Hybrid reconfiguration methods and apparatus for TDD adaptation
Methods, systems, and devices are described for reconfiguring a user equipment (UE) to operate in a reconfigured TDD UL-DL configuration. An initial uplink-downlink (UL-DL) configuration for TDD communication may be provided for communication between an e Node B and a UE. One or more subframes within each frame transmitted using the initial UL-DL configuration may be identified as flexible subframes. The identification of flexible subframes may permit the identification of timing for HARQ transmissions that does not change when a reconfiguration takes place. A different UL-DL configuration may be transmitted to the UE, in which at least one flexible subframe is to be changed from an uplink subframe to a downlink subframe. The different UL-DL configuration may be transmitted by, for example, a pseudo-uplink grant to the UE, which indicates that the UE is to reconfigure one or more flexible subframes from uplink to downlink transmission.
1. A method of wireless communication performed by a user equipment (UE) in time-division duplex (TDD) communication with an eNodeB, comprising:
receiving an initial uplink-downlink (UL-DL) configuration for TDD communication with the eNodeB;
identifying one or more subframes within the initial UL-DL configuration as flexible subframes;
receiving an uplink grant comprising an indication that at least one of the one or more flexible subframes of a given frame is to be changed from an uplink subframe to a downlink subframe, wherein the indication comprises an invalid resource block allocation for the at least one of the one or more flexible subframes of the given frame; and
receiving downlink communications during one or more of the flexible subframes changed from an uplink subframe to a downlink subframe.
2. The method of claim 1 , wherein receiving the uplink grant comprises receiving physical layer signaling at the UE.
3. The method of claim 1 , wherein the invalid resource block allocation comprises a resource indication value (RIV) that exceeds a maximum value of an RIV for the uplink grant.
4. The method of claim 1 , further comprising:
receiving a second uplink grant comprising an indication that a second of the one or more flexible subframes of the given frame is to be changed from an uplink subframe to a downlink subframe.
5. The method of claim 1 , wherein HARQ acknowledgment timing is unchanged between the initial UL-DL configuration and a reconfigured UL-DL configuration.
6. The method of claim 1 , wherein the initial UL-DL configuration comprises a maximum number of uplink subframes within each frame.
7. The method of claim 6 , further comprising:
determining an uplink HARQ acknowledgment position within a set of subframes based on an UL-DL configuration of the maximum number of uplink subframes.
8. The method of claim 6 , wherein the maximum number of uplink subframes is received in a system information block (SIB).
9. The method of claim 6 , wherein the initial UL-DL configuration further comprises a minimum number of uplink subframes within each frame.
10. The method of claim 9 , further comprising:
determining a downlink HARQ acknowledgment position within a set of subframes based on an UL-DL configuration of the minimum number of uplink subframes.
11. The method of claim 9 , wherein the minimum number of uplink subframes are received using a bitmap identifying the minimum number of uplink subframes.
12. The method of claim 9 , wherein the minimum number of uplink subframes are transmitted using a configuration index that identifies minimum uplink subframes in a semi-static set of different minimum uplink subframes.
13. The method of claim 1 , further comprising:
receiving the initial UL-DL configuration from the eNodeB.
14. The method of claim 13 , wherein the initial UL-DL configuration is received in one system information block (SIB).
15. The method of claim 1 , wherein the flexible subframes are initially configured as uplink subframes.
16. A wireless communication user equipment (UE) apparatus configured to operate using one of multiple time-division duplex (TDD) uplink-downlink (UL-DL) configurations, comprising:
at least one processor configured to:
receive an initial uplink-downlink (UL-DL) configuration for TDD communication with an eNodeB;
identify one or more subframes within the initial UL-DL configuration as flexible subframes;
receive an uplink grant comprising an indication that at least one of the one or more flexible subframes of a given frame is to be changed from an uplink subframe to a downlink subframe, wherein the indication comprises an invalid resource block allocation for the at least one of the one or more flexible subframes of the given frame; and
receive downlink communications during one or more of the flexible subframes changed from an uplink subframe to a downlink subframe; and
a memory coupled with the at least one processor.
17. The apparatus of claim 16 , wherein the at least one processor is configured to receive the uplink grant via physical layer signaling received at the UE.
18. The apparatus of claim 16 , wherein the invalid resource block allocation comprises a resource indication value (RIV) that exceeds a maximum value of an RIV for the uplink grant.
19. The apparatus of claim 16 , wherein the initial UL-DL configuration is received in a system information block (SIB).
20. A wireless communication user equipment (UE) apparatus configured to operate using one of multiple time-division duplex (TDD) uplink-downlink (UL-DL) configurations, comprising:
means for receiving an initial uplink-downlink (UL-DL) configuration for TDD communication with an eNodeB;
means for identifying one or more subframes within the initial UL-DL configuration as flexible subframes;
means for receiving an uplink grant comprising an indication that at least one of the one or more flexible subframes of a given frame is to be changed from an uplink subframe to a downlink subframe, wherein the indication comprises an invalid resource block allocation for the at least one of the one or more flexible subframes of the given frame; and
means for receiving downlink communications during one or more of the flexible subframes changed from an uplink subframe to a downlink subframe.
21. The apparatus of claim 20 , wherein the means for receiving the uplink grant comprises means for receiving physical layer signaling.
22. A method of wireless communication performed by a user equipment (UE) in time-division duplex (TDD) communication with an eNodeB, comprising:
receiving an initial uplink-downlink (UL-DL) configuration for TDD communication with the eNodeB;
receiving an uplink grant comprising an indication to reconfigure the initial UL-DL configuration to a different UL-DL configuration for a given frame, wherein the indication comprises an invalid resource block allocation for at least one flexible subframe of the initial UL-DL configuration for the given frame; and
communicating with the eNodeB according to the different UL-DL configuration for the given frame.
23. The method of claim 22 , wherein the invalid resource block allocation comprises a resource indication value (RIV) that exceeds a maximum value of an RIV for the uplink grant.
24. The method of claim 22 , wherein the uplink grant comprises an indication to reconfigure the initial UL-DL configuration for a first flexible subframe of the given frame, and wherein the method further comprises receiving a second uplink grant comprising an indication to reconfigure the initial UL-DL configuration for a second flexible subframe of the given frame.
25. The method of claim 1 , further comprising:
detecting whether a downlink grant is present in one or more of the flexible subframes changed from an uplink subframe to a downlink subframe.
26. The method of claim 1 , further comprising:
suppressing detection of downlink grants during flexible subframes that are not changed from an uplink subframe to a downlink subframe.