PSCell's modified LTM configuration

Abstract

The network node performs at least the following operations: acts as the SN of the UE, the UE and MN are in the DC, and the SN is associated with the SCG; receives information relating to the LTM configuration of the UE; provides the UE with information for performing a change from the source PSCell to the target PSCell; transmits information relating to the change of the UE from the source PSCell to the target PSCell, wherein at least one option applies: (i) the information enables the MN to update at least a portion of the LTM configuration based on the SCG configuration of the target PSCell; (ii) the information enables the MN to transmit information relating to an instruction to remove at least a portion of the LTM configuration for the UE.

Description

Technical Field

[0001] The following disclosure relates to the field of communication technology, specifically to communication networks, and more particularly to wireless communication networks. This disclosure may, for example, relate to an apparatus and one or more network nodes that can be used for low-level triggered mobility (LTM) and dual connectivity in a communication network, particularly for obtaining the latest LTM configuration after a change in the PSCell. Background Technology

[0002] Modern communication technologies such as 5G systems support dual connectivity, such as Multiple Radio Dual Connectivity (MR-DC). Dual connectivity allows a UE to be configured to utilize resources provided by two different nodes connected to each other. One node acts as the primary node (MN), and the other acts as the secondary node (SN). MN and SN are connected via a network interface, and at least MN is connected to the core network.

[0003] Recently, low-layer (L1 / L2) triggered mobility (LTM) has been introduced. LTM is a cell handover process triggered by the network, for example via MAC CE and based on, for example, Layer 1 (L1) measurements. In addition to the well-known and used Layer 3 (L3) mobility, LTM provides another mobility mechanism.

[0004] User equipment (UE) can be configured to support both LTM and L3 mobility simultaneously. However, in dual-connectivity scenarios, UEs may use outdated configurations. For example, this could occur in L3 mobility scenarios involving a PSCell within a secondary cell group (SCG) associated with the SN. Using outdated configurations is detrimental as it can lead to radio link failures (RLFs). It is desirable to at least partially mitigate or even overcome this problem. Summary of the Invention

[0005] Examples and embodiments can at least partially mitigate or even overcome this problem.

[0006] Based on the first example, the following is disclosed: A method executed by a user equipment, the method comprising: - It is in dual connectivity with the primary node MN and the secondary node SN, where SN is associated with the secondary cell group SCG; - In conjunction with the change from the source PSCell to the target PSCell, where the source PSCell is the primary cell of the SCG, perform at least one of the following: (i) Remove at least a portion of the low-level trigger mobility LTM configuration, wherein the at least a portion of the LTM configuration is associated with SCG; (ii) Update at least a portion of the LTM configuration based on the SCG configuration for the target PSCell, wherein the at least a portion of the LTM configuration is related to the SCG.

[0007] A method executed by a network node, the method comprising: - Acts as the primary node MN of a user equipment, which is in dual connectivity with both MN and secondary node SN, wherein SN is associated with the secondary cell group SCG; and - Transmits information for configuring the user equipment to perform the following operations in conjunction with changes to the source PSCell, where the source PSCell is the SCG's primary cell: (i) Remove at least a portion of the low-level trigger mobility LTM configuration, wherein the at least a portion of the LTM configuration is associated with SCG; (ii) Update at least a portion of the LTM configuration, which is related to the SCG.

[0008] Based on the second example, the following is disclosed: A method executed by a user equipment, the method comprising: - It is in dual connectivity with the primary node MN and the secondary node SN, where SN is associated with the secondary cell group SCG; - Receive information related to the low-level triggered mobility LTM configuration for user equipment; - Stores information related to LTM configuration for user equipment; - Perform the change from the source PSCell to the target PSCell, including informing the SN that the change has been completed; and - Receive information in response to instructing the SN that the change has been completed, wherein at least one of option (i) or option (ii) applies: Option (i): The information includes at least a portion of an updated LTM configuration based on an SCG configuration for a target PSCell, and the instructions, when executed by at least one processor, cause the user equipment to store the at least a portion of the updated LTM configuration; Option (ii): This information relates to an instruction to remove at least a portion of the LTM configuration for the user equipment, and these instructions, when executed by at least one processor, cause the user equipment to remove stored information related to the LTM configuration for the user equipment.

[0009] A method executed by a network node, the method comprising: - Acts as the primary node MN of a user equipment, which is in dual connectivity with both MN and secondary node SN, where SN is associated with the secondary cell group SCG; - Transmit information related to the low-level triggered mobility LTM configuration for the user equipment; - Transmit information related to the LTM configuration for user equipment to the SN; - Receive information from the SN related to changes in the user equipment from the source PSCell to the target PSCell; and - Execute at least one of option (i) or option (ii): Option (i): - Update at least a portion of the LTM configuration based on the SCG configuration for the target PSCell, wherein the SCG configuration for the target PSCell is included in the received information relating to changes in the user equipment from the source PSCell to the target PSCell; and - Transmit information to the user equipment, including at least a portion of the updated LTM configuration; Option (ii): Transmit to the user equipment information related to instructions for removing at least a portion of the LTM configuration for the user equipment.

[0010] A method executed by a network node, the method comprising: - Acts as a secondary node SN for a user equipment, which is in dual connectivity with the primary node MN and SN, wherein the SN is associated with the secondary cell group SCG; - Receive information from the MN related to the low-level triggered mobility LTM configuration for the user equipment; - Provide the user equipment with information for performing changes from the source PSCell to the target PSCell; - Transmit information to the MN related to changes in the user equipment from the source PSCell to the target PSCell, wherein at least one of option (i) or option (ii) applies: Option (i): - This information enables the MN to update at least a portion of the LTM configuration based on the SCG configuration for the target PSCCell included in the information provided related to the change of the user equipment from the source PSCCell to the target PSCCell; Option (ii): This information enables the MN to transmit information to the user equipment related to instructions for removing at least a portion of the LTM configuration for the user equipment.

[0011] Based on the third example, the following is disclosed: A method executed by a user equipment, the method comprising: - It is in dual connectivity with the primary node MN and the secondary node SN, where SN is associated with the secondary cell group SCG; - Receive information related to the low-level triggered mobility LTM configuration for user equipment; - Stores information related to LTM configuration for user equipment; - Receive information indicating a change from the source PSCell to the target PSCell, wherein at least one of option (i) or option (ii) applies: Option (i): The information indicating the change from the source PSCell to the target PSCell includes at least a portion of the updated LTM configuration based on the SCG configuration for the target PSCell; and the method further includes storing the at least a portion of the updated LTM configuration; Option (ii): The information indicating the change from the source PSCell to the target PSCell is related to the indication of removing at least a portion of the LTM configuration for the user equipment; and the method further includes removing stored information related to the LTM configuration for the user equipment; The method also includes: - Perform changes from the source PSCell to the target PSCell.

[0012] A method executed by a network node, the method comprising: - Acts as the primary node MN of a user equipment, which is in dual connectivity with both MN and secondary node SN, where SN is associated with the secondary cell group SCG; - Transmit information related to the low-level triggered mobility LTM configuration for the user equipment; - Transmit information related to the LTM configuration for user equipment to the SN; - Receive information from the SN related to upcoming changes to the user equipment from the source PSCell to the target PSCell; and - Execute at least one of option (i) or option (ii): Option (i): - Update at least a portion of the LTM configuration based on the SCG configuration for the target PSCell, wherein the SCG configuration for the target PSCell is included in the received information relating to the impending change of the user equipment from the source PSCell to the target PSCell; and - Transmit information to the user equipment indicating a change from the source PSCell to the target PSCell, including at least a portion of the updated LTM configuration; Option (ii): - Transmit information related to instructions for removing at least a portion of the LTM configuration for the user equipment to the user equipment.

[0013] A method executed by a network node, the method comprising: - Acts as a secondary node SN for a user equipment, which is in dual connectivity with the primary node MN and SN, wherein the SN is associated with the secondary cell group SCG; - Receive information from the MN related to the LTM configuration for the user equipment; and - Provide the MN with information related to the impending change of the user equipment from the source PSCell to the target PSCell, wherein at least one of option (i) or option (ii) applies: Option (i): - This information enables the MN to update at least a portion of the LTM configuration based on the SCG configuration for the target PSCell, which is included in the provided information relating to the impending change of the user equipment from the source PSCell to the target PSCell; Option (ii): This information enables the MN to transmit information to the user equipment related to an instruction to remove at least a portion of the LTM configuration for the user equipment.

[0014] Any disclosure relating to any example aspect herein should be understood as also disclosing any subject matter under the corresponding example aspect, such as apparatus, methods, computer programs, and computer-readable media. For example, any paragraph describing at least one processor and at least one memory including instructions, wherein the at least one memory and the instructions are configured to cooperate with the at least one processor to cause a user device or network node to perform at least one step, should be understood as simultaneously disclosing that step itself as a method step. Conversely, any paragraph describing a method or method step should be understood as simultaneously disclosing at least one processor and at least one memory including instructions, wherein the at least one memory and the instructions are configured to cooperate with the at least one processor to cause a user device or network node to perform at least the method or method step. Disclosure of a method or method step should also be considered as disclosure of components for performing and / or causing the performance of the corresponding method or method step. Similarly, disclosure of components for performing and / or causing the performance of a method or method step should also be considered as disclosure of the method or method step itself.

[0015] Specifically, an apparatus (e.g., a user equipment or a network node) is disclosed, configured to implement, execute, and / or control a method according to any of the foregoing example aspects, or including corresponding components for implementing and / or controlling the method. According to another example aspect, an apparatus (e.g., a user equipment or network node) is disclosed, comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to at least execute the method according to any one aspect.

[0016] The user equipment and / or network node in either aspect may include components for performing the specified methods or steps.

[0017] The apparatus disclosed in either aspect may include only (i.e. constitute) the disclosed components, such as parts, processors, or memory, or may also include one or more additional components.

[0018] These components can be implemented in hardware and / or software. For example, these components may include at least one processor for executing processor instructions to perform the desired function, at least one memory for storing these instructions, or both. Alternatively, these components may include, for example, circuitry designed or configured to perform the desired function, such as circuitry implemented in a chipset or chip (e.g., an integrated circuit). Typically, these components may include, for example, one or more processing components or processors.

[0019] As used in this application, the term "circuit" may refer to one, more, or all of the following: (a) Hardware circuit implementation only (e.g., implementation in analog and / or digital circuits); and (b) A combination of hardware circuitry and software, for example (where applicable): (i) A combination of analog and / or digital (multiple) hardware circuits and software / firmware; and (ii) Any part of a hardware processor that works in conjunction with software (including (multiple) digital signal processors), software, and (multiple) memories to enable a device such as a mobile phone or server to perform various functions; and (c) (Multiple) hardware circuits and / or (multiple) processors, such as (multiple) microprocessors or a portion thereof, which require software (e.g. firmware) to operate, but may be absent when operation does not require the software.

[0020] This definition of "circuit" applies to all uses of the term in this application, including its use in any claim. As another example, as used herein, the term "circuit" also covers only hardware circuitry or processors (or processors), a portion of hardware circuitry or processors, and implementations of their (or their) accompanying software and / or firmware. The term "circuit" also covers, for example, baseband integrated circuits or processor integrated circuits used in mobile devices, or similar integrated circuits in servers, cellular network devices, or other computing or networking devices, where applicable to specific claim elements. Any apparatus mentioned herein may include a circuit.

[0021] A network node can be a network entity in a communication network, such as a gNB, RAN node, base station, or part thereof. Network nodes can be logically and / or physically distributed.

[0022] A user equipment (UE) can be a device that enables a user to access network services. For example, a user equipment can be a mobile phone, smartphone, tablet, laptop, television, or Internet of Things (IoT) device. The interface between the UE and the network can be a radio interface.

[0023] In addition, a computer program product is disclosed that, when executed by a processor of a device (e.g., a user device or a network node), causes the device to perform a method according to any example aspect.

[0024] In addition, a computer program is disclosed that, when executed by a processor, causes one or more devices (e.g., user equipment or network node) to perform and / or control actions according to any of the example aspects of the method.

[0025] Additionally, a computer-readable storage medium (e.g., a tangible and / or non-transitory computer-readable storage medium) is disclosed, which includes at least one of the disclosed computer program product or computer program.

[0026] In addition, a system is disclosed. The system may include at least one of the following: one or more user equipments and one or more network nodes, such as a network node acting as the MN of the UE and a network node acting as the SN of the UE.

[0027] The following sections will describe example features and example implementations of all aspects in more detail.

[0028] Dual connectivity enables UEs with multiple Rx / Tx capabilities to be configured to utilize resources provided by two different nodes connected to each other. One node acts as the primary node (MN), and the other acts as the secondary node (SN). The MN and SN can be connected via a network interface, and at least the MN can be connected to the core network. An example of dual connectivity is multiple radio dual connectivity (MR-DC), where dual connectivity exists between an E-UTRA node and an NR node, or between two NR nodes.

[0029] Therefore, the UE can be in dual connectivity with both the MN and the SN. Accordingly, there exists a network node that acts as the MN of the UE in dual connectivity, and there exists a network node that acts as the SN of the UE.

[0030] Network nodes can be divided into Distributed Units (DUs) and Centralized Units (CUs). A CU can be understood as a logical node that includes functions such as user data transmission, mobility control, radio access network sharing, positioning, and session management (e.g., gNB functions), but excludes those functions specifically allocated to a DU. A DU can be understood as a logical node that includes a subset of functions (e.g., gNB functions), the operation of which can be controlled by a CU. A gNB can consist of gNB-CU-CPs, multiple gNB-CU-UPs, and multiple gNB-DUs, and can provide multiple cells.

[0031] The master node can be a radio access node. Specifically, the master node can be a radio access node that provides access to the control plane of the core network. For example, the master node can be a master eNB (e.g., in EN-DC), a master ng-eNB (e.g., in NGEN-DC), or a master gNB (e.g., in NR-DC and NE-DC).

[0032] An MN can be associated with a group of one or more serving cells. This group of one or more serving cells may include a special cell (SpCell, here PCell) and optionally one or more SCells. This group is called the primary cell group (MCG).

[0033] The term SpCell can be used to refer to the primary cell of a primary cell group or a secondary cell group.

[0034] The SpCell of an MCG is the primary cell PCell. The PCell can be the MCG cell in which the UE performs the initial connection establishment procedure or initiates the connection re-establishment procedure.

[0035] Secondary nodes can also be radio access nodes. Secondary nodes may or may not have a control plane connection to the core network and can provide additional resources to the UE. For example, a secondary node can be an en-gNB (e.g. in EN-DC), a secondary ng-eNB (e.g. in NE-DC), or a secondary gNB (e.g. in NR-DC or NGEN-DC).

[0036] An SN can be associated with a group of one or more serving cells. This group of one or more serving cells may include a special cell (SpCell, here PSCell) and optionally one or more SCells. This group is called a secondary cell group (SCG).

[0037] The SpCell of an SCG is the PSCell of the primary SCG cell. For example, the PSCell can be the SCG cell in which the UE performs random access, such as during a reconfiguration process with synchronization.

[0038] The UE can change the PSCell, that is, it can perform PSCell changes, such as changing from a source PSCell to a target PSCell. The UE can use mobility procedures to perform this change, such as L3 mobility, such as handover or conditional handover (CHO) and / or conditional PSCell addition or change (CPAC). This change may involve reconfiguration and / or synchronization, and can be triggered by the SN.

[0039] In various embodiments, the change from the source PSCell to the target PSCell includes: (For example, from MN or SN) receive information indicating a change from the source PSCell to the target PSCell; and In response to receiving the information indicating the change, the change is performed from the source PSCell to the target PSCell.

[0040] The information indicating a change from the source PSCell to the target PSCell can be an RRC reconfiguration message originating from the SN. Performing a change from the source PSCell to the target PSCell may include transmitting an RRC reconfiguration complete message.

[0041] For example, the SN can transmit an RRC reconfiguration message received by the UE. The SN can, for example, transmit the RRC reconfiguration message directly to the UE wirelessly, or it can send the message to the MN and have the MN forward it to the UE. The UE can, for example, perform random access (RA) to the target PSCell in response to the RRC reconfiguration message. This may involve transmitting a preamble to the target PSCell, receiving an RA response (RAR), and / or transmitting an RRC reconfiguration complete message to the target PSCell / SN.

[0042] This change can be made to a PSCell within the SN.

[0043] The SN can trigger this change in response to or based on information related to measurements of the UE. For example, this information may be or relate to a PSCell link quality indicator. This information may, for example, indicate PSCell link quality, and / or indicate that PSCell link quality is above or below a threshold, and / or is expected to rise above or fall below a threshold.

[0044] Additionally, the UE can be configured with an LTM configuration. The UE can be configured with an LTM configuration before, during, or at least after a PSCell change. Therefore, for example, while the UE has stored an LTM candidate configuration, the UE can also execute one or more, or any, L3 handover commands sent to the UE by the network.

[0045] LTM can be understood as a process where a network node (e.g., a gNB) receives multiple measurement reports (e.g., L1 measurement reports) from the UE and, based on these reports, changes the UE's serving cell via a cell handover command, for example, signaled via the MAC CE. The cell handover command may indicate an LTM candidate configuration previously prepared by the gNB and provided to the UE, for example, via RRC signaling. The UE can then switch to the target configuration according to the cell handover command. The LTM process can be used to reduce mobility latency.

[0046] LTM configuration can involve LTM for the primary cell group (MCG). For example, LTM configuration can be associated with at least one MCG. LTM configuration enables the UE to perform LTM cell change on an MCG cell (e.g., PCell).

[0047] The UE can receive information related to LTM configuration for the UE. Specifically, the UE can receive messages related to LTM configuration for the UE and can store this information. In this way, the UE can be configured for LTM. Specifically, this information can be information that the UE must use as at least part of its LTM configuration. The UE can receive this information from the MN, so the MN can transmit this information to the UE. Additionally or alternatively, the UE can be at least partially pre-configured with LTM.

[0048] An LTM configuration may include at least one of an LTM reference configuration and an LTM incremental configuration, or be composed of at least one of them. The reference configuration may be incomplete. For example, a reference configuration may be shared by a set of configured incomplete candidate configurations. A candidate configuration may be part of a message associated with a candidate cell (e.g., an RRC reconfiguration message), such as a configuration for LTM or subsequent CPAC. A candidate configuration may be a complete candidate configuration or an incremental configuration relative to the reference configuration. An incremental configuration may be combined with the reference configuration (e.g., overlaid on the reference configuration) to obtain a complete candidate configuration.

[0049] The LTM configuration can be a reference configuration or a target configuration used by the UE during cell changes (e.g., PCell changes). Alternatively or additionally, the LTM configuration can be a reference configuration or a target configuration used by the UE during PSCell changes.

[0050] The UE can perform an LTM change from the primary cell PCell of the Primary Cell Group (MCG) to another PCell. This can, for example, trigger the UE to replace or update its current UE configuration with another (e.g., a newly determined) complete candidate configuration after the change is completed. The complete candidate configuration used to replace the current UE configuration can be based on a stored candidate configuration or a reference configuration. It may be beneficial to ensure that the stored candidate configuration or reference configuration is up-to-date.

[0051] According to the first example aspect, the UE can combine the change from the source PSCell to the target PSCell (where the source PSCell is the main cell of the SCG) to perform at least one of the following: (i) Remove at least a portion of the LTM configuration that is associated with the SCG; (ii) Update at least a portion of the LTM configuration based on the SCG configuration for the target PSCell, wherein the at least a portion of the LTM configuration is related to the SCG.

[0052] At least a portion of the LTM configuration that is updated or removed may be or include at least one reference LTM configuration or candidate LTM configuration.

[0053] The UE can remove or update at least a portion of the LTM configuration in response to a change from the source PSCell to the target PSCell. For example, the UE can determine whether to remove or update at least a portion of the LTM configuration locally and / or without further information from the MN or SN. This allows the UE to avoid using outdated LTM configurations. It should be noted that the UE can perform actions that are not directly in response to messages from the MN or SN. Therefore, in various embodiments, the UE can autonomously decide whether to remove or update at least a portion of the LTM configuration.

[0054] In various embodiments, the UE can perform an LTM change from the primary cell PCell of the primary cell group (MCG) to another PCell, and after performing the LTM change to the other PCell, use at least a portion of the updated LTM configuration to connect to the target PSCell. The MCG may be associated with the MN.

[0055] The UE can be pre-configured to remove at least a portion of the LTM configuration or update at least a portion of the LTM configuration in conjunction with changes to the source PSCell (e.g., referencing the LTM configuration or candidate LTM configuration). For example, the standard specification may stipulate that the UE must remove or update at least a portion of the LTM configuration in conjunction with changes to the PSCell, for example, at least when other possible conditions are met.

[0056] Additionally or alternatively, the UE may receive information for configuring the UE to remove or update at least a portion of the LTM configuration in conjunction with a change in the source PSCell. For example, if the UE has received this information, the UE will remove or update at least a portion of the LTM configuration when the source PSCell changes. If the UE has not yet received this information, the UE will, for example, not remove or update at least a portion of the LTM configuration in conjunction with a change in the source PSCell, or will only perform this operation if certain other conditions are met.

[0057] The UE can receive this information, for example, from the MN that transmits the information. Furthermore, information used to configure the UE to remove or update at least a portion of the LTM configuration in conjunction with changes to the source PSCell can be included in the same message that also includes information related to the LTM configuration for the user equipment. For example, the UE can receive this information as part of the LTM configuration. This information can, for example, be included in the ltmConfig information element (IE) or transmitted in the same message as the ltmConfig IE.

[0058] The received information used to configure the UE to remove or update the LTM configuration in conjunction with changes to the source PSCell can originate from the MN. For example, this information can be received directly from the MN. Alternatively, this information can originate from the SN. This information can be, for example, a flag.

[0059] In various embodiments, the MN can transmit information for configuring the UE to incorporate changes to the source PSCell, which is the primary cell of the SCG: (i) Remove at least a portion of the LTM configuration that is associated with the SCG; (ii) Update at least a portion of the LTM configuration (e.g., refer to the LTM configuration or candidate LTM configuration), at least a portion of the LTM configuration being related to the SCG.

[0060] In the context of the first example, at least two scenarios can be distinguished based on how the UE updates or removes at least a portion of the LTM configuration.

[0061] First, the UE can be configured to update at least a portion of its LTM configuration by ensuring that the LTM configuration is consistent with the SCG configuration currently used by the UE. For example, after changing from a source PSCell to a target PSCell, the UE can update at least a portion of its LTM configuration using its current configuration for the target PSCell. As described above, the UE can be pre-configured to do this, or it can receive appropriate information to configure the UE to do so, for example, from the SN or MN.

[0062] Second, the UE can be configured to use information received, for example, from the SN or MN, to update at least a portion of the LTM configuration.

[0063] For example, changes from a source PSCell to a target PSCell can include: Receive information indicating the change from the source PSCell to the target PSCell, the information including the SCG configuration used for the target PSCell when updating at least a portion of the LTM configuration; and In response to receiving the information indicating the change, the change is performed from the source PSCell to the target PSCell.

[0064] The UE can use information including the SCG configuration for the target PSCell when updating at least a portion of the LTM configuration.

[0065] In various embodiments, the LTM configuration may include separate configurations for the SCG and MCG, such as separate reference configurations for the SCG and MCG.

[0066] In this scenario, the UE can update at least a portion of the LTM configuration by updating at least a separate reference configuration for the SCG. Updating at least a portion of the LTM configuration may include combining the separate reference configuration for the SCG (and / or MCG) with (e.g., a corresponding) LTM incremental configuration. In various embodiments, information for configuring the UE to update at least a portion of the LTM configuration in conjunction with changes to the source PSCell may configure the UE to update at least a portion of the LTM configuration by updating the separate reference configuration for the SCG, at least based on the SCG configuration for the target PSCell.

[0067] A separate reference configuration for the SCG can be provided to the UE by the SN, or alternatively by the MN.

[0068] The UE can be pre-configured to remove or update at least a portion of the LTM configuration and how to update that portion. Alternatively, the UE can receive information for configuring the UE to remove or update at least a portion of the LTM configuration and / or configuring how to update that portion. In various embodiments, the UE can be configured to perform both operations, such as removing or updating at least a portion of the LTM configuration based on the received information. In another embodiment, the UE is only configured to remove at least a portion of the LTM configuration without providing any update functionality. In other embodiments, the UE is only configured to update at least a portion of the LTM configuration (e.g., according to a single scheme) without providing any removal functionality.

[0069] The examples above involve UEs that proactively remove or update at least a portion of their LTM configuration. In these examples, the UE may remove or update at least a portion of its LTM configuration in conjunction with or in response to a PSCell change. In other words, a PSCell change can trigger the UE to remove or update at least a portion of its LTM configuration. This contrasts with methods where updates or removal are triggered, for example, by messages from the network.

[0070] Examples relating to the second and third example aspects will be described below. In these examples, the network node may play a more active role in attempting to prevent the UE from having an outdated configuration. However, it should be understood that all disclosures made with respect to the first embodiment, such as disclosures regarding the characteristics of LTM configuration, also apply to embodiments according to the second and third example aspects. One difference (or even the only difference in some embodiments) may be that, in embodiments according to the second and third example aspects, updates or removals at the UE may occur, for example, based on or in response to information received from the MN or SN.

[0071] According to the second example aspect, as described above, the MN transmits information related to the LTM configuration for the UE to the UE. The UE receives the information related to the LTM configuration for the UE and stores the information related to the LTM configuration for the UE.

[0072] In addition, the MN transmits information related to the LTM configuration for the UE to the SN, for example, by including this information in the SN modification request message.

[0073] Transmissions to the SN can occur during the transmission of information related to the LTM configuration for the UE to the UE. The SN receives the LTM configuration information related to the UE from the MN. For example, when the UE has an LTM configuration, it can notify the SN of that LTM configuration. The order of these operations (which generally also applies to the steps described herein) can be different; that is, the MN can transmit the information to the SN first and then to the UE, or even to both simultaneously.

[0074] In various embodiments, information related to the LTM configuration for the UE transmitted from the MN to the SN can trigger the SN to instruct the UE to change from the source PSCell to the target PSCell after a change occurs. This information may include or consist of indications that the UE has an LTM configuration and / or has a specific type of LTM configuration, such as an LTM configuration associated with the source PSCell. Additionally or alternatively, this information may include or consist of the entire LTM configuration for the UE itself.

[0075] Information related to the LTM configuration for the UE, transmitted from the MN to the SN, can be transmitted via the Xn interface and / or included in the SN modification request message. Alternatively, this information can be included in a message sent via the Xn interface that is not an SN modification request message. For example, this information can be transmitted in a new message (such as an SN notification message). This new message may not require acknowledgment.

[0076] The SN provides the UE with information for performing a change from a source PSCell (which may be a PSCell of an SCG and / or associated with an SCG) to a target PSCell. For example, the SN may provide this information in response to UE measurement-related information received from the UE (such as an L3 measurement report). The L3 measurement report may be based on an A3 event. Information sent from the SN to the UE may be or include an RRC reconfiguration message. This information may instruct the UE to perform a PSCell change, such as changing from a source PSCell to a target PSCell. The UE may respond to this information as described above, for example, by performing an RA procedure on the target PSCell. The RA procedure may include the UE transmitting an RA preamble to the target PSCell / SN, the UE receiving the RAR, and / or the UE transmitting an RRC reconfiguration completion message to the PSCell / SN.

[0077] The above steps apply accordingly to the UE. The UE performs a change from a source PSCell (which may be a PSCell of the SCG) to a target PSCell, including informing the SN that the change has been completed. The UE may perform this change in response to receiving information indicating that it is performing a change from the source PSCell to the target PSCell. Specifically, from the UE's perspective, the change from the source PSCell to the target PSCell may include: Receive information indicating a change from the source PSCell to the target PSCell (e.g., an RRC reconfiguration message); and In response to receiving the information indicating the change, the change is performed from the source PSCell to the target PSCell.

[0078] The UE can indicate to the SN that the change has been completed, for example, by transmitting an RRC reconfiguration complete message to the SN. Alternatively, the UE can indicate to the MN that the change has been completed.

[0079] In addition, the SN transmits information related to the change of the UE from the source PSCell to the target PSCell to the MN. The MN receives this information, that is, the MN receives information from the SN related to the change of the UE from the source PSCell to the target PSCell.

[0080] In various embodiments, information related to the change of the UE from the source PSCell to the target PSCell is included in the SN modification request message and / or sent via the Xn interface. Alternatively, this information may be included in a message sent via the Xn interface that is not an SN modification required message. For example, this information may be transmitted in a new message (such as an SN notification message). This new message may not require acknowledgment.

[0081] In various embodiments, information related to the change of the UE from the source PSCell to the target PSCell indicates to the MN that the LTM configuration needs to be updated or removed. The indication to the MN that the LTM configuration needs to be updated or removed may be or include flags.

[0082] Information related to a change in the UE's PSCell from a source PSCell to a target PSCell can, for example, indicate the UE's PSCell change to the MN. Similarly, this indication may be or include a flag. Additionally or alternatively, this indication can be made by setting a cause value accordingly, for example, a predetermined value. For example, the cause value could be the cause value for an SN modification request message.

[0083] For information transmitted by the SN and received by the MN that relates to the change of the UE from the source PSCell to the target PSCell, at least one of option (i) or option (ii) applies.

[0084] According to option (i), this information enables the MN to update at least a portion of the LTM configuration based on the SCG configuration for the target PSCell included in the provided information related to the change of the UE from the source PSCell to the target PSCell. For example, the SN can transmit at least a portion of the SCG configuration for the target PSCell to the MN.

[0085] Accordingly, the MN can update at least a portion of the LTM configuration based on the SCG configuration for the target PSCell, which is included in the received information related to the change of the UE from the source PSCell to the target PSCell. For example, the MN can replace at least some portions of the LTM configuration with the SCG configuration for the target PSCell. It should be noted that, unlike the embodiment according to the first exemplary aspect, in this embodiment, the LTM configuration is updated by the MN rather than the UE.

[0086] The MN can transmit to the UE information including at least a portion of the updated LTM configuration. For example, the MN can transmit that at least portion of the updated LTM configuration.

[0087] LTM configuration may include at least one of LTM reference configuration and LTM incremental configuration. In various embodiments, updating LTM configuration includes updating LTM reference configuration, and at least a portion of the updated LTM configuration included in the information transmitted to the UE is the updated LTM reference configuration.

[0088] As mentioned above, LTM configuration can involve LTM of the primary cell group (MCG) and / or can be a reference configuration or target configuration used by the UE during cell changes.

[0089] Still according to option (i), in response to indicating to the SN that the change has been completed, the UE may receive information including at least a portion of the updated LTM configuration based on the SCG configuration for the target PSCell. The UE may store this at least portion of the updated LTM configuration. Specifically, the UE may replace at least a portion of the LTM configuration based on this at least portion of the updated LTM configuration. For example, the UE may replace at least a portion of the previous LTM reference configuration with at least a portion of the updated LTM reference configuration.

[0090] Finally, the UE can perform an LTM change from the primary cell PCell of the primary cell group (MCG) associated with the MN to another PCell. After performing the LTM change to the other PCell, the UE can use the information related to updating the LTM configuration to connect to the target PSCell.

[0091] According to option (ii), the information transmitted by the SN and received by the MN related to the change of the UE from the source PSCell to the target PSCell enables the MN to transmit to the UE information related to an indication for removing at least a portion of the LTM configuration for the UE. Therefore, the MN can transmit to the UE information related to an indication for removing at least a portion of the LTM configuration for the UE.

[0092] Additionally (and optionally), the MN can, for example, remove at least a portion of the LTM configuration at the MN. Specifically, the MN can remove the LTM configuration for the UE based on information related to the change of the UE from the source PSCell to the target PSCell.

[0093] The information transmitted to the UE related to the removal instruction can be a command to the UE and can be embodied, for example, as a flag. In various embodiments, the UE can remove stored information related to the LTM configuration used by the UE. For example, the UE can perform the removal in response to or based on received information.

[0094] It can be seen that both options (i) and (ii) may be able to prevent the UE from using outdated LTM configurations.

[0095] The embodiments according to the third example aspect are similar to those according to the second example aspect. Therefore, all disclosures made with respect to the second example aspect will not be repeated, but should be understood as also being disclosed with respect to the third example aspect, and vice versa.

[0096] However, one difference between the embodiments according to the third example aspect and the embodiments according to the second example aspect may relate to when the SN transmits information to the MN related to the change of the UE from the source PSCell to the target PSCell. For example, in the embodiment according to the second example aspect, the SN may transmit information related to the change to the MN after the UE completes the change from the source PSCell to the target PSCell or in response to the completion of the change. In the embodiment according to the third example aspect, the SN may transmit information to the MN related to an impending change of the UE from the source PSCell to the target PSCell, such as when the change has not yet started, has not been indicated to the UE, or at least has not been completed. Thus, the MN may, for example, transmit information related to the updated configuration to the UE in an RRC reconfiguration message instructing the UE to perform a PSCell change.

[0097] As previously stated, in an embodiment according to the third example aspect, the UE is in dual connectivity with both the MN and the SN, and the SN is associated with the secondary cell group (SCG).

[0098] The MN transmits information related to the LTM configuration for the UE to the UE.

[0099] The UE receives and stores information related to the LTM configuration used by the UE.

[0100] The MN transmits information related to the LTM configuration for the UE to the SN.

[0101] The SN receives information from the MN related to the LTM configuration for the UE.

[0102] In various embodiments, information related to the LTM configuration for the UE transmitted from the MN to the SN can trigger the SN to provide the MN with information related to the impending change of the UE from the source PSCell to the target PSCell when it is preparing for the change. For example, preparing for the change may include determining that the link quality indicator is below a threshold.

[0103] The SN provides the MN with information related to upcoming changes to the UE from the source PSCell to the target PSCell, such as after the SN has begun preparing for the change or while the SN is preparing for the change.

[0104] In various embodiments, information related to an impending change in the UE from the source PSCell to the target PSCell can be used to indicate to the MN, using specified values ​​or fields (e.g., new reason values) in the SN modification request message, that the LTM configuration may need to be updated or removed due to the change in the UE's PSCell.

[0105] In addition, at least one of option (i) or option (ii) applies.

[0106] According to option (i), this information enables the MN to update at least a portion of the LTM configuration based on the SCG configuration for the target PSCell, which is included in the provided information related to the impending change of the UE from the source PSCell to the target PSCell.

[0107] The MN receives information from the SN related to an impending change in the UE's path from the source PSCell to the target PSCell. Furthermore, the MN updates at least a portion of the LTM configuration based on the SCG configuration for the target PSCell, which is included in the received information related to the impending change in the UE's path from the source PSCell to the target PSCell.

[0108] The MN transmits information to the UE indicating a change from the source PSCell to the target PSCell, including at least a portion of the updated LTM configuration.

[0109] The UE receives information indicating a change from the source PSCell to the target PSCell. The information indicating the change includes at least a portion of the updated LTM configuration based on the SCG configuration for the target PSCell. The UE stores this at least portion of the updated LTM configuration and performs the change from the source PSCell to the target PSCell.

[0110] According to option (ii), information transmitted from SN to MN related to an impending change in the UE from the source PSCell to the target PSCell enables MN to transmit information to the UE related to an indication to remove at least a portion of the LTM configuration for the UE.

[0111] The MN transmits information to the UE indicating a change from the source PSCell to the target PSCell, which is related to an indication of removing at least a portion of the LTM configuration used by the UE.

[0112] Furthermore, in various embodiments, the MN can remove the LTM configuration for the UE based on the SCG configuration for the target PSCell included in information related to the change of the UE from the source PSCell to the target PSCell, or based on specified values ​​or fields in the SN modification request message. Specifically, the MN can remove the LTM configuration for the UE by transmitting one or more instructions to the UE to remove the LTM configuration.

[0113] The UE receives information indicating a change from the source PSCell to the target PSCell, which is related to an indication to remove at least a portion of the LTM configuration used by the UE.

[0114] The UE removes stored information related to the LTM configuration used by the UE.

[0115] It should be understood that the descriptions in this section are for illustrative purposes only and not as limitations. Each of the steps described above may occur after another step (e.g., the previous step) or in response to another step. However, the steps may also be taken in a different order.

[0116] The term “information related to X” should be understood to cover at least the following situations: “the information includes X (part or all)” or “the information is X”.

[0117] Other features will become apparent from the following detailed description in conjunction with the accompanying drawings. However, it should be understood that the drawings are for illustrative purposes only and not for defining the scope of protection; for the scope of protection, reference should be made to the appended claims. It should also be understood that the drawings are not drawn to scale and are intended only to conceptually illustrate the structures and processes described herein. Attached Figure Description

[0118] The attached figures include: Figure 1 This is a block diagram illustrating an example of a dual-connectivity control plane architecture; Figure 2 This is a message sequence diagram illustrating an example of a message sequence that occurs when a UE experiences an SCG RLF due to outdated configuration; Figure 3 This is a flowchart illustrating an example embodiment of a method executable by a UE according to the first example aspect; Figure 4 This is a flowchart illustrating an example embodiment of a method that can be executed by a network node acting as an MN, according to the first example aspect; Figure 5 This is a message sequence diagram illustrating an example message sequence based on the first example aspect; Figure 6 This is a flowchart illustrating an example embodiment of a method executable by a UE according to the second example aspect; Figure 7 This is a flowchart illustrating an example embodiment of a method that can be performed by MN according to the second example aspect; Figure 8 This is a flowchart illustrating an example embodiment of a method executable by an SN according to the second example aspect; Figure 9 This is a message sequence diagram illustrating an example message sequence based on the second example aspect; Figure 10 This is a flowchart illustrating an example embodiment of a method executable by a UE according to a third example aspect; Figure 11 This is a flowchart illustrating an example embodiment of a method that can be performed by an MN according to the third example aspect; Figure 12 This is a flowchart illustrating an example embodiment of a method executable by an SN according to a third example aspect; Figure 13 This is a message sequence diagram illustrating an example message sequence based on the third example aspect; Figure 14 It is a schematic block diagram of an example of a UE or network node based on any example aspect. Detailed Implementation

[0119] The following description is intended to enhance understanding and should be understood as supplementing the description provided in the foregoing summary section of this specification, and should be read in conjunction with that description. The terminology used in some aspects may differ from, for example, the terminology used in the description above. However, those skilled in the art will understand that these terms refer to the same subject matter, for example, through more specific expressions.

[0120] Figure 1 This is a block diagram illustrating an example of a dual-connectivity control plane architecture 100. This control plane architecture is shown for a system including UE 1, a primary node (MN) 2, and a secondary node (SN) 3. UE 1 may be a multi-Rx / Tx UE 1 and may be configured to utilize resources provided by two different nodes. One node acts as MN 2, and the other acts as SN 3. UE 1 may connect to MN 2 via interface 101 (e.g., a radio interface, such as the Uu interface). Furthermore, UE 1 may connect to SN 3 via interface 104 (e.g., a radio interface, such as the Uu interface). MN 2 and SN 3 are connected via network interface 103 (e.g., the Xn interface). At least MN 2 is connected to the core network via interface 102.

[0121] MN 2 and SN 3, which participate in dual connectivity for a specific UE 1, can control its radio resources and can (e.g., primarily) be responsible for allocating radio resources for their cell.

[0122] An example of dual connectivity could be MR-DC. In MR-DC (or a similar technology), UE 1 can have a single RRC state based on MNRRC and a single control plane (C-plane) connection toward the core network. Each radio node (e.g., MN2 and SN 3) can have its own RRC entity. Each RRC entity can generate messages, such as RRC PDUs, to be sent to UE 1.

[0123] Messages generated by SN 3 can be transmitted to UE 1 via MN 2. MN 2 can always send the initial SN RRC configuration via MCG SRB (SRB1), but subsequent reconfigurations can be transmitted via either MN 2 or SN 3. In various embodiments, when transmitting messages from SN 3, MN 2 does not modify the UE configuration provided by SN 3.

[0124] Signaling radio bearers (SRBs) can be defined as radio bearers (RBs) used to transmit messages such as RRC messages and NAS messages, for example, only these messages are transmitted.

[0125] SRB1 allows direct message transmission (e.g., RRC PDU) between UE 1 and MN 2.

[0126] In various embodiments, UE 1 can be configured to establish an SRB (SRB3) with SN 3, enabling messages for SN 3 (e.g., RRC PDUs) to be sent directly between UE 1 and SN 3. This approach can be used, for example, when SN 3 is a gNB. SRB3 can be a direct SRB between SN 3 and UE 1. In various embodiments, messages for SN 3 (e.g., RRC PDUs) can only be directly transmitted to UE 1 for SN RRC reconfiguration messages that do not require any coordination with MN 2. In various embodiments, UE 1 can directly report measurements of mobility within SN 3 to SN 3. This approach can be used, for example, when SRB3 is configured.

[0127] The decision to establish an SRB3 can be made by SN 3, and SN 3 can provide SRB3 configuration using SN RRC messages. SRB3 can be established and released when a secondary node is added or changed. SRB3 can be reconfigured during secondary node modification.

[0128] SRB3 can be used to send SN RRC reconfiguration, SN RRC reconfiguration completion, SN measurement report, SN failure information (i.e., in the event of SCG RLC bearer failure), SN UE auxiliary information messages, and SN IABOtherInformation, for example, only in processes not involving MN 2. The SN RRC reconfiguration completion message can be mapped to the same SRB as the message that initiated the process. Regardless of whether the configuration is received directly from SN 3 or via MN 2, the SN measurement report message can be mapped to SRB3 (if configured). MN RRC messages may not be mapped to SRB3.

[0129] It can also support split SRBs. Split SRBs can allow the replication of messages (e.g., RRC PDUs) generated by MN 2 via the direct path and via the path via SN 3 (split SRB1). Additionally or alternatively, it can also allow the replication of messages (e.g., RRC PDUs) generated by SN 3 via both the MN 2 path and the SN 3 path.

[0130] Figure 2 This is a message sequence diagram illustrating an example of the message sequence when UE 1 experiences an SCG RLF due to outdated configuration.

[0131] As Figure 2 In the background, it should be noted that the LTM procedure has recently been proposed. LTM can be a procedure in which a network node receives multiple low-layer (e.g., L1) measurement reports from UE 1 and, based on these reports, changes the serving cell of UE 1, for example, via a cell handover command. The cell handover command can be signaled via the MAC CE. The cell handover command can indicate an LTM candidate configuration previously prepared by the network node and provided to UE 1, for example, via RRC signaling. UE 1 can then switch to the target configuration according to the cell handover command.

[0132] According to 3GPP TS 38.300 V18.0.0 (2023-12), in dual-connectivity scenarios, simultaneously changing the PCell and PSCell via LTM is not supported. To date, LTM with an MCG and an SCG is not supported, and the MCG LTM and SCG LTM execute independently. Therefore, the reference and candidate configurations for LTM to date can include either the MCG LTM configuration or the SCG LTM configuration, but not both simultaneously.

[0133] Furthermore, the RAN2#123bis meeting reached a consensus that UE 1 will only release the SCG configuration when performing MCG LTM if the network performs the corresponding configuration. Additionally, the RAN2#121 meeting reached a consensus that candidate incremental configurations will be overlaid on the reference configuration to form a complete candidate configuration, and this complete candidate configuration will be applied to replace the current UE configuration.

[0134] The above constraints also apply to SCG configurations. This means that, for example, when MCG LTM with SCG should be supported, the source SCG configuration may have to be part of a reference configuration or a candidate incremental configuration. The source configuration can be understood as the active cell group configuration used by the UE. The source SCG configuration can be understood as the active cell group configuration used by the UE for the secondary cell group.

[0135] In addition, it should be noted that L3 mobility can be configured in addition to LTM. For the coexistence of LTM and L3 mobility (such as traditional CHO / CPAC), the following two aspects can be considered: 1) Both LTM and CHO / CPAC can be configured simultaneously; 2) Share candidate configurations between CHO / CPAC and LTM: a. Allows LTM candidate configurations to be used in CHO / CPAC processes; b. Allow CHO / CPAC candidate configurations to be used in LTM processes.

[0136] In this context, the RAN2#123bis meeting assumed that L3 handover might occur when LTM is configured, evaluated, or used. To improve robustness, Rel-16 introduced CHO / CPAC, which can be similar to any other L3 mobility. To maintain consistency with traditional L3 handover, CHO / CPAC can also be configured for UE 1 when LTM candidate cells are configured, supporting simultaneous configuration of LTM and CHO / CPAC. According to RAN2, race conditions when LTM and CHO / CPAC coexist can be avoided through network configuration.

[0137] Xiaomi submitted a standardization proposal R2-2313167 entitled "RRC Opening Issues in LTM" to the 124th meeting of 3GPP TSG-RAN WG2, proposing that UE 1 does not voluntarily release the LTM configuration when performing CHO / CPAC, and that the RRC reconfiguration message applied for performing CHO / CPAC can reconfigure (establish or release) the LTM configuration.

[0138] However, these assumptions do not address the issue of the reference configuration potentially becoming obsolete, which will be discussed below. Figure 2 The examples in the document illustrate this.

[0139] Figure 2 Example message sequences involving UE 1, source MN-DU 2a and source MN-CU 2b (which constitute part of MN 2), and source SN 3 are shown.

[0140] As shown in step 201, UE 1 is configured with dual connectivity. This scenario illustrates an example of an SRB3 or split SRB1 configuration. However, similar issues may also apply to different configurations, such as UE 1 being configured with only SRB1.

[0141] In step 202, UE 1 is configured with MCG LTM.

[0142] As shown in 203, the MCG LTM configuration may include at least one of an LTM reference configuration and an LTM candidate incremental configuration, which may have a source PSCell 1 configuration. PSCell 1 may be associated with the SCG of source SN 3. UE 1 may be connected to PSCell 1, which is also referred to herein as the source PSCell.

[0143] In step 204, UE 1 can report the deteriorating PSCell link quality to source SN 3. For this purpose, UE 1 can use, for example, a measurement report, such as an L3 measurement report based on A3 events.

[0144] In steps 205 and 206, source SN 3 can configure a PSCell change. This PSCell change can be an intra-SN cell change and can involve UE 1 changing from the source PSCell (PSCell 1) to the target PSCell (PSCell 2). Specifically, in step 205, source SN 3 can prepare the target PSCell for UE 1. In step 206, source SN 3 can transmit a message (e.g., an RRC reconfiguration message) to UE 1. This message can instruct UE 1 to connect to the target PSCell.

[0145] Steps 207 to 209 illustrate an example RA procedure. For example, the RA procedure includes: UE 1 transmitting a (207) preamble to the target PSCell / source SN3; the target PSCell / source SN3 transmitting a (208) RAR to UE 1; and UE 1 transmitting a (209) RRC reconfiguration complete message to the target PSCell / source SN3.

[0146] Following these steps, the following issue may occur: After UE 1 applies the PSCell change, the SCG portion of the complete configuration (the old PSCell configuration) becomes invalid. As shown in 210, the LTM reference configuration or LTM candidate incremental configuration still has the PSCell1 configuration.

[0147] SN 3 is unaware of the LTM reference configuration and LTM candidate cell configuration. MN 2 is unaware of the PSCell change. This means that applying the LTM PCell change may result in an incorrect PSCell configuration because the reference configuration has not yet been updated.

[0148] If SRB1 is used (e.g., only SRB1 is used), MN 2 may also be unaware of the change. UE measurements of the SCG (see step 204) can still reach SN 3, for example, via MN 2 and / or via an RRC TRANSFER message within the RRC container IE in the UE report IE. The triggering of the PSCell change (see step 206) can be encapsulated as an RRC message in an RRC container and sent back to MN 2 via an RRC TRANSFER message, and then forwarded to UE 1 at MN 2. MN 2 may not be allowed or configured to read this message, so MN 2 will not be aware of the PSCell change.

[0149] An LTM cell change may then occur. In step 211, UE 1 may report L1 measurements to MN 2 (specifically MN-DU 2a). In step 212, MN-DU 2a may instruct UE 1 to perform a cell change, such as a PCell change.

[0150] After the PCell changes, UE 1 may be required (e.g., pre-configured) to re-determine the complete configuration. In step 213, UE 1 can form this complete configuration. Since UE 1 still has the PSCell 1 configuration, the PSCell 1 configuration will be used. For this reason, UE 1 will lose its current PSCell connection with PSCell 2, resulting in an SCG RLF.

[0151] One or more embodiments may allow updating the LTM configuration so that PSCell changes can coexist with the LTM configuration.

[0152] Figure 3 This is a flowchart illustrating an example embodiment of method 300 according to the first example aspect. The example method can be performed or implemented by UE 1 and includes: Step 301: The primary node MN 2 and the secondary node SN 3 are in dual connectivity, and SN 3 is associated with the secondary cell group SCG.

[0153] Step 302: In conjunction with the change from the source PSCell to the target PSCell (where the source PSCell is the SCG's primary cell), perform at least one of the following: (i) Remove at least a portion of the LTM configuration that is associated with the SCG; (ii) Update at least a portion of the LTM configuration based on the SCG configuration for the target PSCell, wherein the at least a portion of the LTM configuration is related to the SCG.

[0154] Figure 4This is a flowchart illustrating an example embodiment of method 400 according to the first example aspect. The example method can be performed or implemented by a network node acting as MN 2, and includes: Step 401: MN2 is used as UE 1 in dual connectivity with MN2 and SN3, and SN3 is associated with the secondary cell group SCG.

[0155] Step 402: Transmit information for configuring UE 1 to perform the following operations in conjunction with a change in the source PSCell, where the source PSCell is the primary cell of the SCG: Remove at least a portion of the LTM configuration that is associated with the SCG; Update at least a portion of the LTM configuration, which is related to the SCG.

[0156] Figure 5 This is a message sequence diagram illustrating an example of message sequence 500 according to the first example aspect.

[0157] Similar to Figure 2 , Figure 5 An example of a message sequence involving UE 1, source MN-DU 2a and source MN-CU 2b (both forming part of MN 2) and source SN 3 is shown.

[0158] Step 501 indicates that UE 1 is in dual connectivity with MN 2 (here, source MN-DU 2a and source MN-CU 2b are used as examples) and SN 3, and SN 3 is associated with the secondary cell group SCG. For example, this dual connectivity may include SRB3 and / or split SRB1. Therefore, the messages shown below can be transmitted using SRB3 and / or split SRB1 bearers.

[0159] In step 502, UE 1 is configured with an MCG LTM. This is an example of UE 1 receiving a message related to an LTM configuration for UE 1 that involves an MCG LTM. An LTM configuration involving an MCG LTM can also involve an SCG, such as an SCG configuration. Therefore, this LTM configuration can also affect the PSCell connection. The LTM configuration can be received and stored by UE 1, or alternatively, it can be pre-configured and thus stored on UE 1.

[0160] For example, step 502 also includes so-called "option 1a" or "option 1b". In various embodiments, UE 1 and / or the network only supports one of these options. In other embodiments, UE 1 and / or the network may support both options so that which option is used can be determined based on the specific circumstances.

[0161] According to option 1a, UE 1 is instructed to update the reference configuration with the new SCG configuration when or after a PSCell change occurs. The new SCG configuration may refer to an SCG configuration subsequently received, for example, for a PSCell change, after a PSCell change, or during a PSCell change, and may relate to the target PSCell. This is an example of UE 1 receiving information for configuring UE 1 to update at least a portion of its LTM configuration in conjunction with a change in the source PSCell, the information configuring UE 1 to update at least a portion of its LTM configuration by updating a separate reference configuration for the SCG based at least on the SCG configuration for the target PSCell.

[0162] According to option 1b, a separate reference configuration for SCG is indicated to UE 1, and this separate reference configuration is the source SCG configuration. The network can also instruct UE 1 to update the SCG reference configuration by reconfiguring the PSCell. For example, the reference configuration can be maintained in a separate container and updated to be consistent with the source SCG configuration. This is an example of UE 1 receiving information for configuring UE 1 to update at least a portion of its LTM configuration in conjunction with changes to the source PSCell, which configures UE 1 to update at least a portion of its LTM configuration by at least making the LTM configuration consistent with the SCG configuration currently used by UE 1.

[0163] In this example, options 1a and 1b are part of step 502, that is, part of the process by which UE 1 is configured with MCG LTM. However, in other embodiments, options 1a and 1b may occur independently of step 502, and / or before or after step 502.

[0164] Options 1a and 1b are examples of UE 1 receiving information for configuring UE 1 to update at least a portion of its LTM configuration in conjunction with changes to the source PSCell. In other embodiments, options 1a and / or 1b may be at least partially pre-configured.

[0165] Step 503 shows UE 1 transmitting a measurement report to source SN 3. For example, this measurement report is an L3 measurement report based on the A3 event.

[0166] Step 504 shows that source SN 3 prepares the target PSCell for UE 1. For example, a measurement report can enable source SN 3 to determine that a PSCell change should be performed.

[0167] In step 505, source SN 3 transmits an RRC reconfiguration message indicating a change in PSCell to UE 1. This is an example of UE 1 receiving information indicating a change from the source PSCell to the target PSCell. This information can be sent via MN 2 (e.g., by SN 3), or it can be sent by MN 2 itself.

[0168] In response to receiving information indicating the change, UE 1 can perform a change from the source PSCell to the target PSCell. For example, in step 506, UE 1 can send a preamble to the target PSCell / source SN 3. Subsequently, UE 1 can receive a RAR in step 507 and transmit an RRC reconfiguration complete message in step 508. However, this RA procedure is only an example, and other RA procedures can also be used.

[0169] In step 509, UE 1 updates the reference configuration. Step 509 is an example of the following operation: UE 1, in conjunction with the change from the source PSCell to the target PSCell, updates at least a portion of the LTM configuration based on the SCG configuration for the target PSCell, wherein the source PSCell is the primary cell of the SCG, and the at least a portion of the LTM configuration is related to the SCG.

[0170] In option 1a scenario, UE 1 may have already received the target PSCell configuration, for example, in the RRC reconfiguration message of step 505. UE 1 can use the new SCG configuration to update the reference configuration.

[0171] In Option 1b scenario, UE 1 can use PSCell reconfiguration. For example, a reference configuration can be maintained in a separate container, and this reference configuration can be updated to be consistent with the source SCG configuration. This is an example of UE 1 updating at least a portion of its LTM configuration by ensuring that the LTM configuration is consistent with the SCG configuration currently used by UE 1.

[0172] Therefore, it may be necessary to update the agreement reached at RAN2#121 to "apply candidate incremental configurations overlays to the reference configuration to form a complete candidate configuration." For example, this agreement could be updated to specify: - Apply candidate incremental configurations to both the MCG and SCG reference configurations to form a complete candidate configuration; and / or - Explicitly signal the SCG reference configuration to UE 1, or indicate to UE 1 via a flag that the SCG reference configuration is the source SCG configuration.

[0173] In step 510, UE 1 may transmit L1 measurements to source MN-DU 2a. In step 511, source MN-DU 2b may indicate a cell change to UE 1. UE 1 may then execute the cell change. This is an example of executing an LTM change from the primary cell PCell of the primary cell group MCG to another PCell.

[0174] After the PCell changes, UE 1 can use the updated configuration to connect to the target PSCell.

[0175] In general, an example of the process involving option 1a can be summarized as follows: When configuring LTM, UE 1 is instructed (e.g., by MN 2) that if a PSCell change occurs, the SCG portion of the reference LTM configuration or candidate LTM configuration should be updated using the source SCG configuration. Once the PSCell change occurs, UE 1 updates the SCG portion of the reference configuration or candidate LTM configuration.

[0176] An example of the process involving option 1b can be summarized as follows: When configuring LTM, a separate reference configuration for SCG and MCG configurations is indicated to UE 1. The network can indicate to UE 1 that the SCG reference configuration is the source SCG configuration. The network can also indicate to UE 1 that the SCG reference configuration is updated by UE 1 using PSCell reconfiguration, for example, the reference configuration can be maintained in a separate container and updated to be consistent with the source SCG configuration.

[0177] It should be understood that the order of steps in message sequence 500 can vary. For example, step 509 may occur before steps 506, 507, or 508. Similarly, option 1a (and / or option 1b) may be indicated before or after step 502 (e.g., after step 503 or after step 504). Furthermore, when a message is transmitted between two nodes, it may be relayed by a third node.

[0178] The above example illustrates that the SCG reference configuration can be provided to UE 1 by MN 2. Alternatively, the SCG reference configuration can be provided by SN 3. The SN configuration can be relayed to UE 1 via MN 2, or directly indicated to UE 1 by SN 3.

[0179] Combination Figure 5 The illustrated embodiments and combinations Figure 3 and Figure 4 The illustrated embodiments are as follows. Step 501 is an example of steps 301 and 401. Step 502 is an example of step 402. Steps 506 to 508 are examples of the change from the source PSCell to the target PSCell described in steps 302 and 402. Step 509 is an example of step 302.

[0180] Figure 6 This is a flowchart illustrating an example embodiment of method 600 according to the second example aspect. Method 600 can be performed, implemented, or controlled by UE 1 and includes the following steps: Step 601 includes dual connectivity with MN 2 and SN 3, with SN 3 associated with the secondary cell group SCG.

[0181] Step 602 includes, for example, receiving information related to the LTM configuration of UE 1 from MN 2.

[0182] Step 603 includes storing information related to the LTM configuration of UE 1.

[0183] Step 604 includes performing a change from the source PSCell to the target PSCell, including indicating to SN 3 that the change is complete.

[0184] Step 605 includes receiving information in response to indicating to SN 3 that the change is complete, wherein at least one of option (i) or option (ii) applies: Option (i): The information includes at least a portion of the updated LTM configuration based on the SCG configuration for the target PSCell, and the instruction causes UE 1 to store at least a portion of the updated LTM configuration when executed by at least one processor; Option (ii): The information relates to an instruction to remove at least a portion of the LTM configuration of UE 1, and the instruction, when executed by at least one processor, causes UE 1 to remove stored information relating to the LTM configuration of UE 1.

[0185] Figure 7 This is a flowchart illustrating an example embodiment of method 700 according to the second example aspect. Method 700 can be executed, implemented, or controlled by a network node and includes the following steps: Step 701 includes MN2 serving as UE 1 in dual connectivity with MN2 and SN3, SN3 being associated with the secondary cell group SCG.

[0186] Step 702 includes transmitting information related to the LTM configuration of UE 1 to UE 1.

[0187] Step 703 includes transmitting information related to the LTM configuration for UE 1 to SN 3.

[0188] Step 704 includes receiving information from SN 3 related to the change of UE 1 from source PSCell to target PSCell.

[0189] Step 705 includes performing at least one of option (i) or option (ii): Option (i): At least a portion of the LTM configuration is updated based on the SCG configuration for the target PSCell, and the SCG configuration for the target PSCell is included in the received information relating to the change of the UE 1 from the source PSCell to the target PSCell; and Transmit information including at least a portion of the updated LTM configuration to the UE 1; Option (ii): Transmit to the UE 1 information relating to an indication to remove at least a portion of the LTM configuration for the UE 1.

[0190] Figure 8 This is a flowchart illustrating an example embodiment of method 800 according to the second example aspect. Method 800 can be executed, implemented, or controlled by a network node and includes the following steps: Step 801 includes SN 3, which is used as UE 1 in dual connectivity with MN 2 and SN 3, and SN 3 is associated with the secondary cell group SCG.

[0191] Step 802 includes receiving information from MN 2 related to the LTM configuration of UE 1.

[0192] Step 803 includes providing UE 1 with information for performing a change from the source PSCell to the target PSCell.

[0193] Step 804 includes transmitting information to MN 2 related to the change of UE 1 from the source PSCell to the target PSCell, wherein at least one of option (i) or option (ii) applies: Option (i): This information enables MN 2 to update at least a portion of the LTM configuration based on the SCG configuration for the target PSCCell included in the information provided relating to the change of UE 1 from the source PSCell to the target PSCell; Option (ii): This information enables MN 2 to transmit to UE 1 information relating to an indication to remove at least a portion of the LTM configuration for UE 1.

[0194] Figure 9 This is a message sequence diagram illustrating an example of message sequence 900 according to the second example aspect.

[0195] Similar to Figure 5 , Figure 9An example of a message sequence involving UE 1, source MN-DU 2a and source MN-CU 2b (both forming part of MN 2) and source SN 3 is shown.

[0196] Step 901 indicates that UE 1 is in dual connectivity with MN 2 (here, source MN-DU 2a and source MN-CU 2b are used as examples) and SN 3, and SN 3 is associated with the secondary cell group SCG. For example, this dual connectivity may include SRB3 and / or split SRB1. Therefore, the messages shown below can be transmitted using SRB3 and / or split SRB1 bearers.

[0197] In step 902, UE 1 is configured with MCG LTM. This is an example of UE 1 receiving a message related to the LTM configuration for UE 1, which involves MCG LTM.

[0198] In step 903, source MN-CU 2b transmits an SN modification request message to source SN 3. This message can be transmitted via the Xn interface. This message notifies SN 3 of the configured LTM. This is an example of transmitting information related to the LTM configuration for UE 1 to SN 3.

[0199] In an alternative embodiment, information related to the LTM configuration for UE 1 transmitted from MN 2 to SN 3 is included in a message that is not an SN modification request message sent via the Xn interface.

[0200] In various embodiments, information related to the LTM configuration for UE 1 transmitted from MN 2 to SN 3 (e.g., SN modification request messages for notifying the configured LTM) can trigger SN 3 to instruct MN 2 to change UE 1 from the source PSCell to the target PSCell after the change occurs.

[0201] In step 904, source SN 3 transmits an SN modification request confirmation to source MN-CU 2b.

[0202] Step 905 shows UE 1 transmitting a measurement report to source SN 3. For example, this measurement report is an L3 measurement report based on the A3 event.

[0203] Step 906 shows that source SN 3 prepares the target PSCell for UE 1. For example, a measurement report may enable source SN 3 to determine that a PSCell change should be performed, for example because the source PSCell link quality has degraded below a threshold.

[0204] In step 907, source SN 3 transmits an RRC reconfiguration message to UE 1 indicating a change in PSCell. This is an example of UE 1 receiving information indicating a change from the source PSCell to the target PSCell. This information can be sent via MN 2 (e.g., by SN 3), or it can be sent by MN 2 itself.

[0205] In response to receiving information indicating the change, UE 1 can perform a change from the source PSCell to the target PSCell. For example, in step 908, UE 1 can send a preamble to the target PSCell / source SN 3. Subsequently, UE 1 can receive a RAR in step 909 and transmit an RRC reconfiguration complete message in step 910. However, this RA procedure is only an example, and other RA procedures can also be used.

[0206] In step 911, source SN 3 prepares to instruct PSCell to change and update or remove the LTM configuration.

[0207] Step 912 shows source SN 3 transmitting an SN modification request message to source MN-CU 2b. This message indicates to MN 2 that the PSCell has changed and also includes or relates to a new source SCG configuration. Step 912 is an example of step 804.

[0208] In step 913, the source MN-CU 913 sends an SN modification confirmation message to the source SN 3.

[0209] Before or after performing step 913, MN-CU 2b begins to execute at least one of option (i) or option (ii).

[0210] According to option (i), MN-CU 2b updates at least a portion of the LTM configuration based on the new SCG configuration of the target PSCell received in step 912.

[0211] In step 914, MN-CU 2b transmits an RRC reconfiguration message to UE 1 that includes a reference configuration update. This is an example of transmitting information to UE 1 that includes at least a portion of the updated LTM configuration.

[0212] UE 1 can store this reference configuration update. This can include replacing at least a portion of the previous configuration with new information based on the reference configuration update. It should be noted that in this example, MN 2 has updated its configuration and notified UE 1 accordingly. This is related to the combination of... Figure 5 The described embodiment of updating configuration by UE 1 forms a comparison.

[0213] In step 915, UE 1 transmits an RRC reconfiguration complete message to the source MN-CU 2b.

[0214] Steps 916 and 917 are similar to steps 510 and 511. After the PCell changes, UE 1 can use the updated configuration to connect to the target PSCell.

[0215] According to option (ii), MN-CU 2b is not required to update at least a portion of the LTM configuration based on the new SCG configuration of the target PSCell (therefore, source SN 3 may, but is not required to, send the new SCG configuration to source MN-CU in step 912), and / or is not required to transmit an RRC reconfiguration message including the reference configuration update to UE 1. Instead, MN-CU 2b transmits information to UE 1 related to an indication of removing at least a portion of the LTM configuration for UE 1. Therefore, UE 1 may not store the reference configuration update, but instead remove previously stored information related to the (e.g., obsolete) LTM configuration for UE 1.

[0216] In various embodiments, steps 903 and / or 912 may use an Xn message that is different from the SN modification request message. This is because this message is only used to notify SN 3 and does not require acknowledgment. This message may be a new message called an SN notification message.

[0217] in short, Figure 9 An example implementation may include the following process: After configuring the MCG LTM, the LTM configuration can be notified to SN 3. SN 3 can use this information as a trigger to indicate the PSCell change to MN 2 after a PSCell change occurs. This indication can be in the form of a flag. MN 2 updates the reference configuration after learning of the PSCell change and the new source SCG configuration.

[0218] Combination Figure 9 The illustrated embodiments and combinations Figures 6 to 8 The illustrated embodiments correspond as follows. Step 901 is an example of steps 601, 701, and 801. Step 902 is an example of steps 602 to 603 and step 702. Step 903 is an example of steps 703 and 802. Step 907 is an example of step 803. Step 912 is an example of steps 704 and 804. Step 914 is an example of steps 605 and 705.

[0219] Figure 10 This is a flowchart illustrating an example embodiment of method 1000 according to a third example aspect. This example method can be performed or implemented by UE 1 and includes, for example,: Step 1001: Dual connectivity with MN 2 and SN 3, with SN 3 associated with the secondary cell group SCG.

[0220] Step 1002: Receive information related to the LTM configuration of UE 1.

[0221] Step 1003: Store information related to the LTM configuration of UE 1.

[0222] Step 1004: Perform the change from the source PSCell to the target PSCell, including indicating to SN 3 that the change is complete.

[0223] Step 1005: In response to indicating to SN 3 that the change is complete, receive information where at least one of option (i) or option (ii) is applicable: Option (i): The information includes at least a portion of the updated LTM configuration based on the SCG configuration for the target PSCell, and the instruction causes UE 1 to store at least a portion of the updated LTM configuration when executed by at least one processor; Option (ii): The information relates to an instruction to remove at least a portion of the LTM configuration of UE 1, and the instruction, when executed by at least one processor, causes UE 1 to remove stored information relating to the LTM configuration of UE 1.

[0224] Figure 11 This is a flowchart illustrating an example embodiment of method 1100 according to a third example aspect. This example method can be executed or implemented by a network node and includes, for example, the following: Step 1101: MN2 is used as UE 1 in dual connectivity with MN2 and SN3, and SN3 is associated with the secondary cell group SCG.

[0225] Step 1102: Transmit information related to the LTM configuration of UE1 to UE1.

[0226] Step 1103: Transmit information related to the LTM configuration of UE 1 to SN 3.

[0227] Step 1104: Receive information from SN 3 related to the change of UE 1 from source PSCell to target PSCell; Step 1105: Execute at least one of option (i) or option (ii): Option (i): At least a portion of the LTM configuration is updated based on the SCG configuration for the target PSCell, and the SCG configuration for the target PSCell is included in the received information relating to the change of the UE 1 from the source PSCell to the target PSCell; and Transmit information including at least a portion of the updated LTM configuration to the UE 1; Option (ii): Transmit to the UE 1 information relating to an indication to remove at least a portion of the LTM configuration for the UE 1.

[0228] Figure 12 This is a flowchart illustrating an example embodiment of method 1200 according to a third example aspect. This example method can be executed or implemented by a network node and includes, for example, the following: Step 1201: SN3 is used as UE 1 in dual connectivity with MN 2 and SN 3, and SN 3 is associated with the secondary cell group SCG.

[0229] Step 1202: Receive information related to the LTM configuration of UE 1 from MN 2.

[0230] Step 1203: Provide UE 1 with information for performing changes from the source PSCell to the target PSCell.

[0231] Step 1204: Transmit to MN 2 information related to the change of UE 1 from source PSCell to target PSCell, wherein at least one of option (i) or option (ii) applies: Option (i): This information enables MN 2 to update at least a portion of the LTM configuration based on the SCG configuration for the target PSCCell included in the information provided relating to the change of UE 1 from the source PSCCell to the target PSCCell; Option (ii): This information enables MN 2 to transmit to UE 1 information relating to an indication of removing at least a portion of the LTM configuration for UE 1.

[0232] Figure 13 This is a message sequence diagram illustrating an example of message sequence 1300 according to the third example aspect.

[0233] and Figure 9 similar, Figure 13 Example message sequences involving UE 1, source MN-DU 2a and source MN-CU 2b (both of which constitute part of MN 2) and source SN 3 are shown.

[0234] It can be seen that, Figure 13 Many steps in Figure 9 The steps are similar. Therefore, Figure 9 The description of the intermediate steps, after necessary modifications, is applicable. Figure 13The corresponding steps in the process. Specifically, steps 901, 902, 903, 904, 905, 906, 908, 909, 911, 912, 913, 916 and 917 correspond to steps 1301, 1302, 1303, 1304, 1305, 1306, 1310, 1311, 1307, 1308, 1313, 1314 and 1315, respectively.

[0235] One difference between message sequence 900 and message sequence 1300 involves the order of steps. In message sequence 900, source SN 3 transmits an RRC reconfiguration message (step 907) and interacts with UE 1 to perform the RA procedure (steps 908 to 910) before instructing MN 2 on the PSCell change (steps 911, 912). In contrast, in message sequence 1300, source SN 3 instructs MN 2 on the impending PSCell change (steps 1307, 1308). Step 1308 is an example of SN 3 providing MN 2 with information related to the impending change of UE 1 from the source PSCell to the target PSCell. The RRC reconfiguration in step 1309 may include a reference configuration update. UE 1 may store (and thus, for example, apply) this reference configuration update.

[0236] Instructions to MN 2 that require reconfiguration (e.g., update or removal) and / or that such reconfiguration relates to a PSCell change (e.g., in step 1308) can be accordingly communicated to MN 2. These instructions enable MN 2 to transmit information instructing UE 1 to perform a PSCell change along with a reference configuration update (step 1309).

[0237] Information related to an impending change in UE 1 from the source PSCell to the target PSCell can be used to indicate to MN 2, via a specified value or field (e.g., a new reason value) in the SN modification request message, that the LTM configuration needs to be updated or removed. Alternatively, this information can indicate to MN 2 that the update or removal is necessary due to the change in UE 1's PSCell. The indication in step 1308 can be made to MN 2 by modifying the reason value in the SN modification request message.

[0238] For example, the above process can be used when using SRB1. In various embodiments, SRB3 is not used for dual connections.

[0239] Other embodiments need not include instructing MN 2 that a reconfiguration is required and / or that the reconfiguration is related to a PSCell change. For example, after configuring the MCG LTM, the LTM configuration can be notified to SN 3. SN 3 can use this information as a trigger to send a PSCell change configuration via MN 2 as needed (e.g., similar to SRB1 behavior). The instruction to MN 2 can also indicate that the message is for a PSCell change configuration, and therefore the reference configuration needs or may need to be updated. MN 2 can piggyback the updated reference configuration in the PSCell change configuration and can indicate this to UE 1.

[0240] Other embodiments that may be added to or used in place of the above embodiments are described below to mitigate or even overcome the problems of using outdated configurations.

[0241] For example, the network (e.g., a network node) can configure UE 1 to stop L1 measurement reporting once the PSCell changes, after the PSCell changes, when the PSCell changes, or in response to a PSCell change. The PSCell change can be notified to the MN-CU and / or MN-DU. This UE behavior can be pre-configured. For example, this UE behavior can be reflected by specifying the UE's behavior of stopping measurements in the specification. Alternatively, this UE behavior can be configured by the network node. Stopping L1 measurements (e.g., until further network notification) can mean that LTM does not exist (e.g., for a specific cell / cell group and / or until further notification). Therefore, even if UE 1 stores an outdated configuration, it may not need to apply that configuration due to an LTM cell change because no LTM cell change exists (e.g., for a specific cell / cell group or until further notification).

[0242] As another example, the network (e.g., a network node) can configure two LTM incremental configurations for UE 1. One incremental configuration can be used for single connectivity, and the other incremental configuration can (at least) include the source SCG (configuration). When performing an LTM PCell change, if the source SCG has changed after configuring the LTM configuration for UE 1, UE 1 can perform single connectivity (e.g., apply the single connectivity LTM incremental configuration). If the PSCell has not changed when performing the LTM PCell change, UE 1 can perform dual connectivity. UE 1 can also notify the network (e.g., a network node) of this choice (e.g., the applied configuration).

[0243] In another example, UE 1 can be configured to release part or all of the LTM configuration once the PSCell changes, after the PSCell changes, when the PSCell changes, or in response to a PSCell change. The PSCell change is notified to the source MN-CU and / or MN-DU.

[0244] Furthermore, in one example, SN 3 can be notified that MCG LTM has been configured. SN 3 can release the LTM configuration along with the PSCell configuration change (e.g., instructing UE 1 to release the LTM configuration), for example, via SRB3 in the same message or another message.

[0245] Furthermore, for changes in PSCell between SNs (e.g., not only does the PSCell change, but the associated SN also changes), MN 2 can update the reference configuration once received, after receiving, when receiving or in response to receiving the target SCG configuration from, for example, the target SN, and transmit, for example, the reference configuration or information related to the reference configuration to UE 1.

[0246] Finally, for inter-SN CPC, MN 2 can update the configuration once received, after receiving, when receiving or in response to receiving an indication from UE1, source SN 3 or target SN that UE1 has applied a new SCG configuration, and, for example, transmit the configuration or information related to the configuration to UE1.

[0247] Figure 14 A schematic block diagram of an example of a device 1400 (e.g., a UE or a network node) according to any example aspect is shown.

[0248] The device or network entity 1400 includes a processor 1401, a program memory 1402, a working memory or main memory 1403, a data memory, multiple communication interfaces 1404, and an optional user interface 1405.

[0249] The apparatus 1400 may, for example, be configured to perform and / or control a method according to any of the example aspects, or include corresponding components (at least one of 1401 to 1405) for performing and / or controlling the method. The apparatus 1400 may also constitute a UE 1 or a network node including at least one processor (1401) and at least one memory (1402) storing instructions that, when executed by the at least one processor, cause the UE 1 or network node (e.g., apparatus 1400) to at least perform and / or control a method according to any or all of the example aspects.

[0250] The processor 1401 may, for example, control at least one of the memories 1402 to 1403, one or more communication interfaces 1404 and / or an optional user interface 1405.

[0251] Processor 1401 may, for example, execute program code stored in program memory 1402. Program memory 1402 may, for example, represent a readable storage medium containing program code that, when executed by processor 1401, causes processor 1401 to perform a method according to any example aspect.

[0252] Processor 1401 (and any other processor mentioned herein) can be any suitable type of processor. Processor 1401 can include, but is not limited to: one or more microprocessors; one or more processors having one or more digital signal processors; one or more processors without digital signal processors; one or more application-specific computer chips; one or more field-programmable gate arrays (FPGAs); one or more controllers; one or more application-specific integrated circuits (ASICs); or one or more computers / servers. The associated architecture / hardware has been programmed to perform the described functions. Processor 1401 can be, for example, an application processor running an operating system.

[0253] Program memory 1402 may also be included in processor 1401. This memory may be fixedly connected to processor 1401, or at least partially removable from processor 1401, for example, in the form of a memory card or memory stick. Program memory 1402 may be, for example, non-volatile memory. For example, program memory 1402 may be any one of FLASH memory (or a portion thereof), ROM, PROM, EPROM, and EEPROM memory (or a portion thereof), or a hard disk (or a portion thereof), to name just a few. Program memory 1402 may include an operating system for processor 1401. Program memory 1402 may include firmware for device or network entity 1400.

[0254] Multiple communication interfaces 1404 enable device 1400 to communicate with other entities, such as one or more UEs or one or more network nodes. The multiple communication interfaces 1404 may include, for example, wireless interfaces (e.g., cellular radio communication interfaces and / or WLAN interfaces) and / or wired interfaces (e.g., IP-based interfaces), for example, for communicating with entities via the Internet. The multiple communication interfaces enable device 1400 to communicate with other entities, such as one or more entities included in a mobile communication network.

[0255] User interface 1405 is optional and may include a display for showing information to the user and / or an input device (such as a keyboard, keypad, touchpad, or mouse) for receiving information from the user.

[0256] Some or all of the components of device 1400 may be connected via a bus, for example. Some or all of the components of device or network entity 1400 may be combined into one or more modules, for example.

[0257] The apparatus 1400 may further include at least one of the following: a receiver, for example for receiving information from a network node or a UE; a transmitter, for example for transmitting information to a network node or a UE; an update component, for example for updating at least a portion of the configuration; a removal component, for example for removing at least a portion of the configuration; a storage component, for example for storing information; a transceiver, for example for being in dual connectivity and / or performing PSCell changes and / or performing PCell changes; and a providing component, for example for providing master node functionality or slave node functionality.

[0258] In this specification, any connection shown in the described embodiments should be understood as an operational coupling of the components involved. Therefore, connections can be direct or indirect, involving any number or combination of intermediate elements, and the components may have only a functional relationship.

[0259] Furthermore, any methods, processes, and actions described or illustrated herein may be implemented using executable instructions in a general-purpose processor or a special-purpose processor and stored on a computer-readable storage medium (such as a disk, memory, etc.) for execution by that processor. The reference to "computer-readable storage medium" should be understood to encompass special-purpose circuitry such as FPGAs, ASICs, signal processing devices, and other devices.

[0260] The expression “A and / or B” is considered to include any of the following three cases: (i) A; (ii) B; (iii) A and B. Furthermore, the article “a” should not be interpreted as “a”, meaning that using the expression “a component” does not exclude the presence of other components. The term “including” should be interpreted in an open sense, meaning that the object “including component A” can also include other components besides component A. Furthermore, the term “including” can also be interpreted as explicitly “consisting of”, meaning consisting only of the specified components.

[0261] The phrase “at least one of the following: ”, “at least one of ”, and similar wording (where the elements in the list are connected by “and” or “or”) means: at least any one element, at least any two or more elements, or at least all elements.

[0262] It should be understood that all embodiments shown are merely examples, and any feature shown for a particular example embodiment may be used alone with any aspect, or in combination with any feature shown for the same or another particular example embodiment, and / or in combination with any other feature not mentioned. Specifically, the example embodiments shown in this specification should also be understood to be disclosed in all possible combinations thereof, provided that they are technically reasonable and the example embodiments are not substitutes for each other. It should also be understood that any feature shown in example embodiments of a particular class (method / apparatus / computer program / system) may also be used in a corresponding manner in example embodiments of any other class. It should also be understood that the presence of a feature in an example embodiment shown does not necessarily mean that the feature is essential and cannot be omitted or replaced.

[0263] The statement "a feature includes at least one of the features listed subsequently" should not be construed as including all features listed subsequently or at least one of the multiple features listed subsequently. The listed features can be selected in any combination, or only one of the listed features can be selected. Specific combinations of all the features listed subsequently can also be considered. Furthermore, a single listed feature may exist in multiple forms.

[0264] The order of all the method steps described above is not mandatory, and other orders may be used. However, the specific order of the method steps shown by way of example in the accompanying drawings should be considered as one possible order of the method steps of the corresponding embodiments described in the corresponding drawings.

[0265] The subject matter has been described above with the aid of exemplary embodiments. It should be noted that other methods and variations, which will be apparent to those skilled in the art, may also be implemented without departing from the scope of the appended claims.

[0266] List of abbreviations: 3GPP Third Generation Partnership Program; 5G (Fifth Generation) CHO condition switching Adding or changing CPAC condition PSCell CU Centralized Unit DU Distributed Unit gNB Next Generation Node B IE Information Elements L1 Floor 1 L2 Floor 2 L3 Floor 3 LTM triggers mobility at lower levels; L1 / L2 triggers mobility. MAC Media Access Control MCG Main Cell Group MN master node PCell main cell PSCell main SCG cell RAN (Radio Access Network) RLF radio link failure RRC Radio Resource Control Rx receiver SCG Auxiliary Community Group SN auxiliary node SRB signaling radio bearer Tx transmitter UE User Equipment

Claims

1. A user equipment, comprising: At least one processor; as well as At least one memory storing instructions that, when executed by the at least one processor, cause the user equipment to perform at least the following: - It is in dual connectivity with the primary node MN and the secondary node SN, wherein the SN is associated with the secondary cell group SCG; - Receive information relating to the low-level triggered mobility LTM configuration for the user equipment; - Store the information relating to the LTM configuration used for the user equipment; - Perform a change from the source PSCell to the target PSCell, including instructing the SN that the change is complete; as well as - In response to indicating to the SN that the change is complete, receive information, wherein at least one of option (i) or option (ii) applies: Option (i): The information includes at least a portion of an updated LTM configuration, the at least a portion of which is based on an SCG configuration for the target PSCell, and the instruction, when executed by the at least one processor, causes the user equipment to store the at least a portion of the updated LTM configuration; Option (ii): The information relates to an instruction to remove at least a portion of the LTM configuration for the user equipment, and the instruction, when executed by the at least one processor, causes the user equipment to remove stored information relating to the LTM configuration for the user equipment.

2. The user equipment of claim 1, wherein the instructions, when executed by the at least one processor, cause the user equipment to perform at least the following: Perform an LTM change from the primary cell PCell of the primary cell group (MCG) to another PCell; and After the LTM change is performed to the other PCell, the information associated with the updated LTM configuration is used for the connection to the target PSCell.

3. The user equipment according to any one of the preceding claims, wherein the change from the source PSCell to the target PSCell includes: - Receive information indicating a change from the source PSCell to the target PSCell; as well as - In response to receiving the information indicating the change, perform the change from the source PSCell to the target PSCell.

4. The user equipment according to any one of the preceding claims, wherein the updated LTM configuration includes an updated LTM reference configuration, and the at least portion of the updated LTM configuration included in the received information is the updated LTM reference configuration.

5. A network node, comprising: At least one processor; as well as At least one memory storing instructions that, when executed by the at least one processor, cause the network node to execute at least the following: - Acts as the primary node MN of the user equipment, wherein the user equipment is in dual connectivity with the MN and the secondary node SN, and the SN is associated with the secondary cell group SCG; - Transmit information related to the low-level triggered mobility LTM configuration for the user equipment; - Transmit information related to the LTM configuration for the user equipment to the SN; - Receive information from the SN related to the change of the user equipment from the source PSCell to the target PSCell; as well as - Execute at least one of option (i) or option (ii): Option (i): - Update at least a portion of the LTM configuration based on the SCG configuration for the target PSCell, wherein the SCG configuration for the target PSCell is included in the received information relating to the change of the user equipment from the source PSCell to the target PSCell; and - Transmit information including at least a portion of the updated LTM configuration to the user equipment; Option (ii): Information relating to the instruction to remove at least a portion of the LTM configuration for the user equipment is transmitted to the user equipment.

6. The network node of claim 5, wherein the updated LTM configuration includes an updated LTM reference configuration, and includes at least a portion of the updated LTM configuration in the information transmitted to the user equipment as the updated LTM reference configuration.

7. A network node, comprising: At least one processor; as well as At least one memory storing instructions that, when executed by the at least one processor, cause the network node to execute at least the following: - Acts as a secondary node SN with a user equipment, the user equipment being in dual connectivity with the primary node MN and the secondary node SN, the SN being associated with a secondary cell group SCG; - Receive information from the MN relating to the low-level triggered mobility LTM configuration for the user equipment; - Provide the user equipment with information for performing a change from the source PSCell to the target PSCell; - Transmit to the MN information relating to the change of the user equipment from the source PSCell to the target PSCell, wherein at least one of option (i) or option (ii) applies: Option (i): - The information enables the MN to update at least a portion of the LTM configuration based on the SCG configuration for the target PSCell, the SCG configuration for the target PSCell being included in the information provided in relation to the change of the user equipment from the source PSCell to the target PSCell; Option (ii): The information enables the MN to transmit information to the user equipment relating to an instruction to remove at least a portion of the LTM configuration for the user equipment.

8. The network node according to any one of claims 5 to 7, wherein the information associated with the LTM configuration for the user equipment and transmitted from the MN to the SN triggers: once the change occurs, the SN instructs the MN of the change of the user equipment from the source PSCell to the target PSCell.

9. The network node according to any one of claims 5 to 8, wherein the information related to the LTM configuration for the user equipment and transmitted from the MN to the SN is included in the SN modification request message.

10. The network node according to any one of claims 5 to 8, wherein the information related to the LTM configuration for the user equipment and transmitted from the MN to the SN is included in a message sent via the Xn interface, the message being not an SN modification request message.

11. The subject matter of any one of claims 5 to 10, wherein the information relating to the change of the user equipment from the source PSCell to the target PSCell indicates to the MN that the LTM configuration needs to be updated or removed.

12. The network node according to any one of claims 5 to 11, wherein the information related to the change of the user equipment from the source PSCell to the target PSCell indicates a change in the PSCell of the user equipment.

13. The network node according to any one of claims 5 to 12, wherein the information related to the change of the user equipment from the source PSCell to the target PSCell is included in the SN modification request message sent via the Xn interface.

14. The network node according to any one of claims 5 to 12, wherein the information related to the change of the user equipment from the source PSCell to the target PSCell is included in a message sent via the Xn interface, the message being not an SN modification request message.

15. The network node according to any one of claims 5 to 14, wherein the MN removes the LTM configuration for the user equipment based on the information related to the change of the user equipment from the source PSCell to the target PSCell.

16. The subject matter according to any one of the preceding claims, wherein the LTM configuration includes at least one of an LTM reference configuration and an LTM incremental configuration.

17. The subject matter according to any one of the preceding claims, wherein the LTM configuration is associated with the LTM of the primary cell group (MCG).

18. The subject matter according to any one of the preceding claims, wherein the LTM configuration is a reference configuration or target configuration to be used by the user equipment in a cell change.

19. A method performed by a user equipment, the method comprising: - It is in dual connectivity with the primary node MN and the secondary node SN, wherein the SN is associated with the secondary cell group SCG; - Receive information relating to the low-level triggered mobility LTM configuration for the user equipment; - Store the information relating to the LTM configuration used for the user equipment; - Perform a change from the source PSCell to the target PSCell, including instructing the SN that the change is complete; as well as - In response to indicating to the SN that the change is complete, receive information, wherein at least one of option (i) or option (ii) applies: Option (i): The information includes at least a portion of an updated LTM configuration, the at least a portion of which is based on an SCG configuration for the target PSCell, and the instruction, when executed by the at least one processor, causes the user equipment to store the at least a portion of the updated LTM configuration; Option (ii): The information relates to an instruction to remove at least a portion of the LTM configuration for the user equipment, and the instruction, when executed by the at least one processor, causes the user equipment to remove stored information relating to the LTM configuration for the user equipment.

20. A method performed by a network node, the method comprising: - Acts as the primary node MN of the user equipment, wherein the user equipment is in dual connectivity with the MN and the secondary node SN, and the SN is associated with the secondary cell group SCG; - Transmit information related to the low-level triggered mobility LTM configuration for the user equipment; - Transmit information related to the LTM configuration for the user equipment to the SN; - Receive information from the SN related to the change of the user equipment from the source PSCell to the target PSCell; as well as - Execute at least one of option (i) or option (ii): Option (i): - Update at least a portion of the LTM configuration based on the SCG configuration for the target PSCell, wherein the SCG configuration for the target PSCell is included in the received information relating to the change of the user equipment from the source PSCell to the target PSCell; and - Transmit information including at least a portion of the updated LTM configuration to the user equipment; Option (ii): Information relating to the instruction to remove at least a portion of the LTM configuration for the user equipment is transmitted to the user equipment.

21. A method performed by a network node, the method comprising: - Acts as a secondary node SN for user equipment, wherein the user equipment is in dual connectivity with the primary node MN and the secondary node SN, and the SN is associated with the secondary cell group SCG; - Receive information from the MN relating to the low-level triggered mobility LTM configuration for the user equipment; - Provide the user equipment with information for performing a change from the source PSCell to the target PSCell; - Transmit to the MN information relating to the change of the user equipment from the source PSCell to the target PSCell, wherein at least one of option (i) or option (ii) applies: Option (i): - The information enables the MN to update at least a portion of the LTM configuration based on the SCG configuration for the target PSCell, the SCG configuration for the target PSCell being included in the information provided in relation to the change of the user equipment from the source PSCell to the target PSCell; Option (ii): The information enables the MN to transmit information to the user equipment relating to an instruction to remove at least a portion of the LTM configuration for the user equipment.

22. A computer program comprising instructions that, when executed by a device, cause the device to perform the method of any one of claims 19 to 21.

23. A computer-readable storage medium having a computer program as described in claim 22 stored thereon.

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