Apparatus and method for performing dual connectivity in wireless communication system

A method performed by a network node configured to perform functions of central unit-user plane (CU-UP) of a next generation node B (gNB), the method comprising:

• receiving, through E1 interface, from a central unit-control plane (CU-CP), a bearer context modification request message including cell group information, the cell group information including:
• a cell group identifier (ID) for indicating a cell group being one of a master cell group (MCG) and a secondary cell group (SCG), and
• downlink transmission information being a value indicating a resume of downlink transmission for the cell group, among the value and another value indicating a stop of the downlink transmission, wherein the downlink transmission information is used to resume the downlink transmission stopped before receiving the bearer context modification request message;
• and
• transmitting, through the E1 interface, to the CU-CP, a bearer context modification response message.

A network node configured to perform functions of central unit-control plane (CU-CP) of a next generation node B (gNB), comprising:

• at least one processor;
• and
• memory storing instructions that, when executed by the at least one processor, cause the CU-CP to:
• transmit, through E1 interface, to a central unit-user plane (CU-UP), a bearer context modification request message including cell group information, the cell group information including:
• a cell group identifier (ID) for indicating a cell group being one of a master cell group (MCG) and a secondary cell group (SCG), and
• downlink transmission information being a value indicating a resume of downlink transmission for the cell group, among the value and another value indicating a stop of the downlink transmission, wherein the downlink transmission information is used to resume the downlink transmission stopped before transmitting the bearer context modification request message, and
• receive, through the E1 interface, from the CU-UP, a bearer context modification response message.

A network node configured to perform functions of central unit-user plane (CU-UP) of a next generation node B (gNB), comprising:

• memory storing instructions,
• a transceiver;
• and
• a processor,
• wherein the instructions, when executed by the processor, cause the CU-UP to:
• receive, through E1 interface, from a central unit-control plane (CU-CP), a bearer context modification request message including cell group information, the cell group information including:
• a cell group identifier (ID) for indicating a cell group being one of a master cell group (MCG) and a secondary cell group (SCG), and
• downlink transmission information being a value indicating a resume of downlink transmission for the cell group, among the value and another value indicating a stop of the downlink transmission, wherein the downlink transmission information is used to resume the downlink transmission stopped before receiving the bearer context modification request message, and
• transmit, through the E1 interface, to the CU-CP, a bearer context modification response message.