Master node, secondary node, and methods therefor
A master node (MN) ( 1 ) controls the MN ( 1 ) to enable, for a radio terminal ( 3 ), dual connectivity using a Master Cell Group (MCG) provided by the MN ( 1 ) and a Secondary Cell Group (SCG) provided by a secondary node (SN) ( 2 ). The MN ( 1 ) sends to the SN ( 2 ) a first message related to a modification or release of a configuration or resource in the SN ( 2 ) regarding the dual connectivity. The first message explicitly or implicitly indicates that the modification or release is related to a failure of the MCG or recovery from the failure of the MCG. This, for example, allows the SN to distinguish a message regarding modification or release of an SN configuration (or resource) sent from an MN to the SN for recovery from an MCG failure from other messages.
1. A method for a Secondary node of a dual connectivity with a Master node, the method comprising:
communicating, with a user terminal, using a Secondary Cell Group (SCG), which is a group of serving cells associated with the Secondary node;
receiving a Radio Resource Control (RRC) Transfer message from the Master node if radio link failure is detected for a Master Cell Group (MCG) which is a group of serving cells associated with the Master node, the RRC Transfer message including a Packet Data Convergence Protocol control-plane (PDCP-C) Protocol Data Unit (PDU) encapsulating a RRC Reconfiguration message, the RRC Transfer message including, in addition to the RRC Reconfiguration message, information indicating to the Secondary node that the RRC Reconfiguration message relates to a recovery of the MCG failure; and
transmitting the RRC Reconfiguration message to the user terminal before a release of resources.
2. The method according to claim 1 , further comprising receiving a Release Request message from the Master node.
3. The method according to claim 2 , further comprising releasing the resources based on the Release Request message.
4. A method for a Master node of a dual connectivity with a Secondary node, the method comprising:
communicating, with a user terminal, using an MCG, which is a group of serving cells associated with the Master node; and
transmitting a RRC Transfer message to the Secondary node if radio link failure is detected for the MCG, the RRC Transfer message including a PDCP-C PDU encapsulating a RRC Reconfiguration message, the RRC Transfer message including, in addition to the RRC Reconfiguration message, information indicating to the Secondary node that the RRC Reconfiguration message relates to a recovery of the MCG failure,
wherein the RRC Reconfiguration message is transmitted to the user terminal before a release of resources.
5. The method according to claim 4 , further comprising transmitting a Release Request message to the Secondary node.
6. The method according to claim 5 , wherein the Release Request message causes the Secondary Node to release the resources based on the Release Request message.
7. A Secondary node of a dual connectivity with a Master node, the Secondary node comprising:
at least one memory; and
at least one processor coupled to the memory and configured to:
communicate, with a user terminal, using an SCG, which is a group of serving cells associated with the Secondary node;
receive a RRC Transfer message from the Master node if radio link failure is detected for an MCG which is a group of serving cells associated with the Master node, the RRC Transfer message including a PDCP-C PDU encapsulating a RRC Reconfiguration message, the RRC Transfer message including, in addition to the RRC Reconfiguration message, information indicating to the Secondary node that the RRC Reconfiguration message relates to a recovery of the MCG failure; and
transmit the RRC Reconfiguration message to the user terminal before a release of resources.
8. The Secondary node according to claim 7 , wherein the at least one processor is further configured to receive a Release Request message from the Master node.
9. The Secondary node according to claim 8 , wherein the at least one processor is further configured to release the resources based on the Release Request message.
10. A Master node of a dual connectivity with a Secondary node, the Master node comprising:
at least one memory; and
at least one processor coupled to the memory and configured to:
communicate, with a user terminal, using an MCG, which is a group of serving cells associated with the Master node; and
transmit a RRC Transfer message to the Secondary node if radio link failure is detected for the MCG, the RRC Transfer message including a PDCP-C PDU encapsulating a RRC Reconfiguration message, the RRC Transfer message including, in addition to the RRC Reconfiguration message, information indicating to the Secondary node that the RRC Reconfiguration message relates to a recovery of the MCG failure,
wherein the RRC Reconfiguration message is transmitted to the user terminal before a release of resources.
11. The Master node according to claim 10 , wherein the at least one processor is further configured to transmit a Release Request message to the Secondary node.
12. The Master node according to claim 11 , wherein the Release Request message causes the Secondary Node to release the resources based on the Release Request message.