Method and apparatus for performing dual connectivity in heterogeneous network

A central unit-control plane (CU-CP) included in a secondary node (SN) or secondary gNB (SgNB) in a wireless communication system supporting evolved universal terrestrial radio access and new radio dual connectivity (EN-DC), the CU-CP comprising:

• a transceiver;
• and
• a processor configured to:
• receive, from a master node (MN) or master eNB (MeNB), a first message for requesting the SgNB to allocate a radio resource for a bearer,
• transmit, to a central unit-user plane (CU-UP) included in the SgNB, a second message, including indication information indicating whether a packet data convergence protocol (PDCP) version of the bearer has been changed;
• and
• transmit, to the CU-UP, a third message including count information on a PDCP sequence number (SN) for a packet received through the bearer,
• wherein the indication information is generated based on the first message, and
• wherein the packet received through the bearer is aligned at the CU-UP based on at least one of the indication information or the count information.

A method of a central unit-user plane (CU-UP) included in a secondary node (SN) or secondary gNB (SgNB) in a wireless communication system supporting evolved universal terrestrial radio access and new radio dual connectivity (EN-DC), the method comprising:

• receiving, from a central unit-control plane (CU-CP) included in the SgNB, a second message including indication information indicating whether a packet data convergence protocol (PDCP) version of a bearer has been changed;
• receiving, from the CU-CP, a third message including count information on a PDCP sequence number (SN) for a packet received through the bearer;
• and
• aligning the packet received through the bearer based on at least one of the indication information or the count information, wherein the indication information is generated based on a first message requesting the SgNB to allocate a radio resource for the bearer, the first message being received from a master node (MN) or master eNB (MeNB).

A central unit-user plane (CU-UP) included in a secondary node (SN) or secondary gNB (SgNB) in a wireless communication system supporting evolved universal terrestrial radio access and new radio dual connectivity (EN-DC), the CU-UP comprising:

• a transceiver;
• and
• a processor configured to:
• receive, from a central unit-control plane (CU-CP) included in the SgNB, a second message including indication information indicating whether a packet data convergence protocol (PDCP) version of a bearer has been changed,
• receive, from the CU-CP, a third message including count information on a PDCP sequence number (SN) for a packet received through the bearer, and
• align the packet received through the bearer based on at least one of the indication information or the count information,
• wherein the indication information is generated based on a first message requesting the SgNB to allocate a radio resource for the bearer, the first message being received from a master node (MN) or master eNB (MeNB).