Method and apparatus for transmitting power headroom report by terminal in wireless communication system

1. A method for transmitting a power headroom report (PHR) by a user equipment performing wireless communication based on dual connectivity, the method comprising:

triggering the PHR based on at least one of a path loss change or a periodic timer; and

transmitting at least one PHR to a first base station and a second base station according to the dual connectivity,

wherein the at least one PHR comprises both a first power headroom (PH) for a first frequency band that is a serving frequency of the first base station and a second PH for a second frequency band that is the serving frequency of the second base station, when the user equipment simultaneously receives downlink signals from the first base station and the second base station and simultaneously transmits an uplink signal, and

wherein the transmitting of the at least one PHR comprises transmitting the at least one PHR for a first frequency band to the second base station when the at least one PHR for the second base station is triggered based on the user equipment receiving the downlink signals from one base station of the first base station and the second base station at a time and transmitting an uplink signal to only the corresponding base station at a time.

2. The method of claim 1 , wherein the at least one PHR comprises an

indicator indicating whether the at least one PHR comprises a PHR for a primary serving cell or an indicator indicating whether the PH is based on actual transmission or a reference format.

3. The method of claim 1 , wherein:

when one timer is configured in the user equipment, a PHR for the first base station and a PHR for the second base station are simultaneously transmitted, and

when one timer is configured in each of the first base station and the second base station, the PHR for the first base station and the PHR for the second base station are transmitted at different times.

4. The method of claim 1 , wherein:

the user equipment receives downlink signals from one base station of the first base station and the second base station at a time and transmits an uplink signal to only the one corresponding base station at a time,

when the PHR for the second base station is triggered and all triggered PHRs are transmitted, the PHR for a first frequency band is transmitted.

5. The method of claim 1 , wherein when each of the first base station and the second base station performs uplink scheduling, the PHR for a first frequency band is configured only in cells in the first base station and the PHR for a second frequency band is configured only in cells in the second base station.

6. The method of claim 1 , wherein different timers are configured in the first base station and the second base station.

7. A method for transmitting a power headroom report (PHR) by a user equipment performing wireless communication based on dual connectivity, the method comprising:

triggering the PHR based on at least one of a path loss change or a periodic timer; and

transmitting at least one PHR to a first base station and a second base station according to the dual connectivity,

wherein the at least one PHR comprises both a first power headroom (PH) for a first frequency band that is a serving frequency of the first base station and a second PH for a second frequency band that is the serving frequency of the second base station, when the user equipment simultaneously receives downlink signals from the first base station and the second base station and simultaneously transmits an uplink signal,

wherein the user equipment receives downlink signals from one base station of the first base station and the second base station at a time and transmits an uplink signal to only the one corresponding base station at a time, and wherein when the PHR for the second base station is triggered and all triggered PHRs are transmitted, the PHR for a first frequency band is transmitted.

8. The method of claim 7 , wherein the transmitting of the at least one PHR

comprises transmitting the at least one PHR comprising a first PH to the first base station and the at least one PHR comprising a second PH to the second base station when an uplink radio connection of the user equipment is configured with the first base station and the second base station, and the user equipment simultaneously receives downlink signals but transmits an uplink signal to only one base station at a time.

9. The method of claim 7 , wherein the transmitting of the at least one PHR comprises transmitting the at least one PHR for a first frequency band to the second base station when the at least one PHR for the second base station is triggered based on the user equipment receiving the downlink signals from one base station of the first base station and the second base station at a time and transmitting an uplink signal to only the corresponding base station at a time.

10. The method of claim 7 , wherein the at least one PHR comprises an

indicator indicating whether the at least one PHR comprises a PHR for a primary serving cell or an indicator indicating whether the PH is based on actual transmission or a reference format.

11. The method of claim 7 , wherein:

when one timer is configured in the user equipment, a PHR for the first base station and a PHR for the second base station are simultaneously transmitted, and

when one timer is configured in each of the first base station and the second base station, the PHR for the first base station and the PHR for the second base station are transmitted at different times.

12. The method of claim 7 , wherein when each of the first base station and the second base station performs uplink scheduling, the PHR for a first frequency band is configured only in cells in the first base station and the PHR for a second frequency band is configured only in cells in the second base station.

13. The method of claim 7 , wherein different timers are configured in the first base station and the second base station.