Method and apparatus for event-based uplink transmit beam switch

1. A user equipment (UE) comprising:

a transceiver configured to:

receive configuration information including information on a beam indication indicating N uplink (UL) transmit beams, where N>1, and

receive the beam indication; and

a processor operably coupled to the transceiver, the processor configured to:

determine whether an event is detected,

select a beam from the N UL transmit beams based on whether the event is detected or not,

in response to the event not being detected, select a first beam from the N UL transmit beams as the beam, and

in response to the event being detected, select a second beam from the N UL transmit beams as the beam, and

wherein the transceiver is further configured to transmit an UL transmission using the selected beam, and

wherein each beam from the N UL transmit beams refers to a spatial property used to receive or transmit a source reference signal (RS).

2. The UE of claim 1 , wherein the event detection is based on whether a maximum permissible exposure (MPE) limit is met or not.

3. The UE of claim 1 , wherein:

the UE is equipped with at least first and second antenna panels, and

the processor is further configured to determine that the event is detected based on a determination to switch from the first antenna panel to the second antenna panel.

4. The UE of claim 1 , wherein the beam is selected based on a priority order among the N UL transmit beams.

5. The UE of claim 1 , wherein:

the transceiver is configured to receive configuration information including information about measurement RS resources and information about a beam reporting,

the processor is configured to measure the measurement RS resources and calculate the beam reporting based on the measured measurement RS resources,

the transceiver is further configured to transmit the beam reporting,

the measurement RS resources comprise channel state information reference signals (CSI-RSs) or synchronization signal blocks (SSBs) or both CSI-RSs and SSBs,

the beam reporting includes at least one resource indicator and a beam metric associated with the at least one resource indicator, and

the beam indication is based on the beam reporting.

6. The UE of claim 1 , wherein the beam indication is via a transmission configuration indicator (TCI) state including at least one source RS.

7. The UE of claim 1 , wherein the beam indication is via N transmission configuration indicator (TCI) states, one TCI state for each of the N UL transmit beams, and each TCI state includes at least one source RS.

8. The UE of claim 1 , wherein:

the beam indication is via first and second transmission configuration indicator (TCI) states, TCI 1 and TCI 2 , respectively, each of the first and second TCI states including at least one source RS, and

the processor is configured to:

use the TCI 1 to determine one of the N UL transmit beams, and

use the TCI 2 to determine remaining N−1 of the N UL transmit beams.

9. A base station (BS) comprising:

a processor configured to:

generate configuration information including information on a beam indication indicating N uplink (UL) transmit beams, where N>1, and

generate the beam indication; and

a transceiver operably coupled to the processor, the transceiver configured to:

transmit the configuration information,

transmit the beam indication, and

receive an UL transmission transmitted using a beam from the N UL transmit beams, wherein the beam is selected based on whether an event is detected,

wherein if the event is not detected, the beam is a first beam from the N UL transmit beams,

wherein if the event is detected, the beam is a second beam from the N UL transmit beams, and

wherein each beam from the N UL transmit beams refers to a spatial property used to receive or transmit a source reference signal (RS).

10. The BS of claim 9 , wherein the event detection is based on whether a maximum permissible exposure (MPE) limit is met or not.

11. The BS of claim 9 , wherein the beam is selected based on a priority order among the N UL transmit beams.

12. The BS of claim 9 , wherein:

the transceiver is configured to:

transmit configuration information including information about measurement RS resources and information about a beam reporting,

transmit the measurement RS resources, and

receive the beam reporting,

the measurement RS resources comprises channel state information reference signal (CSI-RSs) or synchronization signal blocks (SSBs) or both CSI-RSs and SSBs,

the beam reporting includes at least one resource indicator and a beam metric associated with the at least one resource indicator, and

the beam indication is based on the beam reporting.

13. The BS of claim 9 , wherein the beam indication is via a transmission configuration indicator (TCI) state including at least one source RS.

14. The BS of claim 9 , wherein the beam indication is via N transmission configuration indicator (TCI) states, one TCI state for each of the N UL transmit beams, and each TCI state includes at least one source RS.

15. The BS of claim 9 , wherein:

the beam indication is via first and second transmission configuration indicator (TCI) states, TCI 1 and TCI 2 , respectively, each of the first and second TCI states including at least one source RS,

the TCI 1 indicates one of the N UL transmit beams, and

the TCI 2 indicates remaining N−1 of the N UL transmit beams.

16. A method for operating a user equipment (UE), the method comprising:

receiving configuration information including information on a beam indication indicating N uplink (UL) transmit beams, where N>1;

receiving the beam indication;

determining whether an event is detected;

selecting a beam from the N UL transmit beams based on whether the event is detected or not;

in response to the event not being detected, selecting the beam to be a first beam from the N UL transmit beams; and

in response to the event being detected, selecting the beam to be a second beam from the N UL transmit beams; and

transmitting an UL transmission using the selected beam,

wherein each beam from the N UL transmit beams refers to a spatial property used to receive or transmit a source reference signal (RS).

17. The method of claim 16 , wherein the beam indication is via a transmission configuration indicator (TCI) state including at least one source RS.

18. The method of claim 16 , wherein the beam indication is via first and second transmission configuration indicator (TCI) states, TCI 1 and TCI 2 , respectively, each of the first and second TCI states including at least one source RS, the method further comprising:

using the TCI 1 to determine one of the N UL transmit beams, and

using the TCI 2 to determine remaining N−1 of the N UL transmit beams.

19. The method of claim 16 , further comprising selecting the beam based on a priority order among the N UL transmit beams.

20. The method of claim 16 , further comprising:

receiving configuration information including information about measurement RS resources and information about a beam reporting;

measuring the measurement RS resources and calculating the beam reporting based on the measured measurement RS resources; and

transmitting the beam reporting,

wherein:

the measurement RS resources comprise channel state information reference signals (CSI-RSs) or synchronization signal blocks (SSBs) or both CSI-RSs and SSBs,

the beam reporting includes at least one resource indicator and a beam metric associated with the at least one resource indicator, and

the beam indication is based on the beam reporting.