Communication method using a carrier aggregation and apparatus therefore

A user equipment for use in a wireless communications system using multiple uplink component carriers, the user equipment comprising:

• a radio frequency (RF) unit configured to transmit and receive wireless signals to and from a base station;
• a memory configured to store information being transmitted and received to and from the base station and parameters used for performing operations of the user equipment;
• and
• a processor connected to the RF unit and the memory, and configured to control the RF unit and the memory, so as to operate the user equipment,
• wherein the processor is configured to:
• receive, from the base station, Radio Resource Control (RRC) configuration information for a Sounding Reference Signal (SRS), the configuration information including information for periodically transmitting the SRS to the base station, and
• perform a procedure for periodically transmitting the SRS on an uplink component carrier of the multiple uplink component carriers to the base station in use of the configuration information,
• wherein if the uplink component carrier is in an active state at a time for transmitting the SRS, a transmission of the SRS is performed at the time for transmitting the SRS,
• wherein if the uplink component carrier is in a non-active state at a time for transmitting the SRS, the transmission of the SRS is skipped at the time for transmitting the SRS,
• wherein the uplink component carrier is in the non-active state, when all downlink component carriers paired with the uplink component carrier are all in the non-active state, and
• wherein signal reception is normally performed by the user equipment on a downlink component carrier in the active state, and the signal reception is limited by the user equipment on a downlink component carrier in the non-active state.