Cell handover methods, devices, terminals and network-side equipment

Abstract

This application discloses a cell handover method, apparatus, terminal, and network-side equipment, belonging to the field of communication technology. The cell handover method of this application includes: a terminal receiving first information sent by a network-side equipment, the first information being used to generate a key; the terminal determining whether to perform cell handover based on the first information based on a source cell and a target cell for cell handover; and, if the terminal performs cell handover and the handover fails, the terminal determining whether to perform fast recovery based on the first information during the Radio Resource Control (RRC) connection reconstruction process.

Description

Technical Field

[0001] This application belongs to the field of communication technology, specifically relating to a cell handover method, apparatus, terminal, and network-side equipment. Background Technology

[0002] In related technologies, network-side devices can use handover commands to instruct terminals whether to change the security key. If the handover command carries key information, the terminal uses a different key 1 than the source cell when exchanging signaling or data with the target cell; if the handover command does not carry key information, the terminal uses the same key 2 as the source cell when exchanging signaling or data with the target cell.

[0003] To reduce access latency, in the event of a cell handover failure, the terminal executes a Radio Resource Control (RRC) connection reconstruction process. During RRC connection reconstruction, the terminal has a certain opportunity to execute a fast recovery procedure. In the RRC connection reconstruction process, the terminal first selects a cell. If the selected cell (the first cell) is a pre-configured candidate handover target cell (i.e., the terminal has saved the network's pre-configured first cell as the handover target cell), the terminal can directly apply the saved first cell as the handover target cell configuration and send an uplink message (such as a handover completion message or an RRC reconfiguration completion message) to the first cell to switch to it; this process is called the fast recovery procedure. The terminal needs to use a key (key 3) that matches the first cell for fast recovery.

[0004] The processing flow on the network side and terminal side used to transmit key information in related technologies may prevent the terminal from obtaining or applying the appropriate key, resulting in the terminal being unable to quickly recover after a handover failure, thus leading to a large access latency. Summary of the Invention

[0005] This application provides a cell handover method, apparatus, terminal, and network-side equipment that can solve the problem of large access latency.

[0006] Firstly, a cell handover method is provided, executed by a terminal, the method comprising:

[0007] The terminal receives first information sent by the network-side device, and the first information is used to generate a key;

[0008] The terminal determines whether to perform cell handover based on the first information, based on the source cell and the target cell for cell handover.

[0009] If the terminal performs a cell handover and the handover fails, the terminal determines whether to perform a fast recovery based on the first information during the Radio Resource Control (RRC) connection reconstruction process.

[0010] Secondly, a cell handover method is provided, executed by a network-side device, the method comprising:

[0011] The network-side device sends a handover command to the terminal. The handover command is used to indicate the target cell for handover and carries first information.

[0012] During the process of the terminal switching to the target cell, the network-side device communicates with the terminal using a second key, which is a key corresponding to the source cell;

[0013] The first information is used for rapid recovery after the terminal fails to switch over.

[0014] Thirdly, a cell handover device is provided, comprising:

[0015] A receiving module is used to receive first information sent by a network-side device, wherein the first information is used to generate a key.

[0016] The processing module is used to determine whether to perform cell handover based on the first information, based on the source cell and the target cell for cell handover.

[0017] The processing module is further configured to determine, in the event that the terminal performs a cell handover and the handover fails, whether to perform rapid recovery based on the first information during the Radio Resource Control (RRC) connection reconstruction process.

[0018] Fourthly, a cell handover device is provided, comprising:

[0019] The sending module is used to send a handover command to the terminal, wherein the handover command is used to indicate the target cell for handover, and the handover command carries first information;

[0020] During the process of the terminal switching to the target cell, the network-side device communicates with the terminal using a second key, which is a key corresponding to the source cell;

[0021] The first information is used for rapid recovery after the terminal fails to switch over.

[0022] Fifthly, a cell handover apparatus is provided, the apparatus being configured to perform the steps of the method described in the first aspect, or to implement the steps of the method described in the second aspect.

[0023] In a sixth aspect, a terminal is provided, the terminal including a processor and a memory, the memory storing a program or instructions executable on the processor, the program or instructions, when executed by the processor, implementing the steps of the method as described in the first aspect.

[0024] Seventhly, a terminal is provided, including a processor and a communication interface, wherein,

[0025] A communication interface is used to receive first information sent by a network-side device, the first information being used to generate a key;

[0026] The processor is configured to determine, based on the source cell and the target cell for cell handover, whether to perform cell handover based on the first information;

[0027] The processor is further configured to determine, in the event that the terminal is performing a cell handover and the handover fails, whether to perform rapid recovery based on the first information during the Radio Resource Control (RRC) connection reconstruction process.

[0028] Eighthly, a network-side device is provided, the network-side device including a processor and a memory, the memory storing a program or instructions executable on the processor, the program or instructions, when executed by the processor, implementing the steps of the method as described in the second aspect.

[0029] Ninthly, a network-side device is provided, including a processor and a communication interface, wherein,

[0030] A communication interface is used to send a handover command to the terminal, the handover command being used to indicate the target cell for handover, and the handover command carrying first information;

[0031] During the process of the terminal switching to the target cell, the network-side device communicates with the terminal using a second key, which is a key corresponding to the source cell;

[0032] The first information is used for rapid recovery after the terminal fails to switch over.

[0033] In a tenth aspect, a readable storage medium is provided, on which a program or instructions are stored, which, when executed by a processor, implement the steps of the method described in the first aspect, or implement the steps of the method described in the second aspect.

[0034] Eleventhly, a wireless communication system is provided, comprising: a terminal and a network-side device, wherein the terminal can be used to perform the steps of the method as described in the first aspect, and the network-side device can be used to perform the steps of the method as described in the second aspect.

[0035] In a twelfth aspect, a chip is provided, the chip including a processor and a communication interface coupled to the processor, the processor being configured to run a program or instructions to implement the steps of the method described in the first aspect, or to implement the steps of the method described in the second aspect.

[0036] In a thirteenth aspect, a computer program / program product is provided, which is stored in a storage medium and is executed by at least one processor to implement the method as described in the first aspect, or to implement the method as described in the second aspect.

[0037] In this embodiment, the terminal receives first information sent by a network-side device, the first information being used to generate a key. The terminal determines whether to perform cell handover based on the first information, using the source cell and the target cell for cell handover. If the terminal performs cell handover and the handover fails, the terminal determines whether to perform fast recovery based on the first information during the Radio Resource Control (RRC) connection reconstruction process. In this way, the terminal can obtain and apply appropriate keys through the first information for cell handover or fast recovery, thereby successfully completing the handover process or successfully performing fast recovery after a handover failure (e.g., due to insufficient link quality between the terminal and the target cell), thus reducing access latency. Attached Figure Description

[0038] Figure 1 This is a block diagram of a wireless communication system applicable to embodiments of this application;

[0039] Figure 2a It is an LTM flowchart in related technologies;

[0040] Figure 2b This is a schematic diagram of a key chain switching model in related technologies;

[0041] Figure 3 This is one of the flowcharts of a cell handover method provided in the embodiments of this application;

[0042] Figure 4 This is a second flowchart of a cell handover method provided in the embodiments of this application;

[0043] Figure 5 This is one of the structural schematic diagrams of a cell handover device provided in the embodiments of this application;

[0044] Figure 6 This is a second schematic diagram of the structure of a cell handover device provided in the embodiments of this application;

[0045] Figure 7 This is a schematic diagram of the structure of a communication device provided in an embodiment of this application;

[0046] Figure 8 This is a schematic diagram of the structure of a terminal provided in an embodiment of this application;

[0047] Figure 9 This is one of the structural schematic diagrams of a network-side device provided in the embodiments of this application;

[0048] Figure 10 This is a second schematic diagram of the structure of a network-side device provided in an embodiment of this application. Detailed Implementation

[0049] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0050] The terms "first," "second," etc., used in this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first" and "second" are generally of the same class, not limited in number; for example, the first object can be one or more. Furthermore, "or" in this application indicates at least one of the connected objects. For example, the scope of protection for "A or B" covers at least three scenarios: Scenario 1: including A but not B; Scenario 2: including B but not A; Scenario 3: including both A and B. In addition, the terms "A and / or B," "at least one of A and B," and "at least one of A or B" also cover at least the above three scenarios. The character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0051] The term "instruction" in this application can be either a direct instruction (or explicit instruction) or an indirect instruction (or implicit instruction). A direct instruction can be understood as the sender explicitly informing the receiver of specific information, the required operation, or the requested result in the instruction sent. An indirect instruction 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 required operation or requested result based on the judgment result.

[0052] It is worth noting that the technologies described in this application are not limited to Long Term Evolution (LTE) / LTE-Advanced (LTE-A) systems, 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 this application are often used interchangeably, and the described technologies can be used in the systems and radio technologies mentioned above, as well as in other systems and radio technologies. The following description describes New Radio (NR) systems for illustrative purposes, and the term NR is used in most of the following description; however, these technologies can also be applied to systems other than NR systems, such as 6th Generation (6G) communication systems.

[0053] Figure 1This diagram illustrates a block diagram of a wireless communication system applicable to embodiments of this application. The wireless communication system includes a terminal 11 and a network-side device 12. The terminal 11 can also be referred to as User Equipment (UE), and can be a mobile phone, tablet computer, laptop computer, notebook computer, personal digital assistant (PDA), handheld computer, netbook, ultra-mobile personal computer (UMPC), mobile internet device (MID), augmented reality (AR), virtual reality (VR) device, robot, wearable device, flight vehicle, vehicle user equipment (VUE), shipboard equipment, pedestrian user equipment (PUE), smart home devices (home appliances with wireless communication capabilities, such as refrigerators, televisions, washing machines, or furniture), game consoles, personal computers (PCs), ATMs, or self-service machines, etc. Wearable devices include: smartwatches, smart bracelets, smart earphones, smart glasses, smart jewelry (smart bracelets, smart chains, smart rings, smart necklaces, smart anklets, smart anklets, etc.), smart wristbands, smart clothing, etc. Among these, in-vehicle devices can also be referred to as in-vehicle terminals, in-vehicle controllers, in-vehicle modules, in-vehicle components, in-vehicle chips, or in-vehicle units, etc. It should be noted that the specific type of terminal 11 is not limited in this application embodiment. Network-side equipment 12 may include access network equipment or core network equipment, wherein access network equipment may also be referred to as Radio Access Network (RAN) equipment, radio access network function, or radio access network unit. Access network equipment may include base stations, Wireless Local Area Network (WLAN) access points (APs), or Wireless Fidelity (WiFi) nodes, etc.Among them, base stations can be referred to as Node B (NB), Evolved Node B (eNB), 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, Transmission and Reception Point (TRP), and Non-Terrestrial Network (NTN) equipment (such as satellite or high altitude platform). The term "base station" can be any suitable term in the field, such as "station" or any other appropriate term in the relevant field, as long as the same technical effect is achieved. The term "base station" is not limited to specific technical terms. It should be noted that the embodiments of this application only use the base station in the NR system as an example for introduction, and do not limit the specific type of base station.

[0054] Core network equipment, also known as core network nodes, core network functions, or core network elements, includes, but is not limited to, at least one of the following: Mobility Management Entity (MME), Access and Mobility Management Function (AMF), Session Management Function (SMF), User Plane Function (UPF), Policy Control Function (PCF), Policy and Charging Rules Function (PCRF), Edge Application Server Discovery Function (EASDF), Unified Data Management (UDM), Unified Data Repository (UDR), Home Subscriber Server (HSS), Centralized network configuration (CNC), Network Repository Function (NRF), Network Exposure Function (NEF), Local NEF (L-NEF), and Binding Support. Functions include BSF, Application Function (AF), Location Management Function (LMF), Gateway Mobile Location Centre (GMLC), Network Data Analytics Function (NWDAF), and Non-Terrestrial Network (NTN) equipment (such as satellite or high altitude platform station).It should be noted that the embodiments of this application only use the core network equipment in the NR system as an example for introduction, and do not limit the specific type of core network equipment. If the name of the core network equipment mentioned in the embodiments of this application changes in subsequent protocol versions (e.g., 6G), it is also within the scope of protection of this application.

[0055] Optionally, the core network equipment can be implemented by one or more functional modules in a single device, or by multiple devices working together; this application does not specifically limit this. It is understood that the aforementioned functional modules can be network elements in hardware devices, software functional modules running on dedicated hardware, or virtualized functional modules instantiated on a platform (e.g., a cloud platform).

[0056] For ease of understanding, the following explains some aspects of the embodiments of this application:

[0057] 1. Layer 1 / Layer 2 Triggered Mobility (L1 / L2-triggered mobility, LTM)

[0058] To reduce handover latency, the 3GPP organization introduced LTM (Low-Terminal Messaging) technology in cellular wireless communication systems. The serving base station pre-configures target parameters and association numbers for N (N>=1) candidate cells to the terminal. Then, based on measurement results reported by the terminal (an optional step), L1 / L2 signaling is used to instruct the terminal to apply the target parameters and handover to a candidate cell. The association number is carried in the L1 / L2 signaling. The association number can be understood as the index information of the target parameters. For example, the association number of the target parameters for candidate cell A is 1; the association number of the target parameters for candidate cell B is 2. If the association number carried in the L1 / L2 signaling is 2, it indicates that the network notifies the terminal to apply the target parameters of candidate cell B and handover to candidate cell B.

[0059] In one related technology, LTM only supports cell handover under the same base station (the source cell and the target cell are managed by the same base station); the LTM process is as follows: Figure 2a As shown. Another related technology involves cell handover between different base stations (the source cell and the target cell are managed by different base stations).

[0060] It should be noted that a base station consists of one centralized unit (CU) and N distributed units (DU) (N is greater than or equal to 1); in a real network, it can be a single node, that is, a base station in which the functions of CU and DU are integrated into a single physical node; or it can consist of multiple nodes, that is, the functions of CU and DU are provided by different physical nodes; this application does not impose any restrictions on this.

[0061] 2. Safety requirements during the switchover process

[0062] In an NR system, RAN-side security functions include encryption / decryption, integrity protection, and integrity verification; these operations require a security key. RAN-side security functions are implemented by the Packet Data Convergence Protocol (PDCP) logical function module, which is located within the CU (Curricular Unit Control) function of the base station.

[0063] It should be noted that in this application, the key and the secret key are equivalent.

[0064] In the NR system, the UE is required to change its key when changing the serving base station or changing the CU node. That is, if the UE performs a serving cell handover that results in a change of serving base station or CU, the key used in the source base station or CU will not be transferred to the target base station or CU for continued use. However, if the UE performs a serving cell handover that does not result in a change of serving base station or CU (i.e., the source cell and the target cell are both governed by the same serving base station or CU), then it is permissible not to change the key before and after the handover.

[0065] 3. Key Derivation During the Switching Process

[0066] During the transition of related technologies, such as Figure 2b As shown, the network side can instruct the terminal to change its key via a handover command. Specifically: if the handover command includes a Next-hop Chain Counter (NCC), the terminal uses a different key than the source cell when exchanging signaling or data with the target cell; if it does not include an NCC, the terminal uses the same key as the source cell when exchanging signaling or data with the target cell.

[0067] The NCC is one of the parameters used by the terminal to derive a new key; the network side (NW) passes the NCC to the UE to ensure that the UE can use the same parameters as the network side to derive the key used by the UE in the target cell.

[0068] 4. Fast Recovery

[0069] During LTM handover, if the UE fails to hand over to the target cell after receiving the handover command (e.g., due to poor signal quality in the target cell), the UE can trigger a Radio Resource Control (RRC) connection reconstruction process. During connection reconstruction, the UE first selects a cell. If the selected cell is an LTM handover candidate cell, the UE can apply the saved configuration of that candidate cell and access the candidate cell by sending a handover completion message to the base station managing that candidate cell. This process is called the Fast recovery process.

[0070] For example, serving cell A pre-configures target parameters for candidate cells B and C for the UE; then, a handover command is used to instruct the UE to switch to cell B; if the handover to B fails, the UE performs a reconstruction process. During reconstruction, the UE first performs cell selection, choosing a suitable cell for connection reconstruction. If the selected cell is a candidate cell, such as C, because the UE already has the target parameters for C, the UE can directly apply the target parameters for cell C and send a handover completion message within C to notify the network side to switch to cell C. During Fast recovery, the UE needs to use a key that matches cell C. This application is not limited to the specific process of Fast recovery, but only focuses on the timing and method of obtaining the key that matches cell C.

[0071] Compared to the traditional RRC connection reconstruction process, the Fast Recovery process allows the UE to resume data transmission more quickly.

[0072] 5. Data encryption and integrity protection

[0073] Data encryption refers to the process where the sending end generates a cipher (such as a bit stream) based on encryption input parameters (such as a sequence number, a key, etc.); the cipher (such as a bit stream) is then used to perform operations with the original plaintext data stream (such as a bit stream) to obtain an encrypted data stream; and the receiving end, after receiving the encrypted data stream, performs the reverse operation of the sending end to obtain the decrypted data stream.

[0074] Integrity protection refers to obtaining a bitstream (MAC-I) of a preset length (e.g., 32 bits) based on input parameters (such as sequence number, key, and data to be protected). Any change in input parameters may lead to a change in the transmitted MAC-I. The sending end sends the MAC-I (called MAC-I-1) along with the data to be protected. After receiving it, the receiving end calculates the MAC-I (called MAC-I-2) based on the data to be protected. The receiving end compares MAC-I-1 and MAC-I-2. If they are the same, it is considered that the data to be protected was sent by the expected sending end and has not been tampered with, i.e., it passes the integrity check. Here, it is assumed that the attacker does not have the key; therefore, it is impossible to generate a MAC-I that matches the tampered data after tampering with the data sent by the sending end.

[0075] This application does not concern itself with the specific processes of encryption / decryption, integrity protection, or integrity protection verification; it only focuses on the methods for obtaining the keys used in the relevant processes (or the superior keys used to derive those keys).

[0076] It should be noted that under the existing mechanism, if the network-side device initiates an intra-CU (Intra-CU) or intra-BS handover, the handover command does not carry key information (such as NCC). However, if the terminal fails to perform a cell handover and selects a cell X that spans across CUs (inter-CU) or base stations (inter-BS) during the RRC connection reconstruction process, the terminal cannot perform fast recovery in that cell because it lacks available key information (such as NCC) to calculate the key for the handover cell X.

[0077] The following description, in conjunction with the accompanying drawings, details the cell handover method, apparatus, and related equipment provided in this application through some embodiments and application scenarios.

[0078] See Figure 3 , Figure 3 This is a flowchart of a cell handover method provided in an embodiment of this application, such as... Figure 3 As shown, the cell handover method includes the following steps:

[0079] Step 101: The terminal receives first information sent by the network-side device, the first information being used to generate a key;

[0080] Step 102: The terminal determines whether to perform cell handover based on the first information, based on the source cell and the target cell for cell handover.

[0081] Step 103: If the terminal performs a cell handover and the handover fails, the terminal determines whether to perform a fast recovery based on the first information during the Radio Resource Control (RRC) connection reconstruction process.

[0082] The first information may be information required to calculate the key. The first information may be parameters used to derive (or, in other words, to extrapolate) the new key. These parameters may include a next-hop chain counter (NCC) or parameters used to determine the NCC, etc., and are not limited in this embodiment. For example, the first information may be the NCC.

[0083] In addition, the first information may be carried in the handover command or other downlink signaling, and this embodiment does not limit this.

[0084] In one implementation, the terminal determines whether to perform a cell handover based on the first information, using a first identifier of the source cell and a third identifier of the target cell. The first identifier is an identifier associated with the source cell, and the third identifier is an identifier associated with the target cell. Optionally, the first identifier can be used to identify the CU or base station to which the source cell belongs, and can also be replaced by: an identifier associated with the source cell, an associated identifier of the source cell, or identifier information of the source cell, etc. The third identifier can be used to identify the CU or base station to which the target cell belongs, and can also be replaced by: an identifier associated with the target cell, an associated identifier of the target cell, or identifier information of the target cell, etc.

[0085] It should be noted that cell handover based on the first information can be understood as changing the key during cell handover; cell handover not based on the first information can be understood as not changing the key during cell handover.

[0086] In one implementation, the terminal can determine whether to perform a key change by comparing the identifier associated with the source cell and the identifier associated with the target cell. For example, the terminal can determine whether to perform a key change during cell handover by comparing the identifier associated with the source cell and the identifier associated with the target cell. If the identifier associated with the source cell and the identifier associated with the target cell are the same, no key change is performed; if the identifier associated with the source cell and the identifier associated with the target cell are different, a key change is performed.

[0087] It should be noted that the terminal's failure to perform cell handover means that the terminal failed to handover from the source cell to the target cell.

[0088] In one embodiment, if the terminal fails to perform a cell handover to the target cell, the terminal determines whether to perform a fast recovery based on the first information during the RRC connection reconstruction process.

[0089] In one embodiment, if the terminal fails to perform a cell handover to the target cell, the terminal determines whether to perform fast recovery based on the first information during the RRC connection reconstruction process, based on the source cell and the selected first cell for fast recovery.

[0090] In one implementation, if the terminal fails to perform a cell handover to the target cell, the terminal determines whether to perform fast recovery based on the first information during the RRC connection reconstruction process, based on a first identifier of the source cell and a second identifier of the selected first cell for fast recovery. The first identifier is an identifier associated with the source cell, and the second identifier is an identifier associated with the first cell. Optionally, the first identifier can be used to identify the CU or base station to which the source cell belongs, and the first identifier can also be replaced by: an identifier associated with the source cell, an associated identifier of the source cell, or identification information of the source cell, etc. The second identifier can be used to identify the CU or base station to which the first cell belongs, and the second identifier can also be replaced by: an identifier associated with the first cell, an associated identifier of the first cell, or identification information of the first cell, etc.

[0091] It should be noted that "fast recovery based on the first information" can be understood as changing the key during fast recovery; "fast recovery not based on the first information" can be understood as not changing the key during fast recovery.

[0092] In one implementation, the terminal can determine whether to perform a key change by comparing the identifier associated with the source cell and the identifier associated with the first cell. For example, the terminal can determine whether to perform a key change during fast recovery by comparing the identifier associated with the source cell and the identifier associated with the first cell. If the identifier associated with the source cell and the identifier associated with the first cell are the same, no key change is performed; if the identifier associated with the source cell and the identifier associated with the first cell are different, a key change is performed.

[0093] In one implementation, the pre-configured candidate cell configuration includes identification information A (such as a third identifier). Simultaneously, the terminal also knows the identification information B (such as a first identifier) ​​of the currently serving cell. When the terminal receives a handover command, it compares whether the identification information A associated with the target cell (one of the candidate cells) in the handover command is equal to the identification information B of the currently serving cell. If they are equal, it is considered that the handover does not require a key change; otherwise, it is considered that the handover requires a key change. In one implementation: the identification information associated with the cell is related to the CU to which the cell belongs. If the identification information associated with the cell is the same, it indicates that the source cell and the target cell are associated with the same CU, meaning that the handover does not require a key change; otherwise, a key change is required.

[0094] In one implementation, the terminal determines whether to perform cell handover based on the first information, based on the source cell and the target cell for cell handover. This may include: the terminal determining whether to generate a key based on the first information to handover to the target cell, based on the source cell and the target cell for cell handover.

[0095] In one embodiment, when the terminal performs a cell handover and the handover fails, the terminal determines whether to perform fast recovery based on the first information during the Radio Resource Control (RRC) connection reconstruction process, which includes: when the terminal fails to handover to the target cell, the terminal determines whether to generate a key based on the first information for fast recovery during the RRC connection reconstruction process.

[0096] In one implementation, the terminal determines whether to perform cell handover based on the first information, which can be understood or replaced as: the terminal determines whether to deduce a key related to the target cell based on the first information, wherein the key related to the target cell is used to encrypt or protect the signaling or data interacting between the terminal and the target cell.

[0097] In one implementation, the terminal determines whether to perform fast recovery based on the first information during the RRC connection reconstruction process. This can be understood or replaced as follows: the terminal determines whether to deduce a key related to the first cell based on the first information. The key related to the first cell is used to encrypt or protect the signaling or data interacting between the terminal and the first cell. The first cell is a cell selected by the terminal, and the first cell is used for fast recovery.

[0098] In this embodiment, regardless of whether the terminal is handovering within a CU or base station (i.e., intra-CU / intra-BS) or across CUs or base stations (i.e., inter-CU / inter-BS), the terminal can obtain key information (i.e., the first information). This solves the problem that the terminal cannot obtain the key when performing fast recovery in an inter-CU / inter-BS cell (i.e., the cell performing fast recovery and the serving cell before handover do not belong to the same CU or base station) after an intra-CU / intra-BS handover failure. Even after an intra-CU / intra-BS handover failure, when connection reconstruction is needed in a cell across CUs or base stations (i.e., inter-CU / inter-BS), the terminal can use the key generated by the first information sent by the network-side device for fast recovery, thereby reducing access latency. Furthermore, in the inter-CU / inter-BS handover scenario, the terminal can handover to the target cell based on the obtained first information; or after a handover failure, it can reconstruct the connection in a cell across CUs or base stations (i.e., inter-CU / inter-BS) based on the first information, thereby reducing access latency.

[0099] In this embodiment, the terminal receives first information sent by a network-side device, the first information being used to generate a key. The terminal determines whether to perform cell handover based on the first information, using the source cell and the target cell for cell handover. If the terminal performs cell handover and the handover fails, the terminal determines whether to perform fast recovery based on the first information during the Radio Resource Control (RRC) connection reconstruction process. In this way, the terminal can obtain and apply appropriate keys through the first information for cell handover or fast recovery, thereby successfully completing the handover process or successfully performing fast recovery after a handover failure (e.g., due to insufficient link quality between the terminal and the target cell), thus reducing access latency.

[0100] Optionally, when the terminal performs a cell handover and the handover fails, the terminal determines whether to perform fast recovery based on the first information during the RRC connection reconstruction process, including at least one of the following:

[0101] If the terminal performs a cell handover and the handover fails, and the first identifier and the second identifier do not match, the terminal determines to perform a fast recovery based on the first information during the RRC connection reconstruction process.

[0102] If the terminal performs a cell handover and the handover fails, and the first identifier matches the second identifier, then the terminal determines that it will not use the first information for fast recovery during the RRC connection reconstruction process.

[0103] Wherein, the first identifier is an identifier associated with the source cell, and the second identifier is an identifier associated with the first cell selected by the terminal, the first cell being used for fast recovery.

[0104] The mismatch between the first identifier and the second identifier can mean that the first identifier and the second identifier do not meet the preset matching conditions. For example, the mismatch between the first identifier and the second identifier can mean that the first identifier and the second identifier are not equal.

[0105] In addition, matching the first identifier and the second identifier can mean that the first identifier and the second identifier meet a preset matching condition. For example, matching the first identifier and the second identifier can mean that the first identifier and the second identifier are equal.

[0106] In one implementation, the mismatch between the first identifier and the second identifier can indicate that the source cell and the first cell are cells that cross CU or base station (i.e., inter-CU / inter-BS).

[0107] It should be noted that two cells designated as inter-CU / inter-BS refer to cells that do not belong to the same CU or base station.

[0108] In one implementation, the first identifier and the second identifier are matched to characterize the source cell and the first cell as cells within a CU or base station (i.e., intra-CU / intra-BS).

[0109] It should be noted that two cells designated as intra-CU / intra-BS refer to cells belonging to the same CU or base station.

[0110] In one implementation, the terminal does not use the first information for rapid recovery, which includes: the terminal uses the key used in the source cell for rapid recovery.

[0111] In one implementation, if the first identifier and the third identifier do not match, the terminal performs cell handover based on the first information, wherein the first identifier is an identifier associated with the source cell and the third identifier is an identifier associated with the target cell; if the terminal handover fails, and if the first identifier and the second identifier do not match, the terminal determines to perform fast recovery based on the first information during the RRC connection reconstruction process, wherein the first identifier is an identifier associated with the source cell and the second identifier is an identifier associated with the first cell selected by the terminal.

[0112] In one implementation, if the first identifier matches the third identifier, the terminal does not use the first information for cell handover, wherein the first identifier is an identifier associated with the source cell and the third identifier is an identifier associated with the target cell; if the terminal handover fails, and if the first identifier does not match the second identifier, the terminal determines to perform fast recovery based on the first information during RRC connection reconstruction, wherein the first identifier is an identifier associated with the source cell and the second identifier is an identifier associated with the first cell selected by the terminal.

[0113] In one implementation, if the first identifier and the third identifier do not match, the terminal performs cell handover based on the first information, wherein the first identifier is an identifier associated with the source cell and the third identifier is an identifier associated with the target cell; if the terminal handover fails, if the first identifier matches the second identifier, the terminal determines that it will not use the first information for fast recovery during the RRC connection reconstruction process, wherein the first identifier is an identifier associated with the source cell and the second identifier is an identifier associated with the first cell selected by the terminal.

[0114] In one implementation, if the first identifier matches the third identifier, the terminal does not use the first information for cell handover, wherein the first identifier is an identifier associated with the source cell and the third identifier is an identifier associated with the target cell; if the terminal handover fails, if the first identifier matches the second identifier, the terminal determines that it will not use the first information for fast recovery during RRC connection reconstruction, wherein the first identifier is an identifier associated with the source cell and the second identifier is an identifier associated with the first cell selected by the terminal.

[0115] In this embodiment, if the terminal performs a cell handover and the handover fails, and the first identifier and the second identifier do not match, the terminal determines to perform fast recovery based on the first information during the RRC connection reconstruction process. The first identifier is an identifier associated with the source cell, and the second identifier is an identifier associated with the first cell selected by the terminal. The mismatch between the first identifier and the second identifier can be used to indicate that the terminal needs to reconstruct the connection in a cell under inter-CU / inter-BS. Therefore, regardless of whether a handover failure has occurred in intra-CU / intra-BS or inter-CU / inter-BS, the terminal can perform fast recovery using the key generated by the first information sent by the network-side device in a cell under inter-CU / inter-BS, thereby reducing access latency.

[0116] In this embodiment, if the terminal performs a cell handover and the handover fails, and the first identifier matches the second identifier, the terminal determines that it will not use the first information for fast recovery during the RRC connection reconstruction process. The first identifier is an identifier associated with the source cell, and the second identifier is an identifier associated with the first cell selected by the terminal. Matching the first and second identifiers can be used to indicate that the terminal needs to reconstruct the connection in a cell under the intra-CU / intra-BS. The terminal can use the key used in the source cell for fast recovery, thereby reducing access latency.

[0117] Optionally, the terminal determines to perform rapid recovery based on the first information during the RRC connection reconstruction process, including:

[0118] During the RRC connection reconstruction process, the terminal generates a first key based on the first information;

[0119] The terminal uses the first key for rapid recovery.

[0120] In the event that the terminal performs a cell handover and the handover fails, if the first identifier and the second identifier do not match, the terminal uses the first key to communicate with network-side equipment (such as the CU or base station to which the first cell belongs) during fast recovery.

[0121] It should be noted that the terminal using the first key for fast recovery can mean that the terminal directly uses the first key for encryption and / or integrity protection during the fast recovery process, or that the terminal uses a key derived from the first key for encryption and / or integrity protection during the fast recovery process.

[0122] In one embodiment, the terminal uses the first key for rapid recovery, which may include: when the terminal performs rapid recovery after a handover failure, it uses the first key (or a key derived from the first key) for encryption and / or integrity protection during data transmission and reception with network-side equipment (such as the CU or base station to which the first cell belongs).

[0123] In this implementation, during the RRC connection reconstruction process, the terminal generates a first key based on the first information; the terminal then uses the first key for rapid recovery. Therefore, regardless of whether an intra-CU / intra-BS or inter-CU / inter-BS handover failure has occurred, the terminal can quickly recover using the key generated from the first information sent by the network-side equipment in the inter-CU / inter-BS cell, thereby reducing access latency.

[0124] Optionally, if the terminal determines that the first information will not be used for fast recovery during RRC connection reconstruction, the method further includes:

[0125] During the RRC connection reconstruction process, the terminal uses a second key for rapid recovery;

[0126] The second key is the key corresponding to the source cell.

[0127] In the event that the terminal performs a cell handover and the handover fails, if the first identifier matches the second identifier, the terminal uses the second key to communicate with network-side equipment (such as the CU or base station to which the first cell belongs) during fast recovery.

[0128] It should be noted that the terminal using the second key for fast recovery can mean that the terminal directly uses the second key for encryption and / or integrity protection during the fast recovery process, or that the terminal uses a key derived from the second key for encryption and / or integrity protection during the fast recovery process.

[0129] In one embodiment, the terminal uses the second key for rapid recovery, which may include: when the terminal performs rapid recovery after a handover failure, it uses the second key for encryption and / or integrity protection during data transmission and reception with network-side equipment (such as the CU or base station to which the first cell belongs).

[0130] In one embodiment, the second key is a key corresponding to the source cell, which may mean that the second key is a key used by the terminal in the source cell, or a key calculated by the terminal for communicating with the source cell.

[0131] In this implementation, during the RRC connection reconstruction process, the terminal uses a second key for rapid recovery; thus, when the terminal needs to reconstruct the connection in a cell under intra-CU / intra-BS, it can use the key used in the source cell for rapid recovery, thereby reducing access latency.

[0132] Optionally, the terminal determines whether to perform cell handover based on the first information, based on the source cell and the target cell for cell handover, including at least one of the following:

[0133] If the first identifier and the third identifier do not match, the terminal performs cell handover based on the first information;

[0134] If the first identifier matches the third identifier, the terminal does not use the first information for cell handover;

[0135] Wherein, the first identifier is an identifier associated with the source cell, and the third identifier is an identifier associated with the target cell.

[0136] The mismatch between the first identifier and the third identifier can mean that the first identifier and the third identifier do not meet the preset matching conditions. For example, the mismatch between the first identifier and the third identifier can mean that the first identifier and the third identifier are not equal.

[0137] In addition, matching the first identifier with the third identifier can mean that the first identifier and the third identifier meet preset matching conditions. For example, matching the first identifier with the third identifier can mean that the first identifier and the third identifier are equal.

[0138] In one implementation, the mismatch between the first identifier and the third identifier can characterize the source cell and the target cell as cells spanning CUs or base stations (i.e., inter-CU / inter-BS).

[0139] In one implementation, matching the first identifier with the third identifier can characterize the source cell and the target cell as cells within a CU or base station (i.e., intra-CU / intra-BS).

[0140] In one implementation, the terminal does not use the first information to perform cell handover, including: the terminal uses the key used in the source cell to perform cell handover.

[0141] In this embodiment, if the first identifier and the third identifier do not match, the terminal performs cell handover based on the first information. The first identifier is an identifier associated with the source cell, and the third identifier is an identifier associated with the target cell. The mismatch between the first identifier and the third identifier can be used to indicate that the terminal needs to perform cell handover under inter-CU / inter-BS, so that the terminal can perform cell handover using the key generated by the first information sent by the network-side device under inter-CU / inter-BS, avoiding the need for the terminal to determine whether to perform cell handover based on the first information by whether the handover command carries the first information (i.e., key information).

[0142] In this embodiment, if the first identifier matches the third identifier, the terminal does not use the first information for cell handover. The first identifier is an identifier associated with the source cell, and the third identifier is an identifier associated with the target cell. Matching the first and third identifiers can be used to indicate that the terminal needs to perform cell handover under intra-CU / intra-BS, thus enabling the terminal to use the key used in the source cell for cell handover under intra-CU / intra-BS. This avoids the terminal needing to determine whether to perform cell handover based on the first information by checking whether the handover command carries the first information (i.e., key information).

[0143] Optionally, the terminal performs cell handover based on the first information, including:

[0144] The terminal generates a third key based on the first information;

[0145] The terminal uses the third key to perform cell handover.

[0146] In the case where the first identifier and the third identifier do not match, the terminal uses the third key to communicate with network-side equipment (such as the CU or base station to which the target cell belongs) when performing cell handover.

[0147] It should be noted that the terminal using the third key for cell handover can mean that the terminal directly uses the third key for encryption and / or integrity protection during the cell handover process, or that the terminal uses a key derived from the third key for encryption and / or integrity protection during the cell handover process.

[0148] In one embodiment, the terminal uses the third key for cell handover, which may include: during cell handover, the terminal uses the third key for encryption and / or integrity protection during data transmission and reception with network-side equipment (such as the CU or base station to which the target cell belongs).

[0149] In this implementation, if the first identifier and the third identifier do not match, the terminal generates a third key based on the first information, and the terminal uses the third key to perform cell handover. Thus, the terminal can perform cell handover using the key generated from the first information sent by the network-side device under inter-CU / inter-BS conditions, avoiding the need for the terminal to determine whether to perform cell handover based on the first information by checking whether the handover command carries the first information (i.e., key information).

[0150] Optionally, if the terminal does not use the first information for cell handover, the method further includes:

[0151] The terminal uses a second key to perform cell handover, wherein the second key is a key corresponding to the source cell.

[0152] Wherein, if the terminal does not use the first information to perform cell handover, the terminal uses the second key to communicate with network-side equipment (such as the CU or base station to which the target cell belongs) when performing cell handover.

[0153] It should be noted that the terminal using the second key for cell handover can mean that the terminal directly uses the second key for encryption and / or integrity protection during the cell handover process, or that the terminal uses a key derived from the second key for encryption and / or integrity protection during the cell handover process.

[0154] In one embodiment, the terminal uses a second key for cell handover, which may include: during cell handover, the terminal uses the second key for encryption and / or integrity protection during data transmission and reception with network-side equipment (such as the target cell).

[0155] In this embodiment, when the first identifier matches the third identifier, the terminal uses the second key to perform cell handover. This allows the terminal to use the key used in the source cell for cell handover under intra-CU / intra-BS, avoiding the need for the terminal to determine whether to perform cell handover based on the first information by checking whether the handover command carries the first information (i.e., key information).

[0156] Optionally, the first information is the next hop chain counter (NCC).

[0157] In this implementation, the terminal can obtain the NCC-generated key for rapid recovery. Even after experiencing an intra-CU / intra-BS handover failure, when connection reconstruction is required in an inter-CU / inter-BS cell, the terminal can use the NCC-generated key sent by the network-side device for rapid recovery, thereby reducing access latency.

[0158] Optionally, the first information is carried by the switching command.

[0159] In this implementation, the terminal can obtain the first information generated key through the handover command for rapid recovery. Even after experiencing an intra-CU / intra-BS handover failure, when connection reconstruction is required in an inter-CU / inter-BS cell, the terminal can use the first information generated by the handover command to quickly recover, thus expanding the applicable scenarios for rapid recovery and improving the user experience.

[0160] Optionally, the method further includes:

[0161] If the terminal performs a cell handover and the handover is successful, the terminal discards the first information.

[0162] In this embodiment, when the terminal performs a cell handover and the handover is successful, the terminal discards the first information, thereby reducing the terminal's memory overhead.

[0163] Optionally, the method further includes:

[0164] If the terminal determines that it cannot quickly restore the connection during the RRC connection reconstruction process, the terminal sends a request message to the network-side device, the request message being used to request connection reconstruction.

[0165] In one implementation, the terminal performs cell handover based on the first information;

[0166] If the terminal performs a cell handover and the handover fails, and if the terminal determines that it cannot quickly recover during the RRC connection reconstruction process, the terminal sends a request message to the network-side device to request connection reconstruction.

[0167] In related technologies, during handover (HO) operations, the terminal changes its key. If the handover fails, the terminal may need to use the source key during fast recovery, but it cannot revert to using the source key. Therefore, the terminal cannot restore the connection based on the fast recovery procedure. For example, before cell handover, the UE uses key 1; during cell handover, the UE changes its key to key 2; after cell handover failure, the UE needs to use the source key (key 1) during fast recovery. If, due to implementation limitations, the UE cannot revert to key 1 for fast recovery, the terminal cannot restore the connection based on the fast recovery procedure. In this embodiment, the terminal sends a request message to the network-side device to re-establish the connection, and the network-side device instructs the terminal to use a new key (key 3) for connection reconstruction.

[0168] In this embodiment, if the terminal performs a cell handover and the handover fails, and the terminal determines that it cannot quickly recover during the RRC connection reconstruction process, the terminal sends a request message to the network-side device. The request message is used to request connection reconstruction, so that even if it cannot quickly recover, the terminal can still achieve connection reconstruction through the request message.

[0169] In this embodiment of the application, taking NCC as the first information as an example, the network-side device can carry parameters (such as NCC) for the terminal to deduce a new key in the downlink signaling (such as a handover command, or other downlink signaling besides the handover command); the terminal saves the NCC; after receiving the handover command, the terminal determines whether it needs to deduce a new key based on the source cell and the target cell indicated by the handover command; if it does not need to deduce a new key (assuming it is an intra-BS handover, therefore, it does not need to deduce a new key), the terminal attempts to hand over to the target cell using the current key; if the cell handover fails, the terminal performs RRC connection reconstruction; if the reconstructed cell is a pre-configured handover candidate cell, the terminal re-determines whether it needs to deduce a new key; if it needs to deduce a new key, the terminal performs key deduction based on the received NCC and attempts to hand over to the target cell based on the new key.

[0170] The following examples will provide further explanation:

[0171] Example 1:

[0172] This example describes the process of a switch command instructing an intra-CU switch and performing fast recovery in the inter-CU cell.

[0173] Cell handover methods include the following process:

[0174] (1) The UE receives pre-configuration information from the serving cell (Cell) A. The pre-configuration information includes the target cell configuration required for the UE to switch to the candidate cell. The pre-configuration information includes two sets of candidate cell configurations, corresponding to candidate cells B and C respectively. Wherein: Cell A and Cell B are cells under the same CU or base station; Cell A and Cell C are cells under different CUs or base stations.

[0175] (2) The UE receives parameters (e.g., NCC) from the first downlink signaling for the UE to deduce the new key, and the UE saves the NCC;

[0176] (3) After receiving the second downlink signaling (i.e., the handover command), the UE determines whether it needs to deduce a new key based on the source cell and the target cell indicated by the handover command; for example, if the target cell is Cell B, then it does not need to deduce a new key.

[0177] It should be noted that the first downlink signaling can be a signaling that precedes the second downlink signaling, or the first downlink signaling and the second downlink signaling can be the same signaling.

[0178] (4) The UE attempts to switch to the target cell using the current key.

[0179] (5) If a handover failure occurs, the UE performs cell selection (the cell selection process is a step in the RRC connection re-establishment process). If the selected cell is a pre-configured candidate cell (such as Cell C), the UE determines whether a new key needs to be derived based on the source cell and the selected cell.

[0180] For example, the UE selects Cell C. Since Cell A and Cell C do not belong to the same CU or cell under the jurisdiction of the base station, the UE determines that a new key needs to be derived.

[0181] (7) The UE derives a new key based on the NCC obtained in step (2). The UE attempts to switch to Cell C based on the new key (i.e., perform fast recovery in Cell C).

[0182] Example 2:

[0183] This example describes the process of a switch command instructing an intra-CU switch and performing fast recovery in the intra-CU cell.

[0184] Cell handover methods include the following process:

[0185] (1) The UE receives pre-configuration information from serving cell A. The pre-configuration information includes the target cell configuration required for the UE to switch to the candidate cell. The pre-configuration information includes two sets of candidate cell configurations, corresponding to candidate cells B and C respectively. Wherein: Cell A, Cell B, and Cell C are cells under the same CU or base station.

[0186] (2) The UE receives parameters (e.g., NCC) from the first downlink signaling for the UE to deduce the new key, and the UE saves the NCC;

[0187] (3) After receiving the second downlink signaling (i.e., the handover command), the UE determines whether it needs to deduce a new key based on the source cell and the target cell indicated by the handover command; for example, if the target cell is Cell B, then it does not need to deduce a new key.

[0188] It should be noted that the first downlink signaling can be a signaling that precedes the second downlink signaling, or the first downlink signaling and the second downlink signaling can be the same signaling.

[0189] (4) The UE attempts to switch to the target cell using the current key.

[0190] (5) If a handover failure occurs, the UE performs cell selection. If the cell selected by the UE is a pre-configured candidate cell (e.g., Cell C)...

[0191] The UE determines whether a new key needs to be derived based on the source cell and the selected cell. For example, if the UE selects Cell C, since Cell A and Cell C belong to the same CU or base station, the UE determines that a new key does not need to be derived.

[0192] (6) The UE attempts to switch to Cell C based on the current key (i.e., perform fast recovery in Cell C).

[0193] Example 3:

[0194] This example describes the process of a switch command instructing an inter-CU switch and performing fast recovery in the inter-CU cell.

[0195] Cell handover methods include the following process:

[0196] (1) The UE receives pre-configuration information from serving cell A. The pre-configuration information includes the target cell configuration required for the UE to switch to the candidate cell. The pre-configuration information includes two sets of candidate cell configurations, corresponding to candidate cells B and C respectively. Among them, Cell A and Cell B are cells under different CUs or base stations, and Cell A and Cell C are also cells under different CUs or base stations.

[0197] (2) The UE receives parameters (e.g., NCC) from the first downlink signaling for the UE to deduce the new key, and the UE saves the NCC;

[0198] (3) After receiving the second downlink signaling (i.e., the handover command), the UE determines whether it needs to deduce a new key based on the source cell and the target cell indicated by the handover command; for example, if the target cell is Cell B, then it needs to deduce a new key.

[0199] It should be noted that the first downlink signaling can be a signaling that precedes the second downlink signaling, or the first downlink signaling and the second downlink signaling can be the same signaling.

[0200] (4) Based on the NCC obtained in step (2), the UE derives a new key X and attempts to switch to the target cell using the new key X.

[0201] (5) If a handover failure occurs, the UE performs cell selection. If the selected cell is a pre-configured candidate cell (such as Cell C), the UE determines whether a new key needs to be derived based on the source cell and the selected cell. For example, if the UE selects Cell C, since Cell A and Cell C do not belong to the same CU or base station, the UE determines that a new key needs to be derived.

[0202] (6) Based on the NCC obtained in step (2), the UE derives a new key Y. The UE attempts to switch to Cell C based on the new key Y (i.e., perform fast recovery in Cell C). It should be noted that the derived key also requires the parameters of the target cell; therefore, X and Y are different.

[0203] Example 4:

[0204] This example describes the process of a switch command instructing an inter-CU switch and performing fast recovery in the intra-CU cell.

[0205] Cell handover methods include the following process:

[0206] (1) The UE receives pre-configuration information from serving cell A. The pre-configuration information includes the target cell configuration required for the UE to switch to the candidate cell. The pre-configuration information includes two sets of candidate cell configurations, corresponding to candidate cells B and C respectively. Wherein: Cell A and Cell C are cells under the same CU or base station; Cell A and Cell B are cells under different CUs or base stations.

[0207] (2) The UE receives parameters (e.g., NCC) from the first downlink signaling for the UE to deduce the new key, and the UE saves the NCC;

[0208] (3) After receiving the second downlink signaling (i.e., the handover command), the UE determines whether it needs to deduce a new key based on the source cell and the target cell indicated by the handover command; for example, if the target cell is Cell B, then it needs to deduce a new key.

[0209] It should be noted that the first downlink signaling can be a signaling that precedes the second downlink signaling, or the first downlink signaling and the second downlink signaling can be the same signaling.

[0210] (4) The UE saves the current key (hereinafter referred to as the old key); based on the NCC obtained in step (2), the UE derives the new key and attempts to switch to the target cell using the new key.

[0211] (5) If a handover failure occurs, the UE performs cell selection. If the selected cell is a pre-configured candidate cell (such as Cell C), the UE determines whether a new key needs to be derived based on the source cell and the selected cell. For example, if the UE selects Cell C, since Cell A and Cell C belong to the same CU or base station, the UE determines that a new key does not need to be derived.

[0212] (6) The UE uses the old key saved in step (4). The UE attempts to switch to Cell C based on the old key (i.e., perform fast recovery in Cell C).

[0213] Example 5:

[0214] This example describes the process of a switch command instructing an inter-CU switch and performing fast recovery in the intra-CU cell.

[0215] Cell handover methods include the following process:

[0216] Steps (1) to (5) are the same as in Example 4;

[0217] Step (6) When the UE determines that it needs to fall back to the old key, the UE does not use the fast recovery process to switch to Cell C, but instead performs connection recovery in Cell C by sending a connection recovery request (i.e., fast recovery is not performed, which is applicable when the UE cannot fall back to the old key).

[0218] In the above embodiments, NCC is an optional configuration. If the network-side device does not send NCC to the UE, when the UE selects a cell, if it finds that the selected cell is a pre-configured candidate cell, but the selected cell and the source serving cell are inter-CU or inter-BS cells, or the association identifier of the selected cell and the source serving cell do not match, then the UE determines that fast recovery cannot be performed and continues to perform RRC connection reconstruction.

[0219] It should be noted that this application uses LTM as an example for illustration, but the scheme of this application is applicable to the fast recovery process of all pre-configured candidate cell handover types; for example, it is applicable to CHO, CPAC, CLTM, etc.

[0220] Through the embodiments of this application, the UE can obtain key deduction parameters during the handover process; and accurately identify when to perform key deduction and obtain a new key; in addition, the embodiments of this application expand the applicable scenarios of fast recovery and improve the user experience.

[0221] This application also provides a cell handover method, including:

[0222] The terminal received the handover command;

[0223] The terminal determines whether to perform cell handover based on the first information;

[0224] If, when it is determined that a cell handover should be performed based on the first information, the terminal has no available first information, then the terminal performs a target operation, which includes at least one of the following:

[0225] Cell handover failure confirmed;

[0226] Ignore the toggle command;

[0227] Trigger the RRC connection reconstruction process.

[0228] In one implementation, when a cell handover is triggered on the terminal, the terminal determines that a cell handover needs to be performed based on first information, based on the source cell and the target cell for the cell handover; and if the terminal has no available first information (i.e., the terminal has not received the first information), then the terminal performs the target operation.

[0229] In one embodiment, the fact that the terminal has no available first information may mean that the handover command does not carry the first information; or that the terminal is not configured with the first information for the cell handover process corresponding to the handover command.

[0230] In one implementation, the terminal ignores the handover command, which can be considered as the terminal not performing a handover.

[0231] In one implementation, the terminal performing the target operation may include the terminal believing it has been attacked and triggering an RRC connection reconstruction process.

[0232] In one implementation, the terminal can determine whether to perform cell handover based on the first information based on the instruction of the handover command.

[0233] In one implementation, the terminal can determine whether to perform cell handover based on the first information, based on the source cell and the target cell for cell handover. It should be noted that the specific implementation of the terminal determining whether to perform cell handover based on the first information, based on the source cell and the target cell for cell handover, can be found in the description of the foregoing embodiments; to avoid repetition, it will not be repeated here.

[0234] It should be noted that the specific implementation of cell handover based on the first information can be found in the description of the foregoing embodiments, and will not be repeated here to avoid repetition.

[0235] It should be noted that the first information can be referred to the description of the foregoing embodiments, and will not be repeated here to avoid repetition.

[0236] In related technologies, when a terminal receives a handover command that requires the terminal to change its key, but the network-side device does not provide the first information for deriving the new key, the terminal may wait indefinitely for the first information, leading to abnormal terminal operation.

[0237] The embodiments of this application can clarify the terminal's behavior when the terminal receives a handover command that requires the terminal to change the key, but the network-side device does not provide the first information for deriving the new key.

[0238] In this embodiment of the application, if the terminal has no available first information when it is determined that cell handover is to be performed based on the first information, the terminal determines that the cell handover has failed or ignores the handover command or triggers the RRC connection reconstruction process, thereby enabling the terminal to recover after receiving an erroneous network handover signaling; and a method for recovering the terminal after it has been attacked is provided.

[0239] The following example illustrates this:

[0240] Example 6:

[0241] This example describes a switching command instructing an inter-CU switch, during which the terminal is not configured with parameters for a new key.

[0242] Cell handover methods include the following process:

[0243] (1) The UE receives pre-configuration information from serving cell A. The pre-configuration information includes the target cell configuration required for the UE to switch to the candidate cell. The pre-configuration information includes two sets of candidate cell configurations, corresponding to candidate cells B and C respectively. Among them, Cell A and Cell B are cells under different CUs or base stations, and Cell A and Cell C are also cells under different CUs or base stations.

[0244] (2) After receiving the second downlink signaling (i.e., the handover command), the UE determines whether it needs to deduce a new key based on the source cell and the target cell indicated by the handover command; for example, if the target cell is Cell B, then it needs to deduce a new key.

[0245] It should be noted that the second downlink signaling does not provide parameters for the UE to derive the new key (such as NCC); before receiving the second downlink signaling, the UE also did not receive parameters for deriving the new key that can be used for this handover.

[0246] (3) The UE ignores the received handover command or performs RRC connection reconstruction.

[0247] Because the UE did not receive the parameters to derive the new key that can be used for this handover, it cannot obtain the new key required for this handover; therefore, the terminal ignores the handover command or triggers the RRC connection reconstruction process to attempt to restore the connection.

[0248] See Figure 4 , Figure 4 This is a flowchart of a cell handover method provided in an embodiment of this application, such as... Figure 4 As shown, the cell handover method includes the following steps:

[0249] Step 201: The network-side device sends a handover command to the terminal. The handover command is used to indicate the target cell for handover, and the handover command carries first information.

[0250] During the process of the terminal switching to the target cell, the network-side device communicates with the terminal using a second key, which is a key corresponding to the source cell;

[0251] The first information is used for rapid recovery after the terminal fails to switch over.

[0252] The target cell and the source cell are cells under the jurisdiction of the network-side device.

[0253] In this embodiment, the network-side device and the terminal in the access source cell transmit and receive data, and the data transmission and reception are encrypted and / or protected for integrity using a second key; the network-side device sends a handover command to the terminal, the handover command being used to indicate the target cell for handover and carrying first information, the first information being used to generate a first key; the network-side device receives an uplink message sent by the terminal in the target cell, and decrypts and / or verifies the integrity of the uplink message using the second key; the first information is not used in the process of generating the second key; the uplink message is used to indicate that the handover is complete; the first information is optional for the terminal to use for rapid recovery after a handover failure.

[0254] It should be noted that using a second key for encryption and / or integrity protection may include using one or more keys generated based on the second key for encryption and / or integrity protection.

[0255] It should be noted that this embodiment is as a comparison with... Figure 3 The implementation methods of the network-side devices shown in the embodiments can be found in the following examples. Figure 3 The related descriptions of the embodiments shown are not repeated here to avoid repetition.

[0256] The cell handover method provided in this application can be executed by a cell handover device. This application uses the example of a cell handover device executing the cell handover method to illustrate the cell handover apparatus provided in this application.

[0257] This application provides a cell handover device. As an example, the cell handover device can be a communication device or a component within a communication device, such as a chip. The communication device can be a terminal, a network-side device, or a server, etc. Exemplarily, the terminal can be, but is not limited to, the type of terminal 11 listed above, and the network-side device can be, but is not limited to, the type of network-side device 12 listed above. This application does not impose specific limitations.

[0258] The cell handover device includes a receiving module, a transmitting module, and a processing module. These modules can be implemented in software or hardware. When implemented in hardware, the processing module can be implemented by a processor. For example, the processor can include general-purpose processors, special-purpose processors, etc., such as a Central Processing Unit (CPU), microprocessor, Digital Signal Processor (DSP), Artificial Intelligence (AI) processor, Graphics Processing Unit (GPU), Application Specific Integrated Circuit (ASIC), Network Processor (NP), Field Programmable Gate Array (FPGA), or other programmable logic devices, gate circuits, transistors, discrete hardware components, etc. The receiving and transmitting modules can be implemented by a communication interface, which can include one or more of the following: transceiver, pins, circuits, bus, radio frequency unit, etc.

[0259] For details, see Figure 5 When the cell handover device is a terminal or a component within a terminal, the cell handover device 300 includes:

[0260] The receiving module 301 is used to receive first information sent by the network-side device, wherein the first information is used to generate a key;

[0261] Processing module 302 is used to determine whether to perform cell handover based on the first information, based on the source cell and the target cell for cell handover.

[0262] The processing module 302 is further configured to determine whether to perform rapid recovery based on the first information during the Radio Resource Control (RRC) connection reconstruction process when the terminal performs cell handover and the handover fails.

[0263] Optionally, the processing module is specifically used for at least one of the following:

[0264] If the terminal performs a cell handover and the handover fails, and the first identifier and the second identifier do not match, then it is determined that a fast recovery will be performed based on the first information during the RRC connection reconstruction process.

[0265] If the terminal performs a cell handover and the handover fails, and the first identifier matches the second identifier, then it is determined that the first information will not be used for fast recovery during the RRC connection reconstruction process.

[0266] Wherein, the first identifier is an identifier associated with the source cell, and the second identifier is an identifier associated with the first cell selected by the terminal, the first cell being used for fast recovery.

[0267] Optionally, the processing module is specifically used for:

[0268] If the terminal performs a cell handover and the handover fails, and if the first identifier and the second identifier do not match, then during the RRC connection reconstruction process, the terminal generates a first key based on the first information.

[0269] The terminal uses the first key for rapid recovery.

[0270] Optionally, if the terminal determines that the first information will not be used for fast recovery during RRC connection reconstruction, the processing module is further configured to:

[0271] During RRC connection reconstruction, a second key is used for rapid recovery;

[0272] The second key is the key corresponding to the source cell.

[0273] Optionally, the processing module is specifically used for at least one of the following:

[0274] If the first identifier and the third identifier do not match, cell handover is performed based on the first information;

[0275] If the first identifier matches the third identifier, the first information is not used for cell handover.

[0276] Wherein, the first identifier is an identifier associated with the source cell, and the third identifier is an identifier associated with the target cell.

[0277] Optionally, the processing module is specifically used for:

[0278] If the first identifier and the third identifier do not match, a third key is generated based on the first information;

[0279] Cell handover is performed using the third key.

[0280] Optionally, if the terminal does not use the first information for cell handover, the processing module is further configured to:

[0281] Cell handover is performed using a second key, wherein the second key is the key corresponding to the source cell.

[0282] Optionally, the first information is the next hop chain counter (NCC).

[0283] Optionally, the first information is carried by the switching command.

[0284] Optionally, the processing module is further configured to:

[0285] If the terminal performs a cell handover and the handover is successful, the first information is discarded.

[0286] Optionally, the processing module is further configured to:

[0287] If the terminal determines that it cannot quickly restore the connection during the RRC connection reconstruction process, it sends a request message to the network-side device, which is used to request connection reconstruction.

[0288] See Figure 6 When the cell handover device is a network-side device or a component of a network-side device, the cell handover device 400 includes:

[0289] The sending module 401 is used to send a handover command to the terminal. The handover command is used to indicate the target cell for handover, and the handover command carries first information.

[0290] During the process of the terminal switching to the target cell, the network-side device communicates with the terminal using a second key, which is a key corresponding to the source cell;

[0291] The first information is used for rapid recovery after the terminal fails to switch over.

[0292] The cell handover device provided in this application embodiment can achieve... Figures 3 to 4 The various processes implemented in the method embodiments achieve the same technical effect, and will not be described again here to avoid repetition.

[0293] like Figure 7 As shown in the illustration, this application also provides a communication device 500, including a processor 501 and a memory 502. The memory 502 stores programs or instructions that can run on the processor 501. For example, when the communication device 500 is a terminal, the program or instructions executed by the processor 501 implement the various steps of the above-described cell handover method embodiment and achieve the same technical effect. When the communication device 500 is a network-side device, the program or instructions executed by the processor 501 implement the various steps of the above-described cell handover method embodiment and achieve the same technical effect. To avoid repetition, further details are omitted here.

[0294] This application embodiment also provides a terminal, including 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, for example... Figure 3 The steps in the method embodiment shown are illustrated. This terminal embodiment corresponds to the above-described terminal-side method embodiment. All implementation processes and methods of the above-described method embodiments can be applied to this terminal embodiment and achieve the same technical effect. The terminal can be... Figure 5 The cell handover device shown. Specifically, Figure 8 A schematic diagram of the hardware structure of a terminal to implement an embodiment of this application.

[0295] The terminal 600 includes, but is not limited to, at least some of the following components: radio frequency unit 601, network module 602, audio output unit 603, input unit 604, sensor 605, display unit 606, user input unit 607, interface unit 608, memory 609, and processor 610.

[0296] Those skilled in the art will understand that the terminal 600 may also include a power supply (such as a battery) for supplying power to various components. The power supply may be logically connected to the processor 610 through a power management system, thereby enabling functions such as managing charging, discharging, and power consumption through the power management system. Figure 8 The terminal structure shown does not constitute a limitation on 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 elaborated here.

[0297] It should be understood that, in this embodiment, the input unit 604 may include a graphics processor 6041 and a microphone 6042. The graphics processor 6041 processes image data of still images or videos obtained by an image capture device (such as a camera) in video capture mode or image capture mode. The display unit 606 may include a display panel 6061, which may be configured in the form of a liquid crystal display, an organic light-emitting diode, or the like. The user input unit 607 includes at least one of a touch panel 6071 and other input devices 6072. The touch panel 6071 is also called a touch screen. The touch panel 6071 may include two parts: a touch detection device and a touch controller. Other input devices 6072 may include, but are not limited to, a physical keyboard, function keys (such as volume control buttons, power buttons, etc.), a trackball, a mouse, and a joystick, which will not be described in detail here.

[0298] In this embodiment, after receiving downlink data from the network-side device, the radio frequency unit 601 can transmit it to the processor 610 for processing; in addition, the radio frequency unit 601 can send uplink data to the network-side device. Typically, the radio frequency unit 601 includes, but is not limited to, antennas, amplifiers, transceivers, couplers, low-noise amplifiers, duplexers, etc.

[0299] The memory 609 can be used to store software programs or instructions, as well as various data. The memory 609 may primarily include a first storage area for storing programs or instructions and a second storage area for storing data. The first storage area may store the operating system, application programs or instructions required for at least one function (such as sound playback, image playback, etc.). Furthermore, the memory 609 may include volatile memory or non-volatile memory. The non-volatile memory may be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. Volatile memory can be random access memory (RAM), static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDRSDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous link dynamic random access memory (SLDRAM), and direct memory bus RAM (DRRAM). The memory 609 in this embodiment includes, but is not limited to, these and any other suitable types of memory.

[0300] Processor 610 may include one or more processing units; optionally, processor 610 integrates an application processor and a modem processor, wherein the application processor mainly handles operations involving the operating system, user interface, and applications, and the modem processor mainly handles wireless communication signals, such as a baseband processor. It is understood that the aforementioned modem processor may also not be integrated into processor 610.

[0301] The radio frequency unit 601 is used to: receive first information sent by the network side device, wherein the first information is used to generate a key;

[0302] Processor 610 is configured to determine, based on source cell and target cell for cell handover, whether to perform cell handover based on the first information;

[0303] The processor 610 is further configured to determine, in the event that the terminal is performing a cell handover and the handover fails, whether to perform fast recovery based on the first information during the Radio Resource Control (RRC) connection reconstruction process.

[0304] It is understood that the implementation process of each implementation method mentioned in this embodiment can be referred to the method embodiment. Figure 3 The relevant descriptions and the achievement of the same or corresponding technical effects will not be repeated here to avoid duplication.

[0305] This application embodiment also provides a network-side device, including 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, for example... Figure 4 The steps of the method embodiment shown are illustrated. This network-side device embodiment corresponds to the above-described network-side device method embodiment. All implementation processes and methods of the above-described method embodiments can be applied to this network-side device embodiment and can achieve the same technical effect.

[0306] Specifically, embodiments of this application also provide a network-side device, which can be... Figure 6 The cell handover device shown. Figure 9 As shown, the network-side device 700 includes: an antenna 701, a radio frequency (RF) device 702, a baseband device 703, a processor 704, and a memory 705. The antenna 701 is connected to the RF device 702. In the uplink direction, the RF device 702 receives information through the antenna 701 and transmits the received information to the baseband device 703 for processing. In the downlink direction, the baseband device 703 processes the information to be transmitted and sends it to the RF device 702. The RF device 702 processes the received information and transmits it through the antenna 701.

[0307] The method executed by the network-side device in the above embodiments can be implemented in the baseband device 703, which includes a baseband processor.

[0308] The baseband device 703 may, for example, include at least one baseband board on which multiple chips are disposed, such as... Figure 9 As shown, one of the chips is, for example, a baseband processor, which is connected to the memory 705 via a bus interface to call the program or instructions in the memory 705 to execute the network-side device operations shown in the above method embodiments.

[0309] The network-side device may also include a network interface 706, such as a Common Public Radio Interface (CPRI).

[0310] The radio frequency device 702 is used for:

[0311] A handover command is sent to the terminal, the handover command being used to indicate the target cell for handover, and the handover command carrying first information;

[0312] During the process of the terminal switching to the target cell, the network-side device communicates with the terminal using a second key, which is a key corresponding to the source cell;

[0313] The first information is used for rapid recovery after the terminal fails to switch over.

[0314] Furthermore, the network-side device 700 in this application embodiment also includes: a program or instructions stored in a memory 705 and executable on a processor 704, wherein the processor 704 calls the program or instructions in the memory 705 to execute. Figure 6 The methods executed by each module shown achieve the same technical effect, and to avoid repetition, they will not be described in detail here.

[0315] Specifically, embodiments of this application also provide a network-side device. For example... Figure 10 As shown, the network-side device 800 includes: a processor 801, a network interface 802, and a memory 803. This network-side device can be... Figure 6 The cell handover device shown is an example of a common public radio interface (CPRI). The network interface 802 is, for example, a CPRI.

[0316] Network interface 802 is used for:

[0317] A handover command is sent to the terminal, the handover command being used to indicate the target cell for handover, and the handover command carrying first information;

[0318] During the process of the terminal switching to the target cell, the network-side device communicates with the terminal using a second key, which is a key corresponding to the source cell;

[0319] The first information is used for rapid recovery after the terminal fails to switch over.

[0320] Furthermore, the network-side device 800 in this embodiment of the application also includes: a program or instructions stored in a memory 803 and executable on a processor 801, wherein the processor 801 calls the program or instructions in the memory 803 to execute. Figure 6 The methods executed by each module shown achieve the same technical effect, and to avoid repetition, they will not be described in detail here.

[0321] This application also provides a readable storage medium storing a program or instructions. When the program or instructions are executed by a processor, they implement the various processes of the above-described cell handover method embodiments and achieve the same technical effect. To avoid repetition, they will not be described again here.

[0322] The processor mentioned above is either the processor in the terminal described in the above embodiments or the processor in the network-side device. The readable storage medium includes computer-readable storage media, such as computer read-only memory (ROM), random access memory (RAM), magnetic disk, or optical disk. In some examples, the readable storage medium may be a non-transient readable storage medium.

[0323] This application embodiment also provides a chip, which includes a processor and a communication interface. The communication interface and the processor are coupled. The processor is used to run programs or instructions to implement the various processes of the above-described cell handover method embodiments and can achieve the same technical effect. To avoid repetition, it will not be described again here.

[0324] It should be understood that the chip mentioned in the embodiments of this application may also be referred to as a system-on-a-chip, system chip, chip system, or system-on-a-chip, etc.

[0325] This application also provides a computer program / program product, which is stored in a storage medium and executed by at least one processor to implement the various processes of the above-described cell handover method embodiments, and can achieve the same technical effect. To avoid repetition, it will not be described again here.

[0326] This application also provides a wireless communication system, including: a terminal and a network-side device, wherein the terminal can be used to perform the steps of the cell handover method applied to the terminal as described above, and the network-side device can be used to perform the steps of the cell handover method applied to the network-side device as described above.

[0327] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. Furthermore, it should be noted that the scope of the methods and apparatuses in the embodiments of this application is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.

[0328] From the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of computer software products plus necessary general-purpose hardware platforms, and of course, they can also be implemented by hardware. The computer software product is stored in a storage medium (such as ROM, RAM, magnetic disk, optical disk, etc.), and the computer software product includes several instructions to cause the terminal or network-side device to execute the methods described in the various embodiments of this application.

[0329] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other implementations under the guidance of this application without departing from the spirit and scope of the claims. All of these implementations are within the protection scope of this application.

Claims

1. A cell handover method, characterized in that, include: The terminal receives first information sent by the network-side device, and the first information is used to generate a key; The terminal determines whether to perform cell handover based on the first information, based on the source cell and the target cell for cell handover. If the terminal performs a cell handover and the handover fails, the terminal determines whether to perform a fast recovery based on the first information during the Radio Resource Control (RRC) connection reconstruction process.

2. The method according to claim 1, characterized in that, In the event that the terminal performs a cell handover and the handover fails, the terminal determines whether to perform fast recovery based on the first information during the RRC connection reconstruction process, including at least one of the following: If the terminal performs a cell handover and the handover fails, and the first identifier and the second identifier do not match, the terminal determines to perform a fast recovery based on the first information during the RRC connection reconstruction process. If the terminal performs a cell handover and the handover fails, and the first identifier matches the second identifier, then the terminal determines that it will not use the first information for fast recovery during the RRC connection reconstruction process. Wherein, the first identifier is an identifier associated with the source cell, and the second identifier is an identifier associated with the first cell selected by the terminal, the first cell being used for fast recovery.

3. The method according to claim 2, characterized in that, The terminal determines to perform rapid recovery based on the first information during the RRC connection reconstruction process, including: During the RRC connection reconstruction process, the terminal generates a first key based on the first information; The terminal uses the first key for rapid recovery.

4. The method according to claim 2 or 3, characterized in that, If the terminal determines that the first information will not be used for rapid recovery during RRC connection reconstruction, the method further includes: During the RRC connection reconstruction process, the terminal uses a second key for rapid recovery; The second key is the key corresponding to the source cell.

5. The method according to any one of claims 1-4, characterized in that, The terminal determines whether to perform cell handover based on the first information, based on the source cell and the target cell for cell handover, including at least one of the following: If the first identifier and the third identifier do not match, the terminal performs cell handover based on the first information; If the first identifier matches the third identifier, the terminal does not use the first information for cell handover; Wherein, the first identifier is an identifier associated with the source cell, and the third identifier is an identifier associated with the target cell.

6. The method according to claim 5, characterized in that, The terminal performs cell handover based on the first information, including: The terminal generates a third key based on the first information; The terminal uses the third key to perform cell handover.

7. The method according to claim 5 or 6, characterized in that, If the terminal does not use the first information for cell handover, the method further includes: The terminal uses a second key to perform cell handover, wherein the second key is a key corresponding to the source cell.

8. The method according to any one of claims 1-7, characterized in that, The first piece of information is the next hop chain counter (NCC).

9. The method according to any one of claims 1-8, characterized in that, The first information is carried by the switching command.

10. The method according to any one of claims 1-9, characterized in that, The method further includes: If the terminal performs a cell handover and the handover is successful, the terminal discards the first information.

11. The method according to any one of claims 1-10, characterized in that, The method further includes: If the terminal determines that it cannot quickly restore the connection during the RRC connection reconstruction process, the terminal sends a request message to the network-side device, the request message being used to request connection reconstruction.

12. A cell handover method, characterized in that, include: The network-side device sends a handover command to the terminal. The handover command is used to indicate the target cell for handover and carries first information. During the process of the terminal switching to the target cell, the network-side device communicates with the terminal using a second key, which is a key corresponding to the source cell; The first information is used for rapid recovery after the terminal fails to switch over.

13. A cell handover device, characterized in that, include: A receiving module is used to receive first information sent by a network-side device, wherein the first information is used to generate a key. The processing module is used to determine whether to perform cell handover based on the first information, based on the source cell and the target cell for cell handover. The processing module is further configured to determine whether to perform rapid recovery based on the first information during the Radio Resource Control (RRC) connection reconstruction process when the terminal performs cell handover and the handover fails.

14. The apparatus according to claim 13, characterized in that, The processing module is specifically used for at least one of the following: If the terminal performs a cell handover and the handover fails, and the first identifier and the second identifier do not match, then it is determined that a fast recovery will be performed based on the first information during the RRC connection reconstruction process. If the terminal performs a cell handover and the handover fails, and the first identifier matches the second identifier, then it is determined that the first information will not be used for fast recovery during the RRC connection reconstruction process. Wherein, the first identifier is an identifier associated with the source cell, and the second identifier is an identifier associated with the first cell selected by the terminal, the first cell being used for fast recovery.

15. The apparatus according to claim 14, characterized in that, The processing module is specifically used for: If the terminal performs a cell handover and the handover fails, and if the first identifier and the second identifier do not match, then during the RRC connection reconstruction process, the terminal generates a first key based on the first information. The terminal uses the first key for rapid recovery.

16. The apparatus according to claim 14 or 15, characterized in that, If the terminal determines that the first information will not be used for fast recovery during RRC connection reconstruction, the processing module is further configured to: During RRC connection reconstruction, a second key is used for rapid recovery; The second key is the key corresponding to the source cell.

17. The apparatus according to any one of claims 13-16, characterized in that, The processing module is specifically used for at least one of the following: If the first identifier and the third identifier do not match, cell handover is performed based on the first information; If the first identifier matches the third identifier, the first information is not used for cell handover. Wherein, the first identifier is an identifier associated with the source cell, and the third identifier is an identifier associated with the target cell.

18. A cell handover device, characterized in that, include: The sending module is used to send a handover command to the terminal, wherein the handover command is used to indicate the target cell for handover, and the handover command carries first information; During the process of the terminal switching to the target cell, the network-side device communicates with the terminal using a second key, which is a key corresponding to the source cell; The first information is used for rapid recovery after the terminal fails to switch over.

19. A terminal, characterized in that, It includes a processor and a memory, the memory storing programs or instructions that can run on the processor, the programs or instructions being executed by the processor to implement the steps of the cell handover method as described in any one of claims 1 to 12.

20. A network-side device, characterized in that, It includes a processor and a memory, the memory storing programs or instructions that can run on the processor, the programs or instructions being executed by the processor to implement the steps of the cell handover method as described in claim 13.

21. A readable storage medium, characterized in that, The readable storage medium stores a program or instructions that, when executed by a processor, implement the cell handover method as described in any one of claims 1 to 12, or implement the steps of the cell handover method as described in claim 13.

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