Methods and apparatus for employing multiple subframe configurations for HARQ operations

1. A method for wireless communications by a user equipment (UE), comprising:

identifying a first reference subframe configuration to use as a reference for hybrid automatic repeat request (HARQ) operations for transmissions on an uplink;

identifying a second reference subframe configuration to use as a reference for HARQ operations for transmissions on a downlink;

determining transmission of at least one of a periodic channel state information feedback and a periodic scheduling request based on the second reference subframe configuration; and

communicating with at least a node on the uplink and the downlink based on the first and second reference subframe configurations,

wherein at least the first reference subframe configuration for transmissions on the uplink is received via broadcast signaling including a System Information Block (SIB) Type 1.

2. The method of claim 1 , further comprising identifying a current subframe configuration for sending transmissions on the uplink and receiving transmissions on the downlink, wherein the current subframe configuration is different from at least one of the first or second reference subframe configurations.

3. The method of claim 1 , wherein the second reference subframe configuration for transmissions on the downlink is identified from at least two reference subframe configurations.

4. The method of claim 3 , wherein the at least two reference subframe configurations comprise at least one of time division duplex (TDD) Uplink/Downlink (UL/DL) subframe configuration #2 and TDD UL/DL subframe configuration #5, or TDD UL/DL subframe configuration of a 5 ms switching periodicity and TDD UL/DL subframe configuration of a 10 ms switching periodicity.

5. The method of claim 1 , further comprising:

interpreting an information field in a downlink control information (DCI) format for scheduling on the uplink based on the second reference subframe configuration, wherein the information field comprises an uplink index field; and

wherein for at least one second reference subframe configuration, interpreting an information field in a DCI format for scheduling on the uplink based on the second reference subframe configuration includes interpreting the uplink index field as at least one of a downlink assignment field indicating a total number of downlink assignments or an uplink index field indicating one or more uplink subframes to be scheduled.

6. The method of claim 1 , wherein at least the second reference subframe configuration for transmissions on the downlink is received semi-statically via radio resource control (RRC) signaling.

7. The method of claim 1 , further comprising:

determining at least one of a number of HARQ processes, a scheduling timing, or HARQ timing for the uplink based on the first reference subframe configuration; and

determining at least one of a number of HARQ processes or HARQ timing for the downlink based on the second reference subframe configuration.

8. The method of claim 1 , wherein HARQ operations include HARQ timing.

9. A method for wireless communications by a base station (BS), comprising:

identifying a first reference subframe configuration to use as a reference for hybrid automatic repeat request (HARQ) operations for transmissions on an uplink;

identifying a second reference subframe configuration to use as a reference for HARQ operations for transmissions on a downlink; and

communicating with at least one user equipment (UE) on the uplink and the downlink based on the first and second reference subframe configurations,

wherein at least the first reference subframe configuration for transmissions on the uplink is signaled via broadcast signaling including a System Information Block (SIB) Type 1, and

wherein transmission of at least one of a periodic channel state information feedback and a periodic scheduling request is determined based on the second reference subframe configuration.

10. The method of claim 9 , wherein the second reference subframe configuration for transmissions on the downlink is identified from at least one of time division duplex (TDD) Uplink/Downlink (UL/DL) subframe configuration of a 5 ms switching periodicity or TDD UL/DL subframe configuration of a 10 ms switching periodicity.

11. The method of claim 9 , further comprising:

providing information in an information field in a downlink control information (DCI) format for scheduling in the uplink, the information provided based on the second reference subframe configuration, wherein the information field comprises an uplink index field; and

wherein for at least one second reference subframe configuration, providing information in an information field in a DCI format for scheduling in the uplink includes providing, in an uplink index field, at least one of downlink assignment information indicating a total number of downlink assignments or information indicating one or more uplink subframes to be scheduled.

12. The method of claim 9 , wherein at least the second reference subframe configuration for transmissions on the downlink is semi-statically signaled via radio resource control (RRC) signaling.

13. The method of claim 9 , further comprising:

identifying another reference subframe configuration for at least one of the transmissions on the uplink or the transmissions on the downlink based on actual traffic or load of a network over which the BS communicates with the UE.

14. The method of claim 9 , wherein HARQ operations include HARQ timing.

15. An apparatus for wireless communications, comprising:

a processor configured to:

identify a first reference subframe configuration to use as a reference for hybrid automatic repeat request (HARQ) operations for transmissions on an uplink;

identify a second reference subframe configuration to use as a reference for HARQ operations for transmissions on a downlink;

determine transmission of at least one of a periodic channel state information feedback and a periodic scheduling request based on the second reference subframe configuration; and

communicate with at least a node on the uplink and the downlink based on the first and second reference subframe configurations,

wherein the processor is configured to receive at least the first reference subframe configuration for the uplink via broadcast signaling including System Information Block (SIB) Type 1; and

a memory coupled to the processor.

16. The apparatus of claim 15 , wherein the processor is further configured to identify a current subframe configuration for sending transmissions on the uplink and receiving transmissions on the downlink, wherein the current subframe configuration is different from at least one of the first or second reference subframe configurations.

17. The apparatus of claim 15 , wherein the second reference subframe configuration for transmissions on the downlink is identified from at least two reference subframe configurations and the at least two reference subframe configurations comprise time division duplex (TDD), Uplink/Downlink (UL/DL) subframe configuration of a 5 ms switching periodicity and TDD UL/DL subframe configuration of a 10 ms switching periodicity.

18. The apparatus of claim 15 , further comprising:

wherein the processor is further configured to interpret an information field in a downlink control information (DCI) format for scheduling on the uplink based on the second reference subframe configuration, wherein the information field comprises an uplink index field; and

wherein for at least one second reference subframe configuration, interpreting an information field in a DCI format for scheduling on the uplink based on the second reference subframe configuration includes interpreting the uplink index field as at least one of a downlink assignment field indicating a total number of downlink assignments or an uplink index field indicating one or more uplink subframes to be scheduled.

19. The apparatus of claim 15 , wherein the processor is further configured to receive at least the second reference subframe configuration for the downlink semi-statically via radio resource control (RRC) signaling.

20. The apparatus of claim 15 , the processor is further configured to:

determine at least one of a number of HARQ processes, a scheduling timing or HARQ timing for the uplink based on the first reference subframe configuration; and

determine at least one of a number of HARQ processes or HARQ timing for the downlink based on the second reference subframe configuration.

21. An apparatus for wireless communications, comprising:

a processor configured to:

identify a first reference subframe configuration to use as a reference for hybrid automatic repeat request (HARQ) operations for transmissions on an uplink;

identify a second reference subframe configuration to use as a reference for HARQ operations for transmissions on a downlink; and

communicate with at least one user equipment (UE) on the uplink and the downlink based on the first and second reference subframe configurations,

wherein the processor is further configured to signal at least the first reference subframe configuration for the uplink via broadcast signaling including System Information Block (SIB) Type 1, and

wherein transmission of at least one of a periodic channel state information feedback and a periodic scheduling request is determined based on the second reference subframe configuration; and

a memory coupled to the processor.

22. The apparatus of claim 21 , wherein the second reference subframe configuration for the downlink is identified from at least one of at least time division duplex (TDD) Uplink/Downlink (UL/DL) subframe configuration #2 or TDD UL/DL subframe configuration #5, or TDD UL/DL subframe configuration of a 5 ms switching periodicity or TDD UL/DL subframe configuration of a 10 ms switching periodicity.

23. The apparatus of claim 21 , wherein the processor is further configured to:

provide information in an information field in a downlink control information (DCI) format for scheduling in the uplink, the information provided based on the second reference subframe configuration, wherein the information field comprises an uplink index field; and

wherein for at least one second reference subframe configuration, providing information in an information field in a DCI format for scheduling in the uplink includes providing, in an uplink index field, at least one of downlink assignment information indicating a total number of downlink assignments or information indicating one or more uplink subframes to be scheduled.

24. The apparatus of claim 21 , wherein the processor is further configured to signal at least the second reference subframe configuration for the downlink semi-statically via Radio Resource Control (RRC) signaling.

25. The apparatus of claim 21 , wherein the processor is further configured to identify another reference subframe configuration for at least one of the uplink or the downlink based on actual traffic or load of a network over which the apparatus communicates with the UE.