Consecutive handover method and apparatus, terminal, and readable storage medium

Abstract

The present application relates to the technical field of communications, and in particular to a consecutive handover method and apparatus, a terminal, and a readable storage medium. The method comprises: after handover to a first cell, a terminal executes a first operation, wherein the first operation comprises: in the absence of a key derivation parameter for next handover, the terminal determines not to perform handover-related processing for a first candidate cell, or, in the presence of a key derivation parameter for next handover, the terminal executes handover-related processing for a first candidate cell, or, when an RLF or HOF occurs, the terminal performs cell selection and performs recovery-related processing on the basis of a selected cell, wherein the ID associated with the first candidate cell is different from the ID associated with the first cell, and the ID is used for indicating whether key update or PDCP re-establishment needs to be executed in the case of handover or recovery to a target cell.

Description

Continuous switching method, device, terminal and readable storage medium

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application filed with the China Patent Office on December 6, 2023, with application number 202311671959.3 and invention name “Continuous switching method, device, terminal and readable storage medium”, the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present application belongs to the field of communication technology, and specifically relates to a continuous switching method, device, terminal and readable storage medium. Background Art

[0004] For continuous conditional handover (CHO) or conditional L1 / L2-triggered mobility (conditional LTM), the candidate cell configuration is not released after the handover is completed. The network needs to reconfigure the key derivation parameters after the previous handover to support the next handover. However, if the terminal initiates CHO or conditional LTM before the key derivation parameters are reconfigured, it will not be able to communicate normally with the target cell after receiving the RRC reconfiguration message. Summary of the Invention

[0005] The embodiments of the present application provide a continuous switching method, device, terminal and readable storage medium, which can solve the problem that if the terminal initiates CHO or conditional LTM before the key derivation parameters are reconfigured, the terminal will not be able to communicate normally with the target cell after receiving the RRC reconfiguration message.

[0006] In a first aspect, a continuous switching method is provided, the method comprising:

[0007] After switching to the first cell, the terminal performs a first operation;

[0008] The first operation includes:

[0009] In the absence of a key derivation parameter for the next handover, the terminal determines not to perform handover-related processing of the first candidate cell; or

[0010] In a case where a key derivation parameter for the next handover exists, the terminal performs handover-related processing of the first candidate cell; or

[0011] After RLF or HOF occurs, the terminal selects a cell and performs recovery-related processing according to the selected cell;

[0012] The ID associated with the first candidate cell is different from the ID associated with the first cell, and the ID is used to indicate whether key update or PDCP reconstruction is required when switching or restoring to the target cell.

[0013] In a second aspect, a continuous switching device is provided, the device comprising:

[0014] an execution module, configured to cause the terminal to execute a first operation after switching to the first cell;

[0015] The first operation includes:

[0016] In the absence of a key derivation parameter for the next handover, the terminal determines not to perform handover-related processing of the first candidate cell; or

[0017] In a case where a key derivation parameter for the next handover exists, the terminal performs handover-related processing of the first candidate cell; or

[0018] After RLF or HOF occurs, the terminal selects a cell and performs recovery-related processing according to the selected cell;

[0019] The ID associated with the first candidate cell is different from the ID associated with the first cell, and the ID is used to indicate whether key update or PDCP reconstruction is required when switching or restoring to the target cell.

[0020] In a third aspect, a terminal is provided, comprising a processor and a memory, wherein the memory stores a program or instruction that can be run on the processor, and when the program or instruction is executed by the processor, the steps of the method described in the first aspect are implemented.

[0021] In a fourth aspect, a readable storage medium is provided, on which a program or instruction is stored. When the program or instruction is executed by a processor, the steps of the method described in the first aspect are implemented.

[0022] In a fifth aspect, a wireless communication system is provided, including: a terminal and a network side device, wherein the terminal can be used to execute the steps of the method described in the first aspect.

[0023] In a sixth aspect, a chip is provided, comprising a processor and a communication interface, wherein the communication interface is coupled to the processor, and the processor is configured to run a program or instruction to implement the method described in the first aspect.

[0024] In a seventh aspect, a computer program / program product is provided, wherein the computer program / program product is stored in a storage medium, and the program / program product is executed by at least one processor to implement the method as described in the first aspect.

[0025] In an embodiment of the present application, when there are no key derivation parameters for the next handover, the terminal determines not to perform inter-CU handover to avoid the problem of being unable to communicate normally with the target cell after the handover; when there are key derivation parameters for the next handover, the terminal determines to perform inter-CU handover to ensure normal communication with the target cell; after RLF or HOF occurs, the terminal decides to perform recovery-related processing according to the selected cell situation to ensure that link recovery can be performed correctly. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] FIG1a is a block diagram of a wireless communication system applicable to embodiments of the present application;

[0027] Figure 1b is the architecture diagram of CU-DU;

[0028] Figure 1c is a schematic diagram of the LTM switching process;

[0029] Figure 1d is a schematic diagram of the CHO switching process;

[0030] FIG2 is a schematic flow chart of a continuous switching method according to an embodiment of the present application;

[0031] FIG3 is a schematic structural diagram of a continuous switching device provided in an embodiment of the present application;

[0032] FIG4 is a schematic diagram of the structure of a communication device provided in an embodiment of the present application;

[0033] FIG5 is a schematic diagram of the structure of a terminal provided in an embodiment of the present application. DETAILED DESCRIPTION

[0034] The following will be combined with the accompanying drawings in the embodiments of this application to clearly describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of this application.

[0035] The terms "first", "second", etc. in this application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the terms used in this way are interchangeable where appropriate, so that the embodiments of the present application can be implemented in an order other than those illustrated or described herein, and the objects distinguished by "first" and "second" are generally of the same type, and do not limit the number of objects, for example, the first object can be one or more. In addition, "or" in this application represents at least one of the connected objects. For example, "A or B" covers three options, namely, Option 1: including A but not including B; Option 2: including B but not including A; Option 3: including both A and B. The character " / " generally indicates that the objects associated before and after are in an "or" relationship.

[0036] The term "indication" in this application can be either a direct indication (or explicit indication) or an indirect indication (or implicit indication). A direct indication can be understood as the sender explicitly informing the receiver of specific information, the operation to be performed, or the requested result, etc. in the instruction sent; an indirect indication can be understood as the receiver determining the corresponding information based on the instruction sent by the sender, or making a judgment and determining the operation to be performed or the requested result, etc. based on the judgment result.

[0037] It is worth noting that the technology described in the embodiments of the present application is not limited to the Long Term Evolution (LTE) / LTE-Advanced (LTE-A) system, but can also be used in other wireless communication systems, such as Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), Single-carrier Frequency Division Multiple Access (SC-FDMA) or other systems. The terms "system" and "network" in the embodiments of the present application are often used interchangeably, and the described technology can be used for the systems and radio technologies mentioned above, as well as for other systems and radio technologies. The following description describes a New Radio (NR) system for example purposes, and NR terminology is used in most of the following description, but these technologies can also be applied to systems other than NR systems, such as 6th Generation (6G) communication systems.

[0038] FIG1a shows a block diagram of a wireless communication system applicable to an embodiment of the present application. The wireless communication system includes a terminal 11 and a network-side device 12. The terminal 11 may be a mobile phone, a tablet computer (Tablet Personal Computer), a laptop computer (Laptop Computer), a notebook computer, a personal digital assistant (PDA), a handheld computer, a netbook, an ultra-mobile personal computer (UMPC), a mobile internet device (MID), an augmented reality (AR), a virtual reality (VR) device, a robot, a wearable device (Wearable Device), an aircraft (flight vehicle), a vehicle user equipment (VUE), a ship-borne device, a pedestrian user equipment (PUE), a smart home (home appliances with wireless communication capabilities, such as refrigerators, televisions, washing machines, or furniture), a game console, a personal computer (PC), an ATM, or a self-service machine, or other terminal-side devices. Wearable devices include: smart watches, smart bracelets, smart headphones, smart glasses, smart jewelry (smart bracelets, smart bracelets, smart rings, smart necklaces, smart anklets, smart anklets, etc.), smart wristbands, smart clothing, etc. Among them, the vehicle-mounted device can also be called a vehicle-mounted terminal, a vehicle-mounted controller, a vehicle-mounted module, a vehicle-mounted component, a vehicle-mounted chip or a vehicle-mounted unit, etc. It should be noted that the specific type of the terminal 11 is not limited in the embodiment of the present application. The network side device 12 may include an access network device or a core network device, wherein the access network device may also be called a radio access network (Radio Access Network, RAN) device, a radio access network function or a radio access network unit. The access network device may include a base station, a wireless local area network (WLAN) access point (AP) or a wireless fidelity (WiFi) node, etc.Among them, the base station can be referred to as Node B (NB), Evolved Node B (eNB), the next generation Node B (gNB), New Radio Node B (NR Node B), access point, Relay Base Station (RBS), Serving Base Station (SBS), Base Transceiver Station (BTS), radio base station, radio transceiver, Basic Service Set (BSS), Extended Service Set (ESS), Home Node B (HNB), Home Evolved Node B (homeevolved Node B), Transmission Reception Point (TRP) or other appropriate terms in the relevant field. As long as the same technical effect is achieved, the base station is not limited to specific technical vocabulary. It should be noted that in the embodiment of the present application, only the base station in the NR system is used as an example for introduction, and the specific type of the base station is not limited.

[0039] The core network device may include but is not limited to at least one of the following: core network node, core network function, mobility management entity (MME), access mobility management function (AMF), session management function (SMF), user plane function (UPF), policy control function (PCF), policy and charging rules function unit (PCRF), edge application service discovery function (EASDF), unified data management (UDM), unified data storage (UDR), home user server (HSS), centralized network configuration (CNC), network storage function (NRF), network exposure function (NEF), local NEF (L-NEF), binding support function (BSF), network access function (UMF), network access function (UMF), network access function (UMF), network access function (UMF), network access function (UMF), network access function (UMF), network access function (UMF), network access function (UMF), network access function (UMF), network access function (UMF), network access function (UMF), network access function (UMF), network access function (UMF), network access function (UMF), network access function (UMF), network access function (UMF), network access function (UMF), network access function (UMF), network access function (UMF), network access function (UMF), network access function (UMF), network access function (UMF), network access function (UMF), network access function (UMF), network access function (UMF), network access function (UMF), network access function (UMF), network access function (UMF), network access function (UMF), network access function (UMF), network access function (UMF), network access function (UMF), network access function (UMF), network access function (UMF), network access function (UMF), network access function (UMF), network access function (UMF), network access function (UMF), network access function (UMF), Function, BSF), application function (Application Function, AF), etc. It should be noted that in the embodiment of the present application, only the core network device in the NR system is introduced as an example, and the specific type of the core network device is not limited.

[0040] To better understand the technical solution of this application, the following contents are first introduced:

[0041] Centralized Unit (CU)-Distributed Unit (DU) Architecture

[0042] The NR access network splits the gNB into the gNB-CU and gNB-DU, which are connected via the F1 interface. The CU-DU architecture is shown in Figure 1b.

[0043] Among them, a gNB contains only one CU, one or more DUs, and one DU contains one or more cells.

[0044] The CU includes the Packet Data Convergence Protocol (PDCP) and above protocol stacks, and the DU includes the protocol stack below the PDCP layer (Radio Link Control (RLC), Media Access Control (MAC), and Physical (PHY)).

[0045] On the control plane, the CU includes Radio Resource Control (RRC) and the PDCP (PDCP-C) of the control plane;

[0046] On the user plane, the CU includes the Service Data Adaptation Protocol (SDAP) and the PDCP of the user plane (PDCP-U).

[0047] LTM

[0048] To reduce handover latency, LTM (L1 / L2-triggered mobility) is introduced. The network preconfigures multiple LTM candidate cells. The DU uses L1 / L2 signaling to instruct the terminal to switch to the appropriate candidate cell based on the Layer 1 measurement results reported by the terminal. LTM only supports cell handover within the same CU. The specific process is shown in Figure 1c.

[0049] Continuous LTM: The UE switches continuously between multiple configured candidate cells without the network having to reconfigure the candidate cells.

[0050] CHO

[0051] To prevent the terminal from failing to receive the handover command message from the source node after the channel condition of the source cell deteriorates, thus causing handover failure, a conditional handover process is introduced. The specific process is shown in Figure 1d.

[0052] The main steps of the conditional switching process are as follows:

[0053] 1. During the measurement process, the UE reports a measurement report.

[0054] 2. The source node decides to use CHO.

[0055] 3. The source node sends a handover request message to one or more potential target nodes.

[0056] 4. The destination node may perform admission control

[0057] 5. The target node feeds back switching confirmation information to the source node.

[0058] 6. The source node sends RRC reconfiguration information including conditional handover to the UE.

[0059] 7. The UE sends an RRC reconfiguration complete (RRCReconfigurationComplete) message to the source node.

[0060] 8. The UE evaluates whether the candidate cells meet the conditions and selects a target cell for handover if the conditions are met.

[0061] The UE initiates a random access procedure in the selected target cell.

[0062] The UE sends an RRCReconfigurationComplete message to the target node.

[0063] After successfully completing the handover process, the UE releases the stored conditional handover configuration.

[0064] 8a. The target node sends a handover success message to the source node.

[0065] 8b. The source node sends a service network (SN) state transfer message to the target node.

[0066] 8c. The source node sends a handover cancellation message to other candidate nodes.

[0067] Currently supported CHO handover trigger conditions are A3 and A5 events. If two handover trigger conditions are configured at the same time, CHO or Conditional PSCell Addition / Change (CPAC) will be triggered only when both conditions are met.

[0068] Taking the A3 event as an example, the meanings of the parameters for the entry and exit conditions are as follows:

[0069] Mn: Neighboring cell measurement result, without considering any offset;

[0070] Ofn: Neighborhood measurement object specific offset;

[0071] Ocn: Neighboring cell-level specific offset;

[0072] Mp: SpCell (primary serving cell) measurement result, without considering any offset;

[0073] Ofp: SpCell measurement object specific offset;

[0074] Ocp: SpCell cell-level specific offset;

[0075] Hys: hysteresis parameter of the event;

[0076] Off: offset parameter of the event;

[0077] Mi: Neighboring cell interference measurement result.

[0078] To avoid ping-pong handover, the base station configures the trigger time (timeToTrigger) parameter for each event in the conditional trigger configuration (CondTriggerConfig). When the L3 filtered signal quality of one or more candidate cells within the timeToTrigger time meets the entry conditions of the event, the UE uses the cells that meet the conditions as trigger cells and selects one of the trigger cells to perform conditional reconfiguration.

[0079] Subsequent CHO

[0080] For continuous CHO handover, the candidate cell configuration will not be released after the handover, and the key of the candidate cell needs to be reconfigured after each handover, that is, the key derivation parameters are provided to the UE.

[0081] CHO based recovery

[0082] After a Radio Link Failure (RLF) or Handover Failure (HOF) occurs, the UE performs cell selection. If the selected cell is a CHO candidate cell and the network configuration attempt condition reconfiguration information element (attemptCondReconfig IE) is true, the UE attempts to perform a CHO. Otherwise, the UE performs a reestablishment.

[0083] For LTM or conditional LTM, LTM-based recovery methods similar to CHO-based recovery are also supported.

[0084] Conditional LTM

[0085] The difference between conditional LTM and LTM is that the UE evaluates network pre-configured events (similar to CHO conditions, conditional LTM conditions are based on L1 measurement definitions) to determine whether the handover conditions are met, and thus performs handover on its own without the need for the DU to indicate a handover command.

[0086] Subsequent conditional LTM

[0087] Conditional LTM can also support continuous handover, that is, the LTM candidate cell configuration is not released, and the key derivation parameters are reconfigured after each handover to support the next handover.

[0088] Key changes for Xn handover

[0089] Xn handover is an inter-CU handover achieved through the Xn interface between the source gNB / ng-eNB and the target gNB / ng-eNB. The key derivation process for the handover is as follows:

[0090] Network side:

[0091] a) When the source gNB / ng-eNB has an unused {NH, NCC} pair, vertical key derivation is performed. Otherwise, horizontal key derivation is performed. NH (Next Hop) is derived from the AMF key KAMF, and NCC is the NH chaining counter. If vertical key derivation is performed, the source gNB / ng-eNB calculates K based on the NH, the target cell's physical cell identifier (PCI), and the frequency. NG-RAN *; If horizontal key derivation is performed, the source gNB / ng-eNB uses the currently used key K gNB , using the PCI and frequency of the target cell as input to calculate K NG-RAN *;

[0092] b) The source gNB / ng-eNB will NG-RAN *,NCC}pair is sent to the target gNB / ng-eNB. The target gNB / ng-eNB uses K NG-RAN * As K when UE switches to the target cell gNB The target gNB / ng-eNB will use NCC and target K gNB The UE associates with the NCC and includes it in the HO Command message, transparently transmitting it to the source gNB / ng-eNB, which then sends it to the UE.

[0093] c) After the handover is completed, the target gNB / ng-eNB sends an NGAP PATH SWITCH REQUEST message to the AMF. After receiving the message, the AMF increases the locally saved NCC by 1 and AMF A new NH is derived, and the AMF sends the new {NH, NCC} to the target gNB / ng-eNB via NGAP PATH SWITCH REQUEST ACKNOWLEDGE for subsequent handovers, and deletes other saved {NH, NCC} pairs.

[0094] UE side:

[0095] When the UE performs a handover and applies the RRC configuration of the target cell:

[0096] - If the NCC value received by the UE in the handover command is the same as the K value currently used gNB / K eNB If the associated NCC is the same, the UE will use the current K gNB / K eNB， K is derived from the target PCI and frequency level NG-RAN *.

[0097] - If the NCC value received by the UE in the handover command is the same as the K value currently used gNB / K eNB If the associated NCC is different, the UE first synchronizes the NCC and NH until it matches the NCC indicated by the handover command. Then the UE vertically derives K based on the synchronized NH, target PCI and frequency. NG-RAN *.

[0098] UE uses K NG-RAN *K used for communication with target gNB / ng-eNB gNB / K eNB .

[0099] LTM supports two types of handover scenarios: intra-DU (within the same distributed unit) and intra-CU, inter-DU (within the same central unit, but different distributed units). Inter-CU LTM (within different central units) may be supported in the future. Furthermore, conditional LTM may also be supported, where the UE performs measurements based on handover events preconfigured by the network and switches to a candidate cell when the conditions are met. For CHO, support for continuous CHO may also be expanded.

[0100] Inter-CU handover involves a change in the PDCP entity on the network side, requiring a key change. Before the next handover, the target cell or candidate cell keys must be reconfigured, and a new NCC must be provided to the UE. For continuous LTM or continuous CHO handovers, the UE retains the candidate cell configuration for the successive handovers. Therefore, the UE may initiate a handover or a post-RLF / HOF recovery after the previous handover is complete but before the NCC for the next handover is received.

[0101] As can be seen above, for continuous CHO or conditional LTM, the candidate cell configuration is not released after the handover is completed. The network needs to reconfigure the NCC after the previous handover to support the next handover. However, if the UE initiates CHO or conditional LTM (normal handover or recovery-triggered handover) before receiving the NCC reconfiguration, how to apply the key and how to avoid incorrect handovers remain to be solved.

[0102] The continuous switching method provided in the embodiment of the present application is described in detail below through some embodiments and their application scenarios in conjunction with the accompanying drawings.

[0103] Referring to FIG. 2 , an embodiment of the present application provides a continuous switching method, which is performed by a terminal and includes:

[0104] Step 201: After switching to the first cell, the terminal performs a first operation;

[0105] The first operation includes:

[0106] (1) In the absence of key derivation parameters for the next handover, the terminal determines not to perform handover-related processing for the first candidate cell; the absence of key derivation parameters for the next handover means that the terminal has not yet received the key derivation parameters reconfigured by the network side, that is, before the key derivation parameters are reconfigured, the terminal does not perform handover-related processing operations. In this way, key usage errors can be avoided for the Inter-CU handover scenario.

[0107] (2) In the presence of key derivation parameters for the next handover, the terminal performs handover-related processing for the first candidate cell; the presence of key derivation parameters for the next handover means that the terminal has received key derivation parameters reconfigured by the network side, that is, after the key derivation parameters are reconfigured, the terminal performs handover-related processing to ensure that the correct key is used for the next handover. It should be noted that the terminal may receive the key derivation parameters reconfigured by the network side before or after handover to the first cell, and the embodiment of the present application does not specifically limit the execution order between the step of the terminal receiving the key derivation parameters reconfigured by the network side and the step of the terminal handing over to the first cell.

[0108] (3) After RLF or HOF occurs, the terminal selects a cell and performs recovery-related processing based on the selected cell. For failure recovery processing, the terminal performs corresponding processing based on the specific situation of the selected cell to ensure that the recovery processing operation is performed correctly.

[0109] The identifier (ID) associated with the first candidate cell is different from the ID associated with the first cell. The ID is used to indicate whether a key update or PDCP re-establishment is required when switching or reverting to the target cell. If the IDs are the same, a key update or PDCP re-establishment is required. If the IDs are different, the keys remain unchanged and the PDCP is not re-established.

[0110] Optionally, the key derivation parameter may be NCC.

[0111] Optionally, the key derivation parameter may also be a master key update indication (MasterKeyUpdate), which includes at least one of the following: an indication of whether the AMF key (KAMF) is changed, NCC, and NAS information nas-Container submitted to the upper layer.

[0112] For clarity, the following description of the scheme is based on the case where the key derivation parameter is NCC. The same applies to other types of key derivation parameter schemes and will not be repeated.

[0113] In an embodiment of the present application, when there are no key derivation parameters for the next handover, the terminal determines not to perform inter-CU handover to avoid the problem of being unable to communicate normally with the target cell after the handover; when there are key derivation parameters for the next handover, the terminal determines to perform inter-CU handover to ensure normal communication with the target cell; after RLF or HOF occurs, the terminal decides to perform recovery-related processing according to the selected cell situation to ensure that link recovery can be performed correctly.

[0114] In a possible implementation, when there is no key derivation parameter for the next handover, the terminal determines not to perform handover-related processing for the first candidate cell, including:

[0115] (1) If there are no key derivation parameters for the next handover, the terminal stops evaluating the handover condition of the first candidate cell;

[0116] After the handover is completed, the terminal suspends the condition evaluation of the first candidate cell before receiving the NCC for key derivation for the next handover; by stopping the condition evaluation of the first candidate cell, handover to the first candidate cell is prohibited.

[0117] (2) If there are no key derivation parameters for the next handover and the first candidate cell meets the handover execution condition, the terminal is prohibited from handing over to the first candidate cell.

[0118] After the handover is completed, the terminal is not allowed to switch to the first candidate cell before receiving the NCC for key derivation for the next handover, even if the condition evaluation of the first candidate cell is met.

[0119] Through the specific processing operations of (1) and (2) above, the specific processing operations of the terminal before the key derivation parameters are reconfigured are clarified, so that key usage errors can be avoided for the Inter-CU switching scenario.

[0120] In a possible implementation, when a key derivation parameter for a next handover exists, the terminal performs handover-related processing of the first candidate cell, including:

[0121] (1) When the key derivation parameters for the next handover exist, the terminal initiates handover condition evaluation of the first candidate cell;

[0122] After receiving the NCC for key derivation for the next handover, the terminal restarts the condition evaluation of the first candidate cell; by starting the condition evaluation of the first candidate cell, handover to the first candidate cell is allowed.

[0123] (2) If the key derivation parameter for the next handover exists and the first candidate cell meets the handover execution condition, the terminal switches to the first candidate cell.

[0124] After receiving the NCC for key derivation for the next handover and the condition evaluation of the first candidate cell is satisfied, the terminal is allowed to handover to the first candidate cell.

[0125] Through the specific processing operations of (1) and (2) above, the specific processing operations of the terminal after the key derivation parameters are reconfigured are clarified, so that key usage errors can be avoided for the Inter-CU switching scenario.

[0126] In a possible implementation, after RLF or HOF occurs, the terminal selects a cell and performs recovery-related processing according to the selected cell, including:

[0127] (1) After an RLF or HOF occurs, if there are no key derivation parameters for the next handover and the terminal selects the first candidate cell, the terminal performs the RRC connection reestablishment process, or the terminal does not perform CHO-based link recovery or LTM-based link recovery;

[0128] Before the terminal receives the NCC for key derivation for the next handover, if RLF or HOF occurs, the terminal performs cell selection. If the ID of the selected cell is different from that of the current source cell, that is, the ID of the first candidate cell is different from that of the first cell, the terminal performs the RRC connection reestablishment process, or the terminal does not perform CHO based recovery or LTM based recovery.

[0129] (2) When the network is configured with the first configuration and RLF or HOF occurs, if there are no key derivation parameters for the next handover and the cell selected by the terminal belongs to the second candidate cell in the CHO candidate cell set, the terminal performs CHO-based link recovery;

[0130] The first configuration is used to indicate whether the terminal performs CHO-based recovery after an RLF or HOF occurs. This first configuration can be recorded as attemptCondReconfig. If an RLF or HOF occurs before the UE receives the NCC for key derivation for the next handover, and the network configures a CHO handover attempt after the RLF / HOF (for example, by indicating attemptCondReconfig), the UE can only perform CHO-based recovery on a second candidate cell, which is a cell with the same association ID as the current source cell.

[0131] (3) When the network is configured with the second configuration and RLF or HOF occurs, if there are no key derivation parameters for the next handover and the cell selected by the terminal belongs to the second candidate cell in the LTM candidate cell set, the terminal performs LTM-based link recovery;

[0132] The second configuration is used to indicate whether the terminal performs LTM-based recovery after RLF or HOF occurs. This second configuration can be recorded as attemptLTM-Switch. If RLF or HOF occurs before the UE receives the NCC for key derivation for the next handover, and the network is configured to attempt LTM handover after RLF / HOF (for example, attemptLTM-Switch is indicated), the UE can only perform LTM based recovery on the second candidate cell, which is the cell with the same association ID as the current source cell.

[0133] (4) When the network is configured with the first configuration and RLF or HOF occurs, if key derivation parameters for the next handover exist and the cell selected by the terminal belongs to the second candidate cell in the CHO candidate cell set, the terminal performs CHO-based link recovery;

[0134] If RLF or HOF occurs before the UE receives the NCC for key derivation for the next handover, and the network configures that CHO handover can be attempted after RLF / HOF (for example, attemptCondReconfig is indicated), the UE can perform CHO based recovery on a cell in the CHO candidate cell set.

[0135] (5) When the network is configured with the second configuration and RLF or HOF occurs, if the key derivation parameters for the next handover exist and the cell selected by the terminal belongs to the second candidate cell in the LTM candidate cell set, the terminal performs LTM-based link recovery;

[0136] If RLF or HOF occurs before the UE receives the NCC for key derivation for the next handover, and the network is configured to attempt LTM handover after RLF / HOF (for example, attemptLTM-Switch is indicated), the UE can perform LTM based recovery on a cell in the LTM candidate cell set.

[0137] The ID associated with the second candidate cell is the same as the ID associated with the first cell.

[0138] The IDs associated with the cells in the above-mentioned CHO / LTM candidate cell set and the ID associated with the first cell may be the same or different.

[0139] Through the above (1) to (5), the specific operations of the terminal performing the recovery process based on the selected cell are clarified.

[0140] In one possible implementation, the method further includes:

[0141] (1) If the ID associated with the second cell is the same as the ID associated with the first cell, the terminal maintains the key unchanged and does not perform PDCP reestablishment;

[0142] (2) When the ID associated with the second cell is different from the ID associated with the first cell, the terminal derives a key based on the key derivation parameter and performs PDCP reestablishment;

[0143] The second cell is a cell selected during the CHO-based recovery process or the LTM-based recovery process.

[0144] During the above recovery process, if the cell selected based on the recovery has the same ID as the current source cell, that is, the ID associated with the second cell is the same as the ID associated with the first cell, the terminal maintains the key unchanged and does not perform PDCP re-establishment, which is applicable to non-inter-CU handover scenarios;

[0145] During the above-mentioned recovery process, if the cell selected based on recovery is different from the ID of the current source cell, that is, the ID associated with the second cell is different from the ID associated with the first cell, the terminal derives the key based on the key derivation parameter and performs PDCP reconstruction to apply to the inter-CU switching scenario.

[0146] The technical solution of this application is described below with reference to specific embodiments:

[0147] Example 1: Continuous CHO / Conditional LTM process with no NCC available;

[0148] 1. The UE receives at least one candidate cell configuration provided by the network (which may be a CHO or LTM candidate cell), where some candidate cells in the candidate cell configuration (i.e., inter-CU cells) are configured or associated with an NCC; each candidate cell configuration is associated with an ID, which is used to indicate whether the UE needs to perform a key update or PDCP re-establishment when switching to the candidate cell.

[0149] 2. The UE switches to a candidate cell that is configured or associated with an NCC (which can be NW triggered L3 HO, CHO, LTM or Conditional LTM) and uses this NCC for key derivation during the handover process;

[0150] 3. After the handover is completed, the UE suspends the condition evaluation of the first candidate cell before receiving the NCC for key derivation for the next handover, or does not allow handover to the first candidate cell even if the condition evaluation is met. The first candidate cell is a cell with a different association ID from the current source cell.

[0151] 4. After receiving the NCC for key derivation for the next handover, the UE restarts the condition evaluation of the first candidate cell, or allows handover to the first candidate cell after the condition evaluation is met.

[0152] Example 2: RLF / HOF occurs and no NCC is available during the recovery process;

[0153] 1-2 are the same as in Example 1;

[0154] 3. After handover is completed, if the UE experiences RLF or HOF before receiving the NCC for key derivation for the next handover, and the network has configured a CHO / LTM handover attempt after the RLF / HOF (for example, by indicating attemptCondReconfig or attemptLTM-Switch), the UE can only perform CHO-based recovery or LTM-based recovery on the second candidate cell, i.e., the cell with the same association ID as the current source cell.

[0155] 4. After the UE receives the NCC (which can be indicated by the RRC or LTM handover command) for key derivation for the next handover, if RLF / HOF occurs and the network is configured to attempt CHO / LTM handover after RLF / HOF, the UE can select any CHO candidate cell to perform CHO-based recovery or LTM candidate cell to perform LTM-based recovery. When performing recovery, if the source cell Association ID is the same as the target cell, the UE key remains unchanged and PDCP re-establishment is not performed. If the source cell Association ID is different from the target cell, the UE performs PDCP re-establishment based on the NCC-derived key during the recovery process.

[0156] The continuous switching method provided in the embodiment of the present application can be executed by a continuous switching device. In the embodiment of the present application, the continuous switching device provided in the embodiment of the present application is described by taking the continuous switching method executed by the continuous switching device as an example.

[0157] Referring to FIG3 , an embodiment of the present application provides a continuous switching device, which can be applied to a terminal. The device includes:

[0158] An execution module 301 is configured to cause the terminal to perform a first operation after switching to the first cell;

[0159] The first operation includes:

[0160] In the absence of a key derivation parameter for the next handover, the terminal determines not to perform handover-related processing of the first candidate cell; or

[0161] In a case where a key derivation parameter for the next handover exists, the terminal performs handover-related processing of the first candidate cell; or

[0162] After RLF or HOF occurs, the terminal selects a cell and performs recovery-related processing according to the selected cell;

[0163] The ID associated with the first candidate cell is different from the ID associated with the first cell, and the ID is used to indicate whether key update or PDCP reconstruction is required when switching or restoring to the target cell.

[0164] Optionally, the execution module is specifically configured to:

[0165] In the absence of a key derivation parameter for the next handover, the terminal stops evaluating the handover condition of the first candidate cell; or

[0166] In a case where there is no key derivation parameter for the next handover and the first candidate cell meets a handover execution condition, the terminal is prohibited from handing over to the first candidate cell.

[0167] Optionally, the execution module is specifically configured to:

[0168] In the case where the key derivation parameter for the next handover exists, the terminal initiates handover condition evaluation of the first candidate cell; or,

[0169] In a case where a key derivation parameter for a next handover exists and the first candidate cell meets a handover execution condition, the terminal hands over to the first candidate cell.

[0170] Optionally, the execution module is specifically configured to:

[0171] After an RLF or HOF occurs, if there is no key derivation parameter for the next handover and the terminal selects the first candidate cell, the terminal performs a radio resource control RRC connection reestablishment procedure, or the terminal does not perform a link recovery based on conditional handover CHO or a link recovery based on layer 1-2 triggered mobility LTM; or,

[0172] When the network is configured with the first configuration and RLF or HOF occurs, if there is no key derivation parameter for the next handover, and the cell selected by the terminal belongs to the second candidate cell in the CHO candidate cell set, the terminal performs CHO-based link recovery; or,

[0173] When the network is configured with the second configuration and RLF or HOF occurs, if there is no key derivation parameter for the next handover, and the cell selected by the terminal belongs to the second candidate cell in the LTM candidate cell set, the terminal performs LTM-based link recovery;

[0174] In a case where the network is configured with the first configuration and RLF or HOF occurs, if there are key derivation parameters for the next handover and the cell selected by the terminal belongs to the second candidate cell in the CHO candidate cell set, the terminal performs CHO-based link recovery; or,

[0175] When the network is configured with the second configuration and RLF or HOF occurs, if there are key derivation parameters for the next handover and the cell selected by the terminal belongs to the second candidate cell in the LTM candidate cell set, the terminal performs LTM-based link recovery;

[0176] The ID associated with the second candidate cell is the same as the ID associated with the first cell, the first configuration is used to indicate whether the terminal performs CHO-based recovery processing after RLF or HOF occurs, and the second configuration is used to indicate whether the terminal performs LTM-based recovery processing after RLF or HOF occurs.

[0177] Optionally, the device further comprises:

[0178] Processing module for:

[0179] In a case where the ID associated with the second cell is the same as the ID associated with the first cell, the terminal maintains the key unchanged and does not perform PDCP re-establishment; or,

[0180] In a case where the ID associated with the second cell is different from the ID associated with the first cell, the terminal derives a key based on the key derivation parameter and performs PDCP re-establishment;

[0181] The second cell is a cell selected during the CHO-based recovery process or the LTM-based recovery process.

[0182] The continuous switching device in the embodiments of the present application can be an electronic device, such as an electronic device with an operating system, or a component in an electronic device, such as an integrated circuit or chip. The electronic device can be a terminal, or it can be other devices other than a terminal. For example, the terminal can include but is not limited to the types of terminal 11 listed above, and other devices can be servers, network attached storage (NAS), etc., which are not specifically limited in the embodiments of the present application.

[0183] The switching device provided in the embodiment of the present application can implement each process implemented in the method embodiment of Figure 2 and achieve the same technical effect. To avoid repetition, it will not be repeated here.

[0184] As shown in Figure 4, an embodiment of the present application further provides a communication device 400, including a processor 401 and a memory 402. The memory 402 stores a program or instruction that can be run on the processor 401. For example, when the communication device 400 is a terminal, the program or instruction is executed by the processor 401 to implement the various steps of the above-mentioned method embodiment and can achieve the same technical effect. When the communication device 400 is a network-side device, the program or instruction is executed by the processor 401 to implement the various steps of the above-mentioned method embodiment and can achieve the same technical effect. To avoid repetition, it will not be repeated here.

[0185] The present application also provides a terminal including a processor and a communication interface, wherein the communication interface is coupled to the processor, and the processor is configured to execute a program or instruction to implement the steps described in the method embodiment. This terminal embodiment corresponds to the aforementioned terminal-side method embodiment, and each implementation process and implementation method of the aforementioned method embodiment is applicable to this terminal embodiment and can achieve the same technical effects. Specifically, Figure 5 is a schematic diagram of the hardware structure of a terminal implementing the present application embodiment.

[0186] The terminal 500 includes but is not limited to: a radio frequency unit 501, a network module 502, an audio output unit 503, an input unit 504, a sensor 505, a display unit 506, a user input unit 507, an interface unit 508, a memory 509 and at least some of the components of the processor 510.

[0187] Those skilled in the art will appreciate that the terminal 500 may also include a power supply (such as a battery) to power various components. The power supply may be logically connected to the processor 510 through a power management system, thereby implementing functions such as charging, discharging, and power consumption management through the power management system. The terminal structure shown in FIG5 does not constitute a limitation of the terminal. The terminal may include more or fewer components than shown, or combine certain components, or have different component arrangements, which will not be described in detail here.

[0188] It should be understood that in an embodiment of the present application, the input unit 504 may include a graphics processing unit (GPU) 5041 and a microphone 5042, and the graphics processor 5041 processes the image data of a static picture or video obtained by an image capture device (such as a camera) in a video capture mode or an image capture mode. The display unit 506 may include a display panel 5061, and the display panel 5061 may be configured in the form of a liquid crystal display, an organic light emitting diode, etc. The user input unit 507 includes a touch panel 5071 and at least one of other input devices 5072. The touch panel 5071 is also called a touch screen. The touch panel 5071 may include two parts: a touch detection device and a touch controller. Other input devices 5072 may include, but are not limited to, a physical keyboard, function keys (such as volume control keys, switch keys, etc.), a trackball, a mouse, and a joystick, which will not be repeated here.

[0189] In the embodiment of the present application, after receiving downlink data from a network-side device, the radio frequency unit 501 may transmit the data to the processor 510 for processing. Furthermore, the radio frequency unit 501 may send uplink data to the network-side device. Typically, the radio frequency unit 501 includes, but is not limited to, an antenna, an amplifier, a transceiver, a coupler, a low-noise amplifier, a duplexer, and the like.

[0190] The memory 509 can be used to store software programs or instructions and various data. The memory 509 may mainly include a first storage area for storing programs or instructions and a second storage area for storing data, wherein the first storage area may store an operating system, applications or instructions required for at least one function (such as a sound playback function, an image playback function, etc.). In addition, the memory 509 may include a volatile memory or a non-volatile memory. Among them, the non-volatile memory may be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or a flash memory. The volatile memory may be a random access memory (RAM), a static random access memory (SRAM), a dynamic random access memory (DRAM), a synchronous dynamic random access memory (SDRAM), a double data rate synchronous dynamic random access memory (DDRSDRAM), an enhanced synchronous dynamic random access memory (ESDRAM), a synchronous link dynamic random access memory (SLDRAM), and a direct memory bus random access memory (DRRAM). The memory 509 in the embodiment of the present application includes but is not limited to these and any other suitable types of memory.

[0191] Processor 510 may include one or more processing units. Optionally, processor 510 integrates an application processor and a modem processor. The application processor primarily handles operations related to the operating system, user interface, and application programs, while the modem processor primarily processes wireless communication signals, such as a baseband processor. It is understood that the modem processor may not be integrated into processor 510.

[0192] The processor 510 is configured to, after switching to the first cell, cause the terminal to perform a first operation;

[0193] The first operation includes:

[0194] In the absence of a key derivation parameter for the next handover, the terminal determines not to perform handover-related processing of the first candidate cell; or

[0195] In a case where a key derivation parameter for the next handover exists, the terminal performs handover-related processing of the first candidate cell; or

[0196] After RLF or HOF occurs, the terminal selects a cell and performs recovery-related processing according to the selected cell;

[0197] The ID associated with the first candidate cell is different from the ID associated with the first cell, and the ID is used to indicate whether key update or PDCP reconstruction is required when switching or restoring to the target cell.

[0198] Optionally, the processor 510 is specifically configured to:

[0199] In the absence of a key derivation parameter for the next handover, the terminal stops evaluating the handover condition of the first candidate cell; or

[0200] In a case where there is no key derivation parameter for the next handover and the first candidate cell meets a handover execution condition, the terminal is prohibited from handing over to the first candidate cell.

[0201] Optionally, the processor 510 is specifically configured to:

[0202] In the case where the key derivation parameter for the next handover exists, the terminal initiates handover condition evaluation of the first candidate cell; or,

[0203] In a case where a key derivation parameter for a next handover exists and the first candidate cell meets a handover execution condition, the terminal hands over to the first candidate cell.

[0204] Optionally, the processor 510 is specifically configured to:

[0205] After an RLF or HOF occurs, if there is no key derivation parameter for the next handover and the terminal selects the first candidate cell, the terminal performs a radio resource control RRC connection reestablishment procedure, or the terminal does not perform a link recovery based on conditional handover CHO or a link recovery based on layer 1-2 triggered mobility LTM; or,

[0206] When the network is configured with the first configuration and RLF or HOF occurs, if there is no key derivation parameter for the next handover, and the cell selected by the terminal belongs to the second candidate cell in the CHO candidate cell set, the terminal performs CHO-based link recovery; or,

[0207] When the network is configured with the second configuration and RLF or HOF occurs, if there is no key derivation parameter for the next handover, and the cell selected by the terminal belongs to the second candidate cell in the LTM candidate cell set, the terminal performs LTM-based link recovery;

[0208] In a case where the network is configured with the first configuration and RLF or HOF occurs, if there are key derivation parameters for the next handover and the cell selected by the terminal belongs to the second candidate cell in the CHO candidate cell set, the terminal performs CHO-based link recovery; or,

[0209] When the network is configured with the second configuration and RLF or HOF occurs, if there are key derivation parameters for the next handover and the cell selected by the terminal belongs to the second candidate cell in the LTM candidate cell set, the terminal performs LTM-based link recovery;

[0210] The ID associated with the second candidate cell is the same as the ID associated with the first cell, the first configuration is used to indicate whether the terminal performs CHO-based recovery processing after RLF or HOF occurs, and the second configuration is used to indicate whether the terminal performs LTM-based recovery processing after RLF or HOF occurs.

[0211] Optionally, the processor 510 is configured to:

[0212] In a case where the ID associated with the second cell is the same as the ID associated with the first cell, the terminal maintains the key unchanged and does not perform PDCP re-establishment; or,

[0213] In a case where the ID associated with the second cell is different from the ID associated with the first cell, the terminal derives a key based on the key derivation parameter and performs PDCP re-establishment;

[0214] The second cell is a cell selected during the CHO-based recovery process or the LTM-based recovery process.

[0215] It can be understood that the implementation process of each implementation method mentioned in this embodiment can refer to the relevant description of the method embodiment and achieve the same or corresponding technical effects. To avoid repetition, it will not be described here.

[0216] An embodiment of the present application also provides a readable storage medium, on which a program or instruction is stored. When the program or instruction is executed by a processor, the various processes of the above-mentioned method embodiment are implemented and the same technical effect can be achieved. To avoid repetition, it will not be repeated here.

[0217] The processor is the processor in the terminal described in the above embodiment. The readable storage medium includes a computer-readable storage medium, such as a computer read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk. In some examples, the readable storage medium may be a non-transitory readable storage medium.

[0218] An embodiment of the present application further provides a chip, which includes a processor and a communication interface, wherein the communication interface is coupled to the processor, and the processor is used to run programs or instructions to implement the various processes of the above-mentioned method embodiment and achieve the same technical effect. To avoid repetition, it will not be repeated here.

[0219] It should be understood that the chip mentioned in the embodiments of the present application can also be called a system-level chip, a system chip, a chip system or a system-on-chip chip, etc.

[0220] An embodiment of the present application further provides a computer program / program product, which is stored in a storage medium. The computer program / program product is executed by at least one processor to implement the various processes of the above-mentioned method embodiment and can achieve the same technical effect. To avoid repetition, it will not be repeated here.

[0221] An embodiment of the present application further provides a wireless communication system, including: a terminal and a network-side device, wherein the terminal can be used to execute the steps of the continuous switching method as described above.

[0222] It should be noted that, in this article, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device comprising the element. In addition, it should be pointed out that the scope of the methods and devices in the embodiments of the present application is not limited to performing functions in the order shown or discussed, and may also include performing functions in a substantially simultaneous manner or in the opposite order according to the functions involved. For example, the described method may be performed in an order different from that described, and various steps may also be added, omitted or combined. In addition, the features described with reference to certain examples may be combined in other examples.

[0223] Through the description of the above embodiments, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of a computer software product plus a necessary general-purpose hardware platform, or of course, by hardware. The computer software product is stored in a storage medium (such as ROM, RAM, magnetic disk, optical disk, etc.) and includes a number of instructions for enabling a terminal or network-side device to execute the methods described in each embodiment of the present application.

[0224] The embodiments of the present application are described above in conjunction with the accompanying drawings, but the present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of this application, ordinary technicians in this field can also make many forms of implementation methods without departing from the purpose of this application and the scope of protection of the claims. These implementation methods are all within the protection of this application.

Claims

1. A continuous switching method, wherein: The method comprises: After switching to the first cell, the terminal performs a first operation; The first operation includes: In the absence of a key derivation parameter for the next handover, the terminal determines not to perform handover-related processing of the first candidate cell; or, In the case where the key derivation parameter for the next handover exists, the terminal performs handover-related processing of the first candidate cell; or, After a radio link failure (RLF) or a handover failure (HOF) occurs, the terminal selects a cell and performs recovery-related processing according to the selected cell; The identification ID associated with the first candidate cell is different from the ID associated with the first cell, and the ID is used to indicate whether key update or packet data convergence layer protocol PDCP reconstruction is required when switching or restoring to the target cell.

2. The method according to claim 1, wherein: In the case where there is no key derivation parameter for the next handover, the terminal determines not to perform handover-related processing of the first candidate cell, including: In the absence of a key derivation parameter for the next handover, the terminal stops the handover condition evaluation of the first candidate cell; or, When there is no key derivation parameter for the next handover and the first candidate cell meets the handover execution condition, the terminal is prohibited from handing over to the first candidate cell.

3. The method according to claim 1, wherein: The terminal performing, in a case where the key derivation parameter for the next handover exists, handover-related processing of the first candidate cell, includes: In the case where the key derivation parameter for the next handover exists, the terminal starts a handover condition evaluation of the first candidate cell; or, In a case where there are key derivation parameters for next handover and the first candidate cell meets a handover execution condition, the terminal switches to the first candidate cell.

4. The method according to claim 1, wherein: After the RLF or HOF occurs, the terminal selects a cell and performs recovery-related processing according to the selected cell, including: After RLF or HOF occurs, if there is no key derivation parameter for the next handover and the terminal selects the first candidate cell, the terminal performs a radio resource control RRC connection reestablishment process, or the terminal does not perform a link recovery based on conditional handover CHO or a link recovery based on layer 1-2 triggered mobility LTM; or, When the network configures the first configuration and RLF or HOF occurs, if there is no key derivation parameter for the next handover, and the cell selected by the terminal belongs to the second candidate cell in the CHO candidate cell set, the terminal performs CHO-based link recovery; or, When the network is configured with the second configuration and RLF or HOF occurs, if there is no key derivation parameter for the next handover, and the cell selected by the terminal belongs to the second candidate cell in the LTM candidate cell set, the terminal performs LTM-based link recovery; When the network configures the first configuration and RLF or HOF occurs, if there is a key derivation parameter for the next handover, and the cell selected by the terminal belongs to the second candidate cell in the CHO candidate cell set, the terminal performs CHO-based link recovery; or, When the network is configured with the second configuration and RLF or HOF occurs, if there is a key derivation parameter for the next handover, and the cell selected by the terminal belongs to the second candidate cell in the LTM candidate cell set, the terminal performs LTM-based link recovery; Among them, the ID associated with the second candidate cell is the same as the ID associated with the first cell, the first configuration is used to indicate whether the terminal performs CHO-based recovery processing after RLF or HOF occurs, and the second configuration is used to indicate whether the terminal performs LTM-based recovery processing after RLF or HOF occurs.

5. The method according to claim 1 or 4, wherein: The method further comprises: In a case where the ID associated with the second cell is the same as the ID associated with the first cell, the terminal maintains the key unchanged and does not perform PDCP reestablishment; or, In a case where the ID associated with the second cell is different from the ID associated with the first cell, the terminal derives a key based on the key derivation parameter and performs PDCP reestablishment; The second cell is a cell selected during the CHO-based recovery process or the LTM-based recovery process.

6. A continuous switching device, wherein: The device comprises: An execution module, configured to cause the terminal to execute a first operation after switching to the first cell; The first operation includes: In the absence of a key derivation parameter for the next handover, the terminal determines not to perform handover-related processing of the first candidate cell; or, In the case where the key derivation parameter for the next handover exists, the terminal performs handover-related processing of the first candidate cell; or, After RLF or HOF occurs, the terminal selects a cell and performs recovery-related processing according to the selected cell; The ID associated with the first candidate cell is different from the ID associated with the first cell, and the ID is used to indicate whether key update or PDCP reconstruction is required when switching or restoring to the target cell.

7. The device according to claim 6, wherein: The execution module is specifically used for: In the absence of a key derivation parameter for the next handover, the terminal stops the handover condition evaluation of the first candidate cell; or, When there is no key derivation parameter for the next handover and the first candidate cell meets the handover execution condition, the terminal is prohibited from handing over to the first candidate cell.

8. The device according to claim 6, wherein: The execution module is specifically used for: In the case where there are key derivation parameters for the next handover, the terminal initiates a handover condition evaluation of the first candidate cell; or, In a case where there are key derivation parameters for next handover and the first candidate cell meets a handover execution condition, the terminal switches to the first candidate cell.

9. The device according to claim 6, wherein: The execution module is specifically used for: After RLF or HOF occurs, if there is no key derivation parameter for the next handover, and the terminal selects the first candidate cell, the terminal performs an RRC connection reestablishment process, or the terminal does not perform CHO-based link recovery or LTM-based link recovery; or, In the case where the network is configured with the first configuration and RLF or HOF occurs, if there is no key derivation parameter for the next handover, and the cell selected by the terminal belongs to the second candidate cell in the CHO candidate cell set, the terminal performs CHO-based link recovery; or, When the network is configured with the second configuration and RLF or HOF occurs, if there is no key derivation parameter for the next handover, and the cell selected by the terminal belongs to the second candidate cell in the LTM candidate cell set, the terminal performs LTM-based link recovery; In the case where the network is configured with the first configuration and RLF or HOF occurs, if there is a key derivation parameter for the next handover, and the cell selected by the terminal belongs to the second candidate cell in the CHO candidate cell set, the terminal performs CHO-based link recovery; or, When the network is configured with the second configuration and RLF or HOF occurs, if there is a key derivation parameter for the next handover, and the cell selected by the terminal belongs to the second candidate cell in the LTM candidate cell set, the terminal performs LTM-based link recovery; Among them, the ID associated with the second candidate cell is the same as the ID associated with the first cell, the first configuration is used to indicate whether the terminal performs CHO-based recovery processing after RLF or HOF occurs, and the second configuration is used to indicate whether the terminal performs LTM-based recovery processing after RLF or HOF occurs.

10. The device according to claim 6 or 9, wherein: The device also includes: Processing modules for: In a case where the ID associated with the second cell is the same as the ID associated with the first cell, the terminal maintains the key unchanged and does not perform PDCP reestablishment; or, In a case where the ID associated with the second cell is different from the ID associated with the first cell, the terminal derives a key based on the key derivation parameter and performs PDCP reestablishment; The second cell is a cell selected during the CHO-based recovery process or the LTM-based recovery process.

11. A terminal, wherein: The method comprises a processor and a memory, wherein the memory stores a program or instruction that can be run on the processor, and when the program or instruction is executed by the processor, the steps of the continuous switching method according to any one of claims 1 to 5 are implemented.

12. A readable storage medium, wherein: The readable storage medium stores a program or instruction, and when the program or instruction is executed by a processor, the steps of the continuous switching method according to any one of claims 1 to 5 are implemented.

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