Method for controlling uplink transmission power and wireless device using same

1. A method for controlling an uplink transmit power in a wireless communication system, the method comprising:

receiving, by a wireless device, a configuration regarding first and second timing advance (TA) groups from a base station;

determining, by the wireless device, an uplink transmit power by considering an overlapping duration between subframes for a first serving cell belonging to the first TA group and a second serving cell belonging to the second TA group; and

transmitting, by the wireless device, an uplink channel based on the uplink transmit power.

2. The method of claim 1 , wherein the overlapping duration comprises:

a first overlapping duration in which a portion of a subframe n of the first serving cell overlaps with a subframe n of the second serving cell; and

a second overlapping duration in which the remaining portions of the subframe n of the first serving cell overlaps with a subframe n−1 or subframe n+1 of the second serving cell.

3. The method of claim 2 , wherein the determining of the uplink transmit power comprises:

determining a first power parameter in the first overlapping duration;

determining a second power parameter in the second overlapping duration;

selecting one of the first and second power parameters; and

determining the uplink transmit power on the basis of the selected power parameter.

4. The method of claim 3 , wherein the first power parameter includes a first maximum power reduction (MPR), and the second power parameter includes a second MPR.

5. The method of claim 4 , wherein a greater value is selected between the first MPR and the second MPR.

6. The method of claim 3 , wherein the first power parameter includes a first maximum transmit power, and the second power parameter includes a second maximum transmit power.

7. The method of claim 6 , wherein a smaller value is selected between the first maximum transmit power and the second maximum transmit power.

8. The method of claim 3 , wherein a power parameter corresponding to a greater overlapping duration is selected between the first and second power parameters.

9. The method of claim 2 , wherein the first serving cell is a primary cell.

10. A wireless device for controlling an uplink transmit power in a wireless communication system, the wireless device comprising:

a radio frequency (RF) unit configured to transmit and receive a radio signal; and

a processor operatively coupled to the RF unit and configured to:

instruct the RF unit to receive a configuration regarding first and second timing advance (TA) groups from a base station;

determine an uplink transmit power by considering an overlapping duration between subframes for a first serving cell belonging to the first TA group and a second serving cell belonging to the second TA group; and

instruct the RF unit to transmit an uplink channel based on the uplink transmit power.

11. The wireless device of claim 10 , wherein the overlapping duration comprises:

a first overlapping duration in which a portion of a subframe n of the first serving cell overlaps with a subframe n of the second serving cell; and

a second overlapping duration in which the remaining portions of the subframe n of the first serving cell overlaps with a subframe n−1 or subframe n+1 of the second serving cell.

12. The wireless device of claim 11 , wherein the processor determines the uplink transmit power by performing the operations of:

determining a first power parameter in the first overlapping duration;

determining a second power parameter in the second overlapping duration;

selecting one of the first and second power parameters; and

determining the uplink transmit power on the basis of the selected power parameter.