Communication method and device and computer readable storage medium

Abstract

A communication method and apparatus, and a computer readable storage medium, the communication method comprising: in response to a radio resource control (RRC) reconfiguration completion signaling sent by a terminal device in a target cell, sending a request message to a first network device, the request message being used for requesting target context information of the terminal device; and obtaining the target context information. By adopting the scheme, the terminal equipment can smoothly execute cell switching and access to the target cell.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication technologies, and in particular to a communication method and device, and a computer-readable storage medium. Background Art

[0002] New Radio (NR) systems introduce continuous handover solutions, such as Layer 1 / L2-Triggered Mobility (LTM) handover. Network equipment configures multiple candidate cells for a terminal device and triggers the terminal device to switch to the target cell via a Media Access Control Element (MAC CE). The terminal device then retains other candidate cells for subsequent handovers.

[0003] With the evolution of communication technology, in subsequent communication protocol versions, candidate cells may belong to different centralized units (CUs) or base stations, and the keys corresponding to different CUs or base stations may be different. After the terminal device performs LTM handover to the serving cell, if the LTM handover fails again in the serving cell, or if a radio link failure occurs, the terminal device performs cell selection. If the terminal device selects a target cell that belongs to a different centralized unit or base station than the serving cell, the terminal device may not be able to access the target cell normally. Summary of the Invention

[0004] The present invention aims to provide a communication method, which enables a terminal device to smoothly perform cell switching and access a target cell.

[0005] In a first aspect, the present invention provides a communication method, comprising: in response to a radio resource control RRC reconfiguration completion signaling sent by a terminal device in a target cell, sending a request message to a first network device, wherein the request message is used to request target context information of the terminal device; and obtaining the target context information.

[0006] The target network device may send a request message to the first network device to request the first network device to send target context information. The target network device parses the RRC reconfiguration completion signaling based on the acquired target context information, thereby enabling the terminal device to switch and access the target cell.

[0007] Optionally, the first network device is different from the target network device to which the target cell belongs. Specifically, the first network device is different from the target network device, and the key corresponding to the first network device (such as the horizontal key KgNB) is different from the key corresponding to the target network device.

[0008] When the target network device is different from the first network device, the request message is sent to the first network device. If the target network device is the same as the first network device, the target network device does not need to send a request message to the first network device.

[0009] Optionally, the first network device includes a first cell, and the first cell is the cell that the terminal device last accessed.

[0010] The target context information of the terminal device is associated with the cell (first cell) that the terminal device last accessed. Thus, the target network device sends a request message to the first network device, and the first network device generates the target context information. Based on the received target context information, the target network device parses the RRC reconfiguration completion signaling sent by the terminal device.

[0011] Optionally, the target context information is derived based on first context information and information of the target cell, where the first context information is context information used by the terminal device in the first cell.

[0012] Optionally, the information of the target cell includes at least one of the following: a physical cell identifier of the target cell, and a downlink frequency of the first target.

[0013] Optionally, the target network device may also obtain first identification information used by the terminal device in the first cell, where the first identification information includes a cell wireless network temporary identification.

[0014] The target network device may determine the first cell based on the first identification information used by the terminal device in the first cell, and then send a request message to the first network device to which the first cell belongs.

[0015] Optionally, the target network device may obtain the first identification information previously sent by the first cell; or, the target network device may also obtain the first information sent by the terminal device, where the first information includes the first identification information.

[0016] Optionally, the target network device may further determine the first cell. The target network device may obtain identification information of the first cell from the RRC reconfiguration completion signaling, thereby determining the first cell. Alternatively, the target network device may also obtain second information sent by the terminal device, where the second information indicates the first cell, and the second information may be sent via layer 2 signaling.

[0017] Optionally, the target network device can also obtain configuration information to learn the network device to which each candidate cell corresponding to the terminal device belongs; or, the configuration information is used to indicate an LTM candidate cell that belongs to the same network device as the first cell; or, the configuration information is used to indicate an LTM candidate cell that belongs to a different network device than the first cell.

[0018] In a second aspect, the present invention also provides another communication method, which can be applied to a terminal device, including: deriving a target key in response to the selected target cell being an LTM candidate cell, and the target cell and the first cell belonging to different network devices; the first cell is the cell most recently accessed by the terminal device; and sending a radio resource control RRC reconfiguration completion signaling to the target cell.

[0019] After determining that the selected target cell is an LTM candidate cell and that the target cell and the first cell belong to different network devices, the terminal device can derive a target key and send an RRC reconfiguration completion signaling to the target cell based on the target key.

[0020] Optionally, after configuring the LTM candidate cells, the terminal device detects a radio link failure or a cell handover failure and performs a cell selection process.

[0021] Optionally, if the target cell and the first cell belong to the same network device, the terminal device uses a first key to send an RRC reconfiguration completion signaling to the target cell; the first key is the key used by the terminal device to access the first cell.

[0022] If the target cell and the first cell belong to the same network device, since the same network device uses the same key, the target cell can directly use the first key to send the RRC reconfiguration completion signaling to the target cell.

[0023] Optionally, the terminal device obtains the network device to which the configured LTM candidate cell belongs; or obtains the LTM candidate cell that belongs to the same network device as the first cell; or obtains the LTM candidate cell that belongs to a different network device than the first cell.

[0024] In a third aspect, the present invention also provides a communication device, including: a sending unit, used to send a request message to a first network device in response to a wireless resource control reconfiguration completion signaling sent by a terminal device in a target cell, wherein the request message is used to request target context information of the terminal device; and an acquiring unit, used to acquire the target context information.

[0025] In a fourth aspect, the present invention also provides another communication device, which is applied to a terminal device, including: a processing unit, used to derive a target key in response to the selected target cell being an LTM candidate cell, and the target cell and the first cell belong to different network devices; the first cell is the cell that the terminal device last accessed; and a sending unit, used to send a radio resource control RRC reconfiguration completion signaling to the target cell.

[0026] In a fifth aspect, the present invention also provides a computer-readable storage medium, which is a non-volatile storage medium or a non-transient storage medium, on which a computer program is stored, and when the computer program is run by a processor, the steps of any of the above-mentioned communication methods are executed.

[0027] In a sixth aspect, the present invention also provides another communication device, comprising a memory and a processor, wherein the memory stores a computer program that can be run on the processor, and the processor executes the steps of any one of the above-mentioned communication methods when running the computer program. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a flow chart of LTM condition switching;

[0029] Figure 2 is a flow chart of a communication method in an embodiment of the present invention;

[0030] Figure 3 This is a schematic diagram of mapping between cells and network devices in an embodiment of the present invention;

[0031] Figure 4 is a flow chart of another communication method in an embodiment of the present invention;

[0032] Figure 5 is a schematic structural diagram of a communication device in an embodiment of the present invention;

[0033] Figure 6 It is a structural diagram of another communication device in an embodiment of the present invention. DETAILED DESCRIPTION

[0034] In R18, all candidate cells use the same key during LTM handover. In R19, different candidate cells may belong to different CUs and require different keys.

[0035] For example, source cell 0, candidate cell 1, candidate cell 2, and candidate cell 3 all belong to centralized unit CU1 and use key 1. Candidate cells 4 and 5 belong to centralized unit CU2 and need to use a key different from key 1. Candidate cells 6 and 7 belong to centralized unit CU3 and need to use a key different from both key 1 and key 2.

[0036] The terminal device performs LTM switching, switching from the source cell cell 0 to the candidate cell cell 1. Since cell 0 and cell 1 belong to the same centralized unit, the key has not changed. In the serving cell (i.e., cell 1), the terminal device can perform LTM switching again. If the terminal device fails to perform LTM switching (i.e., fails to successfully access the target cell for switching), or a radio link failure occurs, the terminal device can perform cell selection. Assume that the terminal device selects cell 4 as the target cell. The terminal device uses a new key to send an RRC reconfiguration completion signaling to cell 4. The new key is derived based on key 1, the physical cell identifier (PCI) of cell 4, and the downlink frequency (DL Frequency) of cell 4 (the specific derivation algorithm can be based on the algorithm provided in the existing protocol). The specific meaning of the above-mentioned physical cell identifier can refer to the corresponding description in the existing protocol TS33.501 6.9.2.

[0037] However, cell 4 cannot determine whether the cell (i.e., cell 1) that the terminal device accessed before performing this cell selection belongs to CU1 or CU3. Therefore, cell 4 cannot obtain the key used by the terminal device (because the actual switching path is unpredictable), and thus cannot parse the RRC reconfiguration completion signaling sent by the terminal device, resulting in the terminal device being unable to switch to the target cell (cell 4) normally.

[0038] In an embodiment of the present invention, the target network device may send a request message to the first network device to request the first network device to send target context information. The target network device parses the RRC reconfiguration completion signaling based on the obtained target context information, thereby enabling the terminal device to switch and access the target cell.

[0039] In the embodiment of the present invention, the context information may refer to a key used by the terminal device, or may include a key used by the terminal device, a wireless configuration parameter used by the terminal device, etc. Correspondingly, the target context information may refer to a target key used by the terminal device in a target cell, or the target context information may refer to a target key of the terminal device and other wireless configuration parameters (such as quality of service QoS, etc.).

[0040] In order to make the above-mentioned objects, features and beneficial effects of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0041] The terminal device described in the embodiments of the present application is a device with wireless communication capabilities, and may also be referred to as a terminal, mobile station (MS), mobile terminal (MT), access terminal equipment, vehicle-mounted terminal equipment, industrial control terminal equipment, user equipment (UE), UE unit, UE station, mobile station, remote station, remote terminal equipment, mobile device, wireless communication device, UE agent, or UE device. The UE can be fixed or mobile. It should be noted that the UE can support at least one wireless communication technology, such as LTE, NR, etc. Exemplarily, the UE may be a mobile phone, a tablet computer, a desktop computer, a laptop computer, an all-in-one computer, an in-vehicle terminal, a virtual reality (VR) UE, an augmented reality (AR) UE, a wireless terminal in industrial control, a wireless terminal in self-driving, a wireless terminal in remote medical surgery, a wireless terminal in a smart grid, a wireless terminal in transportation safety, a wireless terminal in a smart city, a wireless terminal in a smart home, a cellular phone, a cordless phone, a session initiation protocol (SIP) phone, a wireless local loop (WLL) station, a personal digital assistant (PDA), a handheld device with wireless communication capabilities, a computing device or other processing device connected to a wireless modem, a wearable device, a UE in a future mobile communication network, or a UE in a future evolved public mobile land network (PLMN), etc. In some embodiments of the present application, the UE may also be a device with transceiver functions, such as a chip system, wherein the chip system may include a chip and may also include other discrete devices.

[0042] In the embodiment of the present application, a network device is a device that provides wireless communication functions for a terminal device, and may also be referred to as a radio access network (RAN) device, an access network element, an access network device, etc. The network device may support at least one wireless communication technology, such as LTE, NR, etc. For example, the network device includes, but is not limited to: a next-generation base station (gNB) in 5G, an evolved node B (eNB), a radio network controller (RNC), a node B (NB), a base station controller (BSC), a base transceiver station (BTS), a home base station (e.g., home evolved node B, or home node B, HNB), a baseband unit (BBU), a transmitting and receiving point (TRP), a transmitting point (TP), a mobile switching center, etc. The network device may also be a wireless controller, a centralized unit (CU), and / or a distributed unit (DU) in a cloud radio access network (CRAN) scenario, or the network device may be a relay station, an access point, an on-board device, a terminal device, a wearable device, a network device in future mobile communications, or a network device in a future evolved PLMN. In some embodiments, the network device may also be a device that provides wireless communication functions for a terminal device, such as a chip system. For example, the chip system may include a chip and may also include other discrete devices.

[0043] In some embodiments, the network device may also communicate with an Internet Protocol (IP) network, such as the Internet, a private IP network, or other data networks.

[0044] Reference Figure 1 , a flow chart of LTM conditional switching is given. It can be understood that the following steps 101 to 108 only generally describe the process of LTM conditional switching.

[0045] Step 101: The terminal device sends a measurement report to the network device.

[0046] The terminal device accesses the source cell. When the terminal device is in the RRC connected state, the network device can configure measurement configuration information for the terminal device. The terminal device can perform measurement operations based on the measurement configuration information. The terminal device detects a cell or neighboring cell that meets the reporting conditions and reports a measurement report.

[0047] Step 102: The network device configures candidate cells for the terminal device.

[0048] In a specific implementation, the network device can configure one or more LTM candidate cells for the terminal device through RRC reconfiguration signaling, as well as the switching conditions (or switching execution conditions) corresponding to one or more LTM candidate cells, such as the signal quality threshold of the LTM candidate cell is higher than the preset threshold.

[0049] In addition, the network device can also configure the uplink resources used by the terminal device to report layer 1 measurement results through RRC reconfiguration signaling.

[0050] For example, the network device configures candidate cells 1 to 7 for the terminal device, candidate cells 1 to 3 belong to CU1, candidate cells 4 to 5 belong to CU2, and candidate cells 6 to 7 belong to CU3.

[0051] In a specific implementation, the network device corresponding to the source cell can clearly indicate to the terminal device the CU or base station to which different candidate cells belong. The network device corresponding to the source cell can also configure information so that the terminal device can know the candidate cells in the same CU or base station, and then infer the candidate cells belonging to different CUs or base stations.

[0052] Step 103: The terminal device sends an RRC reconfiguration completion signaling.

[0053] In a specific implementation, the terminal device receives the RRC reconfiguration signaling and feeds back an RRC reconfiguration complete signaling to the network device.

[0054] Step 104: The terminal device performs uplink and downlink synchronization with the candidate cell.

[0055] In a specific implementation, the terminal device can achieve downlink and uplink synchronization with the candidate cell based on RRC reconfiguration signaling, as well as subsequent Layer 2 signaling and Layer 1 signaling. This step is optional. If uplink synchronization with the candidate cell is required, the serving cell triggers the terminal device to send a random access preamble to the candidate cell via Layer 1 signaling. The network side obtains the uplink advance TA based on the preamble sent by the terminal device.

[0056] Step 105: The terminal device reports the layer 1 measurement result.

[0057] In a specific implementation, the terminal device may report the layer 1 measurement result of the serving cell and the layer 1 measurement result of at least one candidate cell to the network device.

[0058] Step 106: The network device sends a cell switching command to the terminal device.

[0059] In a specific implementation, the network device determines that the terminal device performs cell switching based on the layer 1 measurement result of the serving cell and the layer 1 measurement result of at least one candidate cell. The network device sends a cell switch command to the terminal device via MAC CE signaling. Step 106 is optional.

[0060] If the terminal device finds that a candidate cell meets the switching execution conditions, the terminal device does not need to perform switching based on the cell switching command sent by the network device, but can directly access the candidate cell that meets the switching execution conditions.

[0061] Step 107: The terminal device performs a random access process.

[0062] In a specific implementation, if the terminal device does not receive the timing advance (TA) of the target cell, the terminal device needs to perform a random access process in the target cell.

[0063] Step 108: The terminal device sends an RRC reconfiguration completion signaling to the target cell.

[0064] The communication method provided in the embodiment of the present invention is described in detail below. Figure 2 , a flowchart of a communication method according to an embodiment of the present invention is given.

[0065] In an embodiment of the present invention, the communication method provided in the following steps 201 to 202 can be executed by a chip with data processing capabilities in the target network device, or by a chip module with data processing capabilities in the target network device, or by the target network device. In the following embodiment, the communication method is executed by the target network device as an example. The above-mentioned target network device may refer to a CU or base station to which the target cell belongs.

[0066] In specific applications, it can be seen that in the 5G network, the baseband processing unit (Base Band Unit, BBU) is split into a distributed unit (DU) and a centralized unit (CU). Among them, the CU is mainly responsible for non-real-time wireless high-level protocol stack functions, and also supports the sinking of some core network functions and the deployment of edge application services; the DU mainly processes physical layer functions and layer 2 functions with real-time requirements. In some embodiments, the media access layer (MAC) and the radio link control (Radio Link Control, RLC) layer can be processed in the DU, and the packet data convergence protocol (Packet Data Convergence Protocol, PDCP) and RRC layer can be processed in the CU. For a CU, one or more cells can be served.

[0067] Step 201: In response to the RRC reconfiguration completion signaling sent by the terminal device in the target cell, a request message is sent to the first network device.

[0068] In a specific implementation, before the target network device executes step 201, the terminal device first performs cell switching and accesses the target cell.

[0069] Step 202: Obtain target context information.

[0070] In the embodiment of the present invention, after the terminal device accesses the source cell, the network device corresponding to the source cell may configure one or more candidate cells for the terminal device. In the following embodiments, unless otherwise stated, the candidate cells may all be LTM candidate cells.

[0071] In some optional embodiments, the network equipment corresponding to the source cell can configure handover execution conditions for each candidate cell. If handover execution conditions are not configured, the terminal device accesses the target cell after receiving a cell handover command from the network equipment corresponding to the source cell. If handover execution conditions are configured, the terminal device can select one of the candidate cells that meet the handover execution conditions for access upon discovering that a candidate cell meets the handover execution conditions. Even if handover execution conditions are configured, once the network equipment sends a cell handover command, the terminal device must implement the cell handover according to the cell handover command.

[0072] Because there are scenarios where a terminal device performs continuous LTM handovers, in the following embodiments, the candidate cell selected by the terminal device during the current cell selection process is used as the target cell, and the cell most recently accessed by the terminal device before handing over to the target cell is used as the first cell. In some embodiments, the first cell may also be referred to as the previous serving cell of the terminal device.

[0073] In a specific implementation, after the terminal device accesses the first cell, it can conduct business, evaluate candidate cells, and report measurement results. After a period of time, the terminal device detects that the wireless link fails, or the first cell triggers the terminal device to perform a new switch but the switch fails (i.e., it does not successfully access the cell to be switched, and the first cell is still the cell that the terminal device last accessed), or the terminal device performs a conditional switch but the switch fails (i.e., it does not successfully access the cell to be switched, and the first cell is still the cell that the terminal device last accessed). The terminal device can perform cell selection. If the selected cell is a candidate cell, the terminal device performs a switch and switches to the selected candidate cell, which becomes the target cell.

[0074] The terminal device can access the target cell using the cell configuration information corresponding to the target cell. The terminal device can update the context (UE CONTEXT) information. Specifically, the terminal device can generate target context information based on the context information used in the first cell (hereinafter referred to as the first context information) and the information of the target cell. When switching to the target cell, the terminal device can use the target context information to process the RRC reconfiguration completion signaling.

[0075] In a specific implementation, the context information of the terminal device may include a key (KgNB). The terminal device can perform encryption and integrity protection on the RRC reconfiguration completion signaling based on the key. When the terminal device switches to the first cell, the RRC reconfiguration completion signaling is processed using the first key. Accordingly, when the terminal device switches to the target cell, the RRC reconfiguration completion signaling is processed using the target key. Here, the first cell and the target cell belong to different network devices, that is, they belong to different CUs or base stations.

[0076] In some embodiments, when a terminal device switches from a first cell to a target cell, the terminal device may use the first key used in the first cell, the PCI corresponding to the target cell, and the downlink frequency of the target cell to generate a target key (KgNB*) used in the target cell, and use the target key to encrypt and perform integrity protection on the RRC reconfiguration completion signaling. Specifically, the process of deriving the encryption key and the integrity protection key from the target key may adopt an existing mechanism, and the encryption and integrity protection of the RRC reconfiguration completion signaling may also adopt an existing mechanism.

[0077] In an embodiment of the present invention, the target network device may receive an RRC reconfiguration completion signaling sent by the terminal device in the target cell. Since the RRC reconfiguration completion signaling is encrypted and integrity protected using the target key, and the target network device has not yet learned the target key, the target network device may send a request message to the first network device to obtain target context information, where the target context information includes the target key.

[0078] In a specific implementation, the first network device is the network device to which the first cell belongs, and the first network device may be a centralized unit, a base station, or other device that provides services to the terminal device. Accordingly, the target network device is the network device to which the target cell belongs.

[0079] In this embodiment of the present invention, if the target network device is different from the first network device, since the key used by the first network device is different from the key used by the target network device, the target network device sends a request message to the first network device to obtain target context information (target key).

[0080] For example, the first cell is cell 1, the target cell is cell 4, the first network device is CU1, and the target network device is CU2. CU2 sends a request message to CU1 to obtain the target key. Upon receiving the request message, CU1 determines the key KgNB* used by the terminal device in cell 4 based on the key KgNB used by the terminal device in cell 1, the PCI of cell 4, and the downlink frequency of cell 4. It then sends the key KgNB* to CU2.

[0081] If the target network device is the same as the first network device, the target network device may not need to send a request message to the first network device because the key used by the first network device is the same as the key used by the target network device.

[0082] For example, the first cell is cell 1, the target cell is cell 2, the first network device is CU1, and the target network device is also CU1. In this scenario, CU1 can directly parse the RRC reconfiguration completion signaling sent by the terminal device.

[0083] In an embodiment of the present invention, the target network device may obtain the first identification information used by the terminal device in the first cell. In some embodiments, the first identification information may be a Cell-Radio Network Temporary Identifier (C-RNTI) allocated by the first cell to the terminal device. In other embodiments, the first identification information may be other information configured by the core network device for the terminal device that can identify the terminal device.

[0084] In a specific implementation, after a terminal device accesses a first cell, the first network device may send the first identification information to the network devices corresponding to all candidate cells. Alternatively, when initially configuring candidate cells, the network device corresponding to the source cell may send the first identification information allocated to the terminal device by different candidate cells to other network devices. In this way, the target network device can determine the first identification information used by the terminal device in the first cell.

[0085] Alternatively, when the terminal device switches to the target cell (referring to the random access process), the first information is sent. The first information may include the first identification information, or include the identification of the most recently accessed cell (i.e., the identification information of the first cell) and the first identification information. Upon receiving the first information, the target network device can determine the first identification information used by the terminal device in the first cell.

[0086] Thus, the target network device can determine the first cell and the first network device based on the first identification information of the terminal device, or based on the identification of the most recently accessed cell (ie, the identification information of the first cell) and the first identification information.

[0087] For example, after a terminal device accesses cell 0, the network device CU0 corresponding to cell 0 configures candidate cells 1 through 7 for the terminal device. Cells 1 through 3 belong to CU1, cells 4 through 5 belong to CU2, and cells 6 through 7 belong to CU3. CU0 sends the C-RNTI used by the terminal device in cells 1 through 7 to CU1, CU2, and CU3.

[0088] The first cell is cell 1, and the target cell is cell 4. When the target network device is CU2, it can be determined that the cell that the terminal device last accessed is cell 1 based on the first identification information of the terminal device.

[0089] In the embodiment of the present invention, the target network device may also determine the first cell, and then determine the first network device.

[0090] In a specific implementation, the terminal device may carry the identification information of the first cell in the RRC reconfiguration completion signaling sent to the target cell; or carry the identification information of the first cell and the first identification information of the terminal device in the RRC reconfiguration completion signaling. The target network device receives the RRC reconfiguration completion signaling and obtains the identification information of the first cell therefrom.

[0091] Alternatively, the terminal device may send second information to the target cell, where the second information indicates the identification information of the first cell; or the second information may indicate the identification information of the first cell and the first identification information of the terminal device. The terminal device may send the second information via layer 2 signaling (such as MAC CE, etc.). The target network device may determine the first cell based on the received second information.

[0092] In an embodiment of the present invention, the target network device may further obtain configuration information, and the configuration information may indicate the network device to which each candidate cell corresponding to the terminal device belongs; or, the configuration information may be used to indicate a candidate cell belonging to the same network device as the first cell (or a candidate cell belonging to the same network device as the target cell); or, the configuration information may be used to indicate a candidate cell belonging to a different network device than the first cell (or a candidate cell belonging to a different network device than the target cell).

[0093] In a specific implementation, when a terminal device accesses a source cell, the network device corresponding to the source cell may configure candidate cells for the terminal device. Different candidate cells may belong to different network devices. The network device corresponding to the source cell may send configuration information to the network devices to which each candidate cell belongs, so that each network device can learn about the network devices to which other candidate cells belong, or learn about the candidate cells configured for the terminal device by other network devices.

[0094] For example, after a terminal device accesses source cell 0, network device CU0 corresponding to cell 0 configures candidate cells 1 through 7 for the terminal device. Cells 1 through 3 belong to CU1, cells 4 through 5 belong to CU2, and cells 6 through 7 belong to CU3. CU0 sends configuration information to CU1, CU2, and CU3, indicating that cells 1 through 3 belong to CU1, cells 4 through 5 belong to CU2, and cells 6 through 7 belong to CU3.

[0095] Alternatively, CU0 may indicate to CU1 that CU2 and CU3 are candidate cells configured for the terminal device, indicate to CU2 that CU1 and CU3 are candidate cells configured for the terminal device, and indicate to CU3 that CU1 and CU2 are candidate cells configured for the terminal device.

[0096] The communication method provided in the above embodiment of the present invention is described below through specific examples.

[0097] Reference Figure 3 , a schematic diagram of mapping between cells and network devices in an embodiment of the present invention is given.

[0098] The terminal device initially resides in the source cell, cell 0. The network device to which source cell 0 belongs configures candidate cells for the terminal device. The candidate cells include cells 1 to 7. Cell 0 and cells 1 to 3 belong to CU1, cells 4 to 5 belong to CU2, and cells 6 to 7 belong to CU3.

[0099] The terminal device performs an LTM handover from cell 0 to cell 1 (the first cell). Since cell 1 and cell 0 belong to the same CU, no key update occurs. The terminal device can directly use the key used in cell 0 to encrypt and integrity protect the RRC reconfiguration complete signaling. The network device corresponding to cell 1 can directly process the received RRC reconfiguration complete signaling.

[0100] The terminal device performs the corresponding service processing in cell 1, continues to evaluate other candidate cells (cells 2 to 7, or cell 0, cell 2 to 7), and reports the measurement results. After a period of time, the terminal device detects a radio link failure; either cell 1 triggers the terminal device to perform a new (LTM) handover, or the terminal device performs a conditional handover, but the handover fails, and the terminal device performs cell selection.

[0101] In the first scenario, the terminal device selects a candidate cell that belongs to the same CU as cell 1, such as cell 2. The terminal device uses the cell configuration information corresponding to cell 2 to access cell 2. Because cell 2 and cell 1 belong to the same CU, no key update is required. Therefore, when the terminal device accesses cell 2, it sends an RRC reconfiguration complete signaling to cell 2. Cell 2 parses the RRC reconfiguration complete signaling based on its existing key, and the terminal device accesses cell 2.

[0102] The second scenario is that the terminal device selects a candidate cell that belongs to a different CU than cell 1, such as cell 4. The terminal device generates a key for use in cell 4 based on the key used in cell 1, the PCI corresponding to cell 4, and the downlink frequency corresponding to cell 4. (The above cell 1 is an example of the first cell, and the key used in cell 1 is an example of the above first key; the above cell 4 is an example of the target cell, and the key used in cell 4 is an example of the above target key).

[0103] During the random access process (contention-based random access) of accessing cell 4, the terminal device reports the C-RNTI to cell 4 (the C-RNTI allocated by cell 4 to the terminal device, which belongs to the candidate cell configuration information), and cell 4 identifies the terminal device based on the C-RNTI of the terminal device.

[0104] For the second scenario, there are two sub-scenarios:

[0105] In sub-scenario 1, CU2 clearly learns that the first network device is CU1.

[0106] In this scenario, CU2 sends a request message to CU1. After receiving the request message, CU1 generates a target key, KgNB*, for use in cell 4 based on the terminal device's first key, KgNB, used in cell 1, combined with the PCI and downlink frequency corresponding to cell 4. It then sends the target key, KgNB*, to CU2. Based on the received target key, KgNB*, CU2 parses the RRC reconfiguration completion signaling sent by the terminal device. Upon successful parsing, the terminal device successfully connects to cell 4.

[0107] For sub-scenario 1 above, the terminal device carries the identification information of cell 1 in the RRC reconfiguration complete signaling sent to cell 4. Alternatively, the RRC reconfiguration complete signaling carries the identification information of cell 1 and the C-RNTI allocated by cell 1 to the terminal device. Based on the identification information of cell 1, CU2 determines that the cell the terminal device last accessed is cell 1 and the CU to which cell 1 belongs is CU1.

[0108] Alternatively, the terminal device sends second information to cell 4, where the second information indicates the first cell identifier, or the second information indicates the identifier information of cell 1 and the C-RNTI allocated to the terminal device by cell 1. Based on the second information, CU2 determines that the cell most recently accessed by the terminal device is cell 1 and that the CU to which cell 1 belongs is CU1. The terminal device can send the second information via layer 2 signaling. This is because cell 4 cannot accurately parse the RRC reconfiguration completion signaling at this time, and therefore the terminal device needs to indicate the second information in layer 2 so that cell 4 can obtain the second information without decryption.

[0109] In sub-scenario 2, CU2 can learn that the first network device is CU1 or CU3.

[0110] After the terminal device accesses cell 0, the network device corresponding to cell 0 (ie, CU1) sends configuration information to all CUs configured with candidate cells. The configuration information indicates the CU corresponding to the candidate cell of the terminal device. Thus, CU2 can know that the first network device is CU1 or CU3.

[0111] CU2 sends request messages to CU1 and CU3 respectively. In the request information, the identification information of the cell that the terminal device recently accessed (i.e., the identification of cell 1) may be indicated, or the identification information of the cell that the terminal device recently accessed (i.e., the identification of cell 1) and the C-RNTI in the cell (i.e., the C-RNTI allocated by cell 1 to the terminal device) may be indicated. CU1 receives the request message sent by CU2, and based on the first key KgNB used by the terminal device in cell 1, combined with the PCI and downlink frequency corresponding to cell 4, generates the target key KgNB* used in cell 4, and sends the target key KgNB* to CU2. Based on the received target key KgNB*, CU2 parses the RRC reconfiguration completion signaling sent by the terminal device. After successful parsing, the terminal device accesses cell 4.

[0112] CU3 receives the request message sent by CU2 and determines that cell 1 does not belong to CU3. Therefore, it can ignore the request message or feedback empty information to CU2.

[0113] In summary, in an embodiment of the present invention, the target network device may send a request message to the first network device to request the first network device to send target context information. The target network device parses the RRC reconfiguration completion signaling based on the obtained target context information, thereby enabling the terminal device to switch and access the target cell.

[0114] In an embodiment of the present invention, when a terminal device detects that a candidate cell belonging to a different CU has been selected during cell selection, i.e., a candidate cell belonging to a different CU than the cell most recently accessed, the terminal device may also directly trigger an RRC reestablishment process. The specific implementation of the RRC reestablishment process may refer to existing protocols.

[0115] For example, the first cell is cell 1, the target cell is cell 4, the first network device is CU1, and the target network device is CU2. The terminal device determines that the target network device is different from the first network device, and the terminal device initiates an RRC reestablishment process in cell 4.

[0116] The present invention also provides another communication method, referring to Figure 4 , the following is a detailed description through specific steps.

[0117] In an embodiment of the present invention, the communication method provided in steps 401 to 402 below can be executed by a chip with data processing capabilities in a terminal device, or by a chip module with data processing capabilities in the terminal device, or by the terminal device. In the following embodiment, the communication method is described as an example of a terminal device executing the communication method.

[0118] Step 401: In response to the selected target cell being an LTM candidate cell, and the target cell and the first cell belong to different network devices, derive a target key.

[0119] Step 402: Send RRC reconfiguration completion signaling to the target cell.

[0120] In a specific implementation, the terminal device can obtain the network devices to which all LTM candidate cells belong; or, the terminal device can obtain the LTM candidate cells that belong to the same network device as the first cell; or, the terminal device can obtain the LTM candidate cells that belong to different network devices than the first cell.

[0121] In this way, the terminal device can learn the correspondence between the LTM candidate cells and the network devices.

[0122] In an embodiment of the present invention, the candidate cell selected by the terminal device in the current cell selection process is used as the target cell, and the cell that the terminal device most recently accessed before switching to the target cell (the cell successfully accessed) is used as the first cell.

[0123] In a specific implementation, after a terminal device accesses the first cell, it can conduct services, evaluate candidate cells, and report measurement results. After a period of time, if the terminal device detects a radio link failure, or if the first cell triggers the terminal device to perform a new handover but the handover fails, or if the terminal device performs a conditional handover but the handover fails, the terminal device can perform cell selection. If the selected cell is a candidate cell, it selects the candidate cell as the target cell and performs handover to the target cell.

[0124] The terminal device can access the target cell using the cell configuration information corresponding to the target cell. The terminal device can update the context (UE CONTEXT) information. Specifically, the terminal device can generate target context information based on the context information used in the first cell (hereinafter referred to as the first context information, specifically the key) and the information of the target cell. When switching to the target cell, the terminal device can use the target context information to process the RRC reconfiguration completion signaling.

[0125] In a specific implementation, the context information of the terminal device may include a key (KgNB). The terminal device may perform encryption and integrity protection on the RRC reconfiguration completion signaling based on the key. When the terminal device switches to the first cell, the first key is used to process the RRC reconfiguration completion signaling. Accordingly, when the terminal device switches to the target cell, the target key is used to process the RRC reconfiguration completion signaling.

[0126] In some embodiments, when a terminal device switches from a first cell to a target cell, the terminal device may use the first key used in the first cell, the PCI corresponding to the target cell, and the downlink frequency of the target cell to generate a target key used in the target cell, and use the target key to encrypt and perform integrity protection on the RRC reconfiguration completion signaling.

[0127] It should be noted that the specific description of the above steps 401 to 402 can refer to the description of the terminal device involved in the above steps 201 to 202, and no detailed description is given here.

[0128] Reference Figure 5 , a communication device 50 in an embodiment of the present invention is provided, comprising: a sending unit 501 and an acquiring unit 502, wherein:

[0129] A sending unit 501 is configured to send a request message to a first network device in response to a radio resource control reconfiguration completion signaling sent by a terminal device in a target cell, wherein the request message is used to request target context information of the terminal device;

[0130] The acquiring unit 502 is configured to acquire the target context information.

[0131] In a specific implementation, the specific execution process of the sending unit 501 and the obtaining unit 502 may correspond to steps 201 to 202, which will not be described in detail here.

[0132] In a specific implementation, the above-mentioned communication device 50 may correspond to a chip with a data processing function in a network device, or correspond to a chip module with a data processing function in a network device, or correspond to a network device.

[0133] Reference Figure 6 , a communication device 60 in an embodiment of the present invention is provided, comprising: a processing unit 601 and a sending unit 602, wherein:

[0134] Processing unit 601 is configured to derive a target key in response to a selected target cell being an LTM candidate cell, and the target cell and a first cell belonging to different network devices; the first cell being a cell most recently accessed by the terminal device;

[0135] The sending unit 602 is configured to send an RRC reconfiguration completion signaling to the target cell.

[0136] In a specific implementation, the specific execution process of the above-mentioned processing unit 601 and the sending unit 602 can correspond to step 401 to step 402, which will not be repeated here.

[0137] In a specific implementation, the above-mentioned communication device 60 may correspond to a chip with a data processing function in a terminal device, or correspond to a chip module with a data processing function in a terminal device, or correspond to a terminal device.

[0138] In specific implementations, the modules / units included in the various devices and products described in the above embodiments may be software modules / units or hardware modules / units, or may be partially software modules / units and partially hardware modules / units.

[0139] For example, for each device or product applied to or integrated into a chip, each module / unit contained therein may be implemented in the form of hardware such as circuits, or at least some of the modules / units may be implemented in the form of software programs, which run on a processor integrated inside the chip, and the remaining (if any) modules / units may be implemented in the form of hardware such as circuits; for each device or product applied to or integrated into a chip module, each module / unit contained therein may be implemented in the form of hardware such as circuits, and different modules / units may be located in the same component (such as a chip, circuit module, etc.) or different components of the chip module, or at least some of the modules / units may be implemented in the form of software programs. The element can be implemented in the form of a software program, which runs on the processor integrated inside the chip module, and the remaining (if any) modules / units can be implemented in the form of hardware such as circuits; for various devices and products applied to or integrated in the terminal, the various modules / units contained therein can be implemented in the form of hardware such as circuits, and different modules / units can be located in the same component (for example, chip, circuit module, etc.) or different components in the terminal, or, at least some modules / units can be implemented in the form of a software program, which runs on the processor integrated inside the terminal, and the remaining (if any) modules / units can be implemented in the form of hardware such as circuits.

[0140] An embodiment of the present invention also provides a computer-readable storage medium, which is a non-volatile storage medium or a non-transient storage medium, on which a computer program is stored. When the computer program is run by a processor, the steps of the communication method provided in any of the above embodiments are executed.

[0141] An embodiment of the present invention further provides another communication device, comprising a memory and a processor, wherein the memory stores a computer program that can be run on the processor, and when the processor runs the computer program, the steps of the communication method provided in any of the above embodiments are executed.

[0142] Those skilled in the art will understand that all or part of the steps in the various methods of the above embodiments can be completed by instructing the relevant hardware through a program, and the program can be stored in a computer-readable storage medium, which may include: ROM, RAM, disk or CD, etc.

[0143] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the scope defined by the claims.

Claims

1. A communication method, characterized in that: include: In response to the radio resource control (RRC) reconfiguration completion signaling sent by the terminal device in the target cell, sending a request message to the first network device, where the request message is used to request target context information of the terminal device; Acquire the target context information.

2. The communication method according to claim 1, wherein: The first network device is different from the target network device to which the target cell belongs.

3. The communication method according to claim 2, wherein: The first network device includes a first cell, and the first cell is the cell that the terminal device accessed most recently.

4. The communication method according to claim 3, wherein: The target context information is derived based on first context information and information of the target cell, where the first context information is context information used by the terminal device in the first cell.

5. The communication method according to claim 4, wherein: The information of the target cell includes at least one of the following: a physical cell identifier of the target cell, and a downlink frequency of the target cell.

6. The communication method according to claim 3, wherein: Also includes: Obtain first identification information used by the terminal device in the first cell, where the first identification information includes a cell wireless network temporary identification.

7. The communication method according to claim 6, wherein: The acquiring first identification information used by the terminal device in the first cell includes: acquiring the first identification information previously sent by the first cell; or, Acquire first information sent by the terminal device, where the first information includes the first identification information.

8. The communication method according to claim 3, wherein: Also includes: Determine the first cell.

9. The communication method according to claim 8, wherein: The determining the first cell includes: Obtain identification information of the first cell from the RRC reconfiguration completion signaling; or obtain second information sent by the terminal device, where the second information indicates the first cell and the second information is sent via layer 2 signaling.

10. The communication method according to claim 3, wherein: Also includes: Acquire configuration information, where the configuration information is used to indicate a network device to which each candidate cell corresponding to the terminal device belongs; or, The configuration information is used to indicate an LTM candidate cell belonging to the same network device as the first cell; or, The configuration information is used to indicate an LTM candidate cell that belongs to a network device different from the first cell.

11. The communication method according to any one of claims 1 to 10, wherein: Also includes: Based on the target context information, the RRC reconfiguration completion signaling is verified.

12. A communication method, characterized in that: Applied in terminal equipment, including: In response to the selected target cell being an LTM candidate cell, and the target cell and the first cell belonging to different network devices, deriving a target key; the first cell being the cell most recently accessed by the terminal device; Sending a radio resource control (RRC) reconfiguration completion signaling to the target cell.

13. The communication method according to claim 12, wherein: Also includes: After the LTM candidate cells are configured, if a radio link failure or cell handover failure is detected, the cell selection process is performed.

14. The communication method according to claim 12, wherein: Also includes: If the target cell and the first cell belong to the same network device, sending an RRC reconfiguration completion signaling to the target cell using the first key; The first key is a key used by the terminal device to access the first cell.

15. The communication method according to claim 12, wherein: Also includes: Get the network device to which the configured LTM candidate cell belongs; or, Acquire an LTM candidate cell belonging to the same network device as the first cell; Alternatively, an LTM candidate cell belonging to a network device different from the first cell is obtained.

16. A communication device, characterized in that: include: a sending unit, configured to send a request message to the first network device in response to the radio resource control reconfiguration completion signaling sent by the terminal device in the target cell, wherein the request message is used to request target context information of the terminal device; An acquiring unit is configured to acquire the target context information.

17. A communication device, characterized in that: Applied in terminal equipment, including: a processing unit, configured to derive a target key in response to the selected target cell being an LTM candidate cell, and the target cell and a first cell belonging to different network devices; the first cell being a cell most recently accessed by the terminal device; The sending unit is used to send a radio resource control RRC reconfiguration completion signaling to the target cell.

18. A computer-readable storage medium, wherein the computer-readable storage medium is a non-volatile storage medium or a non-transient storage medium, and a computer program is stored thereon, wherein: When the computer program is executed by a processor, the steps of the communication method according to any one of claims 1 to 11 are executed; or, when the computer program is executed by a processor, the steps of the communication method according to any one of claims 12 to 15 are executed.

19. A communication device comprising a memory and a processor, wherein the memory stores a computer program that can be run on the processor, wherein: When the processor runs the computer program, the processor executes the steps of the communication method according to any one of claims 1 to 11; or, when the processor runs the computer program, the processor executes the steps of the communication method according to any one of claims 12 to 15.

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