first p-CW, wherein a first number of layers of the at least one first layer of the plurality of layers mapped to the first c-CW is fixed.

8. The apparatus of claim 1 , wherein a number of modulated symbols per layer of the plurality of layers is fixed, wherein the at least one processor is further configured to identify the first set of modulated symbols and the second set of modulated symbols further based on the number of modulated symbols per layer of the plurality of layers.

9. The apparatus of claim 1 , wherein the at least one processor is further configured to:

transmit a capability indication of a first maximum number of layers for the first c-CW and a second maximum number of layers for the first p-CW, wherein the mapping of the plurality of layers is further based on the capability indication.

10. The apparatus of claim 1 , wherein the first c-CW is associated with a first decoding process for a plurality of UEs and the first p-CW is associated with a second decoding process for the first UE, wherein the at least one processor is further configured to perform the decoding process by decoding at least one of the first c-CW or the first p-CW based on at least one of the first set of modulated symbols or the second set of modulated symbols.

11. The apparatus of claim 1 , wherein the first indication further comprises at least one of a second indication of a first number of layers of the at least one first layer of the plurality of layers mapped to the first c-CW or a third indication of a second number of layers of at least one third layer of the plurality of layers mapped to a second c-CW.

12. The apparatus of claim 1 , wherein the at least one processor is further configured to:

calculate a first number of layers of the at least one first layer of the plurality of layers mapped to the first c-CW and a second number of layers of at least one third layer of the plurality of layers mapped to a second c-CW, wherein the first indication comprises a total number of layers of the plurality of layers associated with at least one of the first c-CW and the second c-CW.

13. The apparatus of claim 1 , wherein the first indication further comprises at least one of a second indication of a first number of layers of the at least one second layer of the plurality of layers mapped to the first p-CW or a third indication of a second number of layers of at least one third layer of the plurality of layers mapped to a second p-CW.

14. The apparatus of claim 1 , wherein the at least one processor is further configured to:

calculate a first number of layers of the at least one second layer of the plurality of layers mapped to the first p-CW and a second number of layers of at least one third layer of the plurality of layers mapped to a second p-CW, wherein the first indication comprises a total number of layers of the plurality of layers associated with at least one of the first p-CW and the second p-CW.

15. The apparatus of claim 1 , wherein the at least one processor is further configured to:

transmit feedback associated with at least one of channel state information (CSI) or a sounding reference symbols (SRS), wherein the mapping of the plurality of layers is further based on the transmitted feedback.

16. An apparatus for wireless communication at a network entity, comprising:

a memory; and

at least one processor coupled to the memory and, based at least in part on information stored in the memory, the at least one processor is configured to:

map a plurality of layers to a first common codeword (c-CW) and a first private codeword (p-CW), wherein a first set of modulated symbols of the first c-CW is mapped to at least one first layer of the plurality of layers and a second set of modulated symbols of the first p-CW is mapped to at least one second layer of the plurality of layers, wherein the plurality of layers is associated with multiple input-multiple output (MIMO) communication, wherein the first c-CW and the first p-CW are associated with rate-splitting for the MIMO communication; and

transmit a first indication of the mapping of the plurality of layers to the first c-CW and the first p-CW for a first user equipment (UE), wherein the first indication indicates that the first c-CW corresponds to the at least one first layer and the first p-CW corresponds to the at least one second layer.

17. The apparatus of claim 16 , further comprising a transceiver coupled to the at least one processor, wherein to transmit the first indication of the mapping the at least one processor is configured to transmit first downlink control information (DCI) comprising the first indication, wherein the at least one processor is further configured to:

transmit second DCI scheduling a MIMO communication without rate-splitting, wherein the second DCI has a same size as the first DCI, wherein the second DCI includes padding.

18. The apparatus of claim 16 , wherein the first indication comprises at least one of a second indication of a first number of layers of the at least one first layer of the plurality of layers mapped to the first c-CW or a third indication of a second number of layers of the at least one second layer of the plurality of layers mapped to the first p-CW, wherein the first indication comprises a fourth indication of a set of demodulation reference signal (DMRS) ports associated with the first c-CW or the first p-CW.

19. The apparatus of claim 16 , wherein the first indication comprises a second indication of a total number of layers of the plurality of layers, wherein the first indication comprises one of a third indication of a first number of layers of the at least one first layer of the plurality of layers mapped to the first c-CW or a fourth indication of a second number of layers of the at least one second layer of the plurality of layers mapped to the first p-CW.

20. The apparatus of claim 16 , wherein a first number of layers of the at least one first layer of the plurality of layers mapped to the first c-CW is fixed, wherein the first indication comprises a second indication of a second number of layers of the at least one second layer of the plurality of layers mapped to the first p-CW, wherein the first indication comprises a third indication of a total number of layers of the plurality of layers.

21. The apparatus of claim 16 , wherein a first number of layers of the at least one first layer of the plurality of layers mapped to the first c-CW is fixed, wherein the first indication comprises a second indication of a number of c-CWs scheduled for the MIMO communication associated with rate-splitting.

22. The apparatus of claim 16 , wherein a number of modulated symbols per layer of the plurality of layers is fixed, wherein the at least one first layer of the plurality of layers mapped to the first c-CW is consecutive and the at least one second layer of the plurality of layers mapped to the first p-CW is consecutive.

23. The apparatus of claim 16 , wherein the at least one processor is further configured to:

receive a capability indication of a first maximum number of layers for the first c-CW and a second maximum number of layers for the first p-CW, wherein the mapping of the plurality of layers is further based on the capability indication, wherein a rank indicator (RI) of the first c-CW does not exceed the first maximum number of layers for the first c-CW.

24. The apparatus of claim 16 , wherein the at least one processor is further configured to:

receive feedback associated with at least one of channel state information (CSI) or a sounding reference symbol (SRS) from the first UE, wherein the mapping of the plurality of layers is further based on the received feedback.

25. The apparatus of claim 16 , wherein the first c-CW is associated with a first decoding process for a plurality of UEs and the first p-CW is associated with a second decoding process for a first UE.

26. The apparatus of claim 16 , wherein the first indication further comprises at least one of a second indication of a first number of layers of the at least one first layer of the plurality of layers mapped to the first c-CW or a third indication of a second number of layers of at least one third layer of the plurality of layers mapped to a second c-CW.

27. The apparatus of claim 16 , wherein mapping the plurality of layers comprises mapping the plurality of layers to a second p-CW, wherein a third set of modulated symbols of the second p-CW is mapped to at least one third layer of the plurality of layers, wherein the at least one first layer of the plurality of layers mapped to the first p-CW is consecutive, wherein the at least one third layer of the plurality of layers mapped to the second p-CW is consecutive.

28. The apparatus of claim 16 , wherein the at least one processor is further configured to:

receive a capability indication of a maximum number of c-CWs or a maximum number of p-CWs, wherein the mapping of the plurality of layers is further based on the capability indication.

29. A method of wireless communication at a user equipment (UE), comprising:

receiving a first indication of a mapping of a plurality of layers to a first common codeword (c-CW) and a first private codeword (p-CW) from a network entity, wherein the first indication indicates the first c-CW corresponds to at least one first layer of the plurality of layers and the first p-CW corresponds to at least one second layer of the plurality of layers, wherein the plurality of layers is associated with multiple input-multiple output (MIMO) communication, wherein the first c-CW and the first p-CW are associated with rate-splitting for the MIMO communication;

identifying a first set of modulated symbols of the first c-CW that is mapped to the at least one first layer and a second set of modulated symbols of the first p-CW that is mapped to the at least one second layer based on the first indication; and

performing a decoding process for at least one of the first c-CW or the first p-CW based on at least one of the first set of modulated symbols or the second set of modulated symbols.

30. A method of wireless communication at a network entity, comprising:

mapping a plurality of layers to a first common codeword (c-CW) and a first private codeword (p-CW), wherein a first set of modulated symbols of the first c-CW is mapped to at least one first layer of the plurality of layers and a second set of modulated symbols of the first p-CW is mapped to at least one second layer of the plurality of layers, wherein the plurality of layers is associated with multiple input-multiple output (MIMO) communication, wherein the first c-CW and the first p-CW are associated with rate-splitting for the MIMO communication; and

transmitting a first indication of the mapping of the plurality of layers to the first c-CW and the first p-CW for a first user equipment (UE), wherein the first indication indicates that the first c-CW corresponds to the at least one first layer and the first p-CW corresponds to the at least one second layer.