Method and apparatus for a master cell group
Embodiments of the present application relate to a method and an apparatus for a master cell group, e.g., a dual active protocol stack (DAPS) handover procedure and a radio link failure (RLF) report mechanism associated with a source link during the DAPS handover procedure under a 3rd Generation Partnership Project (3GPP) 5G New Radio (NR) system or the like. According to an embodiment of the present application, a method can include: receiving configuration information including a timer associated with fast MCG link recovery; receiving a radio resource control (RRC) reconfiguration message including DAPS configuration information; in response to a RLF of a source link for a MCG, initiating a MCG failure information procedure based on the condition that the timer for handover is running or not. In addition, a RLF-report may be reported to a target cell after a UE successfully accesses to the target cell.
1 . A user equipment (UE) for wireless communication, comprising:
at least one memory; and
at least one processor coupled with the at least one memory and configured to cause the UE to:
receive configuration information including a first timer associated with fast master cell group (MCG) link recovery;
receive a first radio resource control (RRC) reconfiguration message including dual active protocol stack (DAPS) configuration information;
perform a DAPS handover procedure;
start a second timer for handover, the second timer for handover based on the DAPS configuration information;
initiate, in response to a radio link failure (RLF) of a source link for a MCG during the DAPS handover procedure, a MCG failure information procedure when the second timer for handover is running; and
start the first timer associated with fast MCG link recovery.
2 . The UE of claim 1 , wherein the at least one processor is configured to cause the UE to:
transmit a MCG failure information message in response to initiating the MCG failure information procedure;
receive a second RRC reconfiguration message, wherein the second RRC reconfiguration message includes a reconfiguration with synchronization information element (IE); and
execute, in response to receiving the second RRC reconfiguration message, a reconfiguration with synchronization procedure and stop performing the DAPS handover procedure.
3 . The UE of claim 1 , wherein the at least one processor is configured to cause the UE to:
transmit a MCG failure information message in response to initiating the MCG failure information procedure;
receive a second RRC reconfiguration message, wherein the second RRC reconfiguration message includes a reconfiguration with synchronization information element (IE); and
ignore, in response to receiving the second RRC reconfiguration message, the second RRC reconfiguration message and continue performing the DAPS handover procedure.
4 . The UE of claim 1 , wherein the at least one processor is configured to cause the UE to:
receive a RRC release message; and
release, in response to receiving the RRC release message, a resource associated with the source link and continue performing the DAPS handover procedure.
5 . The UE of claim 1 , wherein the at least one processor is configured to cause the UE to:
receive a RRC release message; and
ignore, in response to receiving the RRC release message, the RRC release message and continue performing the DAPS handover procedure.
6 . The UE of claim 1 , wherein the at least one processor is configured to cause the UE to:
transmit a MCG failure information message in response to initiating the MCG failure information procedure; and
not initiate, in response to that the first timer associated with fast MCG link recovery expires, a RRC connection re-establishment procedure when performing the DAPS handover procedure.
7 . A user equipment (UE) for wireless communication, comprising:
at least one memory; and
at least one processor coupled with the at least one processor and configured to cause the UE to:
receive a radio resource control (RRC) reconfiguration message including a reconfiguration with synchronization information element (IE) and dual active protocol stack (DAPS) configuration information;
perform a DAPS handover procedure based on the synchronization IE and the DAPS configuration information; and
transmit, in response to a radio link failure (RLF) of a source link for a master cell group (MCG) during the DAPS handover procedure, a report related to the RLF after successfully completing the DAPS handover procedure, wherein the report includes an indication indicating a successful completion of the DAPS handover procedure, a cell identifier (ID) of a source cell, a connection failure type, and a cause for the RLF of the source link.
8 . The UE of claim 7 , wherein the connection failure type is configured as an RLF in source.
9 . The UE of claim 7 , wherein the cause for the RLF of the source link includes at least one of:
an expiry of a first timer for a physical layer problem;
a problem of a random access procedure;
reaching a maximum number of retransmissions;
a failure of a beam failure recovery procedure;
an expiry of a second timer for initiating failure recovery based on triggering a measurement report;
a reception of backhaul (BH) RLF indication; or
a failure of a listen-before-talk (LBT) for the source link.
10 . The UE of claim 7 , wherein the at least one processor is configured to cause the UE to:
receive configuration information including a first timer associated with fast MCG link recovery; and
initiate, in response to the RLF of the source link for the MCG during the DAPS handover procedure, a MCG failure information procedure when the first timer associated with fast MCG link recovery is not running and a second timer for handover is not running.
11 . The UE of claim 10 , wherein the second timer for handover is associated with DAPS configuration information.
12 . A base station for wireless communication, comprising:
at least one memory; and
at least one processor coupled with the at least one processor and configured to cause the base station to:
transmit a user equipment (UE) information request;
receive a UE information response including a report, wherein the report includes information related to a radio link failure (RLF) of a source link for a master cell group (MCG) during a dual active protocol stack (DAPS) handover procedure, wherein the report includes an indication indicating a successful completion of the DAPS handover procedure, a cell identifier (ID) of a source cell, a connection failure type, and a cause for the RLF of the source link; and
transmit a failure indication, wherein the failure indication includes an information element (IE) indicating the successful completion of the DAPS handover procedure.
13 . The base station of claim 12 , wherein the failure indication includes at least one of:
the cell ID of the source cell;
a cell ID of a target cell;
the cause for the RLF of the source link;
a container including RLF-report IE reported from a UE; or
a cell radio network temporary identifier (C-RNTI) in source.
14 . The base station of claim 13 , wherein the cause for the RLF of the source link includes at least one of:
an expiry of a physical layer problem timer;
a problem of a random access procedure;
reaching a maximum number of retransmissions on radio link control (RLC);
a failure of a beam failure recovery procedure;
an expiry of a timer for initiating failure recovery based on triggering a measurement report;
a reception of backhaul (BH) RLF indication; or
a failure of a listen-before-talk (LBT) for the source link.
15 . The base station of claim 13 , wherein the cell ID of the target cell comprises at least one of:
a physical cell identifier (PCI); or
an evolved universal terrestrial radio access network (E-UTRAN) cell global identifier (ECGI).
16 . The base station of claim 12 , wherein the cause for the RLF of the source link includes at least one of:
an expiry of a physical layer problem timer;
a problem of a random access procedure;
reaching a maximum number of retransmissions on radio link control (RLC);
a failure of a beam failure recovery procedure;
an expiry of a timer for initiating failure recovery based on triggering a measurement report;
a reception of backhaul (BH) RLF indication; or
a failure of a listen-before-talk (LBT) for the source link.
17 . The base station of claim 12 , wherein the base station is a target base station for the DAPS handover procedure.
18 . The base station of claim 17 , wherein the at least one processor is configured to cause the base station to transmit the UE information request to a source base station to which a UE is connected.
19 . A method performed by a user equipment (UE), the method comprising:
receiving a radio resource control (RRC) reconfiguration message including a reconfiguration with synchronization information element (IE) and dual active protocol stack (DAPS) configuration information;
performing a DAPS handover procedure based on the synchronization IE and the DAPS configuration information; and
transmitting, in response to a radio link failure (RLF) of a source link for a master cell group (MCG) during the DAPS handover procedure, a report related to the RLF after successfully completing the DAPS handover procedure, wherein the report includes an indication indicating a successful completion of the DAPS handover procedure, a cell identifier (ID) of a source cell, a connection failure type, and a cause for the RLF of the source link.
20 . The method of claim 19 , wherein the connection failure type is configured as an RLF in source.