Method and apparatus for pathloss derivation for beam operation in a wireless communication system
A method and apparatus are disclosed, from the perspective of the UE, for deriving UE transmit power. In one embodiment, the method includes the UE deriving a first pathloss value measured from a first reference signal. In addition, the method includes the UE deriving a second pathloss value measured from a second reference signal. The method also includes the UE transmitting a first UL transmission wherein the UL transmit power of the first UL transmission is derived from the first pathloss value. The method further includes the UE transmitting a second UL transmission wherein the UL transmit power of the second UL transmission is derived from the second pathloss value.
1. A method of deriving UE transmit power for UL (Uplink) transmission to a Transmission/Reception Point (TRP), comprising:
a UE derives a first pathloss value measured from a first reference signal;
the UE derives a second pathloss value measured from a second reference signal;
the UE transmits a first UL transmission to the TRP wherein a UL transmit power of the first UL transmission is derived from the first pathloss value; and
the UE transmits a second UL transmission to the same TRP wherein a UL transmit power of the second UL transmission is derived from the second pathloss value; and
wherein the first reference signal and the second reference signal are different types of reference signals.
2. The method of claim 1 , wherein the first UL transmission and the second UL transmission are different types of UL transmission.
3. The method of claim 2 , wherein the type of the first UL transmission is associated with at least the first reference signal for pathloss derivation, and the type of the second UL transmission is associated with at least the second reference signal for pathloss derivation.
4. The method of claim 3 , wherein the association between the type of UL transmission and reference signal is specified or configured or indicated via signalling.
5. The method of claim 1 , wherein the first reference signal is at least one of a reference signal for beam tracking/beam finding, a reference signal for control demodulation, a reference signal for data demodulation, a reference signal for channel measurement, or a reference signal for pathloss, and/or the second reference signal is at least one of a reference signal for beam tracking/beam finding, a reference signal for control demodulation, a reference signal for data demodulation, a reference signal for channel measurement, or a reference signal for pathloss.
6. The method of claim 5 , wherein the reference signal for beam tracking/beam finding is a beam reference signal.
7. The method of claim 1 , wherein the pathloss value for deriving UL transmit power of the associated type of UL transmission is selected among multiple beams, and the selected pathloss value is the smallest pathloss value among the multiple beams.
8. The method of claim 5 , wherein the reference signal for control demodulation is DMRS (Demodulation Reference Signal) for control.
9. The method of claim 8 , wherein the pathloss value derived from the reference signal for control demodulation is valid for the UL transmission associated with the received control signalling.
10. The method of claim 5 , wherein the reference signal for data demodulation is DMRS (Demodulation Reference Signal) for data.
11. The method of claim 10 , wherein the pathloss value derived from the reference signal for data demodulation is valid for the UL transmission associated with the received DL (Downlink) data transmission.
12. The method of claim 5 , the type of UL transmission associated with the reference signal for data demodulation comprises: HARQ-ACK (Hybrid Automatic Repeat Request-Acknowledgement), an aperiodic CSI, a periodic CSI, and/or an UL data transmission.
13. The method of claim 5 , wherein the reference signal for channel measurement is CSI-RS (Channel State Information-Reference Signal).
14. The method of claim 1 , wherein if UL transmit power of a UL data transmission is derived from the pathloss value derived from one associated CSI-RS (Channel State Information-Reference Signal) resource/process, the associated CSI-RS resource/process is indicated in control signaling which schedules the UL data transmission.
15. The method of claim 1 , wherein if a type of UL transmission is associated with different reference signals, one reference signal of the different reference signals is determined for the pathloss value utilized for determining UL transmit power of the UL transmission.
16. The method of claim 15 , wherein the pathloss value of the latest associated reference signal is utilized for determining the UL transmit power of the UL transmission.
17. The method of claim 5 , wherein the valid pathloss value derived from the reference signal for data or control demodulation or the reference signal for channel measurement is utilized for determining the UL transmit power of first some types of UL transmission, instead of the valid pathloss value derived from the reference signal for beam tracking/beam finding.
18. The method of claim 5 , wherein the type of UL transmission associated with the reference signal for beam tracking/beam finding comprises: UL data transmission, SRS (Sounding Reference Signal), UL control, HARQ-ACK (Hybrid Automatic Repeat Request-Acknowledgement), CSI (Channel State Information) report, SR (Scheduling Request), and/or preamble.
19. The method of claim 5 , wherein the type of UL transmission associated with the reference signal for channel measurement comprises: an aperiodic CSI (Channel State Information), a periodic CSI, and/or an UL data transmission.
20. The method of claim 1 , wherein the first UL transmission and the second UL transmission are transmitted on different beams, and
wherein the first path loss value and the second path value are derived based on the different beams respectively.
21. The method of claim 1 , wherein the first reference signal is a reference signal for channel measurement, and the first UL transmission is a first UL data transmission,
and wherein the second reference signal is a reference signal for beam tracking or beam finding, and the second UL transmission is a second UL data transmission.
22. The method of claim 1 , wherein the first reference signal is a reference signal for channel measurement, and the first UL transmission is UL data transmission,
and wherein the second reference signal is a reference signal for beam tracking or beam finding, and the second UL transmission is any of preamble, SRS, UL control, HARQ-ACK, CSI report, SR.
23. The method of claim 1 , wherein the first reference signal is a reference signal for channel measurement, and the first UL transmission is UL data transmission,
and wherein the second reference signal is a reference signal for data demodulation, and the second UL transmission is any of HARQ-ACK for DL data transmission, an aperiodic CSI, a periodic CSI.
24. A UE (User Equipment) for deriving transmit power for UL(Uplink) transmission to a Transmission/Reception Point (TRP), comprising:
a control circuit;
a processor installed in the control circuit; and
a memory installed in the control circuit and operatively coupled to the processor, wherein the processor is configured to execute a program code stored in the memory to perform operations comprising:
deriving a first pathloss value measured from a first reference signal;
deriving a second pathloss value measured from a second reference signal;
transmitting a first UL transmission to the TRP wherein a UL transmit power of the first UL transmission is derived from the first pathloss value; and
transmitting a second UL transmission to the same TRP wherein a UL transmit power of the second UL transmission is derived from the second pathloss value; and
wherein the first reference signal and the second reference signal are different types of reference signals.