Apparatus and method for performing uplink power control in wireless communication system supporting carrier aggregation

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

configuring, for a user equipment (UE), a primary serving cell on which a first uplink control channel is transmitted from the UE, the first uplink control channel comprising uplink control information of the primary serving cell;

configuring, for the UE, a secondary serving cell on which a second uplink control channel is transmitted from the UE, the second uplink control channel comprising uplink control information of the secondary serving cell;

configuring a first transmit power control (TPC) command and a second TPC command in a single TPC command group, the first TPC command being associated with transmit power of the uplink control information of the primary serving cell, the second TPC command being associated with transmit power of the uplink control information of the secondary serving cell;

scrambling downlink control information based on an identifier associated with a TPC, the downlink control information comprising the single TPC command group; and

transmitting, to the UE, the scrambled downlink control information,

wherein configuring of the first TPC command and the second TPC command in the single TPC command group comprises separately assigning an index for the first TPC command associated with a physical uplink control channel (PUCCH) on the primary serving cell and an index for the second TPC command associated with PUCCH on the secondary serving cell.

2. The method of claim 1 , further comprising mapping the downlink control information to a common search space of the primary serving cell,

wherein the downlink control information corresponds to physical downlink control channel (PDCCH), and the downlink control information is scrambled with a same TPC-PUCCH radio network temporary identifier (RNTI).

3. The method of claim 1 , wherein the index for the first TPC command associated with the primary serving cell configured for the UE is different from the index for the second TPC command associated with the secondary serving cell configured for the UE.

4. The method of claim 3 , further comprising:

transmitting, through a radio resource control (RRC) message, a TPC-physical downlink control channel (PDCCH)-config message to assign, for the UE, the index for the first TPC command and the index for the second TPC command,

wherein the downlink control information corresponds to a PDCCH associated with the TPC-PDCCH-config message.

5. The method of claim 3 , wherein the index for the first TPC command has different bit sizes, according to downlink control information format 3 or downlink control information format 3A, and

wherein the index for the second TPC command has different bit sizes, according to downlink control information format 3 or downlink control information format 3A.

6. The method of claim 1 , wherein the single TPC command group comprises a third TPC command for controlling transmit power of an uplink channel of another UE.

7. The method of claim 1 , further comprising:

establishing a connection with the UE through the primary serving cell; and

receiving a radio resource control (RRC) message through the primary serving cell.

8. The method of claim 1 , wherein:

a first piece of downlink control information comprising the single TPC command group is scrambled using a TPC physical uplink control channel (PUCCH) radio network temporary identifier (RNTI); and

a second piece of downlink control information different from the first piece of downlink control information is scrambled using another RNTI.

9. The method of claim 1 , wherein the first TPC command is associated with transmit power of the first uplink control channel,

wherein the first uplink control channel further comprises uplink control information of at least one secondary serving cell grouped, together with the primary serving cell, in a first serving cell group.

10. The method of claim 1 , wherein the second TPC command is associated with transmit power of the second uplink control channel,

wherein the second uplink control channel further comprises uplink control information of at least one secondary serving cell grouped, together with the secondary serving cell, in a second serving cell group.

11. A method for receiving a transmit power control (TPC) command in a wireless communication system supporting carrier aggregation (CA), the method comprising:

establishing a connection with a base station through a primary serving cell (PCell);

receiving, by a user equipment (UE), a radio resource control (RRC) message comprising a first transmit power control (TPC) index associated with a physical uplink control channel (PUCCH) transmission on the PCell and a second TPC index associated with a PUCCH transmission on a secondary serving cell (SCell), the SCell together with the PCell being configured as serving cells for the UE;

detecting a physical downlink control channel (PDCCH) by monitoring a common search space of the PCell,

wherein a downlink control information (DCI) format of the PDCCH comprises a first TPC command for controlling transmit power of the PUCCH transmission on the PCell and a second TPC command for controlling transmit power of the PUCCH transmission on the SCell;

identifying the first TPC command and the second TPC command from the DCI format based on the first TPC index and the second TPC index, respectively;

controlling transmit power of the PUCCH transmission on the PCell based on a value of the first TPC command, and controlling transmit power of the PUCCH transmission on the SCell based on a value of the second TPC command.

12. The method of claim 11 , further comprising:

configuring a CA for the UE using the PCell and a plurality of SCells; and

determining the PUCCH transmission on the SCell selected from among the plurality of SCells.

13. The method of claim 11 , wherein the RRC message is received through the PCell.

14. The method of claim 11 , wherein the DCI format corresponds to DCI format 3, and each of the first TPC index and the second TPC index corresponds to different 2-bit data of the DCI format 3.

15. The method of claim 11 , wherein the DCI format corresponds to DCI format 3A, and each of the first TPC index and the second TPC index corresponds to different 1-bit data of the DCI format 3A.

16. The method of claim 11 , wherein the DCI format comprises a third TPC command for controlling transmit power of the PUCCH transmission of another UE.

17. The method of claim 16 , further comprising identifying the first TPC command, the second TPC command, and the third TPC command from the PDCCH scrambled with one TPC PUCCH radio network temporary identifier (RNTI).

18. The method of claim 17 , wherein the RRC message further comprises information of the TPC PUCCH RNTI.

19. The method of claim 11 , further comprising determining first uplink control information (UCI) to be included in the PUCCH transmission on the PCell, and second UCI to be included in the PUCCH transmission on the SCell.

20. A base station to transmit a transmit power control (TPC) command in a wireless communication system supporting Carrier Aggregation (CA), the base station comprising:

a processor to establish a connection with a user equipment (UE) through a primary serving cell (PCell);

a radio frequency (RF) transmitter that cooperates with the processor for transmitting to the UE a Radio Resource Control (RRC) message comprising a first transmit power control (TPC) index associated with a physical uplink control channel (PUCCH) transmission on the PCell and a second TPC index associated with a PUCCH transmission on a secondary serving cell (SCell), the SCell together with the PCell being configured as serving cells for the UE,

wherein the RF transmitter transmits a physical downlink control channel (PDCCH) by cooperating with the processor to map the PDCCH to a common search space of the PCell,

wherein a downlink control information (DCI) format of the PDCCH comprises a first TPC command for controlling transmit power of the PUCCH transmission on the PCell and a second TPC command for controlling transmit power of the PUCCH transmission on the SCell, and

wherein the processor is configured to determine a value of the first TPC command to control transmit power of the PUCCH transmission on the PCell and to determine a value of the second TPC command to control transmit power of the PUCCH transmission on the SCell, the value of the first TPC command being mapped in the DCI format based on the first TPC index and the value of the second TPC command being mapped in the DCI format based on the second TPC index.