Master node, secondary node and user equipment in mobile communication network and communication method thereof

Abstract

The invention discloses a main node, an auxiliary node and user equipment in a mobile communication network and a communication method thereof. According to one embodiment, a method performed by a master node (MN) in a mobile communication network comprises: sending a secondary node increase request message to a first target secondary node for requesting to change a secondary node connected to a user equipment (UE) from a source secondary node SN1 to a first target secondary node SN2; and receiving, from the UE, a first message regarding a secondary cell group (SCG) failure in a case where the UE fails to successfully connect to the first target secondary node (SN2).

Description

Technical Field

[0001] The present application relates to mobile communication technology, and in particular, to a master node, a secondary node, a user equipment and a communication method thereof for optimizing a secondary node wireless connection failure in a mobile communication network. Background Art

[0002] A user equipment UE can establish a wireless connection with one access node while establishing a wireless connection with another access node. The access node can be an eNB or a gNB. One of the nodes is a master node (hereinafter referred to as MN), and the other node is a secondary node (hereinafter referred to as SN).

[0003] Figure 1 1 is a schematic diagram of a UE establishing wireless connections with different access nodes at the same time, where the solid line represents the control plane and the dotted line represents the user plane. As shown in the figure, UE 110 establishes wireless connections with MN 120 and SN 130 at the same time, where MN 120 and SN 130 can communicate with core network 140 by wire. Figure 1 Under the wireless connection shown, MN 120 or SN 130 may decide to change the secondary node currently connected to UE 110 according to the situation. Figure 2 The diagram is a schematic diagram of changing the SN connected to the UE 110 , wherein the SN connected to the UE 110 is changed from SN 130 to SN 131 .

[0004] In the process of changing the SN, the UE may fail to connect to the new SN. For example, the UE 110 fails to connect to the changed SN 131. In this case, the MN may reselect an SN and configure it to the UE. The reselected SN may be the same as or different from the SN connected before the wireless connection failure occurs.

[0005] The decision to change the currently connected SN can be made by the MN or the currently connected SN. The MN or SN decides to select a new SN for the UE based on certain configuration parameters reaching certain values. For example, these parameters include the cell quality measurement results on the current SN, the cell quality measurement results on the surrounding adjacent SNs, etc. However, due to some reasons, such as these configuration parameters being set to inappropriate values, the MN or SN makes a bad timing to change the current SN, resulting in a network error. That is, before or after the process of changing the SN begins, the UE's wireless connection fails on the SN. In the existing mechanism, the MN or SN that makes the decision to change the SN lacks sufficient information to judge and adjust the configuration parameters used to change the SN in a timely manner, so it may still make a wrong decision to change the SN in the future, resulting in unnecessary wireless connection failures. Summary of the invention

[0006] Therefore, the present invention proposes a solution for optimizing the wireless connection failure of the auxiliary node in the mobile communication network. Through this solution, the relevant information of the wireless connection failure of the UE on the SN before and after the SN is changed can be sent to the MN or SN that makes the decision to change the SN. The MN or SN can judge whether the configuration parameters used to generate the changed SN are set to inappropriate values ​​based on this information and make correct adjustments. As a result, it avoids making an incorrect decision to change the SN in similar situations in the future, reduces unnecessary wireless connection failures of the UE on the SN, and improves the user experience.

[0007] According to one aspect, the present application provides a method performed by a master node MN in a mobile communication network, comprising: sending a secondary node add request message to a first target secondary node, requesting to change the secondary node connected to a user equipment UE from a source secondary node SN1 to a first target secondary node SN2; and in a case where the UE fails to successfully connect to the first target secondary node SN2, receiving a first message about the failure of a secondary cell group SCG from the UE.

[0008] In an embodiment, the first message may include at least one of the following information: the PSCell cell identifier of the primary and secondary cells of the first target secondary node SN2 where the SCG failure occurs, the cell quality measurement results of the PSCell cell and its adjacent cells of the first target secondary node SN2 where the SCG failure occurs, the PSCell cell identifier of the last secondary node to which the UE successfully connected, the time length between the SCG failure and the last successful secondary node change, and the UE identifier allocated to the UE by the source secondary node SN1, and the UE identifier allocated to the UE by the master node MN.

[0009] In an embodiment, the method may further include: when the UE successfully connects to the first target secondary node SN2, receiving a second message about the success of the secondary cell group SCG from the UE, the second message including configuration parameters and / or measurement results during the successful secondary cell change process.

[0010] In an embodiment, the method may further include: determining whether the triggering node for the SN change of the UE is the master node MN or the source secondary node SN1.

[0011] In an embodiment, the method may further include: determining, according to the first message, that a secondary node change of the UE fails, and judging a type of the secondary node change failure.

[0012] In an embodiment, the types of the secondary node change failure may include: changing to the first target secondary node SN2 at a too late timing, changing to the first target secondary node SN2 at a too early timing, and changing to a wrong secondary node.

[0013] In an embodiment, the method may further include: adjusting configuration parameters of the secondary node change according to the type of the secondary node change failure and the first message.

[0014] In an embodiment, the method may further include: before sending a secondary node add request message to the first target secondary node, receiving a secondary node change requirement message from the source secondary node SN1; after receiving a first message about the failure of the secondary cell group SCG from the UE, sending the first message to the source secondary node SN1.

[0015] In an embodiment, the method may also include: sending at least one of the following information to the source secondary node SN1: the PSCell cell identifier of the first target secondary node SN2 where the SCG failure occurs, the node ID of the first target secondary node SN2 where the SCG failure occurs, the PSCell cell identifier of the last secondary node to which the UE successfully connected, the node ID of the last secondary node to which the UE successfully connected, the PSCell cell identifier of the second target secondary node SN3 reselected by the master node MN for the UE, the node ID of the second target secondary node SN3 reselected by the master node MN for the UE, SN mobility information, and the UE identifier assigned by the source secondary node SN1 to the UE.

[0016] In an embodiment, the method may further include: sending the type of the secondary node change failure to the source secondary node SN1.

[0017] In an embodiment, the method may further include: sending at least one of the following information to the source secondary node SN1: the PSCell cell identifier of each secondary node to which the UE has been connected, the node ID of each secondary node to which the UE has been connected, the duration of the connection between the UE and each secondary node, and the reason for each secondary node change.

[0018] In an implementation manner, the master node MN may use an Xn message or an X2 message to send information to the source slave node SN1.

[0019] According to another aspect, the present application provides a method performed by a master node MN in a mobile communication network, comprising: receiving a first message from a UE about the failure of a secondary cell group SCG related to a source secondary node SN1; and sending a secondary node addition request message to a target secondary node, requesting that the secondary node connected to the UE be changed from the source secondary node SN1 to a target secondary node SN2.

[0020] In an embodiment, the method may further include: sending the first message to the source secondary node SN1.

[0021] In an embodiment, the first message may include at least one of the following information: the PSCell cell identifier of the primary and secondary cells of the source secondary node SN1 where the SCG failure occurs, the cell quality measurement results of the PSCell cell of the source secondary node SN1 where the SCG failure occurs and its adjacent cells, and the UE identifier allocated by the source secondary node SN1 to the UE, and the UE identifier allocated by the primary node to the UE.

[0022] In an embodiment, the method may further include: determining, according to the first message, that a secondary node change of the UE fails, and judging a type of the secondary node change failure.

[0023] In an embodiment, the type of the secondary node change failure is that the timing of changing to the target secondary node SN2 is too late.

[0024] In an embodiment, the method may further include: adjusting configuration parameters of the secondary node change according to the type of the secondary node change failure and the first message.

[0025] According to another aspect, the present application provides a method performed by a secondary node SN1 in a mobile communication network, comprising: requesting a master node MN to change a user equipment UE connected to the secondary node SN to be connected to a first target secondary node SN2; and receiving a first message about the failure of a secondary cell group SCG from the master node MN.

[0026] In an embodiment, the first message may include at least one of the following information: the PSCell cell identifier of the primary and secondary cells of the first target secondary node SN2 where the SCG failure occurs, the node ID of the first target secondary node SN2 where the SCG failure occurs, the PSCell cell identifier of the last secondary node to which the UE successfully connected, the node ID of the last secondary node to which the UE successfully connected, the PSCell cell identifier of the second target secondary node SN3 reselected by the master node MN for the UE, the node ID of the second target secondary node SN3 reselected by the master node MN for the UE, SN mobility information, the UE identifier assigned by the secondary node SN1 to the UE, and the type of secondary node change failure.

[0027] In an embodiment, the first message includes a second message received by the master node MN from the UE regarding the failure of the secondary cell group SCG, and the second message includes at least one of the following information: the PSCell cell identifier of the primary and secondary cells of the first target secondary node SN2 where the SCG failure occurs, the cell quality measurement results of the PSCell cell of the first target secondary node SN2 and its adjacent cells, the PSCell cell identifier of the last secondary node to which the UE successfully connected, the time length between the SCG failure and the last successful change of the secondary node, and the UE identifier allocated by the secondary node SN1 to the UE, and the UE identifier allocated by the master node MN to the UE.

[0028] In an embodiment, the method may further include: determining the type of secondary node change failure according to the first message, including changing to the first target secondary node SN2 too late, changing to the first target secondary node SN2 too early, and changing to a wrong secondary node.

[0029] In an embodiment, the method may further include: adjusting configuration parameters of the secondary node change according to the type of the secondary node change failure and the first message.

[0030] In an embodiment, when the UE successfully connects to the first target secondary node SN2, the first message may include a third message regarding the success of the secondary cell group SCG received by the master node MN from the UE, and the third message includes configuration parameters and / or measurement results during the successful secondary cell change process.

[0031] In an embodiment, the first message is an Xn message or an X2 message.

[0032] According to another aspect, the present application discloses a method performed by a secondary node SN1 in a mobile communication network, comprising: receiving a release request for releasing a connection with a UE from a primary node MN; sending a release response for releasing a connection with the UE to the primary node MN; and receiving a first message from the primary node.

[0033] In an embodiment, the first message may include at least one of the following information: the PSCell cell identifier of the primary and secondary cells of the secondary node where the SCG failure occurs, the node ID of the secondary node where the SCG failure occurs, the PSCell cell identifier of the last secondary node to which the UE successfully connected, the node ID of the last secondary node to which the UE successfully connected, the PSCell cell identifier of the target secondary node reselected by the master node MN for the UE, the node ID of the target secondary node reselected by the master node MN for the UE, SN mobility information, the UE identifier assigned by the secondary node SN1 to the UE, and the type of secondary node change failure.

[0034] In an embodiment, the first message includes a second message received by the master node MN from the UE regarding the failure of the secondary cell group SCG, the second message includes at least one of the following information: the primary and secondary cell PSCell cell identifiers of the secondary node where the SCG failure occurs, the cell quality measurement results of the PSCell cell of the secondary node where the SCG failure occurs and its adjacent cells, the PSCell cell identifier of the last secondary node to which the UE successfully connected, the length of time between the SCG failure and the last successful secondary node change, and the UE identifier assigned by the secondary node SN1 to the UE, and the UE identifier assigned by the master node to the UE. In an embodiment, the method may further include: determining the type of secondary node change failure according to the first message, the type of secondary node change failure including: changing to the secondary node where the SCG failure occurs too late, changing to the secondary node where the SCG failure occurs too early, and changing to an incorrect secondary node.

[0035] In an embodiment, the method may further include: adjusting configuration parameters of the secondary node change according to the type of the secondary node change failure and the first message.

[0036] In an embodiment, when the UE successfully connects to the target secondary node, the secondary node SN1 receives a second message about the success of the secondary cell group SCG from the primary node, and the second message includes configuration parameters and / or measurement results in the process of successful secondary cell change. At this time, the status of the SN change is a successful change, not a failed change.

[0037] In an embodiment, the first message is an Xn message or an X2 message.

[0038] According to another aspect, the present application discloses a method performed by a user equipment UE in a mobile communication network, including: determining that the connection has not been successfully changed from a source secondary node SN1 to a first target secondary node SN2 or has not been successfully connected to the source secondary node SN1; and sending a first message about the failure of a secondary cell group SCG to a master node MN.

[0039] In an embodiment, the first message may include at least one of the following information: the PSCell cell identifier of the primary and secondary cells of the secondary node where the SCG failure occurs, the cell quality measurement results of the PSCell cell of the secondary node where the SCG failure occurs and its adjacent cells, the PSCell cell identifier of the last secondary node to which the UE was successfully connected, the length of time between the SCG failure and the last successful change of the secondary node, the UE identifier allocated by the master node MN to the UE, and the UE identifier allocated by the source secondary node SN1 to the UE.

[0040] In an embodiment, the method may further include: reconnecting to the source secondary node SN1 or changing the connection to the second target secondary node SN3 according to the type of secondary node change failure determined by the master node MN.

[0041] In an embodiment, the method may further include: determining that the connection is successfully changed from the source secondary node SN1 to the first target secondary node SN2; and sending a second message about the success of the secondary cell group SCG to the master node MN, the second message including configuration parameters and / or measurement results during the successful secondary cell change process.

[0042] According to another aspect, the present application provides a method executed by a base station in a mobile communication network, including: receiving a wireless connection failure report; and after receiving the wireless connection failure report, sending the wireless connection failure report, user equipment UE historical information, and / or a mobile history information report reported by the UE to another base station through an interface between base stations or an interface between a base station and a core network node, wherein the mobile history information report includes the cell identification information of the secondary cell group SCG cell to which the UE has connected, and / or the length of time the UE has been connected to the cell.

[0043] The present application also provides a master node, a secondary node and a UE for executing the above method.

[0044] The present application also provides a computer-readable storage medium storing computer instructions for executing the above method. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a schematic diagram of a UE establishing wireless connections with different access nodes at the same time.

[0046] Figure 2 is a schematic diagram of changing the SN connected to UE 110.

[0047] Figure 3 This is a schematic diagram of Embodiment 1 of the present application.

[0048] Figure 4 This is a schematic diagram of the second embodiment of the present application.

[0049] Figure 5 This is a schematic diagram of Embodiment 3 of the present application.

[0050] Figure 6 This is a schematic diagram of Embodiment 4 of the present application.

[0051] Figure 7 This is a schematic diagram of Embodiment 5 of the present application.

[0052] Figure 8 This is a schematic diagram of Example 6 of the present application.

[0053] Fig. 9 This is a schematic diagram of Embodiment 7 of the present application.

[0054] Fig.10 This is a schematic diagram of Example 8 of the present application.

[0055] Fig.11 This is a schematic diagram of Embodiment 9 of the present application.

[0056] Fig.12 This is a schematic diagram of the tenth embodiment of the present application.

[0057] Fig.13 This is a schematic diagram of Example 11 of the present application.

[0058] Fig.14 This is a schematic diagram of the twelfth embodiment of the present application.

[0059] Fig.15 is a simplified block diagram of entities suitable for practicing embodiments of the present application. DETAILED DESCRIPTION

[0060] The present application is further described in detail below in conjunction with the accompanying drawings and examples. It should be understood that the specific examples described herein are only used to explain the relevant exemplary implementation schemes, rather than limiting the disclosure.

[0061] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0062] The terms used in this disclosure are used to describe specific embodiments and are not intended to limit the scope of other embodiments. The expression that does not explicitly indicate the quantity can generally be one or more, unless otherwise explicitly stated. All terms used herein, including technical and scientific terms, may have the same meaning as the terms commonly understood by those skilled in the art to which the disclosure belongs.

[0063] In the following description, a base station is an access device that accesses a communication device to a cellular network, and is used to allocate communication resources to the communication device. A base station may be any of the following entities: gNB, ng-eNB, eNB, radio access unit, base station controller, base transceiver station, and the like. A communication device may be any device that is intended to access services via an access network and can be configured for communication via an access network. For example, a communication device may include, but is not limited to, a user terminal UE, a mobile station MS, a cellular phone, a smart phone, a computer, or a multimedia system configured with a communication function. It should be noted that in the following description, the terms "communication device", "user equipment", "user terminal", "terminal" and "UE" may be used interchangeably.

[0064] It should be understood that the embodiments disclosed herein can be applied in various types of cellular networks.

[0065] The various embodiments of the present application may include a master node MN. The master node is a node that provides wireless connection services to the UE and connects to the core network. The master node may be a gNB or an eNB, or an ng-eNB. The various embodiments of the present application may also include a secondary node SN. The SN provides wireless connection services to the UE, has no control plane connection with the nodes of the core network, and may have a user plane connection. The SN may be a gNB or an eNB, or an ng-eNB, or an en-gNB.

[0066] According to the first embodiment of the present application, when the UE is connected to the MN and SN1 as the source secondary node at the same time, the MN changes the SN connected to the UE from SN1 to the first target secondary node SN2. In the case that the UE fails to successfully connect to SN2, the UE sends a report message about the failure of the secondary cell group (SCG) to the MN.

[0067] Optionally, the SCG failure report information received by the MN from the UE includes one or more of the following information: the cell identifier (Failed PSCellId) of the primary secondary cell (PSCell) to which the SN2 where the SCG failure occurs belongs; the measurement report of the PSCell cell and adjacent cells to which the SN2 where the SCG failure occurs belongs; the cell identifier (Previous PSCell Id) of the PSCell cell to which the last SN to which the UE successfully connected before the SN change belongs; the time length between the SCG failure and the last successful SN change; the UE identifier assigned by the SN, which may be a C-RNTI; and the UE identifier assigned by the MN.

[0068] Optionally, the master node determines the triggering node of the current SN change process and saves it for standby. The triggering node refers to the node that makes the decision to change the SN and initiates the SN change process. For example, the triggering node can be the master node MN or the source slave node SN1.

[0069] If the triggering node is the master node, that is, the current SN change process is initiated by the master node, then the master node can determine the SN change failure based on the received report information and determine the type of SN change failure. For example, the types of SN change failures may include: changing to SN2 too late, changing to SN2 too early, and changing to the wrong secondary node (SN change to wrong cell). Based on the received report information and the failure type determined based on the information, the master node can adjust the configuration parameters of the SN change. The adjusted configuration parameters can be used by the master node when it decides to change the SN next time to avoid similar SN change failures.

[0070] If the triggering node is the secondary node SN1 (i.e., the SN change process is determined by SN1) or the primary node cannot determine the triggering node, the primary node sends the SCG failure information to the secondary node. Optionally, the SCG failure information sent by the primary node to the secondary node SN1 includes one or more of the following information: the cell identifier (Failed PSCell Id) of the cell to which the secondary node SN2 to which the SCG failure occurs belongs; the measurement report of the cell and adjacent cells to which the secondary node SN2 to which the SCG failure occurs belongs; the cell identifier (Previous PSCell Id) of the cell to which the previous secondary node SN1 to which the UE successfully connected before the SN change belongs; the identifier (Serving PSCell Id) of the second target secondary node SN3 reselected by the primary node MN for the UE after the SCG failure, the SN mobility information, and the UE identifier assigned by the SN. The UE identifier can be a C-RNTI or an identifier assigned by the SN to the UE on the Xn or X2 interface (depending on the specific scenario). The SN mobility information is a digital identifier generated by SN1 (this information corresponds to a set of SN switching configuration parameters) and associated with the configuration parameters used to determine the SN change in SN1. SN1 can find the configuration parameters in SN1 used to determine the SN change based on this identifier. Optionally, before the SN change, SN1 can generate SN mobility information and send it to MN during the SN addition process or the SN change process. Optionally, the information sent by the master node to the slave node SN1 also includes: the node identifier (Failed SN ID) of the slave node SN2 where the SCG failure occurred, the node identifier (Previous SN ID) of the last slave node SN1 to which the UE successfully connected before the SN change, and the identifier (Serving SN ID) of the second target slave node SN3 reselected by the master node MN for the UE after the SCG failure. Optionally, the information sent by the master node to the secondary node SN1 also includes: a message about SCG failure received by the master node MN from the UE, the message including at least one of the following information: the PSCell cell identifier of the secondary node SN2 where the SCG failure occurs, the cell quality measurement results of the PSCell cell of the secondary node SN2 where the SCG failure occurs and its adjacent cells, the PSCell cell identifier of the last secondary node SN1 to which the UE successfully connected, the time length between the SCG failure and the last successful secondary node change, and the UE identifier assigned by the secondary node SN1 to the UE, and the UE identifier assigned by the master node MN to the UE. SN1 can determine the SN change failure based on the above information received, and determine the type of SN change failure.For example, the types of SN change failures may include: SN change too late, SN change too early, and SN change to wrong cell. According to the received report information and the failure type determined based thereon, SN1 may adjust the configuration parameters of the SN change. The adjusted configuration parameters may be used by SN1 the next time it decides to change the SN to avoid similar SN change failures.

[0071] Optionally, when the triggering node is the secondary node SN1 or the MN cannot determine the triggering node, the MN may also determine the SN change failure based on the received report information and determine the type of the SN change failure. In this case, the SCG failure information sent by the MN to the secondary node may also include the failure type of the SN failure determined by the primary node.

[0072] In the above process, each message sent between the MN and the SN may be an Xn message or an X2 message, and the message sent from the UE to the MN is an RRC message.

[0073] Optionally, the master node may use an Xn message to send SCG failure information to the slave node, and the Xn message may be a failure indication (FAILURE INDICATION), or a handover report (HANDOVER REPORT), or a UE context release (UECONTEXT RELEASE), or a slave node release request (S-NODE RELEASE REQUEST), or a newly defined Xn message, such as SN change failure information (SN CHANGE FAILURE INFORMATION). The master node may also use an X2 message to send SCG failure information to the slave node, and the X2 message may be a failure indication (RLF INDICATION), or a handover report (HANDOVER REPORT), or a UE context release (UE CONTEXT RELEASE), or a slave node release request (SGNBRELEASE REQUEST), or a newly defined X2 message, such as SN change failure information (SN CHANGE FAILURE INFORMATION).

[0074] Optionally, the report information of SCG failure received from the UE may be an EUTRAN RRC message SCGFailureInformation, or SCGFailureInformationNR; or it may be an NR RRC message SCGFailureInformation, or SCGFailureInformationEUTRA. Optionally, in the case of SCG success, the MN receives the report information of SCG success from the UE. The report information of SCG success received from the UE may be an NR RRC message SuccessfulSCGChangeReport or an EUTRAN RRC message SuccessfulSCGChangeReport.

[0075] Optionally, the master node sends at least one of the following information to the source secondary node SN1: the PSCell cell identifier of each secondary node connected to the UE, the node ID of each secondary node connected to the UE, the duration of the UE connection with each secondary node, and the reason for each secondary node change.

[0076] Optionally, when the UE successfully connects to the first target secondary node SN2, the UE sends a report message about the success of the secondary cell group SCG to the master node MN. Although the SN change is successful, it may not be smooth and encounter some errors in the process of successful SN change. Therefore, the information includes the configuration parameters and / or measurement results in the process of successful SN change, such as the UE's own configuration parameters and measurement results, which are usually some error information but no information that causes the failure of SN change. In the above process, although SCG failure did not occur, the above SN change has additional overhead. The above information can be used by the node initiating the SN change to adjust the parameter configuration information corresponding to the initiation of the SN change, so as to optimize the mechanism for deciding to initiate the SN change process, so as to avoid additional overhead in subsequent SN changes. Therefore, as an option, the master node judges the type of SCG failure based on the report message about SCG failure or SCG success received from the UE, which may also include SCG success but encountering errors in the success process.

[0077] According to the second embodiment, when the connection with the source secondary node SN1 fails, the UE sends a report message about the failure of the secondary cell group SCG to the master node MN. The report message includes, for example, at least one of the following information: the PSCell Id cell identifier of the source secondary node SN1 where the SCG failure occurs, the cell quality measurement results of the cell of the source secondary node SN1 where the SCG failure occurs and its adjacent cells, and the UE identifier assigned by the SN. The identifier may be a C-RNTI, and the UE identifier assigned by the MN, and the identifier may be a C-RNTI. Optionally, the MN sends the received report information to SN1.

[0078] Optionally, the master node MN determines that the UE's secondary node switching fails according to the received report message, and determines that the type of the secondary node switching failure is that the timing of changing to SN2 is too late (SN change too late), and connects the UE to the first target secondary node SN2 according to the determined failure type and the report message. According to the determined type of SN switching failure and the report, the MN adjusts the configuration parameters of the secondary node switching.

[0079] Hereinafter, the above-mentioned embodiments will be exemplarily described through examples.

[0080] Example 1 describes the situation in the first implementation mode where the SN decides to initiate the SN change process, and a secondary cell group failure (SCG failure) occurs shortly after the success, or an SCG failure occurs during the SN change process.

[0081] Figure 3 This is a schematic diagram of Embodiment 1 of the present application, comprising the following steps:

[0082] Step 301: The second node MN sends a message 1 to the third node SN1.

[0083] Step 302: The third node SN1 sends a message 2 to the second node MN. The message 2 may carry associated information of configuration parameters used by the third node SN1 to determine SN change, that is, the SN mobility information mentioned above.

[0084] Step 303: The third node SN1 sends a message 3 to the second node MN. The message 3 may also carry associated information of configuration parameters used by the third node SN1 to determine the SN change.

[0085] Step 304: The second node MN sends a message 4 to the fourth node SN2. The message 4 may carry information about the SNs to which the UE has been connected.

[0086] Step 305: The fourth node SN2 sends a message 5 to the second node MN.

[0087] Step 306: The second node MN sends a message 6 to the third node SN1.

[0088] Step 307: The second node MN sends a message 7 to the third node SN1.

[0089] Step 308: The first node UE sends a message 8 to the second node MN. The message 8 may carry the identification information of the last successfully connected SN, and / or the identification information of the SN where the SCG failure occurred, and / or the duration between the last successful SN change event and the SCG failure event, and / or the UE identification assigned by the SN to the UE, and / or the UE identification assigned by the MN to the UE. The UE identification may be a C-RNTI. The SN identification information includes the PSCell ID of the cell to which the SN belongs.

[0090] Step 309: The second node MN sends a message 9 to the third node SN1. The message 9 may carry the associated information of the configuration parameters used to determine the SN change carried in step 302 or 303. The message 9 may carry the identification information of the last successfully connected SN, and / or the identification information of the SN where the SCG failure occurred, and / or the identification information of the SN to which the UE is currently connected. The SN identification information includes the PSCell ID of the cell to which the SN belongs, and optionally, may also include the node ID of the SN.

[0091] If the second node SN1 has not sent message 7 when receiving message 8, message 7 may be the same as message 9.

[0092] The following will refer to Figure 6 and Figure 7 The specific scenario of the first embodiment is described exemplarily.

[0093] Embodiment 2 describes the situation in the first embodiment where the MN decides to initiate the SN change process, and SCG failure occurs shortly after the process succeeds.

[0094] Figure 4 This is a schematic diagram of Embodiment 2 of the present application, comprising the following steps (wherein, Figure 3 The same message number indicates the same or similar messages):

[0095] Step 401: The second node MN sends a message 1 to the third node SN1.

[0096] Step 402: The third node SN1 sends a message 2 to the second node MN. The message 2 may carry associated information of configuration parameters used by the third node SN1 to determine SN change.

[0097] Step 403: The second node MN sends a message 4 to the fourth node SN2. The message 4 may carry information about the SNs to which the UE has been connected.

[0098] Step 404: The fourth node SN2 sends a message 5 to the second node MN.

[0099] Step 405: The second node MN sends a message 10 to the third node SN1.

[0100] Step 406: The third node SN1 sends a message 11 to the second node MN.

[0101] Step 407: The second node MN sends a message 7 to the third node SN1.

[0102] Step 408: The first node UE sends a message 8 to the second node MN. The message 8 may carry the identification information of the last successfully connected SN, and / or the identification information of the SN where the SCG failure occurred, and / or the duration between the last successful SN change event and the SCG failure event, and / or the UE identification assigned by the SN to the UE, and / or the UE identification assigned by the MN to the UE. The UE identification may be a C-RNTI. The SN identification information includes the PSCell ID of the cell to which the SN belongs.

[0103] The following will refer to Figure 8 and Fig. 9 The specific scenario of the second embodiment is described exemplarily.

[0104] Embodiment 3 describes the situation in the second implementation mode where the UE has been connected to the SN, and after an SCG failure occurs, the MN configures a new SN for the UE.

[0105] Figure 5 This is a schematic diagram of Embodiment 3 of the present application, comprising the following steps (wherein, Figure 3 The same message number indicates the same or similar messages):

[0106] Step 501: The first node UE sends a message 8 to the second node MN. The message 8 carries the identification information of the SN where the SCG failure occurs. The SN identification information includes the PSCell ID of the cell to which the SN belongs.

[0107] Step 502: The second node MN sends a message 4 to the fourth node SN2.

[0108] Step 503: The fourth node SN2 sends a message 5 to the second node MN.

[0109] Step 504: The second node MN sends a message 7 to the third node SN1. The message 7 may carry the identification information of the SN to which the UE is currently connected. The SN identification information includes the PSCell ID of the cell to which the SN belongs, and optionally, may also include the node ID of the SN.

[0110] The following will refer to Fig.10 and Fig.11 The specific scenario of the second embodiment is described exemplarily.

[0111] Figure 6 This is a schematic diagram of Embodiment 4 of the present application. Embodiment 4 is the following specific scenario of Embodiment 1: The UE is connected to the MN. The UE is configured to add a secondary node SN1. SN1 decides to initiate an SN change process and change the secondary node to SN2. Shortly after the success, the UE's SCG failure on SN2 occurs, or an SCG failure occurs during the SN change process. The UE is configured to add a secondary node SN3. The MN is a gNB. The SN1, SN2, and SN3 can be gNBs or ng-eNBs.

[0112] Figure 6 The fourth embodiment shown includes the following steps:

[0113] Step 601: MN sends an Xn signaling S-NODE ADDITION REQUEST to SN1, requesting SN1 to configure resources for the UE. The signaling carries the PDU session information that needs to be configured on SN1, such as the identifier of the PDU session, the identifier of the QoS flow included in the session, and the quality requirement of the QoS flow. The signaling may also carry SCG configuration information, which contains the capability information of the UE.

[0114] Step 602: After receiving the signaling in the previous step, SN1 allocates resources according to the signaling requirements. SN1 sends an Xn signaling secondary node addition response (S-NODE ADDITION REQUEST ACKNOWLEDGE) to MN to inform MN of the accepted PDU session information. The signaling can carry the new SCG configuration information provided by SN1, which is sent to MN through an RRC container, and MN sends the SCG configuration information to the UE through an RRC message. The signaling can also carry information SN mobility information (SNMobility Information). SN mobility information is generated by SN1, which corresponds to a set of SN switching configuration parameters and is a digital identifier associated with the configuration parameters used to determine the SN change. SN provides this information to MN for later analysis of the cause of the erroneous SN switching. For example, SN sends this information to MN, and MN saves this information. If MN receives a message of SN failure reported by UE, MN can send this information to SN, and SN can determine which parameter / parameters need to be adjusted based on the report information of UE and the configuration information corresponding to SN MobilityInformation. The MN adds the information of SN1 to the UE History Information saved by the MN as the information of the SN to which the UE is currently connected. The information of SN1 may be the SN identification information of SN1, and / or the duration of the UE's connection to the SN, and / or the reason why the UE's SN is configured as SN1. The identification information of the SN includes the PSCell ID, and optionally, may also include the node ID. Optionally, the MN may save the above SN1 information as a separate information part instead of adding it to the UE History Information.

[0115] SN1 receives a measurement report from the UE, which may be forwarded to SN1 by the MN, or SN1 directly receives the measurement report from the UE. SN1 decides to initiate an SN change procedure to change the SN of the UE from SN1 to SN2.

[0116] Step 603: SN1 sends an Xn signaling S-NODE CHANGE REQUIRED to MN, notifying MN to change the SN of the UE to SN2. The information carries the node identifier of SN2 and may also carry the latest SCG configuration information. The signaling may also carry the field information SN Mobility Information. The purpose of this information is as shown in step 602, indicating a set of configuration information related to SN switching. MN determines that this SN change process is triggered by SN1 and saves this information.

[0117] Step 604: MN sends an Xn signaling secondary node addition request (S-NODE ADDITION REQUEST) to SN2, requesting SN2 to configure resources for the UE.

[0118] Step 605: After receiving the signaling in step 604, SN2 allocates resources according to the signaling requirements. SN2 sends an Xn signaling secondary node addition response (S-NODE ADDITION REQUEST ACKNOWLEDGE) to MN.

[0119] The MN adds the information of SN2 to the UE History Information saved by the MN as the information of the SN to which the UE is currently connected. The information of SN2 may be the SN identification information of SN2, and / or the duration of the UE's connection to the SN, and / or the reason why the UE's SN is configured as SN2. The identification information of the SN includes the PSCell ID, and optionally, may also include the node ID. Optionally, the MN may save the above SN2 information as a separate information part instead of adding it to the UE History Information.

[0120] Step 606: MN sends an Xn signaling S-NODE CHANGE CONFIRM to SN1. After receiving the signaling, SN1 stops sending data to the UE. Step 607: MN sends an Xn signaling UE CONTEXT RELEASE to SN1. After receiving the signaling, SN1 releases the UE context and its associated resources.

[0121] Within a short period of time after the SN change process is successful, the UE experiences an SCG failure on SN2. Or an SCG failure occurs during the SN change process.

[0122] Step 608: The UE sends an NR RRC message secondary cell group failure information (SCGFailureInformation) to the MN.

[0123] The UE detects that the SCG fails, and reports the SCG failure message to the MN.

[0124] If the SCG failure occurs after the SN change is successful, the message SCGFailureInformation may carry the identification information of the PSCell to which the SN to which the UE successfully connected before the SN change belongs (Previous PSCell ID), and / or the identification information of the PSCell to which the SN to which the SCG failure occurs belongs (Failed PSCell ID), and / or the duration between the last successful SN change event and the SCG failure event (timeSCGChangeFailure). If SN2 is an ng-eNB, the UE sends the NR RRC message EUTRA secondary cell group failure information (SCGFailureInformationEUTRA) to the MN. The message may carry the identification information of the PSCell to which the SN to which the UE successfully connected before the SN change belongs (Previous PSCell ID), and / or the identification information of the PSCell to which the SN to which the SCG failure occurs (Failed PSCell ID), and / or the duration between the last successful SN change event and the SCG failure event (timeSCGChangeFailure), and / or the UE identifier assigned by the SN to the UE, and / or the UE identifier assigned by the MN to the UE. The UE identifier may be a C-RNTI.

[0125] If the SCG failure occurs during the SN change process, the message SCGFailureInformation may carry the identification information (Previous PSCell ID) of the PSCell to which the SN to which the UE successfully connected before the SN change belongs, and / or the identification information (Failed PSCell ID) of the PSCell to which the SN where the SCG failure occurred belongs. The value of the subfield failureType of the field FailureReportSCG carried by the message may be set to scg-ChangeFailure. If SN2 is ng-eNB, the UE sends an NR RRC message SCGFailureInformationEUTRA to the MN. The message may carry the identification information (Previous PSCell ID) of the PSCell to which the SN to which the UE successfully connected before the SN change belongs, and / or the identification information (Failed PSCell ID) of the PSCell to which the SN where the SCG failure occurred.

[0126] MN updates the duration of the UE connection to the SN in the information of SN2 in the UE history message saved by MN according to the time when the SN to which the UE is currently connected in the UE history message saved by MN is set to SN2 and the time when MN receives the SCG failure message sent by UE.

[0127] After step 608, the MN may send a secondary node release request message to notify SN2 to release the UE context.

[0128] The MN may determine the cause / type of the SN change failure based on the information received in step 608 and the information stored by the MN.

[0129] -Specifically, the MN determines that the SN to which the UE was connected before the SN change was SN1 based on the Previous PSCell ID contained in the RRC message received from the UE, and determines that the SN where the SCG failure occurred was SN2 based on the Failed PSCell ID contained in the RRC message. The MN selects a new SN for the UE based on the measurement report carried in the message in which the UE reports the SCG failure. In this embodiment, the new SN is SN3. One of the following two conditions is met: the message in which the UE reports the SCG failure carries timeSCGChangeFailure, and the value is lower than a pre-configured threshold; or, the message in which the UE reports the SCG failure does not carry timeSCGChangeFailure, or the value of failureType in the message is scg-ChangeFailure. Based on the above information, the MN determines that the type of this SN change failure is a change to an incorrect secondary node (SNChange to wrong cell).

[0130] -Or, the MN determines that the SN to which the UE was connected before the SN change was SN1 based on the information of the SN before the SN currently connected to the UE in the stored UE history information, and determines that the SN where the SCG failure occurred was SN2 based on the information of the SN currently connected to the UE in the stored UE history information. The MN selects a new SN for the UE based on the measurement report carried in the message in which the UE reports the SCG failure. In this embodiment, the new SN is SN3. And the duration of the UE's connection to the SN in the information of SN2 in the UE history message stored by the MN is lower than a pre-configured threshold. Based on the above information, the MN determines that the type of this SN change failure is a change to a wrong secondary node (SN Change to wrong cell).

[0131] Step 609: MN sends an Xn signaling secondary node addition request (S-NODE ADDITION REQUEST) to SN3.

[0132] The MN receives the report message of the SCG failure, selects a new secondary node SN for the UE according to the measurement report sent by the UE, and sends a secondary node establishment request message to the new secondary node SN. The signaling may carry one or more of the following information:

[0133] -UE History Information, where the UE History Information may include the identification information of the SNs to which the UE has been connected, and / or the duration for which the UE has been connected to the SN, and / or the reason for changing the SN.

[0134] -SN information, the SN information includes the identification information of the SN to which the UE has been connected, and / or the duration for which the UE has been connected to the SN, and / or the reason for changing the SN.

[0135] The SN identification information includes a PSCell ID and, optionally, a node ID.

[0136] Step 610: SN3 sends an Xn signaling secondary node addition response (S-NODE ADDITION REQUESTACKNOWLEDGE) to MN. MN adds the information of SN3 to the UE History Information saved by MN as the information of the SN to which the UE is currently connected. The information of SN3 may be the SN identification information of SN3, and / or the duration of the UE's connection to the SN, and / or the reason why the UE's SN is configured as SN3. The identification information of the SN includes the PSCell ID, and optionally, may also include the node ID. Optionally, MN may save the above-mentioned SN3 information as a separate information part instead of adding it to the UE History Information.

[0137] According to the above-mentioned stored information, MN can know that this SN change process is triggered by SN1. Therefore, MN notifies SN1 of the relevant information of the SCG failure.

[0138] Step 611: MN sends Xn signaling to SN1 to notify SN of failure information. The signaling may be a failure indication (Failure Indication), or an Xn signaling handover report (Handover Report), or a newly defined signaling.

[0139] Step 611 may be performed at any time after step 608 .

[0140] If step 607 has not been executed when step 611 needs to be executed, the signaling may also be an Xn signaling UE CONTEXT RELEASE request.

[0141] The signaling may include one or more of the following information:

[0142] - Information carried in step 602 or 603: SN Mobility Information.

[0143] - may include the identification information of the SN to which the UE successfully connected before the SN change (Previous SN Information),

[0144] - Failed SN Information,

[0145] - After the UE reports the SCG failure, the identification information of the SN that the MN reconfigured to the UE and to which the UE successfully connected (Serving SNInformation).

[0146] The SN identification information mentioned above includes a PSCell ID, and optionally, may also include a node ID.

[0147] - The RRC message secondary cell group failure information received in step 608.

[0148] - The field information SCG Failure Type indicating the type of SN change failure determined by the MN. The SCG Failure Type may be SN change too late, SN change too early, and SN change to wrong cell. For example, if the MN determines that the type of SN change failure is SN change to wrong cell, the SCG Failure Type may be SN change to wrong cell.

[0149] -UE History Information, where the UE History Information may include SN information, such as identification information of the SNs to which the UE has been connected, and / or the duration of the UE's connection to the SN, and / or the reason for changing the SN.

[0150] - Separate SN information (SN information), the SN information includes the identification information of the SN to which the UE has been connected, and / or the duration of the UE's connection to the SN, and / or the reason for changing the SN.

[0151] - An indication of whether the SCG failure occurred during or after the SN change process. The indication may also be the type of SCG error, such as an SCG radio connection error, or an SCG change error.

[0152] After receiving the signaling of step 611, if the signaling does not include the field information SCG Failure Type indicating the SCG failure type, SN1 can determine the type of SN change failure based on the above information.

[0153] - Specifically, if the Previous SN Information field includes the identification information of SN1 and is different from the Failed SN Information field and the Serving SN Information field, and one of the following two conditions is met:

[0154] -The message reporting SCG failure by the UE carries timeSCGChangeFailure, and the value is lower than the pre-configured threshold;

[0155] - The message in which the UE reports the SCG failure does not carry timeSCGChangeFailure, or the value of failureType in the message is scg-ChangeFailure

[0156] -Or, SN1 determines that the SN to which the UE is connected before the SN change is SN1 based on the received UE history information or SN information, and determines that the SN to which the SCG failure occurs is SN2 based on the information of the SN before the SN to which the UE is currently connected in the received UE history information or SN information, and determines that the SN to which the UE is currently connected is SN3 based on the information of the SN to which the UE is currently connected in the received UE history information or SN information. And the duration of the UE's connection to the SN in the information of SN2 in the UE history information or SN information received by SN1 is lower than a pre-configured threshold.

[0157] SN1 uses SN Mobility Information to associate with the configuration parameters used by SN1 to determine the SN change. Based on the above information, SN1 determines that the type of this SN change failure is SN Change to wrong cell.

[0158] If the signaling includes information SCG Failure Type indicating the SCG failure type, then SN1 can use this as its own judgment, or it can judge the type of SN change failure by itself according to the above method.

[0159] SN1 can determine the reason for the SN change failure based on the above information, adjust the parameter configuration information corresponding to initiating the SN change according to the reason, and optimize the mechanism for deciding to initiate the SN change process.

[0160] Figure 7 This is a schematic diagram of Embodiment 5 of the present application. Embodiment 5 is the following specific scenario of Embodiment 1: The UE is connected to the MN. The UE is configured to add a secondary node SN1. SN1 decides to initiate an SN change process and changes the secondary node to SN2. Shortly after the success, the SCG failure of the UE on SN2 occurs, or the SCG failure occurs during the SN change process. The UE is configured to add a secondary node SN3. The MN is an eNB, and SN1, SN2, and SN3 can be en-gNB or eNB.

[0161] Figure 7 The fifth embodiment shown includes the following steps:

[0162] Step 701: MN sends an X2 signaling secondary node addition request (SGNB ADDITION REQUEST) to SN1, requesting SN1 to configure resources for the UE. The signaling carries the evolved radio bearer (E-RAB) information that needs to be configured on SN1, such as the E-RAB identifier and the quality requirements of the E-RAB. The signaling may also carry SCG configuration information, which includes the capability information of the UE.

[0163] Step 702: After receiving the signaling in the previous step, SN1 allocates resources according to the signaling requirements. SN1 sends an X2 signaling secondary node addition response (SGNB ADDITION REQUEST ACKNOWLEDGE) to MN to inform MN of the accepted evolved radio bearer (E-RAB) information. The signaling can carry the new SCG configuration information provided by SN1, which is sent to MN through an RRC container, and MN sends the SCG configuration information to the UE through an RRC message. The signaling can also carry field information SN Mobility Information. The information is generated by SN1, which corresponds to a set of SN switching configuration parameters and is a digital identifier associated with the configuration parameters used to determine the SN change. SN provides the information to MN for later analysis of the cause of the erroneous SN switching. For example, SN sends the information to MN, and MN saves the information. If MN receives a message of SN failure reported by the UE, MN can send the information to SN, and SN can determine which parameter / parameters need to be adjusted based on the report information of the UE and the configuration information corresponding to the SN MobilityInformation. The MN adds the information of SN1 to the UE History Information saved by the MN as the information of the SN to which the UE is currently connected. The information of SN1 may be the SN identification information of SN1, and / or the duration of the UE's connection to the SN, and / or the reason why the UE's SN is configured as SN1. The identification information of the SN includes the PSCell ID, and optionally, may also include the node ID. Optionally, the MN may save the above SN1 information as a separate information part instead of adding it to the UE History Information.

[0164] Step 703: SN1 sends an X2 signaling secondary node change request (SGNB CHANGE REQUIRED) to MN, notifying MN to change the SN of the UE to SN2. The information carries the node identification information of SN2 and may also carry new SCG configuration information. The signaling may also carry field information SN Mobility Information. The purpose of this information is as shown in step 702, indicating a group of configuration information related to SN switching. MN determines that this SN change process is triggered by SN1 and saves this information.

[0165] Step 704: The MN sends an X2 signaling secondary node addition request (SGNB ADDITION REQUEST) to SN2, requesting SN2 to configure resources for the UE.

[0166] Step 705: After receiving the signaling in the previous step, SN2 allocates resources according to the signaling request. SN2 sends an X2 signaling secondary node addition response (SGNB ADDITION REQUEST ACKNOWLEDGE) to MN.

[0167] The MN adds the information of SN2 to the UE History Information saved by the MN as the information of the SN to which the UE is currently connected. The information of SN2 may be the SN identification information of SN2, and / or the duration of the UE's connection to the SN, and / or the reason why the UE's SN is configured as SN2. The identification information of the SN includes the PSCell ID, and optionally, may also include the node ID. Optionally, the MN may save the above SN2 information as a separate information part instead of adding it to the UE History Information.

[0168] Step 706: MN sends an X2 signaling SGNB CHANGE CONFIRM to SN1. After receiving the signaling, SN1 stops sending data to the UE.

[0169] Step 707: MN sends an X2 signaling UE CONTEXT RELEASE to SN1. After receiving the signaling, SN1 releases the UE context and its associated resources.

[0170] Within a short period of time after the SN change process is successful, the UE experiences an SCG failure on SN2. Or an SCG failure occurs during the SN change process.

[0171] Step 708: The UE sends an EUTRAN RRC message NR secondary cell group failure information (SCGFailureInformationNR) to the MN.

[0172] The UE detects that the SCG fails, and reports the SCG failure message to the MN.

[0173] If the SCG failure occurs after the SN change is successful, the message SCGFailureInformationNR may carry the identification information of the PSCell to which the SN to which the UE successfully connected before the SN change belongs (Previous PSCell ID), and / or the identification information of the PSCell to which the SN to which the SCG failure occurs belongs (Failed PSCell ID), and / or the duration between the last successful SN change event and the SCG failure event (timeSCGChangeFailure). If SN2 is an eNB, the UE sends an EUTRAN RRC message secondary cell group failure information (SCGFailureInformation) to the MN. The message may carry the identification information of the PSCell to which the SN to which the UE successfully connected before the SN change belongs (Previous PSCell ID), and / or the identification information of the PSCell to which the SN to which the SCG failure occurs (Failed PSCell ID), and / or the duration between the last successful SN change event and the SCG failure event (timeSCGChangeFailure).

[0174] If SCG failure occurs during the SN change process, the message SCGFailureInformationNR may carry the identification information (Previous PSCell ID) of the PSCell to which the SN to which the UE successfully connected before the SN change belongs, and / or the identification information (Failed PSCell ID) of the PSCell to which the SN where the SCG failure occurred belongs. The value of the subfield failureType-r15 of the field FailureReportSCG-NR-r15 carried by the message may be set to scg-ChangeFailure. If SN2 is an eNB, the UE sends an EUTRAN RRC message SCGFailureInformation to the MN. The message may carry the identification information (Previous PSCell ID) of the PSCell to which the SN to which the UE successfully connected before the SN change belongs, and / or the identification information (Failed PSCell ID) of the PSCell to which the SN where the SCG failure occurred belongs.

[0175] MN updates the duration of the UE connection to the SN in the information of SN2 in the UE history message saved by MN according to the time when the SN to which the UE is currently connected in the UE history message saved by MN is set to SN2 and the time when MN receives the SCG failure message sent by UE.

[0176] After step 708, the MN may send a secondary node release request message to notify SN2 to release the UE context.

[0177] The MN can determine the cause / type of the SN change failure based on the information received in step 708 and the information stored by the MN. The method is described in the fourth embodiment.

[0178] Step 709: MN sends an X2 signaling secondary node addition request (SGNB ADDITION REQUEST) to SN3.

[0179] The MN receives the report message of SCG failure, selects a new SN for the UE according to the measurement report sent by the UE, and sends a secondary node establishment request message to the new SN. The signaling may carry one or more of the following information:

[0180] -UE History Information, where the UE History Information may include the identification information of the SNs to which the UE has been connected, and / or the duration for which the UE has been connected to the SN, and / or the reason for changing the SN.

[0181] -SN information, the SN information includes the identification information of the SN to which the UE has been connected, and / or the duration for which the UE has been connected to the SN, and / or the reason for changing the SN.

[0182] The SN identification information includes the PSCell ID of the cell to which the SN belongs, and optionally, may also include the node ID of the SN.

[0183] Step 710: SN3 sends an X2 signaling secondary node addition response (SGNB ADDITION REQUESTACKNOWLEDGE) to MN. MN adds the information of SN3 to the UE History Information saved by MN as the information of the SN to which the UE is currently connected. The information of SN3 may be the SN identification information of SN3, and / or the duration of the UE's connection to the SN, and / or the reason why the UE's SN is configured as SN3. The identification information of the SN includes the PSCell ID, and optionally, may also include the node ID. Optionally, MN may save the above-mentioned SN3 information as a separate information part instead of adding it to the UE History Information.

[0184] According to the above-mentioned stored information, MN can know that this SN change process is triggered by SN1. Therefore, MN notifies SN1 of the relevant information of the SCG failure.

[0185] Step 711: MN sends X2 signaling to SN1 to notify SN of failure information. The signaling may be X2 signaling radio connection failure indication (RLF INDICATION), or X2 signaling handover report (HANDOVER REPORT), or a newly defined signaling.

[0186] Step 711 may be executed at any time after step 708 .

[0187] If step 707 has not been executed when step 711 needs to be executed, the signaling may also be X2 signaling UE CONTEXT RELEASE.

[0188] The signaling may include one or more of the following information:

[0189] -Field information carried in step 702 or 703: SN Mobility Information.

[0190] - The identification information of the SN to which the UE successfully connected before the SN change (Previous SN Information),

[0191] - Failed SN Information,

[0192] -After the UE reports the SCG failure, the MN reconfigures the UE and the SN identification information (Serving SNInformation) to which the UE successfully connects.

[0193] The above-mentioned SN identification information includes the PSCell ID of the cell to which the SN belongs, and optionally, may also include the node ID of the SN.

[0194] -RRC message NR secondary cell group failure information received in step 708.

[0195] - Information SCG Failure Type, indicating the type of SN change failure determined by the MN. The SCG Failure Type may be SN change too late, SN change too early, and SN change to wrong cell. For example, if the MN determines that the type of SN change failure is SN change to wrong cell, the SCG Failure Type may be SN change to wrong cell.

[0196] -UE History Information, where the UE History Information may include SN information, such as identification information of the SNs to which the UE has been connected, and / or the duration of the UE's connection to the SN, and / or the reason for changing the SN.

[0197] - Separate SN information (SN information), the SN information includes the identification information of the SN to which the UE has been connected, and / or the duration of the UE's connection to the SN, and / or the reason for changing the SN.

[0198] - An indication of whether the SCG failure occurred during or after the SN change process. The indication may also be the type of SCG error, such as an SCG radio connection error, or an SCG change error.

[0199] After receiving the signaling of step 711, if the signaling does not include the field information SCG Failure Type indicating the SCG failure type, SN1 can determine the type of SN change failure according to the above information. The method is described in the fourth embodiment.

[0200] If the signaling includes information SCG Failure Type indicating the SCG failure type, SN1 can use this as its own judgment, or it can judge the type of SN change failure by itself according to the above method.

[0201] SN1 can determine the reason for the SN change failure based on the above information, adjust the parameter configuration information corresponding to initiating the SN change according to the reason, and optimize the mechanism for deciding to initiate the SN change process.

[0202] Figure 8 This is a schematic diagram of Embodiment 6 of the present application. Embodiment 6 is the following specific scenario of Embodiment 2: UE is connected to MN. UE is configured to add a secondary node SN1. MN decides to initiate an SN change process and change the secondary node to SN2. SCG failure of UE on SN2 occurs shortly after the SN change is successful, or SCG failure occurs during the SN change process. UE is configured to add a secondary node SN3. MN, SN1, SN2 and SN3 are all gNBs.

[0203] Figure 8 The sixth embodiment shown includes the following steps:

[0204] Step 801: MN sends an Xn signaling S-NODE ADDITION REQUEST to SN1, requesting SN1 to configure resources for UE. The signaling carries PDU session information that needs to be configured on SN1, and may also carry SCG configuration information.

[0205] Step 802: After receiving the signaling in the previous step, SN1 allocates resources according to the signaling requirements. SN1 sends an Xn signaling secondary node addition response (S-NODE ADDITION REQUEST ACKNOWLEDGE) to MN to inform MN of the accepted PDU session information. The signaling may carry the new SCG configuration information provided by SN1. MN adds the SN1 information to the UE History Information saved by MN as the information of the SN to which the UE is currently connected. The SN1 information may be the SN identification information of SN1, and / or the length of time the UE is connected to the SN, and / or the reason why the UE's SN is configured as SN1. The identification information of the SN includes the PSCell ID, and optionally, may also include the node ID. Optionally, MN may save the above SN1 information as a separate information portion instead of adding it to the UE history information.

[0206] MN decides to initiate the SN change process to change the SN of the UE from SN1 to SN2. This SN change process is triggered by MN, and MN saves this information.

[0207] Step 803: MN sends an Xn signaling secondary node addition request (S-NODE ADDITION REQUEST) to SN2.

[0208] Step 804: SN2 sends an Xn signaling secondary node addition response (S-NODE ADDITION REQUESTACKNOWLEDGE) to MN. MN adds the information of SN2 to the UE History Information saved by MN as the information of the SN to which the UE is currently connected. The information of SN2 may be the SN identification information of SN2, and / or the duration of the UE's connection to the SN, and / or the reason why the UE's SN is configured as SN2. The identification information of the SN includes the PSCell ID, and optionally, may also include the node ID. Optionally, MN may save the above-mentioned SN2 information as a separate information part instead of adding it to the UE History Information.

[0209] Step 805: MN sends an Xn signaling S-NODE RELEASE REQUEST to SN1 to notify SN1 to release UE-related resources.

[0210] Step 806: After receiving the signaling in the previous step, SN1 stops sending data to the UE. SN1 sends an Xn signaling secondary node release response (S-NODE RELEASE REQUEST ACKNOWLEDGE) to the MN.

[0211] Step 807: MN sends Xn signaling UE CONTEXT RELEASE to SN1. After receiving the signaling, SN1 releases the UE context and its associated resources.

[0212] Within a short period of time after the SN change process is successful, the UE experiences an SCG failure on SN2. Or an SCG failure occurs during the SN change process.

[0213] Step 808: The UE sends an NR RRC message secondary cell group failure information (SCGFailureInformation) to the MN.

[0214] The UE detects that the SCG fails, and reports the SCG failure message to the MN.

[0215] If the SCG failure occurs after the SN change is successful, the message SCGFailureInformation may carry the identification information (Previous PSCell ID) of the PSCell to which the SN to which the UE was successfully connected before the SN change, and / or the identification information (Failed PSCell ID) of the PSCell to which the SN where the SCG failure occurred belongs, and / or the duration (timeSCGChangeFailure) between the last successful SN change event and the SCG failure event.

[0216] If the SCG failure occurs during the SN change process, the message SCGFailureInformation may carry the identification information (Previous PSCell ID) of the PSCell to which the SN to which the UE successfully connected before the SN change belongs, and / or the identification information (Failed PSCell ID) of the PSCell to which the SN where the SCG failure occurred belongs. The value of the subfield failureType of the field FailureReportSCG carried by the message may be set to scg-ChangeFailure.

[0217] MN updates the duration of the UE connection to the SN in the information of SN2 in the UE history message saved by MN according to the time when the SN to which the UE is currently connected in the UE history message saved by MN is set to SN2 and the time when MN receives the SCG failure message sent by UE.

[0218] The MN can determine the type of SN change failure based on the above information.

[0219] -Specifically, the MN determines, based on the Previous PSCell ID and the Failed PSCell ID, that the SN to which the UE was connected before the SN change was SN1, and that the SN where the SCG failure occurred was SN2. The MN selects a new SN for the UE based on the measurement report carried in the message in which the UE reports the SCG failure. In this embodiment, the new SN is SN3. One of the following two conditions is met: the message in which the UE reports the SCG failure carries timeSCGChangeFailure, and the value is lower than a pre-configured threshold; the message in which the UE reports the SCG failure does not carry timeSCGChangeFailure, or the value of failureType in the message is scg-ChangeFailure. Based on the above information, the MN determines that the type of this SN change failure is a change to an incorrect secondary node (SNChange to wrong cell).

[0220] -Or, the MN determines that the SN to which the UE was connected before the SN change was SN1 based on the information of the SN before the SN currently connected to the UE in the stored UE history information, and determines that the SN where the SCG failure occurred was SN2 based on the information of the SN currently connected to the UE in the stored UE history information. The MN selects a new SN for the UE based on the measurement report carried in the message in which the UE reports the SCG failure. In this embodiment, the new SN is SN3. And the duration of the UE's connection to the SN in the information of SN2 in the UE history message stored by the MN is lower than a pre-configured threshold. Based on the above information, the MN determines that the type of this SN change failure is a change to a wrong secondary node (SN Change to wrong cell).

[0221] The MN may configure the UE to add a secondary node SN3.

[0222] The MN can know that the SN change process is triggered by the MN according to the aforementioned stored information. Therefore, the MN does not need to notify other SNs of the relevant information of the SCG failure.

[0223] The MN can determine the reason for the SN change failure based on the above information, adjust the parameter configuration information corresponding to initiating the SN change according to the reason, and optimize the mechanism for deciding to initiate the SN change process.

[0224] Fig. 9This is a schematic diagram of Embodiment 7 of the present application. Embodiment 7 is the following specific scenario of Embodiment 2: The UE is connected to the MN. The UE is configured to add a secondary node SN1. The MN decides to initiate an SN change process and change the secondary node to SN2. A SCG failure of the UE on SN2 occurs shortly after the SN change is successful, or an SCG failure occurs during the SN change process. The UE is configured to add a secondary node SN3. The MN is an eNB, and SN1, SN2, and SN3 are all en-gNBs.

[0225] Fig. 9 The seventh embodiment shown includes the following steps:

[0226] Step 901: MN sends an X2 signaling SGNB ADDITION REQUEST to SN1, requesting SN1 to configure resources for UE. The signaling carries the Evolved Radio Bearer (E-RAB) information that needs to be configured on SN1, and may also carry SCG configuration information.

[0227] Step 902: After receiving the signaling in the previous step, SN1 allocates resources according to the signaling requirements. SN1 sends an X2 signaling secondary node addition response (SGNB ADDITION REQUEST ACKNOWLEDGE) to the MN to inform the MN of the accepted evolved radio bearer (E-RAB) information. The signaling may carry the new SCG configuration information provided by SN1. MN adds the information of SN1 to the UE History Information saved by MN as the information of the SN to which the UE is currently connected. The information of SN1 may be the SN identification information of SN1, and / or the duration of the UE's connection to the SN, and / or the reason why the UE's SN is configured as SN1. The identification information of the SN includes the PSCell ID, and optionally, may also include the node ID. Optionally, the MN may save the above-mentioned SN1 information as a separate information part instead of adding it to the UE history information.

[0228] MN decides to initiate the SN change process to change the SN of the UE from SN1 to SN2. This SN change process is triggered by MN, and MN saves this information.

[0229] Step 903: MN sends an X2 signaling secondary node addition request (SGNB ADDITION REQUEST) to SN2.

[0230] Step 904: SN2 sends an X2 signaling secondary node addition response (SGNB ADDITION REQUESTACKNOWLEDGE) to MN. MN adds the information of SN2 to the UE History Information saved by MN as the information of the SN to which the UE is currently connected. The information of SN2 may be the SN identification information of SN2, and / or the duration of the UE's connection to the SN, and / or the reason why the UE's SN is configured as SN2. The identification information of the SN includes the PSCell ID, and optionally, may also include the node ID. Optionally, MN may save the above-mentioned SN2 information as a separate information part instead of adding it to the UE History Information.

[0231] Step 905: MN sends an X2 signaling secondary node release request (SGNB RELEASE REQUEST) to SN1 to notify SN1 to release UE-related resources.

[0232] Step 906: After receiving the signaling in the previous step, SN1 stops sending data to the UE. SN1 sends an X2 signaling secondary node release response (SGNB RELEASE REQUEST ACKNOWLEDGE) to the MN.

[0233] Step 907: MN sends an X2 signaling UE CONTEXT RELEASE to SN1. After receiving the signaling, SN1 releases the UE context and its associated resources.

[0234] Within a short period of time after the SN change process is successful, the UE experiences an SCG failure on SN2. Or an SCG failure occurs during the SN change process.

[0235] Step 908: The UE sends a EUTRAN RRC message secondary cell group failure information (SCGFailureInformationNR) to the MN.

[0236] The UE detects that the SCG fails, and reports the SCG failure message to the MN.

[0237] If the SCG failure occurs after the SN change is successful, the message SCGFailureInformationNR may carry the identification information (Previous PSCell ID) of the PSCell to which the SN to which the UE was successfully connected before the SN change, and / or the identification information (Failed PSCell ID) of the PSCell to which the SN where the SCG failure occurred belongs, and / or the duration (timeSCGChangeFailure) between the last successful SN change event and the SCG failure event.

[0238] If an SCG failure occurs during the SN change process, the message SCGFailureInformationNR may carry the identification information of the PSCell to which the SN to which the UE successfully connected before the SN change (Previous PSCell ID), and / or the identification information of the PSCell to which the SN where the SCG failure occurred belongs (Failed PSCell ID). The value of the subfield failureType-r15 of the field FailureReportSCG-NR-r15 carried by the message may be set to scg-ChangeFailure.

[0239] MN updates the duration of the UE connection to the SN in the information of SN2 in the UE history message saved by MN according to the time when the SN to which the UE is currently connected in the UE history message saved by MN is set to SN2 and the time when MN receives the SCG failure message sent by UE.

[0240] The MN can determine the type of SN change failure based on the above information. The method is described in the sixth embodiment.

[0241] The MN may configure the UE to add a secondary node SN3.

[0242] The MN can know that the SN change process is triggered by the MN according to the aforementioned stored information. Therefore, the MN does not need to notify other SNs of the relevant information of the SCG failure.

[0243] The MN can determine the reason for the SN change failure based on the above information, adjust the parameter configuration information corresponding to initiating the SN change according to the reason, and optimize the mechanism for deciding to initiate the SN change process.

[0244] Fig.10 Schematic diagram of Embodiment 8 of the present application. Embodiment 8 is the following specific scenario of Embodiment 3: UE is connected to MN. UE is configured to add a secondary node SN1. SCG failure occurs on SN1 of UE. UE is configured to add a secondary node SN2. MN, SN1, and SN2 are all gNBs.

[0245] Fig.10 The illustrated embodiment eight includes the following steps:

[0246] Step 1001: MN sends an Xn signaling secondary node addition request (S-NODE ADDITION REQUEST) to SN1, requesting SN1 to configure resources for the UE. The signaling carries the PDU session information that needs to be configured on SN1, such as the identifier of the PDU session, the identifier of the QoS flow included in the session, and the quality requirement of the QoS flow. The signaling may also carry SCG configuration information, which contains the capability information of the UE.

[0247] Step 1002: After receiving the signaling in the previous step, SN1 allocates resources according to the signaling requirements. SN1 sends an Xn signaling secondary node addition response (S-NODE ADDITION REQUEST ACKNOWLEDGE) to MN to inform MN of the accepted PDU session information. The signaling can carry the new SCG configuration information provided by SN1, which is sent to MN through an RRC container, and MN sends the SCG configuration information to the UE through an RRC message. The signaling can also carry SN mobility information (SNMobility Information). The information is generated by SN1, which corresponds to a set of SN switching configuration parameters and is a digital identifier associated with the configuration parameters used to determine the SN change. SN provides the information to MN for later analysis of the cause of the erroneous SN switching. For example, SN sends the information to MN, and MN saves the information. If MN receives a message of SN failure reported by the UE, MN can send the information to SN, and SN can determine which parameter / parameters need to be adjusted based on the UE's report information and the configuration information corresponding to SN MobilityInformation. The MN adds the information of SN1 to the UE History Information saved by the MN as the information of the SN to which the UE is currently connected. The information of SN1 may be the SN identification information of SN1, and / or the duration of the UE's connection to the SN, and / or the reason why the UE's SN is configured as SN1. The identification information of the SN includes the PSCell ID, and optionally, may also include the node ID. Optionally, the MN may save the above SN1 information as a separate information part instead of adding it to the UE History Information.

[0248] Step 1003: SCG failure occurs on SN1 of the UE. The UE sends an NR RRC message SCG failure information (SCGFailureInformation) to the MN.

[0249] When the UE detects that the SCG fails, the UE reports the SCG failure to the MN. The message may include one or more of the following information:

[0250] -Identification information of the PSCell to which the SN where the SCG failure occurs belongs (Failed PSCell ID);

[0251] -C-RNTI allocated by SN1 to the UE;

[0252] -C-RNTI allocated by MN to UE.

[0253] MN updates the duration of UE connection to the SN in the information of SN1 in the UE history message saved by MN according to the time when the SN to which the UE is currently connected in the UE history message saved by MN is set to SN1 and the time when MN receives the SCG failure message sent by UE.

[0254] The MN can determine the type of SN change failure based on the above information.

[0255] -Specifically, the MN determines that the SN where the SCG failure occurred is SN1 according to the Failed PSCell ID. The MN selects a new SN for the UE according to the measurement report carried in the message in which the UE reports the SCG failure. In this embodiment, the new SN is SN2. No SN change process occurs before the SCG occurs. Therefore, the MN determines that the type of this SN change failure is SN Change too late.

[0256] -Or, the MN determines that the SN where the SCG failure occurred is SN1 based on the information of the SN currently connected to the UE in the saved UE history information. The MN selects a new SN for the UE based on the measurement report carried in the message in which the UE reports the SCG failure. In this embodiment, the new SN is SN2. And the time duration that the UE is connected to the SN in the information of SN1 in the UE history message saved by the MN is relatively long. Based on the above information, the MN determines that the type of this SN change failure is SN Change too late.

[0257] MN can determine the reason for the SN change failure based on the above information, adjust the parameter configuration information corresponding to the SN change according to the reason, and optimize the mechanism for initiating the SN change process. However, MN cannot determine whether the SN change process to be initiated should be triggered by SN1 or MN. Therefore, MN needs to send relevant information to SN1, see steps 1006, 1008 or 1009.

[0258] Step 1004: MN sends an Xn signaling S-NODE ADDITION REQUEST to SN2, requesting SN1 to configure resources for the UE. The signaling carries the PDU session information that needs to be configured on SN1, and may also carry SCG configuration information.

[0259] Step 1005: After receiving the signaling in the previous step, SN2 allocates resources according to the signaling requirements. SN2 sends an Xn signaling secondary node addition response (S-NODE ADDITION REQUEST ACKNOWLEDGE) to MN to inform MN of the accepted PDU session information. The signaling may carry the new SCG configuration information provided by SN2. MN adds the information of SN2 to the UE History Information saved by MN as the information of the SN to which the UE is currently connected. The information of SN2 may be the SN identification information of SN2, and / or the duration of the UE's connection to the SN, and / or the reason why the UE's SN is configured as SN2. The identification information of the SN includes the PSCell ID, and optionally, may also include the node ID. Optionally, MN may save the above-mentioned SN2 information as a separate information part instead of adding it to the UE history information.

[0260] Step 1006: MN sends an Xn signaling secondary node release request (S-NODE RELEASE REQUEST) to SN1, notifying SN1 to release UE-related resources.

[0261] The signaling may include one or more of the following information:

[0262] -The identifier of the UE on Xn may include the identifier on the Xn interface allocated by the MN and / or SN to the UE.

[0263] - Information about the PDU to be released, such as the PDU Session identifier.

[0264] - After the UE reports the SCG failure, the MN reconfigures the UE and the UE successfully connects to the SN (ServingSN Information). The SN identification information includes the PSCell ID, which may include the node ID and / or the PSCell ID.

[0265] - The RRC message received in step 1001.

[0266] - Information SCG Failure Type, the value is SN change too late, indicating the type of SN change failure determined by the MN. The SCG Failure Type can be SN change too late, SN change too early, and SN change to wrong cell. For example, if the MN determines that the type of SN change failure is SN change too late, the SCG Failure Type can be SN change too late.

[0267] - The information carried in step 1002 is SN mobility information.

[0268] -UE identifier allocated by SN1, which may be C-RNTI and / or an identifier allocated by SN1 to the UE on the Xn interface.

[0269] -UE History Information, where the UE History Information may include SN information, such as identification information of the SNs to which the UE has been connected, and / or the duration of the UE's connection to the SN, and / or the reason for changing the SN.

[0270] - Separate SN information (SN information), the SN information includes the identification information of the SN to which the UE has been connected, and / or the duration of the UE's connection to the SN, and / or the reason for changing the SN.

[0271] Step 1007: SN1 sends an Xn signaling secondary node release response (S-NODE RELEASE REQUESTACKNOWLEDGE) to MN.

[0272] Step 1008: MN sends an Xn signaling UE CONTEXT RELEASE to SN1. After receiving the signaling, SN1 releases the UE context and its associated resources.

[0273] The signaling may include one or more of the following information:

[0274] -The identifier of the UE on Xn may include the identifier on the Xn interface allocated by the MN and / or SN to the UE.

[0275] - After the UE reports the SCG failure, the MN reconfigures the UE and the UE successfully connects to the SN identification information (Serving SNInformation). The SN identification information includes the PSCell ID of the cell to which the SN belongs, and optionally, may include the node ID of the SN.

[0276] -RRC message secondary cell group failure information received in step 1001.

[0277] - Information SCG Failure Type, the value is SN change too late, indicating the type of SN change failure determined by the MN. The SCG Failure Type can be SN change too late, SN change too early, and SN change to wrong cell. For example, if the MN determines that the type of SN change failure is SN change too late, the SCG Failure Type can be SN change too late.

[0278] - The information carried in step 1002 is SN mobility information.

[0279] -UE identifier allocated by SN1, which may be C-RNTI and / or an identifier allocated by SN1 to the UE on the Xn interface.

[0280] -UE History Information, where the UE History Information may include SN information, such as identification information of the SNs to which the UE has been connected, and / or the duration of the UE's connection to the SN, and / or the reason for changing the SN.

[0281] - Separate SN information (SN information), the SN information includes the identification information of the SN to which the UE has been connected, and / or the duration of the UE's connection to the SN, and / or the reason for changing the SN.

[0282] Step 1009: MN may also send an Xn signaling failure indication (Failure Indication) or an Xn signaling handover report (HANDOVER Report) or a newly defined Xn signaling to SN1, which is used to tell SN1 that MN has received the SCG failure report sent by UE and inform SN1 of information related to SCG failure. The signaling may include one or more of the following information:

[0283] - After the UE reports the SCG failure, the MN reconfigures the UE and the UE successfully connects to the SN identification information (Serving SNInformation). The SN identification information includes the PSCell ID of the cell to which the SN belongs, and optionally, may include the node ID of the SN.

[0284] - The RRC message received in step 1001.

[0285] - Information SCG Failure Type, the value is SN change too late, indicating the type of SN change failure determined by the MN. The SCG Failure Type can be SN change too late, SN change too early, and SN change to wrong cell. For example, if the MN determines that the type of SN change failure is SN change too late, the SCG Failure Type can be SN change too late.

[0286] - The information carried in step 1002 is SN mobility information.

[0287] -UE identifier allocated by SN1, which may be C-RNTI and / or an identifier allocated by SN1 to the UE on the Xn interface.

[0288] -UE History Information, where the UE History Information may include SN information, such as identification information of the SNs to which the UE has been connected, and / or the duration of the UE's connection to the SN, and / or the reason for changing the SN.

[0289] - Separate SN information (SN information), the SN information includes the identification information of the SN to which the UE has been connected, and / or the duration of the UE's connection to the SN, and / or the reason for changing the SN.

[0290] After SN1 receives one or more information in step 1006 or 1008 or 1009, if the signaling does not include the field information SCG Failure Type, SN1 can determine the type of SN change failure based on the above information.

[0291] - Specifically, SN1 determines that the SN where the SCG failure occurred is SN1 according to the Failed PSCell ID carried in the RRC message. According to the Serving SN Information, the new SN configured by the MN for the UE is SN2. No SN change process occurred before the SCG occurred. Therefore, SN1 determines that the type of this SN change failure is that the SN change is too late.

[0292] -Or, SN1 determines that the SN where the SCG failure occurred is SN1 based on the received UE history information or SN information, and determines that the SN to which the UE is currently connected is SN2 based on the received UE history information or SN information to which the UE is currently connected. And the length of time that the UE is connected to the SN in the information of SN1 in the UE history information or SN information received by SN1 is longer. Therefore, SN1 determines that the type of this SN change failure is that the SN change is too late.

[0293] If the signaling includes information SCG Failure Type, SN1 can use this as its own judgment, or it can judge the type of SN change failure by itself according to the above method.

[0294] SN1 can determine the reason for the SN change failure based on the above information, find the parameter configuration information corresponding to the SN change according to the SN mobility information and / or the UE identifier assigned by SN1, adjust the parameter configuration information corresponding to the initiation of the SN change according to the reason, and optimize the mechanism for deciding to initiate the SN change process.

[0295] Fig.11 Schematic diagram of Embodiment 9 of the present application. Embodiment 9 is the following specific scenario of Embodiment 3: UE is connected to MN. UE is configured to add a secondary node SN1. UE has SCG failure on SN1. UE is configured to add a secondary node SN2. The MN is an eNB, and SN1 and SN2 are both en-gNB.

[0296] Fig.11 The ninth embodiment shown includes the following steps:

[0297] Step 1101: MN sends an X2 signaling secondary node addition request (SGNB ADDITION REQUEST) to SN1, requesting SN1 to configure resources for the UE. The signaling carries the evolved radio bearer (E-RAB) information that needs to be configured on SN1, such as the E-RAB identifier and the quality requirements of the E-RAB. The signaling may also carry SCG configuration information, which includes the capability information of the UE.

[0298] Step 1102: After receiving the signaling in the previous step, SN1 allocates resources according to the signaling requirements. SN1 sends an X2 signaling secondary node addition response (SGNB ADDITION REQUEST ACKNOWLEDGE) to MN to notify MN of the accepted evolved radio bearer (E-RAB) information. The signaling can carry the new SCG configuration information provided by SN1, which is sent to MN through an RRC container, and MN sends the SCG configuration information to the UE through an RRC message. The signaling can also carry information SN mobility information (SN Mobility Information). The information is generated by SN1, which corresponds to a set of SN switching configuration parameters and is a digital identifier associated with the configuration parameters used to determine the SN change. SN provides the information to MN for later analysis of the cause of the erroneous SN switching. For example, SN sends the information to MN, and MN saves the information. If MN receives a message of SN failure reported by the UE, MN can send the information to SN, and SN can determine which parameter / parameters need to be adjusted based on the report information of the UE and the configuration information corresponding to the SN mobility information. The MN adds the information of SN1 to the UE History Information saved by the MN as the information of the SN to which the UE is currently connected. The information of SN1 may be the SN identification information of SN1, and / or the duration of the UE's connection to the SN, and / or the reason why the UE's SN is configured as SN1. The identification information of the SN includes the PSCell ID, and optionally, may also include the node ID. Optionally, the MN may save the above SN1 information as a separate information part instead of adding it to the UE History Information.

[0299] Step 1103: SCG failure occurs in UE on SN1. UE sends EUTRAN RRC message SCG failure information (SCGFailureInformationNR) to MN.

[0300] The UE detects that the SCG fails, and reports the SCG failure message to the MN.

[0301] The message may include one or more of the following information:

[0302] -Identification information of the PSCell to which the SN where the SCG failure occurs belongs (Failed PSCell ID);

[0303] -C-RNTI allocated by SN1 to the UE;

[0304] -C-RNTI allocated by MN to UE.

[0305] MN updates the duration of UE connection to the SN in the information of SN1 in the UE history message saved by MN according to the time when the SN to which the UE is currently connected in the UE history message saved by MN is set to SN1 and the time when MN receives the SCG failure message sent by UE.

[0306] The MN can determine, based on the above information, that the type of SN change failure is that the SN change is too late. The method is described in the eighth embodiment.

[0307] MN can determine the reason for the SN change failure based on the above information, adjust the parameter configuration information corresponding to the initiation of the SN change based on the reason, and optimize the mechanism for initiating the SN change process. However, MN cannot determine whether the SN change process that should occur should be triggered by SN1 or MN, because the reason for the failure of SCG at this time is that the SN change is initiated too late, which means that MN or / and SN did not initiate the SN change process, and the configuration parameters that trigger the SN change on MN or / and SN may have problems. Therefore, MN needs to send relevant information to SN1, see step 1106 or 1108 or 1109.

[0308] Step 1104: MN sends an X2 signaling SGNB ADDITION REQUEST to SN2, requesting SN1 to configure resources for the UE. The signaling carries the Evolved Radio Bearer (E-RAB) information that needs to be configured on SN1, and may also carry SCG configuration information.

[0309] Step 1105: After receiving the signaling in the previous step, SN2 allocates resources according to the signaling requirements. SN2 sends an X2 signaling secondary node addition response (SGNB ADDITION REQUEST ACKNOWLEDGE) to the MN to inform the MN of the accepted evolved radio bearer (E-RAB) information. The signaling may carry the new SCG configuration information provided by SN2. MN adds the information of SN2 to the UE History Information saved by the MN as the information of the SN to which the UE is currently connected. The information of SN2 may be the SN identification information of SN2, and / or the duration of the UE's connection to the SN, and / or the reason why the UE's SN is configured as SN2. The identification information of the SN includes the PSCell ID, and optionally, may also include the node ID. Optionally, the MN may save the above-mentioned SN2 information as a separate information part instead of adding it to the UE history information.

[0310] Step 1106: MN sends an X2 signaling secondary node release request (SGNB RELEASE REQUEST) to SN1, notifying SN1 to release UE-related resources.

[0311] The signaling may include one or more of the following information:

[0312] -The identifier of the UE on X2 may include the identifier on the X2 interface allocated by the MN and / or SN to the UE.

[0313] - Information about the E-RAB bearer to be released, such as the E-RAB bearer identity.

[0314] - After the UE reports the SCG failure, the MN reconfigures the UE and the UE successfully connects to the SN identification information (Servng SNInformation). The SN identification information includes the PSCell ID of the cell to which the SN belongs, and optionally, the node ID of the SN.

[0315] -RRC message NR secondary cell group failure information received in step 1101.

[0316] - The field information SCG Failure Type indicating the type of SN change failure determined by the MN. The SCG Failure Type may be SN change too late, SN change too early, and SN change to wrong cell. For example, if the MN determines that the type of SN change failure is SN change to wrong cell, the SCG Failure Type may be SN change to wrong cell.

[0317] -The information carried in step 1102 is SN mobility information.

[0318] -UE identifier allocated by SN1, which may be C-RNTI and / or an identifier allocated by SN1 to the UE on the X2 interface.

[0319] -UE History Information, where the UE History Information may include SN information, such as identification information of the SNs to which the UE has been connected, and / or the duration of the UE's connection to the SN, and / or the reason for changing the SN.

[0320] - Separate SN information (SN information), the SN information includes the identification information of the SN to which the UE has been connected, and / or the duration of the UE's connection to the SN, and / or the reason for changing the SN.

[0321] Step 1107: SN1 sends an X2 signaling SGNB RELEASE REQUEST ACKNOWLEDGE to MN.

[0322] Step 1108: MN sends an X2 signaling UE CONTEXT RELEASE to SN1. After receiving the signaling, SN1 releases the UE context and its associated resources.

[0323] The signaling may include one or more of the following information:

[0324] -The identifier of the UE on X2 may include the identifier on the X2 interface allocated by the MN and / or SN to the UE.

[0325] - After the UE reports the SCG failure, the MN reconfigures the UE and the UE successfully connects to the SN identification information (Serving SNInformation). The SN identification information includes the PSCell ID of the cell to which the SN belongs, and optionally, the node ID of the SN.

[0326] -RRC message NR secondary cell group failure information received in step 1101.

[0327] - The field information SCG Failure Type indicating the type of SN change failure determined by the MN. The SCG Failure Type may be SN change too late, SN change too early, and SN change to wrong cell. For example, if the MN determines that the type of SN change failure is SN change to wrong cell, the SCG Failure Type may be SN change to wrong cell.

[0328] -The information carried in step 1102 is SN mobility information.

[0329] -UE identifier allocated by SN1, which may be C-RNTI and / or an identifier allocated by SN1 to the UE on the X2 interface.

[0330] -UE History Information, where the UE History Information may include SN information, such as identification information of the SNs to which the UE has been connected, and / or the duration of the UE's connection to the SN, and / or the reason for changing the SN.

[0331] - Separate SN information (SN information), the SN information includes the identification information of the SN to which the UE has been connected, and / or the duration of the UE's connection to the SN, and / or the reason for changing the SN.

[0332] Step 1109: MN may also send an X2 signaling failure indication (RLF INDICATION) or an X2 signaling handover report (HANDOVER REPORT) or a newly defined X2 signaling to SN1. The signaling may include one or more of the following information:

[0333] - After the UE reports the SCG failure, the MN reconfigures the UE and the UE successfully connects to the SN identification information (Serving SNInformation). The SN identification information includes the PSCell ID of the cell to which the SN belongs, and optionally, the node ID of the SN.

[0334] - The RRC message received in step 1101.

[0335] - The field information SCG Failure Type indicating the type of SN change failure determined by the MN. The SCG Failure Type may be SN change too late, SN change too early, and SN change to wrong cell. For example, if the MN determines that the type of SN change failure is SN change to wrong cell, the SCG Failure Type may be SN change to wrong cell.

[0336] -The information carried in step 1102 is SN mobility information.

[0337] -UE identifier allocated by SN1, which may be C-RNTI and / or an identifier allocated by SN1 to the UE on the X2 interface.

[0338] -UE History Information, where the UE History Information may include SN information, such as identification information of the SNs to which the UE has been connected, and / or the duration of the UE's connection to the SN, and / or the reason for changing the SN.

[0339] - Separate SN information (SN information), the SN information includes the identification information of the SN to which the UE has been connected, and / or the duration of the UE's connection to the SN, and / or the reason for changing the SN.

[0340] After SN1 receives the one or more information in step 1106, 1108 or 1109, if the signaling does not include the field information SCG Failure Type, SN1 can determine the type of SN change failure is SN change too late based on the above information. The method is described in the eighth embodiment.

[0341] If the signaling includes information SCG Failure Type, SN1 can use this as its own judgment, or it can judge the type of SN change failure by itself according to the above method.

[0342] SN can determine the reason for the SN change failure based on the above information, find the parameter configuration information corresponding to the SN change based on the SN mobility information and / or the UE identifier assigned by SN1, adjust the parameter configuration information corresponding to the initiation of the SN change based on the reason, and optimize the mechanism for deciding to initiate the SN change process.

[0343] According to the third embodiment of the present application, when the UE is successfully connected to the target secondary node, the UE sends a report message about the success of the secondary cell group SCG to the MN.

[0344] Optionally, a new EUTRAN RRC message SuccessfulSCGChangeReport is added as a report message. The message may include the PSCell ID of the cell to which the connected SN belongs, signal quality RSRP and / or RSRQ and / or SINR. Optionally, a new NR RRC message SuccessfulSCGChangeReport is added as a report message. The message may include the connected PSCell ID, beam-related signal quality RSRP and / or RSRQ and / or SINR.

[0345] Fig.12 This is a schematic diagram of Embodiment 10 of the present application, which describes the following scenario:

[0346] The first node UE sends a NR RRC message secondary cell group successful change report (SuccessfulSCGChangeReport) or an EUTRAN RRC message secondary cell group successful change report (SuccessfulSCGChangeReport) to the second node. The second node may be an access node, such as an MN or SN. The MN or SN may be a gNB, an eNB, or an ng-eNB.

[0347] After successfully executing the SN change process, the UE generates information Successful SCGChange Report. The information includes parameters related to the SN change, such as the UE's own configuration parameters and measurement results. The UE sends the information to the second node. The second node can optimize the mechanism for determining the generated SN change based on the information.

[0348] Specifically, in step 1201, if the second node is a gNB, the first node sends an NR RRC message SuccessfulSCGChangeReport to the second node. The message may carry the PSCell ID of the SN to which the UE is connected, and beam-related signal quality RSRP and / or RSRQ and / or SINR. If the second node is an eNB or ng-eNB, the first node sends an EUTRAN RRC message SuccessfulSCGChangeReport to the second node. The message may carry the PSCell ID to which the UE is connected, and signal quality RSRP and / or RSRQ and / or SINR.

[0349] According to the fourth implementation of the present application, at least one of the following information is recorded in the Xn message or the X2 message: the identifier of each secondary node to which the UE has been connected, the duration of the connection between the UE and each secondary node, and the reason for each secondary node switching.

[0350] Optionally, the SN identification information to which the UE has been connected, and / or the duration of the UE's connection to the SN, and / or the reason for changing the SN are added to the existing Xn information UE History Information. New information UE History Information may be added to the existing Xn message. The Xn message may be a secondary node addition request (S-NODE ADDITION REQUEST) or a UE context release (UE CONTEXT RELEASE). Or new information SN information is added to the Xn message. The SN information includes the SN identification information to which the UE has been connected, and / or the duration of the UE's connection to the SN, and / or the reason for changing the SN. The SN identification information may be a node ID and / or a PSCell ID. The Xn message may be a secondary node addition request (S-NODE ADDITION REQUEST), or a UE context release (UE CONTEXT RELEASE), or a handover request (HANDOVER REQUEST).

[0351] Optionally, the SN identification information to which the UE has been connected, and / or the duration of the UE's connection to the SN, and / or the reason for changing the SN are added to the existing X2 information UE History Information. New information UE History Information is added to the existing X2 message. The Xn message may be a secondary node addition request (SGNB ADDITION REQUEST) or a UE context release (UE CONTEXT RELEASE). Or new information SN information is added to the X2 message. The SN information includes the SN identification information to which the UE has been connected, and / or the duration of the UE's connection to the SN, and / or the reason for changing the SN. The SN identification information may be a node ID and / or a PSCell ID. The X2 message may be a secondary node addition request (SGNB ADDITION REQUEST), or a UE context release (UE CONTEXT RELEASE), or a handover request (HANDOVER REQUEST).

[0352] Fig.13 This is a schematic diagram of Embodiment 11 of the present application, which describes the following scenario: the first node MN1 sends an Xn message handover request (HANDOVER REQUEST) or an X2 message handover request (HANDOVER REQUEST) to the second node MN2. The first node and the second node may be gNB, or eNB, or ng-eNB.

[0353] Specifically, in step 1301, the first node MN1 sends a handover request signaling to the second node MN2, informing the second node to prepare for the handover process.

[0354] The signaling may carry one or more of the following information:

[0355] -UE History Information, where the UE History Information may include the identification information of the SNs to which the UE has been connected, and / or the duration for which the UE has been connected to the SN, and / or the reason for changing the SN.

[0356] -SN information: The SN information includes the identification information of the SN to which the UE has been connected, and / or the duration of the UE's connection to the SN, and / or the reason for changing the SN.

[0357] The SN identification information includes the PSCell ID of the cell to which the SN belongs, and optionally, may also include the node ID of the SN.

[0358] If the first node and the second node are gNBs, the signaling is an Xn signaling handover request message (HANDOVERREQUEST). If the first node and the second node are eNBs, the signaling is an X2 signaling handover request message (HANDOVERREQUEST).

[0359] Fig.14 This is a schematic diagram of Embodiment 12 of the present application, which describes the following scenario: Base station 1 initiates a handover process to base station 2, and a wireless connection failure occurs on base station 2 within a short time after successful handover. The UE reconnects to base station 3 and then successfully switches to base station 4. The UE sends a wireless connection failure report to base station 4. The wireless connection failure report is finally forwarded to base station 1 through inter-base station signaling. In this embodiment, the base station 1 to base station 4 is NG-RAN node 1 to NG-RAN node 4, and the inter-base station signaling is Xn signaling.

[0360] The UE sends a wireless connection failure report describing the wireless connection failure information to the NG-RAN node 4. There is an Xn connection between the NG-RAN node 4 and the NG-RAN node 2, and between the NG-RAN node 2 and the NG-RAN node 1. The NG-RAN node 1 and the NG-RAN node 3 are ng-eNBs, and the NG-RAN node 2 and the NG-RAN node 4 are gNBs; or the NG-RAN node 1 and the NG-RAN node 3 are gNBs, and the NG-RAN node 2 and the NG-RAN node 4 are ng-eNBs. Optionally, the UE reports a mobility history information report, and the mobility history information report includes the cell identification information of the secondary cell group SCG cell to which the UE has been connected, and / or the duration of the UE's connection to the cell.

[0361] Step 1401: NG-RAN node 4 receives a wireless connection failure report sent by UE, and learns from the failed cell information carried in the wireless connection failure report that the wireless connection failure related to the wireless connection failure report occurs in NG-RAN node 2. NG-RAN node 4 sends an Xn signaling failure indication (FAILURE INDICATION) to NG-RAN node 2 to notify NG-RAN node 2 that a wireless connection failure has occurred before. The signaling carries a wireless connection failure report describing the wireless connection failure information, and / or UE history information (UE History Information), and / or a mobile history information report reported by the UE. The UE history information here may include the same information as the UE history information in the aforementioned embodiment.

[0362] If the NG-RAN node 1 and the NG-RAN node 3 are ng-eNB, the NG-RAN node 2 and the NG-RAN node 4 are gNB, the wireless connection failure report is defined in the 3GPP specification TS38.331; if the NG-RAN node 1 and the NG-RAN node 3 are gNB, the NG-RAN node 2 and the NG-RAN node 4 are ng-NB, the wireless connection failure report is defined in the 3GPP specification TS36.331.

[0363] Step 1402: NG-RAN node 2 learns from the source cell information carried in the received wireless connection failure report that the source base station of the handover process before the wireless connection failure occurs is NG-RAN node 1. NG-RAN node 2 can learn from the received wireless connection failure report or UE history information or the mobile history information report reported by the UE that the UE reconnects to NG-RAN node 3 after the handover failure. NG-RAN node 2 determines the type of wireless connection failure as a handover to the wrong cell (HO to the wrong cell) based on the above information. NG-RAN node 2 sends an Xn signaling handover report (HANDOVER REPORT) to NG-RAN node 1. In addition to the failure type and handover cause, the signaling may also carry one or more of the following information:

[0364] -Source cell information.

[0365] -Failed cell information.

[0366] - Report of wireless connection failure.

[0367] -The UE history information.

[0368] -Mobile history information report reported by UE.

[0369] NG-RAN node 1 may use the received failure type as its own judgment, or may judge the failure type by itself according to the received information. For example, the source cell belongs to NG-RAN node 1, and NG-RAN node 1 learns from the wireless connection failure report that it successfully switched to NG-RAN node 2 but a wireless connection failure soon occurs. According to the UE historical information or the mobile history information report reported by the UE, it is learned that the UE is reconnected to NG-RAN node 3. Therefore, NG-RAN node 1 may judge that the failure type is switching to the wrong node (HO to wrong cell).

[0370] The NG-RAN node 1 can adjust the parameter configuration information corresponding to initiating the handover according to the above information, and optimize the mechanism for deciding to initiate the handover process.

[0371] If there is no Xn connection between the NG-RAN node 4 and the NG-RAN node 2, or between the NG-RAN node 2 and the NG-RAN node 1, the radio connection failure report and the UE history information and / or the mobility history information report reported by the UE may be forwarded through the core network node, such as by using Ng signaling. The Ng signaling may be an uplink access network configuration transfer (UPLINKRAN CONFIGURATION TRANSFER) and / or a downlink access network configuration transfer (DOWNLINK RAN CONFIGURATION TRANSFER).

[0372] Fig.15 A simplified block diagram of an entity 1500 suitable for practicing many exemplary embodiments of the present application is shown. The entity 1500 may be configured as a MN, a SN or a UE.

[0373] like Fig.15 As shown, entity 1500 includes a processor 1501, a memory 1502 coupled to the processor 1501, and a suitable transmitter / receiver 1504 coupled to the processor 1501. The memory 1502 stores a program 1503. The transmitter / receiver 1504 is suitable for two-way wireless communication. Note that the transmitter / receiver 1504 has at least one antenna to assist in communication. The entity 1500 can be coupled to one or more external networks or systems, such as the Internet, via a data path. The program 1503 can include program instructions that, when executed by the associated processor 1501, cause the entity 1500 to operate in accordance with the various exemplary embodiments of the present application.

[0374] The embodiments of the present application may be implemented by computer software, hardware, firmware, or any appropriate combination thereof that is executable by the processor 1501 of the entity 1500 .

[0375] Memory 1502 may be any suitable type of memory suitable for the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor-based storage devices and systems, magnetic storage devices and systems, optical storage devices and systems, fixed memory, and removable memory, as non-limiting examples only. Although only one memory is shown in entity 1500, multiple physically independent storage units may exist in entity 1500. Processor 1501 may be any suitable type of processor suitable for the local technical environment and may include one or more of the following: a general-purpose computer, a special-purpose computer, a microprocessor, a digital signal processor (DSP), and a processor based on a multi-core processor architecture, as non-limiting examples only.

[0376] It should be understood that the various units included in the entity 1500 are configured to practice the exemplary embodiments disclosed herein. Figures 3 to 14 The described operations and features are also applicable to entity 1500 and the units therein, and their detailed description is omitted here.

[0377] As another aspect, the present application further provides a computer-readable storage medium, which may be a computer-readable storage medium included in the MN, SN or UE in the above embodiments; or a computer-readable storage medium that exists independently and is not assembled into a device. The computer-readable storage medium stores one or more programs, and the programs are used by one or more processors to execute the communication method described in the present application.

[0378] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the above features are replaced with (but not limited to) technical features with similar functions disclosed in the present application.

Claims

1. A method performed by a master node MN in a mobile communication network, comprising: receiving a first message from a source secondary node, the first message being associated with a secondary node SN change of a user equipment UE, the first message comprising SN movement information related to the SN change; receiving a second message from the UE, where the second message includes information about a failure of a secondary cell group (SCG), where the information about the SCG failure includes a type of failure; Determining that the SCG failure is related to the source secondary node; as well as Sending a third message related to the SCG failure to the source secondary node or the first target secondary node.

2. The method of claim 1, further comprising: Determining a second target secondary node associated with the SN change; After receiving the second message, sending a fourth message to the second target secondary node, wherein the fourth message includes information related to requesting the second target secondary node to establish a new connection; The third message includes: identification information of the second target secondary node.

3. The method of claim 1, wherein: The first message is received from the source secondary node through Xn signaling.

4. The method of claim 1, further comprising: It is determined that the SN change of the UE is triggered by the source secondary node.

5. The method of claim 1, wherein: The third message includes: The node ID of the first target secondary node where the SCG failure occurs, the node ID of the secondary node to which the UE successfully connects before the SN change, SN mobility information, and information related to the information about the SCG failure.

6. The method of claim 5, wherein: The third message is sent to the source secondary node through Xn signaling.

7. The method of claim 1, further comprising: In a case where the SN is changed successfully from the source secondary node to the first target secondary node, information for reporting the success of the SCG change is received from the UE.

8. A method performed by a source secondary node in a mobile communication network, comprising: Sending a first message to a master node MN, where the first message is associated with a change in a secondary node SN of a user equipment UE, and the first message includes SN mobility information related to the SN change; as well as Based on the failure of the secondary cell group SCG related to the source secondary node, receiving a third message related to the SCG failure from the master node MN; The third message is sent by the master node MN after receiving the second message sent by the UE, the second message includes information about the failure of the secondary cell group SCG, and the information about the SCG failure includes the type of failure.

9. The method of claim 8, wherein: The first message is sent to the master node MN through Xn signaling.

10. The method of claim 8, further comprising: The type of the SN change failure is determined according to the third message.

11. The method of claim 10, wherein: The type of the SN change failure includes at least one of: changing to the target secondary node too late, changing to the target secondary node too early, or changing to a wrong secondary node.

12. The method of claim 8, wherein: The third message includes: the node ID of the first target secondary node where the SCG failure occurs, the node ID of the secondary node to which the UE is successfully connected before the SN change, SN movement information, and information related to the information about the SCG failure.

13. The method of claim 8, wherein: The third message is sent from the master node via Xn signaling.

14. A method performed by a user equipment UE in a mobile communication network, comprising: determining that a secondary node SN change is not successfully performed, the SN change comprising changing a connection from a source secondary node to a first target secondary node or failing to successfully connect to the source secondary node; as well as Sending a second message to the master node MN, wherein the second message includes information about the failure of the secondary cell group SCG, and the information about the failure of the SCG includes the type of failure, The second message is sent after the master node MN receives the first message sent by the source slave node, the first message is associated with the SN change, and the first message includes SN movement information related to the SN change.

15. A master node in a mobile communication network, comprising: a memory storing computer instructions; and A processor, the processor executing the computer instructions to perform the method of any one of claims 1 to 7.

16. A secondary node in a mobile communication network, comprising: a memory storing computer instructions; and A processor that executes the computer instructions to perform the method of any one of claims 8 to 13.

17. A user equipment UE in a mobile communication network, comprising: a memory storing computer instructions; and A processor that executes the computer instructions to perform the method of claim 14.

18. A computer-readable storage medium storing computer instructions, wherein when the computer instructions are executed by a processor, the processor executes the method according to any one of claims 1 to 17.

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