WO2025160913A1 - Cell switch implementation and configuration methods and apparatuses - Google Patents

Abstract

Embodiments of the present application provide cell switch implementation and configuration methods and apparatuses. The implementation method comprises: a terminal device receiving L1/L2-triggered mobility (LTM) configuration information sent by a network device; and the terminal device implementing an LTM cell switch, wherein the terminal device retains a configuration (attemptLTM-Switch) used for attempting an LTM switch.

Description

Method and device for executing and configuring cell change Technical Field

The embodiments of the present application relate to the field of communication technologies.

Background Art

Network-controlled mobility applies to connected devices and can be categorized into two types: cell-level mobility and beam-level mobility. Cell-level mobility requires explicit Radio Resource Control (RRC) signaling, i.e., RRC-triggered handovers.

The RRC-triggered handover mechanism requires the terminal device to at least reset the Media Access Control (MAC) entity and re-establish the Radio Link Control (RLC). RRC-managed handovers are supported with and without the Packet Data Convergence Protocol (PDCP) entity re-establishment.

For data radio bearers (DRBs) using RLC AM mode, PDCP can either re-establish with a security key update or initiate a data recovery procedure without a key update. For DRBs using RLC UM mode, PDCP can either re-establish with a security key update or remain unchanged without a key update. For signaling radio bearers (SRBs), PDCP can remain unchanged without a key update, discard stored PDCP PDUs/SDUs, or re-establish with a security key update.

Cell-level mobility also includes changing serving cells via Layer 1 (L1)/Layer 2 (L2) signaling. Figure 1 illustrates an example scenario for L1/L2-based inter-cell mobility. As shown in Figure 1, when a terminal device moves from one cell's coverage area to another, a serving cell change is required at some point.

Currently, serving cell changes are triggered by Layer 3 (L3) measurements and completed by RRC signaling, triggering reconfiguration with synchronization for PCell and PSCell changes, and the release of SCells when applicable. All cases involve a full L2 (and L1) reset, resulting in longer latency, greater overhead, and longer disruption than beam switching mobility.

The goal of L1/L2 mobility enhancement is to ensure that the serving cell change through L1/L2 signaling can reduce latency, overhead and interruption time. In order to reduce mobility delay, the mechanism and process of inter-cell mobility based on L1/L2 can include: configuration and maintenance of multiple candidate cells to allow rapid application of candidate cell configuration; Applicable scenarios include a dynamic switching mechanism between candidate serving cells (including special cells and secondary cells) based on L1/L2 signaling; L1 enhancement of inter-cell beam management, including L1 measurement and reporting, as well as beam indication; timing advance (TA) management; and CU-DU interface signaling to support L1/L2 mobility.

It should be noted that the above introduction to the technical background is merely intended to provide a clear and complete description of the technical solutions of this application and facilitate understanding by those skilled in the art. Simply because these solutions are described in the background technology section of this application, it should not be assumed that the above technical solutions are well known to those skilled in the art.

Summary of the Invention

The inventors discovered that currently network equipment can configure CHO candidate cells or LTM candidate cells for terminal devices to support conditional switching (CHO) or L1/L2 triggered mobility (LTM, L1/L2 Triggering Mobility) operations; however, when an LTM cell change (LTM cell switch) is performed, the configuration used to attempt the LTM change (attemptLTM-Switch) will be released or cleared, and the LTM candidate cells will no longer be able to be used for failure recovery. This makes it impossible for the terminal device to recover quickly in some cases, thereby causing greater service interruption.

To address at least one of the above problems, embodiments of the present application provide a method and apparatus for executing and configuring a cell change.

According to one aspect of an embodiment of the present application, a method for executing a cell change is provided, including:

The terminal device receives configuration information of Layer 1/Layer 2 Triggered Mobility (LTM) sent by the network device;

The terminal device performs an LTM cell change (LTM cell switch), wherein the terminal device retains a configuration for attempting an LTM change (attemptLTM-Switch).

According to another aspect of an embodiment of the present application, a device for executing a cell change is provided, including:

a receiving unit configured to receive configuration information of Layer 1/Layer 2 Triggered Mobility (LTM) sent by a network device;

A processing unit which performs an LTM cell change (LTM cell switch), wherein the terminal device retains a configuration for attempting an LTM change (attemptLTM-Switch).

According to another aspect of an embodiment of the present application, a method for configuring a cell change is provided, including:

The network device sends Layer 1/Layer 2 Triggered Mobility (LTM) configuration information to the terminal device;

The configuration for attempting LTM changes (attemptLTM-Switch) is included in the above-mentioned configuration information, or the configuration for attempting LTM changes (attemptLTM-Switch) is included in the first information of the above-mentioned configuration information, or the configuration for attempting LTM changes (attemptLTM-Switch) is included in the RRC reconfiguration message.

According to another aspect of an embodiment of the present application, a cell change configuration device is provided, including:

a sending unit, configured to send configuration information of Layer 1/Layer 2 Triggered Mobility (LTM) to a terminal device;

The configuration for attempting LTM change (attemptLTM-Switch) is included in the configuration information, or the configuration for attempting LTM change (attemptLTM-Switch) is included in the first information of the configuration information, or the configuration for attempting LTM change (attemptLTM-Switch) is included in the RRC reconfiguration message.

According to another aspect of an embodiment of the present application, a communication system is provided, including:

A network device that sends Layer 1/Layer 2 Triggered Mobility (LTM) configuration information to a terminal device;

A terminal device receives configuration information of Layer 1/Layer 2 Triggered Mobility (LTM) sent by the network device and performs an LTM cell change (LTM cell switch), wherein the terminal device retains a configuration for attempting the LTM change (attemptLTM-Switch).

One of the beneficial effects of the embodiments of the present application is that the terminal device performs an LTM cell change (LTM cell switch), in which the configuration for attempting the LTM change (attemptLTM-Switch) is retained. Therefore, after each LTM cell change is performed, the LTM candidate configuration can still be used for rapid recovery from failure, reducing service interruption caused by RRC reconstruction, thereby improving user experience.

With reference to the following description and accompanying drawings, specific embodiments of the present application are disclosed in detail, indicating the manner in which the principles of the present application can be employed. It should be understood that the embodiments of the present application are not limited in scope. Within the spirit and scope of the appended claims, the embodiments of the present application include many variations, modifications and equivalents.

Features described and/or illustrated with respect to one embodiment may be used in the same or similar manner in one or more other embodiments, combined with features in other embodiments, or substituted for features in other embodiments.

It should be emphasized that the term "include/comprising" when used herein refers to the presence of features, integers, steps or components, but does not exclude the presence or addition of one or more other features, integers, steps or components.

BRIEF DESCRIPTION OF THE DRAWINGS

The elements and features described in one figure or one embodiment of the present application can be combined with the elements and features shown in one or more other figures or embodiments. In addition, in the accompanying drawings, similar reference numerals represent corresponding parts in several figures and can be used to indicate corresponding parts used in more than one embodiment.

FIG1 is an example diagram of a scenario of inter-cell mobility based on L1/L2;

FIG2 is a schematic diagram of a communication system according to an embodiment of the present application;

FIG3 is a schematic diagram of the signaling process of LTM;

FIG4 is a schematic diagram of a failure recovery process;

FIG5 is a schematic diagram of a method for executing a cell change according to an embodiment of the present application;

FIG. 6 is an example diagram of the behavior of LTM on the UE side according to an embodiment of the present application.

FIG7 is a schematic diagram of a configuration method for cell change according to an embodiment of the present application;

FIG8 is a schematic diagram of an apparatus for executing a cell change according to an embodiment of the present application;

FIG9 is a schematic diagram of a configuration device for cell change according to an embodiment of the present application;

FIG10 is a schematic diagram of a terminal device according to an embodiment of the present application;

FIG11 is a schematic diagram of a network device according to an embodiment of the present application.

DETAILED DESCRIPTION

The above and other features of the present application will become apparent through the following description with reference to the accompanying drawings. In the description and the accompanying drawings, specific embodiments of the present application are disclosed in detail, which illustrate some embodiments in which the principles of the present application can be adopted. It should be understood that the present application is not limited to the described embodiments. On the contrary, the present application includes all modifications, variations and equivalents that fall within the scope of the appended claims.

In the embodiments of the present application, the terms "first", "second", etc. are used to distinguish different elements from the name, but do not indicate the spatial arrangement or temporal order of these elements, and these elements should not be limited by these terms. The term "and/or" includes any one and all combinations of one or more of the associated listed terms. The terms "comprising", "including", "having", etc. refer to the presence of the stated features, elements, components or components, but do not exclude the presence or addition of one or more other features, elements, components or components.

In the embodiments of this application, the singular forms "a," "the," etc. include plural forms and should be broadly understood to mean "a" or "a type" rather than being limited to "one." Furthermore, the term "said" should be understood to include both singular and plural forms, unless the context clearly indicates otherwise. Furthermore, the term "according to" should be understood to mean "at least in part based on...", and the term "based on" should be understood to mean "at least in part based on...", unless the context clearly indicates otherwise.

In the embodiments of the present application, the term "communication network" or "wireless communication network" may refer to a network that complies with any of the following communication standards, such as Long Term Evolution (LTE), enhanced Long Term Evolution (LTE-A, LTE-Advanced), Wideband Code Division Multiple Access (WCDMA), High-Speed Packet Access (HSPA), etc.

Furthermore, communication between devices in the communication system may be carried out according to communication protocols of any stage, such as but not limited to the following communication protocols: 1G (generation), 2G, 2.5G, 2.75G, 3G, 4G, 4.5G and 5G, New Radio (NR), future 6G, etc., and/or other communication protocols currently known or to be developed in the future.

In the embodiments of the present application, the term "network device" refers to, for example, a device in a communication system that connects a terminal device to the communication network and provides services for the terminal device. Network devices may include, but are not limited to, base stations (BS), access points (AP), transmission reception points (TRP), broadcast transmitters, mobile management entities (MME), gateways, servers, radio network controllers (RNC), base station controllers (BSC), and the like.

Among them, base stations may include but are not limited to: NodeB (NodeB or NB), evolved NodeB (eNodeB or eNB) and 5G base station (gNB), IAB host, etc., and may also include remote radio heads (RRH, Remote Radio Head), remote radio units (RRU, Remote Radio Unit), relays or low-power nodes (such as femeto, pico, etc.). The term "base station" can include some or all of their functions. Each base station can provide communication coverage for a specific geographical area. The term "cell" can refer to a base station and/or its coverage area, depending on the context in which the term is used.

In the embodiments of the present application, the term "user equipment" (UE) or "terminal equipment" (TE) refers to a device that accesses a communication network through a network device and receives network services. A terminal device can be fixed or mobile and may also be referred to as a mobile station (MS), a terminal, a subscriber station (SS), an access terminal (AT), a station, etc.

Among them, terminal devices may include but are not limited to the following devices: cellular phones, personal digital assistants (PDAs), wireless modems, wireless communication devices, handheld devices, machine-type communication devices, laptop computers, cordless phones, smart phones, smart watches, digital cameras, etc.

For another example, in scenarios such as the Internet of Things (IoT), the terminal device can also be a machine or device for monitoring or measurement, including but not limited to: machine type communication (MTC) terminal, vehicle-mounted communication terminal, device-to-device (D2D) terminal, machine-to-machine (M2M) terminal, and so on.

In addition, the term "network side" or "network device side" refers to one side of the network, which can be a base station or one or more network devices as described above. The term "user side" or "terminal side" or "terminal device side" refers to the user or terminal side, which can be a UE or one or more terminal devices as described above. Unless otherwise specified herein, "device" can refer to either network equipment or terminal equipment.

The following describes the scenarios of the embodiments of the present application through examples, but the present application is not limited thereto.

FIG2 is a schematic diagram of a communication system according to an embodiment of the present application, schematically illustrating a situation using a terminal device and a network device as an example. As shown in FIG2 , a communication system 100 may include a network device 101 and terminal devices 102 and 103. For simplicity, FIG2 illustrates only two terminal devices and one network device as an example, but the embodiments of the present application are not limited thereto.

In the embodiment of the present application, existing services or future services can be transmitted between the network device 101 and the terminal devices 102 and 103. For example, these services may include, but are not limited to, enhanced mobile broadband (eMBB), massive machine type communication (mMTC), and ultra-reliable and low-latency communication (URLLC), etc.

It is worth noting that FIG2 shows that both terminal devices 102 and 103 are within the coverage range of network device 101, but the present application is not limited thereto. Both terminal devices 102 and 103 may not be within the coverage range of network device 101, or one terminal device 102 may be within the coverage range of network device 101 while the other terminal device 103 is outside the coverage range of network device 101.

The terminal device can perform an LTM process, in which a network device (e.g., a gNB) receives an L1 measurement report from the terminal device. Based on the L1 measurement report, the network device can change the serving cell of the terminal device by issuing a cell switch command via the MAC CE.

For example, after an LTM cell handover, the terminal device does not update its security keys; subsequent LTM is supported. LTM supports intra-gNB-DU mobility and inter-gNB-DU mobility within a gNB-CU. LTM supports both intra-frequency and inter-frequency mobility, including movement to an inter-frequency cell other than the current serving cell. LTM can support the following scenarios: PCell changes in non-Carrying-Aided Cells (CA) and non-DC scenarios; PCell changes in CA scenarios; and in dual connectivity scenarios, MCG PCell changes and SCG PSCell changes not involving a mobile node (i.e., intra-SN PSCell changes).

Figure 3 is a schematic diagram of the LTM signaling process. As shown in Figure 3, the LTM process may include:

Step 1: The UE sends a MeasurementReport message to the gNB. The gNB decides to configure LTM and initiates candidate cell configuration.

Step 2: The gNB sends an RRCReconfiguration message to the UE, including the LTM candidate cell configuration of one or more candidate cells.

Step 3: The UE stores the LTM candidate cell configuration and sends an RRCReconfigurationComplete message to the gNB.

Step 4: Before receiving the cell change command, the UE performs DL synchronization of the candidate cell;

When UE-based TA measurement is configured, the UE obtains the TA value of the candidate cell through measurement. Otherwise, before receiving a cell change command, if the network requests that the UE perform early TA acquisition of the candidate cell, this can be accomplished by triggering a CFRA from the PDCCH order of the source cell and then sending a preamble from the UE to the indicated candidate cell. To minimize data interruption in the source cell caused by the CFRA to the candidate cell, the UE does not receive a random access response from the network to obtain the TA value. The TA value of the candidate cell is indicated in the cell handover command. The UE does not maintain a TA timer for the candidate cell and relies on the network to ensure TA validity.

Step 5: The UE performs L1 measurements on the configured candidate cells and sends an L1 measurement report to the gNB. L1 measurements should be performed whenever RRC reconfiguration (step 2) applies.

Step 6: The gNB decides to perform a cell change to the target cell and sends a MAC CE indicating a cell change with the candidate configuration index of the target cell. The UE switches to the target cell and applies the configuration indicated by the candidate configuration index.

Step 7: If the UE does not have a valid TA for the target cell, the UE performs a random access procedure to the target cell. If the LTM cell change command MAC CE includes CFRA information, the UE performs CFRA.

Step 8: The UE completes the LTM cell change procedure by sending an RRCReconfigurationComplete message to the target cell. If the UE has already performed a random access procedure in step 7, the UE considers the LTM cell change to be successfully completed when the random access procedure is successfully completed. For RACH-less LTM, the UE considers the LTM cell change to be successfully completed when it determines that the network has successfully received its first UL data. The UE determines the successful reception of its first UL data by receiving a newly transmitted PDCCH addressed by the UE's C-RNTI in the target cell after the first UL data is scheduled. This PDCCH carries a DL assignment or an UL grant for the same HARQ process as the first UL data.

Subsequent LTM is performed by repeating the early synchronization, LTM cell change execution, and LTM cell change completion steps. After each LTM cell change is completed, the other LTM candidate cell configurations are not released. That is, using the LTM candidate cell configuration provided in step 2, steps 4-8 can be performed multiple times.

The above schematically illustrates LTM. The following describes recovery from handover failure and recovery from radio link failure.

For handover failure recovery, NR supports a timer-based Handover Failure (HOF) procedure. The RRC connection reestablishment procedure is used for handover failure recovery, except in certain CHO or DAPS handover scenarios:

-When DAPS handover fails, if the source link has not been released, the UE falls back to the source cell configuration, restores the connection with the source cell, and reports the DAPS handover failure through the source, without triggering RRC connection re-establishment;

- When the initial CHO execution attempt fails or the HO handover fails, the UE performs cell selection and if the selected cell is a CHO candidate and if the network has configured the UE to attempt CHO after handover/CHO failure, then the UE attempts CHO execution once, otherwise it performs re-establishment.

For radio link failure recovery, after RLF is declared, the UE:

- Maintain RRC_CONNECTED;

- In the case of a DAPS handover, for RLF in the source cell: all data transmission or reception over the source link is stopped and the source link is released, but the source RRC configuration is maintained; if a handover failure is subsequently detected in the target cell, the UE: selects a suitable cell and initiates RRC re-establishment; if no suitable cell is found within a certain period of time after declaring handover failure, it enters RRC_IDLE;

- In case of CHO, for RLF in the source cell: select a suitable cell and if the selected cell is a CHO candidate and if the network has configured CHO after RLF, the UE attempts CHO once, otherwise performs re-establishment; if no suitable cell is found within a certain time after declaring handover failure, enter RRC_IDLE;

- In case of LTM (L1/L2 Triggered Mobility), for RLF in the source cell: select a suitable cell and if the selected cell is an LTM candidate and if the network has configured LTM after RLF, the UE attempts LTM once, otherwise performs re-establishment; if no suitable cell is found within a certain period of time after declaring handover failure, enter RRC_IDLE;

- Otherwise, for RLF in the serving cell or in the target cell before releasing the source cell in case of DAPS handover: select a suitable cell and initiate RRC re-establishment; if no suitable cell is found within a certain period of time after declaring RLF, enter RRC_IDLE.

Figure 4 is a schematic diagram of failure recovery. As shown in Figure 4, when a radio link failure or handover failure occurs, the terminal device initiates the RRC connection reestablishment process, which involves first selecting a cell. If the selected cell is a CHO candidate cell, the terminal device attempts a CHO. Otherwise, the RRC connection reestablishment process continues, sending an RRC reestablishment request message.

Alternatively, when the UE selects a suitable NR cell, if the cell selection is triggered by detection of MCG RLF, MCG synchronization reconfiguration failure or mobility failure from NR, if attemptLTM-Switch is configured and if the selected cell is one of the LTM candidate cells in the LTM-Candidate IE in the VarLTM-Config associated with the MCG, the UE shall perform the LTM cell change procedure for the selected LTM candidate cell.

The UE will perform the above LTM cell change procedure according to the following defined behaviors:

Release/clear all current dedicated radio configurations associated with the cell group that triggered the LTM cell change procedure, except:

- logicalChannelIdentityExt and logicalChannelIdentity of the RLC bearer configured in RLC-BearerConfig and the associated RLC entities, their state variables, buffers and timers;

-UE variables VarLTM-Config, VarLTM-ServingCellNoResetID and VarLTM-ServingCellUE-MeasuredTA-ID;

- If the LTM cell change is triggered on the MCG,

--MCG C-RNTI;

--Master key associated AS security configuration;

--For each SRB/DRB using the master key in the current UE configuration:

- Save the associated PDCP and SDAP entities, their state variables, buffers and timers;

- Release all fields related to the SRB/DRB configuration except srb-Identity and drb-Identity.

According to the current RAN2 agreement, the UE keeps the LTM configuration as the result of the LTM recovery. Therefore, the UE should be able to use LTM candidate cells for failure recovery after LTM execution. However, according to the current mechanism, the attemptLTM-Switch is released or cleared when the LTM cell changes execution. This means that once LTM is executed, the LTM candidate cell can no longer be used for failure recovery as the UE does not meet the "attemptLTM-Switch configured" condition.

Therefore, according to the current mechanism, once LTM is executed, the LTM candidate cell will no longer be used for the above-mentioned failure recovery, which makes it impossible for the UE to recover quickly in some cases, thereby causing greater service interruption. The above schematically illustrates the relevant contents of the embodiment of the present application, and the present application is further explained below.

Embodiments of the first aspect

The embodiment of the present application provides a method for executing a cell switch. FIG5 is a schematic diagram of a method for executing a cell change according to an example embodiment, as shown in FIG5 , the method includes:

501, the terminal device receives configuration information of Layer 1/Layer 2 Triggered Mobility (LTM) sent by the network device;

502. The terminal device performs an LTM cell change (LTM cell switch), wherein the terminal device retains a configuration for attempting an LTM change (attemptLTM-Switch).

It is worth noting that FIG5 above is merely a schematic illustration of an embodiment of the present application, and the present application is not limited thereto. For example, the execution order of the various operations may be appropriately adjusted, and other operations may be added or some operations may be reduced. Those skilled in the art may make appropriate modifications based on the above description, and are not limited to the description of FIG5 above.

In some embodiments, the configuration and signaling process of LTM can refer to Figure 3. For example, IEs such as LTM-Config and/or LTM-Candidate can be used, and the details can be referred to related technologies.

In some embodiments, the terminal device retains the configuration for attempting LTM change (attemptLTM-Switch), including: the terminal device does not release or clear the configuration for attempting LTM change (attemptLTM-Switch); or, the terminal device releases or clears all current dedicated wireless configurations associated with the cell group or MCG where the LTM cell change (LTM cell switch) is triggered, at least except the configuration for attempting LTM change (attemptLTM-Switch).

For example, retaining the attemptLTM-Switch (the configuration/related variables) can be replaced with not releasing/clearing the attemptLTM-Switch (the configuration/related variables).

For another example, retaining attemptLTM-Switch (configuration/related variables), you can replace it with:

- Release/clear all current dedicated radio configurations associated with the cell group or MCG that triggered the LTM cell change procedure, except:

-attemptLTM-Switch (configuration/related variables);

- logicalChannelIdentityExt and logicalChannelIdentity of the RLC bearer configured in RLC-BearerConfig and the associated RLC entities, their state variables, buffers and timers;

-UE variables VarLTM-Config, VarLTM-ServingCellNoResetID and VarLTM-ServingCellUE-MeasuredTA-ID.

Table 1 illustrates an example of LTM cell change execution.

Table 1

In some embodiments, the configuration for attempting an LTM change (attemptLTM-Switch) is stored in a first UE variable. For example, the first UE variable is at least one of the following: an LTM configuration variable (VarLTM-Config), a first LTM serving cell variable (VarLTM-ServingCellNoResetID), or a second LTM serving cell variable (VarLTM-ServingCellUE-MeasuredTA-ID).

Table 2 illustrates an example in which attemptLTM-Switch is stored in VarLTM-Config.

Table 2

In some embodiments, the terminal device retains the configuration for attempting LTM change (attemptLTM-Switch), including: the terminal device releases or clears all current dedicated radio configurations associated with the cell group or MCG where the LTM cell switch is triggered, except for the first UE variable.

Table 3 illustrates an example of LTM cell switch execution, where attemptLTM-Switch is saved in the first UE variable.

Table 3

In some embodiments, the configuration for attempting LTM change (attemptLTM-Switch) is configured in the configuration information (LTM-Config) of LTM, and the terminal device stores the configuration for attempting LTM change (attemptLTM-Switch) or related variables in the first UE variable; and/or

If the configuration for attempting LTM changes (attemptLTM-Switch) is not configured in the LTM configuration information (LTM-Config), the terminal device removes (remove)/releases/clears the configuration for attempting LTM changes (attemptLTM-Switch) in the first UE variable.

Table 4 illustrates an example of LTM configuration and execution.

Table 4

In some embodiments, the configuration for attempting LTM change (attemptLTM-Switch) is configured in the configuration information (LTM-Config) of LTM and there is no configuration for attempting LTM change (attemptLTM-Switch) in the first UE variable, then the terminal device stores the configuration for attempting LTM change (attemptLTM-Switch) in the first UE variable; and/or

The configuration for attempting LTM changes (attemptLTM-Switch) is not configured in the configuration information (LTM-Config) of the LTM and the configuration for attempting LTM changes (attemptLTM-Switch) is present in the first UE variable, then the terminal device removes (remove)/releases/clears the configuration for attempting LTM changes (attemptLTM-Switch) in the first UE variable.

Table 5 illustrates another example of LTM configuration and execution.

Table 5

As can be seen from the above embodiment, attemptLTM-Switch is stored in the first UE variable. Because the first UE variable is not released or cleared during an LTM cell change, attemptLTM-Switch is preserved. This allows the LTM candidate configuration to be used for rapid recovery after each LTM cell change, minimizing service interruptions caused by RRC reestablishment and improving the user experience.

In some embodiments, the configuration for attempting the LTM change (attemptLTM-Switch) is saved in the first information of the second UE variable.

For example, the second UE variable is an LTM configuration variable (VarLTM-Config). For example, the first information is at least one of the following: a reference configuration (ReferenceConfiguration) and an LTM candidate configuration (LTM-Candidate).

In some embodiments, the terminal device retains a configuration for attempting LTM changes (attemptLTM-Switch), including: the LTM candidate configuration (LTM-Candidate) includes a configuration for attempting LTM changes (attemptLTM-Switch), then the terminal device adds the received configuration for attempting LTM changes (attemptLTM-Switch) to the first information of the second UE variable.

Table 6 shows an example of adding/modifying an LTM candidate configuration, using attemptLTM-Switch saved in LTM-Candidate as an example.

Table 6

Table 7 illustrates an example in which attemptLTM-Switch is stored in LTM-Candidate.

Table 7

As can be seen from the above embodiment, attemptLTM-Switch is included in the first information, and the first information is stored in the second UE variable. Because the second UE variable is not released/cleared when the LTM cell change is executed, attemptLTM-Switch can be saved. This way, after each LTM cell change is executed, the LTM candidate configuration can still be used for fast recovery in case of failure, reducing service interruption caused by RRC reestablishment and thus improving user experience.

In some embodiments, the configuration for attempting LTM change (attemptLTM-Switch) is a third UE variable, for example, VarAttemptLTM-Switch.

In some embodiments, the terminal device retains a configuration for attempting an LTM change (attemptLTM-Switch), including: the terminal device releases or clears all current dedicated wireless configurations associated with the cell group or MCG where the LTM cell change (LTM cell switch) is triggered, except for at least the following UE variables: a third UE variable (VarAttemptLTM-Switch), an LTM configuration variable (VarLTM-Config), a first LTM serving cell variable (VarLTM-ServingCellNoResetID), and a second LTM serving cell variable (VarLTM-ServingCellUE-MeasuredTA-ID).

Table 8 illustrates an example of performing an LTM cell change, where attemptLTM-Switch is stored as a UE variable.

Table 8

Table 9 illustrates an example of the third UE variable (VarAttemptLTM-Switch).

Table 9

As can be seen from the above embodiment, the third UE variable is associated with the attemptLTM-Switch. During an LTM cell change, this third UE variable is not released or cleared, meaning that the attemptLTM-Switch configuration remains. This allows the LTM candidate configuration to be used for rapid recovery after each LTM cell change, minimizing service interruptions caused by RRC reestablishment and improving the user experience.

In some embodiments, a configuration for attempting a LTM change (attemptLTM-Switch) is included in an RRC reconfiguration message.

In some embodiments, when the terminal device performs an LTM cell change (LTM cell switch), it applies the configuration for attempting LTM change (attemptLTM-Switch) corresponding to the LTM cell.

Table 10 illustrates an example of RRC reconfiguration.

Table 10

As can be seen from the above embodiment, the attemptLTM-Switch configuration is included in the RRC reconfiguration message. When an LTM cell change is executed, the attemptLTM-Switch configuration corresponding to the LTM cell is applied. This allows for fast recovery after each LTM cell change, minimizing service interruptions caused by RRC reestablishment and improving the user experience.

The above is a schematic illustration of the terminal device retaining attemptLTM-Switch, but the present application is not limited thereto.

In some embodiments, the configuration for attempting an LTM change (attemptLTM-Switch) includes a first parameter related to a serving cell and/or a second parameter related to a candidate cell.

In some embodiments, the value of the second parameter is the same as the value of the first parameter (or the first parameter is not configured/not stored), then the terminal device is configured (or it is believed that the terminal device is configured) for attempting LTM change (attemptLTM-Switch).

For example, when the terminal device performs an LTM cell switch, it stores the second parameter as a fourth UE variable, or replaces the value of the fourth UE variable with the second parameter.

For another example, when the terminal device performs an LTM cell change (LTM cell switch) and the cell associated with the second parameter is the target cell for performing the LTM cell change, the second parameter is stored as a fourth UE variable, or the value of the fourth UE variable is replaced by the second parameter.

For another example, when the terminal device performs an LTM cell change (LTM cell switch), it retains or does not release or clear the fourth UE variable.

In some embodiments, if the value of the second parameter is different from the value of the first parameter (or the first parameter is not configured/stored), the terminal device is not configured (or it is considered that the terminal device is not configured) for attempting LTM change (attemptLTM-Switch).

The above schematically illustrates the configuration reserved for attempting LTM changes (attemptLTM-Switch), and the triggering of LTM execution is described below. The following embodiments can be combined with any of the above embodiments, or can be executed separately.

FIG6 is an example diagram of LTM behavior on the UE side according to an embodiment of the present application, schematically illustrating the RRC/MAC/physical layers. As shown in FIG6 , upon receiving the LTM CSC MAC CE, the MAC layer indicates the target configuration ID to the upper layer (e.g., the RRC layer); based on the configuration ID, the RRC layer performs LTM execution and applies the configuration corresponding to the configuration ID. The RRC layer instructs the lower layer (e.g., the MAC layer) to perform a MAC reset; after completing the MAC reset as requested by the upper layer (e.g., the RRC layer), the terminal device processes the other fields in the LTM CSC MAC CE, including the TCI status, TA, and RA-related fields.

However, the above process has the following problems:

For example, there is a delay between receiving the LTM CSC MAC CE from the MCG (if DC is configured) and executing LTM and starting T304. During this time, the Master Cell Group (MCG) may be recovering from an MCG failure.

For another example, when receiving the LTM CSC MAC CE of the secondary cell group (SCG), MCG is in the process of recovering from an MCG failure.

In the above situation, LTM execution is meaningless and may cause delays in MCG failure recovery. During MCG failure recovery, MCG transmission is suspended. Therefore, delays in MCG failure recovery will cause greater business interruption.

In order to solve the above problems, the embodiments of the present application propose some solutions.

In some embodiments, when no MCG failure is detected, no MCG failure recovery is triggered, or not during MCG failure recovery, the UE initiates SCG and/or MCG LTM, or performs LTM execution on the SCG and/or MCG.

In some embodiments, during MCG failure recovery, the UE does not initiate SCG and/or MCG LTM, or does not perform LTM execution on the SCG and/or MCG.

In some embodiments, MCG failure includes MCG RLF or HOF.

In some embodiments, MCG failure recovery includes at least the MCG performing MCG failure information transmission.

In some embodiments, not being during MCG failure recovery includes at least T316 not being configured, or T316 not running.

In some embodiments, at least T316 is running during MCG failure recovery.

Table 11 illustrates an example where SCG LTM is not executed.

Table 11

In the above Table 11, "if timer T316 is not running" can also be replaced by "if timer T316 is not configured or is not running", but the present application is not limited to this.

Table 12 illustrates an example where neither MCG nor SCG LTM is executed.

Table 12

In the above Table 12, "if timer T316 is not running" can also be replaced by "if timer T316 is not configured or is not running", but the present application is not limited to this.

The above embodiments are merely exemplary of the present invention, but the present invention is not limited thereto. Appropriate modifications may be made based on the above embodiments. For example, the above embodiments may be used alone, or one or more of the above embodiments may be combined.

Through the embodiments of the present application, the terminal device executes an LTM cell change (LTM cell switch), wherein the configuration for attempting the LTM change (attemptLTM-Switch) is retained. Therefore, after each LTM cell change is executed, the LTM candidate configuration can still be used for fast recovery from failure, reducing service interruption caused by RRC reconstruction, thereby improving user experience.

Embodiments of the second aspect

The embodiment of the present application provides a configuration method for cell change, which is described from the perspective of a network device. The embodiment of the second aspect can be combined with the embodiment of the first aspect, and the same contents as the embodiment of the first aspect will not be repeated.

FIG7 is a schematic diagram of a configuration method for cell change according to an embodiment of the present application. As shown in FIG7 , the method includes:

701. The network device sends configuration information of Layer 1/Layer 2 Triggered Mobility (LTM) to the terminal device.

The configuration for attempting LTM change (attemptLTM-Switch) is included in the configuration information, or the configuration for attempting LTM change (attemptLTM-Switch) is included in the first information of the configuration information, or the configuration for attempting LTM change (attemptLTM-Switch) is included in the RRC reconfiguration message.

It is worth noting that FIG7 above is only a schematic illustration of the embodiment of the present application, but the present application is not limited thereto. For example, the execution order of each operation can be appropriately adjusted, and other operations can be added or some operations can be reduced. Those skilled in the art can make appropriate modifications based on the above content. It is not limited to the description in FIG7 above.

In some embodiments, the configuration for attempting LTM switching (attemptLTM-Switch) includes a first parameter related to the serving cell and/or a second parameter related to the candidate cell. The specific contents of the parameters and configuration information can be referred to in the above embodiments.

The above embodiments are merely exemplary of the present invention, but the present invention is not limited thereto. Appropriate modifications may be made based on the above embodiments. For example, the above embodiments may be used alone, or one or more of the above embodiments may be combined.

Through the embodiments of the present application, the terminal device executes an LTM cell change (LTM cell switch), wherein the configuration for attempting the LTM change (attemptLTM-Switch) is retained. Therefore, after each LTM cell change is executed, the LTM candidate configuration can still be used for fast recovery from failure, reducing service interruption caused by RRC reconstruction, thereby improving user experience.

Embodiments of the third aspect

The embodiment of the present application provides a cell change execution device. The device may be, for example, a terminal device, or one or more components or assemblies configured in the terminal device. The same contents as those in the embodiment of the first aspect will not be repeated here.

FIG8 is a schematic diagram of a cell change execution device according to an embodiment of the present application. As shown in FIG8 , the cell change execution device 800 includes:

a receiving unit 801 configured to receive configuration information of Layer 1/Layer 2 Triggered Mobility (LTM) sent by a network device;

A processing unit 802, which performs an LTM cell change (LTM cell switch), wherein the terminal device retains a configuration for attempting an LTM change (attemptLTM-Switch).

In some embodiments, the terminal device retains a configuration for attempting an LTM change (attemptLTM-Switch), including: the terminal device does not release or clear the configuration for attempting an LTM change (attemptLTM-Switch);

Alternatively, the terminal device releases or clears the current dedicated radio configuration associated with the cell group or MCG where the LTM cell change (LTM cell switch) is triggered, except for at least the configuration for attempting the LTM change (attemptLTM-Switch).

In some embodiments, the configuration for attempting LTM change (attemptLTM-Switch) is stored in a first UE variable.

In some embodiments, the first UE variable is at least one of the following: an LTM configuration variable (VarLTM-Config), a first LTM serving cell variable (VarLTM-ServingCellNoResetID), and a second LTM serving cell variable (VarLTM-ServingCellUE-MeasuredTA-ID).

In some embodiments, the terminal device retains the configuration for attempting an LTM change (attemptLTM-Switch), including: the terminal device releases or clears the current dedicated wireless configuration associated with the cell group or MCG where the LTM cell change (LTM cell switch) is triggered, except for the first UE variable.

In some embodiments, the configuration for attempting LTM change (attemptLTM-Switch) is configured in the configuration information (LTM-Config) of LTM, then the terminal device stores the configuration for attempting LTM change (attemptLTM-Switch) or related variables in the first UE variable; and/or

If the configuration for attempting LTM change (attemptLTM-Switch) is not configured in the configuration information (LTM-Config) of the LTM, the terminal device removes/releases/clears the configuration for attempting LTM change (attemptLTM-Switch) in the first UE variable.

In some embodiments, the configuration for attempting LTM change (attemptLTM-Switch) is configured in the configuration information (LTM-Config) of LTM and there is no configuration for attempting LTM change (attemptLTM-Switch) in the first UE variable, then the terminal device stores the configuration for attempting LTM change (attemptLTM-Switch) in the first UE variable; and/or

The configuration for attempting LTM changes (attemptLTM-Switch) is not configured in the configuration information (LTM-Config) of the LTM and the configuration for attempting LTM changes (attemptLTM-Switch) is present in the first UE variable, then the terminal device removes (remove)/releases/clears the configuration for attempting LTM changes (attemptLTM-Switch) in the first UE variable.

In some embodiments, the configuration for attempting LTM change (attemptLTM-Switch) is stored in the first information of the second UE variable.

In some embodiments, the second UE variable is an LTM configuration variable (VarLTM-Config).

In some embodiments, the first information is at least one of the following: a reference configuration (ReferenceConfiguration), an LTM candidate configuration (LTM-Candidate).

In some embodiments, the terminal device retains a configuration for attempting LTM changes (attemptLTM-Switch), including: the LTM candidate configuration (LTM-Candidate) includes the configuration for attempting LTM changes (attemptLTM-Switch), then the terminal device receives the configuration for attempting The configuration of the LTM change (attemptLTM-Switch) is added to the first information of the second UE variable.

In some embodiments, the configuration for attempting LTM change (attemptLTM-Switch) is a third UE variable.

In some embodiments, the terminal device retains the configuration for attempting the LTM change (attemptLTM-Switch), including: the terminal device releases or clears the current dedicated wireless configuration associated with the cell group or MCG where the LTM cell change (LTM cell switch) is triggered, except for at least the following UE variables: a third UE variable (VarAttemptLTM-Switch), an LTM configuration variable (VarLTM-Config), a first LTM serving cell variable (VarLTM-ServingCellNoResetID), and a second LTM serving cell variable (VarLTM-ServingCellUE-MeasuredTA-ID).

In some embodiments, the configuration for attempting LTM change (attemptLTM-Switch) is included in an RRC reconfiguration message.

In some embodiments, when the terminal device performs an LTM cell change (LTM cell switch), it applies the configuration for attempting LTM change (attemptLTM-Switch) corresponding to the LTM cell.

In some embodiments, the configuration for attempting LTM change (attemptLTM-Switch) includes a first parameter related to a serving cell and/or a second parameter related to a candidate cell.

In some embodiments, the value of the second parameter is the same as the value of the first parameter, and the terminal device is configured with a configuration for attempting an LTM change (attemptLTM-Switch).

In some embodiments, when the terminal device performs an LTM cell switch, the terminal device stores the second parameter as a fourth UE variable, or replaces the value of the fourth UE variable with the second parameter.

In some embodiments, when performing an LTM cell change (LTM cell switch), the terminal device retains or does not release or clear the fourth UE variable.

In some embodiments, if the value of the second parameter is different from the value of the first parameter, the terminal device is not configured to attempt an LTM switch (attemptLTM-Switch).

It is worth noting that the above only describes the components or modules related to the present application, but the present application is not limited thereto. The cell change execution device 800 may also include other components or modules. For the specific contents of these components or modules, reference may be made to the relevant art.

In addition, for the sake of simplicity, FIG8 only illustrates the connection relationship or signal direction between various components or modules, but it should be clear to those skilled in the art that various related technologies such as bus connection can be used. The above components or modules can be implemented by hardware facilities such as processors, memories, transmitters, and receivers. Now; the implementation of this application does not limit this.

Through the embodiments of the present application, the terminal device executes an LTM cell change (LTM cell switch), wherein the configuration for attempting the LTM change (attemptLTM-Switch) is retained. Therefore, after each LTM cell change is executed, the LTM candidate configuration can still be used for fast recovery from failure, reducing service interruption caused by RRC reconstruction, thereby improving user experience.

Embodiments of the fourth aspect

The embodiment of the present application provides a cell change configuration device. The device may be, for example, a network device, or one or more components or assemblies configured in the network device. The contents that are the same as those in the first to third aspects of the embodiment are not repeated here.

FIG9 is a schematic diagram of a cell change configuration device according to an embodiment of the present application. As shown in FIG9 , the cell change configuration device 900 includes:

A sending unit 901, which sends configuration information of Layer 1/Layer 2 Triggered Mobility (LTM) to a terminal device;

The configuration for attempting LTM change (attemptLTM-Switch) is included in the configuration information, or the configuration for attempting LTM change (attemptLTM-Switch) is included in the first information of the configuration information, or the configuration for attempting LTM change (attemptLTM-Switch) is included in the RRC reconfiguration message.

It is worth noting that the above only describes the components or modules related to the present application, but the present application is not limited thereto. The cell change configuration device 900 may also include other components or modules. For the specific contents of these components or modules, reference may be made to the relevant art.

In addition, for the sake of simplicity, FIG9 only illustrates the connection relationship or signal direction between various components or modules. However, it should be clear to those skilled in the art that various related technologies such as bus connection can be used. The above-mentioned components or modules can be implemented by hardware facilities such as processors, memories, transmitters, and receivers; the implementation of this application is not limited to this.

Through the embodiments of the present application, the terminal device performs an LTM cell change (LTM cell switch), wherein the configuration for attempting the LTM change (attemptLTM-Switch) is retained. Therefore, after each LTM cell change is executed, the LTM candidate configuration can still be used for fast recovery of failure, reducing service interruption caused by RRC reconstruction, thereby improving user experience.

Embodiments of the fifth aspect

An embodiment of the present application also provides a communication system, and reference may be made to FIG2 . The contents that are the same as those in the first to fourth aspects of the embodiments will not be repeated.

In some embodiments, the communication system 100 may include at least:

A network device that sends Layer 1/Layer 2 Triggered Mobility (LTM) configuration information to a terminal device;

A terminal device receives configuration information of Layer 1/Layer 2 Triggered Mobility (LTM) sent by the network device and performs an LTM cell change (LTM cell switch), wherein the terminal device retains a configuration for attempting the LTM change (attemptLTM-Switch).

The embodiment of the present application also provides a terminal device, but the present application is not limited thereto and may also be other devices.

Figure 10 is a schematic diagram of a terminal device according to an embodiment of the present application. As shown in Figure 10 , terminal device 1000 may include a processor 1010 and a memory 1020. Memory 1020 stores data and programs and is coupled to processor 1010. It should be noted that this diagram is exemplary; other types of structures may be used to supplement or replace this structure to implement telecommunication or other functions.

For example, the processor 1010 may be configured to execute a program to implement the method for executing a cell change as described in the embodiment of the first aspect. For example, the processor 1010 may be configured to perform the following control: receiving configuration information of layer 1/layer 2 triggered mobility (LTM) sent by a network device; and executing an LTM cell change (LTM cell switch), wherein a configuration for attempting an LTM change (attempt LTM-Switch) is retained.

As shown in Figure 10 , the terminal device 1000 may further include: a communication module 1030, an input unit 1040, a display 1050, and a power supply 1060. The functions of these components are similar to those in the prior art and are not described in detail here. It is worth noting that the terminal device 1000 does not necessarily include all of the components shown in Figure 10 , and these components are not essential. Furthermore, the terminal device 1000 may also include components not shown in Figure 10 , for which reference may be made to the prior art.

An embodiment of the present application further provides a network device, which may be, for example, a base station, but the present application is not limited thereto and may also be other network devices.

Figure 11 is a schematic diagram illustrating the structure of a network device according to an embodiment of the present application. As shown in Figure 11 , network device 1100 may include a processor 1110 (e.g., a central processing unit (CPU)) and a memory 1120 ; the memory 1120 is coupled to the processor 1110 . The memory 1120 may store various data and may also store an information processing program 1130 , which is executed under the control of the processor 1110 .

For example, the processor 1110 may be configured to execute a program to implement the small Configuration method for zone change. For example, the processor 1110 may be configured to perform the following control: sending configuration information of layer 1/layer 2 triggered mobility (LTM) to the terminal device; wherein the configuration for attempting LTM change (attemptLTM-Switch) is included in the configuration information, or the configuration for attempting LTM change (attemptLTM-Switch) is included in the first information of the configuration information, or the configuration for attempting LTM change (attemptLTM-Switch) is included in the RRC reconfiguration message.

In addition, as shown in FIG11 , the network device 1100 may further include: a transceiver 1140 and an antenna 1150, etc.; wherein, the functions of the above components are similar to those in the prior art and are not described in detail here. It is worth noting that the network device 1100 does not necessarily include all the components shown in FIG11 ; in addition, the network device 1100 may also include components not shown in FIG11 , and reference may be made to the prior art for details.

An embodiment of the present application also provides a computer program, wherein when the program is executed in a terminal device, the program causes the terminal device to execute the method for executing the cell change described in the embodiment of the first aspect.

An embodiment of the present application also provides a storage medium storing a computer program, wherein the computer program enables a terminal device to execute the method for executing a cell change as described in the embodiment of the first aspect.

An embodiment of the present application also provides a computer program, wherein when the program is executed in a network device, the program causes the network device to execute the cell change configuration method described in the embodiment of the second aspect.

An embodiment of the present application also provides a storage medium storing a computer program, wherein the computer program enables a network device to execute the cell change configuration method described in the embodiment of the second aspect.

The above devices and methods of the present application can be implemented by hardware or by a combination of hardware and software. The present application relates to such a computer-readable program that, when executed by a logic component, enables the logic component to implement the devices or components described above, or enables the logic component to implement the various methods or steps described above. The present application also relates to a storage medium for storing the above program, such as a hard disk, a magnetic disk, an optical disk, a DVD, a flash memory, etc.

The method/device described in conjunction with the embodiments of the present application can be directly embodied as hardware, a software module executed by a processor, or a combination of the two. For example, one or more of the functional block diagrams shown in the figure and/or one or more combinations of functional block diagrams can correspond to various software modules of the computer program flow or to various hardware modules. These software modules can respectively correspond to the various steps shown in the figure. These hardware modules can be implemented by solidifying these software modules, for example, using a field programmable gate array (FPGA).

The software module may be located in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, removable disk, CD-ROM or any other form of storage medium known in the art. A storage medium may be coupled to the processor so that the processor can read information from the storage medium. Information can be stored in the storage medium, and information can be written to the storage medium; or the storage medium can be an integral part of the processor. The processor and storage medium can be located in an ASIC. The software module can be stored in the memory of the mobile terminal or in a memory card that can be inserted into the mobile terminal. For example, if the device (such as a mobile terminal) uses a large-capacity MEGA-SIM card or a large-capacity flash memory device, the software module can be stored in the MEGA-SIM card or the large-capacity flash memory device.

One or more of the functional blocks and/or one or more combinations of functional blocks described in the accompanying drawings may be implemented as a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic device, a discrete gate or transistor logic device, a discrete hardware component, or any appropriate combination thereof for performing the functions described in this application. One or more of the functional blocks and/or one or more combinations of functional blocks described in the accompanying drawings may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in communication with a DSP, or any other such configuration.

The present application has been described above in conjunction with specific embodiments. However, those skilled in the art should understand that these descriptions are merely illustrative and are not intended to limit the scope of protection of the present application. Those skilled in the art may make various modifications and variations to the present application based on the spirit and principles of the present application, and such modifications and variations are also within the scope of the present application.

Regarding the implementation methods including the above embodiments, the following additional notes are also disclosed:

1. A method for executing a cell switch, comprising:

The terminal device receives configuration information of Layer 1/Layer 2 Triggered Mobility (LTM) sent by the network device;

The terminal device performs an LTM cell change (LTM cell switch), wherein the terminal device retains a configuration for attempting an LTM change (attemptLTM-Switch).

2. A cell switch configuration method, comprising:

The network device sends Layer 1/Layer 2 Triggered Mobility (LTM) configuration information to the terminal device;

The configuration for attempting LTM change (attemptLTM-Switch) is included in the configuration information, or the configuration for attempting LTM change (attemptLTM-Switch) is included in the first information of the configuration information, or the configuration for attempting LTM change (attemptLTM-Switch) is included in the RRC reconfiguration message.

3. A terminal device comprising a memory and a processor, wherein the memory stores a computer program, and the processor is configured to execute the computer program to implement the cell switch as described in Supplement 1. Execution method.

4. A network device comprising a memory and a processor, wherein the memory stores a computer program, and the processor is configured to execute the computer program to implement the cell change (cell switch) configuration method as described in Note 2.

5. A computer program product, comprising at least a computer program, which, when executed by a processor, enables a terminal device to execute the cell change (cell switch) execution method as described in Note 1.

6. A computer program product comprising at least a computer program, which, when executed by a processor, enables a network device to execute the cell change (cell switch) configuration method as described in Note 2.

7. A method for triggering an LTM, comprising:

The terminal device initiates SCG and/or MCG LTM, or performs LTM execution on SCG and/or MCG, when no MCG failure is detected and no MCG failure recovery is triggered, or when the terminal device is not in the MCG failure recovery period;

Alternatively, during MCG failure recovery, the terminal device does not initiate SCG and/or MCG LTM, or does not perform LTM execution on SCG and/or MCG.

8. The method according to Note 7, wherein the MCG failure includes MCG RLF or HOF.

9. The method according to Note 7, wherein the MCG failure recovery at least includes the MCG performing MCG failure information transmission.

10. The method according to Note 7, wherein not being during MCG failure recovery at least includes T316 not being configured or T316 not running;

and/or

At least T316 is running during MCG failure recovery.

Claims (20)

A cell change execution device, comprising: A receiving unit, configured to receive the LTM configuration information sent by the network device; A processing unit that performs an LTM cell change, wherein the terminal device retains a configuration for attempting the LTM change. The apparatus of claim 1, wherein the terminal device retains a configuration for attempting an LTM change, comprising: The terminal device does not release or clear the configuration for attempting the LTM change; Alternatively, the terminal device releases or clears the current dedicated radio configuration associated with the cell group or MCG where the LTM cell change is triggered, at least except for the configuration used to attempt the LTM change. The apparatus of claim 1, wherein the configuration for attempting an LTM change is stored in a first UE variable; The first UE variable is at least one of the following: an LTM configuration variable, a first LTM serving cell variable, and a second LTM serving cell variable. The apparatus of claim 3, wherein the terminal device retains a configuration for attempting an LTM change, comprising: The terminal device releases or clears the current dedicated radio configuration associated with the cell group or MCG where the LTM cell change is triggered, except for the first UE variable. The device according to claim 3, wherein The configuration for attempting LTM change is configured in the configuration information of LTM, and the terminal device stores the configuration for attempting LTM change or related variables in the first UE variable; and/or If the configuration for attempting LTM change is not configured in the configuration information of the LTM, the terminal device removes/releases/clears the configuration for attempting LTM change in the first UE variable. The device according to claim 3, wherein The configuration for attempting LTM change is configured in the configuration information of LTM and there is no configuration for attempting LTM change in the first UE variable, then the terminal device stores the configuration for attempting LTM change in the first UE variable; and/or The configuration for attempting an LTM change is not configured in the configuration information of the LTM and in the first If there is the configuration for attempting LTM change in the UE variable, the terminal device removes/releases/clears the configuration for attempting LTM change in the first UE variable. The apparatus of claim 1, wherein the configuration for attempting an LTM change is stored in the first information of the second UE variable. The apparatus according to claim 7, wherein the second UE variable is an LTM configuration variable; The first information is at least one of the following: a reference configuration, and an LTM candidate configuration. The apparatus of claim 7, wherein the terminal device retains a configuration for attempting an LTM change, comprising: If the LTM candidate configuration includes the configuration for attempting LTM change, the terminal device adds the received configuration for attempting LTM change to the first information of the second UE variable. The apparatus of claim 1, wherein the configuration for attempting an LTM change is a third UE variable. The apparatus of claim 10, wherein the terminal device retains a configuration for attempting an LTM change, comprising: The terminal device releases or clears the current dedicated wireless configuration associated with the cell group or MCG where the LTM cell change is triggered, except for at least the following UE variables: a third UE variable, an LTM configuration variable, a first LTM serving cell variable, and a second LTM serving cell variable. The apparatus of claim 1, wherein the configuration for attempting an LTM change is included in an RRC reconfiguration message. The apparatus according to claim 12, wherein, when performing the LTM cell change, the terminal device applies the configuration for attempting the LTM change corresponding to the LTM cell. The apparatus according to claim 1, wherein the configuration for attempting an LTM change comprises a first parameter related to a serving cell and/or a second parameter related to a candidate cell. The apparatus of claim 14, wherein if the value of the second parameter is the same as the value of the first parameter, the terminal device is configured to attempt an LTM change. The apparatus according to claim 15, wherein the terminal device stores the second parameter as a fourth UE variable or replaces the value of the fourth UE variable with the second parameter when performing an LTM cell change. The apparatus according to claim 16, wherein the terminal device retains, does not release, or does not clear the fourth UE variable when performing an LTM cell change. The apparatus of claim 14, wherein if the value of the second parameter is different from the value of the first parameter, the terminal device is not configured to attempt an LTM change. A cell change configuration device, comprising: A sending unit, configured to send LTM configuration information to a terminal device; The configuration for attempting LTM change is included in the configuration information, or the configuration for attempting LTM change is included in the first information of the configuration information, or the configuration for attempting LTM change is included in the RRC reconfiguration message. A communication system comprising: A network device that sends LTM configuration information to a terminal device; The terminal device receives the LTM configuration information sent by the network device and performs LTM cell change, wherein the terminal device retains the configuration for attempting the LTM change.