Signaling design for non-PMI based CSI feedback

1. A method for wireless communication by a base station (BS), comprising:

determining, for each rank, one or more precoders available to a user equipment (UE) for reporting feedback to the BS;

generating a precoder configuration having a differential structure, wherein the differential structure of the precoder configuration implicitly indicates, from a plurality of ports, one or more ports associated with one of the precoders for each rank; and

signaling the precoder configuration with the differential structure to the UE.

2. The method of claim 1 , further comprising:

generating an interference measurement configuration indicating whether the UE is to use a remaining one or more ports, from the plurality of ports, for measuring interference from the BS; and

signaling the interference measurement configuration to the UE.

3. The method of claim 2 , further comprising:

generating a rank configuration indicating a rank selected from one or more available ranks; and

signaling the rank configuration to the UE.

4. The method of claim 3 , wherein the precoder configuration implicitly indicates one or more ports associated with one of the precoders for the selected rank indicated by the rank configuration.

5. The method of claim 3 , wherein generating the precoder configuration comprises generating the precoder configuration based in part on the rank configuration.

6. The method of claim 3 , wherein:

generating the precoder configuration, generating the rank configuration and generating the interference measurement configuration comprises generating a joint configuration of at least two of the precoder configuration, rank configuration or interference measurement configuration having a plurality of bits; and

signaling the joint configuration to the UE.

7. The method of claim 6 , wherein at least one of the rank configuration, the precoder configuration, the interference measurement configuration or the joint configuration is separately encoded.

8. The method of claim 3 , wherein at least one of the interference measurement configuration, precoder configuration or the rank configuration is semi-statically configured.

9. The method of claim 8 , wherein:

after the semi-static configuration, the at least one of the semi-statically configured precoder configuration, interference measurement configuration or rank configuration is overridden by at least one of a dynamically configured precoder configuration, interference measurement configuration or rank configuration.

10. The method of claim 3 , wherein at least one of the interference measurement configuration, precoder configuration or the rank configuration is dynamically configured.

11. The method of claim 10 , wherein:

the rank configuration is dynamically configured via a first stage of downlink control information (DCI); and

the precoder configuration is dynamically configured via a second stage of DCI.

12. The method of claim 3 , wherein the interference measurement configuration is encoded separately from at least one of the precoder configuration or rank configuration.

13. The method of claim 1 , wherein:

the precoder configuration comprises one or more bits;

a first set of the one or more bits indicates a first set of the ports associated with a first precoder for a first rank; and

at least the first set of the one or more bits and a second set of the one or more bits indicate at least a second set of ports associated with at least a second precoder for at least a second rank.

14. The method of claim 13 , wherein the second rank is greater than the first rank.

15. The method of claim 1 , wherein:

the precoder configuration comprises a plurality of bits indicating an ordering of the one or more ports;

a first port of the ordered one or more ports indicates the first port is associated with a first precoder for a first rank; and

the first port of the ordered one or more ports and at least a second port of the ordered one or more ports indicate the first port and at least the second port are associated with at least a second precoder for at least a second rank.

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

receiving a precoder configuration having a differential structure from a base station (BS);

determining, for each rank, one or more ports, from a plurality of ports, associated with one of a plurality of precoders available for reporting feedback to the BS, based on the differential structure of the precoder configuration; and

reporting feedback to the BS based on the determined one or more ports associated with one of the precoders.

17. The method of claim 16 , further comprising:

receiving from the BS an interference measurement configuration comprising an indication of whether the UE is to use a remaining one or more ports, from the plurality of ports, for measuring interference from the BS; and

determining whether to perform an interference measurement using the remaining one or more ports, based on the interference measurement configuration.

18. The method of claim 17 , further comprising receiving a rank configuration indicating a selected rank from one or more available ranks.

19. The method of claim 18 , wherein the one or more ports associated with the one or more ports are determined for the selected rank indicated from the rank configuration.

20. The method of claim 18 , wherein a format of the precoder configuration is based in part on the rank configuration.

21. The method of claim 18 , wherein:

receiving the precoder configuration, the interference measurement configuration and the rank configuration comprises receiving a joint configuration of at least two of the precoder configuration, rank configuration or interference measurement configuration; and

the joint configuration comprises a plurality of bits.

22. The method of claim 18 , wherein at least one of the interference measurement configuration, precoder configuration or the rank configuration is semi-statically configured.

23. The method of claim 22 , wherein:

after receiving the semi-static configuration, the at least one of the semi-statically configured precoder configuration, interference measurement configuration or rank configuration is overridden by at least one of a dynamically configured precoder configuration, interference measurement configuration or rank configuration.

24. The method of claim 18 , wherein at least one of the interference measurement configuration, precoder configuration or the rank configuration is dynamically configured.

25. The method of claim 24 , wherein:

the rank configuration is dynamically configured via first stage of downlink control information (DCI); and

the precoder configuration is dynamically configured via a second stage of DCI.

26. The method of claim 16 , wherein:

the precoder configuration comprises one or more bits; and

the determining comprises:

determining a first set of the one or more bits indicates a first set of the ports associated with a first precoder for a first rank; and

determining at least the first set of the one or more bits and a second set of the one or more bits indicate at least a second set of ports associated with at least a second precoder for at least a second rank.

27. The method of claim 26 , wherein the second rank is greater than the first rank.

28. The method of claim 16 , wherein:

the precoder configuration comprises a plurality of bits indicating an ordering of the one or more ports; and

the determining comprises:

determining a first port of the ordered one or more ports indicates the first port is associated with a first precoder for a first rank; and

determining the first port of the ordered one or more ports and at least a second port of the ordered one or more ports indicate the first port and at least the second port are associated with at least a second precoder for at least a second rank.

29. An apparatus comprising:

at least one processor configured to:

determine, for each rank, one or more precoders available to a user equipment (UE) for reporting feedback to the apparatus;

generate a precoder configuration having a differential structure, wherein the differential structure of the precoder configuration implicitly indicates, from a plurality of ports, one or more ports associated with one of the precoders for each rank; and

signal the precoder configuration with the differential structure to the UE; and

a memory coupled to the at least one processor.

30. An apparatus comprising:

at least one processor configured to:

receive a precoder configuration having a differential structure from a base station (BS);

determine, for each rank, one or more ports, from a plurality of ports, associated with one of a plurality of precoders available for reporting feedback to the BS, based on the differential structure of the precoder configuration; and

report feedback to the BS based on the determined one or more ports associated with one of the precoders; and

a memory coupled to the at least one processor.