Self-optimization method and apparatus

Abstract

A self-optimization method in a wireless communication system is disclosed. The method comprises: determining, by a second node, a type of a secondary node (SN) change failure based on a first message received from a first node, and sending a second message to a node triggering the SN change for self-optimization configuration.

Description

Technical Field

[0001] This disclosure relates to self-optimization methods, and more particularly to self-optimization methods and apparatus for user equipment (UE) when a secondary cell group (SCG) radio connection fails on a secondary node (SN). Background Technology

[0002] To meet the increased demand for wireless data traffic since the deployment of 4G communication systems, improved 5G or near-5G communication systems have been developed. Therefore, 5G or near-5G communication systems are also referred to as "super 4G networks" or "post-LTE systems." 5G communication systems are implemented in higher frequency (mmWave) bands (e.g., the 60GHz band) to achieve higher data rates. To reduce radio wave propagation loss and increase transmission distance, beamforming, massive MIMO, full-dimensional MIMO (FD-MIMO), array antennas, analog beamforming, and massive MIMO technologies are discussed in 5G communication systems.

[0003] In 5G or near-5G communication systems, user equipment (UE) can be in a dual-connectivity state, meaning that the UE can establish a wireless connection with one access node while simultaneously establishing a wireless connection with another access node. The access node can be a base station supporting Long Term Evolution (LTE) air interface technology (including eNB (evolved NodeB) or ng-eNB (eNB connected to the 5G core network)), a base station supporting New Radio (NR) (including gNB or en-gNB (gNB in ​​E-UTRAN, where the en-gNB acts as a secondary base station if the eNB is the primary base station), or a base station supporting other air interface access technologies.

[0004] At the same time, the access nodes connected to the UE are, one of which is the master node (MN) and the other is the secondary node (SN). Figure 1 This is a schematic diagram illustrating a UE simultaneously establishing wireless connections with two access nodes. Figure 1 The diagram illustrates the core network, primary node (MN), secondary node (SN), and user equipment (UE). For example... Figure 1 As shown, the UE establishes radio connections with both the primary node and the secondary node simultaneously. The MN can connect to the UE via the control plane (shown by solid lines) and the user plane (shown by dashed lines), while the SN can connect to the UE via the user plane (shown by dashed lines). Here, the MN can be a node providing radio connectivity services to the UE and connecting to the core network, including an eNB, ng-eNB, or gNB, while the SN can be a node providing radio connectivity services to the UE, including an eNB, ng-eNB, en-gNB, or gNB. Summary of the Invention

[0005] Aspects and advantages of embodiments of this disclosure will be set forth in part in the description which follows, or may be learned from the description, or may be acquired through practice of the embodiments.

[0006] The UE may experience SCG radio connection failure on the SN. However, no comprehensive solution has yet been proposed regarding how to detect the failure, the cause or type of failure, and how to better optimize the configuration based on the findings to avoid subsequent potential failures.

[0007] This disclosure proposes a flexible method that, based on the inventive principles outlined herein, can report failure information to the node where the error occurred, identify the cause of the failure, and perform reasonable self-optimization accordingly. This avoids subsequent failures and improves the user experience for the UE (User Equipment).

[0008] This disclosure proposes a self-optimization method for secondary node change failure. The method includes a second node determining the type of secondary node SN change failure based on a first message received from a first node, and sending a second message to the node that triggered the SN change for self-optimization configuration.

[0009] According to one aspect of the embodiments of this disclosure, a self-optimizing method for auxiliary node changes is provided.

[0010] The UE can establish a radio connection with both MN and SN1 simultaneously, and either MN or SN1 can decide whether to initiate an SN change; that is, either MN or SN1 can trigger the SN change process.

[0011] SN1 can add Mobility Information to the secondary node's request response message. This Mobility Information refers to a numerical identifier generated by the SN and associated with the configuration parameters within the SN used to determine SN changes. If SN1 initiates an SN change, it can use this identifier to locate the configuration parameters within SN that determine the SN change. MN stores this information for future reference.

[0012] If a subsequent SN change occurs, SN1 will be the source SN for the change. For potential SN change failures, the source SN is one piece of information used to determine the type of failure. This information can be obtained either by the UE reporting it in an RRC message, or by the MN retrieving it from the SN and storing it on the MN when configuring the SN for the UE. In the latter case, the MN can add the SN1 information to the list of SNs connected to the UE in the UE History Information stored on the MN. This list can include information about one or more SNs connected to the UE. The information about the SN connected to the UE can be the SN's identification information, and / or the duration of the UE's connection to the SN, and / or the reason the UE's SN was configured as that SN, and / or the information of the MN associated with that SN. The SN's identification information includes the cell identifier of the primary / secondary cell (PSCell), and optionally, it can also include the Tracking Area Code (TAC) and PLMN identifier, or Tracking Area Identifier (TAI), and / or the SN's node ID. The information of the MN may be the PCell ID, and / or the TAC and PLMN identifier to which the Cell belongs, or the TAI, and / or the node ID of the MN. Optionally, the MN may save the list as a separate information section instead of adding it to the UE history information.

[0013] If MN or SN1 fails to initiate the SN change procedure from SN1 to SN2 as required, the UE will experience a radio connection failure on SN1; or if MN or SN1 decides to initiate the SN change procedure from SN1 to SN2 at an inopportune time, the UE will experience a radio connection failure on SN2 during the SN change procedure or shortly after the SN change procedure is successfully completed.

[0014] If the MN or SN1 initiates an SN change process from SN1 to SN2, SN2 is the target SN for the SN change. In the event of a potential SN change failure, SN2 will be the SN where the SCG radio connection failure occurred. The SN where the SCG radio connection failure occurred is one of the pieces of information used to determine the type of SN change failure. This information can be obtained either by the UE reporting it in an RRC message, or by the MN retrieving it from the SN and storing it on the MN when configuring the SN for the UE. In the latter case, the MN adds the information of SN2 to the saved list of SNs connected to the UE, as described above.

[0015] Since the MN may receive secondary cell group (SCG) failure information from the UE, the MN can send it to the SN where the SCG radio connection failure occurred to analyze and determine the type of SN change failure. Then, the SN can send the SCG failure information and / or the determination result to the node that initiated the SN change for self-optimization. The node initiating the SN change may be the MN or the source SN. The SN where the SCG radio connection failure occurred needs to know whether the node initiating the SN change is the MN or the source SN. Specifically, the MN notifies the SN, indicating whether the current SN change process was initiated by the MN or the SN, and / or determines the information of the SN that initiated the SN change. The SN information may be the SN's node ID, optionally including the TAC and PLMN identifiers, or TAI; and / or the cell identifier of the SN's PSCell, optionally including the TAC and PLMN identifiers, or TAI. The notification information can be sent using a secondary node addition request message, or later using a failure indication message. The failure indication message can also be a secondary cell group (SCG) failure indication or other messages.

[0016] The UE sends a secondary cell group (SCG) failure message to the MN. For example, the message may include one or more combinations of the following:

[0017] The cell identifier of the PSCell of the SN where the SCG wireless connection failure occurred may optionally include the TAC and PLMN identifiers, or TAI, to which the cell belongs.

[0018] The cell identifier of the PSCell of the source SN during the last SN change process may optionally include the TAC and PLMN identifiers, or TAI, to which the cell belongs;

[0019] The cell identifier of a cell of an SN suitable for UE access after the UE reports an SCG failure. Optionally, it may also include the TAC and PLMN identifiers of the cell, or TAI;

[0020] The interval between the last SN change process and the SCG radio connection failure can be the time from when the UE received the RRC reconfiguration message containing SN change information to the SCG failure or the time from when the UE sent the SN reconfiguration completion message to the SCG failure.

[0021] The types of SCG wireless connection failures can be SN change failure or radio link failure.

[0022] The identifier C-RNTI assigned to the UE by the SN when an SCG radio connection failure occurs;

[0023] The identifier C-RNTI assigned to the UE by the source SN during the last SN change process;

[0024] The identifier C-RNTI assigned by the MN to the UE;

[0025] UE measurement report.

[0026] The interval between the last SN change process and the SCG radio connection failure is one of the pieces of information used to determine the type of SN change failure. The MN can also calculate the interval between the last SN change process and the SCG radio connection failure based on the time of the last SN change process (which could be the time the MN sent the last RRC reconfiguration message containing SN change information or the time the MN received the SN reconfiguration completion message) and the time it received the SCG failure information from the UE. The type of SCG radio connection failure is also one of the pieces of information used to determine the type of SN change failure. The MN can also determine the type of SCG radio connection failure based on whether the SN change process was successfully completed. For example, if the SN change process was successfully completed, the MN can determine that the SCG radio connection failure is a radio link failure; otherwise, the MN can determine that the SCG radio connection failure is an SN change failure.

[0027] The appropriate access cell can be sent by the UE to the MN, which in turn sends it to the SN; it can also be determined by the SN based on the UE's measurement report; or it can be a cell on another SN that the MN decides to configure for the UE, which is then sent to the SN by the MN.

[0028] The appropriate SN cell for access is one of the pieces of information used to determine the type of SN change failure. The MN can add the information of the new SN selected for the UE to the saved list of SNs connected to the UE. As mentioned above, the information of the new SN includes the cell identifier of the cell to which the SN belongs, and optionally, it may also include the TAC and PLMN identifiers, or TAI, of the cell, and / or the node ID of the SN. If the SN change is too late, the appropriate SN for access can be SN2; if the SN change is too early, the appropriate SN for access can be SN1; if the change is to an incorrect SN cell, the appropriate SN for access can be SN3.

[0029] The MN can send SCG failure information to the SN for analysis. In this embodiment, the SN is the SN where the SCG radio connection failure occurred. The MN sends a failure indication message to the SN. The failure indication message can also be a Secondary Cell Group (SCG) failure indication or other messages, used to send SCG failure information to the SN. The message contains information about whether the MN or the SN triggered the previous SN change process, and / or information about the SN that decided to initiate the SN change. The SN information can be the SN's node ID, optionally including the TAC and PLMN identifier, or TAI, to which the node belongs; and / or the SN's PSCell cell identifier, optionally including the TAC and PLMN identifier, or TAI, to which the cell belongs. The message also includes at least one of the following information:

[0030] The SCG failure information;

[0031] The identifier assigned to the UE by the SN when the SCG radio connection fails. This identifier can be the S-NG-RAN node UE XnAP ID in the Xn message or the SgNB UE X2AP ID in the X2 message, or it can be C-RNTI;

[0032] The identifier assigned to the UE by the source SN during the last SN change process; the identifier may be C-RNTI.

[0033] The identifier assigned to the UE by the MN. This identifier can be the M-NG-RAN node UE XnAP ID in the Xn message or the MeNB UE X2AP ID in the X2 message, or it can be a C-RNTI;

[0034] The types of SCG wireless connection failures can be SN change failure or radio link failure.

[0035] The cell identifier of the PSCell of the source SN that the SN changes may optionally include the TAC and PLMN identifiers, or TAI, to which the cell belongs;

[0036] The cell identifier of the PSCell of the SN where the SCG wireless connection failure occurred may optionally include the TAC and PLMN identifiers, or TAI, to which the cell belongs.

[0037] The cell identifier of a cell of a suitable SN to access after a wireless connection failure may optionally include the TAC and PLMN identifiers, or TAI, to which the cell belongs.

[0038] The interval between the last SN change process and the SCG wireless connection failure;

[0039] Information list of SNs to which the UE is connected, or UE history information containing information list of SNs to which the UE is connected;

[0040] Mobility Information.

[0041] The SN that experiences an SCG radio connection failure can determine the type of SN change failure based on the received information. The failure type can be SN change too late, SN change too early, or SN change to the wrong cell. For example, if the UE has been camped on a cell of the SN for a long time (without recent SN changes), and the UE has a suitable cell on another SN for access when the failure occurs, the failure type can be determined as SN change too late. If the UE recently underwent an SN change, and the SN of the source cell of the SN change is a suitable SN for the UE to access after the failure, or the source cell of the SN change is a suitable SN for the UE to access after the failure, the failure type can be determined as SN change too early. If the UE recently underwent an SN change, and the suitable SN for the UE to access after the failure is neither the source SN of the previous SN change nor the SN where the failure occurred, nor the destination SN of the SN change, the failure type can be determined as SN change to the wrong cell.

[0042] If the SN changes too late, the SN that experiences SCG radio connection failure may know that it or the MN should trigger an SN change process, but neither does, leading to UE failure on the SN. Therefore, both the SN and MN that experience SCG radio connection failure are problematic nodes. The SN that experiences SCG radio connection failure can perform appropriate self-optimization.

[0043] The SN experiencing an SCG wireless connection failure can send a handover report message to the node that decided on the SN change, based on information from the previous message indicating whether the MN or the SN triggered the previous SN change process. This information is then used by the node to analyze and optimize the parameters that led to the SN change decision. The handover report can also be an SCG change report or other messages. The message contains one or more combinations of the following information:

[0044] The SCG failure information;

[0045] The types of SN change failures can be SN change too late, SN change too early, or SN change to the wrong cell;

[0046] The identifier assigned to the UE by the MN;

[0047] The identifier assigned to the UE by the source SN during the SN change process. This identifier can be a C-RNTI.

[0048] The types of SCG wireless connection failures can be SN change failure or radio link failure.

[0049] The cell identifier of the PSCell of the source SN that the SN changes may optionally include the TAC and PLMN identifiers, or TAI, to which the cell belongs;

[0050] The cell identifier of the PSCell of the SN where the SCG wireless connection failure occurred may optionally include the TAC and PLMN identifiers, or TAI, to which the cell belongs.

[0051] The cell identifier of a cell of a suitable SN to access after a wireless connection failure may optionally include the TAC and PLMN identifiers, or TAI, to which the cell belongs.

[0052] The interval between the last SN change process and the SCG wireless connection failure;

[0053] Information list of SNs to which the UE is connected, or UE history information containing information list of SNs to which the UE is connected;

[0054] Mobility Information.

[0055] Using this method, the node that receives the handover report can determine the type of SN change failure based on the received information and / or the saved information, such as the list of SNs to which the UE is connected, and optimize the parameters used to generate the SN change decision to reduce or avoid similar errors from happening again.

[0056] According to another aspect of the embodiments of this disclosure, a self-optimizing method for auxiliary node changes is provided.

[0057] The UE can establish a radio connection with both MN and SN1 simultaneously, and either MN or SN1 can decide whether to initiate an SN change; that is, either MN or SN1 can trigger the SN change process.

[0058] If a subsequent SN change occurs, SN1 will be the source SN for the change. For potential SN change failures, the source SN is one piece of information used to determine the type of failure. This information can be obtained either by the UE reporting it in an RRC message, or by the MN retrieving it from the SN and storing it on the MN when configuring the SN for the UE. In the latter case, the MN can add the SN1 information to the list of SNs connected to the UE in the UE History Information stored on the MN. This list can include information about one or more SNs connected to the UE. The information about the SN connected to the UE can be the SN's identification information, and / or the duration of the UE's connection to the SN, and / or the reason the UE's SN was configured as that SN, and / or the information of the MN associated with that SN. The SN's identification information includes the cell identifier of the primary / secondary cell (PSCell), and optionally, it can also include the Tracking Area Code (TAC) and PLMN identifier, or Tracking Area Identifier (TAI), and / or the SN's node ID. The information of the MN may be the PCell ID, and / or the TAC and PLMN identifier to which the Cell belongs, or the TAI, and / or the node ID of the MN. Optionally, the MN may save the list as a separate information section instead of adding it to the UE history information.

[0059] If MN or SN1 fails to initiate the SN change procedure from SN1 to SN2 as required, the UE will experience a radio connection failure on SN1; or if MN or SN1 decides to initiate the SN change procedure from SN1 to SN2 at an inopportune time, the UE will experience a radio connection failure on SN2 during the SN change procedure or shortly after the SN change procedure is successfully completed.

[0060] If the MN or SN1 initiates an SN change process from SN1 to SN2, SN2 is the target SN for the SN change. In the event of a potential SN change failure, SN2 will be the SN where the SCG radio connection failure occurred. The SN where the SCG radio connection failure occurred is one of the pieces of information used to determine the type of SN change failure. This information can be obtained either by the UE reporting it in an RRC message, or by the MN retrieving it from the SN and storing it on the MN when configuring the SN for the UE. In the latter case, the MN adds the information of SN2 to the saved list of SNs connected to the UE, as described above.

[0061] The UE sends a secondary cell group (SCG) failure message to the MN. This message includes one or more combinations of the following:

[0062] The cell identifier of the PSCell of the SN where the SCG wireless connection failure occurred may optionally include the TAC and PLMN identifiers, or TAI, to which the cell belongs.

[0063] The cell identifier of the PSCell of the source SN during the last SN change process may optionally include the TAC and PLMN identifiers, or TAI, to which the cell belongs;

[0064] The cell identifier of a cell of an SN suitable for UE access after the UE reports an SCG failure. Optionally, it may also include the TAC and PLMN identifiers of the cell, or TAI;

[0065] The interval between the last SN change process and the SCG radio connection failure can be the time from when the UE received the RRC reconfiguration message containing SN change information to the SCG failure or the time from when the UE sent the SN reconfiguration completion message to the SCG failure.

[0066] The types of SCG wireless connection failures can be SN change failure or radio link failure.

[0067] The identifier C-RNTI assigned to the UE by the SN when an SCG radio connection failure occurs;

[0068] The identifier C-RNTI assigned to the UE by the source SN during the last SN change process;

[0069] The identifier C-RNTI assigned by the MN to the UE;

[0070] UE measurement report.

[0071] The interval between the last SN change process and the SCG radio connection failure is one of the pieces of information used to determine the type of SN change failure. The MN can also calculate the interval between the last SN change process and the SCG radio connection failure based on the time of the last SN change process (which could be the time the MN sent the last RRC reconfiguration message containing SN change information or the time the MN received the SN reconfiguration completion message) and the time it received the SCG failure information from the UE. The type of SCG radio connection failure is also one of the pieces of information used to determine the type of SN change failure. The MN can also determine the type of SCG radio connection failure based on whether the SN change process was successfully completed. For example, if the SN change process was successfully completed, the MN can determine that the SCG radio connection failure is a radio link failure; otherwise, the MN can determine that the SCG radio connection failure is an SN change failure.

[0072] The appropriate access cell can be sent by the UE to the MN, which in turn sends it to the SN; it can also be determined by the SN based on the UE's measurement report; or it can be a cell on another SN that the MN decides to configure for the UE, which is then sent to the SN by the MN.

[0073] The appropriate SN cell for access is one of the pieces of information used to determine the type of SN change failure. The MN can add the information of the new SN selected for the UE to the saved list of SNs connected to the UE. As mentioned above, the information of the new SN includes the cell identifier of the cell to which the SN belongs, and optionally, it may also include the TAC and PLMN identifiers, or TAI, of the cell, and / or the node ID of the SN. If the SN change is too late, the appropriate SN for access can be SN2; if the SN change is too early, the appropriate SN for access can be SN1; if the change is to the wrong SN cell, the appropriate SN for access can be SN3.

[0074] The MN can determine the cause of the failure based on the SCG failure information or the UE context information it saves. The cause of the failure includes changing the SN too late, changing the SN too early, or changing to the wrong SN cell.

[0075] If the UE camps on the cell of the SN where the SCG radio connection failure occurred for a long time (without a recent SN change), and the UE had a suitable cell on another SN for access when the SCG failure occurred, then the SN change was too late. The suitable cell on the other SN can be one sent by the UE to the MN, determined by the MN based on the UE's measurement report, or a cell on another SN that the MN decides to configure for the UE. The MN knows whether there has been a recent SN change based on the interval between the last received SN change process and the SCG radio connection failure, or based on the time difference between the last transmission of UE context release to the source SN and the failure indication.

[0076] If the SN change is too late, the MN knows that it or the SN experiencing SCG radio connection failure should trigger an SN change process, but neither occurs, leading to UE failure on the SN. Therefore, both the MN and the SN experiencing SCG radio connection failure are problematic nodes. The MN can perform appropriate self-optimization. The MN sends a handover report message to the SN experiencing SCG radio connection failure. The handover report can also be an SCG handover report or other messages, including the message indicating that the SN change was too late. This message includes the cell identifier of the UE's PSCell on the SN experiencing SCG radio connection failure, and / or the cell identifier of a cell on a suitable SN for UE access.

[0077] Based on information received from the UE or stored UE context information, if the UE recently underwent a SN change, and the SN of the source cell of the SN change is a suitable SN for UE access after a failure, or if the source cell of the SN change is a suitable SN for UE access after a failure, then the SN change was too early. The MN determines whether there has been a recent SN change based on the interval between the received last SN change process and the SCG radio connection failure, or based on the time difference between the last transmission of UE context release to the source SN and the failure indication. The MN determines the source cell identifier of the last SN change based on the source cell identifier carried in the SCG failure information or based on the stored UE context. The suitable cell for UE access after a failure can be a cell sent by the UE to the MN, determined by the MN based on the UE's measurement report, or a cell on another SN that the MN decides to configure for the UE.

[0078] If the SN change occurred too early, and the SN change was initiated by the MN before the failure, the MN can perform appropriate self-optimization. The MN knows whether the SN change was initiated by the MN or the SN before the failure based on the saved UE context information. If the SN change was initiated by the SN before the failure, the MN sends a handover report message to the source SN of the SN change. The handover report can also be an SCG handover report or other messages containing the message "SN change too early," and the message includes the cell identifier of the PSCell of the SN where the SCG radio connection failure occurred and / or the PSCell cell identifier of the source SN.

[0079] Based on information received from the UE or stored UE context information, if the UE has recently undergone a SN change, and the suitable SN cell for UE access after a failure is neither the source SN of the previous SN change, nor the SN cell where the failure occurred, nor the destination SN cell of the SN change, then the MN has changed to an incorrect SN cell. The MN determines whether there has been a recent SN change based on the interval between the received information about the previous SN change and the SCG radio connection failure, or based on the time difference between the last transmission of UE context to the source SN and the failure indication. The MN determines the source cell identifier of the previous SN change based on the source cell identifier carried in the SCG failure information or based on the stored UE context. The suitable cell for UE access after a failure can be one sent by the UE to the MN, determined by the MN based on the UE's measurement report, or a cell on another SN that the MN decides to configure for the UE.

[0080] For a change to an incorrect SN cell, if the SN change was initiated by the MN before the failure occurred, the MN can perform appropriate self-optimization. The MN knows whether the SN change was initiated by the MN or the SN before the failure based on the saved UE context information. If the SN change was initiated by the SN before the failure, the MN sends a handover report message to the source SN of the SN change. The handover report can also be an SCG handover report or other messages, containing information about the incorrect SN change. This message includes the cell identifier of the PSCell of the SN where the SCG radio connection failure occurred, the PSCell cell identifier of the source SN, and / or the cell identifier of a cell on an SN suitable for UE access.

[0081] The node receiving the handover report can determine the type of SN change failure based on the received information and / or stored information such as the list of SNs to which the UE is connected, and optimize the parameters used to generate the SN change decision to reduce or avoid similar errors from recurring. The node receiving the handover report can be the MN or the source SN of the SN change.

[0082] According to another aspect of the embodiments of this disclosure, a self-optimizing method for auxiliary node changes is provided.

[0083] The UE can establish a radio connection with both MN and SN1 simultaneously, and either MN or SN1 can decide whether to initiate an SN change; that is, either MN or SN1 can trigger the SN change process.

[0084] During SN changes, it is beneficial for the MN to store information about the SN to which the UE is connected. However, in traditional methods, the MN must actively request this information from the SN, or the SN must actively submit this information to the MN. Therefore, if the MN neither requests nor provides this information to the SN, the MN may lack information about the SN to which the UE is connected, such as the PSCell selected by the SN. Therefore, a method is needed that allows the MN to always obtain and retain the PSCell selected by the SN from, for example, the SN where the SCG radio connection failed or the source SN where the SN changed.

[0085] During the process of MN configuring SN1 as the UE's SN, in the secondary node add request message, MN can always request the configured SN to report the information of the PSCell selected by that SN, regardless of whether MN is configured to request the SN to report this information. The information includes the cell identifier and the PLMN identifier of the cell.

[0086] During the process of the MN configuring SN1 as the UE's SN, in the request confirmation message added to the secondary node, the configured SN always reports the information of the PSCell selected by the SN to the MN, regardless of whether the MN requests the SN to report this information. The information includes the cell identifier and the PLMN identifier of the cell.

[0087] The MN can add the information of SN1 to the saved list of information of the SN to which the UE is connected, as described above.

[0088] If the UE experiences an SCG radio connection failure on SN1, the MN can configure SN2 as the UE's new SN; or the MN or SN1 can initiate a SN change process from SN1 to SN2, in which case the MN can configure SN2 as the UE's new SN. During this process, the MN may always request the configured SN to report the PSCell information selected by that SN, or the configured SN may always report the PSCell information selected by that SN to the MN; further details are omitted here.

[0089] The MN can add the information of SN2 to the information list of the SNs connected to the UE, as described above.

[0090] If MN or SN1 fails to initiate the SN change procedure from SN1 to SN2 as required, the UE will experience a radio connection failure on SN1; or if MN or SN1 decides to initiate the SN change procedure from SN1 to SN2 at an inopportune time, the UE will experience a radio connection failure on SN2 during the SN change procedure or shortly after the SN change procedure is successfully completed.

[0091] The UE sends SCG failure information to the MN. The MN can send a failure indication message to the SN where the SCG radio connection failed, and the SN can send a handover report message to the node that decided to change the SN; or the MN can send a handover report message to the node that decided to change the SN. The MN, the SN where the SCG radio connection failed, or the node that decided to change the SN can use the information reported by the UE, and / or its own stored information such as the information list of the SNs to which the UE is connected, to determine the type of SN change failure. The process can be similar to any of the aforementioned methods, and will not be described in detail here.

[0092] In existing mechanisms, the PSCell information reported by the SN to the MN is only used as the UE's location information. In this embodiment, the PSCell information selected by the SN reported by SN1 or SN2 to the MN can also be used as information of the source SN that the SN changed, or information of the SN that experienced SCG radio connection failure, to determine the type of SN change failure, and ultimately for network self-configuration and self-optimization.

[0093] Using this method, the node that receives the handover report can determine the type of SN change failure based on the received information and / or the saved information, such as the list of SNs to which the UE is connected, and optimize the parameters used to generate the SN change decision to reduce or avoid similar errors from happening again.

[0094] According to another aspect of the embodiments of this disclosure, a self-optimizing method for auxiliary node changes is provided.

[0095] The UE can establish a radio connection with both MN and SN1 simultaneously, and either MN or SN1 can decide whether to initiate an SN change; that is, either MN or SN1 can trigger the SN change process.

[0096] The steps before the SN experiencing SCG radio connection failure sends a message to the node initiating the SN change are similar to the methods described above. The SN experiencing SCG radio connection failure can send a handover report to the node initiating the SN change for analysis and optimization of the parameters that led to the SN change decision. If the node initiating the SN change is the MN, the message is similar to that described in the methods described above.

[0097] If the node initiating the SN change is the source SN of the SN change, the SN that experiences SCG radio connection failure can always send a handover report to the source SN via the MN, or send a handover report to the source SN via the MN if there is no lateral interface (such as X2, Xn or other base station interfaces) between the source SN and the SN where the failure occurred.

[0098] The switching report can also be an SCG switching report or other messages.

[0099] The message contains one or more combinations of the following information:

[0100] The SCG failure information;

[0101] The types of SN change failures can be SN change too late, SN change too early, or SN change to the wrong cell.

[0102] The identifier assigned to the UE by the MN;

[0103] The identifier assigned to the UE by the source SN during the SN change process. This identifier can be a C-RNTI.

[0104] The types of SCG wireless connection failures can be SN change failure or radio link failure.

[0105] The cell identifier of the PSCell of the source SN that the SN changes may optionally include the TAC and PLMN identifiers, or TAI, to which the cell belongs;

[0106] The cell identifier of the PSCell of the SN where the SCG wireless connection failure occurred may optionally include the TAC and PLMN identifiers, or TAI, to which the cell belongs.

[0107] The cell identifier of a cell of an SN suitable for access after a wireless connection failure may optionally include the TAC and PLMN identifiers, or TAI, to which the cell belongs.

[0108] The interval between the last SN change process and the SCG wireless connection failure;

[0109] Information list of SNs to which the UE is connected, or UE history information containing information list of SNs to which the UE is connected;

[0110] Mobility Information.

[0111] Using this method, the node that receives the handover report can determine the type of SN change failure based on the received information and / or the saved information, such as the list of SNs to which the UE is connected, and optimize the parameters used to generate the SN change decision to reduce or avoid similar errors from happening again.

[0112] According to another aspect of the embodiments of this disclosure, a self-optimizing method for auxiliary node changes is provided.

[0113] The UE can establish a radio connection with both MN and SN1 simultaneously, and either MN or SN1 can decide whether to initiate an SN change; that is, either MN or SN1 can trigger the SN change process.

[0114] The steps before the SN that experiences SCG radio connection failure sends a message to the node that initiated the SN change are similar to the methods described above. The SN that experiences SCG radio connection failure can send a message to the node that decided on the SN change, allowing it to analyze and optimize the parameters that led to the SN change decision. If the node that initiated the SN change is the MN, the message is similar to that described in the methods described above.

[0115] If the node initiating the SN change is the source SN of the SN change, and there is no lateral interface (such as X2, Xn, or other inter-base station interface) between the SN experiencing the SCG radio connection failure and the source SN, the SN experiencing the SCG radio connection failure sends an uplink radio access network (RAN) configuration transfer message to the core network entity. This message includes the type of SN change failure, and also includes the cell identifier of the PSCell of the SN experiencing the SCG radio connection failure, the cell identifier of the source SN's PSCell, and / or the cell identifier of the cell on the SN suitable for UE access. The message also includes the TAC and PLMN identifiers of the cell of the SN experiencing the SCG radio connection failure's PSCell, or the TAI of the cell of the SN experiencing the SCG radio connection failure's PSCell, the TAC and PLMN identifiers of the source SN's PSCell, or the TAI of the source SN's PSCell. The TAC and PLMN identifiers, or the TAI, are used for routing in the core network, such as when the core network entity to which the SN experiencing the SCG radio connection failure is connected finds the core network entity to which the source SN is connected. The core network entity then sends a downlink RAN ​​configuration transfer message to the source SN. The message includes the type of SN change failure, and also includes the cell identifier of the PSCell of the SN where the SCG radio connection failure occurred, the PSCell cell identifier of the source SN, and / or the cell identifier of a cell on the SN suitable for UE access.

[0116] The uplink RAN ​​configuration transfer message and the downlink RAN ​​configuration transfer message may also include one or more combinations of the following information:

[0117] The SCG failure information;

[0118] The node information of the source SN includes one or more combinations of the following:

[0119] The node ID of the node may optionally include the TAC and PLMN identifiers to which the node belongs, or the TAI;

[0120] The cell identifier of the PSCell of the SN may optionally include the TAC and PLMN identifiers to which the cell belongs, or the TAI.

[0121] The types of SN change failures can be SN change too late, SN change too early, or SN change to the wrong cell;

[0122] The identifier assigned to the UE by the source SN during the SN change process. This identifier can be a C-RNTI.

[0123] The identifier assigned to the UE by the MN;

[0124] The types of SCG wireless connection failures can be SN change failure or radio link failure.

[0125] The cell identifier of the PSCell of the source SN that the SN changes may optionally include the TAC and PLMN identifiers, or TAI, to which the cell belongs;

[0126] The cell identifier of the PSCell of the SN where the SCG wireless connection failure occurred may optionally include the TAC and PLMN identifiers, or TAI, to which the cell belongs.

[0127] The cell identifier of a cell of an SN suitable for access after a wireless connection failure may optionally include the TAC and PLMN identifiers, or TAI, to which the cell belongs.

[0128] The interval between the last SN change process and the SCG wireless connection failure;

[0129] Information list of SNs to which the UE is connected, or UE history information containing information list of SNs to which the UE is connected;

[0130] Mobility Information.

[0131] Using this method, the node receiving the message can determine the type of SN change failure based on the received information and / or the saved information, such as the information list of the SN to which the UE is connected, and optimize the parameters used to generate the SN change decision to reduce or avoid similar errors from happening again.

[0132] When determining the type of SN failure, MN and SN primarily rely on the following information: the source SN information of the SN change, the SN information of the SN where the SCG radio connection failure occurred, the suitable SN information for configuration, the interval between the last SN change process and the SCG radio connection failure, the type of SCG radio connection failure, and / or the UE's measurement report. The interval between the last SN change process and the SCG radio connection failure can be the interval between the initiation time of the last SN change process and the SCG radio connection failure, or the interval between the successful completion of the last SN change process and the SCG radio connection failure. This information can be obtained in two ways: one is through the UE reporting to the network, and the other is through the network maintaining the UE's context information. Only one method can be used, or both methods can be used simultaneously.

[0133] According to various embodiments of this disclosure, the types of SN change failures can also be SN change too late, SN change too early, SN change to the wrong cell, or SN change ping-pong.

[0134] According to various embodiments of this disclosure, the MN and SN may be base stations.

[0135] According to another aspect of the embodiments of this disclosure, a self-optimizing method for auxiliary node changes is provided.

[0136] The UE can maintain a radio connection with both the MN and the SN simultaneously. While the UE maintains a radio connection with the MN, the SN can decide to change the UE's PSCell, for example, changing the PSCell from cell 1 to cell 2, where cell 1 and cell 2 can belong to the same SN. The SN can generate a list of PSCell information that the UE has connected to. The list can include information about one or more PSCells that the UE has connected to. The information can include at least one of the following: the identification information of the SN to which the PSCell belongs, the duration of the UE's connection to the PSCell, the reason for the change of the PSCell, and the associated MN identification information. The SN identification information can include the PSCell ID, and optionally, it can also include the TAC and PLMN identifiers, or TAI, to which the cell belongs, and / or the SN's node ID. The MN identification information can be the PCell ID, and optionally, it can also include the TAC and PLMN identifiers, or TAI, to which the cell belongs, and / or the MN's node ID.

[0137] During the connection maintenance between the UE and the MN, the UE may connect to one or more SNs. Each SN can send a list of PSCell information generated by the SN to the MN. The MN stores the received PSCell information list. The MN can determine whether the PSCell change was initiated by the MN or the SN to which the PSCell belongs, based on the signaling process that occurs when the PSCell changes. The MN also stores the result of this determination.

[0138] The MN can determine whether an SN change ping-pong has occurred based on the above information. For example, if the MN finds from the received PSCell information list that the PSCell connected to the UE changes from Cell 1 to Cell 2 and then from Cell 2 back to Cell 1, and the duration of the UE's connection to Cell 2 is less than a pre-set threshold, the MN can determine that an SN change ping-pong has occurred.

[0139] If the MN learns from the stored information that the process of the UE's connected PSCell changing from Cell 1 to Cell 2 was initiated by the SN to which Cell 1 belongs, the MN can send the SN a determination that an SN Change Ping-pong has occurred, and / or a list of PSCell information received by the MN. The SN can determine whether an SN Change Ping-pong has occurred based on the list of PSCell information, or it can directly adopt the MN's determination, thereby optimizing the parameters used to generate the SN change decision and reducing or avoiding similar errors from recurring.

[0140] If the MN learns from the saved information that the process of changing the PSCell connected to the UE from Cell 1 to Cell 2 was initiated by the MN, the MN can optimize the parameters used to generate the SN change decision to reduce or avoid similar errors from happening again.

[0141] According to another aspect of the embodiments of this disclosure, a self-optimizing method for auxiliary node changes is provided.

[0142] The UE can establish radio connections with both MN1 and SN1 simultaneously. MN1 decides to initiate a handover procedure to MN2. MN2 decides to configure SN2 as the UE's SN. Subsequently, MN1 releases SN1. SN1 and SN2 can be the same or different.

[0143] SN1 can generate a list of PSCell information that the UE has connected to. The list may include information about one or more PSCells that the UE has connected to. The information may include at least one of the following: the identification information of the SN to which the PSCell belongs, the duration of the UE's connection to the PSCell, the reason for the PSCell being changed, and / or the identification information of the associated MN. The SN identification information may include the PSCell ID, and optionally, may also include the TAC and PLMN identifiers, or TAI, to which the cell belongs, and / or the node ID of the SN. The MN identification information may be a PCell ID, and optionally, may also include the TAC and PLMN identifiers, or TAI, to which the cell belongs, and / or the node ID of the MN. SN1 sends the list of PSCell information that the UE has connected to to MN1.

[0144] MN1 can send the list of PSCell information that the UE has connected to to MN2.

[0145] During the process of the UE connecting to MN2, the UE may connect to one or more SNs. Each SN can send a list of PSCell information generated by that SN to MN2. MN2 stores the received list of PSCell information.

[0146] MN2 can determine whether an SN Change Ping-pong has occurred based on the above information. For example, based on the received PSCell information list, MN2 finds that the PSCell connected to the UE changes from Cell 1 of SN1 (when the UE was also connected to MN1) to Cell 2 of SN2 (when the UE was also connected to MN2), and then changes from Cell 2 back to Cell 1 of SN1 (when the UE was also connected to MN2), and the duration of the UE's connection to Cell 2 is less than a pre-set threshold. MN2 can then determine that an SN Change Ping-pong has occurred.

[0147] Since the process of configuring SN2 as the UE's SN is initiated by MN2, MN2 can optimize the parameters used to generate the SN change decision to reduce or avoid similar errors from happening again.

[0148] According to embodiments of the present disclosure, a first node in a wireless communication system is provided, wherein the first node can perform at least one of the above-described methods.

[0149] According to embodiments of the present disclosure, a second node in a wireless communication system is provided, wherein the second node can perform at least one of the above-described methods.

[0150] According to embodiments of this disclosure, a node in a wireless communication system is provided that triggers a change in the serial number (SN), wherein the node triggering the SN change can perform at least one of the methods described above.

[0151] According to embodiments of this disclosure, a self-optimizing system in a wireless communication system is provided. The self-optimizing system may include: a first node; a second node; and a node that triggers a change in the serial number (SN), wherein the first node, the second node, and the node that triggers the SN change can perform at least one of the above-described methods.

[0152] The above and other features, aspects, and advantages of the various embodiments of this disclosure will be better understood by referring to the following description and the appended claims. The accompanying drawings, which form part of this disclosure, illustrate exemplary embodiments of the disclosure and, together with the description, serve to explain the relevant principles. Details of one or more embodiments of the subject matter of the invention are set forth in the accompanying drawings and the following description. Other potential features, aspects, and advantages of the subject matter of the invention will also become clear from these descriptions, drawings, and claims. Attached Figure Description

[0153] In the following description, with reference to the accompanying drawings, a detailed description and discussion of one or more embodiments of the subject matter of the invention are set forth to those skilled in the art, wherein:

[0154] Figure 1 This is a schematic diagram showing the UE establishing wireless connections with two access nodes simultaneously;

[0155] Figure 2 This is a schematic diagram illustrating the UE switching from one secondary node to another.

[0156] Figure 3 This is a flowchart illustrating a self-optimization method according to an example embodiment of the present disclosure;

[0157] Figure 4 This is a flowchart illustrating a self-optimization method according to an example embodiment of the present disclosure;

[0158] Figure 5 This is a flowchart illustrating a self-optimization method according to an example embodiment of the present disclosure;

[0159] Figure 6 This is a flowchart illustrating a self-optimization method according to an example embodiment of the present disclosure;

[0160] Figure 7 This is a flowchart illustrating a self-optimization method according to an example embodiment of the present disclosure;

[0161] Figure 8 This is a flowchart illustrating a self-optimization method according to an example embodiment of the present disclosure;

[0162] Figure 9 This is a flowchart illustrating a self-optimization method according to an example embodiment of the present disclosure;

[0163] Figure 10 An embodiment according to this disclosure is illustrated schematically;

[0164] Figure 11 Embodiment 2 according to this disclosure is illustrated schematically;

[0165] Figure 12 Embodiment 3 according to this disclosure is illustrated schematically;

[0166] Figure 13 Embodiment four according to this disclosure is illustrated schematically;

[0167] Figure 14 Embodiment five according to this disclosure is illustrated schematically;

[0168] Figure 15 Embodiment six according to this disclosure is illustrated schematically;

[0169] Figure 16 Embodiment seven according to this disclosure is illustrated schematically;

[0170] Figure 17 Embodiment eight according to this disclosure is illustrated schematically;

[0171] Figure 18 Embodiment nine according to the present disclosure is illustrated schematically;

[0172] Figure 19 Embodiment ten according to this disclosure is illustrated schematically;

[0173] Figure 20 Embodiment eleven according to this disclosure is illustrated schematically;

[0174] Figure 21 Embodiment twelve according to this disclosure is illustrated schematically;

[0175] Figure 22 Embodiment thirteen according to this disclosure is illustrated schematically;

[0176] Figure 23 Embodiment fourteen according to this disclosure is illustrated schematically;

[0177] Figure 24 Embodiment fifteen according to this disclosure is illustrated schematically;

[0178] Figure 25 Embodiment sixteen according to this disclosure is illustrated schematically;

[0179] Figure 26schematically shown Figure 19 Another implementation of Example 10;

[0180] Figure 27 schematically shown Figure 19 Another implementation of Example 10;

[0181] Figure 28 schematically shown Figure 25 Another implementation of Example Sixteen;

[0182] Figure 29 schematically shown Figure 19 Another implementation of Example 10;

[0183] Figure 30 schematically shown Figure 22 Another implementation of Example Thirteen;

[0184] Figure 31 Embodiment fourteen according to this disclosure is illustrated schematically;

[0185] Figure 32 Embodiment fifteen according to this disclosure is schematically illustrated; and

[0186] Figure 33 A block diagram of an access node according to an exemplary embodiment of the present disclosure is schematically shown. In the various figures, the same or similar reference numerals and designations indicate the same or similar elements. Detailed Implementation

[0187] Definitions of certain words and terms are given in the description of this disclosure. Those skilled in the art will understand that, in many cases (if not in most), such definitions apply to the use of such words and terms in various past and future contexts. Unless otherwise expressly stated, the terms used in this disclosure have the same meaning as understood by those skilled in the art to which this disclosure pertains. For example, terms defined in commonly used dictionaries should be interpreted as having the same meaning as their contextual meaning in the relevant field and should not be interpreted as having an overly idealized or formalized meaning.

[0188] Although ordinal terms such as “first” and “second” are used to describe various elements (e.g., components, steps, etc.), these elements are not limited by these terms. These terms are only used to distinguish one element from another. Therefore, these terms may be used interchangeably without departing from the scope of this disclosure. For example, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element. Furthermore, as used herein, the terms “ / ”, “or”, and “and / or” are intended to include any and all combinations of one or more related matters.

[0189] The aspects and features of this disclosure, as well as its implementation, can be more clearly understood by referring to the following detailed description of various embodiments and the accompanying drawings. However, this disclosure may be embodied in many different forms and should not be construed as limited to the various embodiments set forth herein. Rather, these embodiments are provided to make this disclosure sufficient and complete, and to fully convey the principles and concepts of this disclosure to those skilled in the art. Therefore, those skilled in the art will recognize that various modifications, adjustments, combinations, and substitutions can be made to the various embodiments described in this disclosure without departing from the spirit and scope of this disclosure. Furthermore, these modifications, adjustments, combinations, and substitutions should also be considered to be included within the scope of protection of this application as defined by the claims.

[0190] Figure 2 This is a schematic diagram illustrating a UE switching from one secondary node to another. Figure 2 The diagram shows the primary node (not shown in the core network), secondary node 1 (SN1), secondary node 2 (SN2), and user equipment (UE). Figure 2 As shown, the UE's secondary node can be changed from secondary node 1 to secondary node 2. During such a secondary node change, a change failure may occur, i.e., SN change failure. Therefore, notifying the node on which the radio connection failure occurred of the SN change information, judging and identifying the cause or type of SN change failure, and reporting this information to the node that initiated the SN change for reasonable self-optimization are of positive significance for avoiding similar failures in the future and improving the user experience of the UE.

[0191] Figure 3 This is a flowchart illustrating a self-optimization method according to an example embodiment of the present disclosure.

[0192] As shown in the figure, the first node can be MN, the second node can be the SN where the SCG wireless connection failed, and the third node can be the source SN of the last SN change before the failure. Detailed descriptions of some steps that might obscure the subject matter of this invention are omitted here. The method includes the following steps:

[0193] Step 301: The UE sends a secondary cell group (SCG) failure message to the first node.

[0194] The SCG failure information includes one or more combinations of the following:

[0195] The cell identifier of the PSCell of the SN where the SCG wireless connection fails may optionally include the Tracking Area Code (TAC) and PLMN identifier, or Tracking Area Identifier (TAI) to which the cell belongs.

[0196] The cell identifier of the PSCell of the source SN during the last SN change process may optionally include the TAC and PLMN identifiers of the cell, or TAI;

[0197] The cell identifier of a cell of an SN suitable for UE access after the UE reports an SCG failure. Optionally, it may also include the TAC and PLMN identifiers, or TAI, to which the cell belongs.

[0198] The time interval between the last SN change process and the SCG radio connection failure; the time interval may be the time from when the UE received the RRC reconfiguration message containing SN change information to the SCG failure or the time from when the UE sent the SN reconfiguration completion message to the SCG failure.

[0199] The types of SCG wireless connection failures can be SN change failure or radio link failure.

[0200] The identifier C-RNTI assigned to the UE by the SN when an SCG radio connection failure occurs;

[0201] The identifier C-RNTI assigned by the MN to the UE;

[0202] UE measurement report.

[0203] After receiving the information, the first node can reconfigure a new SN for the UE.

[0204] Step 302: The first node sends a failure indication message to the second node. The failure indication message can also be a secondary cell group (SCG) failure indication or other messages, used to send SCG failure information to the second node. The second node can be the SN where the SCG radio connection failure occurred. The first node knows the SN where the SCG radio connection failure occurred based on the SCG failure information received from the UE, or it can also know the SN where the SCG radio connection failure occurred based on information stored in the UE context.

[0205] The message contains a report of SCG failure received from the UE, with specific information as described in step 301. The message also includes information on whether the previous SN change process was triggered by the MN or the SN.

[0206] The message may also contain one or more of the following information:

[0207] SCG failure message;

[0208] Information about the source SN from the last SN change, including the cell identifier of the PSCell, and optionally, the TAC and PLMN identifiers, or TAI, to which the cell belongs;

[0209] Information about the SN where the SCG wireless connection failed includes the cell identifier of the PSCell, and optionally, may also include the TAC and PLMN identifiers, or TAI, to which the cell belongs;

[0210] After the SCG radio connection fails, the cell identifier of a cell suitable for configuring the SN for the UE may optionally include the TAC and PLMN identifiers, or TAI, to which the cell belongs.

[0211] The interval between the last SN change process and the SCG wireless connection failure.

[0212] The identifier assigned to the UE by the SN when the SCG radio connection fails. This identifier can be the S-NG-RAN node UE XnAP ID in the Xn message or the SgNB UE X2AP ID in the X2 message, or it can be C-RNTI;

[0213] The identifier assigned to the UE by the MN. This identifier can be the M-NG-RAN node UE XnAP ID in the Xn message or the MeNB UE X2AP ID in the X2 message, or it can be a C-RNTI;

[0214] The types of SCG wireless connection failures can be SN change failure or radio link failure.

[0215] Information list of SNs to which the UE is connected, or UE history information containing information list of SNs to which the UE is connected;

[0216] Mobility Information.

[0217] Step 303: The second node determines the cause of the failure. The cause of failure includes changing the SN too early, changing the SN too late, or changing to the wrong SN cell.

[0218] Based on the information received in step 302, if the UE has been camped on the cell of the second node for a long time (without recent SN changes), and the UE has a suitable cell on another SN for access when the failure occurs, then the SN change was too late. The suitable cell on another SN for access can be sent by the UE to the first node and then by the first node to the second node, or it can be determined by the second node based on the UE's measurement report, or it can be a cell on another SN that the first node decides to configure for the UE and then sends it to the second node. The second node knows whether there has been a recent SN change based on the interval between the last received SN change process and the SCG radio connection failure, or based on the time difference between the last received SN reconfiguration completion and failure indication.

[0219] If the SN change is too late, the second node can know that it or the MN should have triggered an SN change process, but neither did, leading to the UE's SN failure. Therefore, both the second and first nodes are the nodes causing the problem. The second node can perform appropriate self-optimization. The second node sends a handover report message to the first node. The handover report can also be an SCG handover report or other messages, containing the late SN change information and the cell identifier of the PSCell where the UE failed at the second node.

[0220] Based on the information received in step 302, if the UE has recently undergone a SN change, and the SN of the source cell of the SN change is a suitable SN for UE access after a failure, or if the source cell of the SN change is a suitable SN for UE access after a failure, then the SN change was too early. The second node determines whether there has been a recent SN change based on the interval between the last received SN change process and the SCG radio connection failure, or based on the time difference between the last received SN reconfiguration completion and failure indication. In step 302, the second node receives the source cell identifier of the SN change from the first node. The suitable cell for UE access after a failure can be sent by the UE to the first node and then sent by the first node to the second node, or it can be determined by the second node based on the UE's measurement report, or it can be a cell on another SN that the first node decides to configure for the UE and then sends it to the second node.

[0221] If the SN change is too early, based on whether the most recent SN change was triggered by the MN or the SN received from the first node, for the previous SN change triggered by the MN, the second node sends a handover report message to the first node. The handover report can also be an SCG handover report or other messages, containing the message "SN change too early," and including the cell identifier of the PSCell where the UE failed at the second node. For the previous SN change triggered by the SN, the second node sends a handover report message to the third node, i.e., the source SN. The handover report can also be an SCG handover report or other messages, containing the message "SN change too early," and including the cell identifier of the PSCell where the UE failed at the second node and / or the PSCell cell identifier of the source SN.

[0222] Based on the information received in step 302, if the UE recently underwent a SN change, and the suitable SN cell for UE access after the failure is neither the source SN of the previous SN change nor the SN cell where the failure occurred or the destination SN cell of the SN change, then it has changed to an incorrect SN cell. The second node determines whether there has been a recent SN change based on the interval between the received information about the previous SN change process and the SCG radio connection failure, or based on the time difference between the previously received SN reconfiguration completion and failure indication. In step 302, the second node received the source cell identifier of the SN change from the first node. The suitable cell for UE access after the failure can be sent by the UE to the first node and then by the first node to the second node, or it can be determined by the second node based on the UE's measurement report, or it can be a cell on another SN that the first node decides to configure for the UE and then sends it to the second node.

[0223] For a change to an incorrect SN cell, based on whether the most recent SN change received from the first node was triggered by the MN or the SN, the second node sends a handover report message to the first node for the previous SN change triggered by the MN. The handover report can also be an SCG handover report or other messages. These messages include the cell identifier of the PSCell where the UE failed at the second node, the PSCell cell identifier of the source SN, and / or the PSCell cell identifier on the SN suitable for UE access. For the previous SN change triggered by the SN, the second node sends a handover report message to the third node, i.e., the source SN. The handover report can also be an SCG handover report or other messages. These messages include the cell identifier of the PSCell where the UE failed at the second node, the PSCell cell identifier of the source SN, and / or the PSCell cell identifier on the SN suitable for UE access.

[0224] The message may also contain a combination of one or more of the following information:

[0225] SCG failure message;

[0226] The types of SN change failures can be SN change too late, SN change too early, or SN change to the wrong cell;

[0227] The identifier assigned to the UE by the SN when the SCG radio connection fails. This identifier can be the S-NG-RAN node UE XnAP ID in the Xn message or the SgNB UE X2AP ID in the X2 message, or it can be C-RNTI;

[0228] The identifier assigned to the UE by the MN. This identifier can be the M-NG-RAN node UE XnAP ID in the Xn message or the MeNB UE X2AP ID in the X2 message, or it can be a C-RNTI;

[0229] The types of SCG wireless connection failures can be SN change failure or radio link failure.

[0230] The cell identifier of the PSCell of the source SN that the SN changes may optionally include the TAC and PLMN identifiers, or TAI, to which the cell belongs;

[0231] The cell identifier of the PSCell of the SN where the SCG wireless connection failure occurred may optionally include the TAC and PLMN identifiers, or TAI, to which the cell belongs.

[0232] The cell identifier of a cell of an SN suitable for access after the SCG wireless connection fails. Optionally, it may also include the TAC and PLMN identifiers, or TAI, to which the cell belongs.

[0233] The interval between the last SN change process and the SCG wireless connection failure;

[0234] Information list of SNs to which the UE is connected, or UE history information containing information list of SNs to which the UE is connected;

[0235] Mobility Information.

[0236] The node receiving the handover report can determine the type of SN change failure based on the received information and / or stored information such as the list of SNs to which the UE is connected, and optimize the parameters used to generate the SN change decision to reduce or avoid similar errors from recurring. The node receiving the handover report can be either the first or third node.

[0237] Figure 4 This is a flowchart illustrating a self-optimization method according to an exemplary embodiment of the present disclosure. As shown, the first node can be an MN, the second node can be a SN where an SCG radio connection failure occurs, and the third node can be the source SN of the last SN change before the failure. In this embodiment, the SN where the failure occurred sends a handover report to the source SN via the MN. Detailed descriptions of some steps that may obscure the subject matter of the invention are omitted here. The method includes the following steps:

[0238] Steps 401 to 402 are similar to steps 301 to 302, and will not be described again here.

[0239] Step 403, where the method for determining the failure type in the second node is similar to that in step 303, will not be repeated here. The handling of SN changes being too late is also similar to that described in step 303.

[0240] If the SN change is too early or changes to an incorrect SN cell, the second node sends a handover report message to the first node. The handover report can also be an SCG handover report or other messages. These messages contain information about the incorrect SN change, including the cell identifier of the PSCell where the UE failed at the second node, the PSCell cell identifier of the source SN, and / or the cell identifier of the previous cell on the SN suitable for UE access. For the previous SN change triggered by the SN, the first node sends a handover report message to the third node, i.e., the source SN. These handover reports can also be SCG handover reports or other messages. These messages contain information about the SN change being too early or changing to an incorrect SN cell, including the cell identifier of the PSCell where the UE failed at the second node, the PSCell cell identifier of the source SN, and / or the cell identifier of the previous cell on the SN suitable for UE access.

[0241] The SN where the handover occurred can always send a handover report to the source SN via the MN, or, if there is no lateral interface (such as X2, Xn, or other inter-base station interface) between the source SN and the SN where the handover occurred, send the handover report to the source SN via the MN. If there is a direct lateral interface (such as X2, Xn, or other inter-base station interface) between the source SN and the SN where the handover occurred, send it directly to the third node as described in step 303. The handover report message may also contain one or more of the following information in combination:

[0242] SCG failure message;

[0243] The types of SN change failures can be SN change too late, SN change too early, or SN change to the wrong cell;

[0244] The identifier assigned to the UE by the SN when the SCG radio connection fails. This identifier can be the S-NG-RAN node UE XnAP ID in the Xn message or the SgNB UE X2AP ID in the X2 message, or it can be C-RNTI;

[0245] The identifier assigned to the UE by the source SN during the SN change process. This identifier can be a C-RNTI.

[0246] The identifier assigned to the UE by the MN. This identifier can be the M-NG-RAN node UE XnAP ID in the Xn message or the MeNB UE X2AP ID in the X2 message, or it can be a C-RNTI;

[0247] The types of SCG wireless connection failures can be SN change failure or radio link failure.

[0248] The cell identifier of the PSCell of the source SN that the SN changes may optionally include the TAC and PLMN identifiers, or TAI, to which the cell belongs;

[0249] The cell identifier of the PSCell of the SN where the SCG wireless connection failure occurred may optionally include the TAC and PLMN identifiers, or TAI, to which the cell belongs.

[0250] The cell identifier of a cell of an SN suitable for access after a wireless connection failure may optionally include the TAC and PLMN identifiers, or TAI, to which the cell belongs.

[0251] The interval between the last SN change process and the SCG wireless connection failure;

[0252] Information list of SNs to which the UE is connected, or UE history information containing information list of SNs to which the UE is connected;

[0253] Mobility Information.

[0254] The node receiving the handover report can determine the type of SN change failure based on the received information and / or stored information such as the list of SNs to which the UE is connected, and optimize the parameters used to generate the SN change decision to reduce or avoid similar errors from recurring. The node receiving the handover report can be either the first or third node.

[0255] Figure 5This is a flowchart illustrating a self-optimization method according to an exemplary embodiment of the present disclosure. As shown, the first node can be an MN, the second node can be a SN where an SCG radio connection failure occurs, and the third node can be the source SN of the last SN change before the failure. In this embodiment, the SN where the failure occurred sends a handover report to the source SN through the core network. Detailed descriptions of some steps that may obscure the subject matter of the invention are omitted here. The method includes the following steps:

[0256] Steps 501 to 502 are similar to steps 301 to 302, and will not be described again here.

[0257] Step 503, where the method for determining the failure type of the second node is similar to that in step 303, will not be repeated here. The handling of SN changes that occur too late is also similar to that described in step 303.

[0258] If the SN change triggered by MN is too late, too early, or changes to the wrong SN cell, the second node sends a handover report to the first node. The specifics are similar to those in step 303, and will not be repeated here.

[0259] For the previous SN change triggered by the SN, if there is a lateral interface (such as X2, Xn, or other inter-base station interfaces) between the source SN and the SN where the failure occurred, the SN where the failure occurred directly sends a handover report to the source SN, as described in step 303. If there is no lateral interface (such as X2, Xn, or other inter-base station interfaces) between the source SN and the SN where the failure occurred, the SN where the failure occurred sends an uplink radio access network (RAN) configuration transfer message to the core network entity. The message includes information about whether the SN change was too early or changed to the wrong SN cell. The message also includes the cell identifier of the PSCell where the UE failed at the second node, the PSCell cell identifier of the source SN, and / or the cell identifier of the cell on the SN suitable for UE access. The message also includes the TAC and PLMN identifiers of the PSCell where the UE failed at the second node, or the TAI of the PSCell where the UE failed at the second node, the TAC and PLMN identifiers of the PSCell of the source SN, or the TAI of the PSCell of the source SN. The TAC and PLMN identifiers or TAI are used for routing in the core network, such as when the core network entity connected to the failed SN finds the core network entity connected to the source SN. The core network entity sends a downlink RAN ​​configuration transfer message to the source SN. The message contains erroneous SN changes, and also includes the cell identifier of the PSCell where the UE failed at the second node, the PSCell cell identifier of the source SN, and / or the cell identifier of a cell on the SN suitable for UE access.

[0260] The uplink RAN ​​configuration transfer message and the downlink RAN ​​configuration transfer message may also include one or more combinations of the following information:

[0261] SCG failure message;

[0262] The node information of the SN;

[0263] The node information includes one or more combinations of the following:

[0264] The node ID of the node may optionally include the TAC and PLMN identifiers to which the node belongs, or the TAI;

[0265] The cell identifier of the PSCell of the SN may optionally include the TAC and PLMN identifiers to which the cell belongs, or the TAI.

[0266] The types of SN change failures can be SN change too late, SN change too early, or SN change to the wrong cell;

[0267] The identifier assigned to the UE by the SN when the SCG radio connection fails. This identifier can be the S-NG-RAN node UE XnAP ID in the Xn message or the SgNB UE X2AP ID in the X2 message, or it can be C-RNTI;

[0268] The identifier assigned to the UE by the source SN during the SN change process. This identifier can be a C-RNTI.

[0269] The identifier assigned to the UE by the MN. This identifier can be the M-NG-RAN node UE XnAP ID in the Xn message or the MeNB UE X2AP ID in the X2 message, or it can be a C-RNTI;

[0270] The types of SCG wireless connection failures can be SN change failure or radio link failure.

[0271] The types of SN change failures can be SN change too late, SN change too early, or SN change to the wrong cell;

[0272] The cell identifier of the PSCell of the source SN that the SN changes may optionally include the TAC and PLMN identifiers, or TAI, to which the cell belongs;

[0273] The cell identifier of the PSCell of the SN where the SCG wireless connection failure occurred may optionally include the TAC and PLMN identifiers, or TAI, to which the cell belongs.

[0274] The cell identifier of a cell of an SN suitable for access after a wireless connection failure may optionally include the TAC and PLMN identifiers, or TAI, to which the cell belongs.

[0275] The interval between the last SN change process and the SCG wireless connection failure;

[0276] Information list of SNs to which the UE is connected, or UE history information containing information list of SNs to which the UE is connected;

[0277] Mobility Information.

[0278] The node receiving the handover report or the node receiving the downlink RAN ​​configuration transfer message can determine the type of SN change failure based on the received information and / or the stored information, such as the list of SNs to which the UE is connected, and optimize the parameters used to generate the SN change decision to reduce or avoid similar errors from recurring. The node receiving the handover report can be either the first node or the third node.

[0279] Figure 6 This is a flowchart illustrating a self-optimization method according to an example embodiment of the present disclosure. As shown, the first node can be MN, and the second node can be the SN that triggers the SN change before failure occurs. Detailed descriptions of some steps that may obscure the subject matter of the invention are omitted here. The method includes the steps of:

[0280] Step 601 is similar to step 301, and will not be described again here.

[0281] Step 602: The first node determines the cause of the failure. The causes of failure include changing the SN too late, changing the SN too early, or changing to the wrong SN cell.

[0282] Based on the information received in step 601 or the first node's stored UE context information, if the UE has been camped on the second node's cell for a long time (without recent SN changes), and the UE has a suitable cell on another SN for access when the failure occurs, then the SN change is too late. The suitable cell on another SN can be one sent by the UE to the first node, determined by the first node based on the UE's measurement report, or a cell on another SN that the first node decides to configure for the UE. The first node knows whether there has been a recent SN change based on the interval between the last received SN change process and the SCG radio connection failure, or based on the time difference between the last transmission of UE context release to the source SN and the failure indication.

[0283] If the SN change is too late, the first node knows that it or the SN where the failure occurred should trigger an SN change process, but none of these occur, leading to the UE's SN failure. Therefore, both the first and second nodes are the nodes causing the problem. The first node can perform appropriate self-optimization. The first node sends a handover report message to the second node. The handover report can also be an SCG handover report or other messages, containing the message "SN change too late" and the cell identifier of the PSCell where the UE failed at the second node.

[0284] The first node, based on the information received from the UE in the steps or based on the saved UE context information, determines whether the SN change occurred too early if the UE recently underwent a SN change, and the SN of the source cell of the SN change is a suitable SN for UE access after a failure. The first node determines whether there was a recent SN change based on the interval between the received last SN change process and the SCG radio connection failure, or based on the time difference between the last transmission of UE context release to the source SN and the failure indication. The first node received the source cell identifier of the last SN change in step 601, or knows the source cell identifier of the last SN change based on the saved UE context. The suitable cell for UE access after a failure can be sent by the UE to the first node, determined by the first node based on the UE's measurement report, or a cell on another SN that the first node decides to configure for the UE.

[0285] If the SN change occurred too early, and the SN change was initiated by the MN before the failure, the first node can perform appropriate self-optimization. The first node knows whether the SN change was initiated by the MN or the SN before the failure based on the saved UE context information. If the SN change was initiated by the SN before the failure, the first node sends a handover report message to the second node. The handover report can also be an SCG handover report or other messages, containing the message "SN change too early," and including the cell identifier of the PSCell of the SN where the SCG radio failure occurred and / or the PSCell cell identifier of the source SN.

[0286] The first node, based on the information received from the UE in step 601 or based on the saved UE context information, determines whether the UE has recently undergone a SN change. If, after a failure, the suitable SN cell for the UE to access is neither the source SN of the previous SN change, nor the SN cell where the failure occurred, nor the destination SN cell of the SN change, then the UE has been switched to an incorrect SN cell. The first node determines whether there has been a recent SN change based on the interval between the received information about the previous SN change and the SCG radio connection failure, or based on the time difference between the last transmission of UE context to the source SN and the failure indication. The first node received the source cell identifier of the previous SN change in step 601 or knows the source cell identifier of the previous SN change based on the saved UE context. The suitable cell for the UE to access after a failure can be sent by the UE to the first node, determined by the first node based on the UE's measurement report, or a cell on another SN that the first node decides to configure for the UE.

[0287] When switching to an incorrect SN cell, if the SN change was initiated by the MN before the failure occurred, the first node can perform appropriate self-optimization. The first node knows whether the SN change was initiated by the MN or the SN before the failure based on the saved UE context information. If the SN change was initiated by the SN before the failure, the first node sends a handover report message to the second node, i.e., the source SN. The handover report can also be an SCG handover report or other messages. The message includes the cell identifier of the PSCell of the SN where the SCG radio connection failure occurred, the PSCell cell identifier of the source SN, and / or the cell identifier of the cell on the SN suitable for UE access.

[0288] The node receiving the handover report can determine the type of SN change failure based on the received information and / or stored information such as a list of SNs to which the UE is connected, and optimize the parameters used to generate the SN change decision to reduce or avoid similar errors from recurring. The node receiving the handover report can be either the first node or the second node.

[0289] Figure 7 This is a flowchart illustrating a self-optimization method according to an example embodiment of the present disclosure. As shown, the first node can be MN, the third node can be the SN where the SCG radio connection fails after a long UE stays on the SN, or the source SN in the SN change process, and the second node can be the SN where the SCG radio connection fails after the SN change is completed, or the destination SN in the SN change process. Detailed descriptions of some steps that may obscure the subject matter of the invention are omitted here. The method includes the following steps:

[0290] Step 701: The first node configures the third node as the UE's SN.

[0291] During the process of configuring the third node as the UE's SN, the first node obtains the UE's PSCell information from the third node. The PSCell information includes the PSCell cell identifier, and / or PLMN identifier, and TAC, or TAI. The first node obtains the UE's PSCell information from the third node using two methods:

[0292] Method 1: In the secondary node addition request message, the first node can always request the third node to report the information of the PSCell selected by the third node. For example, the first node always includes a location information reporting element in the secondary base station in the SN addition request message. After receiving the SN addition request message, the third node reports the location information in the secondary base station according to the location information in the message. The SN addition request confirmation message includes the location information in the SN. The location information in the SN can be the Global Cell Identifier and / or TAC, or TAI. The first node can actively trigger the third node to report the location information in the SN.

[0293] Method 2: The third node includes the UE's location information in the SN in each SN addition request confirmation message. This location information can be a global cell identifier. That is, even if the first node does not request location information in the SN, the third node will still report the UE's location information in the SN.

[0294] The first node stores the received location information of the UE at the third node.

[0295] Using the above method, the MN can always know the UE's location information in the SN, which can be used for subsequent self-configuration and self-optimization processes.

[0296] The first node can add the information of the third node to the information list of the SN connected to the UE, as described above.

[0297] If there is a subsequent SN change, such as the SN changing from the third node to the second node, the first node can always know the UE's location information at the second node using the same method described above. This location information can be the PSCell information where the UE is located. The PSCell information includes the PSCell cell identifier, and / or PLMN identifier and TAC, or TAI. The first node stores the received UE location information at the second node.

[0298] The first node can add the information of the third node to the information list of the SNs connected to the UEs that have been served, with the most recent information placed at the top. The information of the UEs served includes the PSCell identifier, cell type, and the time the UE stayed in that cell, as described above.

[0299] Step 702: If the UE fails at the SN, the UE sends a secondary cell group (SCG) failure message to the first node.

[0300] The first node determines the cause of the failure using a method similar to that in step 602. Based on the received SCG failure report and step 701, the first node already knows the information of the SN that the UE was connected to when it failed, the information of the source SN that triggered the last handover, and the information of the SN cell suitable for the UE to access after the failure. Thus, the first node can detect the cause of the failure.

[0301] If it is detected that the UE has performed a handover too late, too early, or switched to the wrong SN cell at the third node, the first node sends a handover report to the third node. The content of the message and the behavior of the third node are similar to those described in step 602, and will not be repeated here.

[0302] The following process uses Example 3 as an example, in which the information needed to determine the type of SN change failure is obtained by maintaining the UE's context information through the network.

[0303] The first node sends a failure indication message to the second node. This failure indication message can also be a secondary cell group (SCG) failure indication or other messages, used to send SCG failure information to the second node. The second node can be the SN where the SCG radio connection failure occurred. The first node knows the SN where the SCG radio connection failure occurred based on information stored in the UE context.

[0304] The message contains a report of SCG failure received from the UE. The message also includes information on whether the previous SN change process was triggered by the MN or the SN.

[0305] The message may also contain one or more of the following information:

[0306] SCG failure message;

[0307] Information about the source SN from the last SN change, including the cell identifier of the PSCell, and optionally, the TAC and PLMN identifiers, or TAI, to which the cell belongs;

[0308] Information about the SN where the SCG wireless connection failed includes the cell identifier of the PSCell, and optionally, may also include the TAC and PLMN identifiers, or TAI, to which the cell belongs;

[0309] After the SCG radio connection fails, the cell identifier of a cell suitable for configuring the SN for the UE may optionally include the TAC and PLMN identifiers, or TAI, to which the cell belongs.

[0310] The interval between the last SN change process and the SCG wireless connection failure.

[0311] The identifier assigned to the UE by the SN when the SCG radio connection fails. This identifier can be the S-NG-RAN node UE XnAP ID in the Xn message or the SgNB UE X2AP ID in the X2 message, or it can be C-RNTI;

[0312] The identifier assigned to the UE by the MN. This identifier can be the M-NG-RAN node UE XnAP ID in the Xn message or the MeNB UE X2AP ID in the X2 message, or it can be a C-RNTI;

[0313] The types of SCG wireless connection failures can be SN change failure or radio link failure.

[0314] Information list of SNs to which the UE is connected, or UE history information containing information list of SNs to which the UE is connected;

[0315] Mobility Information.

[0316] The second node determines the cause of the failure, which may include changing the SN too early, changing the SN too late, or changing to the wrong SN cell.

[0317] Based on the received information, if the UE has been camped on the cell of the second node for a long time (without recent SN changes), and the UE has a suitable cell on another SN for access when the failure occurs, then the SN change was too late. The suitable cell on another SN for access can be one sent by the UE to the first node and then to the second node, or it can be determined by the second node based on the UE's measurement report, or it can be a cell on another SN that the first node decides to configure for the UE and then sends it to the second node. The second node knows whether there has been a recent SN change based on the interval between the last received SN change process and the SCG radio connection failure, or based on the time difference between the last received SN reconfiguration completion and failure indication.

[0318] If the SN change is too late, the second node can know that it or the MN should have triggered an SN change process, but neither did, leading to the UE's SN failure. Therefore, both the second and first nodes are the nodes causing the problem. The second node can perform appropriate self-optimization. The second node sends a handover report message to the first node. The handover report can also be an SCG handover report or other messages, containing the late SN change information and the cell identifier of the PSCell where the UE failed at the second node.

[0319] Based on the received information, if the UE has recently undergone a SN change, and the SN of the source cell of the SN change is a suitable SN for UE access after a failure, or if the source cell of the SN change is a suitable SN for UE access after a failure, then the SN change was too early. The second node determines whether there has been a recent SN change based on the interval between the last received SN change process and the SCG radio connection failure, or based on the time difference between the last received SN reconfiguration completion and failure indication. The second node receives the source cell identifier of the SN change from the first node. The suitable cell for UE access after a failure can be sent by the UE to the first node and then sent by the first node to the second node, or it can be determined by the second node based on the UE's measurement report, or it can be a cell on another SN that the first node decides to configure for the UE and then sends it to the second node.

[0320] If the SN change is too early, based on whether the most recent SN change was triggered by the MN or the SN received from the first node, for the previous SN change triggered by the MN, the second node sends a handover report message to the first node. The handover report can also be an SCG handover report or other messages, containing the message "SN change too early," and including the cell identifier of the PSCell where the UE failed at the second node. For the previous SN change triggered by the SN, the second node sends a handover report message to the third node, i.e., the source SN. The handover report can also be an SCG handover report or other messages, containing the message "SN change too early," and including the cell identifier of the PSCell where the UE failed at the second node and / or the PSCell cell identifier of the source SN.

[0321] Based on the received information, if the UE recently underwent a SN change, and the suitable SN cell for UE access after the failure is neither the source SN of the previous SN change nor the SN cell where the failure occurred or the destination SN cell of the SN change, then it has been changed to an incorrect SN cell. The second node determines whether there has been a recent SN change based on the interval between the received information about the previous SN change process and the SCG radio connection failure, or based on the time difference between the previously received SN reconfiguration completion and failure indication. The second node receives the source cell identifier of the SN change from the first node. The suitable cell for UE access after the failure can be sent by the UE to the first node and then by the first node to the second node, or it can be determined by the second node based on the UE's measurement report, or it can be a cell on another SN that the first node decides to configure for the UE and then sends it to the second node.

[0322] For a change to an incorrect SN cell, based on whether the most recent SN change received from the first node was triggered by the MN or the SN, the second node sends a handover report message to the first node for the previous SN change triggered by the MN. The handover report can also be an SCG handover report or other messages. These messages include the cell identifier of the PSCell where the UE failed at the second node, the PSCell cell identifier of the source SN, and / or the PSCell cell identifier on the SN suitable for UE access. For the previous SN change triggered by the SN, the second node sends a handover report message to the third node, i.e., the source SN. The handover report can also be an SCG handover report or other messages. These messages include the cell identifier of the PSCell where the UE failed at the second node, the PSCell cell identifier of the source SN, and / or the PSCell cell identifier on the SN suitable for UE access.

[0323] The message may also contain a combination of one or more of the following information:

[0324] SCG failure message;

[0325] The types of SN change failures can be SN change too late, SN change too early, or SN change to the wrong cell;

[0326] The identifier assigned to the UE by the SN when the SCG radio connection fails. This identifier can be the S-NG-RAN node UE XnAP ID in the Xn message or the SgNB UE X2AP ID in the X2 message, or it can be C-RNTI;

[0327] The identifier assigned to the UE by the MN. This identifier can be the M-NG-RAN node UE XnAP ID in the Xn message or the MeNB UE X2AP ID in the X2 message, or it can be a C-RNTI;

[0328] The types of SCG wireless connection failures can be SN change failure or radio link failure.

[0329] The cell identifier of the PSCell of the source SN that the SN changes may optionally include the TAC and PLMN identifiers, or TAI, to which the cell belongs;

[0330] The cell identifier of the PSCell of the SN where the SCG wireless connection failure occurred may optionally include the TAC and PLMN identifiers, or TAI, to which the cell belongs.

[0331] The cell identifier of a cell of an SN suitable for access after the SCG wireless connection fails. Optionally, it may also include the TAC and PLMN identifiers, or TAI, to which the cell belongs.

[0332] The interval between the last SN change process and the SCG wireless connection failure;

[0333] Information list of SNs to which the UE is connected, or UE history information containing information list of SNs to which the UE is connected;

[0334] Mobility Information.

[0335] The node receiving the handover report can determine the type of SN change failure based on the received information and / or stored information such as the list of SNs to which the UE is connected, and optimize the parameters used to generate the SN change decision to reduce or avoid similar errors from recurring. The node receiving the handover report can be either the first or third node.

[0336] Figure 8 This is a flowchart illustrating a self-optimization method according to an example embodiment of the present disclosure. For example... Figure 8 As shown, the first node can be MN, the second node can be the SN of the PSCell to which the UE is connected, the third node can be the SN of another PSCell to which the UE is connected, and the fourth node can be the SN of yet another PSCell to which the UE is connected. The second, third, and fourth nodes can all be the same, two of them can be the same, or they can all be different. Detailed descriptions of some steps that might obscure the subject matter of this invention are omitted here. The method includes the following steps:

[0337] Step 801: The first node configures the second node as the UE's SN. The first node or the second node initiates an SN change process to configure the third node as the UE's SN.

[0338] During the UE connection to the second node, the PSCell can be changed from one cell of the second node to another cell of the second node.

[0339] When the third node is configured as the UE's SN, the UE's PSCell changes from a cell of the second node to a cell of the third node.

[0340] The second node can use inter-node messages to send a list of PSCell information generated by the second node to the first node, showing the PSCell information that the UE has connected to. The list may include information about one or more PSCells that the UE has connected to. This information may include at least one of the following: the identifier of the SN to which the PSCell belongs, the duration of the UE's connection to the PSCell, the reason for the PSCell being changed, and the identifier of the associated MN. The identifier of the SN may include the PSCell ID, and optionally, may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs, and / or the node ID of the SN. The MN identifier may be a PCell ID, and optionally, may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs, and / or the node ID of the MN.

[0341] The message between the second node and the first node can be an Xn message or an X2 message. The Xn message can be an S-Node Modification Request Acknowledge, S-Node Modification Required, S-NodeChange Required, S-Node Release Request Acknowledge, S-Node Release Required, Access and Mobility Indication, or a newly defined XN message. The X2 message can be an SgNB Modification Request Acknowledge, SgNB Modification Required, SgNBChange Required, SgNB Release Request Acknowledge, SgNB Release Required, SeNB Modification Request Acknowledge, SeNB Modification Required, SeNBChange Required, SeNB Release Request Acknowledge, SeNB Release Required, Handover Report, RLF Indication, or a newly defined X2 message.

[0342] The first node can determine whether the PSCell change was initiated by the first node or the second node based on the signaling process that occurs when the PSCell is changed. The first node also saves the result of the determination.

[0343] Step 802: The first or third node initiates an SN change process to configure the fourth node as the UE's SN.

[0344] During the UE connection to the third node, the PSCell can be changed from one cell of the third node to another cell of the third node.

[0345] When the fourth node is configured as the UE's SN, the UE's PSCell changes from a cell of the third node to a cell of the fourth node.

[0346] During the UE connection to the fourth node, the PSCell can be changed from one cell of the fourth node to another cell of the fourth node.

[0347] The third node can use the message between the third node and the first node to send the list of PSCell information that the UE has connected to, generated by the third node, to the first node.

[0348] The fourth node can use the message between the fourth node and the first node to send the list of PSCell information that the UE has connected to, generated by the fourth node, to the first node.

[0349] The list may include information about one or more PSCells that the UE has connected to. The information may include at least one of the following: the identification information of the SN to which the PSCell belongs, the duration of the UE's connection to the PSCell, the reason for the PSCell being changed, and the identification information of the associated MN. The identification information of the SN may include the PSCell ID, and optionally, may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs, and / or the node ID of the SN. The MN identification information may be a PCell ID, and optionally, may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs, and / or the node ID of the MN.

[0350] The messages between the third node and the first node, and between the fourth node and the first node, can be either Xn messages or X2 messages. Refer to step 801 for details on the Xn or X2 messages.

[0351] The first node can determine whether the PSCell change was initiated by the first node or the third node based on the signaling process that occurs when the PSCell is changed. The first node also saves the result of the determination.

[0352] Step 803: The first node sends a message to the second node, indicating that an SN Change Ping-pong has occurred.

[0353] The first node determines that an SN ChangePing-pong has occurred based on the received list of PSCell information connected to by the UE. Simultaneously, the first node determines, based on its stored information, whether the SN change process from the second node to the third node was initiated by the first node or the second node.

[0354] If the decision is initiated by the second node, the first node will send the SN Change Ping-pong determination and / or the list of PSCell information received by the UE to the second node using a message exchanged between the second and first nodes. If the decision is initiated by the first node, the first node can optimize the parameters used to generate the SN Change decision to reduce or avoid similar errors from recurring.

[0355] The message between the second node and the first node can be an Xn message or an X2 message. The Xn message can be a Handover Report, an Access and Mobility Indication, or a newly defined Xn message. The X2 message can be a Handover Report, an RLF Indication, or a newly defined X2 message.

[0356] The second node can optimize the parameters used to generate the SN change decision based on the received information, in order to reduce or avoid similar errors from happening again.

[0357] Figure 9 This is a flowchart illustrating a self-optimization method according to an example embodiment of the present disclosure. For example... Figure 9 As shown, the first node can be MN1, the second node can be SN2, the third node can be MN2, the fourth node can be SN3, and the fifth node can be SN4. The second, fourth, and fifth nodes can all be the same, two of them can be the same, or they can all be different. Detailed descriptions of some steps that might obscure the subject matter of this invention are omitted here. The method includes the following steps:

[0358] Step 901: The first node configures the second node as the UE's SN, the first node initiates a handover process to the third node, during the handover process, the fourth node is configured as the UE's SN, and the second node is released.

[0359] The second node can use inter-node messages to send a list of PSCell information generated by the second node to the first node, showing the information of one or more PSCells that the UE has connected to. This list may include information about one or more PSCells that the UE has connected to. The information may include at least one of the following: the identifier of the SN to which the PSCell belongs, the duration of the UE's connection to the PSCell, the reason for the PSCell being changed, and the identifier of the associated MN. The identifier of the SN may include the PSCell ID, and optionally, may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs, and / or the node ID of the SN. The MN identifier may be a PCell ID, and optionally, may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs, and / or the node ID of the MN.

[0360] The message between the second node and the first node can be an Xn message or an X2 message. The Xn message can be an S-Node Modification Request Acknowledge, S-Node Modification Required, S-Node Change Required, S-Node Release Request Acknowledge, S-Node Release Required, or a newly defined Xn message. The X2 message can be an SgNB Modification Request Acknowledge, SgNB Modification Required, SgNB Change Required, SgNB Release Request Acknowledge, SgNB Release Required, SeNB Modification Request Acknowledge, SeNB Modification Required, SeNB Change Required, SeNB Release Request Acknowledge, SeNB Release Required, or a newly defined X2 message.

[0361] Step 902: The first node can use the inter-node message to send the list of PSCell information received by the first node, which contains information about the UE that has been connected to, to the third node. Alternatively, the first node can use Ng messages or S1 messages and forward them through the core network node to send the list of PSCell information received by the first node to the third node.

[0362] The message between the third node and the first node can be an Xn message or an X2 message. The Xn message can be an Access and Mobility Indication, a Handover Request, an SN Status Transfer, or a newly defined Xn message. The X2 message can be a Handover Request, an SN Status Transfer, or a newly defined X2 message.

[0363] The Ng message can be an Uplink RAN ​​Configuration Transfer, a Downlink RAN ​​Configuration Transfer, or a newly defined Ng message. The S1 message can be an eNB Configuration Transfer, an MME Configuration Transfer, an eNB Direct Information Transfer, an MME Direct Information Transfer, or a newly defined S1 message.

[0364] The first node may also send a list of PSCell information that the UE has connected to to the third node during the handover process described in step 901. For example, it may use an Xn message Handover Request or an X2 message Handover Request, which carries the list of PSCell information that the UE has connected to.

[0365] The first node can also send the list of PSCell information that the UE has connected to during the handover process described in step 901 to the third node using Ng messages or S1 messages and forwarded by the core network node. For example, it can use Ng messages Handover Required and Handover Request, or S1 messages Handover Required and Handover Request, and the Ng messages or S1 messages carry the list of PSCell information that the UE has connected to.

[0366] Step 903: The third or fourth node initiates the SN change process to configure the fifth node as the UE's SN.

[0367] The fourth node can use the message between the fourth node and the third node to send the list of PSCell information that the UE has connected to, generated by the fourth node, to the first node.

[0368] The message between the fourth node and the third node can be an Xn message or an X2 message. Refer to step 901 for details regarding the Xn message or X2 message.

[0369] The third node determines that an SN Change Ping-pong has occurred based on the received list of PSCell information that the UE has connected to. Since the process of configuring the fourth node as the UE's SN in step 901 is initiated by the third node, the third node can optimize the parameters used to generate the SN change decision based on the received information to reduce or avoid similar errors from happening again.

[0370] Figure 10 An embodiment according to this disclosure is illustrated schematically.

[0371] In this embodiment, whether to initiate the SN change process is determined by MN. MN, SN1, and SN2 are all gNB. Detailed descriptions of some steps that may obscure the subject matter of this invention are omitted here.

[0372] Step 1001: MN configures the UE's SN to SN1.

[0373] Step 1002: Due to a change in the radio signal quality of SN1, and the MN failing to initiate a timely SN change process from SN1 to another SN, the UE experiences an SCG radio connection failure on SN1. The UE sends an NR RRC message SCGFailureInformation to the MN. This message contains one or more of the following information:

[0374] SN information (i.e., SN1) indicating an SCG wireless connection failure;

[0375] Source SN information during the last SN change;

[0376] The cell identifier of a cell of an SN suitable for UE access after the UE reports an SCG failure. Optionally, it may also include the TAC and PLMN identifiers of the cell, or TAI;

[0377] The type of SCG wireless connection failure is radio link failure;

[0378] The identifier C-RNTI assigned to the UE by the SN when an SCG radio connection failure occurs;

[0379] The identifier C-RNTI assigned by the MN to the UE;

[0380] UE measurement report.

[0381] The SN information includes the Cell ID of the PSCell, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs.

[0382] Step 1003: MN can select SN2 as the SN suitable for UE access based on the cell of the SN suitable for access after the failure reported by the UE, and / or the measurement report of the UE.

[0383] If the SCGFailureInformation message only carries the SN information of the SCG radio connection failure, or if the source SN information during the last SN change is the same as the SN information of the SN that caused the SCG radio connection failure, and the suitable SN for access is different from the SN that caused the SCG radio connection failure, and the type of SCG radio connection failure is radio link failure, the MN can determine that the type of SN change failure is SN change too late.

[0384] Step 1004: The MN sends a first message to the SN (SN1) where the SCG wireless connection failed. The first message can be either the Xn message Failure Indication or the newly defined Xn message SCG Failure Indication.

[0385] The message contains one or more combinations of the following information:

[0386] The SCG failure information;

[0387] The type of failure when changing SN could be SN change too late;

[0388] A symbol indicating that this SN change process was determined by MN;

[0389] An identifier assigned to the UE by the SN when an SCG radio connection failure occurs. This identifier can be the S-NG-RAN node UE XnAP ID identified in the Xn message, or it can be the C-RNTI.

[0390] The identifier assigned to the UE by the MN. This identifier can be the M-NG-RAN node UE XnAP ID in the Xn message, or it can be the C-RNTI.

[0391] The type of SCG wireless connection failure could be radio link failure;

[0392] The source SN information that the SN changes;

[0393] SN information indicating an SCG wireless connection failure;

[0394] SN information suitable for access after wireless connection failure.

[0395] The SN information is the Cell ID of the PSCell, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs. The SN information suitable for access includes the Cell ID of the cell to which it belongs, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs.

[0396] If MN does not send the SN change failure type, or SN1 ignores the SN change failure type sent by MN, SN1 can determine the SN change failure type itself according to the method in step 1003 based on the received information.

[0397] Step 1005: The previous message indicated that the SN change process was determined by MN, therefore SN1 sends a second message to MN. The second message can be either the Xn message Handover Report or the newly defined Xn message SCG Change Report.

[0398] The message contains one or more combinations of the following information:

[0399] The SCG failure information;

[0400] The type of failure when changing SN could be SN change too late;

[0401] The identifier assigned to the UE by MN in the previous message.

[0402] The source SN information that the SN changes;

[0403] SN information indicating an SCG wireless connection failure;

[0404] SN information suitable for access after wireless connection failure;

[0405] The type of SCG wireless connection failure can be radio link failure.

[0406] The SN information is the Cell ID of the PSCell, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs. The SN information suitable for access includes the Cell ID of the cell to which it belongs, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs.

[0407] MN can optimize the parameters used to generate SN change decisions based on the type of SN change failure determined by SN1, or by determining the type of SN change failure on its own, thereby reducing or avoiding the recurrence of similar errors.

[0408] Figure 11 Embodiment 2 according to this disclosure is illustrated schematically.

[0409] In this embodiment, whether to initiate the SN change process is determined by MN. MN, SN1, SN2, and SN3 are all gNB. Detailed descriptions of some steps that may obscure the subject matter of this invention are omitted here.

[0410] Step 1101: MN configures the UE's SN to SN1.

[0411] Step 1102: MN initiates the SN change process from SN1 to SN2.

[0412] Step 1103: The UE experiences an SCG radio connection failure on SN2. The UE sends an NR RRC message SCGFailureInformation to the MN. This message contains one or more combinations of the following information:

[0413] SN information (i.e., SN2) indicating an SCG wireless connection failure;

[0414] The source SN information (i.e., SN1) during the last SN change process;

[0415] The cell identifier of a cell of an SN suitable for UE access after the UE reports an SCG failure. Optionally, it may also include the TAC and PLMN identifiers of the cell, or TAI;

[0416] The interval between the last SN change process and the SCG wireless connection failure;

[0417] The types of SCG wireless connection failures can be SN change failure or radio link failure.

[0418] The identifier C-RNTI assigned to the UE by the SN when an SCG radio connection failure occurs;

[0419] The identifier C-RNTI assigned by the MN to the UE;

[0420] UE measurement report.

[0421] The SN information includes the Cell ID of the PSCell, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs.

[0422] Step 1104: MN can select SN3 as the SN suitable for UE access based on the cell of the SN suitable for access after the failure reported by the UE, and / or the measurement report of the UE.

[0423] SN3 can be the same as SN1.

[0424] If the SCG radio connection failure type is SN change failure, or the interval between the last SN change process and the SCG radio connection failure is less than a preset threshold, and SN2 is different from SN1 and SN3, MN can determine that the SN change failure type is either SN change too early or change to the wrong SN cell. If SN1 and SN3 are the same, the SN change failure type is SN change too early; if SN1 and SN3 are different, the SN change failure type is change to the wrong SN cell.

[0425] Step 1105: MN sends a first message to SN2, the SN where the SCG wireless connection failed. The first message can be either the Xn message Failure Indication or the newly defined Xn message SCG Failure Indication.

[0426] The message contains one or more combinations of the following information:

[0427] The SCG failure information;

[0428] The types of SN change failures can be either SN change too early or SN change to the wrong cell;

[0429] A symbol indicating that this SN change process was determined by MN;

[0430] An identifier assigned to the UE by the SN when an SCG radio connection failure occurs. This identifier can be the S-NG-RAN node UE XnAP ID identified in the Xn message, or it can be the C-RNTI.

[0431] The identifier assigned to the UE by the MN. This identifier can be the M-NG-RAN node UE XnAP ID in the Xn message, or it can be the C-RNTI.

[0432] The types of SCG wireless connection failures can be SN change failure or radio link failure.

[0433] The source SN information that the SN changes;

[0434] SN information indicating an SCG wireless connection failure;

[0435] SN information suitable for access after wireless connection failure;

[0436] The interval between the last SN change process and the SCG wireless connection failure.

[0437] The SN information is the Cell ID of the PSCell, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs. The SN information suitable for access includes the Cell ID of the cell to which it belongs, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs.

[0438] If MN does not send the SN change failure type, or SN1 ignores the SN change failure type sent by MN, SN1 can determine the SN change failure type itself according to the method in step 1104 based on the received information.

[0439] Step 1106: The previous message indicated that the SN change process was determined by MN, therefore SN2 sends a second message to MN. The second message can be either the Xn message Handover Report or the newly defined Xn message SCG Change Report.

[0440] The message contains one or more combinations of the following information:

[0441] The SCG failure information;

[0442] The types of SN change failures can be either SN change too early or SN change to the wrong cell;

[0443] The identifier assigned to the UE by MN in the previous message.

[0444] The source SN information that the SN changes;

[0445] SN information indicating an SCG wireless connection failure;

[0446] SN information suitable for access after wireless connection failure;

[0447] The types of SCG wireless connection failures can be SN change failure or radio link failure.

[0448] The interval between the last SN change process and the SCG wireless connection failure.

[0449] The SN information is the Cell ID of the PSCell, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs. The SN information suitable for access includes the Cell ID of the cell to which it belongs, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs.

[0450] MN can optimize the parameters used to generate SN change decisions based on the type of SN change failure determined by SN1, or by determining the type of SN change failure on its own, thereby reducing or avoiding the recurrence of similar errors.

[0451] Figure 12 Embodiment 3 according to this disclosure is illustrated schematically.

[0452] In this embodiment, whether to initiate the SN change process is determined by MN. MN is an eNB, and both SN1 and SN2 are en-gNBs. Detailed descriptions of some steps that may obscure the subject matter of this invention are omitted here.

[0453] Step 1201: MN configures the UE's SN to SN1.

[0454] Step 1202: Due to a change in the radio signal quality of SN1, and the MN failing to initiate a timely SN change process from SN1 to another SN, the UE experiences an SCG radio connection failure on SN1. The UE sends an EUTRAN RRC message SCGFailureInformationNR to the MN. This message contains one or more combinations of the following information:

[0455] SN information (i.e., SN1) indicating an SCG wireless connection failure;

[0456] Source SN information during the last SN change;

[0457] The cell identifier of a cell of an SN suitable for UE access after the UE reports an SCG failure. Optionally, it may also include the TAC and PLMN identifiers of the cell, or TAI;

[0458] The type of SCG wireless connection failure is radio link failure;

[0459] The identifier C-RNTI assigned to the UE by the SN when an SCG radio connection failure occurs;

[0460] The identifier C-RNTI assigned by the MN to the UE;

[0461] UE measurement report.

[0462] The SN information includes the Cell ID of the PSCell, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs.

[0463] Step 1203: MN can select SN2 as the SN suitable for UE access based on the cell of the SN suitable for access after the failure reported by the UE, and / or the measurement report of the UE.

[0464] If the SCGFailureInformationNR message only carries the SN information of the SCG radio connection failure, or if the source SN information during the last SN change is the same as the SN information of the SN that caused the SCG radio connection failure, and the suitable SN for access is different from the SN that caused the SCG radio connection failure, and the type of SCG radio connection failure is radio link failure, the MN can determine that the type of SN change failure is SN change too late.

[0465] Step 1204: The MN sends a first message to the SN (SN1) where the SCG wireless connection failed. The first message can be either the X2 message RLF Indication or the newly defined X2 message SCG Failure Indication.

[0466] The message contains one or more combinations of the following information:

[0467] The SCG failure information;

[0468] The type of failure when changing SN could be SN change too late;

[0469] A symbol indicating that this SN change process was determined by MN;

[0470] The identifier assigned to the UE by the SN when the SCG radio connection fails. This identifier can be the SgNBUE X2AP ID identified in the X2 message, or it can be the C-RNTI.

[0471] The identifier assigned to the UE by the MN. This identifier can be the MeNB UE X2AP ID identified in the X2 message, or it can be the C-RNTI;

[0472] The type of SCG wireless connection failure could be radio link failure;

[0473] The source SN information that the SN changes;

[0474] SN information indicating an SCG wireless connection failure;

[0475] SN information suitable for access after wireless connection failure.

[0476] The SN information is the Cell ID of the PSCell, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs. The SN information suitable for access includes the Cell ID of the cell to which it belongs, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs.

[0477] If MN does not send the SN change failure type, or SN1 ignores the SN change failure type sent by MN, SN1 can determine the SN change failure type itself according to the method in step 1203 based on the received information.

[0478] Step 1205: The previous message indicated that the SN change process was determined by the MN, therefore SN1 sends a second message to the MN. The second message can be either the X2 message Handover Report or the newly defined X2 message SCG Change Report.

[0479] The message contains one or more combinations of the following information:

[0480] The SCG failure information;

[0481] The type of failure when changing SN could be SN change too late;

[0482] The identifier assigned to the UE by MN in the previous message.

[0483] The source SN information that the SN changes;

[0484] SN information indicating an SCG wireless connection failure;

[0485] SN information suitable for access after wireless connection failure;

[0486] The type of SCG wireless connection failure can be radio link failure.

[0487] The SN information is the Cell ID of the PSCell, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs. The SN information suitable for access includes the Cell ID of the cell to which it belongs, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs.

[0488] MN can optimize the parameters used to generate SN change decisions based on the type of SN change failure determined by SN1, or by determining the type of SN change failure on its own, thereby reducing or avoiding the recurrence of similar errors.

[0489] Figure 13 Embodiment four according to this disclosure is illustrated schematically.

[0490] In this embodiment, whether to initiate the SN change process is determined by MN. MN is an eNB, and SN1, SN2, and SN3 are all en-gNBs. Detailed descriptions of some steps that may obscure the subject matter of this invention are omitted here.

[0491] Step 1301: MN configures the UE's SN to SN1.

[0492] Step 1302: MN initiates the SN change process from SN1 to SN2.

[0493] Step 1303: The UE experiences an SCG radio connection failure on SN2. The UE sends an EUTRAN RRC message SCGFailureInformationNR to the MN. This message contains one or more combinations of the following information:

[0494] SN information (i.e., SN2) indicating an SCG wireless connection failure;

[0495] The source SN information (i.e., SN1) during the last SN change process;

[0496] The cell identifier of a cell of an SN suitable for UE access after the UE reports an SCG failure. Optionally, it may also include the TAC and PLMN identifiers of the cell, or TAI;

[0497] The interval between the last SN change process and the SCG wireless connection failure;

[0498] The types of SCG wireless connection failures can be SN change failure or radio link failure.

[0499] The identifier C-RNTI assigned to the UE by the SN when an SCG radio connection failure occurs;

[0500] The identifier C-RNTI assigned by the MN to the UE;

[0501] UE measurement report.

[0502] The SN information includes the Cell ID of the PSCell, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs.

[0503] Step 1304: MN can select SN3 as the SN suitable for UE access based on the cell of the SN suitable for access after the failure reported by the UE, and / or the measurement report of the UE.

[0504] SN3 can be the same as SN1.

[0505] If the SCG radio connection failure type is SN change failure, or the interval between the last SN change process and the SCG radio connection failure is less than a preset threshold, and SN2 is different from SN1 and SN3, MN can determine that the SN change failure type is either SN change too early or change to the wrong SN cell. If SN1 and SN3 are the same, the SN change failure type is SN change too early; if SN1 and SN3 are different, the SN change failure type is change to the wrong SN cell.

[0506] Step 1305: The MN sends a first message to the SN (SN1) where the SCG wireless connection failed. The first message can be either the X2 message RLF Indication or the newly defined X2 message SCG Failure Indication.

[0507] The message contains one or more combinations of the following information:

[0508] The SCG failure information;

[0509] The types of SN change failures can be either SN change too early or SN change to the wrong cell;

[0510] A symbol indicating that this SN change process was determined by MN;

[0511] The identifier assigned to the UE by the SN when the SCG radio connection fails. This identifier can be the SgNBUE X2AP ID identified in the X2 message, or it can be the C-RNTI.

[0512] The identifier assigned to the UE by the MN. This identifier can be the MeNB UE X2AP ID identified in the X2 message, or it can be the C-RNTI.

[0513] The types of SCG wireless connection failures can be SN change failure or radio link failure.

[0514] The source SN information that the SN changes;

[0515] SN information indicating an SCG wireless connection failure;

[0516] SN information suitable for access after wireless connection failure;

[0517] The interval between the last SN change process and the SCG wireless connection failure.

[0518] The SN information is the Cell ID of the PSCell, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs. The SN information suitable for access includes the Cell ID of the cell to which it belongs, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs.

[0519] If MN does not send the SN change failure type, or SN1 ignores the SN change failure type sent by MN, SN1 can determine the SN change failure type itself according to the method in step 1203 based on the received information.

[0520] Step 1306: The previous message indicated that the SN change process was determined by the MN, therefore SN1 sends a second message to the MN. The second message can be either the X2 message Handover Report or the newly defined X2 message SCG Change Report.

[0521] The message contains one or more combinations of the following information:

[0522] The SCG failure information;

[0523] The type of SN change failure can be either SN change failure or radio link failure.

[0524] The identifier assigned to the UE by MN in the previous message.

[0525] The source SN information that the SN changes;

[0526] SN information indicating an SCG wireless connection failure;

[0527] SN information suitable for access after wireless connection failure;

[0528] The types of SCG wireless connection failures can be SN change failure or radio link failure.

[0529] The interval between the last SN change process and the SCG wireless connection failure.

[0530] The SN information is the Cell ID of the PSCell, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs. The SN information suitable for access includes the Cell ID of the cell to which it belongs, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs.

[0531] MN can optimize the parameters used to generate SN change decisions based on the type of SN change failure determined by SN1, or by determining the type of SN change failure on its own, thereby reducing or avoiding the recurrence of similar errors.

[0532] Figure 14 Embodiment five according to this disclosure is illustrated schematically.

[0533] In this embodiment, whether to initiate the SN change process is determined by MN. MN, SN1, and SN2 are all gNB. Detailed descriptions of some steps that may obscure the subject matter of this invention are omitted here.

[0534] Step 1401: The MN configures the UE's SN to SN1. During the SN addition process of Xn, SN1 reports the PSCell ID and its PLMN to the MN. The MN can determine the TrackingArea Code of the cell based on the information exchanged between the MN and SN1 during the Xn Setup process.

[0535] The MN adds the information of SN1 to the list of SNs connected to the UE in the UE History Information stored by the MN. This list may include information about one or more SNs connected to the UE. The information about the SNs connected to the UE may include the SN's identifier, and / or the duration of the UE's connection to that SN, and / or the reason the UE's SN is configured as that SN, and / or the associated MN identifier. The SN's identifier may include the PSCell ID, and optionally, may also include the TAC and PLMN identifiers, or TAI, and / or the node ID to which the cell belongs. The MN's identifier may be the PCell ID, and / or the MN node ID. Optionally, the MN may save this list as a separate information section instead of adding it to the UE History Information.

[0536] Step 1402: Due to a change in the radio signal quality of SN1, and the MN failing to initiate the SN change process from SN1 to another SN in a timely manner, the UE experiences an SCG radio connection failure on SN1. The UE sends an NR RRC message SCGFailureInformation to the MN, which includes the UE's measurement report.

[0537] Step 1403: The MN can select SN2 as the suitable SN for the UE to access based on the UE's measurement report. As described in step 1401, the MN adds the information of SN2 to the list of SNs connected to by the UE stored in the MN. Therefore, the MN can know the suitable SN information for access.

[0538] The MN learns from the SCGFailureInformation that an SCG radio connection failure occurred on the previous SN configured for the UE. It can also obtain information about the SN (SN1), its PSCell Cell ID, and the TAC and PLMN identifiers (or TAI) of that cell from the saved list of SNs connected to the UE. Therefore, the MN can determine the SN information where the SCG radio connection failure occurred, and this SN information should also be the source SN information from which the SN change occurred. Furthermore, the suitable SN for access is different from the SN where the SCG radio connection failure occurred.

[0539] Furthermore, since the MN did not initiate the SN change process, nor did it receive the signaling for the SN change process initiated by the SN, the MN can determine that the type of SCG wireless connection failure is radio link failure.

[0540] Based on the above information, MN can determine that the type of SN change failure is that SN was changed too late.

[0541] Step 1404: The MN sends a first message to the SN (SN1) where the SCG wireless connection failed. The first message can be either the Xn message Failure Indication or the newly defined Xn message SCG Failure Indication.

[0542] The message contains one or more combinations of the following information:

[0543] The SCG failure information;

[0544] The type of failure when changing SN could be SN change too late;

[0545] A symbol indicating that this SN change process was determined by MN;

[0546] An identifier assigned to the UE by the SN when an SCG radio connection failure occurs. This identifier may be the S-NG-RAN node UE XnAP ID identified in the Xn message.

[0547] The identifier assigned to the UE by the MN. This identifier can be the M-NG-RAN node UE XnAP ID in the Xn message, or it can be the C-RNTI.

[0548] The type of SCG wireless connection failure could be radio link failure;

[0549] The source SN information that the SN changes;

[0550] SN information indicating an SCG wireless connection failure;

[0551] SN information suitable for access after wireless connection failure;

[0552] Information list of SNs to which the UE is connected, or UE history information containing information list of SNs to which the UE is connected.

[0553] The SN information is the Cell ID of the PSCell, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs. The SN information suitable for access includes the Cell ID of the cell to which it belongs, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs.

[0554] SN1 can also determine the source SN information of the SN change, and / or the SN information of the SCG radio connection failure, and / or the SN information suitable for access after the radio connection failure, based on the information list of the SNs connected to the UE.

[0555] If MN does not send the SN change failure type, or SN1 ignores the SN change failure type sent by MN, SN1 can determine the SN change failure type itself according to the method in step 1403 based on the received information.

[0556] SN1 can confirm that the MN is the same as the MN currently associated with SN1 based on the MN identifier information associated with SN1 in the information list of the SN to which the UE is connected, thus avoiding erroneous operation.

[0557] Step 1405: The previous message indicated that the SN change process was determined by MN, therefore SN1 sends a second message to MN. The second message can be either the Xn message Handover Report or the newly defined Xn message SCG Change Report.

[0558] The message contains one or more combinations of the following information:

[0559] The SCG failure information;

[0560] The type of failure when changing SN could be SN change too late;

[0561] The identifier assigned to the UE by MN in the previous message.

[0562] The source SN information that the SN changes;

[0563] SN information indicating an SCG wireless connection failure;

[0564] SN information suitable for access after wireless connection failure;

[0565] The type of SCG wireless connection failure could be radio link failure;

[0566] Information list of SNs to which the UE is connected, or UE history information containing information list of SNs to which the UE is connected.

[0567] The SN information is the Cell ID of the PSCell, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs. The SN information suitable for access includes the Cell ID of the cell to which it belongs, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs.

[0568] MN can optimize the parameters used to generate SN change decisions based on the type of SN change failure determined by SN1, or by determining the type of SN change failure on its own, thereby reducing or avoiding the recurrence of similar errors.

[0569] Figure 15 Embodiment six according to this disclosure is illustrated schematically.

[0570] In this embodiment, whether to initiate the SN change process is determined by MN. MN, SN1, SN2, and SN3 are all gNB. Detailed descriptions of some steps that may obscure the subject matter of this invention are omitted here.

[0571] Step 1501: The MN configures the UE's SN to SN1. During the SN addition process of Xn, SN1 reports the PSCell ID and its PLMN to the MN. The MN can determine the TrackingArea Code of the cell based on the information exchanged between the MN and SN1 during the Xn Setup process.

[0572] The MN adds the information of SN1 to the list of SNs connected to the UE in the UE History Information stored by the MN. This list may include information about one or more SNs connected to the UE. The information about the SNs connected to the UE may include the SN's identifier, and / or the duration of the UE's connection to that SN, and / or the reason the UE's SN is configured as that SN, and / or the associated MN identifier. The SN's identifier may include the PSCell ID, and optionally, may also include the TAC and PLMN identifiers, or TAI, and / or the node ID to which the cell belongs. The MN's identifier may be the PCell ID, and / or the MN node ID. Optionally, the MN may save this list as a separate information section instead of adding it to the UE History Information.

[0573] Step 1502: The MN initiates the SN change process from SN1 to SN2. As described in step 1501, the MN adds the SN2 information to the list of SNs to which the UE is connected, which is stored in the MN.

[0574] Step 1503: The UE experiences an SCG radio connection failure on SN2. The UE sends an NR RRC message SCGFailureInformation to the MN. This message includes the UE's measurement report.

[0575] Step 1504: The MN can select SN3 as the suitable SN for the UE to access based on the UE's measurement report. As described in step 1401, the MN adds the information of SN3 to the list of SNs connected to by the UE stored in the MN. Therefore, the MN can know the suitable SN information for access.

[0576] SN3 can be the same as SN1.

[0577] The MN learns from the SCGFailureInformation that an SCG radio connection failure occurred on the previous SN configured for the UE. It can also obtain information about the SN (SN2), its PSCell Cell ID, and the TAC and PLMN identifiers (or TAI) of that cell from the saved list of SNs connected to the UE. Therefore, the MN can determine the SN information where the SCG radio connection failure occurred. Furthermore, the MN initiates an SN change process; therefore, the SN configured for the UE before SN2 is the source SN for the SN change. The MN can obtain information about the SN (SN1), its PSCell Cell ID, and the TAC and PLMN identifiers (or TAI) of that cell from the saved list of SNs connected to the UE. Therefore, the MN can determine the source SN information for the SN change.

[0578] If the SN change process is not completed successfully, the MN will receive an SCG failure message reported by the UE. The MN can determine that the type of SCG radio connection failure is SN change failure; otherwise, the type of SCG radio connection failure is radiolink failure.

[0579] The MN can also calculate the interval between the last SN change process and the SCG radio connection failure based on the time of the last SN change process and the SCG failure information received from the UE.

[0580] If the SCG radio connection failure type is SN change failure, or the interval between the last SN change process and the SCG radio connection failure is less than a preset threshold, and SN2 is different from SN1 and SN3, MN can determine that the SN change failure type is either SN change too early or change to the wrong SN cell. If SN1 and SN3 are the same, the SN change failure type is SN change too early; if SN1 and SN3 are different, the SN change failure type is change to the wrong SN cell.

[0581] Step 1505: The MN sends a first message to the SN (SN1) where the SCG wireless connection failed. The first message can be either the Xn message Failure Indication or the newly defined Xn message SCG Failure Indication.

[0582] The message contains one or more combinations of the following information:

[0583] The SCG failure information;

[0584] The types of SN change failures can be either SN change too early or SN change to the wrong cell;

[0585] A symbol indicating that this SN change process was determined by MN;

[0586] An identifier assigned to the UE by the SN when an SCG radio connection failure occurs. This identifier may be the S-NG-RAN node UE XnAP ID identified in the Xn message.

[0587] The identifier assigned to the UE by the MN. This identifier can be the M-NG-RAN node UE XnAP ID in the Xn message, or it can be the C-RNTI.

[0588] The types of SCG wireless connection failures can be SN change failure or radio link failure.

[0589] The source SN information that the SN changes;

[0590] SN information indicating an SCG wireless connection failure;

[0591] SN information suitable for access after wireless connection failure;

[0592] The interval between the last SN change process and the SCG wireless connection failure;

[0593] Information list of SNs to which the UE is connected, or UE history information containing information list of SNs to which the UE is connected.

[0594] The SN information is the Cell ID of the PSCell, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs. The SN information suitable for access includes the Cell ID of the cell to which it belongs, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs.

[0595] If MN does not send the SN change failure type, or SN1 ignores the SN change failure type sent by MN, SN1 can determine the SN change failure type itself according to the method in step 1504 based on the received information.

[0596] Step 1506: The previous message indicated that the SN change process was determined by MN, therefore SN1 sends a second message to MN. The second message can be either the Xn message Handover Report or the newly defined Xn message SCG Change Report.

[0597] The message contains one or more combinations of the following information:

[0598] The SCG failure information;

[0599] The types of SN change failures can be either SN change too early or SN change to the wrong cell;

[0600] The identifier assigned to the UE by MN in the previous message.

[0601] The source SN information that the SN changes;

[0602] SN information indicating an SCG wireless connection failure;

[0603] SN information suitable for access after wireless connection failure;

[0604] The types of SCG wireless connection failures can be SN change failure or radio link failure.

[0605] The interval between the last SN change process and the SCG wireless connection failure;

[0606] Information list of SNs to which the UE is connected, or UE history information containing information list of SNs to which the UE is connected.

[0607] The SN information is the Cell ID of the PSCell, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs. The SN information suitable for access includes the Cell ID of the cell to which it belongs, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs.

[0608] MN can optimize the parameters used to generate SN change decisions based on the type of SN change failure determined by SN1, or by determining the type of SN change failure on its own, thereby reducing or avoiding the recurrence of similar errors.

[0609] Figure 16 Embodiment seven according to this disclosure is illustrated schematically.

[0610] In this embodiment, whether to initiate the SN change process is determined by MN. MN is an eNB, and both SN1 and SN2 are en-gNBs. Detailed descriptions of some steps that may obscure the subject matter of this invention are omitted here.

[0611] Step 1601: The MN configures the UE's SN to SN1. During the SN addition process of X2, SN1 reports the PSCell ID to the MN, and the MN knows the PLMN used by the SCG. The MN can determine the Tracking Area Code of the cell based on the information exchanged between the MN and SN1 during the EN-DC Setup process.

[0612] The MN adds the information of SN1 to the list of SNs connected to the UE in the UE History Information stored by the MN. This list may include information about one or more SNs connected to the UE. The information about the SNs connected to the UE may include the SN's identifier, and / or the duration of the UE's connection to that SN, and / or the reason the UE's SN is configured as that SN, and / or the associated MN identifier. The SN's identifier may include the PSCell ID, and optionally, may also include the TAC and PLMN identifiers, or TAI, and / or the node ID to which the cell belongs. The MN's identifier may be the PCell ID, and / or the MN node ID. Optionally, the MN may save this list as a separate information section instead of adding it to the UE History Information.

[0613] Step 1602: Due to a change in the radio signal quality of SN1, and the MN failing to initiate the SN change process from SN1 to another SN in a timely manner, the UE experiences an SCG radio connection failure on SN1. The UE sends an EUTRAN RRC message SCGFailureInformationNR to the MN. This message includes the UE's measurement report.

[0614] Step 1603: The MN can select SN2 as the suitable SN for the UE to access based on the UE's measurement report. As described in step 1601, the MN adds the information of SN2 to the list of SNs connected to by the UE stored in the MN. Therefore, the MN can know the suitable SN information for access.

[0615] The MN learns from the SCGFailureInformationNR that an SCG radio connection failure occurred on the previous SN configured for the UE. It can also obtain information about the SN (SN1), its PSCell Cell ID, and the TAC and PLMN identifiers (or TAI) of that cell from the saved list of SNs connected to the UE. Therefore, the MN can determine the SN information where the SCG radio connection failure occurred, and this SN information should also be the source SN information from which the SN change occurred. Furthermore, the suitable SN for access is different from the SN where the SCG radio connection failure occurred.

[0616] Furthermore, since the MN did not initiate the SN change process, nor did it receive the signaling for the SN change process initiated by the SN, the MN can determine that the type of SCG wireless connection failure is radio link failure.

[0617] Based on the above information, MN can determine that the type of SN change failure is that SN was changed too late.

[0618] Step 1604: The MN sends a first message to the SN (SN1) where the SCG wireless connection failed. The first message can be either the X2 message RLF Indication or the newly defined X2 message SCG Failure Indication.

[0619] The message contains one or more combinations of the following information:

[0620] The SCG failure information;

[0621] The type of failure when changing SN could be SN change too late;

[0622] A symbol indicating that this SN change process was determined by MN;

[0623] The identifier assigned to the UE by the SN when the SCG radio connection fails. This identifier may be the SgNBUE X2AP ID identified in the X2 message;

[0624] The identifier assigned to the UE by the MN. This identifier can be the MeNB UE X2AP ID identified in the X2 message, or it can be the C-RNTI.

[0625] The type of SCG wireless connection failure could be radio link failure;

[0626] The source SN information that the SN changes;

[0627] SN information indicating an SCG wireless connection failure;

[0628] SN information suitable for access after wireless connection failure;

[0629] Information list of SNs to which the UE is connected, or UE history information containing information list of SNs to which the UE is connected.

[0630] The SN information is the Cell ID of the PSCell, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs. The SN information suitable for access includes the Cell ID of the cell to which it belongs, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs.

[0631] SN1 can also determine the source SN information of the SN change, and / or the SN information of the SCG radio connection failure, and / or the SN information suitable for access after the radio connection failure, based on the information list of the SNs connected to the UE.

[0632] If MN does not send the SN change failure type, or SN1 ignores the SN change failure type sent by MN, SN1 can determine the SN change failure type itself according to the method in step 1603 based on the received information.

[0633] Step 1605: The previous message indicated that the SN change process was determined by the MN, therefore SN1 sends a second message to the MN. The second message can be either the X2 message Handover Report or the newly defined X2 message SCG Change Report.

[0634] The message contains one or more combinations of the following information:

[0635] The SCG failure information;

[0636] The type of failure when changing SN could be SN change too late;

[0637] The identifier assigned to the UE by MN in the previous message.

[0638] The source SN information that the SN changes;

[0639] SN information indicating an SCG wireless connection failure;

[0640] SN information suitable for access after wireless connection failure;

[0641] The type of SCG wireless connection failure could be radio link failure;

[0642] Information list of SNs to which the UE is connected, or UE history information containing information list of SNs to which the UE is connected.

[0643] The SN information is the Cell ID of the PSCell, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs. The SN information suitable for access includes the Cell ID of the cell to which it belongs, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs.

[0644] MN can optimize the parameters used to generate SN change decisions based on the type of SN change failure determined by SN1, or by determining the type of SN change failure on its own, thereby reducing or avoiding the recurrence of similar errors.

[0645] Figure 17 Embodiment 8 according to this disclosure is illustrated schematically.

[0646] In this embodiment, whether to initiate the SN change process is determined by MN. MN is an eNB, and SN1, SN2, and SN3 are all en-gNBs. Detailed descriptions of some steps that may obscure the subject matter of this invention are omitted here.

[0647] Step 1701: The MN configures the UE's SN to SN1. During the SN addition process of X2, SN1 reports the PSCell ID to the MN, and the MN knows the PLMN used by the SCG. The MN can determine the Tracking Area Code of the cell based on the information exchanged between the MN and SN1 during the EN-DC Setup process.

[0648] The MN adds the information of SN1 to the list of SNs connected to the UE in the UE History Information stored by the MN. This list may include information about one or more SNs connected to the UE. The information about the SNs connected to the UE may include the SN's identifier, and / or the duration of the UE's connection to that SN, and / or the reason the UE's SN is configured as that SN, and / or the associated MN identifier. The SN's identifier may include the PSCell ID, and optionally, may also include the TAC and PLMN identifiers, or TAI, and / or the node ID to which the cell belongs. The MN's identifier may be the PCell ID, and / or the MN node ID. Optionally, the MN may save this list as a separate information section instead of adding it to the UE History Information.

[0649] Step 1702: The MN initiates the SN change process from SN1 to SN2. As described in step 1701, the MN adds the SN2 information to the list of SNs to which the UE is connected, which is stored in the MN.

[0650] Step 1703: The UE experiences an SCG radio connection failure on SN2. The UE sends an EUTRN RRC message SCGFailureInformationNR to the MN. This message includes the UE's measurement report.

[0651] Step 1704: The MN can select SN3 as the suitable SN for the UE to access based on the UE's measurement report. As described in step 1701, the MN adds the information of SN3 to the list of SNs connected to by the UE stored in the MN. Therefore, the MN can know the suitable SN information for access.

[0652] SN3 can be the same as SN1.

[0653] The MN learns from the SCGFailureInformationNR that an SCG radio connection failure occurred on the previous SN configured for the UE. It can also obtain information about the SN (SN2), its PSCell Cell ID, and the TAC and PLMN identifiers (or TAI) of that cell from the saved list of SNs connected to the UE. Therefore, the MN can determine the SN information where the SCG radio connection failure occurred. Furthermore, the MN initiates an SN change process; therefore, the SN previously configured for the UE (SN2) is the source SN for the change. The MN can obtain information about the SN (SN1), its PSCell Cell ID, and the TAC and PLMN identifiers (or TAI) of that cell from the saved list of SNs connected to the UE. Therefore, the MN can determine the source SN information for the change.

[0654] If the SN change process is not completed successfully, the MN will receive an SCG failure message reported by the UE. The MN can determine that the type of SCG radio connection failure is SN change failure; otherwise, the type of SCG radio connection failure is radiolink failure.

[0655] The MN can also calculate the interval between the last SN change process and the SCG radio connection failure based on the time of the last SN change process and the SCG failure information received from the UE.

[0656] If the SCG radio connection failure type is SN change failure, or the interval between the last SN change process and the SCG radio connection failure is less than a preset threshold, and SN2 is different from SN1 and SN3, MN can determine that the SN change failure type is either SN change too early or change to the wrong SN cell. If SN1 and SN3 are the same, the SN change failure type is SN change too early; if SN1 and SN3 are different, the SN change failure type is change to the wrong SN cell.

[0657] Step 1705: The MN sends a first message to the SN (SN1) where the SCG wireless connection failed. The first message can be either the X2 message RLF Indication or the newly defined X2 message SCG Failure Indication.

[0658] The message contains one or more combinations of the following information:

[0659] The SCG failure information;

[0660] The types of SN change failures can be either SN change too early or SN change to the wrong cell;

[0661] A symbol indicating that this SN change process was determined by MN;

[0662] The identifier assigned to the UE by the SN when the SCG radio connection fails. This identifier may be the SgNBX2AP ID identified in the X2 message;

[0663] The identifier assigned to the UE by the MN. This identifier can be the MeNB UE X2AP ID identified in the X2 message, or it can be the C-RNTI;

[0664] The types of SCG wireless connection failures can be SN change failure or radio link failure.

[0665] The source SN information that the SN changes;

[0666] SN information indicating an SCG wireless connection failure;

[0667] SN information suitable for access after wireless connection failure;

[0668] The interval between the last SN change process and the SCG wireless connection failure.

[0669] The SN information is the Cell ID of the PSCell, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs. The SN information suitable for access includes the Cell ID of the cell to which it belongs, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs.

[0670] If MN does not send the SN change failure type, or SN1 ignores the SN change failure type sent by MN, SN1 can determine the SN change failure type itself according to the method in step 1704 based on the received information.

[0671] Step 1706: The previous message indicated that the SN change process was determined by MN, therefore SN1 sends a second message to MN. The second message can be either the X2 message Handover Report or the newly defined X2 message SCG Change Report.

[0672] The message contains one or more combinations of the following information:

[0673] The SCG failure information;

[0674] The types of SN change failures can be either SN change too early or SN change to the wrong cell;

[0675] The identifier assigned to the UE by MN in the previous message.

[0676] The source SN information that the SN changes;

[0677] SN information indicating an SCG wireless connection failure;

[0678] SN information suitable for access after wireless connection failure;

[0679] The types of SCG wireless connection failures can be SN change failure or radio link failure.

[0680] The interval between the last SN change process and the SCG wireless connection failure;

[0681] Information list of SNs to which the UE is connected, or UE history information containing information list of SNs to which the UE is connected.

[0682] The SN information is the Cell ID of the PSCell, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs. The SN information suitable for access includes the Cell ID of the cell to which it belongs, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs.

[0683] MN can optimize the parameters used to generate SN change decisions based on the type of SN change failure determined by SN1, or by determining the type of SN change failure on its own, thereby reducing or avoiding the recurrence of similar errors.

[0684] Figure 18 Embodiment nine according to this disclosure is illustrated schematically.

[0685] In this embodiment, whether to initiate the SN change process is determined by the SN. MN, SN1, and SN2 are all gNB. Detailed descriptions of some steps that may obscure the subject matter of this invention are omitted here.

[0686] Step 1801: MN sends an S-NODE Addition Request message to SN1.

[0687] Step 1802: SN1 sends an S-NODE Addition Request Acknowledge message to MN. SN1 adds Mobility Information to this message. Mobility Information refers to a numerical identifier generated by SN and associated with the configuration parameters in SN used to determine changes to SN. SN can use this identifier to locate the configuration parameters in SN used to determine changes to SN.

[0688] Step 1803: Due to a change in the radio signal quality of SN1, and SN1 failing to initiate a timely SN change process to another SN, the UE experiences an SCG radio connection failure on SN1. The UE sends an NR RRC message SCGFailureInformation to the MN. This message contains one or more combinations of the following information:

[0689] SN information (i.e., SN1) indicating an SCG wireless connection failure;

[0690] Source SN information during the last SN change;

[0691] The cell identifier of a cell of an SN suitable for UE access after the UE reports an SCG failure. Optionally, it may also include the TAC and PLMN identifiers of the cell, or TAI;

[0692] The interval between the last SN change process and the SCG wireless connection failure;

[0693] The type of SCG wireless connection failure is radio link failure;

[0694] The identifier C-RNTI assigned to the UE by the SN when an SCG radio connection failure occurs;

[0695] The identifier C-RNTI assigned to the UE by the source SN during the last SN change process;

[0696] The identifier C-RNTI assigned by the MN to the UE;

[0697] UE measurement report.

[0698] The SN information includes the Cell ID of the PSCell, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs.

[0699] Step 1804: MN can select SN2 as the SN suitable for UE access based on the cell of the SN suitable for access after the failure reported by the UE, and / or the measurement report of the UE.

[0700] If the SCGFailureInformation message only carries the SN information of the SCG radio connection failure, or if the source SN information during the last SN change is the same as the SN information of the SN that caused the SCG radio connection failure, and the suitable SN for access is different from the SN that caused the SCG radio connection failure, and the type of SCG radio connection failure is radio link failure, the MN can determine that the type of SN change failure is SN change too late.

[0701] Step 1805: The MN sends a first message to the SN (SN1) where the SCG wireless connection failed. The first message can be either the Xn message Failure Indication or the newly defined Xn message SCG Failure Indication.

[0702] The message contains one or more combinations of the following information:

[0703] The SCG failure information;

[0704] The type of failure when changing SN could be SN change too late;

[0705] A symbol indicating that the SN change process was decided by the SN;

[0706] The node information of the SN includes one or more combinations of the following information:

[0707] The node ID of the node may optionally include the TAC and PLMN identifiers to which the node belongs, or the TAI;

[0708] The PSCell ID of the SN may optionally include the TAC and PLMN identifiers, or TAI, to which the cell belongs;

[0709] The identifier assigned to the UE by the SN when the SCG radio connection fails. This identifier can be the S-NG-RAN node UE XnAP ID identified in the Xn message, or it can be the C-RNTI.

[0710] The identifier assigned to the UE by the MN. This identifier can be the M-NG-RAN node UE XnAP ID in the Xn message, or it can be the C-RNTI.

[0711] The type of SCG wireless connection failure could be radio link failure;

[0712] The source SN information that the SN changes;

[0713] SN information indicating an SCG wireless connection failure;

[0714] SN information suitable for access after wireless connection failure;

[0715] Mobility Information.

[0716] The SN information is the Cell ID of the PSCell, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs. The SN information suitable for access includes the Cell ID of the cell to which it belongs, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs.

[0717] Since SN1 decides whether to initiate the SN change process, and SN1 can determine the type of SN change failure based on the information received, SN1 can use this information to optimize the parameters used to generate the SN change decision, thereby reducing or avoiding the recurrence of similar errors.

[0718] Figure 19 Embodiment 10 according to this disclosure is illustrated schematically.

[0719] In this embodiment, whether to initiate the SN change process is determined by the SN. MN, SN1, SN2, and SN3 are all gNB. Detailed descriptions of some steps that may obscure the subject matter of this invention are omitted here.

[0720] Step 1901: MN configures the UE's SN to SN1.

[0721] Step 1902: SN1 initiates the SN change process from SN1 to SN2.

[0722] During this process, SN1 adds a "MobilityInformation" message to the S-NODE Change Required message. This Mobility Information refers to a numerical identifier generated by the SN and associated with the configuration parameters within the SN used to determine SN changes. The SN can use this identifier to locate the configuration parameters within the SN that determine SN changes.

[0723] Step 1903: The UE experiences an SCG radio connection failure on SN2. The UE sends an NR RRC message SCGFailureInformation to the MN. This message contains one or more combinations of the following information:

[0724] SN information (i.e., SN2) indicating an SCG wireless connection failure;

[0725] The source SN information (i.e., SN1) during the last SN change process;

[0726] The cell identifier of a cell of an SN suitable for UE access after the UE reports an SCG failure. Optionally, it may also include the TAC and PLMN identifiers of the cell, or TAI;

[0727] The interval between the last SN change process and the SCG wireless connection failure;

[0728] The type of SCG wireless connection failure is radio link failure;

[0729] The identifier C-RNTI assigned to the UE by the SN when an SCG radio connection failure occurs;

[0730] The identifier C-RNTI assigned to the UE by the source SN during the last SN change process;

[0731] The identifier C-RNTI assigned by the MN to the UE;

[0732] UE measurement report.

[0733] The SN information includes the Cell ID of the PSCell, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs.

[0734] Step 1904: MN can select SN3 as the SN suitable for UE access based on the cell of the SN suitable for access after the failure reported by the UE, and / or the measurement report of the UE.

[0735] SN3 can be the same as SN1.

[0736] If the SCG radio connection failure type is SN change failure, or the interval between the last SN change process and the SCG radio connection failure is less than a preset threshold, and SN2 is different from SN1 and SN3, MN can determine that the SN change failure type is either SN change too early or change to the wrong SN cell. If SN1 and SN3 are the same, the SN change failure type is SN change too early; if SN1 and SN3 are different, the SN change failure type is change to the wrong SN cell.

[0737] Step 1905: MN sends a first message to SN2, the SN where the SCG wireless connection failed. The first message can be either the Xn message Failure Indication or the newly defined Xn message SCG Failure Indication.

[0738] The message contains one or more combinations of the following information:

[0739] The SCG failure information;

[0740] The types of SN change failures can be either SN change too early or SN change to the wrong cell;

[0741] A symbol indicating that this SN change process was determined by the SN;

[0742] The node information of the SN (i.e., SN1) includes one or more combinations of the following information:

[0743] The node ID of the node may optionally include the TAC and PLMN identifiers to which the node belongs, or the TAI;

[0744] The PSCell ID of the SN may optionally include the TAC and PLMN identifiers, or TAI, to which the cell belongs;

[0745] An identifier assigned to the UE by the SN when an SCG radio connection failure occurs. This identifier can be the S-NG-RAN node UE XnAP ID identified in the Xn message, or it can be the C-RNTI.

[0746] The identifier assigned to the UE by the source SN during the last SN change process; the identifier may be C-RNTI.

[0747] The identifier assigned to the UE by the MN. This identifier can be the M-NG-RAN node UE XnAP ID in the Xn message, or it can be the C-RNTI.

[0748] The types of SCG wireless connection failures can be SN change failure or radio link failure.

[0749] The source SN information that the SN changes;

[0750] SN information indicating an SCG wireless connection failure;

[0751] SN information suitable for access after wireless connection failure;

[0752] The interval between the last SN change process and the SCG wireless connection failure;

[0753] Mobility Information.

[0754] The SN information is the Cell ID of the PSCell, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs. The SN information suitable for access includes the Cell ID of the cell to which it belongs, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs.

[0755] If MN does not send the SN change failure type, or SN2 ignores the SN change failure type sent by MN, SN2 can determine the SN change failure type itself according to the method in step 1904 based on the received information.

[0756] Step 1906: The previous message indicated that the SN change process was determined by SN1, therefore SN2 sends a second message to SN1. The second message can be either the Xn message Handover Report or the newly defined Xn message SCG Change Report.

[0757] The message contains one or more combinations of the following information:

[0758] The SCG failure information;

[0759] The types of SN change failures can be either SN change too early or SN change to the wrong cell;

[0760] The identifier assigned to the UE by the source SN during the SN change process. This identifier can be a C-RNTI.

[0761] The source SN information that the SN changes;

[0762] SN information indicating an SCG wireless connection failure;

[0763] SN information suitable for access after wireless connection failure;

[0764] The types of SCG wireless connection failures can be SN change failure or radio link failure.

[0765] The interval between the last SN change process and the SCG wireless connection failure;

[0766] Mobility Information.

[0767] The SN information is the Cell ID of the PSCell, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs. The SN information suitable for access includes the Cell ID of the cell to which it belongs, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs.

[0768] SN1 can determine the type of SN change failure based on the type of SN change failure determined by SN2, or by itself. SN1 can find and optimize the configuration parameters used to make the decision to change the SN based on the identifier assigned to the UE by the source SN during the SN change process and / or Mobility Information, thereby reducing or even avoiding subsequent SN change failures.

[0769] Figure 20 Embodiment eleven according to this disclosure is illustrated schematically.

[0770] In this embodiment, whether to initiate the SN change process is determined by the SN. MN is an eNB, and SN1 and SN2 are both ng-gNBs. Detailed descriptions of some steps that may obscure the subject matter of this invention are omitted here.

[0771] Step 2001: MN sends an SgNB Addition Request message to SN1.

[0772] Step 2002: SN1 sends an SgNB Addition Request Acknowledge message to MN. SN1 adds Mobility Information to this message. Mobility Information refers to a numerical identifier generated by SN and associated with the configuration parameters in SN used to determine SN changes. SN can use this identifier to locate the configuration parameters in SN used to determine SN changes.

[0773] Step 2003: Due to a change in the radio signal quality of SN1, and SN1 failing to initiate a timely SN change process to another SN, the UE experiences an SCG radio connection failure on SN1. The UE sends an EUTRAN RRC message SCGFailureInformationNR to the MN. This message contains one or more combinations of the following information:

[0774] SN information (i.e., SN1) indicating an SCG wireless connection failure;

[0775] Source SN information during the last SN change;

[0776] The cell identifier of a cell of an SN suitable for UE access after the UE reports an SCG failure. Optionally, it may also include the TAC and PLMN identifiers of the cell, or TAI;

[0777] The interval between the last SN change process and the SCG wireless connection failure;

[0778] The type of SCG wireless connection failure is radio link failure;

[0779] The identifier C-RNTI assigned to the UE by the SN when an SCG radio connection failure occurs;

[0780] The identifier C-RNTI assigned to the UE by the source SN during the last SN change process;

[0781] The identifier C-RNTI assigned by the MN to the UE;

[0782] UE measurement report.

[0783] The SN information includes the Cell ID of the PSCell, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs.

[0784] Step 2004: MN can select SN2 as the SN suitable for UE access based on the cell of the SN suitable for access after the failure reported by the UE, and / or the measurement report of the UE.

[0785] If the SCGFailureInformationNR message only carries the SN information of the SCG radio connection failure, or if the source SN information during the last SN change is the same as the SN information of the SN that caused the SCG radio connection failure, and the suitable SN for access is different from the SN that caused the SCG radio connection failure, and the type of SCG radio connection failure is radio link failure, the MN can determine that the type of SN change failure is SN change too late.

[0786] Step 2005: The MN sends a first message to the SN (SN1) where the SCG wireless connection failed. The first message can be either the X2 message RLF Indication or the newly defined X2 message SCG Failure Indication.

[0787] The message contains one or more combinations of the following information:

[0788] The SCG failure information;

[0789] The type of failure when changing SN could be SN change too late;

[0790] A symbol indicating that the SN change process was decided by the SN;

[0791] The node information of the SN includes one or more combinations of the following information:

[0792] The node ID of the node may optionally include the TAC and PLMN identifiers to which the node belongs, or the TAI;

[0793] The PSCell ID of the SN may optionally include the TAC and PLMN identifiers, or TAI, to which the cell belongs;

[0794] The identifier assigned to the UE by the SN when the SCG radio connection fails. This identifier can be the SgNBUE X2AP ID identified in the X2 message, or it can be the C-RNTI.

[0795] The identifier assigned to the UE by the MN. This identifier can be the MgNB UE X2AP ID identified in the X2 message, or it can be the C-RNTI.

[0796] The type of SCG wireless connection failure could be radio link failure;

[0797] The source SN information that the SN changes;

[0798] SN information indicating an SCG wireless connection failure;

[0799] SN information suitable for access after wireless connection failure;

[0800] Mobility Information.

[0801] The SN information is the Cell ID of the PSCell, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs. The SN information suitable for access includes the Cell ID of the cell to which it belongs, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs.

[0802] Since SN1 decides whether to initiate the SN change process, and SN1 can determine the type of SN change failure based on the information received, SN1 can use this information to optimize the parameters used to generate the SN change decision, thereby reducing or avoiding the recurrence of similar errors.

[0803] Figure 21 Embodiment twelve according to this disclosure is illustrated schematically.

[0804] In this embodiment, whether to initiate the SN change process is determined by the SN. MN is an eNB, and SN1, SN2, and SN3 are all en-gNBs. Detailed descriptions of some steps that may obscure the subject matter of this invention are omitted here.

[0805] Step 2101: MN configures the UE's SN to SN1.

[0806] Step 2102: SN1 initiates the SN change process from SN1 to SN2.

[0807] During this process, SN1 adds a "MobilityInformation" message to the SgNB Change Required message. This Mobility Information refers to a numerical identifier generated by the SN and associated with the configuration parameters within the SN used to determine SN changes. The SN can use this identifier to locate the configuration parameters within the SN that determine SN changes.

[0808] Step 2103: The UE experiences an SCG radio connection failure on SN2. The UE sends an EUTRAN RRC message SCGFailureInformationNR to the MN. This message contains one or more combinations of the following information:

[0809] SN information (i.e., SN2) indicating an SCG wireless connection failure;

[0810] The source SN information (i.e., SN1) during the last SN change process;

[0811] The cell identifier of a cell of an SN suitable for UE access after the UE reports an SCG failure. Optionally, it may also include the TAC and PLMN identifiers of the cell, or TAI;

[0812] The interval between the last SN change process and the SCG wireless connection failure;

[0813] The type of SCG wireless connection failure is radio link failure;

[0814] The identifier C-RNTI assigned to the UE by the SN when an SCG radio connection failure occurs;

[0815] The identifier C-RNTI assigned to the UE by the source SN during the last SN change process;

[0816] The identifier C-RNTI assigned by the MN to the UE;

[0817] UE measurement report.

[0818] The SN information includes the Cell ID of the PSCell, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs.

[0819] Step 2104: MN can select SN3 as the SN suitable for UE access based on the cell of the SN suitable for access after the failure reported by the UE, and / or the measurement report of the UE.

[0820] SN3 can be the same as SN1.

[0821] If the SCG radio connection failure type is SN change failure, or the interval between the last SN change process and the SCG radio connection failure is less than a preset threshold, and SN2 is different from SN1 and SN3, MN can determine that the SN change failure type is either SN change too early or change to the wrong SN cell. If SN1 and SN3 are the same, the SN change failure type is SN change too early; if SN1 and SN3 are different, the SN change failure type is change to the wrong SN cell.

[0822] Step 2105: MN sends a first message to SN2, the SN where the SCG wireless connection failed. The first message can be either the X2 message RLF Indication or the newly defined X2 message SCG Failure Indication.

[0823] The message contains one or more combinations of the following information:

[0824] The SCG failure information;

[0825] The types of SN change failures can be either SN change too early or SN change to the wrong cell;

[0826] A symbol indicating that this SN change process was determined by the SN;

[0827] The node information of the SN (i.e., SN1) includes one or more combinations of the following information:

[0828] The node ID of the node may optionally include the TAC and PLMN identifiers to which the node belongs, or the TAI;

[0829] The PSCell ID of the SN may optionally include the TAC and PLMN identifiers, or TAI, to which the cell belongs;

[0830] The identifier assigned to the UE by the SN when the SCG radio connection fails. This identifier can be the SgNBUE X2AP ID identified in the X2 message, or it can be the C-RNTI.

[0831] The identifier assigned to the UE by the source SN during the last SN change process; the identifier may be C-RNTI.

[0832] The identifier assigned to the UE by the MN. This identifier can be the MeNB UE X2AP ID identified in the X2 message, or it can be the C-RNTI;

[0833] The types of SCG wireless connection failures can be SN change failure or radio link failure.

[0834] The source SN information that the SN changes;

[0835] SN information indicating an SCG wireless connection failure;

[0836] SN information suitable for access after wireless connection failure;

[0837] The interval between the last SN change process and the SCG wireless connection failure;

[0838] Mobility Information.

[0839] The SN information is the Cell ID of the PSCell, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs. The SN information suitable for access includes the Cell ID of the cell to which it belongs, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs.

[0840] If MN does not send the SN change failure type, or SN2 ignores the SN change failure type sent by MN, SN2 can determine the SN change failure type on its own according to the method in step 2104 based on the received information.

[0841] Step 2106: The previous message indicated that the SN change process was determined by SN1, therefore SN2 sends a second message to SN1. The second message can be either the X2 message Handover Report or the newly defined X2 message SCG Change Report.

[0842] The message contains one or more combinations of the following information:

[0843] The SCG failure information;

[0844] The types of SN change failures can be either SN change too early or SN change to the wrong cell;

[0845] The identifier assigned to the UE by the source SN during the SN change process. This identifier can be a C-RNTI.

[0846] The source SN information that the SN changes;

[0847] SN information indicating an SCG wireless connection failure;

[0848] SN information suitable for access after wireless connection failure;

[0849] The types of SCG wireless connection failures can be SN change failure or radio link failure.

[0850] The interval between the last SN change process and the SCG wireless connection failure;

[0851] Mobility Information.

[0852] The SN information is the Cell ID of the PSCell, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs. The SN information suitable for access includes the Cell ID of the cell to which it belongs, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs.

[0853] SN1 can determine the type of SN change failure based on the type of SN change failure determined by SN2, or by itself. SN1 can find and optimize the configuration parameters used to make the decision to change the SN based on the identifier assigned to the UE by the source SN during the SN change process and / or Mobility Information, thereby reducing or even avoiding subsequent SN change failures.

[0854] Figure 22 Embodiment thirteen according to this disclosure is illustrated schematically.

[0855] In this embodiment, whether to initiate the SN change process is determined by the SN. MN, SN1, and SN2 are all gNB. Detailed descriptions of some steps that may obscure the subject matter of this invention are omitted here.

[0856] Step 2201: MN sends an S-Node Addition Request message to SN1.

[0857] Step 2202: SN1 sends an S-Node Addition Request Acknowledge message to MN. SN1 adds Mobility Information to this message. Mobility Information refers to a numerical identifier generated by the SN and associated with the configuration parameters in the SN used to determine SN changes. The SN can use this identifier to locate the configuration parameters in the SN used to determine SN changes. Additionally, SN1 reports the PSCell ID and its PLMN to the MN. The MN can determine the Tracking Area Code of the cell based on the information exchanged between the MN and SN1 during the Xn Setup process.

[0858] The MN adds the information of SN1 to the list of SNs connected to the UE in the UE History Information stored by the MN. This list may include information about one or more SNs connected to the UE. The information about the SNs connected to the UE may include the SN's identifier, and / or the duration of the UE's connection to that SN, and / or the reason the UE's SN is configured as that SN, and / or the associated MN identifier. The SN's identifier may include the PSCell ID, and optionally, may also include the TAC and PLMN identifiers, or TAI, and / or the node ID to which the cell belongs. The MN's identifier may be the PCell ID, and / or the MN node ID. Optionally, the MN may save this list as a separate information section instead of adding it to the UE History Information.

[0859] Step 2203: Due to a change in the radio signal quality of SN1, and SN1 failing to initiate a timely SN change process to another SN, the UE experiences an SCG radio connection failure on SN1. The UE sends an NR RRC message SCGFailureInformation to the MN, which includes the UE's measurement report.

[0860] Step 2204: The MN can select SN2 as the suitable SN for the UE to access based on the UE's measurement report. As described in step 2201, the MN adds the information of SN2 to the list of SNs connected to by the UE stored in the MN. Therefore, the MN can know the suitable SN information for access.

[0861] The MN learns from the SCGFailureInformation that an SCG radio connection failure occurred on the previous SN configured for the UE. It can also obtain information about the SN (SN1), its PSCell Cell ID, and the TAC and PLMN identifiers (or TAI) of that cell from the saved list of SNs connected to the UE. Therefore, the MN can determine the SN information where the SCG radio connection failure occurred, and this SN information should also be the source SN information from which the SN change occurred. Furthermore, the suitable SN for access is different from the SN where the SCG radio connection failure occurred.

[0862] Furthermore, since the MN did not initiate the SN change process, nor did it receive the signaling for the SN change process initiated by the SN, the MN can determine that the type of SCG wireless connection failure is radio link failure.

[0863] Based on the above information, MN can determine that the type of SN change failure is that SN was changed too late.

[0864] Step 2205: The MN sends a first message to the SN (SN1) where the SCG wireless connection failed. The first message can be either the Xn message Failure Indication or the newly defined Xn message SCG Failure Indication.

[0865] The message contains one or more combinations of the following information:

[0866] The SCG failure information;

[0867] The type of failure when changing SN could be SN change too late;

[0868] A symbol indicating that the SN change process was decided by the SN;

[0869] The node information of the SN (i.e., SN1) includes one or more combinations of the following information:

[0870] The node ID of the node may optionally include the TAC and PLMN identifiers to which the node belongs, or the TAI;

[0871] The PSCell ID of the SN may optionally include the TAC and PLMN identifiers, or TAI, to which the cell belongs;

[0872] The identifier assigned to the UE by the SN when the SCG radio connection fails. This identifier can be the SgNBUE X2AP ID identified in the X2 message, or it can be the C-RNTI.

[0873] The identifier assigned to the UE by the MN. This identifier can be the MgNB UE X2AP ID identified in the Xn message, or it can be a C-RNTI;

[0874] The type of SCG wireless connection failure could be radio link failure;

[0875] The source SN information that the SN changes;

[0876] SN information indicating an SCG wireless connection failure;

[0877] SN information suitable for access after wireless connection failure;

[0878] Mobility Information;

[0879] Information list of SNs to which the UE is connected, or UE history information containing information list of SNs to which the UE is connected.

[0880] The SN information is the Cell ID of the PSCell, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs. The SN information suitable for access includes the Cell ID of the cell to which it belongs, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs.

[0881] SN1 can also determine the source SN information of the SN change, and / or the SN information of the SCG radio connection failure, and / or the SN information suitable for access after the radio connection failure, based on the information list of the SNs connected to the UE.

[0882] If MN does not send the SN change failure type, or SN1 ignores the SN change failure type sent by MN, SN1 can determine the SN change failure type itself according to the method in step 2203 based on the received information.

[0883] Since SN1 decides whether to initiate the SN change process, and SN1 can determine the type of SN change failure based on the information received, SN1 can use this information to optimize the parameters used to generate the SN change decision, thereby reducing or avoiding the recurrence of similar errors.

[0884] Figure 23 Embodiment fourteen according to this disclosure is illustrated schematically.

[0885] In this embodiment, whether to initiate the SN change process is determined by the SN. MN, SN1, SN2, and SN3 are all gNB. Detailed descriptions of some steps that may obscure the subject matter of this invention are omitted here.

[0886] Step 2301: The MN configures the UE's SN to SN1. During the SN addition process of Xn, SN1 reports the PSCell ID and its PLMN to the MN. The MN can determine the TrackingArea Code of the cell based on the information exchanged between the MN and SN1 during the Xn Setup process.

[0887] The MN adds the information of SN1 to the list of SNs connected to the UE in the UE History Information stored by the MN. This list may include information about one or more SNs connected to the UE. The information about the SNs connected to the UE may include the SN's identifier, and / or the duration of the UE's connection to that SN, and / or the reason the UE's SN is configured as that SN, and / or the associated MN identifier. The SN's identifier may include the PSCell ID, and optionally, may also include the TAC and PLMN identifiers, or TAI, and / or the node ID to which the cell belongs. The MN's identifier may be the PCell ID, and / or the MN node ID. Optionally, the MN may save this list as a separate information section instead of adding it to the UE History Information.

[0888] Step 2302: SN1 initiates the SN change process from SN1 to SN2. As described in step 2301, MN adds the information of SN2 to the list of information of the SNs to which the UE is connected, which is stored in MN.

[0889] During this process, SN1 adds a "MobilityInformation" message to the SgNB Change Required message. This Mobility Information refers to a numerical identifier generated by the SN and associated with the configuration parameters within the SN used to determine SN changes. The SN can use this identifier to locate the configuration parameters within the SN that determine SN changes.

[0890] Step 2303: The UE experiences an SCG radio connection failure on SN2. The UE sends an NR RRC message SCGFailureInformation to the MN. This message includes the UE's measurement report.

[0891] Step 2304: The MN can select SN3 as the suitable SN for the UE to access based on the UE's measurement report. As described in step 2301, the MN adds the information of SN3 to the list of SNs connected to by the UE stored in the MN. Therefore, the MN can know the suitable SN information for access.

[0892] SN3 can be the same as SN1.

[0893] The MN learns from the SCGFailureInformation that an SCG radio connection failure occurred on the previous SN configured for the UE. It can also obtain information about the SN (SN2), its PSCell Cell ID, and the TAC and PLMN identifiers (or TAI) of that cell from the saved list of SNs connected to the UE. Therefore, the MN can determine the SN information where the SCG radio connection failure occurred. Furthermore, the MN initiates an SN change process; therefore, the SN configured for the UE before SN2 is the source SN for the SN change. The MN can obtain information about the SN (SN1), its PSCell Cell ID, and the TAC and PLMN identifiers (or TAI) of that cell from the saved list of SNs connected to the UE. Therefore, the MN can determine the source SN information for the SN change.

[0894] If the SN change process is not completed successfully, the MN will receive an SCG failure message reported by the UE. The MN can determine that the type of SCG radio connection failure is SN change failure; otherwise, the type of SCG radio connection failure is radiolink failure.

[0895] The MN can also calculate the interval between the last SN change process and the SCG radio connection failure based on the time of the last SN change process and the SCG failure information received from the UE.

[0896] If the SCG radio connection failure type is SN change failure, or the interval between the last SN change process and the SCG radio connection failure is less than a preset threshold, and SN2 is different from SN1 and SN3, MN can determine that the SN change failure type is either SN change too early or change to the wrong SN cell. If SN1 and SN3 are the same, the SN change failure type is SN change too early; if SN1 and SN3 are different, the SN change failure type is change to the wrong SN cell.

[0897] Step 2305: MN sends a first message to SN2, the SN where the SCG wireless connection failed. The first message can be either the Xn message Failure Indication or the newly defined Xn message SCG Failure Indication.

[0898] The message contains one or more combinations of the following information:

[0899] The SCG failure information;

[0900] The types of SN change failures can be either SN change too early or SN change to the wrong cell;

[0901] A symbol indicating that this SN change process was determined by the SN;

[0902] The node information of the SN (i.e., SN1) includes one or more combinations of the following information:

[0903] The node ID of the node may optionally include the TAC and PLMN identifiers to which the node belongs, or the TAI;

[0904] The PSCell ID of the SN may optionally include the TAC and PLMN identifiers, or TAI, to which the cell belongs;

[0905] An identifier assigned to the UE by the SN when an SCG radio connection failure occurs. This identifier may be the S-NG-RAN node UE XnAP ID identified in the Xn message.

[0906] The identifier assigned to the UE by the MN. This identifier can be the M-NG-RAN node UE XnAP ID in the Xn message, or it can be the C-RNTI.

[0907] The types of SCG wireless connection failures can be SN change failure or radio link failure.

[0908] The source SN information that the SN changes;

[0909] SN information indicating an SCG wireless connection failure;

[0910] SN information suitable for access after wireless connection failure;

[0911] The interval between the last SN change process and the SCG wireless connection failure;

[0912] Information list of SNs to which the UE is connected, or UE history information containing information list of SNs to which the UE is connected;

[0913] Mobility Information.

[0914] The SN information is the Cell ID of the PSCell, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs. The SN information suitable for access includes the Cell ID of the cell to which it belongs, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs.

[0915] If MN does not send the SN change failure type, or SN2 ignores the SN change failure type sent by MN, SN2 can determine the SN change failure type on its own according to the method in step 2304 based on the received information.

[0916] Step 2306: The previous message indicated that the SN change process was determined by SN1, therefore SN2 sends a second message to SN1. The second message can be either the Xn message Handover Report or the newly defined Xn message SCG Change Report.

[0917] The message contains one or more combinations of the following information:

[0918] The SCG failure information;

[0919] The types of SN change failures can be either SN change too early or SN change to the wrong cell;

[0920] The source SN information that the SN changes;

[0921] SN information indicating an SCG wireless connection failure;

[0922] SN information suitable for access after wireless connection failure;

[0923] The types of SCG wireless connection failures can be SN change failure or radio link failure.

[0924] The interval between the last SN change process and the SCG wireless connection failure;

[0925] Mobility Information;

[0926] Information list of SNs to which the UE is connected, or UE history information containing information list of SNs to which the UE is connected.

[0927] The SN information is the Cell ID of the PSCell, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs. The SN information suitable for access includes the Cell ID of the cell to which it belongs, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs.

[0928] SN1 can also determine the source SN information of the SN change, and / or the SN information of the SCG radio connection failure, and / or the SN information suitable for access after the radio connection failure, based on the information list of the SNs connected to the UE.

[0929] If SN2 does not send the type of SN change failure, or SN1 ignores the type of SN change failure sent by SN2, SN1 can determine the type of SN change failure itself according to the method in step 2304 based on the received information.

[0930] SN1 can determine the type of SN change failure based on the type of SN change failure determined by SN2, or by itself. SN1 can find and optimize the configuration parameters used to make the decision to change the SN based on the identifier assigned to the UE by the source SN during the SN change process and / or Mobility Information, thereby reducing or even avoiding subsequent SN change failures.

[0931] Figure 24 Embodiment 15 according to this disclosure is illustrated schematically.

[0932] In this embodiment, whether to initiate the SN change process is determined by the SN. MN is an eNB, and SN1 and SN2 are both en-gNBs. Detailed descriptions of some steps that may obscure the subject matter of this invention are omitted here.

[0933] Step 2401: MN sends an SgNB Addition Request message to SN1.

[0934] Step 2402: SN1 sends an SgNB Addition Request Acknowledge message to MN. SN1 adds Mobility Information to this message. Mobility Information refers to a numerical identifier generated by SN and associated with the configuration parameters in SN used to determine SN changes. SN can use this identifier to locate the configuration parameters in SN used to determine SN changes. SN1 reports the PSCell ID to MN, and MN learns about the PLMN used by SCG. MN can determine the Tracking Area Code of the cell based on the information exchanged between MN and SN1 during the EN-DC Setup process.

[0935] The MN adds the information of SN1 to the list of SNs connected to the UE in the UE History Information stored by the MN. This list may include information about one or more SNs connected to the UE. The information about the SNs connected to the UE may include the SN's identifier, and / or the duration of the UE's connection to that SN, and / or the reason the UE's SN is configured as that SN, and / or the associated MN identifier. The SN's identifier may include the PSCell ID, and optionally, may also include the TAC and PLMN identifiers, or TAI, and / or the node ID to which the cell belongs. The MN's identifier may be the PCell ID, and / or the MN node ID. Optionally, the MN may save this list as a separate information section instead of adding it to the UE History Information.

[0936] Step 2403: Due to a change in the radio signal quality of SN1, and SN1 failing to initiate a timely SN change process to another SN, the UE experiences an SCG radio connection failure on SN1. The UE sends an EUTRAN RRC message SCGFailureInformationNR to the MN. This message includes the UE's measurement report.

[0937] Step 2404: The MN can select SN2 as the suitable SN for the UE to access based on the UE's measurement report. As described in step 2401, the MN adds the information of SN2 to the list of SNs connected to by the UE stored in the MN. Therefore, the MN can know the suitable SN information for access.

[0938] The MN learns from the SCGFailureInformationNR that an SCG radio connection failure occurred on the previous SN configured for the UE. It can also obtain information about the SN (SN1), its PSCell Cell ID, and the TAC and PLMN identifiers (or TAI) of that cell from the saved list of SNs connected to the UE. Therefore, the MN can determine the SN information where the SCG radio connection failure occurred, and this SN information should also be the source SN information from which the SN change occurred. Furthermore, the suitable SN for access is different from the SN where the SCG radio connection failure occurred.

[0939] Furthermore, since the MN did not initiate the SN change process, nor did it receive the signaling for the SN change process initiated by the SN, the MN can determine that the type of SCG wireless connection failure is radio link failure.

[0940] Based on the above information, MN can determine that the type of SN change failure is that SN was changed too late.

[0941] Step 2405: The MN sends a first message to the SN (SN1) where the SCG wireless connection failed. The first message can be an X2 message RLF or a newly defined X2 message SCG Failure Indication.

[0942] The message contains one or more combinations of the following information:

[0943] The SCG failure information;

[0944] The type of failure when changing SN could be SN change too late;

[0945] A symbol indicating that the SN change process was decided by the SN;

[0946] The node information of the SN (i.e., SN1) includes one or more combinations of the following information:

[0947] The node ID of the node may optionally include the TAC and PLMN identifiers to which the node belongs, or the TAI;

[0948] The PSCell ID of the SN may optionally include the TAC and PLMN identifiers, or TAI, to which the cell belongs;

[0949] The identifier assigned to the UE by the SN when the SCG radio connection fails. This identifier can be the SgNBUE X2AP ID identified in the X2 message, or it can be the C-RNTI.

[0950] The identifier assigned to the UE by the MN. This identifier can be the MgNB UE X2AP ID identified in the X2 message, or it can be the C-RNTI.

[0951] The type of SCG wireless connection failure could be radio link failure;

[0952] The source SN information that the SN changes;

[0953] SN information indicating an SCG wireless connection failure;

[0954] SN information suitable for access after wireless connection failure;

[0955] Mobility Information;

[0956] Information list of SNs to which the UE is connected, or UE history information containing information list of SNs to which the UE is connected.

[0957] The SN information is the Cell ID of the PSCell, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs. The SN information suitable for access includes the Cell ID of the cell to which it belongs, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs.

[0958] SN1 can also determine the source SN information of the SN change, and / or the SN information of the SCG radio connection failure, and / or the SN information suitable for access after the radio connection failure, based on the information list of the SNs connected to the UE.

[0959] If MN does not send the SN change failure type, or SN1 ignores the SN change failure type sent by MN, SN1 can determine the SN change failure type itself according to the method in step 2403 based on the received information.

[0960] Since SN1 decides whether to initiate the SN change process, and SN1 can determine the type of SN change failure based on the information received, SN1 can use this information to optimize the parameters used to generate the SN change decision, thereby reducing or avoiding the recurrence of similar errors.

[0961] Figure 25 Embodiment sixteen according to this disclosure is illustrated schematically.

[0962] In this embodiment, whether to initiate the SN change process is determined by the SN. MN is an eNB, and SN1, SN2, and SN3 are all en-gNBs. Detailed descriptions of some steps that may obscure the subject matter of this invention are omitted here.

[0963] Step 2501: The MN configures the UE's SN to SN1. During the SN addition process of X2, SN1 reports the PSCell ID to the MN, and the MN knows the PLMN used by the SCG. The MN can determine the Tracking Area Code of the cell based on the information exchanged between the MN and SN1 during the EN-DC Setup process.

[0964] The MN adds the information of SN1 to the list of SNs connected to the UE in the UE History Information stored by the MN. This list may include information about one or more SNs connected to the UE. The information about the SNs connected to the UE may include the SN's identifier, and / or the duration of the UE's connection to that SN, and / or the reason the UE's SN is configured as that SN, and / or the associated MN identifier. The SN's identifier may include the PSCell ID, and optionally, may also include the TAC and PLMN identifiers, or TAI, and / or the node ID to which the cell belongs. The MN's identifier may be the PCell ID, and / or the MN node ID. Optionally, the MN may save this list as a separate information section instead of adding it to the UE History Information.

[0965] Step 2502: SN1 initiates the SN change process from SN1 to SN2. As described in step 2501, MN adds the information of SN2 to the list of information of the SNs to which the UE is connected, which is stored in MN.

[0966] During this process, SN1 adds a "MobilityInformation" message to the SgNB Change Required message. This Mobility Information refers to a numerical identifier generated by the SN and associated with the configuration parameters within the SN used to determine SN changes. The SN can use this identifier to locate the configuration parameters within the SN that determine SN changes.

[0967] Step 2503: The UE experiences an SCG radio connection failure on SN2. The UE sends an EUTRAN RRC message SCGFailureInformationNR to the MN. This message includes the UE's measurement report.

[0968] Step 2504: The MN can select SN3 as the suitable SN for the UE to access based on the UE's measurement report. As described in step 2501, the MN adds the information of SN3 to the list of SNs connected to by the UE stored in the MN. Therefore, the MN can know the suitable SN information for access.

[0969] SN3 can be the same as SN1.

[0970] The MN learns from the SCGFailureInformationNR that an SCG radio connection failure occurred on the previous SN configured for the UE. It can also obtain information about the SN (SN2), its PSCell Cell ID, and the TAC and PLMN identifiers (or TAI) of that cell from the saved list of SNs connected to the UE. Therefore, the MN can determine the SN information where the SCG radio connection failure occurred. Furthermore, the MN initiates an SN change process; therefore, the SN previously configured for the UE (SN2) is the source SN for the change. The MN can obtain information about the SN (SN1), its PSCell Cell ID, and the TAC and PLMN identifiers (or TAI) of that cell from the saved list of SNs connected to the UE. Therefore, the MN can determine the source SN information for the change.

[0971] If the SN change process is not completed successfully, the MN will receive an SCG failure message reported by the UE. The MN can determine that the type of SCG radio connection failure is SN change failure; otherwise, the type of SCG radio connection failure is radiolink failure.

[0972] The MN can also calculate the interval between the last SN change process and the SCG radio connection failure based on the time of the last SN change process and the SCG failure information received from the UE.

[0973] If the SCG radio connection failure type is SN change failure, or the interval between the last SN change process and the SCG radio connection failure is less than a preset threshold, and SN2 is different from SN1 and SN3, MN can determine that the SN change failure type is either SN change too early or change to the wrong SN cell. If SN1 and SN3 are the same, the SN change failure type is SN change too early; if SN1 and SN3 are different, the SN change failure type is change to the wrong SN cell.

[0974] Step 2505: The MN sends a first message to the SN (SN2) where the SCG wireless connection failed. The first message can be either the X2 message RLF Indication or the newly defined X2 message SCG Failure Indication.

[0975] The message contains one or more combinations of the following information:

[0976] The SCG failure information;

[0977] The types of SN change failures can be either SN change too early or SN change to the wrong cell;

[0978] A symbol indicating that this SN change process was determined by the SN;

[0979] The node information of the SN (i.e., SN1) includes one or more combinations of the following information:

[0980] The node ID of the node may optionally include the TAC and PLMN identifiers to which the node belongs, or the TAI;

[0981] The PSCell ID of the SN may optionally include the TAC and PLMN identifiers, or TAI, to which the cell belongs;

[0982] The identifier assigned to the UE by the SN when the SCG radio connection fails. This identifier may be the SgNBX2AP ID identified in the X2 message;

[0983] The identifier assigned to the UE by the MN. This identifier can be the MeNB UE X2AP ID identified in the X2 message, or it can be the C-RNTI.

[0984] The types of SCG wireless connection failures can be SN change failure or radio link failure.

[0985] The source SN information that the SN changes;

[0986] SN information indicating an SCG wireless connection failure;

[0987] SN information suitable for access after wireless connection failure;

[0988] The interval between the last SN change process and the SCG wireless connection failure;

[0989] Information list of SNs to which the UE is connected, or UE history information containing information list of SNs to which the UE is connected;

[0990] Mobility Information.

[0991] The SN information is the Cell ID of the PSCell, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs. The SN information suitable for access includes the Cell ID of the cell to which it belongs, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs.

[0992] If MN does not send the SN change failure type, or SN2 ignores the SN change failure type sent by MN, SN2 can determine the SN change failure type on its own according to the method in step 2504 based on the received information.

[0993] Step 2506: The previous message indicated that the SN change process was determined by SN1, therefore SN2 sends a second message to SN1. The second message can be either the X2 message Handover Report or the newly defined X2 message SCG Change Report.

[0994] The message contains one or more combinations of the following information:

[0995] The SCG failure information;

[0996] The types of SN change failures can be either SN change too early or SN change to the wrong cell;

[0997] The source SN information that the SN changes;

[0998] SN information indicating an SCG wireless connection failure;

[0999] SN information suitable for access after wireless connection failure;

[1000] The types of SCG wireless connection failures can be SN change failure or radio link failure.

[1001] The interval between the last SN change process and the SCG wireless connection failure;

[1002] Mobility Information;

[1003] Information list of SNs to which the UE is connected, or UE history information containing information list of SNs to which the UE is connected.

[1004] The SN information is the Cell ID of the PSCell, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs. The SN information suitable for access includes the Cell ID of the cell to which it belongs, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs.

[1005] SN1 can also determine the source SN information of the SN change, and / or the SN information of the SCG radio connection failure, and / or the SN information suitable for access after the radio connection failure, based on the information list of the SNs connected to the UE.

[1006] If SN2 does not send the type of SN change failure, or SN1 ignores the type of SN change failure sent by SN2, SN1 can determine the type of SN change failure itself according to the method in step 2504 based on the received information.

[1007] SN1 can determine the type of SN change failure based on the type of SN change failure determined by SN2, or by itself. SN1 can find and optimize the configuration parameters used to make the decision to change the SN based on the identifier assigned to the UE by the source SN during the SN change process and / or Mobility Information, thereby reducing or even avoiding subsequent SN change failures.

[1008] Figure 26 schematically shown Figure 19 Another implementation of Example 10.

[1009] In this embodiment, whether to initiate the SN change process is determined by the SN. MN, SN1, SN2, and SN3 are all gNB. Detailed descriptions of some steps that may obscure the subject matter of this invention are omitted here.

[1010] Steps 2601-2605 are similar to steps 1901-1905.

[1011] Step 2606: SN2 sends a second message to MN.

[1012] The previous message indicated that the SN change process was determined by SN1. SN2 can send a second message to MN, which is then forwarded to SN1 by MN. The second message can be either the Xn message Handover Report or the newly defined Xn message SCG ChangeReport.

[1013] The message contains one or more combinations of the following information:

[1014] The SCG failure information;

[1015] The types of SN change failures can be either SN change too early or SN change to the wrong cell;

[1016] The identifier assigned to the UE by the source SN during the SN change process. This identifier can be a C-RNTI.

[1017] The source SN information that the SN changes;

[1018] SN information indicating an SCG wireless connection failure;

[1019] SN information suitable for access after wireless connection failure;

[1020] The types of SCG wireless connection failures can be SN change failure or radio link failure.

[1021] The interval between the last SN change process and the SCG wireless connection failure;

[1022] Mobility Information.

[1023] Wherein, the SN information is the Cell ID of the PSCell, and optionally, it may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs. The SN information suitable for access includes the Cell ID of the cell to which it belongs, and optionally, it may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs. Optionally, the source SN information from which the SN changes may also include the Node ID of the node, and optionally, it includes the TAC and PLMN identifiers, or TAI, to which the node belongs.

[1024] Step 2607: MN determines that the received message should be forwarded to SN1 based on the source SN information changed by SN. MN sends a third message to SN1 to forward the content of the second message to SN1. The second message can be an Xn message Handover Report or a newly defined Xn message SCG Change Report.

[1025] MN can change the failure type by modifying SN according to its own judgment.

[1026] SN1 can accept the type of SN change failure determined in the third message, or determine the type of SN change failure on its own. SN1 can find and optimize the configuration parameters used to make the decision to change the SN based on the identifier assigned to the UE by the source SN during the SN change process and / or Mobility Information, thereby reducing or even avoiding subsequent SN change failures.

[1027] Figure 27 schematically shown Figure 19 Another implementation of Example 10.

[1028] In this embodiment, whether to initiate the SN change process is determined by the SN. MN, SN1, SN2, and SN3 are all gNBs. There is no Xn interface between SN1 and SN2, and SN1 and SN2 are connected to CN. Detailed descriptions of some steps that may obscure the subject matter of this invention are omitted here.

[1029] Steps 2701-2705 are similar to steps 1901-1905.

[1030] Step 2706: SN2 sends a second message to CN.

[1031] The previous message indicated that the SN change process was determined by SN1. SN2 can send a second message to CN, which will then forward it to SN1. The second message can be an Ng message (Uplink RAN ​​Configuration Transfer) or a newly defined Ng message.

[1032] The message contains one or more combinations of the following information:

[1033] The SCG failure information;

[1034] The types of SN change failures can be either SN change too early or SN change to the wrong cell;

[1035] The identifier assigned to the UE by the source SN during the SN change process. This identifier can be a C-RNTI.

[1036] The source SN information that the SN changes;

[1037] SN information indicating an SCG wireless connection failure;

[1038] SN information suitable for access after wireless connection failure;

[1039] The types of SCG wireless connection failures can be SN change failure or radio link failure.

[1040] The interval between the last SN change process and the SCG wireless connection failure;

[1041] Mobility Information.

[1042] Wherein, the SN information is the Cell ID of the PSCell, and optionally, it may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs. The SN information suitable for access includes the Cell ID of the cell to which it belongs, and optionally, it may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs. Optionally, the source SN information from which the SN changes may also include the Node ID of the node, and optionally, it includes the TAC and PLMN identifiers, or TAI, to which the node belongs.

[1043] Step 2707: The CN can determine the address of SN1 based on the node ID, or PSCell ID, and TAC and PLMN identifiers, or TAI, in the source SN information that the SN has changed. The CN sends a third message to SN1, forwarding the content of the second message to SN1. The third message can be an Ng message (Downlink RAN ​​Configuration Transfer) or a newly defined Ng message.

[1044] SN1 can determine the type of SN change failure based on the type of SN change failure determined by SN2, or by itself. SN1 can find and optimize the configuration parameters used to make the decision to change the SN based on the identifier assigned to the UE by the source SN during the SN change process and / or Mobility Information, thereby reducing or even avoiding subsequent SN change failures.

[1045] Figure 28 schematically shown Figure 25 Another implementation of Example Sixteen.

[1046] In this embodiment, whether to initiate the SN change process is determined by the SN. MN, SN1, SN2, and SN3 are all gNBs. There is no Xn interface between SN1 and SN2, and SN1 and SN2 are connected to CN. Detailed descriptions of some steps that may obscure the subject matter of this invention are omitted here.

[1047] Steps 2801-2805 are similar to steps 2501-2505.

[1048] Step 2806: SN2 sends a second message to CN.

[1049] The previous message indicated that the SN change process was determined by SN1. SN2 can send a second message to CN, which will then forward it to SN1. The second message can be an Ng message (Uplink RAN ​​Configuration Transfer) or a newly defined Ng message.

[1050] The message contains one or more combinations of the following information:

[1051] The SCG failure information;

[1052] The types of SN change failures can be either SN change too early or SN change to the wrong cell;

[1053] The source SN information that the SN changes;

[1054] SN information indicating an SCG wireless connection failure;

[1055] SN information suitable for access after wireless connection failure;

[1056] The types of SCG wireless connection failures can be SN change failure or radio link failure.

[1057] The interval between the last SN change process and the SCG wireless connection failure;

[1058] Mobility Information;

[1059] Information list of SNs to which the UE is connected, or UE history information containing information list of SNs to which the UE is connected.

[1060] Wherein, the SN information is the Cell ID of the PSCell, and optionally, it may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs. The SN information suitable for access includes the Cell ID of the cell to which it belongs, and optionally, it may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs. Optionally, the source SN information from which the SN changes may also include the Node ID of the node, and optionally, it includes the TAC and PLMN identifiers, or TAI, to which the node belongs.

[1061] Step 2807: The CN can determine the address of SN1 based on the node ID, or PSCell ID, and TAC and PLMN identifiers, or TAI, in the source SN information that the SN has changed. The CN sends a third message to SN1, forwarding the content of the second message to SN1. The third message can be an Ng message (Downlink RAN ​​Configuration Transfer) or a newly defined Ng message.

[1062] SN1 can also determine the source SN information of the SN change, and / or the SN information of the SCG radio connection failure, and / or the SN information suitable for access after the radio connection failure, based on the information list of the SNs connected to the UE.

[1063] If SN2 does not send the type of SN change failure, or SN1 ignores the type of SN change failure sent by SN2, SN1 can determine the type of SN change failure itself according to the method in step 2304 based on the received information.

[1064] SN1 can determine the type of SN change failure based on the SN2 judgment, or determine the type of SN change failure on its own. SN1 can find and optimize the configuration parameters used to make the decision to change the SN based on Mobility Information, thereby reducing or even avoiding subsequent SN change failures.

[1065] Figure 29 schematically shown Figure 19 Another implementation of Example 10.

[1066] In this embodiment, whether to initiate the SN change process is determined by the SN. MN, SN1, SN2, and SN3 are all gNB. Detailed descriptions of some steps that may obscure the subject matter of this invention are omitted here.

[1067] Steps 2901-2904 are similar to steps 1901-1904.

[1068] Step 2905: MN sends a first message to the SN that initiated the SN change process, i.e., SN1. The first message can be an Xn message Handover Report or a newly defined Xn message SCG Change Report.

[1069] The message contains one or more combinations of the following information:

[1070] The SCG failure information;

[1071] The types of SN change failures can be either SN change too early or SN change to the wrong cell;

[1072] The identifier assigned to the UE by the source SN during the SN change process. This identifier can be a C-RNTI.

[1073] The source SN information that the SN changes;

[1074] SN information indicating an SCG wireless connection failure;

[1075] SN information suitable for access after wireless connection failure;

[1076] The types of SCG wireless connection failures can be SN change failure or radio link failure.

[1077] The interval between the last SN change process and the SCG wireless connection failure;

[1078] Mobility Information.

[1079] The SN information is the Cell ID of the PSCell, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs. The SN information suitable for access includes the Cell ID of the cell to which it belongs, and optionally may also include the TAC and PLMN identifiers, or TAI, to which the Cell belongs.

[1080] SN1 can determine the type of SN change failure based on the MN, or determine the type of SN change failure on its own. SN1 can find and optimize the configuration parameters used to make the decision to change the SN based on the identifier assigned to the UE by the source SN during the SN change process and / or Mobility Information, thereby reducing or even avoiding subsequent SN change failures.

[1081] Figure 30 schematically shown Figure 22 Another implementation of Example Thirteen.

[1082] In this embodiment, whether to initiate the SN change process is determined by the SN. MN, SN1, and SN2 are all gNB. Detailed descriptions of some steps that may obscure the subject matter of this invention are omitted here.

[1083] Step 3001: MN sends an S-Node Addition Request message to SN1. This message may carry the information "Location Information at S-NODE reporting," with the value "pscell," requesting SN1 to report the information of the PSCell selected by SN1, regardless of whether the core network entity requests MN to report the UE's location information.

[1084] Step 3002: SN1 sends an S-Node Addition Request Acknowledge message to MN. This message may carry Location Information at S-NODE, reporting the information of the PSCell selected by SN1 to MN, regardless of whether MN requests this information from SN1. MN can determine the TAC of the cell based on the information exchanged between MN and SN1 during the Xn Setup process.

[1085] SN1 adds a "Mobility Information" field to the message. This Mobility Information is a numerical identifier generated by the SN and associated with the configuration parameters within the SN used to determine changes to the SN. The SN can use this identifier to locate the configuration parameters within the SN that determine changes to the SN.

[1086] The MN adds the information of SN1 to the list of SNs connected to the UE in the UE History Information stored by the MN. This list may include information about one or more SNs connected to the UE. The information about the SNs connected to the UE may include the SN's identifier, and / or the duration of the UE's connection to that SN, and / or the reason the UE's SN is configured as that SN, and / or the associated MN identifier. The SN's identifier may include the PSCell ID, and optionally, may also include the TAC and PLMN identifiers, or TAI, and / or the node ID to which the cell belongs. The MN's identifier may be the PCell ID, and / or the MN node ID. Optionally, the MN may save this list as a separate information section instead of adding it to the UE History Information.

[1087] Steps 3003-3005 are similar to steps 2203-2205.

[1088] Since SN1 decides whether to initiate the SN change process, and SN1 can determine the type of SN change failure based on the information received, SN1 can use this information to optimize the parameters used to generate the SN change decision, thereby reducing or avoiding the recurrence of similar errors.

[1089] Figure 31 Example fourteen is illustrated schematically.

[1090] In this embodiment, MN, SN1, and SN2 can all be gNB. Detailed descriptions of some steps that may obscure the subject matter of this invention are omitted here.

[1091] SN1 is configured as the SN of the UE, and Cell 1 of SN1 is set as the PSCell of the UE.

[1092] Step 3101: SN1 decides to initiate the SN change process. SN1 sends an S-Node Change Required message to MN, requesting that SN2 be configured as the UE's SN. The message includes a list of PSCell information that the UE has connected to, generated by SN1. In this embodiment, the list includes information about Cell 1 of SN1. The information includes the Cell Identifier (NG-RANCell Identity) of Cell 1, the duration of the UE's connection to that Cell, the reason for the PSCell change, and the associated MN identification information. MN saves the PSCell information list and determines that this SN change process was initiated by SN; MN also saves this determination.

[1093] Steps 3102-3103: MN initiates the SN addition process to SN2. In step 3102, MN sends an S-Node addition request message to SN2, and in step 3103, SN2 sends an S-Node addition request confirmation message to MN.

[1094] Step 3104: MN sends an SN change confirmation to SN1.

[1095] After the SN change process is completed, SN2 is configured as the UE's SN, and Cell 2 of SN2 is set as the UE's PSCell.

[1096] During or after an SN change, SN1 may also use a predefined Xn message, such as Access and Mobility Indication, or a newly defined Xn message, such as SN Information Update, to send the list of PSCell information that the UE has connected to, generated by SN1, to MN.

[1097] Steps 3105-3106: Shortly after the last SN change process ends, the MN decides to initiate an SN change process. The MN initiates an SN addition process to SN1, requesting that SN1 be configured as the UE's SN. In step 3105, the MN sends an S-Node addition request message to SN1, and in step 3106, SN1 sends an S-Node addition request confirmation message to the MN.

[1098] Steps 3107-3108: MN initiates an SN release procedure to SN2. In step 3107, MN sends an S-Node release request message to SN2, and in step 3108, SN2 sends an S-Node release request confirmation message to MN. The message includes a list of PSCell information that the UE has connected to, generated by SN2. In this embodiment, the list includes information about Cell 2 of SN2. The information includes at least one of the following: the cell identity (NG-RAN Cell Identity) of Cell 2, the duration of the UE's connection to that Cell, the reason for the PSCell change, and the associated MN identification information. MN saves this PSCell information list and determines that the current SN change procedure was initiated by MN; MN also saves this determination.

[1099] After the SN change process is completed, SN1 is configured as the UE's SN, and Cell 1 of SN1 is set as the UE's PSCell.

[1100] During the UE connection process with SN1, SN1 can use the Xn message to send the MN a list of PSCell information generated by SN1, indicating the UE's previous connections. In this embodiment, the list includes information about Cell 1 of SN1. This information includes the Cell Identifier (NG-RAN Cell Identity) of Cell 1 and the duration of the UE's connection to that Cell. The MN stores this PSCell information list.

[1101] Based on the received PSCell information list, the MN can know that the UE's PSCell changed from Cell 1 to Cell 2 and then back to Cell 1. Furthermore, the duration of the UE's connection to Cell 2 is less than the pre-configured threshold. The MN determines that an SN ChangePing-pong has occurred, and the SN change process from SN1 to SN2 was initiated by the SN.

[1102] Step 3109: MN sends a Handover Report to SN1, in which the error type indicating the SN change is SN Change Ping-pong, and carries a list of PSCell information received by MN.

[1103] SN1 can determine that an SN Change Ping-pong has occurred based on the information it receives. Therefore, SN1 can use this information to optimize the parameters used to generate the SN Change decision, thereby reducing or avoiding the recurrence of similar errors.

[1104] Figure 32 Example 15 is illustrated schematically.

[1105] In this embodiment, MN1, MN2, SN1, SN2, and SN3 are all gNB. Detailed descriptions of some steps that may obscure the subject matter of this invention are omitted here.

[1106] SN1 is configured as the SN of the UE, and Cell 1 of SN1 is set as the PSCell of the UE.

[1107] Step 3201: MN1 decides to initiate a handover process to MN2. MN1 sends a handover request to MN2.

[1108] Steps 3202-3203: MN2 decides to configure SN2 as the UE's SN. MN2 initiates an SN addition procedure to SN2. In step 3202, MN2 sends an S-Node addition request message to SN2, and in step 3203, SN2 sends an S-Node addition request confirmation message to MN2. Cell 2 of SN2 is set as the UE's PSCell.

[1109] Step 3204: MN2 sends a switch confirmation to MN.

[1110] Steps 3205-3206: MN1 initiates an SN release procedure to SN1. In step 3205, MN1 sends an S-Node release request message to SN1. In step 3206, SN1 sends an S-Node release request confirmation message to MN1. The message includes a list of PSCell information that the UE has connected to, generated by SN1. In this embodiment, the list includes information about Cell 1 of SN1. The information includes at least one of the following: the cell identity (NG-RAN Cell Identity) of Cell 1, the duration of the UE's connection to the Cell, the reason for the change of the PSCell, and the associated MN identity information.

[1111] Step 3207: MN1 sends an Access and Mobility Indication message to MN2, which includes a list of PSCell information received by MN1 from the UE that it has connected to. This message can also be other Xn messages, or a newly defined Xn message.

[1112] In step 3201, MN1 can also send the list of PSCell information that the UE has connected to, which it has received, to MN2.

[1113] Shortly after the UE connects to SN2, MN2 or SN2 initiates an SN change procedure, setting SN3 as the UE's SN and SN3's Cell 3 as the UE's PSCell. During this procedure, SN2 sends the list of PSCells that the UE has connected to, generated by SN2, to MN2 as in step 3206.

[1114] Based on the received PSCell information list, MN2 can know that the UE's PSCell changed from Cell 1 to Cell 2, and then to Cell 3. Furthermore, the duration of the UE's connection to Cell 2 is less than the pre-configured threshold. MN2 then determines that an SNChange Ping-pong has occurred.

[1115] Since the process of configuring SN2 as the UE's SN in step 3202 is initiated by MN2, MN2 can optimize the parameters used to generate the SN change decision based on the received information, so as to reduce or avoid similar errors from happening again.

[1116] Figure 33 A block diagram of an access node according to an example embodiment of this application is shown. Figure 33 As shown, access node 3300 includes processor 3301 and memory 3302. Access node 3300 is capable of performing the functions described in any of the embodiments.

[1117] Although this disclosure has been shown and described with reference to various embodiments thereof, those skilled in the art will understand that various changes in form and detail may be made therein without departing from the spirit and scope of this disclosure as defined by the appended claims and their equivalents.

Claims

1. A method for a master node MN in a wireless communication system, the method comprising: Receive a first message that triggers a change in the first secondary node SN, the first message including a first information list of primary and secondary cells PSCells served by the first SN for the user equipment UE; Based on the first message, a second message requesting the second SN to be added to the second SN is sent; Send a third message to the second SN requesting the release of the second SN; as well as The UE receives an acknowledgment message for the third message from the second SN. The acknowledgment message includes a second information list about the PSCell served by the second SN. The second information list includes the cell identifier of the PSCell served by the second SN and the duration of the UE's stay on the PSCell served by the second SN.

2. The method according to claim 1, further comprising: The UE receives information indicating a secondary cell group (SCG) failure, wherein the information includes at least one of the following: information of the SN where the radio link failure occurred, information of the source SN during the last SN change process, and the type of SCG radio link failure.

3. The method according to claim 2, further comprising: Send a fourth message to the second SN reporting the SCG failure, wherein the fourth message includes at least one of the following: SCG failure information, an identifier assigned to the UE by the MN, an identifier assigned to the UE by the SN, information of the source SN to which the SN changed, information of the SN where the SCG radio link failure occurred, and mobility information.

4. The method according to claim 1, wherein, The first message also includes SN movement information related to the change of the SN.

5. The method according to claim 1, further comprising: Receive a fourth information list about the PSCell of the User Equipment (UE) from the second SN; A fourth message is sent to the second master node, the fourth message including a third information list about the PSCell of the user equipment (UE).

6. The method according to claim 5, wherein, The fourth information list and the third information list include at least one of the cell identifier of the PSCell and the duration of the user equipment (UE) connection to the cell.

7. The method according to claim 5, wherein, Sending the fourth message to the second master node includes sending the fourth message to the second master node via AMF.

8. A method for a second auxiliary node (SN) in a wireless communication system, the method comprising: The primary node MN receives a second message requesting the addition of the second SN based on a first message that triggers a change in the first SN, wherein the first message is sent by the first SN to the MN and includes a first information list about the primary and secondary cells PSCells served by the first SN for the user equipment UE. Receive a third message from the MN requesting the release of the second SN; and Send an acknowledgment message to the MN for the third message. The acknowledgment message includes a second information list about the PSCell served by the second SN for the UE. The second information list includes the cell identifier of the PSCell served by the second SN and the duration of the UE's stay on the PSCell served by the second SN.

9. The method according to claim 8, wherein, The UE sends information indicating a failure of the secondary cell group (SCG) to the MN, wherein the information includes at least one of the following: information of the SN where the radio link failure occurred, information of the source SN during the last SN change process, and the type of SCG radio link failure.

10. The method of claim 9, further comprising: The MN receives a fourth message reporting the SCG failure, wherein the fourth message includes at least one of the following: SCG failure information, an identifier assigned to the UE by the MN, an identifier assigned to the UE by the SN, information of the source SN of the SN change, information of the SN where the SCG radio link failure occurred, and mobility information.

11. The method according to claim 8, wherein, The first message also includes SN movement information related to the change of the SN.

12. The method according to claim 8, further comprising: Send a fourth information list about the PSCell of the User Equipment (UE) to the MN; The fourth message is sent by the MN to the second master node, and the fourth message includes a third information list about the PSCell of the user equipment (UE).

13. The method according to claim 12, wherein, The fourth information list and the third information list include at least one of the cell identifier of the PSCell and the duration of the user equipment (UE) connection to the cell.

14. The method according to claim 13, wherein, The fourth message is sent by the MN to the second master node via AMF.

15. A method for a first auxiliary node SN in a wireless communication system, the method comprising: Send a first message to the master node MN to trigger a change in the first SN. The first message includes a first information list about the primary and secondary cells PSCells served by the first SN for the user equipment UE. as well as Receive an acknowledgment message from the MN in response to the first message. Specifically, the second message requesting the addition of a second SN is sent by the MN to the second SN based on the first message. Specifically, the third message requesting the release of the second SN is sent by the MN to the second SN, and The confirmation message for the third message is sent by the second SN to the MN. The confirmation message for the third message includes a second information list about the UE's PSCell served by the second SN. The second information list includes the cell identifier of the PSCell served by the second SN and the duration of the UE's stay on the PSCell served by the second SN.

16. The method according to claim 15, wherein, The UE sends information indicating a failure of the secondary cell group (SCG) to the MN, wherein the information includes at least one of the following: information of the SN where the radio link failure occurred, information of the source SN during the last SN change process, and the type of SCG radio link failure.

17. The method according to claim 16, wherein, The fourth message reporting the SCG failure is sent by the MN to the second SN, wherein the fourth message includes at least one of the following: SCG failure information, an identifier assigned to the UE by the MN, an identifier assigned to the UE by the SN, information of the source SN of the SN change, information of the SN where the SCG radio link failure occurred, and mobility information.

18. The method according to claim 15, wherein, The first message also includes SN movement information related to the change of the SN.

19. The method according to claim 15, wherein, The fourth information list regarding the PSCell of the User Equipment (UE) is sent by the second SN to the MN, and The fourth message is sent by the MN to the second master node, and the fourth message includes a third information list about the PSCell of the user equipment (UE).

20. The method according to claim 19, wherein, The fourth information list and the third information list include at least one of the cell identifier of the PSCell and the duration of the user equipment (UE) connection to the cell.

21. The method according to claim 19, wherein, The fourth message is sent by the MN to the second master node via AMF.

22. A master node MN in a wireless communication system, the MN comprising: transceiver; and A processor, coupled to the transceiver, is configured to control: Receive a first message that triggers a change in the first secondary node SN, the first message including a first information list of primary and secondary cells PSCells served by the first SN for the user equipment UE; Based on the first message, a second message requesting the second SN to be added to the second SN is sent; Send a third message to the second SN requesting the release of the second SN; as well as The UE receives an acknowledgment message for the third message from the second SN. The acknowledgment message includes a second information list about the PSCell served by the second SN. The second information list includes the cell identifier of the PSCell served by the second SN and the duration of the UE's stay on the PSCell served by the second SN.

23. The MN according to claim 22, wherein, The processor is configured to control: The UE receives information indicating a secondary cell group (SCG) failure, wherein the information includes at least one of the following: information of the SN where the radio link failure occurred, information of the source SN during the last SN change process, and the type of SCG radio link failure.

24. The MN according to claim 23, wherein, The processor is configured to control: Send a fourth message to the second SN reporting the SCG failure, wherein the fourth message includes at least one of the following: SCG failure information, an identifier assigned to the UE by the MN, an identifier assigned to the UE by the SN, information of the source SN to which the SN changed, information of the SN where the SCG radio link failure occurred, and mobility information.

25. The MN according to claim 22, wherein, The first message also includes SN movement information related to the change of the SN.

26. The MN according to claim 22, wherein, The processor is configured to control: Receive a fourth information list about the PSCell of the User Equipment (UE) from the second SN; A fourth message is sent to the second master node, the fourth message including a third information list about the PSCell of the user equipment (UE).

27. The MN according to claim 26, wherein, The fourth and third information lists include at least one of the cell identifier of the PSCell and the duration of the user equipment (UE) connection to the cell.

28. The MN according to claim 26, wherein, Sending the fourth message to the second master node includes sending the fourth message to the second master node via AMF.

29. A second auxiliary node SN in a wireless communication system, comprising: transceiver; and A processor, coupled to the transceiver, is configured to perform the method according to any one of claims 8-14.

30. A first auxiliary node SN in a wireless communication system, comprising: transceiver; and A processor, coupled to the transceiver, is configured to perform the method according to any one of claims 15-21.

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