Radio access network node, core network node, radio terminal, and methods therefor

A control plane node to be located in a core network, the control plane node comprising:

• a memory;
• and
• at least one processor coupled to the memory and configured to receive, from a master Radio Access Network (RAN) node, a PDU Session Resource Modify Indication message requesting modification of a PDU session already established between a radio terminal and a user plane function in the core network, wherein
• the PDU Session Resource Modify Indication message is used to indicate to the core network that the already established PDU session is to be split over a plurality of tunnels, and
• the PDU Session Resource Modify Indication message includes a list of one or more Quality of Service (QoS) flows associated with the split of the already established PDU session.

A secondary Radio Access Network (RAN) node comprising:

• a memory;
• and
• at least one processor coupled to the memory and configured to receive an inter-node message from a master RAN node, the inter-node message requesting allocation of resources for dual connectivity for a radio terminal, wherein
• the inter-node message is also used to indicate to the secondary RAN node that a PDU session already established between the radio terminal and a user plane function in a core network is to be split over a plurality of tunnels, and the inter-node message includes a list of one or more Quality of Service (QoS) flows associated with the split of the already established PDU session.

A radio terminal comprising:

• a memory;
• and
• at least one processor coupled to the memory and configured to receive a Radio Resource Control (RRC) connection reconfiguration message from a master Radio Access Network (RAN) node or a secondary RAN node, the RRC connection reconfiguration message indicating a secondary cell group configuration for dual connectivity, wherein
• the RRC connection reconfiguration message is also used to indicate to the radio terminal that a PDU session already established between the radio terminal and a user plane function in a core network is to be split over a plurality of tunnels, and the RRC connection reconfiguration message includes a list of one or more Quality of Service (QoS) flows associated with the split of the already established PDU session.