Adaptive antenna management in LTE
Certain aspects of the present disclosure relate to methods and apparatus for adaptive antenna management in LTE. Devices and networks capable of transmitting and receiving signals using a variable number of transmitting or receiving antennas using LTE radio access technology are described.
1. A method for wireless communications by a user equipment (UE), comprising:
determining, by the UE, switch points for the UE to switch between different antenna configurations for at least one of uplink or downlink communications, wherein the determining comprises deriving the switch points based on timing of at least one of transmitting channel state information (CSI) feedback or transmitting uplink reference signals; and
adjusting, by the UE, parameters for transmitting at least one of the CSI feedback or the uplink reference signals based on the determination.
2. The method of claim 1 , wherein:
switch points for switching between downlink antenna configurations coincide with when the UE transmits CSI feedback.
3. The method of claim 1 , wherein:
switch points for switching between downlink antenna configurations coincide with when the UE transmits uplink reference signals.
4. The method of claim 1 , wherein determining the switch points comprises:
determining the switch points based on at least one of a defined periodicity or offset.
5. The method of claim 4 , further comprising:
selecting an antenna configuration to use after a switch point; and
providing an indication of the selected antenna configuration.
6. The method of claim 4 , further comprising:
receiving an indication of an antenna configuration to use after a switch point.
7. The method of claim 1 , further comprising:
providing CSI feedback for multiple antenna configurations.
8. The method of claim 7 , further comprising:
receiving an indication of an antenna configuration selected based, at least in part, on the CSI feedback provided for the multiple antenna configurations.
9. The method of claim 1 , wherein:
the UE is configured with a plurality of uplink antenna configurations based on a number of physical antennas available for uplink transmissions.
10. The method of claim 1 , further comprising:
transmitting uplink reference signals on selected uplink antenna configurations.
11. The method of claim 1 , wherein:
the UE is configured to utilize a downlink antenna configuration for processing downlink transmissions that corresponds to a most recent transmitted CSI feedback.
12. The method of claim 1 , further comprising:
determining a rank indication (RI) bitwidth based on a maximum supportable number of layers across an antenna configuration.
13. The method of claim 1 , further comprising:
determining a rank indication (RI) bitwidth separately for periodic and aperiodic feedback.
14. A method for wireless communications by a base station (BS), comprising:
determining, by the BS, switch points for a user equipment (UE) to switch between different antenna configurations for at least one of uplink or downlink communications, wherein the determining comprises deriving the switch points based on timing of at least one of the UE transmitting channel state information (CSI) feedback or the UE transmitting uplink reference signals; and
adjusting, by the BS, parameters used for processing at least one of the CSI feedback or the uplink reference signals based on the determination.
15. The method of claim 14 , wherein:
switch points for switching between downlink antenna configurations coincide with when the UE transmits CSI feedback.
16. The method of claim 14 , wherein:
switch points for switching between downlink antenna configurations coincide with when the UE transmits uplink reference signals.
17. The method of claim 14 , wherein determining the switch points comprises:
determining the switch points based on at least one of a defined periodicity or offset.
18. The method of claim 17 , further comprising:
selecting an antenna configuration to use after a switch point; and
signaling to the UE an indication of the selected antenna configuration.
19. The method of claim 17 , further comprising:
receiving an indication of an antenna configuration in use after a switch point.
20. The method of claim 14 , further comprising:
receiving CSI feedback for multiple antenna configurations.
21. The method of claim 20 , further comprising:
transmitting an indication of an antenna configuration selected based, at least in part, on the CSI feedback provided for the multiple antenna configurations.
22. The method of claim 14 , wherein:
the UE is configured with a plurality of uplink antenna configurations based on a number of physical antennas available for uplink transmissions.
23. The method of claim 14 , further comprising:
receiving uplink reference signals on selected uplink antenna configurations.
24. The method of claim 14 , wherein:
the UE is configured to utilize a downlink antenna configuration for processing downlink transmissions that corresponds to a most recent transmitted CSI feedback.
25. The method of claim 14 , further comprising:
determining a rank indication (RI) bitwidth based on a maximum supportable number of layers across an antenna configuration.
26. The method of claim 14 , further comprising:
determining a rank indication (RI) bitwidth separately for periodic and aperiodic feedback.
27. An apparatus for wireless communications by a user equipment (UE), comprising:
at least one processor configured to determine switch points for the UE to switch between different antenna configurations for at least one of uplink or downlink communications, wherein the determining comprises deriving the switch points based on timing of at least one of transmitting channel state information (CSI) feedback or transmitting uplink reference signals, and adjust parameters for transmitting at least one of the CSI feedback or the uplink reference signals based on the determination; and
a memory coupled with the at least one processor.
28. An apparatus for wireless communications by a base station (BS), comprising:
at least one processor configured to determine switch points for a user equipment (UE) to switch between different antenna configurations for at least one of uplink or downlink communications, wherein the determining comprises deriving the switch points based on timing of at least one of the UE transmitting channel state information (CSI) feedback or the UE transmitting uplink reference signals, and adjust parameters used for processing at least one of the CSI feedback or the uplink reference signals based on the determination; and
a memory coupled with the at least one processor.