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

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.

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.