Method and apparatus for managing multiple timing advance groups in mobile communication system supporting carrier aggregation

A terminal comprising:

• a transceiver configured to transmit and receive a signal;
• and
• a controller configured to:
• control the transceiver to receive, from a base station, radio resource control (RRC) connection reconfiguration information for configuring a secondary cell (SCell), wherein the RRC connection reconfiguration information includes an identifier of a timing advance group (TAG) to which the SCell belongs if the SCell does not belong to a primary TAG (PTAG) to which a primary cell (PCell) belongs and the RRC connection reconfiguration information does not include an identifier of a TAG for the SCell if the SCell belongs to the PTAG,
• control the transceiver to receive, from the base station, a medium access control (MAC) control element (CE) for activating the SCell,
• monitor a physical downlink control channel (PDCCH) for the SCell based on the received MAC CE,
• control the transceiver to receive, from the base station, a physical downlink control channel (PDCCH) order for initiating a random access procedure on the SCell based on the monitoring,
• perform the random access procedure on the SCell based on the PDCCH order, and
• receive, from the base station, a MAC CE including a timing advance command (TAC) for a TAG including the SCell based on the random access procedure from the base station.

A method by a base station, the method comprising:

• transmitting, to a terminal, radio resource control (RRC) connection reconfiguration information for configuring a secondary cell (SCell), wherein the RRC connection reconfiguration information includes an identifier of a timing advance group (TAG) to which the SCell belongs if the SCell does not belong to a primary TAG (PTAG) to which a primary cell (PCell) belongs and the RRC connection reconfiguration information does not include an identifier of a TAG for the SCell if the SCell belongs to the PTAG;
• transmitting, to the terminal, a medium access control (MAC) control element (CE) for activating the SCell;
• transmitting, to the terminal, a physical downlink control channel (PDCCH) order for initiating a random access procedure on the SCell;
• initiating the random access procedure on the SCell based on the PDCCH order;
• and
• transmitting, to the terminal, a MAC CE including a timing advance command (TAC) for a TAG including the SCell based on the random access procedure,
• wherein the PDCCH order is received at the terminal by monitoring a PDCCH for the SCell based on the received MAC CE by the terminal.

A base station comprising:

• a transceiver configured to transmit and receive a signal;
• and
• a controller configured to:
• control the transceiver to transmit, to a terminal, radio resource control (RRC) connection reconfiguration information for configuring a secondary cell (SCell), wherein the RRC connection reconfiguration information includes an identifier of a timing advance group (TAG) to which the SCell belongs if the SCell does not belong to a primary TAG (PTAG) to which a primary cell (PCell) belongs and the RRC connection reconfiguration information does not include an identifier of a TAG for the SCell if the SCell belongs to the PTAG,
• control the transceiver to transmit, to the terminal, a medium access control (MAC) control element (CE) for activating the SCell,
• control the transceiver to transmit, to the terminal, a physical downlink control channel (PDCCH) order for initiating a random access procedure on the SCell,
• initiate the random access procedure on the SCell based on the PDCCH order, and
• control the transceiver to transmit, to the terminal, a MAC CE including a timing advance command (TAC) for a TAG including the SCell based on the random access procedure,
• wherein the PDCCH order is received at the terminal by monitoring a PDCCH for the SCell based on the received MAC CE by the terminal.