Wireless communication methods, terminal devices and network devices

Abstract

Provided are wireless communication methods, terminal devices and network devices. A wireless communication method comprises: upon occurrence of RLF and / or cell handover procedure failure, a terminal device selecting a first target cell; and when a first condition is met, the terminal device applying a configuration of the first target cell. Compared with methods in the related art, the method provided in an embodiment of the present application can be applied to any type of cell handover procedure failure, and can realize fast failure recovery of a communication link when a first condition is met, thereby improving the continuity and stability of communications.

Description

Wireless communication methods, terminal equipment and network equipment Technical Field

[0001] This application relates to the field of communication technology, and more specifically, to wireless communication methods, terminal devices, and network devices. Background Technology

[0002] In wireless communication, radio link failure (RLF) and / or cell handover failure are common problems that can be caused by various factors, such as insufficient signal strength, network configuration errors, base station malfunctions, or interference. These failures lead to communication interruptions and severely impact user experience. Therefore, effectively addressing these failures to ensure communication continuity and stability is a crucial issue that urgently needs to be addressed in the field of wireless communication. Summary of the Invention

[0003] This application provides a wireless communication method, terminal device, and network device. The various aspects covered by this application are described below.

[0004] In a first aspect, a wireless communication method is provided, comprising: in the event of an RLF and / or cell handover process failure, a terminal device selecting a first target cell; and, if a first condition is met, the terminal device applying the configuration of the first target cell.

[0005] In a second aspect, a wireless communication method is provided, comprising: a network device sending a first parameter to a terminal device; wherein the first parameter is used to generate a key corresponding to a first target cell, the first target cell being a cell selected by the terminal device in the event of an RLF and / or cell handover failure.

[0006] Thirdly, a terminal device is provided that, in the event of an RLF and / or cell handover failure, the terminal device selects a first target cell; and, if a first condition is met, the terminal device applies the configuration of the first target cell.

[0007] Fourthly, a network device is provided, comprising: a transmitting unit, configured to transmit a first parameter to a terminal device; wherein the first parameter is used to generate a key corresponding to a first target cell, the first target cell being a cell selected by the terminal device in the event of an RLF and / or cell handover failure.

[0008] Fifthly, a terminal device is provided, including a transceiver, a memory, and a processor, wherein the memory is used to store a program, the processor is used to invoke the program in the memory, and to control the transceiver to receive or send signals so that the terminal device performs some or all of the steps in the method of the first aspect.

[0009] In a sixth aspect, a network device is provided, including a transceiver, a memory, and a processor, wherein the memory is used to store a program, the processor is used to invoke the program in the memory, and to control the transceiver to receive or transmit signals so that the network device performs some or all of the steps in the method of the second aspect.

[0010] In a seventh aspect, a communication system is provided, which includes the aforementioned terminal device and / or network device. In another possible design, the system may further include other devices that interact with the terminal device or network device as described in the embodiments of this application.

[0011] Eighthly, a computer-readable storage medium is provided, the computer-readable storage medium storing a computer program that causes a terminal device and / or a network device to perform some or all of the steps in the methods of the above aspects.

[0012] Ninthly, embodiments of this application provide a computer program product, wherein the computer program product includes a non-transitory computer-readable storage medium storing a computer program operable to cause a terminal device and / or a network device to perform some or all of the steps of the methods described in the foregoing aspects. In some implementations, the computer program product may be a software installation package.

[0013] In a tenth aspect, embodiments of this application provide a chip including a memory and a processor, the processor being able to call and run a computer program from the memory to implement some or all of the steps described in the methods of the foregoing aspects.

[0014] In this embodiment, when an RLF (Recurrent Least Frequent Failure) and / or cell handover failure occurs, the terminal device selects a first target cell. Upon meeting a first condition, the terminal device applies the configuration information of the first target cell to quickly restore the communication link. Compared to related technologies, the method provided in this embodiment can be applied to any type of cell handover failure. When the first condition is met, fast failure recovery of the communication link can be achieved, thereby improving the continuity and stability of communication. Attached Figure Description

[0015] Figure 1 shows the wireless communication system 100 used in an embodiment of this application.

[0016] Figure 2 is a schematic flowchart of the L1 / L2 triggered mobility (LTM) process.

[0017] Figure 3 is a schematic flowchart of a wireless communication method according to an embodiment of this application.

[0018] Figure 4 is a schematic flowchart of another wireless communication method according to an embodiment of this application.

[0019] Figure 5 is a schematic diagram of a terminal device according to an embodiment of this application.

[0020] Figure 6 is a schematic diagram of a network device according to an embodiment of this application.

[0021] Figure 7 is a schematic structural diagram of a communication device according to an embodiment of this application. Detailed Implementation

[0022] The technical solutions in this application will now be described with reference to the accompanying drawings.

[0023] Communication system

[0024] Figure 1 illustrates a wireless communication system 100 according to an embodiment of this application. The wireless communication system 100 may include a network device 110 and a terminal device 120. The network device 110 may be a device that communicates with the terminal device 120. The network device 110 may provide communication coverage for a specific geographical area and may communicate with the terminal device 120 located within that coverage area.

[0025] Figure 1 illustrates an exemplary network device and two terminals. Optionally, the wireless communication system 100 may include multiple network devices, and each network device may include other terminal devices within its coverage area. This application embodiment does not limit this.

[0026] Optionally, the wireless communication system 100 may also include other network entities such as a network controller and a mobility management entity, which is not limited in this embodiment.

[0027] It should be understood that the technical solutions of the embodiments of this application can be applied to various communication systems, such as: 5th generation (5G) systems or new radio (NR), long term evolution (LTE) systems, LTE frequency division duplex (FDD) systems, LTE time division duplex (TDD) systems, etc. The technical solutions provided in this application can also be applied to future communication systems, such as 6th generation mobile communication systems, satellite communication systems, and so on.

[0028] The terminal device in this application embodiment can also be referred to as user equipment (UE), access terminal, user unit, user station, mobile station, mobile station (MS), mobile terminal (MT), remote station, remote terminal, mobile device, user terminal, terminal, wireless communication device, user agent, or user device. The terminal device in this application embodiment can be a device that provides voice and / or data connectivity to a user, and can be used to connect people, objects, and machines, such as a handheld device with wireless connectivity, vehicle-mounted device, etc. The terminal devices in the embodiments of this application can be mobile phones, tablets, laptops, PDAs, mobile internet devices (MIDs), wearable devices, virtual reality (VR) devices, augmented reality (AR) devices, wireless terminals in industrial control, self-driving, remote medical surgery, smart grids, transportation safety, smart cities, and smart homes, etc. Optionally, the UE can act as a base station. For example, the UE can act as a scheduling entity, providing sidelink signals between UEs in V2X or D2D, etc. For example, cellular phones and cars communicate with each other using sidelink signals. Cellular phones and smart home devices communicate without relaying communication signals through a base station.

[0029] The network device in this application embodiment can be a device for communicating with a terminal device. This network device can also be called an access network device or a wireless access network device, such as a base station. In this application embodiment, the network device can refer to a radio access network (RAN) node (or device) that connects the terminal device to the wireless network. A base station can broadly encompass, or be replaced by, various names including: NodeB, evolved NodeB (eNB), next-generation NodeB (gNB), relay station, transmitting and receiving point (TRP), transmitting point (TP), master MeNB, auxiliary SeNB, multi-mode radio (MSR) node, home base station, network controller, access node, wireless node, access point (AP), transmission node, transceiver node, baseband unit (BBU), remote radio unit (RRU), active antenna unit (AAU), remote radio head (RRH), central unit (CU), distributed unit (DU), positioning node, etc. A base station can be a macro base station, micro base station, relay node, donor node, or similar, or a combination thereof. A base station can also refer to a communication module, modem, or chip installed within the aforementioned equipment or apparatus. Base stations can also be mobile switching centers, devices that perform base station functions in device-to-device (D2D), vehicle-to-everything (V2X), and machine-to-machine (M2M) communications, network-side devices in 6G networks, and devices that perform base station functions in future communication systems. Base stations can support networks using the same or different access technologies. The embodiments of this application do not limit the specific technologies or device forms used in the network equipment.

[0030] Base stations can be fixed or mobile. For example, a helicopter or drone can be configured to act as a mobile base station, and one or more cells can move depending on the location of the mobile base station. In other examples, a helicopter or drone can be configured as a device to communicate with another base station.

[0031] In some deployments, the network device in this application embodiment may refer to a CU or a DU, or the network device may include both a CU and a DU. The gNB may also include an AAU.

[0032] Network devices and terminal devices can be deployed on land, including indoors or outdoors, handheld or vehicle-mounted; they can also be deployed on water; and they can also be deployed in the air on airplanes, balloons, and satellites. This application does not limit the scenario in which the network devices and terminal devices are located.

[0033] It should be understood that all or part of the functions of the communication device in this application can also be implemented by software functions running on hardware, or by virtualization functions instantiated on a platform (e.g., a cloud platform).

[0034] LTM

[0035] To further reduce handover latency and ensure service continuity, LTM (Last Time To Meet) has been introduced in some protocols (e.g., 3GPP R18). For ease of understanding, the LTM process will be explained below with reference to Figure 2.

[0036] As shown in Figure 2, the LTM process can include the LTM preparation phase, the LTM execution phase, and the LTM completion phase.

[0037] During the LTM preparation phase, LTM may include steps S210 to S230.

[0038] In step S210, the terminal device reports the measurement results to the network device. These measurement results can be Layer 3 measurements. The network device can then determine whether to initiate an LTM procedure and trigger candidate cell preparation based on the measurement results reported by the terminal device.

[0039] In step S220, the network device sends an RRC message containing the LTM configuration (or LTM candidate configuration) to the terminal device. For example, the network device may send a radio resource control reconfiguration (RRCReconfiguration) message to the terminal device to indicate the LTM configuration.

[0040] In some embodiments, the LTM configuration sent by the network device to the terminal device may include the LTM configuration corresponding to one or more candidate cells.

[0041] In some embodiments, the terminal device may also store the LTM configuration indicated by the network device.

[0042] In step S230, the terminal device sends a Radio Resource Control Reconfiguration Complete (RRCReconfigurationComplete) message to the network device.

[0043] In some embodiments, referring to steps S240a and S240b, after the terminal device completes the LTM preparation phase, it can perform uplink / downlink synchronization with the candidate cell in advance to shorten the interruption latency during the handover process. This process can be understood as the early synchronization phase.

[0044] During the LTM execution phase, LTM may include steps S250 and S260.

[0045] In step S250, the terminal device performs Layer 1 measurement on each candidate cell and reports the Layer 1 measurement results to the network device.

[0046] In some implementations, after receiving the Layer 1 measurement results reported by the terminal device, the network device can determine the target cell based on the Layer 1 measurement results.

[0047] In step S260, the network device sends a cell handover command to the terminal device to instruct the terminal device to hand over to the target cell. For example, the network device can instruct the terminal device to hand over to the target cell through a medium access control element (MAC CE).

[0048] In some implementations, after receiving a cell handover command, the terminal device can detach from the source cell and apply the target configuration (i.e., apply the configuration of the target cell).

[0049] In some embodiments, if the terminal device does not currently have a valid timing advance (TA) or transmission configuration indicator (TCI) status identifier for the target cell, the terminal device may also execute step S270 during the LTM execution phase. In step S270, the terminal device initiates a random access procedure to the target cell.

[0050] During the LTM completion phase, LTM may include step S280.

[0051] In step S280, the terminal device indicates that LTM is complete. For example, the terminal device may send an indication message that LTM has been successfully completed to the target cell.

[0052] It should be noted that after completing one LTM process, multiple subsequent LTM processes can be performed based on the candidate cell configuration received in step S220, that is, steps S240 to S280 above can be repeated.

[0053] Fast failure recovery

[0054] Fast failure recovery (FFR) is a technique used to optimize failure recovery in wireless communication. In the complex environment of wireless communication, communication links face numerous challenges and may fail due to various factors. When an RLF or LTM failure occurs, the communication system triggers a fast failure recovery mechanism. For example, after detecting a link failure, the terminal device can trigger radio resource control (RRC) connection re-establishment.

[0055] During RRC reconstruction, the terminal device first performs cell reselection.

[0056] If the terminal device selects an LTM candidate cell, and the LTM candidate cell is configured to support fast failure recovery, the terminal device can directly apply the target cell's configuration information to quickly restore the communication link. This means that the terminal device does not need to re-perform the complex RRC connection establishment process, but can directly utilize pre-configured parameters (such as radio configuration, security context, etc.) to quickly access the target cell, reducing recovery time. The LTM candidate cell is a cell pre-configured by the network device during the LTM preparation phase. For example, the network device can configure the LTM candidate cell in the Radio Resource Control reconfiguration message.

[0057] In wireless communication, a key is an encryption parameter negotiated and generated between a terminal device and a network device. For example, keys can be used for encryption, security authentication, and integrity protection, ensuring the security, privacy, and integrity of data during transmission. As the communication environment changes or security policies are updated, the key needs to be updated accordingly. For instance, when a terminal device switches to a new network node (such as a cell managed by a different CU), it may need to update the key to adapt to the new security environment.

[0058] In some implementations, the key update process can be driven by the next-hop chaining counter (NCC). In other words, the NCC can be used to manage key updates. In some embodiments, the NCC can be combined with the current key to generate a new key through a key derivation function, ensuring key synchronization between the terminal device and the network device. When a terminal device switches from one cell to another, the value of the NCC can be used to determine whether key derivation should be performed based on the current key. In some embodiments, the value of the NCC can be used to trigger the key update process. For example, when the value of the NCC reaches a preset threshold or meets specific conditions, a key update is triggered, generating a new key and applying it to the communication link.

[0059] In some scenarios, for intra-CU LTM processes, multiple LTM candidate cells are managed by the same CU, and the fast failure recovery process does not involve key updates. That is, when a terminal device performs a handover between these candidate cells, since the target cell selected by the terminal device belongs to the same CU as the source cell, the terminal device can continue to use the source cell's key in the target cell without needing a key update. Here, the source cell can refer to the cell the terminal device is currently connected to. For example, during a handover process, when the terminal device switches from one cell to another, the original cell can be called the source cell, and the newly switched cell can be called the target cell.

[0060] In other scenarios, such as the 3GPP Release 19 Mobility project, LTM is further extended to inter-CU LTM scenarios, where multiple LTM candidate cells can be managed by different CUs. Because CU changes are involved, the fast failure recovery process for cross-CU scenarios requires key updates. For example, a key update is needed when a terminal device performs a handover between LTM candidate cells.

[0061] In some embodiments, such as in a master cell group (MCG) LTM scenario between CUs, the NCC can be provided by an LTM cell switch command, which can be carried via MAC CE. After receiving the LTM cell switch command, the terminal device can update the key according to the NCC value to ensure secure communication in the target cell.

[0062] For example, in a secondary cell group (SCG) LTM scenario between CUs, key update information can be pre-configured via RRC. Pre-configuring key update information via RRC signaling can reduce MAC layer signaling overhead while ensuring correct key updates during cell handover.

[0063] In wireless communication, various factors can lead to RLF (Recurrent Least Function Failure) and / or various types of cell handover failures. How to effectively handle these failures and quickly restore communication links is a crucial problem that urgently needs to be solved in the field of wireless communication. For example, when an LTM (Low-Terminal Module) handover fails between CUs, restoring the communication link involves key updates. However, in this scenario, the NCC (Non-Committed Control Code) used for key updates is provided by the LTM cell handover command, rather than being pre-configured. Therefore, the terminal device can only obtain the NCC and complete the key update during handover. However, once a communication anomaly occurs, such as an RLF and / or LTM failure, the terminal device cannot receive the cell handover command containing the NCC, thus failing to complete the key update. This directly affects the terminal device's access and communication continuity in the target cell.

[0064] Therefore, to address the aforementioned problems, this application provides a wireless communication method. When an RLF (Recurrent Link Failure) and / or cell handover failure occurs, the terminal device selects a first target cell. Upon meeting a specific first condition, the terminal device applies the configuration information of the first target cell to quickly restore the communication link. Compared to related technologies, the method provided in this application can be applied to any type of cell handover failure. Under the condition of meeting the first condition, rapid recovery of the communication link can be achieved, thereby improving the continuity and stability of communication.

[0065] For ease of understanding, the wireless communication method of this application embodiment is described below with reference to FIG3. The method shown in FIG3 includes steps S310 and S320.

[0066] In step S310, the terminal device selects the first target cell.

[0067] In some embodiments, in the event of an RLF (Recurrent Least Frequent Failure) and / or a cell handover failure, the terminal device may initiate a first procedure. During this first procedure, the terminal device may select a first target cell. Exemplarily, the first target cell may be selected through a cell reselection procedure. This cell reselection procedure may be based on a series of predictions and evaluation criteria, including but not limited to parameters such as signal quality, cell priority, and network configuration. For example, in a mobility scenario, the terminal device may perform signal quality measurements and, in conjunction with priority information provided by the network, select a cell with good signal quality that meets network requirements as the first target cell.

[0068] For example, the first process can be an RRC reconstruction process. Exemplarily, if the first condition is met, the first process can be the improved RRC reconstruction process proposed in this application. Alternatively, if the first condition is not met (such as if the second condition described below is met), the first process can be an RRC reconstruction process as defined in related technologies.

[0069] In step S320, if the first condition is met, the terminal device applies the configuration of the first target cell.

[0070] In some embodiments, when a first condition is met, the terminal device may apply the configuration of the first target cell. The configuration of the first target cell may refer to a series of parameters and settings that enable the terminal device to establish and maintain a communication link in the first target cell. For example, the configuration of the first target cell may include radio parameters, security parameters (such as keys), cell identifiers, network configurations, etc.

[0071] In the event of an RLF (Recurrent Link Failure) and / or cell handover failure, when the first condition is met, the terminal device can quickly switch from the current cell to the first target cell by applying the first target cell configuration, achieving rapid recovery of the communication link. This process reduces unnecessary signaling interactions, which not only reduces communication interruption time but also improves communication continuity and reliability, thereby optimizing user experience and network efficiency.

[0072] In some embodiments, the first condition may include: the first target cell is an LTM candidate cell, and the first ID associated with the first target cell is the same as the first ID associated with the source cell of the terminal device. The first ID may be used to identify the CU to which the cell belongs. If multiple cells have the same first ID, then the multiple cells may belong to the same CU. For example, the first ID may be an LTM No Security Change ID (LTM-NoSecurityChangeID).

[0073] In some embodiments, if the first target cell is an LTM candidate cell, and the first ID associated with the first target cell is the same as the first ID associated with the source cell of the terminal device, the terminal device can use the key of the source cell. As mentioned above, the fact that the first ID associated with the first target cell is the same as the first ID associated with the source cell of the terminal device indicates that the source cell and the first target cell belong to the same CU. In this case, the terminal device can assume that the first target cell and the source cell have the same security context. Therefore, in the event of an RLF and / or cell handover failure, the terminal device can directly apply the security configuration information of the source cell to perform the LTM procedure on the first target cell. It is understood that under this scheme, the terminal device does not need to perform a complex key update or reconfiguration process.

[0074] In some embodiments, the first condition may include: the terminal device receiving or preparing to receive a first parameter. Exemplarily, the first parameter is sent to the terminal device by the network device. Taking FIG4 as an example, FIG4 is a schematic flowchart of a wireless communication method according to an embodiment of this application. The method shown in FIG4 may include step S410.

[0075] In step S410, the network device may send the first parameter to the terminal device.

[0076] The first parameter can be used to generate the key corresponding to the first target cell. For example, the first parameter can be the NCC used for key updates.

[0077] In some implementations, when the terminal device receives the first parameter, it can directly apply the configuration of the first target cell to perform data transmission and reception.

[0078] In other implementations, the terminal device can apply the configuration of the first target cell before preparing to receive the first parameter, and then perform data transmission and reception upon receiving the first parameter. There can be various scenarios for preparing to receive the first parameter, and this application does not limit this. For example, when the terminal device selects the first target cell but does not have the corresponding key, the terminal device can prepare to receive the first parameter. Similarly, when the terminal device lacks key configuration information (e.g., NCC) for generating the key of the first target cell, the terminal device can prepare to receive the first parameter.

[0079] This application does not limit the form in which the first parameter is carried. In some embodiments, the first parameter may be carried in an RRC Reestablishment message. In other embodiments, the first parameter may be carried in other newly defined RRC messages. In still other embodiments, the first parameter may be carried in a MAC CE.

[0080] If the first parameter is not received, the terminal device may send a first request message. The first request message is used to request the network device to send the first parameter.

[0081] This application does not limit the format in which the first request information is carried. In some embodiments, the first request information may be carried in an RRC Reestablishment message. For example, the first request information may be carried in an RRC Reestablishment Request message. In some embodiments, the first request information may be carried in other newly defined RRC messages. In some embodiments, the first request information may be carried in a MAC CE.

[0082] Terminal devices can send first request information in a variety of situations.

[0083] In some embodiments, if the first ID associated with the first target cell is different from the first ID associated with the source cell of the terminal device, the terminal device may send a first request message. The difference between the first ID associated with the first target cell and the first ID associated with the source cell of the terminal device may indicate that the source cell and the first target cell belong to different CUs. For example, the terminal device may be attempting to access a first target cell that has a different network configuration or function than the source cell. In this case, the terminal device may send a first request message requesting the network device to send a first parameter indicating the key corresponding to the first target cell.

[0084] In some embodiments, if the source cell is not associated with a first ID, the terminal device may send a first request message. For example, if the source cell itself is not an LTM candidate cell, the source cell itself does not possess a first ID associated with LTM, thus resulting in the source cell not being associated with a first ID. In this case, the terminal device can request the first parameter by sending the first request message, thereby obtaining the key corresponding to the first target cell.

[0085] In some embodiments, if the terminal device is unable to generate the key corresponding to the first target cell, the terminal device may send a first request message. For example, if an LTM handover failure occurs between CUs, and the terminal device fails to receive the cell handover instruction due to a communication anomaly, it cannot obtain the NCC for key updates, and therefore cannot generate the key corresponding to the first target cell. In this case, the terminal device may send a first request message, requesting the network device to send a first parameter, and generate the key corresponding to the first target cell using the first parameter.

[0086] In some implementations, the first request information can also be used to indicate whether the terminal device has the configuration of the first target cell. In this case, the message used to indicate whether the terminal device has the configuration of the first target cell can be the same message as the information used to request the first parameter, i.e., the first request message. The terminal device can use the first request information to explicitly inform the network device whether it already has the relevant configuration information of the first target cell, thereby providing necessary context information for subsequent communication processes.

[0087] In some implementations, the message indicating whether the terminal device has the configuration of the first target cell and the message requesting the first parameter can be two separate messages. By sending these two different uplink messages, the terminal device can inform the network device whether it has the relevant configuration of the first target cell and request the first parameter from the network device.

[0088] Terminal devices can inform network devices whether they have a configuration for a first target cell. If the terminal device has a configuration for a first target cell, the network device does not need to send the configuration to the terminal device during subsequent fast failure recovery processes. For example, during RRC reconstruction, there is no need to redistribute the configuration for the first target cell. In this way, the RRC reconstruction process can be improved, unnecessary signaling interactions can be reduced, and resources can be saved.

[0089] In some embodiments, the first request information may include first information. This first information indicates whether the terminal device has a configuration for a first target cell. The configuration information for the first target cell may include radio resource configuration, security configuration (such as encryption keys, integrity protection algorithms, and security context information), cell identifier and network parameters, RRC configuration, etc. For example, the first information can be indicated through a first information field. The first information field can be used to directly indicate whether the terminal device has a configuration for the selected target cell. For example, when the first information field is a first value (e.g., 1), the terminal device has a configuration for the first target cell. When the first information field is a second value (e.g., 0), the terminal device does not have a configuration for the first target cell.

[0090] In some embodiments, the first request information may include second information. The second information indicates whether the first target cell is an LTM candidate cell. As described above, during the LTM preparation phase, the LTM configuration information (as described in step S220 above) already includes the configuration of LTM candidate cells; therefore, the second information can indirectly indicate whether the terminal device has a configuration for the first target cell. For example, if the first target cell is an LTM candidate cell, the terminal device has a configuration for the first target cell. If the first target cell is not an LTM candidate cell, the terminal device does not have a configuration for the first target cell.

[0091] In some embodiments, the first request information may include third information, wherein the third information is used to indicate the cell-radio network temporary identifier (C-RNTI) allocated to the terminal device by the first target cell. The C-RNTI is a temporary identifier allocated by the network to the terminal device to uniquely identify the terminal device within the cell and is used in processes such as radio resource allocation, scheduling, and paging. Since the allocation of the C-RNTI is usually related to the cell's configuration information, the third information can indirectly indicate whether the terminal device is configured with the first target cell. For example, if the first target cell has allocated a C-RNTI to the terminal device, the terminal device is configured with the first target cell. If the first target cell has not allocated a C-RNTI to the terminal device, the terminal device does not have configuration information for the first target cell.

[0092] In some embodiments, the first request information may be carried in one or more of the following messages: MAC CE, RRC. For example, the first information may be carried by an RRC message. Similarly, the second information may be carried by a MAC CE. And, the third information may be carried by an RRC message. The RRC message carrying the first information and the RRC message carrying the third information may be different.

[0093] For example, the uplink resource for sending the first request information may be a pre-configured uplink resource in the configuration of the first target cell. When the terminal device has a configuration of the first target cell, the terminal device includes pre-configured uplink resources. Therefore, the terminal device can use the pre-configured uplink resources provided in the configuration of the first target cell to send the first request information. For instance, when the terminal device has a configuration of the first target cell but no configuration for key updates, the terminal device can utilize the pre-configured uplink resources in the configuration of the first target cell to send the first request information.

[0094] For example, if the terminal device does not send the first request information, it can indirectly indicate that the terminal device has a current target cell (i.e., the first target cell) configuration by using the pre-configured uplink resources provided to the terminal device by the first target cell to transmit an RRC reconstruction message. If the terminal device does not have a first target cell configuration, it cannot use the pre-configured uplink resources to send an RRC reconstruction message.

[0095] It should be noted that any uplink signal or message sent by a terminal device to a network device can be referred to as the first uplink. For example, the first uplink can be the first uplink signal sent by the terminal device to the network device. Or, the first uplink can be the first request message sent by the terminal device to the network device.

[0096] In some embodiments, the first uplink may contain only the RRC rebuild message described above.

[0097] In some embodiments, the first uplink may include not only the RRC reconstruction message described above, but also other signaling, such as C-RNTI. Taking C-RNTI as an example, in some implementations, C-RNTI and the RRC reconstruction message can be transmitted in the same uplink message. When the network device receives this uplink message, it can not only obtain the RRC request information of the terminal device, but also identify the identity of the terminal device through C-RNTI, thereby optimizing the efficiency of the entire access process. In some implementations, C-RNTI and the RRC reconstruction message can also be transmitted in different uplink messages. In this case, the terminal device may first send an uplink message containing the RRC reconstruction message. Subsequently, the terminal device can carry C-RNTI in subsequent uplink messages.

[0098] In the above embodiments, this application does not limit the type of cell handover process. That is, the method described above can be used in the event of failure of any type of cell handover process. Exemplarily, the cell handover process may include at least one of the following: LTM process within a CU, LTM process between CUs, control plane-L1 / L2 triggered mobility (C-LTM) process within a CU, C-LTM process between CUs, handover process triggered by RRC signaling, conditional handover (CHO) process, SCG-based CHO process, and candidate SCG-based CHO process.

[0099] In some embodiments, the present application can be applied to LTM processes across CUs. Examples are provided below.

[0100] In cross-CU scenarios, the inter-CU LTM process can be triggered by a first message. This first message may include a second parameter, which can be used to generate the key corresponding to the first cell. The first cell may refer to the target cell in a failed cell handover process. The first condition may include one or more of the following four conditions.

[0101] Case 1: The first ID associated with the first target cell is the same as the first ID associated with the first cell.

[0102] Scenario 2: The first ID associated with the first target cell belongs to the first ID configuration, where the first ID configuration is used to configure the first ID.

[0103] Scenario 3: The first target cell is an LTM candidate cell.

[0104] Case 4: The first ID associated with the first target cell is different from the first ID associated with the source cell of the terminal device.

[0105] During the fast failure recovery process, if the first target cell selected by the terminal device meets the first condition, the terminal device can perform the LTM procedure to the first target cell.

[0106] This application does not limit the method of obtaining the first ID configuration. For example, the terminal device can obtain the first ID configuration by receiving a first message sent by the network device. Alternatively, the first ID configuration can be a configuration for the first ID of the source cell. Or, the first ID configuration can be a configuration for the first ID of an LTM candidate cell.

[0107] During the LTM process triggered between CUs via the first message, the terminal device can use the second parameter in the first message to generate a key for communication with the first target cell. The following section provides a detailed explanation of the four scenarios of the first condition described above.

[0108] In scenario 1, the first ID associated with the first target cell can be the same as the first ID associated with the first cell. In this case, the terminal device can quickly identify the association between the first target cell and the first cell. For example, the terminal device can generate a key for the first target cell using the second parameter corresponding to the first cell. Furthermore, during the access process to the first target cell, the terminal device can continue to use the first key corresponding to the first cell. This first key can be generated by the terminal device based on NCC during the LTM process to the first cell. This approach reduces fast failure recovery time and additional signaling interactions because it does not require new NCC information.

[0109] In scenario 2, the first ID associated with the first target cell belongs to the first ID configuration. The first ID configuration may contain at least one ID information, for example, it may include the first ID associated with the first target cell. Exemplarily, the first ID configuration may be directly included in the first message. The terminal device can quickly identify the first target cell through the first message and generate a key for communicating with the first target cell.

[0110] In scenario 3, the first target cell is an LTM candidate cell. In this embodiment, regardless of the association ID of the first target cell, as long as the first target cell is an LTM candidate cell, the terminal device can generate a key for the first target cell based on the second parameter. For example, the terminal device assumes that this second parameter can be used to generate keys for all other LTM candidate cells.

[0111] In scenario 4, the first ID of the first target cell is different from the first ID associated with the source cell of the terminal device. In this embodiment, considering that the terminal device may have already performed a key update during a failed cell handover, the terminal device may not be able to fall back to the source cell configuration. In this case, the terminal device cannot select a candidate cell with the same ID as the source cell, meaning the first ID of the first target cell is different from the first ID associated with the source cell of the terminal device. In this situation, the terminal device can generate the key for the first target cell based on the second parameter.

[0112] The first message may include an LTM handover command message. For example, the first message may include an LTM cell handover command, which can be carried by a MAC CE. Correspondingly, the second parameter may be the NCC in the cell handover command.

[0113] In some embodiments, the first target cell can be an LTM candidate cell, as described in detail above. In other embodiments, the first target cell can also be a CHO candidate target cell. For ease of understanding, conditional handover will be explained below.

[0114] The main goal of conditional handover is to improve the reliability and robustness of user handover, and to solve the problem of handover being too late due to excessive handover preparation time, or handover failure caused by a sharp decline in the source cell channel quality during the handover process.

[0115] The core idea of ​​conditional handover is to pre-configure the handover command content to the terminal device. Specifically, the network device (source base station) corresponding to the source cell can prepare one or more candidate target cells in advance. These candidate target cells are sent to the terminal device before the radio signal quality of the source cell deteriorates. The terminal device can measure the one or more candidate target cells. After receiving the conditional handover configuration, the terminal device can determine whether the candidate target cells meet the handover requirements based on the measurement results. When one of the candidate target cells meets the handover requirements, the terminal device can autonomously execute the configuration in the handover command and directly initiate access to the qualified target cell.

[0116] Since the terminal device no longer triggers measurement reporting when the handover conditions are met, and the terminal device has already obtained the configuration in the handover command, the previously mentioned problem of measurement reporting and handover commands not being received correctly is solved. Especially in high-speed mobile scenarios or scenarios where signals rapidly fade during handover, conditional handover can greatly improve the handover success rate. Furthermore, since the actual handover is determined by the terminal device based on the target cell's radio channel conditions, the timing of handover in conditional handover can be better matched with the terminal device's radio quality.

[0117] A conditional handover candidate cell (also known as a CHO candidate cell) refers to the target cell selected by the terminal device in a CHO scenario based on conditions and measurement results provided by the network device. In some embodiments, the conditional handover process may include conditional handover with a secondary cell group (CHO with SCG). In some embodiments, the conditional handover process may include conditional handover with a candidate secondary cell group (CHO with candidate SCG).

[0118] Because the CHO mechanism allows the network device corresponding to the source cell to send the configuration information of the candidate target cell for conditional handover to the terminal device in advance when the communication quality is good, and can directly use the pre-configured information to switch to the target cell when the handover trigger condition is met, without waiting for further instructions from the network device, the terminal device can use the candidate target cell for conditional handover as the first target cell.

[0119] In some embodiments, the first condition may include that the LTM candidate cell is configured to be allowed to be selected as the first target cell. For example, the first condition may include that the LTM candidate cell is configured to be allowed for fast failure recovery. Only if allowed will the terminal device select the LTM candidate cell and further determine whether it can be used as the first target cell.

[0120] In some embodiments, the first condition may include a handover candidate cell being configured to be allowed to be selected as the first target cell. For example, the first condition may include a handover candidate cell being configured to be allowed for fast failure recovery. Only if allowed will the terminal device select the handover candidate cell and further determine whether it can be used as the first target cell.

[0121] In some embodiments, the first condition may further include a failed cell handover process and a limitation on the candidate cell type for fast failure recovery, which will be described in detail below.

[0122] Scenario 1: The first condition may not limit the failed cell handover process or the candidate cell type used for fast failure recovery. For example, the failed cell handover process can be of any type. For instance, a failed handover process may include at least one of the following: an intra-CU LTM process, an inter-CU LTM process, an intra-CU C-LTM process, an inter-CU C-LTM process, an RRC signaling-triggered handover process, a CHO process, an SCG-based CHO process, or a candidate SCG-based CHO process. Correspondingly, the candidate cell selected for failure recovery can also be of any type. For example, the candidate cell selected for failure recovery can be an LTM candidate cell or a conditional handover candidate target cell.

[0123] Scenario 2: The first condition may include: if the failed cell handover process is an LTM process within a CU, or if there is no information for generating the key corresponding to the first target cell, the terminal device can only select an LTM candidate cell or a conditional handover candidate target cell within the CU for fast failure recovery, and cannot select an LTM candidate cell between CUs. For example, if the terminal device has never received a cell handover command containing NCC information, in this case, the terminal device does not have the information for generating the key corresponding to the first target cell.

[0124] Scenario 3: The first condition may include: if the failed cell handover process is an inter-CU LTM process, or if information for generating the key corresponding to the first target cell exists, the terminal device can only select an inter-CU LTM candidate cell or a conditional handover candidate target cell for fast failure recovery. For example, during an inter-CU LTM process, the terminal device may receive a cell handover command from the network device, which may include NCC information for key updates during cell handover. However, if a subsequent handover process fails, resulting in an unsuccessful cell handover, the terminal device may still retain the NCC information for key updates. In this case, the terminal device possesses information for generating the key corresponding to the first target cell.

[0125] In some embodiments, when the cell handover process includes an LTM handover process, the first target cell selected by the terminal device needs to be an LTM candidate cell. For example, the LTM handover process may include at least one of the following: an LTM process within a CU, an LTM process between CUs, a C-LTM process within a CU, and a C-LTM process between CUs.

[0126] In some embodiments, where the cell handover process includes a conditional handover process, the first target cell selected by the terminal device needs to belong to a conditional handover candidate target cell. For example, the conditional handover process may include at least one of the following: a CHO process, an SCG-based CHO process, or a candidate SCG-based CHO process.

[0127] In some implementations, the behavior of the terminal device can be determined by a second condition. For example, if the second condition is met, the terminal device may not apply the configuration of the first target cell, and the terminal device may release the LTM candidate cell configuration, and / or conditionally switch the candidate target cell configuration.

[0128] For example, the second condition may include the terminal device not having a key corresponding to the first target cell.

[0129] For example, the second condition may include: the first target cell is not an LTM candidate cell and / or a conditional handover candidate target cell.

[0130] For example, the second condition may include: the first target cell belongs to an LTM candidate cell, and the first target cell is a cross-CU cell of the terminal device's source cell. For instance, in an LTM handover between CUs, since the first target cell and the source cell belong to different CUs, the key needs to be updated. If the key cannot be updated successfully or there is a security risk, the network device may instruct the terminal device to release the current LTM candidate cell configuration.

[0131] Before the terminal device selects the first target cell, or when the cell handover process fails, the terminal device can restore the configuration of the source cell of the application terminal device.

[0132] For example, in the event of a key update during cell handover, the terminal device can restore the configuration of the source cell, including Packet Data Convergence Protocol (PDCP) state variables. This key-updated handover process can be an inter-CU LTM process, a CHO process, or a handover triggered by RRC signaling. In this case, the terminal device has already received the new key and may have already attempted to use this information for handover. If the handover fails, the terminal device needs to restore the configuration of the source cell to ensure the security and continuity of communication. Meanwhile, the PDCP state variables are protocol state information maintained by the terminal device in the source cell, which may include sequence numbers, encryption states, etc., and this information is crucial for restoring communication. Restoring the PDCP state variables ensures that after a handover failure, the terminal device and the source cell can resynchronize from the same starting point, avoiding packet loss or out-of-order delivery due to key inconsistencies.

[0133] Key updates during cell handover can manifest in several ways. For example, a key update could occur during a failed handover, in the first target cell where a key update configuration is included, or in the LTM cell handover command where an NCC (Neural Control Code) is included to generate the key corresponding to the first target cell.

[0134] For example, in the absence of a key update during cell handover, the terminal device can restore the configuration of the source cell, excluding PDCP state variables. This cell handover process without a key update can be an inter-CU LTM process, a CHO process, or a handover process triggered by RRC signaling. In this case, the terminal device can restore the configuration of the source cell, but without PDCP state variables. Since the terminal device has not received any new key related to the first target cell, it is not necessary to restore the PDCP state variables when restoring the source cell configuration, thus maintaining the continuity of data transmission.

[0135] There are several ways in which a key update is not performed during a cell handover process. For example, it could be that a key update was not performed during a failed handover, the first target cell does not contain a key update configuration, or the LTM cell handover command does not contain an NCC used to generate the key corresponding to the first target cell.

[0136] For ease of understanding, the present application will be illustrated below with examples 1 to 5.

[0137] Example 1

[0138] In Example 1, the first target cell is an LTM candidate cell, and the terminal device is a UE. The UE does not have an NCC for deriving the key of the first target cell. For example, the UE has never received a cell handover command containing NCC information. In this case, the UE does not have an NCC for deriving the key corresponding to the first target cell.

[0139] When a Recurrent Leak (RLF) occurs, and / or the cell handover process fails (e.g., a T304 timeout, where T304 is a timer associated with the cell handover process), the UE initiates a first procedure. For example, the first procedure can be an RRC reconstruction procedure. The cell handover procedure can include at least one of the following: an intra-CU LTM procedure, an inter-CU LTM procedure, an intra-CU C-LTM procedure, an inter-CU C-LTM procedure, an RRC signaling-triggered handover procedure, a CHO procedure, an SCG-based CHO procedure, or a candidate SCG-based CHO procedure.

[0140] The following section uses the RRC reconstruction process as an example to provide a detailed explanation.

[0141] During RRC reconstruction, the UE performs cell reselection.

[0142] If an LTM candidate cell is configured not to be used for fast failure recovery, the UE releases that LTM candidate cell configuration. For example, if no LTM-Switch attempt is configured, the UE releases that LTM candidate cell configuration.

[0143] If the LTM candidate cell is configured to be allowed for fast failure recovery, for example, if attemptLTM-Switch is configured, the UE can proceed to the next step based on whether the ID associated with the LTM candidate cell is the same as the ID associated with the source cell.

[0144] For example, if the first target cell selected is an LTM candidate cell, and the ID associated with the LTM candidate cell is the same as the ID associated with the source cell, then the UE can use the key of the source cell to perform the LTM procedure on the selected LTM candidate cell.

[0145] For example, if the first target cell selected is an LTM candidate cell, but the ID associated with the LTM candidate cell is different from the ID associated with the source cell, then the UE can send a first request message to request the network device to send the first key parameter corresponding to the LTM candidate cell.

[0146] During the RRC reconstruction process, the first request message can be referred to as the first RRC message. For example, the first RRC message can be an RRCReestablishmentRequest message, or other newly defined RRC messages.

[0147] In implementation method 1, if the first target cell is an LTM candidate cell and is a cross-CU cell of the UE's source cell, the key needs to be updated because the first target cell and the source cell belong to different CUs. However, the UE does not have an NCC for deriving the key of the first target cell. In this case, the UE releases the configuration of the current LTM candidate cell (i.e., the first target cell).

[0148] In implementation method 2, the UE can first apply the first target cell configuration, but will not perform data transmission or reception until it receives feedback from the network device regarding the first RRC message. The feedback from the network device regarding the first RRC message can be referred to as the second RRC message. The second RRC message includes a first parameter, which can be, for example, an NCC used for key updates.

[0149] In implementation method 3, the UE can apply the first target cell configuration after receiving the second RRC message.

[0150] The second RRC message mentioned above can be an RRCReestablishment message or other newly defined RRC messages.

[0151] For implementation methods 2 and 3, the UE needs to inform the network device whether it has the configuration of the current cell (i.e. the first target cell) to help the network device determine whether it needs to carry the configuration of the first target cell through the second RRC message.

[0152] For example, the UE may include a first indication in the first RRC message, the first indication being used to indicate whether a current cell configuration exists, and / or whether the current cell is an LTM candidate cell.

[0153] For example, the UE may include the C-RNTI assigned to the UE by the first target cell in the first uplink sent to the network.

[0154] For example, the UE can send the first uplink using the pre-configured uplink resources provided in the first target cell configuration.

[0155] In one implementation, regardless of the handover type of the cell handover process, fast failure recovery can be performed in accordance with the method provided in Example 1 when a handover failure occurs.

[0156] In one implementation, fast failure recovery can only be performed as provided in Example 1 when the cell handover process is an LTM within a CU. That is, if the first process is triggered by a cell handover failure, and the cell handover process is any one or more of the following: an LTM process between CUs, a cell handover triggered by RRC signaling, a CHO process, a CHO process based on an SCG, or a CHO process based on a candidate SCG, the UE's behavior also includes: releasing the LTM candidate cell configuration.

[0157] Example 2

[0158] In Example 2, the first target cell is an LTM candidate cell, the terminal device is a UE, and the UE has an NCC used to derive the key of the first target cell. For example, during the LTM process between CUs, the UE has received a cell handover command sent by the network device, which includes an NCC for key updates during cell handover. However, if the subsequent handover process fails, resulting in an unsuccessful cell handover, the UE still has an NCC used to derive the key of the first target cell. The NCC in the LTM cell handover command can be used for some / all LTM candidate cells between CUs.

[0159] When a UE experiences an RLF (Recurrent Leak) and / or a cell handover procedure failure (such as a T304 timeout), it initiates a first procedure. For example, the first procedure can be an RRC (Reconstruction and Reconstruction Control) procedure. The cell handover procedure can include at least one of the following: an intra-CU LTM (Large-Time Measuring) procedure, an inter-CU LTM procedure, an intra-CU C-LTM procedure, an inter-CU C-LTM procedure, an RRC signaling-triggered handover procedure, a CHO (Choice of Interest) procedure, an SCG-based CHO procedure, or a candidate SCG-based CHO procedure.

[0160] The following section uses the RRC reconstruction process as an example to provide a detailed explanation.

[0161] During RRC reconstruction, the UE performs cell reselection.

[0162] If an LTM candidate cell is configured not to be used for fast failure recovery, the UE releases that LTM candidate cell configuration. For example, if attemptLTM-Switch is not configured, the UE releases that LTM candidate cell configuration.

[0163] If the LTM candidate cell is configured to be allowed for fast failure recovery, for example, if attemptLTM-Switch is configured, the UE can proceed to the next step using the following four options.

[0164] Option 1: If the first target cell selected by the UE is an LTM candidate cell, and the ID associated with the LTM candidate cell is the same as the ID associated with the source cell or the first cell, then the UE performs the LTM procedure on the selected LTM candidate cell. Here, the first cell can refer to the target cell in a failed cell handover process.

[0165] Option 2: If the target cell selected by the UE is an LTM candidate cell, and the ID associated with the LTM candidate cell is the same as the ID associated with the source cell or the first cell, or the ID associated with the candidate cell belongs to the first ID configuration, then the UE performs the LTM procedure on the selected LTM candidate cell.

[0166] Option 3: If the target cell selected by the UE is an LTM candidate cell, the UE performs the LTM procedure on the selected LTM candidate cell.

[0167] Option 4: For options 1-3 above, considering that the UE may have performed a key update during a failed cell handover, the UE may not be able to fall back to the source cell configuration. Therefore, the UE cannot select a candidate cell with the same ID as the source cell.

[0168] For the above four options, the UE's behavior also includes:

[0169] If the ID associated with the selected LTM candidate cell is the same as the ID associated with the source cell, the UE continues to use the source cell key in the first target cell. For example, the UE restores the source cell configuration.

[0170] If the ID associated with the selected LTM candidate cell is the same as the ID associated with the first cell, the UE generates a key for the first target cell based on the NCC in the LTM cell switch command MAC CE; or, the UE continues to use the first key. The LTM cell switch command MAC CE instructs the UE to initiate an LTM procedure towards the first cell, and the UE generates the first key based on the NCC during the LTM initiation process.

[0171] If the ID associated with the selected LTM candidate cell is different from the IDs associated with the source cell and the first cell, the UE generates the key for the first target cell based on the NCC in the LTM cell switch command MAC CE.

[0172] In Example 2, the NCC used to generate the first target cell key comes from the LTM cell switch command MAC CE. In one implementation, the UE defaults to allowing the NCC to be used to generate keys for all other LTM candidate cells, i.e., option 3; or the UE defaults to allowing the NCC to be used to generate keys for other candidate cells belonging to the same CU as the first cell. In another implementation, the UE can determine which CUs / candidate cells the NCC can be used to generate keys for through the LTM cell switch command MAC CE.

[0173] In one implementation, fast failure recovery can only be performed in the manner provided in Example 2 if the failed cell handover process is an inter-CU LTM process.

[0174] Example 3

[0175] In Example 3, the terminal device is a UE. After the cell handover process fails, the UE can also select other types of candidate cells to perform fast failure recovery, such as the first target cell being a CHO candidate cell.

[0176] When a cell handover process fails (e.g., T304 timeout), the UE initiates a first procedure. For example, the first procedure can be an RRC reconstruction procedure. The cell handover procedure can include at least one of the following: an intra-CU LTM procedure, an inter-CU LTM procedure, an intra-CU C-LTM procedure, or an inter-CU C-LTM procedure.

[0177] The following section uses the RRC reconstruction process as an example to provide a detailed explanation.

[0178] During RRC reconstruction, the UE performs cell reselection.

[0179] If the CHO candidate cell is configured to be used for fast failure recovery, such as by configuring attemptCondReconfig, the UE's behavior further includes: if the selected first target cell is a CHO candidate cell, then the UE applies the configuration of the candidate cell and performs other CHO execution-related behaviors.

[0180] Example 4

[0181] Example 4 provides a fast failure recovery scenario applicable to LTM candidate cells and CHO candidate cells.

[0182] In one implementation, LTM candidate cells can only be used for RLF and fast failure recovery after LTM failure. For example, LTM failure can include at least one of the following: LTM process failure within a CU, LTM process failure between CUs, C-LTM process failure within a CU, and C-LTM process failure between CUs.

[0183] In another implementation, LTM candidate cells can be used for RLF and fast failure recovery after various types of cell handover process failures. For example, cell handover processes can include at least one of the following: intra-CU LTM process, inter-CU LTM process, intra-CU C-LTM process, inter-CU C-LTM process, RRC signaling triggered handover process, CHO process, SCG-based CHO process, and candidate SCG-based CHO process.

[0184] In one implementation, the CHO candidate cell can only be used for RLF and fast failure recovery after CHO failure. For example, LTM failure can include at least one of the following: CHO process failure, SCG-based CHO process failure, and candidate SCG-based CHO process failure.

[0185] In another implementation, the CHO candidate cell can be used for RLF and fast failure recovery after various types of cell handover process failures. For example, the cell handover process may include at least one of the following: LTM process within a CU, LTM process between CUs, C-LTM process within a CU, C-LTM process between CUs, handover process triggered by RRC signaling, CHO process, SCG-based CHO process, and CHO process based on candidate SCG.

[0186] According to Examples 1-3, if the target cell selected by the UE is not an LTM candidate cell and / or a CHO candidate cell, the UE's actions include: releasing the LTM candidate configuration, and / or releasing the CHO candidate configuration, and / or sending an RRCReestablishmentRequest to the network.

[0187] Example 5

[0188] In Example 5, the terminal device is a UE. When a cell handover process fails, the UE's behavior includes:

[0189] If a failed handover procedure performed a key update, or if the first target cell contains a key update configuration, or if the LTM cell switch command contains an NCC, the UE reverts back to the source cell configuration, including the PDCP state variables.

[0190] If the failed handover process did not perform a key update, or if the first target cell does not contain a key update configuration, or if the LTM cell switch command does not contain an NCC, and if attemptLTM-Switch is configured, the UE reverts back to the source cell configuration except for the PDCP state variables.

[0191] The method embodiments of this application have been described in detail above with reference to Figures 1 to 4. The apparatus embodiments of this application will be described in detail below with reference to Figures 5 to 7. It should be understood that the descriptions of the method embodiments correspond to the descriptions of the apparatus embodiments; therefore, any parts not described in detail can be referred to the preceding method embodiments.

[0192] Figure 5 is a schematic structural diagram of a terminal device 500 provided in an embodiment of this application. The terminal device 500 shown in Figure 5 includes a selection unit 510 and an application unit 520.

[0193] Selection unit 510 is used to select a first target cell in the event of an RLF and / or cell handover failure.

[0194] Application unit 520 is used to apply the configuration of the first target cell when the first condition is met.

[0195] In some implementations, the first condition includes: the first target cell is an LTM candidate cell, and the first ID associated with the first target cell is the same as the first ID associated with the source cell of the terminal device.

[0196] In some implementations, the terminal device is also used to use the key of the source cell.

[0197] In some implementations, the first condition includes: the terminal device receiving or preparing to receive a first parameter, the first parameter being used to generate a key corresponding to the first target cell.

[0198] In some implementations, the first parameter is carried in an RRCReestablishment message or a MAC CE.

[0199] In some implementations, the terminal device is further configured to send first request information; wherein the first request information is used to request the sending of the first parameter.

[0200] In some implementations, the first request information is carried in an RRCReestablishmentRequest message or a MAC CE.

[0201] In some implementations, sending the first request information includes one or more of the following:

[0202] If the first ID associated with the first target cell is different from the first ID associated with the source cell of the terminal device, the first request information is sent.

[0203] If the source cell is not associated with the first ID, send the first request information;

[0204] If the terminal device is unable to generate the key corresponding to the first target cell, the first request information is sent.

[0205] In some implementations, the first request information is also used to indicate whether the terminal device has the configuration of the first target cell.

[0206] In some implementations, the first request information includes one or more of the following:

[0207] The first piece of information is used to indicate whether the terminal device is configured with the first target cell;

[0208] The second piece of information is used to indicate whether the first target cell is an LTM candidate cell;

[0209] The third piece of information is used to indicate the C-RNTI allocated by the first target cell to the terminal device.

[0210] In some implementations, the cell handover process includes a cross-CU LTM process, which is triggered by a first message. The first message includes a second parameter used to generate a key corresponding to the first cell. The first condition includes one or more of the following:

[0211] The first ID associated with the first target cell is the same as the first ID associated with the first cell;

[0212] The first ID associated with the first target cell belongs to the first ID configuration;

[0213] The first target cell is an LTM candidate cell;

[0214] The first ID associated with the first target cell is different from the first ID associated with the source cell of the terminal device.

[0215] In some implementations, the first ID configuration is obtained through one or more of the following: the first message, the configuration for the source cell, and the configuration for the LTM candidate cell.

[0216] In some implementations, the terminal device is also used to generate a key for communicating with the first target cell using the second parameter.

[0217] In some implementations, the first message includes an LTM switching command message.

[0218] In some implementations, the first target cell is an LTM candidate cell, or a conditional handover candidate target cell.

[0219] In some implementations, the first condition includes:

[0220] The LTM candidate cell is configured to be allowed to be selected as the first target cell; and / or,

[0221] The candidate target cell for conditional handover is configured to be allowed to be selected as the first target cell.

[0222] In some implementations, where the cell handover process includes an LTM handover process, the first target cell selected by the terminal device needs to belong to the LTM candidate cell.

[0223] In some implementations, where the cell handover process includes a conditional handover process, the first target cell selected by the terminal device needs to belong to the conditional handover candidate target cell.

[0224] In some implementations, if the second condition is met, the terminal device does not apply the configuration of the first target cell, and the terminal device releases the LTM candidate cell configuration and / or the conditional handover candidate target cell configuration.

[0225] In some implementations, the second condition includes one or more of the following:

[0226] The terminal device does not have the key corresponding to the first target cell;

[0227] The first target cell is not an LTM candidate cell or a conditional handover candidate target cell;

[0228] If the first target cell belongs to the LTM candidate cell and the first target cell is a cross-CU cell of the source cell of the terminal device.

[0229] In some implementations, before the terminal device selects the first target cell or when the cell handover process fails, the terminal device restores the configuration of the source cell of the terminal device.

[0230] In some implementations, when a key update occurs during the cell handover process, the configuration of the source cell for which the terminal device resumes the application includes PDCP state variables; and / or, when no key update occurs during the cell handover process, the configuration of the source cell for which the terminal device resumes the application does not include PDCP state variables.

[0231] In some implementations, the cell handover process includes at least one of the following: LTM process within a CU, LTM process between CUs, C-LTM process within a CU, C-LTM process between CUs, handover process triggered by RRC signaling, CHO process, CHO process based on SCG, and CHO process based on candidate SCG.

[0232] In an optional embodiment, the selection unit 510 and the application unit 520 may be a processor 710. The terminal device 500 may also include a memory 720 and a transceiver 730, as shown in FIG7.

[0233] Figure 6 is a schematic diagram of a network device according to an embodiment of this application. The network device 600 shown in Figure 6 includes a transmitting unit 610.

[0234] The sending unit 610 is used to send a first parameter to the terminal device; wherein the first parameter is used to generate a key corresponding to a first target cell, and the first target cell is the cell selected by the terminal device in the event of an RLF and / or cell handover failure.

[0235] In some implementations, the first parameter is carried in an RRCReestablishment message or a MAC CE.

[0236] In some implementations, the network device is further configured to receive first request information sent by the terminal device; wherein the first request information is used to request the sending of the first parameter.

[0237] In some implementations, the first request information is carried in an RRCReestablishmentRequest message or a MAC CE.

[0238] In some implementations, the first request information is also used to indicate whether the terminal device has the configuration of the first target cell.

[0239] In some implementations, the first request information includes one or more of the following:

[0240] The first piece of information is used to indicate whether the terminal device is configured with the first target cell;

[0241] The second piece of information is used to indicate whether the first target cell is an LTM candidate cell;

[0242] The third piece of information is used to indicate the C-RNTI allocated by the first target cell to the terminal device.

[0243] In an optional embodiment, the transmitting unit 610 may be a transceiver 730. The network device 600 may also include a processor 710 and a memory 720, as shown in FIG7.

[0244] Figure 7 is a schematic structural diagram of a communication device according to an embodiment of this application. The dashed lines in Figure 7 indicate that the unit or module is optional. This device 700 can be used to implement the methods described in the above method embodiments. Device 700 can be a chip, a terminal device, or a network device.

[0245] The apparatus 700 may include one or more processors 710. The processor 710 may support the apparatus 700 in implementing the methods described in the preceding method embodiments. The processor 710 may be a general-purpose processor or a special-purpose processor. For example, the processor may be a central processing unit (CPU). Alternatively, the processor may be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor.

[0246] The apparatus 700 may also include one or more memories 720. The memories 720 store a program that can be executed by the processor 710, causing the processor 710 to perform the methods described in the preceding method embodiments. The memories 720 may be independent of the processor 710 or integrated into the processor 710.

[0247] The device 700 may also include a transceiver 730. The processor 710 can communicate with other devices or chips via the transceiver 730. For example, the processor 710 can send and receive data with other devices or chips via the transceiver 730.

[0248] This application also provides a computer-readable storage medium for storing a program. This computer-readable storage medium can be applied to a terminal or network device provided in this application, and the program causes a computer to execute the methods performed by the terminal or network device in various embodiments of this application.

[0249] This application also provides a computer program product. The computer program product includes a program. The computer program product can be applied to a terminal or network device provided in this application embodiment, and the program causes a computer to execute the methods performed by the terminal or network device in various embodiments of this application.

[0250] This application also provides a computer program. This computer program can be applied to the terminal or network device provided in this application, and the computer program causes the computer to execute the methods performed by the terminal or network device in various embodiments of this application.

[0251] It should be understood that the terms "system" and "network" in this application can be used interchangeably. Furthermore, the terminology used in this application is only for explaining specific embodiments of the application and is not intended to limit the application. The terms "first," "second," "third," and "fourth," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish different objects, not to describe a specific order. In addition, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion.

[0252] In the embodiments of this application, the term "instruction" can be a direct instruction, an indirect instruction, or an indication of a relationship. For example, A instructing B can mean that A directly instructs B, such as B being able to obtain information through A; it can also mean that A indirectly instructs B, such as A instructing C, so B can obtain information through C; or it can mean that there is a relationship between A and B.

[0253] In the embodiments of this application, "B corresponding to A" means that B is associated with A, and B can be determined based on A. However, it should also be understood that determining B based on A does not mean that B is determined solely based on A; B can also be determined based on A and / or other information.

[0254] In the embodiments of this application, the term "correspondence" can indicate a direct or indirect correspondence between two things, or an association between two things, or a relationship such as instruction and being instructed, configuration and being configured.

[0255] In this application embodiment, "predefined" or "preconfigured" can be implemented by pre-storing corresponding codes, tables, or other means that can be used to indicate relevant information in the device (e.g., including terminal devices and network devices). This application does not limit the specific implementation method. For example, predefined can refer to what is defined in the protocol.

[0256] In this application embodiment, the "protocol" may refer to a standard protocol in the field of communication, such as the LTE protocol, the NR protocol, and related protocols applied to future communication systems. This application does not limit this.

[0257] In the embodiments of this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0258] In the various embodiments of this application, the order of the above-mentioned processes does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0259] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0260] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0261] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0262] In the above embodiments, implementation can be achieved entirely or partially through software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented entirely or partially in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can read or a data storage device such as a server or data center that integrates one or more available media. The available media may be magnetic media (e.g., floppy disks, hard disks, magnetic tapes), optical media (e.g., digital video discs, DVDs) or semiconductor media (e.g., solid-state disks, SSDs), etc.

[0263] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A wireless communication method, characterized in that, include: In the event of a radio link failure (RLF) and / or a cell handover failure, the terminal device selects the first target cell. as well as, If the first condition is met, the terminal device applies the configuration of the first target cell.

2. The method according to claim 1, characterized in that, The first condition includes: the first target cell is a mobility LTM candidate cell triggered by layer 1 / layer 2, and the first ID associated with the first target cell is the same as the first ID associated with the source cell of the terminal device.

3. The method according to claim 2, characterized in that, The method further includes: the terminal device using the key of the source cell.

4. The method according to claim 1, characterized in that, The first condition includes: the terminal device receiving or preparing to receive a first parameter, the first parameter being used to generate a key corresponding to the first target cell.

5. The method according to claim 4, characterized in that, The first parameter is carried in the RRC Reestablishment message or in the Media Access Control Unit (MAC CE).

6. The method according to claim 4 or 5, characterized in that, The method further includes: The terminal device sends a first request message; The first request information is used to request the sending of the first parameter.

7. The method according to claim 6, characterized in that, The first request information is carried in the RRC Reestablishment Request message or in the MAC CE.

8. The method according to claim 6 or 7, characterized in that, The terminal device sends a first request message including one or more of the following: If the first ID associated with the first target cell is different from the first ID associated with the source cell of the terminal device, the terminal device sends the first request information; If the source cell is not associated with the first ID, the terminal device sends the first request information; If the terminal device is unable to generate the key corresponding to the first target cell, the terminal device sends the first request information.

9. The method according to any one of claims 6-8, characterized in that, The first request information is also used to indicate whether the terminal device is configured with the first target cell.

10. The method according to claim 9, characterized in that, The first request information includes one or more of the following: The first piece of information is used to indicate whether the terminal device is configured with the first target cell; The second piece of information is used to indicate whether the first target cell is an LTM candidate cell; The third piece of information is used to indicate the Cell Radio Network Temporary Identifier (C-RNTI) allocated by the first target cell to the terminal device.

11. The method according to any one of claims 1-10, characterized in that, The cell handover process includes a cross-CU LTM process, which is triggered by a first message. The first message includes a second parameter, which is used to generate the key corresponding to the first cell. The first condition includes one or more of the following: The first ID associated with the first target cell is the same as the first ID associated with the first cell; The first ID associated with the first target cell belongs to the first ID configuration; The first target cell is an LTM candidate cell; The first ID associated with the first target cell is different from the first ID associated with the source cell of the terminal device.

12. The method according to claim 11, characterized in that, The first ID configuration is obtained through one or more of the following: the first message, the configuration for the source cell, and the configuration for the LTM candidate cell.

13. The method according to claim 11 or 12, characterized in that, The method further includes: The terminal device uses the second parameter to generate a key for communicating with the first target cell.

14. The method according to any one of claims 11-13, characterized in that, The first message includes an LTM switching command message.

15. The method according to any one of claims 1-14, characterized in that, The first target cell belongs to the LTM candidate cell, or the conditional handover candidate target cell.

16. The method according to claim 15, characterized in that, The first condition includes: The LTM candidate cell is configured to be allowed to be selected as the first target cell; and / or, The candidate target cell for conditional handover is configured to be allowed to be selected as the first target cell.

17. The method according to claim 15 or 16, characterized in that, When the cell handover process includes an LTM handover process, the first target cell selected by the terminal device needs to belong to the LTM candidate cell.

18. The method according to any one of claims 15-17, characterized in that, When the cell handover process includes a conditional handover process, the first target cell selected by the terminal device needs to belong to the conditional handover candidate target cell.

19. The method according to any one of claims 15-17, characterized in that, The method further includes: when a second condition is met, the terminal device does not apply the configuration of the first target cell, and the terminal device releases the LTM candidate cell configuration and / or the conditional handover candidate target cell configuration.

20. The method according to claim 19, characterized in that, The second condition includes one or more of the following: The terminal device does not have the key corresponding to the first target cell; The first target cell is not an LTM candidate cell or a conditional handover candidate target cell; If the first target cell belongs to the LTM candidate cell and the first target cell is a cross-CU cell of the source cell of the terminal device.

21. The method according to any one of claims 1-20, characterized in that, When the terminal device selects the first target cell or when the cell handover process fails, the method further includes: The terminal device restores the configuration of the source cell of the terminal device.

22. The method according to claim 21, characterized in that, In the event of a key update during the cell handover process, the configuration of the source cell for which the terminal device resumes application includes PDCP status variables; And / or, If there is no key update during the cell handover process, the configuration of the source cell for which the terminal device resumes application does not include PDCP state variables.

23. The method according to any one of claims 1-22, characterized in that, The cell handover process includes at least one of the following: LTM process within a CU, LTM process between CUs, mobility C-LTM process triggered by control plane-layer 1 / layer 2 within a CU, C-LTM process between CUs, handover process triggered by RRC signaling, conditional handover CHO process, SCG-based CHO process, and candidate SCG-based CHO process.

24. A wireless communication method, characterized in that, include: The network device sends the first parameter to the terminal device; The first parameter is used to generate the key corresponding to the first target cell, which is the cell selected by the terminal device in the event of an RLF and / or cell handover failure.

25. The method according to claim 24, characterized in that, The first parameter is carried in the RRCReestablishment message or in the MAC CE.

26. The method according to claim 24 or 25, characterized in that, The method further includes: The network device receives the first request information sent by the terminal device; The first request information is used to request the sending of the first parameter.

27. The method according to claim 26, characterized in that, The first request information is carried in the RRCReestablishmentRequest message or in MAC CE.

28. The method according to claim 26 or 27, characterized in that, The first request information is also used to indicate whether the terminal device is configured with the first target cell.

29. The method according to claim 28, characterized in that, The first request information includes one or more of the following: The first piece of information is used to indicate whether the terminal device is configured with the first target cell; The second piece of information is used to indicate whether the first target cell is an LTM candidate cell; The third piece of information is used to indicate the C-RNTI allocated by the first target cell to the terminal device.

30. A terminal device, characterized in that, include: The selection unit is used to select the first target cell in the event of an RLF and / or cell handover failure. as well as, An application unit is used to apply the configuration of the first target cell when a first condition is met.

31. The terminal device according to claim 30, characterized in that, The first condition includes: the first target cell is an LTM candidate cell, and the first ID associated with the first target cell is the same as the first ID associated with the source cell of the terminal device.

32. The terminal device according to claim 31, characterized in that, The terminal device is also used to use the key of the source cell.

33. The terminal device according to claim 30, characterized in that, The first condition includes: the terminal device receiving or preparing to receive a first parameter, the first parameter being used to generate a key corresponding to the first target cell.

34. The terminal device according to claim 33, characterized in that, The first parameter is carried in the RRCReestablishment message or in the MAC CE.

35. The terminal device according to claim 33 or 34, characterized in that, The terminal device is also used to send first request information; The first request information is used to request the sending of the first parameter.

36. The terminal device according to claim 35, characterized in that, The first request information is carried in the RRCReestablishmentRequest message or in MAC CE.

37. The terminal device according to claim 35 or 36, characterized in that, The sending of the first request information includes one or more of the following: If the first ID associated with the first target cell is different from the first ID associated with the source cell of the terminal device, the first request information is sent. If the source cell is not associated with the first ID, send the first request information; If the terminal device is unable to generate the key corresponding to the first target cell, the first request information is sent.

38. The terminal device according to any one of claims 35-37, characterized in that, The first request information is also used to indicate whether the terminal device is configured with the first target cell.

39. The terminal device according to claim 38, characterized in that, The first request information includes one or more of the following: The first piece of information is used to indicate whether the terminal device is configured with the first target cell; The second piece of information is used to indicate whether the first target cell is an LTM candidate cell; The third piece of information is used to indicate the C-RNTI allocated by the first target cell to the terminal device.

40. The terminal device according to any one of claims 30-39, characterized in that, The cell handover process includes a cross-CU LTM process, which is triggered by a first message. The first message includes a second parameter, which is used to generate the key corresponding to the first cell. The first condition includes one or more of the following: The first ID associated with the first target cell is the same as the first ID associated with the first cell; The first ID associated with the first target cell belongs to the first ID configuration; The first target cell is an LTM candidate cell; The first ID associated with the first target cell is different from the first ID associated with the source cell of the terminal device.

41. The terminal device according to claim 40, characterized in that, The first ID configuration is obtained through one or more of the following: the first message, the configuration for the source cell, and the configuration for the LTM candidate cell.

42. The terminal device according to claim 40 or 41, characterized in that, The terminal device is also used to generate a key for communicating with the first target cell using the second parameter.

43. The terminal device according to any one of claims 40-42, characterized in that, The first message includes an LTM switching command message.

44. The terminal device according to any one of claims 30-43, characterized in that, The first target cell belongs to the LTM candidate cell, or the conditional handover candidate target cell.

45. The terminal device according to claim 44, characterized in that, The first condition includes: The LTM candidate cell is configured to be allowed to be selected as the first target cell; and / or, The candidate target cell for conditional handover is configured to be allowed to be selected as the first target cell.

46. ​​The terminal device according to claim 44 or 45, characterized in that, When the cell handover process includes an LTM handover process, the first target cell selected by the terminal device needs to belong to the LTM candidate cell.

47. The terminal device according to any one of claims 44-46, characterized in that, When the cell handover process includes a conditional handover process, the first target cell selected by the terminal device needs to belong to the conditional handover candidate target cell.

48. The terminal device according to any one of claims 44-46, characterized in that, If the second condition is met, the terminal device does not apply the configuration of the first target cell, and the terminal device releases the LTM candidate cell configuration and / or the conditional handover candidate target cell configuration.

49. The terminal device according to claim 48, characterized in that, The second condition includes one or more of the following: The terminal device does not have the key corresponding to the first target cell; The first target cell is not an LTM candidate cell or a conditional handover candidate target cell; If the first target cell belongs to the LTM candidate cell and the first target cell is a cross-CU cell of the source cell of the terminal device.

50. The terminal device according to any one of claims 30-49, characterized in that, Before the terminal device selects the first target cell or when the cell handover process fails, the terminal device restores the configuration of the source cell of the terminal device.

51. The terminal device according to claim 50, characterized in that, In the event of a key update during the cell handover process, the configuration of the source cell for which the terminal device resumes application includes PDCP status variables; And / or, If there is no key update during the cell handover process, the configuration of the source cell for which the terminal device resumes application does not include PDCP state variables.

52. The terminal device according to any one of claims 30-51, characterized in that, The cell handover process includes at least one of the following: LTM process within a CU, LTM process between CUs, C-LTM process within a CU, C-LTM process between CUs, handover process triggered by RRC signaling, CHO process, CHO process based on SCG, and CHO process based on candidate SCG.

53. A network device, characterized in that, include: The sending unit is used to send the first parameter to the terminal device; The first parameter is used to generate the key corresponding to the first target cell, which is the cell selected by the terminal device in the event of an RLF and / or cell handover failure.

54. The network device according to claim 53, characterized in that, The first parameter is carried in the RRCReestablishment message or in the MAC CE.

55. The network device according to claim 53 or 54, characterized in that, The network device is also used to receive first request information sent by the terminal device; The first request information is used to request the sending of the first parameter.

56. The network device according to claim 55, characterized in that, The first request information is carried in the RRCReestablishmentRequest message or in MAC CE.

57. The network device according to claim 55 or 56, characterized in that, The first request information is also used to indicate whether the terminal device is configured with the first target cell.

58. The network device according to claim 57, characterized in that, The first request information includes one or more of the following: The first piece of information is used to indicate whether the terminal device is configured with the first target cell; The second piece of information is used to indicate whether the first target cell is an LTM candidate cell; The third piece of information is used to indicate the C-RNTI allocated by the first target cell to the terminal device.

59. A terminal device, characterized in that, The device includes a transceiver, a memory, and a processor. The memory stores a program, and the processor invokes the program in the memory and controls the transceiver to receive or send signals so that the terminal device performs the method as described in any one of claims 1-23.

60. A network device, characterized in that, The device includes a transceiver, a memory, and a processor. The memory stores a program, and the processor invokes the program in the memory and controls the transceiver to receive or transmit signals so that the network device performs the method as described in any one of claims 24-29.

61. An apparatus, characterized in that, Includes a processor for calling a program from memory to cause the device to perform the method as described in any one of claims 1-29.

62. A chip, characterized in that, Includes a processor for calling a program from memory, causing a device on which the chip is mounted to perform the method as described in any one of claims 1-29.

63. A computer-readable storage medium, characterized in that, It contains a program that causes a computer to perform the method as described in any one of claims 1-29.

64. A computer program product, characterized in that, Includes a program that causes a computer to perform the method as described in any one of claims 1-29.

65. A computer program, characterized in that, The computer program causes the computer to perform the method as described in any one of claims 1-29.

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