Power headroom reporting method and device for wireless communication system

1. A method for reporting a power headroom (PH) of a user equipment (UE) in a wireless communication system supporting carrier aggregation, the method comprising the steps of:

receiving a configuration message to configure an uplink carrier;

receiving a control message to activate the uplink carrier;

determining whether a predetermined time has elapsed after receiving the control message; and

triggering a power headroom report (PHR), prior to receiving an uplink grant, if the predetermined time has elapsed,

wherein the received uplink grant is associated with the uplink carrier.

2. The method of claim 1 , further comprising:

determining whether the uplink grant is received when the PHR is triggered; and

if the uplink grant is received, calculating the PH of the PHR, generating the PHR using the calculated PH, and transmitting the generated PHR.

3. The method of claim 2 , further comprising:

if the uplink grant is not received, continuing to await an allowance of a resource for uplink transmission until the receipt of the uplink grant.

4. The method of claim 1 , further comprising:

transmitting the PHR on a resource indicated by the uplink grant.

5. A user equipment (UE) device in a wireless communication system supporting carrier aggregation, the UE comprising:

a transceiver for receiving a configuration message to configure an uplink carrier, and receiving a control message to activate the uplink carrier; and

a controller for determining whether a predetermined time has elapsed after receiving the control message, and triggering a power headroom report (PHR), prior to receiving an uplink grant, if the predetermined time has elapsed,

wherein the received uplink grant is associated with the uplink carrier.

6. The device of claim 5 , wherein the controller determines whether the uplink grant is received when the PHR is triggered, and if the uplink grant is received, controls the PH calculator to calculate the PH of the PHR, generates the PHR using the calculated PH, and controls the transceiver to transmit the generated PHR.

7. The device of claim 6 , wherein, if the uplink grant is not received, the controller continues to await an allowance of a resource for uplink transmission until the receipt of the uplink grant.

8. The device of claim 5 , wherein the controller controls to transmit the PHR on a resource indicated by the uplink grant.

9. A method for processing a power headroom (PH) of a base station in a wireless communication system supporting carrier aggregation, the method comprising the steps of:

transmitting a configuration message to a user equipment (UE) to configure an uplink carrier;

transmitting a control message to the UE for activating the uplink carrier; and

receiving a power headroom report (PHR) from the UE after a predetermined time period has elapsed,

wherein the PHR is triggered at the UE prior to reception of an uplink grant and after the predetermined time period has elapsed, and

wherein the uplink grant is associated with the uplink carrier.

10. The method of claim 9 , wherein, if the uplink grant is received when the PHR is triggered, the PH is calculated and the PHR is generated based on the calculated PH.

11. The method of claim 10 , wherein, if the uplink grant is not received when the PHR is triggered, the calculation of the PH and the generation of the PHR are not performed until the uplink grant is received.

12. The method of claim 9 , wherein the PHR is received on a resource indicated by the uplink grant.

13. A base station in a wireless communication system supporting carrier aggregation, the base station comprising:

a transceiver for transmitting and receiving a signal; and

a controller for transmitting a configuration message to a user equipment (UE) to configure an uplink carrier, for transmitting a control message to the UE for activating the uplink carrier, and receiving a power headroom report (PHR) from the UE after a predetermined time period has elapsed,

wherein the PHR is triggered at the UE prior to reception of an uplink grant and after the predetermined time period has elapsed, and

wherein the uplink grant is associated with the uplink carrier.

14. The base station of claim 13 , wherein if the uplink grant is received when the PHR is triggered, the PH is calculated and the PHR is generated based on the calculated PH.

15. The base station of claim 14 , wherein if the uplink grant is not received when the PHR is triggered, the calculation of PH and the generation of the PHR are not performed until the uplink grant is received.

16. The base station of claim 13 , wherein the controller controls to receive the PHR on a resource indicated by the uplink grant.