A method and an apparatus in a mobile communication system are provided. The method by a terminal in a mobile communication system includes receiving first information for activating a secondary cell (SCell) from a base station, activating the SCell based on the first information, starting a timer associated with the SCell, restarting, if second information for the activated SCell is received from the base station, the timer associated with the SCell, and if the timer expires, applying by the terminal, one or more corresponding actions for deactivating the SCell no later than in a predefined subframe. The one or more corresponding actions include at least one of preventing from transmitting a sounding reference signal (SRS) on the SCell, and preventing from reporting at least one of a channel quality indicator (CQI), a precoding matrix index (PMI), a rank indicator (RI), and a precoder type indicator (PTI) for the SCell

An improved method and an apparatus for reporting Power Headroom (PH) of a UE are provided. The Power Headroom Report (PHR) method of the present invention includes determining whether to trigger PHR based on a change of Power Management Maximum Power Reduction (P-MPR) between two time points, generating, if PHR is determined to be triggered, Power Headroom, and reporting the Power Headroom information to a base station.

A method and an apparatus for efficiently transmitting or reporting a Power Headroom Report (PHR) of a User Equipment (UE) are provided. The method of transmitting the PHR of the UE in a mobile communication system includes configuring an extended PHR including an indicator corresponding to a variation factor of a maximum transmission power of the UE, and transmitting the extended PHR from the UE to a Base Station (BS). The BS may be notified of a maximum transmission power of the UE and a variation factor corresponding to the maximum transmission power in order to enable efficient scheduling.

A method and an apparatus in a mobile communication system are provided. The method includes receiving, by the terminal, first information for activating a secondary Cell (SCell) from a base station, activating, by the terminal, the SCell based on the first information, starting, by the terminal, a timer associated with the SCell, restarting, by the terminal, if second information for the activated SCell is received from the base station, the timer associated with the SCell, and, if the timer expires, applying by the terminal, one or more corresponding actions for deactivating the SCell no later than in a predefined subframe, wherein the second information includes at least one of an uplink grant on the activated SCell, a downlink assignment on the activated SCell, and a control message for activating the SCell.

A method and an apparatus for deactivating secondary carriers in a mobile communication system using carrier aggregation are provided. A communication method, for a User Equipment (UE), includes activating a secondary carrier, starting a first timer upon activation of the secondary carrier, starting a second timer when the first timer expires, and deactivating the activated secondary carrier when the second timer expires.

A method and an apparatus in a mobile communication system are provided. The method by a terminal in the mobile communication system includes receiving, by the terminal, first information for activating a secondary cell (SCell) from a base station, activating, by the terminal, the SCell based on the first information, starting, by the terminal, a timer associated with the SCell, restarting, by the terminal, if second information for the activated SCell is received from the base station, the timer associated with the SCell, and if the timer expires, applying by the terminal, one or more corresponding actions for deactivating the SCell no later than in a predefined subframe. The one or more corresponding actions include at least one of preventing, by the terminal, from monitoring a physical downlink control channel (PDCCH) on the SCell and preventing, by the terminal, from monitoring a PDCCH for the SCell.

A method and an apparatus in a mobile communication system are provided. The method by a terminal in the mobile communication system includes receiving, by the terminal, first information for activating a secondary cell (SCell) from a base station, activating, by the terminal, the SCell based on the first information, starting, by the terminal, a timer associated with the SCell, restarting, by the terminal, if second information for the activated SCell is received from the base station, the timer associated with the SCell, and if the timer expires, applying by the terminal, one or more corresponding actions for deactivating the SCell no later than in a predefined subframe. The first information includes a bitmap indicator corresponding to at least one SCell.

A method and an apparatus for efficiently transmitting or reporting a Power Headroom Report (PHR) of a User Equipment (UE) are provided. The method of transmitting the PHR of the UE in a mobile communication system includes configuring an extended PHR including an indicator corresponding to a variation factor of a maximum transmission power of the UE, and transmitting the extended PHR from the UE to a Base Station (BS). The BS may be notified of a maximum transmission power of the UE and a variation factor corresponding to the maximum transmission power in order to enable efficient scheduling.

A method and an apparatus for efficiently transmitting or reporting a Power Headroom Report (PHR) of a User Equipment (UE) are provided. The method of transmitting the PHR of the UE in a mobile communication system includes configuring an extended PHR including an indicator corresponding to a variation factor of a maximum transmission power of the UE, and transmitting the extended PHR from the UE to a Base Station (BS). The BS may be notified of a maximum transmission power of the UE and a variation factor corresponding to the maximum transmission power in order to enable efficient scheduling.

A method and an apparatus for efficiently transmitting or reporting a Power Headroom Report (PHR) of a User Equipment (UE) are provided. The method of transmitting the PHR of the UE in a mobile communication system includes configuring an extended PHR including an indicator corresponding to a variation factor of a maximum transmission power of the UE, and transmitting the extended PHR from the UE to a Base Station (BS). The BS may be notified of a maximum transmission power of the UE and a variation factor corresponding to the maximum transmission power in order to enable efficient scheduling.