Method and apparatus for failure handling mechanism for CHO program

Abstract

Embodiments of the present application relate to a method and apparatus (900) for a failure handling mechanism for conditional handover (CHO). In accordance with an embodiment of the present application, a user equipment (UE 101) comprises a transceiver (902) and a processor (906) coupled to the transceiver (902); and the processor (906) is configured to: receive, via the transceiver (902), a conditional switching (CHO) configuration associated with a target primary cell group (MCG) and a target secondary cell group (SCG), where the CHO configuration includes a CHO execution condition of the target MCG, and where the target SCG is the same or different (201) as a source SCG of the UE; evaluating the CHO execution condition of the target MCG (202); and executing a CHO procedure for the target MCG in response to the fulfillment of the CHO execution condition for the target MCG (203).

Description

Technical Field

[0001] Embodiments of the present application generally relate to methods and apparatus for a failure handling mechanism for a conditional handoff (CHO) procedure. Background Art

[0002] CHO is defined as a handover performed by a user equipment (UE) when one or more handover execution conditions are met. The UE starts evaluating the one or more handover execution conditions upon receiving one or more CHO configurations and one or more CHO execution conditions, and stops evaluating the one or more CHO execution conditions during CHO execution once the one or more CHO execution conditions are met.

[0003] The next generation radio access network (NG-RAN) supports multi-radio dual connectivity (MR-DC) scenarios. In the MR-DC scenario, a UE with multiple transceivers can be configured to utilize resources provided by two different nodes connected via a non-ideal backhaul. One of the nodes can provide new air interface (NR) access, and the other node can provide evolved universal mobile telecommunications system (UMTS) terrestrial radio access (UTRA) (E-UTRA) or NR access. One node can act as a master node (MN), and the other node can act as a secondary node (SN). The MN and the SN are connected via a network interface (e.g., an Xn interface specified in the third generation partnership project (3GPP) standard document), and at least the MN is connected to the core network. At present, the details of the failure handling mechanism of the CHO procedure in the MR-DC scenario have not been discussed. Summary of the invention

[0004] Some embodiments of the present application provide a user equipment (UE). The UE includes a transceiver and a processor coupled to the transceiver; and the processor is configured to: receive a conditional handover (CHO) configuration associated with a target primary cell group (MCG) and a target secondary cell group (SCG) via the transceiver, wherein the CHO configuration includes a CHO execution condition of the target MCG, and wherein the target SCG is the same as or different from a source SCG of the UE; evaluate the CHO execution condition of the target MCG; and execute a CHO procedure for the target MCG in response to the satisfaction of the CHO execution condition of the target MCG.

[0005] In some embodiments, in response to the UE connecting to a source MCG and in response to the occurrence of a failure on the source SCG, the processor of the UE is configured to: initiate a first SCG failure information procedure to report first information associated with the failure on the source SCG to the source MCG; and suspend the link between the source SCG and the UE.

[0006] In some embodiments, in response to the target SCG being the same as the source SCG, the processor of the UE is configured to perform at least one of: performing a random access (RA) procedure for the target MCG; prohibiting execution of the RA procedure for the target SCG; or in response to successfully completing the RA procedure for the target MCG, transmitting second information associated with a failure on the source SCG to the target MCG via the transceiver.

[0007] In some embodiments, the second information is included in a Radio Resource Control (RRC) Reconfiguration Complete message.

[0008] In some embodiments, the processor of the UE is configured to initiate a second SCG failure information procedure, wherein the second information is included in a SCG failure information message, and wherein the SCG failure information message is transmitted to the target MCG.

[0009] In some embodiments, the second information includes at least one of: a first indication indicating that the failure occurred on the source SCG; a second indication indicating that the failure occurred on the source SCG before executing the CHO procedure on the target MCG; or a third indication indicating that the first information has been transmitted to the source MCG.

[0010] In some embodiments, the CHO configuration includes an RRC configuration of the target SCG, and wherein the processor of the UE is configured to perform at least one of the following: applying the RRC configuration of the target SCG in response to executing the CHO procedure; or continuing to suspend the link between the source SCG and the UE.

[0011] In some embodiments, the processor of the UE is configured to consider the CHO execution condition of the target MCG as satisfied when the UE is suspending the link between the source SCG and the UE.

[0012] In some embodiments, the CHO configuration includes an RRC configuration of the target SCG, and wherein the processor of the UE is configured to: release the RRC configuration of the target SCG; and transmit an RRC message including a fourth indication to the target MCG via the transceiver, wherein the fourth indication indicates at least one of: the RRC configuration of the target SCG is not applied; or the occurrence of the failure on the target SCG.

[0013] In some embodiments, in response to the target SCG being the same as or different from the source SCG, the CHO configuration includes an RRC configuration of the target MCG and an RRC configuration of the target SCG, wherein the RRC configuration of the target SCG is updated based on the RRC configuration of the source SCG.

[0014] In some embodiments, in response to a change in the primary secondary cell group cell (PSCell) of the source SCG or an update of the RRC configuration of the source SCG, the processor of the UE is configured to perform at least one of the following: continuing the CHO procedure for the target MCG; prohibiting the application of the RRC configuration of the target SCG; prohibiting the execution of a random access (RA) procedure for the target SCG; or transmitting third information to the target MCG via the transceiver, wherein the third information is associated with the change of the PSCell of the source SCG or the update of the RRC configuration of the source SCG.

[0015] In some embodiments, the third information is included in a radio resource control (RRC) reconfiguration complete message or a SCG failure information message.

[0016] In some embodiments, in response to a change in the primary secondary cell group cell (PSCell) of the source SCG or an update of the RRC configuration of the source SCG, the processor of the UE is configured to: execute the CHO procedure on the target MCG and the target SCG; apply the updated RRC configuration of the target SCG after the change in the PSCell of the source SCG or the update of the RRC configuration of the source SCG; and transmit fourth information to the target MCG via the transceiver, wherein the fourth information is associated with the change in the PSCell of the source SCG or the update of the RRC configuration of the source SCG.

[0017] In some embodiments, the processor of the UE is configured to store the RRC configuration of the source SCG in response to reception of the CHO configuration or in response to the change of the PSCell of the source SCG or in response to the update of the RRC configuration of the source SCG.

[0018] In some embodiments, in response to a change in the primary secondary cell group cell (PSCell) of the source SCG or an update of the RRC configuration of the source SCG, the processor of the UE is configured to: continue executing the CHO procedure for the target MCG; apply the RRC configuration of the target SCG during the execution of the CHO procedure for the target MCG; and perform a RA procedure for the target SCG.

[0019] Some embodiments of the present application also provide a target master node (MN). The target MN includes a transceiver and a processor coupled to the transceiver; and the processor is configured to: receive a handover request message from a source MN via the transceiver; transmit a handover request confirmation message to the source MN via the transceiver, wherein the handover request confirmation message includes a conditional handover (CHO) configuration associated with a target secondary cell group (SCG) of a user equipment (UE), and wherein the target SCG is the same as or different from the source SCG of the UE; and receive failure related information from the UE via the transceiver.

[0020] In some embodiments, the failure-related information is received after the UE successfully completes a RA procedure to a target MCG.

[0021] In some embodiments, the failure related information is included in a radio resource control (RRC) reconfiguration complete message or a SCG failure information message.

[0022] In some embodiments, in response to the target SCG being the same as the source SCG, the failure-related information is associated with the occurrence of a failure on the source SCG.

[0023] In some embodiments, in response to the target SCG being the same as the source SCG, the failure-related information includes at least one of the following: a first indication indicating that the failure occurred on the source SCG; a second indication indicating that the failure occurred on the source SCG before executing the CHO procedure on the target MCG; or a third indication indicating that first information associated with the failure on the target SCG has been transmitted to the source MCG.

[0024] In some embodiments, the CHO configuration includes an RRC configuration for the target SCG, wherein the processor of the target MN is configured to receive an RRC message including a fourth indication from the UE via the transceiver, and wherein the fourth indication indicates at least one of: the RRC configuration of the target SCG is not applied; or the occurrence of a failure on the target SCG.

[0025] In some embodiments, in response to the target SCG being the same as or different from the source SCG, the CHO configuration includes an RRC configuration of the target MCG and an RRC configuration of the target SCG, wherein the RRC configuration of the target SCG is updated based on the RRC configuration of the source SCG.

[0026] In some embodiments, the failure-related information is associated with a change of a primary secondary cell group cell (PSCell) of the source SCG or an update of an RRC configuration of the source SCG.

[0027] Some embodiments of the present application also provide a source master node (MN). The source MN includes a transceiver and a processor coupled to the transceiver; and the processor is configured to: transmit a handover request message to a target MN via the transceiver; and receive a handover request confirmation message from the target MN via the transceiver, wherein the handover request confirmation message includes a conditional handover (CHO) configuration associated with a target primary cell group (MCG) and a target secondary cell group (SCG) of a user equipment (UE).

[0028] In some embodiments, the processor of the source MN is further configured to receive an indication from the source SN via the transceiver, and wherein the indication indicates at least one of: a change of the primary secondary cell group cell (PSCell) of the source SCG; or an update of the RRC configuration of the source SCG.

[0029] Some embodiments of the present application also provide a source secondary node (SN). The source SN includes a transceiver and a processor coupled to the transceiver; and the processor is configured to: transmit a configuration associated with a change of a primary and secondary cell group cell (PSCell) of a source SCG of a user equipment (UE) or an update of an RRC configuration of the source SCG to the UE via the transceiver; and transmit an indication to a source MN via the transceiver, wherein the indication indicates at least one of the following: a change of a primary and secondary cell group cell (PSCell) of the source SCG; or an update of an RRC configuration of the source SCG.

[0030] Some embodiments of the present application provide a method performed by a UE. The method includes: receiving a conditional handover (CHO) configuration associated with a target primary cell group (MCG) and a target secondary cell group (SCG), wherein the CHO configuration includes a CHO execution condition of the target MCG, and wherein the target SCG is the same as or different from a source SCG of the UE; evaluating the CHO execution condition of the target MCG; and performing a CHO procedure on the target MCG in response to satisfaction of the CHO execution condition of the target MCG.

[0031] Some embodiments of the present application provide a method performed by a target MN. The method includes: receiving a handover request message from a source MN; transmitting a handover request confirmation message to the source MN, wherein the handover request confirmation message includes a conditional handover (CHO) configuration associated with a target secondary cell group (SCG) of a user equipment (UE), and wherein the target SCG is the same as or different from the source SCG of the UE; and receiving failure related information from the UE.

[0032] Some embodiments of the present application provide a method performed by a source MN. The method includes: transmitting a handover request message to a target MN; and receiving a handover request confirmation message from the target MN, wherein the handover request confirmation message includes a conditional handover (CHO) configuration associated with a target primary cell group (MCG) and a target secondary cell group (SCG) of a user equipment (UE).

[0033] Some embodiments of the present application provide a method performed by a source SN. The method includes: transmitting to a user equipment (UE) a configuration associated with a change of a primary and secondary cell group cell (PSCell) of a source SCG of the UE or an update of an RRC configuration of the source SCG; and transmitting to a source MN an indication, wherein the indication indicates at least one of the following: a change of a primary and secondary cell group cell (PSCell) of the source SCG; or an update of an RRC configuration of the source SCG.

[0034] Some embodiments of the present application provide a device for wireless communication. The device includes: a non-transitory computer-readable medium having computer-executable instructions stored thereon; a receiving circuit system; a transmitting circuit system; and a processor coupled to the non-transitory computer-readable medium, the receiving circuit system, and the transmitting circuit system, wherein the computer-executable instructions cause the processor to implement the above-mentioned method performed by a UE or a network node (source MN, target MN, source SN, or target SN).

[0035] The details of one or more examples are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description and drawings, and from the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to describe the manner in which the advantages and features of the present application can be obtained, the description of the present application is presented by reference to specific embodiments of the present application illustrated in the accompanying drawings. These drawings depict only example embodiments of the present application and therefore should not be considered to limit its scope.

[0037] Figure 1 A schematic diagram illustrating a wireless communication system according to some embodiments of the present application.

[0038] Figures 2 to 5 An exemplary procedure for a failure handling mechanism for CHO according to some embodiments of the present application is described.

[0039] Figures 6 to 8 A flow chart illustrating an exemplary procedure for wireless communication according to some embodiments of the present application.

[0040] Fig. 9 A block diagram illustrating an exemplary apparatus according to some embodiments of the present disclosure. DETAILED DESCRIPTION

[0041] The detailed description of the accompanying drawings is intended as a description of the preferred embodiments of the present application, and is not intended to represent the only form in which the present application can be practiced. It should be understood that the same or equivalent functions can be implemented by different embodiments that are intended to be included in the spirit and scope of the present application.

[0042] Reference will now be made in detail to some embodiments of the present application, examples of which are illustrated in the accompanying drawings. To facilitate understanding, embodiments are provided under specific network architectures and new service scenarios (e.g., 3GPP 5G, 3GPP LTE Release 8, etc.). It is considered that, with the development of network architectures and new service scenarios, all embodiments in the present application are also applicable to similar technical problems; and in addition, the terms cited in the present application may be changed, which should not affect the principles of the present application.

[0043] Figure 1 A schematic diagram illustrating a wireless communication system according to some embodiments of the present application;

[0044] As in Figure 1 As shown in FIG. 1 , the wireless communication system 100 may be a dual connectivity system 100 including at least one UE 101, at least one MN 102, and at least one SN 103. Specifically, for illustrative purposes, Figure 1 The dual connectivity system 100 in FIG. 1 includes one UE 101 shown, one MN 102 shown, and one SN 103 shown. Figure 1 A specific number of UEs 101, MNs 102, and SNs 103 are depicted in FIG. 1 , but it is contemplated that any number of UEs 101, MNs 102, and SNs 103 may be included in the wireless communication system 100.

[0045] refer to Figure 1 UE 101 may be connected to MN 102 and SN 103 via a network interface (e.g., a Uu interface specified in a 3GPP standard document). MN 102 and SN 103 may be connected to each other via a network interface, e.g., an Xn interface as specified in a 3GPP standard document for NR-NR DC or NGEN-DC or NE-DC, or an X2 interface as specified in a 3GPP standard document for EN-DC. MN 102 may be connected to SN 103 via a network interface (e.g., a Uu interface as specified in a 3GPP standard document). Figure 1 UE 102 may be configured to utilize resources provided by MN 102 and SN 103 to perform data transmission.

[0046] MN 102 may refer to a radio access node that provides a control plane connection to a core network. In an embodiment of the present application, in an E-UTRA-NR dual connectivity (EN-DC) scenario, MN 102 may be an eNB. In another embodiment of the present application, in a next generation E-UTRA-NR dual connectivity (NGEN-DC) scenario, MN 102 may be an ng-eNB. In yet another embodiment of the present application, in an NR-E-UTRA dual connectivity (NE-DC) scenario or an NR-NR dual connectivity (NR-DC) scenario, MN 102 may be a gNB.

[0047] MN 102 may be associated with a Master Cell Group (MCG). MCG may refer to a serving cell group associated with MN 102 and may include a primary cell (PCell) and any one or more secondary cells (SCells) of the MCG. PCell may provide control plane connectivity to UE 101.

[0048] SN 103 may refer to a radio access node that does not have a control plane connection to the core network but provides additional resources to UE 101. In an embodiment of the present application, in an EN-DC scenario, SN 103 may be an en-gNB. In another embodiment of the present application, in a NE-DC scenario, SN 103 may be an ng-eNB. In yet another embodiment of the present application, in an NR-DC scenario or a NGEN-DC scenario, SN 103 may be a gNB.

[0049] SN 103 may be associated with a secondary cell group (SCG). SCG may refer to a serving cell group associated with SN 103 and may include a primary secondary cell (PSCell) and optionally one or more secondary cells (SCells). The PCell of the MCG and the PSCell of the SCG may also be referred to as a special cell (SpCell).

[0050] In some embodiments of the present application, UE 101 may include a computing device such as a desktop computer, a laptop computer, a personal digital assistant (PDA), a tablet computer, a smart TV (e.g., a TV connected to the Internet), a set-top box, a game console, a security system (including a security camera), a vehicle-mounted computer, a network device (e.g., a router, a switch, and a modem), or the like. In some other embodiments of the present application, UE 101 may include a portable wireless communication device, a smart phone, a cellular phone, a flip phone, a device with a subscriber identity module, a personal computer, a selective call reception circuit system, or any other device capable of sending and receiving communication signals on a wireless network.

[0051] In some other embodiments of the present application, UE 101 includes a wearable device, such as a smart watch, a fitness bracelet, an optical head-mounted display, or the like. In addition, UE 101 may be referred to as a subscriber unit, a mobile device, a mobile station, a user, a terminal, a mobile terminal, a wireless terminal, a fixed terminal, a subscriber station, a user terminal, or a device, or described using other terms used in the art.

[0052] Generally, CHO is performed by the UE when one or more handover execution conditions are met. The UE starts evaluating the execution conditions after receiving the CHO configuration and stops evaluating the execution conditions during CHO execution once the execution conditions are met. The CHO configuration contains the configuration of the CHO candidate cells generated by the candidate BS and the execution conditions generated by the source BS.

[0053] As in intra-NR RAN handover or intra-NR Radio Access Network (RAN) CHO, the preparation and execution phases of the CHO procedure are performed without involving the 5G Core Network (5GC); i.e., preparation messages are exchanged directly between the BSs. The release of resources at the source BS during the conditional handover completion phase is triggered by the target BS, where both the Access and Mobility Management Function (AMF) and the User Plane Function UPF are unchanged.

[0054] Currently, inter-MN handover with or without MN-initiated SN change is used to transfer UE context data from a source MN to a target MN, while the UE context at the SN is retained or moved to another SN. During inter-MN handover, the target MN decides whether to retain or change the SN (or release the SN). Only intra-radio access technology (intra-RAT) inter-MN handover with or without SN change is supported.

[0055] In some cases, the M-NG-RAN node initiates the procedure by sending an S-NODE ADDITION REQUEST message to the S-NG-RAN node. If the CHO information SN addition IE is included in the S-NODE ADDITION REQUEST message, the S-NG-RAN node shall consider that the S-NG-RAN node addition preparation procedure has been triggered as part of the conditional handover. It may use the Source M-NG-RAN Node ID IE and the Source M-NG-RAN Node UE XnAP ID IE to identify other active S-NG-RAN node addition preparations related to this UE. If the Estimated Probability of Arrival IE is included in the CHO information SN addition IE included in the S-NODE ADDITION REQUEST message, the S-NG-RAN node may use that information to allocate the necessary resources for the UE.

[0056] In some other cases, the M-NG-RAN node initiates the procedure by sending an S-NODEMODIFICATION REQUEST message to the S-NG-RAN node. If the CHO information SN modification IE is included in the S-NODEMODIFICATION REQUEST message, the S-NG-RAN node shall consider that the S-NG-RAN node modification preparation procedure initiated by the M-NG-RAN node has been triggered as part of the conditional handover. If the estimated probability of arrival IE is included in the CHO information SN modification IE included in the S-NODEMODIFICATION REQUEST message, the S-NG-RAN node may use that information to allocate the necessary resources to the UE.

[0057] The 3GPP standard document TS38.331 introduces some events of the CHO procedure, for example, CondEvent A3, CondEvent A4, CondEvent A5, CondEvent B1 and CondEvent B2.

[0058] In general, the purpose of the SCG failure information procedure is to notify the E-UTRAN or NR MN that the UE has experienced an SCG failure. SCG failure types include SCG radio link failure, synchronous SCG reconfiguration failure, SCG configuration failure of RRC message on signaling radio bearer (SRB) 3, SCG integrity check failure, and consistent uplink LBT failure on the PSCell for shared spectrum channel access operations. The SCG failure type, measurement results in the MCG and / or test results in the SCG may be included in the SCG failure information message. After the network receives the SCG failure information message, it may trigger the UE to perform an SN release or modification or change procedure. In the case of an SCG failure, the following information may also be included in the SCG failure information message: previous PSCell ID (i.e., PCI); failed PSCell ID (i.e., PCI); time SCG failure and / or RA information.

[0059] Currently, there is a scenario involving a CHO procedure with different SCGs, where the UE performs a CHO procedure from a source PCell with a source SCG to a target PCell with a target SCG, or there is another scenario of a CHO procedure from a single connectivity to an MR-DC connection, where the UE performs a CHO procedure from a source cell to a target PCell with a target SCG. In both of the above scenarios, failure may occur before or after the CHO execution conditions for the PCell are met. The embodiments of the present disclosure are intended to solve such problems in the scenarios mentioned above. More details about the embodiments of the present application will be described below in conjunction with the accompanying drawings.

[0060] Figure 2 An exemplary procedure for performing a CHO procedure according to some embodiments of the present application is described. Figure 2 The exemplary procedure 200 in the embodiment of the present invention may be performed by a UE, for example, Figure 1 Although described with respect to a UE, it should be understood that other devices may be configured to perform the same Figure 2 A similar approach to the one used in this paper.

[0061] In such Figure 2 In the exemplary procedure 200 shown in , in operation 201, the UE may receive a CHO configuration associated with a target MCG and a target SCG. The CHO configuration may include a CHO execution condition of the target MCG. The target SCG may be the same as or different from the source SCG of the UE. In operation 202, the UE may evaluate the CHO execution condition of the target MCG. In operation 203, the UE may perform a CHO procedure on the target MCG in response to satisfaction of the CHO execution condition of the target MCG.

[0062] In some embodiments, in response to the UE connecting to the source MCG and in response to the occurrence of a failure at the source SCG, the UE may initiate an SCG failure information procedure (e.g., Figure 6 ), to report information associated with the failure on the source SCG to the source MCG (represented as information #1 for simplicity), and the link between the source SCG and the UE may be suspended. In an embodiment, while the UE is suspending the link between the source SCG and the UE, the UE may regard the CHO execution condition of the target MCG as satisfied.

[0063] In some embodiments, when the target SCG is the same as the source SCG, the UE may perform at least one of the following:

[0064] (1) Perform RA procedure on the target MCG;

[0065] (2) prohibit the execution of RA proceedings against the target SCG; or

[0066] (3) In response to successfully completing the RA procedure to the target MCG, transmit information associated with the failure on the source SCG to the target MCG (denoted as information #2 for simplicity). In an embodiment, information #2 is included in the RRC reconfiguration complete message (e.g., in the example of Figure 6 ) in option 1 of operation 621 shown in .

[0067] In some embodiments, in the case where the target SCG is the same as the source SCG, the UE may initiate another SCG failure information procedure (e.g., Figure 6). Information #2 may be included in an SCG Failure Information message. The SCG Failure Information message may be transmitted to the target MCG.

[0068] In some embodiments, information #2 may include at least one of the following:

[0069] (1) An indication that a failure occurred on the source SCG;

[0070] (2) an indication that a failure occurred on the source SCG before executing the CHO procedure on the target MCG; or

[0071] (3) An indication that information #1 has been transmitted to the source MCG.

[0072] In some embodiments, when the target SCG is the same as the source SCG, the CHO configuration includes the RRC configuration of the target SCG, and the UE may perform at least one of the following:

[0073] (1) applying the RRC configuration of the target SCG in response to executing the CHO procedure; or

[0074] (2) Continue to suspend the link between the source SCG and the UE. In an embodiment, when the UE suspends the link between the source SCG and the UE, the UE may regard the CHO execution condition of the target MCG as satisfied. Figure 6 Specific examples are described in Option 1 and Option 2 of operation 621 in the embodiments of the present invention.

[0075] In some embodiments, when the target SCG is the same as the source SCG, the CHO configuration includes the RRC configuration of the target SCG, and the UE may release the RRC configuration of the target SCG and transmit an RRC message including another indication to the target MCG. The other indication may indicate at least one of the following: the RRC configuration of the target SCG is not applied; or the occurrence of a failure on the target SCG. In the following Figure 6 A specific example is described in Option 3 of operation 621 of the embodiments.

[0076] In some embodiments, when the target SCG is the same as or different from the source SCG, the CHO configuration includes the RRC configuration of the target MCG and the RRC configuration of the target SCG. The RRC configuration of the target SCG may be updated based on the RRC configuration of the source SCG. For example, the RRC configuration of the target SCG may be named as the "RRC incremental configuration" or "RRC differential configuration" or the like of the target SCG. Figure 8 Specific examples are described in the embodiments of the present invention.

[0077] In some embodiments, in response to a change in the PSCell of the source SCG or an update of the RRC configuration of the source SCG, the UE may perform at least one of the following:

[0078] (1) Continue the CHO procedure for the target MCG;

[0079] (2) Prohibit the application of the RRC configuration of the target SCG;

[0080] (3) prohibit the execution of RA proceedings against the target SCG; or

[0081] (4) Transmitting information associated with the change of the PSCell of the source SCG or the update of the RRC configuration of the source SCG (represented as information #3 for simplicity) to the target MCG (e.g., in Figure 8 Option (2) as shown in operation 8202B).

[0082] For example, information #3 may be included in an RRC reconfiguration complete message or an SCG failure information message.

[0083] In some embodiments, in response to a change in the PSCell of the source SCG or an update in the RRC configuration of the source SCG, the UE may: perform a CHO procedure on the target MCG and the target SCG; apply the updated RRC configuration of the target SCG after the change in the PSCell of the source SCG or the update in the RRC configuration of the source SCG; and transmit information (represented as information #4 for simplicity) to the target MCG (e.g., in the example Figure 8 ). Information #4 may be associated with “change of PSCell of source SCG” or “update of RRC configuration of source SCG”. For example, the updated RRC configuration of target SCG is updated based on the RRC configuration of source SCG and the RRC incremental configuration of target SCG.

[0084] In some embodiments, the UE may store the RRC configuration of the source SCG in response to reception of the CHO configuration or in response to a change of the PSCell of the source SCG or in response to an update of the RRC configuration of the source SCG.

[0085] In some embodiments, in response to a change in the PSCell of the source SCG or an update of the RRC configuration of the source SCG, the UE may: continue to perform a CHO procedure to the target MCG; apply the RRC configuration of the target SCG during the CHO procedure to the target MCG; and perform a RA procedure to the target SCG. Figure 8 Specific examples are described in the embodiments of the present invention.

[0086] Figure 3 An exemplary procedure for receiving failure-related information according to some embodiments of the present application is described. Figure 3 The exemplary procedure 300 in the embodiment of the present invention may be performed by the target MN, for example, Figure 1 Although described with respect to a target MN, it should be understood that other devices may be configured to perform the same Figure 3 A similar approach to the one used in this paper.

[0087] In such as Figure 3 In the exemplary procedure 300 shown in FIG. 1 , in operation 301, the target MN may receive a message from a source MN (e.g., Figure 1 SN 103 shown in FIG. 1 receives the handover request message. In operation 302, the target MN may transmit a handover request confirmation message to the source MN. The handover request confirmation message may include a message with the UE (e.g., Figure 1 3. The target SCG may be the same as or different from the source SCG of the UE. In operation 302, the target MN may receive failure related information from the UE.

[0088] In some embodiments, the failure-related information is received after the UE successfully completes the RA procedure to the target MCG.

[0089] In some embodiments, the failure related information is included in an RRC reconfiguration complete message or an SCG failure information message.

[0090] In some embodiments, where the target SCG is the same as the source SCG, the failure-related information (eg, information #2) is associated with the occurrence of the failure on the source SCG.

[0091] In some embodiments, when the target SCG is the same as the source SCG, the failure-related information (e.g., information #2) includes at least one of the following:

[0092] (1) an indication that a failure occurred on the target SCG;

[0093] (2) an indication that a failure occurred on the source SCG before executing the CHO procedure on the target MCG; or

[0094] (3) An indication that first information associated with a failure at the target SCG has been transmitted to the source MCG.

[0095] In some embodiments, the CHO configuration includes an RRC configuration of the target SCG, and the target MN may receive an RRC message from the UE including another indication. The other indication may indicate at least one of: the RRC configuration of the target SCG is not applied; or a failure occurs on the target SCG. Figure 6 A specific example is described in Option 3 of operation 621 of the embodiments.

[0096] In some embodiments, when the target SCG is the same as or different from the source SCG, the CHO configuration includes the RRC configuration of the target MCG and the RRC configuration of the target SCG. The RRC configuration of the target SCG is updated based on the RRC configuration of the source SCG. The RRC configuration of the target SCG may be named as the "RRC incremental configuration" or "RRC differential configuration" or the like of the target SCG. Figure 8 Specific examples are described in the embodiments of the present invention.

[0097] In some embodiments, the failure-related information is associated with a change in the PSCell of the source SCG or an update of the RRC configuration of the source SCG, for example Figure 8 Option (2) or option (3) in the embodiment.

[0098] Figure 4 An exemplary procedure for transmitting a handover request message according to some embodiments of the present application is described. Figure 4 The exemplary process 400 in the embodiment of the present invention may be performed by a source MN, for example, Figure 8 Although described with respect to the source SN, it should be understood that other devices may be configured to perform the same Figure 4 A similar approach to the one used in this paper.

[0099] In such Figure 4 In the exemplary procedure 400 shown in FIG. 4 , in operation 401, the source MN may send a message to the target MN (e.g., Figure 8 805) shown in FIG. 802. In operation 402, the source MN may receive a handover request confirmation message from the target MN. The handover request confirmation message includes a message sent to the UE (e.g., Figure 8 The CHO configuration associated with the target MCG and target SCG of the UE 801 shown in FIG. The target SCG may be the same as or different from the source SCG of the UE.

[0100] In some embodiments, the source MN may receive an indication from the source SN. The indication may indicate at least one of: a change in the primary and secondary cell group cell (PSCell) of the source SCG; or an update of the RRC configuration of the source SCG. Figure 8 A specific example is described in option (1) of the embodiments.

[0101] Figure 5 An exemplary procedure for transmitting an indication according to some embodiments of the present application is described. Figure 5 The exemplary process 500 in the embodiment of may be performed by a source SN, such as Figure 8 Although described with respect to a source SN, it should be understood that other devices may be configured to perform the same Figure 5A similar approach to the one used in this paper.

[0102] In such Figure 5 In the exemplary procedure 500 shown in FIG. 5 , in operation 501, the source SN may transmit to the UE a message related to the UE (e.g., Figure 8 In operation 502, the source SN may send a configuration associated with a change of the PSCell of the source SCG of the UE 801 shown in FIG. 8 or an update of the RRC configuration of the source SCG. Figure 8 The source MN 802 shown in FIG. 8 transmits an indication. The indication may indicate at least one of the following: a change in the PSCell of the source SCG; or an update of the RRC configuration of the source SCG. Figure 8 A specific example is described in option (1) of the embodiments.

[0103] The details described in all other embodiments of this application apply to Figures 2 to 5 The embodiments shown in any one of the embodiments. It should be understood by those skilled in the art that without departing from the spirit and scope of the present disclosure, Figures 2 to 5 The sequence of operations in any of the exemplary procedures 200 to 500 in the embodiment may be changed, and may be eliminated or modified. Figures 2 to 5 Some of the operations in any of the exemplary procedures 200 to 500 in.

[0104] The following describes Figures 2 to 5 In the specific embodiments shown and described in the specification, the UE and the network nodes (eg, source MN, target MN, source SN and / or target SN) perform the following operations.

[0105] Currently, there may be a situation where the CHO procedure includes a target SCG that is the same as the source SCG, and the CHO execution condition of the PCell is met when the UE suspends the link between the source SCG and the UE due to, for example, RLF on the source SCG. For example, in one case, the UE may initiate the SCG failure information procedure and suspend the link between the source SCG and the UE, for example when RLF on the SCG is detected. The CHO execution condition may be met while the UE still suspends the SCG link. In another case, the SCG is deactivated and RLF or beam failure may be detected. The CHO execution condition may be met when RLF or beam failure is detected for the deactivated SCG. Therefore, it is necessary to solve the problem of how to deal with the MCG and SCG included in the CHO configuration when the CHO execution condition is met while the UE is still suspending the link between the source SCG and the UE.

[0106] Figure 6 and 7 The embodiments can solve the above-mentioned problems. For example, Figure 6In the embodiment of , the UE continues to perform the CHO procedure in the above situation. Figure 7 In some embodiments, even if the CHO execution condition is met in the above situation, the UE will not perform the CHO procedure. Figure 7 In some other embodiments, when the UE suspends the link between the source SCG and the UE in the above situation, the UE will stop evaluating the CHO execution condition.

[0107] Figure 6 Flowchart illustrating an exemplary procedure 600 for wireless communication according to some embodiments of the present application. Operations 611 to 622 may be performed in the exemplary procedure 600. Figure 6 In the CHO procedure described in the embodiment, the target SCG of the UE is the same as the source SCG of the UE.

[0108] In operation 611, the UE 601 in the RRC connected state accesses its serving BS, that is, the source MN 602. For example, DC (dual connectivity) may be configured for the UE 601. The UE 601 may report measurement results to the source MN 602.

[0109] In operation 612, based on the measurement result, the source MN 602 may determine to hand over the UE 601 to the target MN 605 via a CHO procedure.

[0110] In operation 613, the source MN 602 may transmit a handover request message to the target MN 605. For example, the source MN 602 may instruct the target MN 605 to prepare a target SCG.

[0111] In operation 614, after the target MN 605 receives the handover request message from the source MN 602, the target MN 605 transmits a request message (e.g., an SgNB add request message or an SN modify request message) to the target SN 604 via the Xn interface. In some embodiments, if the CHO information SN add IE is included in the request message transmitted in operation 614, the target SN 604 should consider that the SN (S-NG-RAN node) add preparation procedure has been triggered as part of the CHO procedure. It can use the source M-NG-RAN node ID IE and the source M-NG-RAN node UE XnAP ID IE to identify other active S-NG-RAN node add preparations related to the UE 601. In some embodiments, if the estimated arrival probability IE is included in the CHO information SN add IE included in the request message transmitted in operation 614, the S-NG-RAN node can use the information to allocate necessary resources for the UE 601.

[0112] In operation 615, the target SN 604 transmits a confirmation message (e.g., an SgNB add request confirmation message or an SgNB modify request confirmation message) to the target MN 605. The RRC configuration of the target SCG may be included in the confirmation message.

[0113] In operation 616, after receiving the confirmation message from the target SN 604, the target MN 605 transmits a handover request confirmation message including the CHO configuration associated with the target SCG to the source MN 602.

[0114] In operation 617, after receiving the handover request confirm message from the target MN 605, the source MN 602 transmits an RRC reconfiguration message including the CHO configuration associated with the target SCG to the UE 601.

[0115] In operation 618, after receiving the RRC reconfiguration message from the source MN 602, the UE 601 starts evaluating the CHO execution condition of the target MCG upon receiving the CHO configuration in the RRC reconfiguration message. The target SCG included in the CHO configuration may be the same as the source SCG of the UE 601. The UE 601 may be notified by the network that the configured target SCG included in the CHO configuration is the same as the source SCG.

[0116] In operation 619, UE 601 initiates the SCG failure information procedure to report information related to the failure occurring on the source SCG (e.g., information #1). In some embodiments, UE 601 may initiate the SCG failure information procedure when one of the following conditions is met:

[0117] (1) When the RLF of the source SCG is detected;

[0118] (2) When the beam failure of the PSCell is detected while the source SCG is deactivated;

[0119] (3) During reconfiguration in case of synchronization failure of the source SCG;

[0120] (4) When the source SCG configuration fails; or

[0121] (5) When there is an integrity check failure indication regarding SRB3 from the lower layer of the source SCG.

[0122] In operation 620, when the UE 601 initiates the SCG failure information procedure to report SCG failure related information (e.g., information #1) due to one of the following conditions, the UE 601 may suspend the link between the source SCG and the UE 601:

[0123] (1) When the RLF of the source SCG is detected;

[0124] (2) During reconfiguration in case of synchronization failure of the source SCG;

[0125] (3) When the source SCG configuration fails; or

[0126] (4) When there is an integrity check failure indication regarding SRB3 from the lower layer of the source SCG.

[0127] In operation 621, the UE 601 regards the CHO execution condition as satisfied, and the UE 601 triggers the CHO procedure. The following options may exist in different embodiments, namely, option 1, option 2, and option 3.

[0128] (1) Option 1: UE 601 performs a CHO procedure toward the target MCG (i.e., PCell). However, UE 601 will not perform a RA procedure for the target SCG (which is the same as the source SCG), i.e., the PSCell. After UE 601 successfully accesses the target PCell via the RA procedure, UE 601 may transmit an RRC reconfiguration complete message to the target MN 605, the message including information associated with the failure on the source SCG. The information (e.g., information #2) may include at least one of the following: the failure occurred on the source SCG; the failure occurred on the source SCG before performing the CHO procedure; or the SCG failure information has been transmitted to the source MN 602. In Option 1, the RRC configuration associated with the target SCG may be applied, and UE 601 may suspend the link between the target SCG and UE 601.

[0129] (2) Option 2: UE 601 performs a CHO procedure toward the target MCG (i.e., PCell). UE 601 will not perform a RA procedure to the target SCG (which is the same as the source SCG), i.e., the PSCell. After UE 601 successfully accesses the PCell, the SCG Failure Information procedure will be triggered. UE 601 transmits an SCG Failure Information message to the target MN 605, which includes information associated with the failure on the source SCG (e.g., information #2). In Option 2, the RRC configuration associated with the target SCG may be applied, and UE 601 may suspend the link between the target SCG and UE 601.

[0130] (3) Option 3: UE 601 performs a CHO procedure toward the target MCG (i.e., PCell), but does not apply the RRC configuration associated with the target SCG. UE 601 may notify the target MN 605, for example, via an RRC reconfiguration complete message or an SCG failure information message, that the RRC configuration associated with the target SCG was not applied because the failure occurred on the source SCG. In option 3, UE 601 may release the RRC configuration associated with the target SCG.

[0131] In operation 622, the target MN 605 may reconfigure the target SCG to the UE 601.

[0132] Figure 7 Flowchart illustrating an exemplary procedure 700 for wireless communication according to some embodiments of the present application. Operations 711 to 721B may be performed in the exemplary procedure 700. Figure 7 In the CHO procedure described in the embodiment, the target SCG of the UE is the same as the source SCG of the UE.

[0133] In operation 711, UE 701 in an RRC connected state accesses its serving BS, that is, source MN 702. For example, DC (dual connectivity) may be configured for UE 701. UE 701 may report measurement results to source MN 702.

[0134] In operation 712, based on the measurement result, the source MN 702 may determine to hand over the UE 701 to the target MN 705 via a CHO procedure.

[0135] In operation 713, the source MN 702 may transmit a handover request message to the target MN 705. For example, the source MN 702 may instruct the target MN 705 to prepare a target SCG.

[0136] In operation 714, after the target MN 705 receives the handover request message from the source MN 702, the target MN 705 transmits a request message (e.g., an SgNB add request message or an SN modify request message) to the target SN 704 via the Xn interface. In some embodiments, if the CHO information SN add IE is included in the request message transmitted in operation 714, the target SN 704 should consider that the SN (S-NG-RAN node) add preparation procedure has been triggered as part of the CHO procedure. It can use the source M-NG-RAN node ID IE and the source M-NG-RAN node UE XnAP ID IE to identify other active S-NG-RAN node add preparations related to the UE 701. In some embodiments, if the estimated arrival probability IE is included in the CHO information SN add IE included in the request message transmitted in operation 714, the S-NG-RAN node can use the information to allocate necessary resources for the UE 701.

[0137] In operation 715, the target SN 704 transmits a confirmation message (e.g., an SgNB add request confirmation message or an SgNB modify request confirmation message) to the target MN 705. The RRC configuration of the target SCG may be included in the confirmation message.

[0138] In operation 716, after receiving the confirmation message from the target SN 704, the target MN 705 transmits a handover request confirmation message including the CHO configuration associated with the target SCG to the source MN 702.

[0139] In operation 717, after receiving the handover request confirm message from the target MN 705, the source MN 702 transmits an RRC reconfiguration message including the CHO configuration associated with the target SCG to the UE 701.

[0140] In operation 718, after UE 701 receives the RRC reconfiguration message from source MN 702, UE 701 starts evaluating the CHO execution condition of the target MCG upon receiving the CHO configuration in the RRC reconfiguration message. The target SCG included in the CHO configuration may be the same as the source SCG of UE 701. UE 701 may be notified by the network that the configured target SCG included in the CHO configuration is the same as the source SCG.

[0141] In operation 719, UE 701 may initiate an SCG failure information procedure to report information related to a failure occurring on the source SCG (e.g., information #1). UE 701 may initiate an SCG failure information procedure when one of the following conditions is met:

[0142] (1) When the RLF of the source SCG is detected;

[0143] (2) When the beam failure of the PSCell is detected while the source SCG is deactivated;

[0144] (3) During reconfiguration in case of synchronization failure of the source SCG;

[0145] (4) When the source SCG configuration fails; or

[0146] (5) When there is an integrity check failure indication regarding SRB3 from the lower layer of the source SCG.

[0147] In operation 720, when the UE 701 initiates the SCG failure information procedure to report SCG failure related information (e.g., information #1) due to one of the following conditions, the UE 701 may suspend the link between the source SCG and the UE 701:

[0148] (1) When the RLF of the source SCG is detected;

[0149] (2) During reconfiguration in case of synchronization failure of the source SCG;

[0150] (3) When the source SCG configuration fails; or

[0151] (4) When there is an integrity check failure indication regarding SRB3 from the lower layer of the source SCG.

[0152] After operation 720, there may be the following two options in different embodiments, namely, operation 721A or operation 721B.

[0153] In operation 721A (optional, which is marked as a dotted line), UE 701 continues to evaluate the CHO execution condition. However, even if the CHO execution condition is satisfied, UE 701 does not perform the CHO procedure. UE 701 may further notify source MN 702 that the CHO execution condition is satisfied.

[0154] In operation 721B (optional, which is marked as a dotted line), when UE 701 hangs up the link between the source SCG and UE 701, UE 701 will stop evaluating the CHO execution condition of the target MCG.

[0155] Currently, there may be a case of a CHO procedure with different SNs, where the UE performs a CHO procedure from a source PCell having a source SCG in a source SN (e.g., SN#1) to a target PCell having a target SCG in a target SN (e.g., SN#2). There may be another case of a CHO procedure from single connectivity to (MR-)DC connectivity, where the UE performs a CHO procedure from a source PCell to a target PCell having an SCG in an SN. Failures may occur during the CHO procedure. Therefore, there is a need to solve the problem of how to avoid failures during the CHO procedure. Figure 8 The embodiments can solve the above-mentioned problems.

[0156] Figure 8 Flowchart illustrating an exemplary procedure 800 for wireless communication according to some embodiments of the present application. Operations 811 to 8203B may be performed in the exemplary procedure 800. Figure 8 In the CHO procedure described in the embodiments, the target SCG of the UE may be the same as or different from the source SCG of the UE.

[0157] In operation 811, UE 801 in an RRC connected state accesses its serving BS, that is, source MN 802. For example, DC (dual connectivity) may be configured for UE 801. UE 801 may report measurement results to source MN 802.

[0158] In operation 812, based on the measurement result, the source MN 802 may determine to hand over the UE 801 to the target MN 805 via a CHO procedure.

[0159] In operation 813, the source MN 802 may transmit a handover request message to the target MN 805. For example, the source MN 802 may instruct the target MN 805 to prepare a target SCG.

[0160] In operation 814, after the target MN 805 receives the handover request message from the source MN 802, the target MN 805 transmits a request message (e.g., an SgNB add request message or an SN modify request message) to the target SN 804 via the Xn interface. In some embodiments, if the CHO information SN add IE is included in the request message transmitted in operation 814, the target SN 804 should consider that the SN (S-NG-RAN node) add preparation procedure has been triggered as part of the CHO procedure. It can use the source M-NG-RAN node ID IE and the source M-NG-RAN node UE XnAP ID IE to identify other active S-NG-RAN node add preparations related to the UE 801. In some embodiments, if the estimated arrival probability IE is included in the CHO information SN add IE included in the request message transmitted in operation 814, the S-NG-RAN node can use the information to allocate necessary resources for the UE 801.

[0161] In operation 815, the target SN 804 transmits a confirmation message (e.g., an SgNB add request confirmation message or an SgNB modify request confirmation message) to the target MN 805. The RRC configuration associated with the target SCG may be included in the confirmation message. In some cases, the target SCG may be the same as the source SCG of the UE 801. In some cases, the target SCG may be different from the source SCG of the UE 801.

[0162] In operation 816, after receiving the confirmation message from the target SN 804, the target MN 805 transmits a handover request confirmation message including a CHO configuration associated with the target SCG to the source MN 802. For example, the CHO configuration may include an RRC configuration of the target MCG and an RRC configuration of the target SCG. The RRC configuration of the target SCG (e.g., an RRC incremental configuration) may be updated based on the RRC configuration of the source SCG.

[0163] In operation 817, after receiving the handover request confirm message from the target MN 805, the source MN 802 transmits an RRC reconfiguration message including the CHO configuration associated with the target SCG to the UE 801.

[0164] In operation 818, after the UE 801 receives the RRC reconfiguration message, the UE 801 starts evaluating the CHO execution condition of the target MCG upon receiving the CHO configuration associated with the target SCG.

[0165] In operation 819, source SN 803 configures UE 801 for the change of PSCell of source SCG without participation of source MN 802. Alternatively, in operation 819, RRC configuration of source SCG is reconfigured by source SN 803, i.e., RRC configuration of source SCG is updated without participation of source MN 802.

[0166] After operation 819, there may be the following four options, ie, option a to option d, in different embodiments, where at least one of operations 8201 to 8203B may be performed. Operations 8201 to 8203B are optional and are marked as dashed lines.

[0167] Option a: In operation 8201, the source SN 803 may indicate to the source MN 802 in response to a PSCell change or an updated configuration associated with the source SCG. For example, the source MN 802 may receive an indication from the source SN 803, and the indication may indicate at least one of: a change in the PSCell of the source SCG; or an update of the RRC configuration of the source SCG.

[0168] Option b: In operation 8202A, when UE 801 performs a CHO procedure to the target MCG, the RRC configuration associated with the target SCG will not be applied. In operation 8202B, UE 801 reports relevant information to the target MN 805 (i.e., target PCell) via an RRC reconfiguration complete message or an SCG failure information message. For example, UE 801 reports information (e.g., information #3) to the target MN 805, which is associated with a change of the PSCell of the source SCG or an update of the RRC configuration of the source SCG.

[0169] Option c: In operation 8202A, UE 801 performs a CHO procedure for the target MCG. During the CHO procedure, the RRC configuration associated with the target SCG will be applied based on the RRC configuration associated with the latest source SCG (e.g., the new source SCG after the change of the PSCell of the source SCG) or based on the updated RRC configuration associated with the source SCG after the update. In operation 8202B, after UE 801 successfully accesses the target PCell, UE 801 reports relevant information to the target MN 805 via an RRC reconfiguration completion message or an SCG failure information message. For example, UE 801 reports information (e.g., information #4) to the target MN 805, which is associated with the change of the PSCell of the source SCG or the update of the RRC configuration of the source SCG.

[0170] Option d: In operation 8203A, UE 801 performs a CHO procedure to the target MCG. During the CHO procedure, the RRC configuration associated with the target SCG will be applied based on the RRC configuration associated with the old source SCG. In other words, despite the change of the PSCell of the source SCG or the update of the RRC configuration of the source SCG, the RRC configuration associated with the target SCG is applied based on "the RRC configuration associated with the original (old) source SCG before the change of the PSCell of the source SCG or the update of the RRC configuration of the source SCG". In operation 8203B, UE 801 performs a RA procedure towards the target SCG. In some embodiments of option (4), UE 801 may store the RRC configuration associated with the original source SCG in response to: reception of the CHO configuration associated with the target SCG, or a change of the PSCell of the source SCG, or an update of the RRC configuration of the source SCG.

[0171] The details described in all other embodiments of the present disclosure apply to Figures 6 to 8 The embodiments shown in any one of the embodiments. It should be understood by those skilled in the art that without departing from the spirit and scope of the present disclosure, Figures 6 to 8 The sequence of operations in any of the exemplary procedures 600 to 800 in the embodiment may be changed, and may be eliminated or modified. Figures 6 to 8 Some of the operations in any of the exemplary procedures 600 to 800 in.

[0172] Fig. 9 A block diagram illustrating an exemplary device 900 according to some embodiments of the present disclosure. Fig. 9 As shown in , the apparatus 900 may include at least one processor 906 and at least one transceiver 902 coupled to the processor 906.

[0173] Although in this figure, elements such as at least one transceiver 902 and processor 906 are described in the singular, plural forms are contemplated unless limitation to the singular is explicitly stated. In some embodiments of the present application, the transceiver 902 may be divided into two devices, such as a receive circuit system and a transmit circuit system. In some embodiments of the present application, the apparatus 900 may further include an input device, a memory, and / or other components.

[0174] In some embodiments of the present application, the device 900 may be a UE, a target MN, a source MN, a target SN, or a source SN. The transceiver 902 and the processor 906 may interact with each other to perform the operations described above with respect to the UE, the target MN, the source MN, the target SN, or the source SN, for example, Figures 1 to 8 Any one of .

[0175] In some embodiments of the present application, the device 900 may further include at least one non-transitory computer-readable medium. For example, in some embodiments of the present disclosure, the non-transitory computer-readable medium may store thereon computer-executable instructions to enable the processor 906 to implement the method for the UE as described above. For example, when the computer-executable instructions are executed, the processor 906 interacts with the transceiver 902 to perform Figures 1 to 8 The operations described in UE, target MN, source MN, target SN or source SN.

[0176] It will be appreciated by those of ordinary skill in the art that the operations or steps of the methods described in conjunction with the aspects disclosed herein may be directly embodied in hardware, a software module executed by a processor, or a combination of the two. The software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. Additionally, in some aspects, the operations or steps of the methods may reside as one or any combination or set of codes and / or instructions on a non-transitory computer-readable medium that may be incorporated into a computer program product.

[0177] Although the present disclosure has been described with specific embodiments of the present disclosure, it is apparent that many alternatives, modifications, and variations may be apparent to those skilled in the art. For example, in other embodiments, the various components of the embodiments may be interchangeable, added, or replaced. In addition, all elements of each figure are not necessary for the operation of the disclosed embodiments. For example, it will enable a person of ordinary skill in the art of the disclosed embodiments to make and use the teachings of the present disclosure by simply adopting the elements of the independent claims. Therefore, the embodiments of the present disclosure set forth herein are intended to be illustrative, rather than restrictive. Various changes may be made without departing from the spirit and scope of the present disclosure.

[0178] In this document, the term "includes, including" or any other variant thereof is intended to cover non-exclusive inclusion, so that the process, method, article or equipment comprising a series of elements not only includes those elements, but also may include other elements that are not explicitly listed or inherent to this process, method, article or equipment. In the absence of more constraints, an element starting with "a, an" or the like does not exclude the presence of additional identical elements in the process, method, article or equipment comprising the element. In addition, the term "another" is defined as at least the second or more. The term "having" and the like as used herein are defined as "including". For example, the expression of "A and / or B" or "at least one of A and B" may include any and all combinations of words enumerated together with the expression. For example, the expression "A and / or B" or "at least one of A and B" may include A, B or both A and B. The wording "first", "second" or the like is only used to clearly illustrate the embodiments of the present application, and is not used to limit the substantive content of the present application.

Claims

1. A user equipment UE, comprising: Transceiver; and a processor coupled to the transceiver, wherein the processor is configured to: Receiving, via the transceiver, a conditional handover (CHO) configuration associated with a target primary cell group (MCG) and a target secondary cell group (SCG), wherein the CHO configuration includes a CHO execution condition of the target MCG, and wherein the target SCG is the same as or different from a source SCG of the UE; evaluating the CHO execution condition of the target MCG; and A CHO procedure for the target MCG is executed in response to satisfaction of the CHO execution condition of the target MCG.

2. The UE of claim 1 , wherein in response to the UE connecting to a source MCG and in response to an occurrence of a failure on the source SCG, the processor of the UE is configured to: Initiating a first SCG failure information procedure to report first information associated with the failure on the source SCG to the source MCG; and Suspend the link between the source SCG and the UE.

3. The UE according to claim 2, wherein: In response to the target SCG being the same as the source SCG, the processor of the UE is configured to perform at least one of the following: Execute a random access RA procedure on the target MCG; prohibiting the conduct of RA proceedings against the target SCG; or In response to successfully completing the RA procedure to the target MCG, second information associated with the failure on the source SCG is transmitted to the target MCG via the transceiver. The UE according to claim 3 , wherein the second information is included in a Radio Resource Control (RRC) Reconfiguration Complete message.

5. The UE according to claim 3, wherein the processor of the UE is configured to initiate a second SCG failure information procedure, wherein the second information is included in an SCG failure information message, and wherein the SCG failure information message is transmitted to the target MCG.

6. The UE according to any one of claims 3 to 5, wherein the second information comprises at least one of the following: a first indication indicating that the failure occurred on the source SCG; a second indication indicating that the failure occurred on the source SCG before executing the CHO procedure on the target MCG; or A third indication indicating that the first information has been transmitted to the source MCG.

7. The UE of claim 3, wherein the CHO configuration comprises an RRC configuration of the target SCG, and wherein the processor of the UE is configured to perform at least one of: applying the RRC configuration of the target SCG in response to performing the CHO procedure; or Continue to suspend the link between the source SCG and the UE.

8. A UE according to claim 2 or claim 7, wherein the processor of the UE is configured to regard the CHO execution condition of the target MCG as satisfied when the UE is suspending the link between the source SCG and the UE.

9. The UE of claim 3, wherein the CHO configuration comprises an RRC configuration of the target SCG, and wherein the processor of the UE is configured to: releasing the RRC configuration of the target SCG; and An RRC message including a fourth indication is transmitted to the target MCG via the transceiver, wherein the fourth indication indicates at least one of: the RRC configuration of the target SCG is not applied; or the occurrence of the failure on the target SCG.

10. The UE according to claim 1, wherein: In response to the target SCG being the same as or different from the source SCG, the CHO configuration includes the RRC configuration of the target MCG and the RRC configuration of the target SCG, and wherein the RRC configuration of the target SCG is updated based on the RRC configuration of the source SCG.

11. The UE according to claim 10, wherein: In response to a change of a primary and secondary cell group cell (PSCell) of the source SCG or an update of an RRC configuration of the source SCG, the processor of the UE is configured to perform at least one of the following: continuing the CHO procedure on the target MCG; prohibiting application of the RRC configuration of the target SCG; Prohibit the execution of a random access RA procedure to the target SCG; or Transmitting third information to the target MCG via the transceiver, wherein the third information is associated with the change of the PSCell of the source SCG or the update of the RRC configuration of the source SCG. 12 . The UE according to claim 11 , wherein the third information is included in a radio resource control (RRC) reconfiguration complete message or a SCG failure information message.

13. The UE according to claim 10, wherein: In response to a change of a primary and secondary cell group cell PSCell of the source SCG or an update of an RRC configuration of the source SCG, the processor of the UE is configured to: performing the CHO procedure on the target MCG and the target SCG; applying an updated RRC configuration of the target SCG after the change of the PSCell of the source SCG or the update of the RRC configuration of the source SCG; and Fourth information is transmitted to the target MCG via the transceiver, wherein the fourth information is associated with the change of the PSCell of the source SCG or the update of the RRC configuration of the source SCG.

14. The UE according to claim 10, wherein the processor of the UE is configured to store the RRC configuration of the source SCG in response to reception of the CHO configuration or in response to the change of the PSCell of the source SCG or in response to the update of the RRC configuration of the source SCG.

15. A target master node MN, comprising: Transceiver; and a processor coupled to the transceiver, wherein the processor is configured to: receiving a handover request message from a source MN via the transceiver; transmitting, via the transceiver, a handover request confirmation message to the source MN, wherein the handover request confirmation message includes a conditional handover (CHO) configuration associated with a target secondary cell group (SCG) of a user equipment UE, and wherein the target SCG is the same as or different from a source SCG of the UE; and Failure related information is received from the UE via the transceiver.

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