Communication method, apparatus and system

Abstract

The present application relates to the technical field of communications, and discloses a communication method, apparatus and system. The method comprises: a terminal device receiving a first message from a first access network device, wherein the first message is used for instructing the terminal device to enter an inactive state; and sending a second message to a second access network device, wherein the second message is used for requesting resumption of an RRC connection of the terminal device, the second message comprises first identification information, the first identification information comprises an identifier of the terminal device and an identifier of a core network device, and the first identification information is used for acquiring context of the terminal device on the basis of the core network device. In this way, the context of the terminal device can be acquired on the basis of the core network device, so that when the first access network device and the second access network device cannot communicate with each other, the second access network device can also acquire the context of the terminal device.

Description

A communication method, apparatus and system

[0001] Cross-reference to related applications

[0002] This application claims priority to Chinese Patent Application No. 202510191930.8, filed on February 19, 2025, entitled "A Communication Method, Apparatus and System", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of communication technology, and in particular to a communication method, apparatus and system. Background Technology

[0004] The state of a terminal device can include Radio Resource Control (RRC) connected state, RRC idle state, and RRC inactive state. The purpose of the inactive state is to allow the terminal device to quickly return to the RRC connected state without having to reconnect.

[0005] For example, after a terminal device enters the connected state in a cell connected to the first access network device, the first access network device instructs the terminal device to switch from the connected state to the inactive state. The inactive terminal device disconnects its RRC connection from the first access network device, but the first access network device still stores the terminal device's context. If the inactive terminal device moves into the coverage area of ​​the second access network device and initiates an RRC recovery request to the second access network device, the second access network device needs to obtain the terminal device's context from the first access network device to restore the terminal device's RRC connection.

[0006] However, how the second access network device can obtain the context of the terminal device from the first access network device still needs further research. Summary of the Invention

[0007] This application provides a communication method, apparatus, and system for enabling access network devices to obtain the context of terminal devices based on core network devices, thereby facilitating the access network devices to restore the terminal devices from an inactive state to a connected state according to the context of the terminal devices, thus improving communication efficiency.

[0008] In a first aspect, embodiments of this application provide a communication method, which can be executed by a first communication device. Unless otherwise specified, the "first communication device" in this application can refer to a first communication equipment (e.g., a terminal device), a component within the first communication equipment (e.g., a processor, chip, or chip system), or a logic module or software capable of implementing all or part of the functions of the first communication equipment. For example, in the method provided in the first aspect, the terminal device receives a first message from a first access network device, the first message being used to instruct the terminal device to enter an inactive state; and sends a second message to a second access network device, the second message being used to request the restoration of the RRC connection of the terminal device, the second message including first identification information, the first identification information including the identifier of the terminal device and the identifier of the core network device; wherein, the first identification information is used to obtain the context of the terminal device based on the core network device.

[0009] Using the above method, since the second message includes the first identification information, the second access network device can find the corresponding core network device based on the first identification information, and the core network device can find the corresponding anchor access network device based on the first identification information. This enables the core network device to obtain the context of the terminal device, which facilitates the second access network device to restore the terminal device from the inactive state to the connected state based on the context of the terminal device, thereby improving communication efficiency.

[0010] In one possible design, the method further includes: determining that the first access network device and the second access network device cannot communicate.

[0011] In this way, the terminal device itself can perform a judgment to determine whether to carry the first identification information in the second message, thereby facilitating compatibility with existing designs. For example, when the first access network device and the second access network device can communicate with each other, the second message can carry the I-RNTI so that the context of the terminal device can be obtained based on the communication interface between the first access network device and the second access network device.

[0012] In one possible design, determining that the first access network device and the second access network device cannot communicate includes: receiving first information from the first access network device, the first information indicating a first area; if the terminal device is located in the first area, then determining that the first access network device and the second access network device cannot communicate; or, receiving second information from the first access network device, the second information indicating M access network devices capable of communicating with the first access network device, where M is an integer greater than or equal to 1; if the second access network device is not among the M access network devices, then determining that the first access network device and the second access network device cannot communicate; or, receiving third information from the second access network device, the third information indicating N access network devices capable of communicating with the second access network device, where N is an integer greater than or equal to 1; if the first access network device is not among the N access network devices, then determining that the first access network device and the second access network device cannot communicate.

[0013] In one possible design, the method further includes: receiving fourth information from the second access network device, the fourth information being used to instruct the terminal device to report the first identification information.

[0014] Thus, the second access network device can instruct the terminal device whether to report the first identification information, and the terminal device does not need to perform a judgment operation.

[0015] In one possible design, the identifier of the terminal device is a first identifier assigned to the terminal device by the core network device.

[0016] In one possible design, the method further includes: receiving the first identification information from the core network device.

[0017] In one possible design, the identifier of the terminal device is a second identifier assigned to the terminal device by the first access network device, and the first identifier information also includes the identifier of the first access network device.

[0018] In one possible design, the method further includes: receiving the first identification information from the first access network device.

[0019] In one possible design, the method further includes: receiving second identification information from the first access network device, the second identification information including the identifier of the terminal device and the identifier of the first access network device, the second identification information being used to obtain the context of the terminal device based on the communication interface between the first access network device and the second access network device; and obtaining the first identification information based on the second identification information and the identifier of the core network device.

[0020] In one possible design, the method further includes: receiving fifth information from the second access network device, the fifth information indicating at least one core network device connected to the second access network device, the at least one core network device including the core network device; and determining an identifier of the core network device based on the fifth information, the identifier of the core network device being an index of the core network device in the at least one core network device.

[0021] In one possible design, the method further includes sending a sixth message to the second access network device, the sixth message indicating that the first identification information includes the identifier of the terminal device and the identifier of the core network device.

[0022] In this way, by sending the sixth message through the terminal device, the second access network device can accurately identify the specific content of the identification information carried in the second message.

[0023] Secondly, embodiments of this application provide a communication method, which can be executed by a second communication device. Unless otherwise specified, the "second communication device" in this application can refer to a second communication equipment (e.g., a second access network device), a component within the second communication equipment (e.g., a processor, chip, or chip system), or a logic module or software capable of implementing all or part of the functions of the second communication equipment. For example, in the method provided in the second aspect, the second access network device receives a second message from a terminal device, the second message being used to request the restoration of the RRC connection of the terminal device. The second message includes first identification information, the first identification information including the identifier of the terminal device and the identifier of the core network device. Based on the identifier of the core network device, a third message is sent to the core network device, the third message including the identifier of the terminal device, the third message being used to request the acquisition of the context of the terminal device.

[0024] In one possible design, the identifier of the terminal device is a first identifier assigned to the terminal device by the core network device; or, the identifier of the terminal device is a second identifier assigned to the terminal device by the first access network device, and the third message also includes the identifier of the first access network device.

[0025] In one possible design, the identifier of the core network device is the local identifier of the core network device; sending a third message to the core network device based on the identifier of the core network device includes: determining the global identifier of the core network device based on the local identifier of the core network device; and sending the third message to the core network device based on the global identifier of the core network device.

[0026] Thus, since the second access network device cannot directly identify the local identifier of the core network device, the second access network device can determine the global identifier of the core network device based on the local identifier of the core network device, so as to know which core network device to send the third message to.

[0027] In one possible design, determining the global identifier of the core network device based on its local identifier includes: obtaining first correspondence information, which indicates the correspondence between the local identifier of the core network device and the global identifier of the core network device; and determining the global identifier of the core network device based on its local identifier and the first correspondence information.

[0028] In one possible design, the method further includes: sending fifth information, the fifth information including a global identifier of at least one core network device to which the second access network device is connected, the at least one core network device including the core network device; wherein, the local identifier of the core network device is an index of the core network device in the at least one core network device.

[0029] In one possible design, the method further includes receiving a sixth message from the core network device, the sixth message including the identifier of the terminal device and the context of the terminal device.

[0030] In one possible design, the method further includes: receiving a seventh message from the terminal device, the seventh message indicating that the RRC connection of the terminal device has been restored; and sending an eighth message to the core network device according to the seventh message, the eighth message including the identifier of the terminal device, the eighth message indicating that the context of the terminal device stored in the first access network device is deleted.

[0031] Thirdly, embodiments of this application provide a communication method that can be executed by a third communication device. Unless otherwise specified, the "third communication device" in this application can refer to a third communication equipment (e.g., a core network device), a component within the third communication equipment (e.g., a processor, chip, or chip system), or a logic module or software capable of implementing all or part of the functions of the third communication equipment. For example, in the method provided in the third aspect, a third message is received from a second access network device, the third message including the identifier of the terminal device, the third message being used to request the context of the terminal device; based on the third message, a fourth message is sent to a first access network device, the fourth message being used to request the context of the terminal device, the first access network device storing the context of the terminal device.

[0032] In one possible design, the identifier of the terminal device is a first identifier assigned to the terminal device by the core network device.

[0033] In one possible design, sending a fourth message to the first access network device according to the third message includes: determining a third identifier of the terminal device and the first access network device based on the first identifier; and sending the fourth message to the first access network device, the fourth message including the third identifier.

[0034] Thus, since the first access network device cannot recognize the first identifier, the core network device can determine the third identifier based on the first identifier and carry the third identifier in the fourth message.

[0035] In one possible design, the method further includes: receiving a fifth message from the first access network device, the fifth message including the third identifier and the context of the terminal device; and sending a sixth message to the second access network device, the sixth message including the first identifier and the context of the terminal device.

[0036] In one possible design, the identifier of the terminal device is a second identifier assigned to the terminal device by the first access network device, and the third message also includes the identifier of the first access network device.

[0037] In one possible design, the identifier of the first access network device is the local identifier of the first access network device; according to the third message, a fourth message is sent to the first access network device, including: determining the global identifier of the first access network device based on the local identifier of the first access network device; and sending the fourth message to the first access network device based on the global identifier of the first access network device.

[0038] Thus, since the core network equipment cannot directly identify the local identifier of the first access network equipment, the core network equipment can determine the global identifier of the first access network equipment based on the local identifier of the first access network equipment, so as to know which access network equipment is the anchor access network equipment.

[0039] In one possible design, determining the global identifier of the first access network device based on its local identifier includes: obtaining second correspondence information, which indicates the correspondence between the local identifier of the first access network device and the global identifier of the first access network device; and determining the global identifier of the first access network device based on its local identifier and the second correspondence information.

[0040] In one possible design, the identifier of the first access network device is the global identifier of the first access network device; sending a fourth message to the first access network device according to the third message includes: sending the fourth message to the first access network device according to the global identifier of the first access network device.

[0041] In this way, the core network equipment can directly determine which access network device is the anchor access network device based on the global identifier of the first access network device.

[0042] In one possible design, the fourth message includes the second identifier.

[0043] In this way, the first access network device can know which terminal device's context is being requested based on the second identifier.

[0044] In one possible design, the method further includes: receiving a fifth message from the first access network device, the fifth message including the second identifier and the context of the terminal device; and sending a sixth message to the second access network device, the sixth message including the second identifier and the context of the terminal device.

[0045] In one possible design, the method further includes: receiving an eighth message, the eighth message including an identifier of the terminal device, the eighth message being used to indicate the deletion of the context of the terminal device stored in the first access network device; and sending a ninth message to the first access network device according to the eighth message, the ninth message being used to indicate the deletion of the context of the terminal device stored in the first access network device.

[0046] In one possible design, the method further includes: after determining that the timer has timed out, sending a ninth message to the first access network device, the ninth message being used to instruct the deletion of the context of the terminal device stored in the first access network device; wherein the start time of the timer is the time of receiving the third message, or the time of sending the fourth message, or the time of receiving the fifth message, or the time of sending the sixth message.

[0047] Fourthly, this application provides a communication device that has the functions involved in any of the first to third aspects described above. For example, the communication device includes modules, units, or means corresponding to the operations involved in any of the first to third aspects described above. The functions, units, or means can be implemented by software, or by hardware, or by hardware executing corresponding software.

[0048] In one possible design, the communication device includes a processing unit and a communication unit. The communication unit can be used to transmit and receive signals to enable communication between the communication device and other devices. The processing unit can be used to perform some internal operations of the communication device. The functions performed by the processing unit and the communication unit can correspond to the operations involved in any of the first to third aspects described above.

[0049] In one possible design, the communication device includes a processor that can be coupled to a memory. The memory can store necessary computer programs or instructions for implementing the functions involved in any of the first to third aspects described above. The processor can execute the computer programs or instructions stored in the memory, causing the communication device to implement the methods in any of the possible designs or implementations of the first to third aspects described above when the computer programs or instructions are executed.

[0050] In one possible design, the communication device includes a processor and a memory, the memory of which may store necessary computer programs or instructions for implementing the functions involved in any of the first to third aspects described above. The processor may execute the computer programs or instructions stored in the memory, and when the computer programs or instructions are executed, cause the communication device to implement the methods in any possible design or implementation of the first to third aspects described above.

[0051] In one possible design, the communication device includes a processor and an interface circuit, wherein the processor is used to communicate with other devices through the interface circuit and to execute the methods in any possible design or implementation of the first to third aspects described above.

[0052] Understandably, in the fourth aspect mentioned above, the processor can be implemented in hardware or software. When implemented in hardware, the processor can be a logic circuit, integrated circuit, etc.; when implemented in software, the processor can be a general-purpose processor that reads software code stored in memory. Furthermore, there can be one or more processors, and one or more memories. The memory can be integrated with the processor, or the memory and processor can be separate. In specific implementations, the memory can be integrated with the processor on the same chip, or it can be set on different chips. This application does not limit the type of memory or the arrangement of the memory and processor.

[0053] Fifthly, this application provides a communication system that may include a first communication device and a second communication device; wherein the first communication device is used to perform the method described in the first aspect, and the second communication device is used to perform the method described in the second aspect. Optionally, the communication system may further include a third communication device, which is used to perform the method described in the third aspect.

[0054] For example, the communication system includes a terminal device and a second access network device; the terminal device receives a first message from the first access network device, the first message being used to instruct the terminal device to enter an inactive state, and sends a second message to the second access network device; the second access network device receives the second message from the terminal device, the second message being used to request the restoration of the terminal device's RRC connection, the second message including first identification information, the first identification information including the identifier of the terminal device and the identifier of the core network device, and sends a third message to the core network device based on the identifier of the core network device, the third message including the identifier of the terminal device, the third message being used to request the acquisition of the context of the terminal device.

[0055] In one possible design, the communication system further includes a core network device that receives a third message from a second access network device and, based on the third message, sends a fourth message to a first access network device. The fourth message is used to request the context of the terminal device, and the first access network device stores the context of the terminal device.

[0056] In one possible design, the communication system further includes a first access network device that receives a fourth message and sends a fifth message based on the fourth message, the fifth message including the identifier of the terminal device and the context of the terminal device; a core network device receives the fifth message and sends a sixth message to a second access network device based on the fifth message, the sixth message including the identifier of the terminal device and the context of the terminal device.

[0057] Other further technical features can be referred to the descriptions in the first, second and third aspects above, and will not be repeated here.

[0058] In a sixth aspect, this application provides a computer-readable storage medium storing a computer program (or computer-readable instructions) in which, when a computer reads and executes some or all of the computer-readable instructions, the method in any of the possible designs in the first to third aspects described above is executed.

[0059] For example, a computer-readable storage medium can be any available medium that a computer can access. This includes, but is not limited to, non-transient computer-readable media, random-access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), CD-ROM or other optical disc storage, magnetic disk storage media, or other magnetic storage devices, or any other medium capable of carrying or storing desired program code in the form of instructions or data structures and accessible by a computer.

[0060] In a seventh aspect, this application provides a computer program product that, when read and executed by a computer, causes any of the possible designs in the first to third aspects described above to be performed.

[0061] Eighthly, this application provides a chip (or chip system) including a processor coupled to a memory storing a computer program; the processor is configured to invoke part or all of the computer program in the memory, such that any of the possible designs in the first to third aspects described above are executed. Attached Figure Description

[0062] Figure 1 is a schematic diagram of the communication system used in the embodiments of this application;

[0063] Figure 2A is a schematic diagram of a CU-DU split architecture;

[0064] Figure 2B is a schematic diagram of another CU-DU separation architecture;

[0065] Figure 3 is a schematic diagram of the relationship between TA, RNA and cell;

[0066] Figure 4 is a schematic diagram of a possible RRC recovery process;

[0067] Figure 5A is a schematic diagram of the structure of I-RNTI;

[0068] Figure 5B is a schematic diagram of the 5G-S-TMSI structure;

[0069] Figure 6 is a flowchart corresponding to the communication method provided in Embodiment 1 of this application;

[0070] Figure 7 is a flowchart of the communication method provided in Embodiment 2 of this application;

[0071] Figure 8 is a schematic diagram of the improved I-RNTI structure provided in the embodiment of this application;

[0072] Figure 9 is a flowchart corresponding to the communication method provided in Embodiment 3 of this application;

[0073] Figure 10 is a possible exemplary block diagram of the apparatus involved in the embodiments of this application;

[0074] Figure 11 is a schematic diagram of the structure of a communication device provided in an embodiment of this application. Detailed Implementation

[0075] The technical solutions in the embodiments of this application will now be described with reference to the accompanying drawings. This application will focus on various aspects, embodiments, or features of a system that may include multiple devices, components, modules, etc. It should be understood and appreciated that each system may include additional devices, components, modules, etc., and / or may not include all the devices, components, modules, etc. discussed in conjunction with the accompanying drawings. Furthermore, combinations of these solutions may also be used.

[0076] In the embodiments of this application, words such as "exemplarily" and "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design scheme described as an "example" in this application should not be construed as being more preferred or advantageous than other embodiments or design schemes. Specifically, the use of the term "example" is intended to present concepts in a concrete manner. In the embodiments of this application, "of," "corresponding, relevant," and "corresponding" may sometimes be used interchangeably, and it should be noted that their intended meanings are consistent unless their distinction is emphasized.

[0077] The technical solutions of this application can be applied to various wireless communication systems, such as Universal Mobile Telecommunications System (UMTS), Wireless Local Area Network (WLAN), short-range wireless communication systems (such as sidelink, wireless fidelity, Wi-Fi, Bluetooth, etc.), wired networks, vehicle-to-everything (V2X) communication systems, device-to-device (D2D) communication systems, vehicle-to-everything (V2X) communication systems, integrated communication and sensing systems, 4th generation (4G) mobile communication systems (such as Long Term Evolution (LTE) systems), LTE Frequency Division Duplex (FDD) systems, LTE Time Division Duplex (TDD) systems, Worldwide Interoperability for Microwave Access (WiMAX) communication systems, 5th generation (5G) mobile communication systems (such as New Radio (NR) systems), Future Communications systems, or other similar communication systems, without limitation. This application describes the communication system shown in Figure 1 as an example. When applying the technical solution of this application to other communication systems, the devices, components, modules, etc. in the embodiment can be replaced with corresponding devices, components, modules in other communication systems without limitation.

[0078] Figure 1 is a schematic diagram of the architecture of the communication system used in the embodiments of this application. As shown in Figure 1, the communication system includes an access network 100, and optionally, a core network 200.

[0079] (1) Access Network

[0080] The access network can be a radio access network (RAN), which can be an access network in the 3rd generation partnership project (3GPP), such as 4G, 5G, or future networks. RAN can also be an open access network (O-RAN or ORAN), a cloud radio access network (CRAN), or a communication network combining two or more of the above.

[0081] Access network 100 may include at least one access network device, such as 110a and 110b in Figure 1, and may also include at least one terminal device, such as 120a-120j in Figure 1. Specifically, 110a is a base station, 110b is a micro-station, 120a, 120e, 120f, and 120j are mobile phones, 120b is a car, 120c is a fuel dispenser, 120d is a home access point (HAP) deployed indoors or outdoors, 120g is a laptop computer, 120h is a printer, and 120i is a drone. The same terminal device or access network device can provide different functions in different application scenarios. For example, the mobile phones in Figure 1 are 120a, 120e, 120f and 120j. Mobile phone 120a can access base station 110a, connect to car 120b, communicate directly with mobile phone 120e and access HAP. Car 120b can access HAP and communicate directly with mobile phone 120a. Mobile phone 120f can access micro-station 110b, connect to laptop 120g and printer 120h. Mobile phone 120j can control drone 120i.

[0082] (1.1) Access network equipment

[0083] Access network equipment is a network-side device with wireless transceiver capabilities. Access network equipment can be a device within the RAN (Radio Access Network) that provides wireless communication functionality to terminal devices, and can be referred to as RAN equipment. For example, access network equipment can be a base station, an evolved NodeB (eNodeB), a transmission reception point (TRP), a next-generation NodeB (gNB) in a 5G mobile communication system, a base station in a future mobile communication system, an access node, transmission node, transceiver node, relay equipment in a WiFi system, or a small cell or micro cell with base station functionality, etc.

[0084] Access network equipment can also be modules or units that perform some of the functions of a base station. For example, it can be a central unit (CU), a distributed unit (DU), or a radio unit (RU).

[0085] For example, as shown in Figure 2A, the CU and DU can communicate via the F1 interface. The CU performs the functions of the base station's RRC and Packet Data Convergence Protocol (PDCP) layers, and can also perform the functions of the Service Data Adaptation Protocol (SDAP). The DU performs the functions of the base station's Radio Link Control (RLC) and Media Access Control (MAC) layers, and can also perform some (such as higher-level physical layer functions) or all physical layer functions. The higher-level physical layer functions include one or more of the following: forward error correction (FEC) encoding / decoding, scrambling / descrambling, or modulation / demodulation. As shown in Figure 2B, the CU can be further divided into the CU control panel (CP) (i.e., CU-CP) and the CU user panel (UP) (i.e., CU-UP). The CU-CP and CU-UP can communicate via the E1 interface. In Figure 2B, PDCP-C represents the PDCP control plane function, PDCP-U represents the PDCP user plane function, F1-C represents the F1 control plane interface, and F1-U represents the F1 user plane interface.

[0086] In addition, the RU is used to implement low-level (near radio frequency) functions of the physical layer and radio frequency functions. These low-level physical layer functions include one or more of the following: fast Fourier transform (FFT) / inverse fast Fourier transform (iFFT), digital beamforming, or extraction and filtering of the physical random access channel (PRACH). The RU is similar to a transmission reception point (TRP) or remote radio head (RRH) in 3GPP, but it includes low-level PHY functions such as FFT / iFFT or PRACH extraction. For detailed descriptions of the various protocol layers mentioned above, please refer to the relevant 3GPP technical specifications.

[0087] CU and DU can be set up separately or included in the same network element, such as in a baseband unit (BBU). RU can be included in radio frequency equipment or radio frequency units, such as in a remote radio unit (RRU), an active antenna unit (AAU), or a remote radio head (RRH).

[0088] In different systems, CU, DU, or RU may have different names, but those skilled in the art will understand their meanings. For example, in an ORAN system, CU can also be called O-CU, i.e., O-RAN central unit or O-RAN control unit; DU can also be called O-DU; and RU can also be called O-RU. Furthermore, CU-CP can also be called O-CU-CP, i.e., O-RAN central unit control plane or O-RAN control unit control plane; and CU-UP can also be called O-CU-UP, i.e., O-RAN central unit user plane or O-RAN control unit user plane. Any of the units CU (or CU-CP, CU-UP), DU, and RU in this application can be implemented through software modules, hardware modules, or a combination of software and hardware modules.

[0089] (1.2) Terminal equipment

[0090] A terminal device is a user-side device with wireless transceiver capabilities. Terminal devices can also be called terminals, user equipment (UE), mobile stations, mobile terminals, etc. Terminal devices can be widely used in various scenarios, such as device-to-device (D2D), vehicle-to-everything (V2X) communication, machine-type communication (MTC), the Internet of Things (IoT), the Industrial Internet, virtual reality, augmented reality, industrial control, autonomous driving, telemedicine, smart grids, smart furniture, smart offices, smart wearables, smart transportation, and smart cities. Terminal devices can be mobile phones, tablets, computers with wireless transceiver capabilities, wearable devices, vehicles, drones, helicopters, airplanes, ships, robots, robotic arms, smart home devices, etc. In the embodiments of this application, the device used to implement the functions of the terminal device can be the terminal device itself, or it can be a device that supports the terminal device in implementing that function, such as a chip system or a combination of devices or components that can implement the functions of the terminal device. This device can be installed in the terminal device. The embodiments of this application do not limit the specific technology or specific device form used in the terminal device.

[0091] Furthermore, access network equipment and terminal equipment can be fixed in location or mobile. They can be deployed on land, including indoors or outdoors, handheld or vehicle-mounted; they can also be deployed on water; and they can be deployed in the air on aircraft, balloons, and satellites. The embodiments of this application do not limit the application scenarios of the access network equipment and terminal equipment.

[0092] The roles of access network devices and terminal devices can be relative. For example, the helicopter or drone 120i in Figure 1 can be configured as a mobile access network device. For terminal devices 120j that access the wireless access network 100 via 120i, terminal device 120i is an access network device; however, for access network device 110a, 120i is a terminal device. That is, 110a and 120i communicate via a wireless air interface protocol. Of course, 110a and 120i can also communicate via an interface protocol between access network devices. In this case, relative to 110a, 120i is also an access network device. Therefore, both access network devices and terminal devices can be collectively referred to as communication devices. 110a and 110b in Figure 1 can be called communication devices with access network device functions, and 120a-120j in Figure 1 can be called communication devices with terminal device functions.

[0093] (2) Core Network

[0094] The core network is responsible for maintaining the subscription data of the mobile network, managing the network elements of the mobile network, and providing terminal devices with functions such as session management, mobility management, policy management, and security authentication.

[0095] Core network equipment refers to the equipment in the core network that provides service support for terminal equipment. Currently, some examples of core network equipment include: access and mobility management function (AMF) entities, session management function (SMF) entities, user plane function (UPF) entities, policy control function (PCF) entities, etc., which will not be listed here. It should be noted that in this application, entities can also be referred to as network elements; for example, an AMF entity can also be called an AMF network element, and an SMF entity can also be called an SMF network element.

[0096] AMF network elements are primarily responsible for mobility management in mobile networks, such as location updates for terminal devices, network registration, and handover.

[0097] SMF network elements are primarily responsible for session management in mobile networks, such as session establishment, modification, and release. Specific functions include assigning Internet Protocol (IP) addresses to terminal devices and selecting UPF network elements that provide packet forwarding capabilities.

[0098] PCF network elements are responsible for providing policies to AMF and SMF network elements, such as Quality of Service (QoS) policies and slice selection policies.

[0099] UPF network elements are primarily responsible for processing user packets, such as forwarding and billing.

[0100] The aforementioned network elements / functional entities can be network components in hardware devices, software functions running on dedicated hardware, or virtualized functions instantiated on a platform (e.g., a cloud platform). Optionally, the aforementioned network elements or functional entities can be implemented by one device, multiple devices working together, or different functional modules within a single device; this application embodiment does not specifically limit this. In actual deployment, the aforementioned network elements can be co-located. When two network elements are co-located, the interaction between these two network elements provided in this application embodiment becomes the internal operation of the co-located network element or can be omitted.

[0101] It should be understood that the definitions and boundaries of the access network equipment and the CN in the embodiments of this application may be the same as or different from those of the gNB and CN in the existing NR. For example, the access network equipment may only be responsible for a part of the functions in the existing NR gNB, while other functions may be merged into a part of the network elements of the CN or become independent network elements, and communicate directly with the service bus of the existing 5G core network.

[0102] The network architecture and business scenarios described in this application are intended to more clearly illustrate the technical solutions of the embodiments of this application, and do not constitute a limitation on the technical solutions provided in the embodiments of this application. As those skilled in the art will know, with the evolution of network architecture and the emergence of new business scenarios, the technical solutions provided in the embodiments of this application are also applicable to similar technical problems.

[0103] The following explanations address the relevant terms used in the embodiments of this application. These explanations are intended to make the embodiments of this application easier to understand and should not be construed as strict limitations on the terms within the scope of protection claimed in this application.

[0104] (1) Inactive state

[0105] In the communication system shown in Figure 1, the state of a terminal device can include RRC connected state, RRC idle state, and RRC inactive state. The purpose of the inactive state is to allow the terminal device to quickly return to the RRC connected state without needing to reconnect. Similar to the idle state, the terminal device in the inactive state can only receive content from the common search space (such as paging messages, broadcast messages, etc.).

[0106] For example, after a terminal device enters the connected state in cell a1 of the first access network device, the first access network device can instruct the terminal device to switch from the connected state to the inactive state. For instance, the first access network device sends an RRC release message to the terminal device, which instructs the terminal device to enter the inactive state; correspondingly, the terminal device enters the inactive state after receiving the RRC release message. The RRC release message includes the terminal device's context ID, which can be called the inactive-radio network temporary identity (I-RNTI). The RRC connection between the inactive terminal device and the first access network device is disconnected, but the first access network device still stores the terminal device's context. The first access network device can be called an anchor access network device, an anchor gNB, or the terminal device's last serving gNB.

[0107] (2) RAN-based notification area

[0108] For UEs in an inactive state, to further reduce paging message transmission overhead, the concept of a RAN-based notification area (RNA), which is smaller than the tracking area (TA), is introduced. An RNA can include multiple cells. As shown in Figure 3, cells can form a larger RNA, and RNAs can form a larger TA.

[0109] The first access network device (i.e., the anchor access network device) can configure the RNA for the terminal device and send RNA configuration information to the terminal device. For example, the RRC release message sent by the first access network device to the terminal device may include RNA configuration information. The RNA may include multiple cells; for example, the RNA configuration information may include the identifiers of multiple cells. These multiple cells may belong to one access network device or multiple access network devices. For instance, if the RNA includes cell a1 of the first access network device and cell b1 of the second access network device, then the RNA configuration information may include the identifiers of cell a1 and cell b1.

[0110] (3) RRC recovery process

[0111] Inactive terminal devices support the RRC resume process. There are several scenarios in which a terminal device can initiate the RRC resume process, such as when the terminal device needs to transmit data or signaling, or when the terminal device needs to initiate an RNA update (e.g., when the terminal device's RNA timer times out or the terminal device moves out of the RNA), or when the terminal device receives a paging message.

[0112] The following example illustrates a possible RRC recovery process, using the scenario where "the first access network device serves as the anchor access network device for the terminal device, the terminal device moves from the coverage area of ​​the first access network device to the coverage area of ​​the second access network device, and initiates an RRC recovery procedure." Figure 4 illustrates this process. As shown in Figure 4, the procedure may include:

[0113] S401, the first access network device sends an RRC release message to the terminal device to instruct the terminal device to enter the inactive state; accordingly, the terminal device receives the RRC release message and enters the inactive state.

[0114] For example, the RRC release message includes the terminal device's I-RNTI.

[0115] S402, the terminal device sends an RRC recovery request message to the second access network device; correspondingly, the second access network device receives the RRC recovery request message.

[0116] For example, the RRC recovery request message includes the terminal device's I-RNTI.

[0117] S403, after receiving the RRC recovery request message, the second access network device sends a retrieve UE context request message to the first access network device through the communication interface (i.e., the Xn interface) between the second access network device and the first access network device; correspondingly, the first access network device can receive the retrieve UE context request message.

[0118] Here, after parsing the identifier of the first access network device in the I-RNTI (see the introduction of I-RNTI below), the second access network device sends a UE context request message to the first access network device. The UE context request message may include the terminal device's I-RNTI, and the first access network device can obtain the context of the terminal device based on the I-RNTI.

[0119] S404, the first access network device sends a retrieve UE context response message to the second access network device through the Xn interface; correspondingly, the second access network device receives the retrieve UE context response message.

[0120] Here, obtaining the UE context response message may include the context of the terminal device, and thus the second access network device can obtain the context of the terminal device.

[0121] S405, the second access network device sends an RRC recovery message to the terminal device; correspondingly, the terminal device receives the RRC recovery message and restores the RRC connection.

[0122] S406, the terminal device sends an RRC recovery completion message to the second access network device; correspondingly, the second access network device receives the RRC recovery completion message.

[0123] S407, the second access network device performs path switching, for example, the second access network device sends a path switching request message to the AMF network element, and the AMF network element receives the path switching request message accordingly.

[0124] S408, the AMF network element sends a path switching response message to the second access network device, and the second access network device receives the path switching response message and completes the path switching.

[0125] Here, path switching refers to changing the data transmission path of the terminal device from "UPF network element - first access network device - terminal device" to "UPF network element - second access network device - terminal device". In other words, after path switching, downlink data can be sent from the UPF network element to the second access network device, and then from the second access network device to the terminal device; uplink data can be sent from the terminal device to the second access network device, and then from the second access network device to the UPF network element.

[0126] Optionally, the second access network device can also send address indication information to the first access network device, indicating the address at which the first access network device forwards data (i.e., downlink data). If the first access network device receives downlink data from the terminal device from the UPF network element before path switching, it can forward the downlink data to the second access network device according to the address indication information, and the second access network device will then send it to the terminal device.

[0127] S409, the second access network device sends a context release message to the first access network device through the Xn interface. The context release message includes the I-RNTI of the terminal device. Correspondingly, the first access network device receives the context release message and releases the context of the terminal device.

[0128] It is understood that the process shown in Figure 4 is only one possible example, and the above process may include other possible steps, without any specific limitation.

[0129] (4) I-RNTI

[0130] I-RNTI may include the identifier of the access network device (such as the local NG-RAN node identifier or the NG-RAN node address index) and the UE-specific reference. Optionally, it may also include a profile identity. Regarding the identifier of the access network device, this embodiment will use the Local NG-RAN Node Identifier as an example in the following description. The Local NG-RAN Node Identifier can be replaced with the NG-RAN node address index.

[0131] The UE-specific reference is an identifier assigned by the anchor access network device to the terminal device. Therefore, the anchor access network device can recognize this identifier, while the AMF network element cannot directly recognize it. The Local NG-RAN Node Identifier is an identifier used to uniquely identify the access network device within the local network. Profile Identity indicates the length of the Local NG-RAN Node Identifier and the length of the UE-specific reference.

[0132] Figure 5A shows a possible structure of I-RNTI. As shown in Figure 5A, I-RNTI includes a profile identifier, an access network device identifier, and a UE-specific identifier. For example, I-RNTI has a total of 40 bits, and the Profile Identity can include 2 bits. Different values ​​of these 2 bits are used to represent the length of the Local NG-RAN Node Identifier and the length of the UE-specific reference in the I-RNTI.

[0133] For example, a Profile Identity of 00 indicates that the Local NG-RAN Node Identifier is 12 bits long and the UE-specific reference is 26 bits long.

[0134] The Profile Identity is 01, indicating that the Local NG-RAN Node Identifier is 15 bits long and the UE specific reference is 23 bits long.

[0135] The Profile Identity value is 10, indicating that the Local NG-RAN Node Identifier is 18 bits long and the UE-specific reference is 20 bits long.

[0136] The Profile Identity is 11, which means that the Local NG-RAN Node Identifier is 21 bits long and the UE specific reference is 17 bits long.

[0137] (5) 5G-S-TMSI

[0138] 5G-S-TMSI (5G system temporary mobile subscriber identity) is a temporary identifier assigned to a terminal device in a 5G network. It is used to replace the terminal device's permanent identifier for communication on the radio interface, protecting user privacy and identity information. The 5G-S-TMSI is assigned to the terminal device by the AMF (Active Mobile Provider) network element. For example, after the terminal device completes the registration process, the AMF network element assigns a 5G-S-TMSI and sends it to the terminal device.

[0139] Figure 5B shows a possible structure of 5G-S-TMSI. As shown in Figure 5B, 5G-S-TMSI consists of 48 bits, specifically three parts: AMF Set ID, AMF Pointer, and 5G temporary mobile subscriber identity (5G-TMSI). The AMF Set ID comprises 10 bits, the AMF Pointer comprises 6 bits, and the 5G-TMSI comprises 32 bits. The AMF Set ID and AMF Pointer are used to identify AMF network elements. 5G-TMSI is a temporary value that uniquely identifies the terminal device within the AMF network element. AMF network elements can recognize 5G-TMSI, but access network devices cannot.

[0140] As described in the RRC recovery process above, the first and second access network devices communicate through the Xn interface, enabling the second access network device to obtain the context of the terminal device. However, in some scenarios, different access network devices cannot communicate through the Xn interface. For example, the Xn interface may not exist between different access network devices, or although it exists, it may be faulty, thus preventing communication through the Xn interface.

[0141] Based on this, embodiments of this application will study the relevant implementation of the second access network device obtaining the context of the terminal device. For example, embodiments of this application provide a communication method, apparatus, and system for obtaining the context of the terminal device based on the core network device, so that the second access network device can also obtain the context of the terminal device when communication between the first and second access network devices is impossible.

[0142] Here, we will first introduce the identifiers of the terminal device, the core network device, and the first access network device in the embodiments of this application.

[0143] (1) Identification of terminal equipment

[0144] The first identifier, the second identifier, and the third identifier in the embodiments of this application can be collectively referred to as the identifier of the terminal device.

[0145] The first identifier is the identifier assigned to the terminal device by the core network equipment (such as the AMF network element), such as the first identifier being 5G-TMSI.

[0146] The second identifier is the identifier assigned to the terminal device by the first access network device (i.e., the anchor access network device). For example, the second identifier is the UE specific reference in the I-RNTI.

[0147] The third identifier is an identifier pair assigned to the terminal device by the core network equipment (such as the AMF network element) and the first access network equipment. For example, the third identifier is the UE NGAP pair ID. Exemplarily, the UE NGAP pair ID includes the NG-RAN UE NGAP ID and the AMF UE NGAP ID. The NG-RAN UE NGAP ID and the AMF UE NGAP ID can be used in pairs. The NG-RAN UE NGAP ID is used to uniquely identify the UE on the NG interface (the interface between the NG-RAN and the core network). The NG-RAN UE NGAP ID is assigned by the first access network equipment and communicated to the AMF. The AMF UE NGAP ID is used to identify the terminal device on the NG interface and is assigned by the AMF network element.

[0148] (2) Identification of core network equipment

[0149] In this embodiment of the application, the local identifier and the global identifier of the core network device are collectively referred to as the identifier of the core network device.

[0150] Taking AMF network elements as an example, the global identifier of an AMF network element can be called a glocal AMF Identifier. For instance, the global identifier of an AMF network element includes the AMF Set ID and the AMF Pointer. Optionally, it also includes the AMF Region ID and / or the identifier of the public land mobile network (PLMN) to which the AMF network element belongs. The local identifier of an AMF network element can be an index of the AMF network element, such as an AMF index or Local AMF Identifier. The number of bits included in the local identifier of an AMF network element is less than the number of bits included in the global identifier of the AMF network element; for example, the local identifier of an AMF network element may include 8 bits or fewer.

[0151] (3) Identification of the first access network device

[0152] In this embodiment of the application, the local identifier and the global identifier of the first access network device are collectively referred to as the identifier of the first access network device.

[0153] The local identifier of the first access network device can be the Local NG-RAN Node Identifier in the I-RNTI. Alternatively, considering that the Local NG-RAN Node Identifier of different access network devices within different RNAs may be the same, the local identifier of the first access network device may include both the Local NG-RAN Node Identifier and the RNA ID.

[0154] The global identifier of the first access network device can be an identifier assigned to it by the operation, administration, and maintenance (OAM) network element, such as the Global RAN Node ID or Global gNB ID. Core network devices connected to the first access network device can recognize its global identifier, but cannot directly recognize its local identifier.

[0155] It is understood that the "local identifier" and "global identifier" in the embodiments of this application are introduced to distinguish the different identifiers of the first access network device or the core network device. The local identifier and the global identifier are relative concepts. The local identifier identifies the first access network device or the core network device within a local scope (a relatively small scope), while the global identifier identifies the first access network device or the core network device within a global scope (a relatively large scope). The global identifier is relative to the local identifier and is not an absolutely globally universal identifier. Its global scope depends on the specific network architecture; for example, it could be a regional network, an operator network, or a larger network scope agreed upon by multiple operator networks, and is not specifically limited.

[0156] The communication method provided in this application is described below with reference to specific embodiments. The communication method provided in this application involves at least one communication device, such as a first communication device, a second communication device, and a third communication device, and optionally, a fourth communication device. The first communication device is a terminal device or a component of a terminal device, such as a chip or chip system disposed in the terminal device; the second communication device is a second access network device or a component of a second access network device, such as a chip or chip system disposed in the second access network device; the third communication device is a core network device (such as an AMF network element) or a component of a core network device, such as a chip or chip system disposed in the core network device; the fourth communication device is a first access network device or a component of a first access network device, such as a chip or chip system disposed in the first access network device; the specific details are not limited thereto. In this application embodiment, the example of "the first communication device being a terminal device, the second communication device being a second access network device, the third communication device being a core network device, and the fourth communication device being a first access network device" is used for description.

[0157] Example 1

[0158] Figure 6 is a flowchart illustrating the communication method provided in Embodiment 1 of this application. As shown in Figure 6, the process may include:

[0159] S601, the first access network device sends a first message to the terminal device, the first message being used to instruct the terminal device to enter the inactive state; accordingly, the terminal device receives the first message and enters the inactive state.

[0160] Here, the first access network device is the anchor access network device of the terminal device. After the terminal device enters the inactive state, the first access network device still stores the context of the terminal device.

[0161] For example, the first message is an RRC release message. The first message includes second identification information, which includes a second identifier of the terminal device (such as a UE specific reference) and a local identifier of the first access network device (such as a Local NG-RAN Node Identifier). The second identification information is used to obtain the context of the terminal device based on the communication interface between the first access network device and the second access network device. That is, the second identification information is used to obtain the context of the terminal device based on the Xn interface.

[0162] Optionally, the second identification information may also include other possible information, without limitation. For example, if the second identification information is I-RNTI, then the second identification information may also include Profile Identity.

[0163] S602, the terminal device sends a second message to the second access network device, the second message being used to request the restoration of the terminal device's RRC connection; correspondingly, the second access network device receives the second message.

[0164] For example, if a terminal device determines that it needs to initiate an RRC recovery process, and if the terminal device is currently within the coverage area of ​​a second access network device, the terminal device can send a second message to the second access network device. There are several scenarios in which a terminal device determines that it needs to initiate an RRC recovery process, as described above.

[0165] (1) Introduce the second message.

[0166] For example, the second message is an RRC recovery request message. The second message includes first identification information, and may also include other possible information, without limitation. The first identification information includes the terminal device's first identifier (e.g., 5G-TMSI) and the core network device's local identifier (e.g., AMF index). The first identification information can be called short 5G-S-TMSI, or other names, without limitation. The first identification information is used to obtain the terminal device's context based on the core network device. The first identification information can be assigned and sent to the terminal device by the core network device. For example, after the terminal device accesses the network (i.e., the terminal device is in a connected state), the core network device can send the first identification information to the terminal device through the access network device (such as the first access network device mentioned above).

[0167] As mentioned above, the first identifier (such as 5G-TMSI) assigned by the core network equipment to the terminal equipment includes 32 bits. When the local identifier of the core network equipment includes 8 bits, the first identifier information has a total of 40 bits, which is the same length as the I-RNTI. Therefore, the method designed in this embodiment does not change the length of the identifier information carried in the RRC recovery request message, thus having good compatibility.

[0168] (2) The implementation of the terminal device sending the second message to the second access network device is introduced.

[0169] For example, when the terminal device determines that the first access network device and the second access network device cannot communicate, it sends a second message (i.e., an RRC recovery request message) to the second access network device, the RRC recovery request message including first identification information; when the terminal device determines that the first access network device and the second access network device can communicate (i.e., can communicate through the Xn interface), it sends an RRC recovery request message to the second access network device, the RRC recovery request message including second identification information (such as I-RNTI).

[0170] The inability to communicate between the first access network device and the second access network device can mean that they cannot communicate via the Xn interface. This can be replaced by: the first access network device being unreachable from the perspective of the second access network device; or the absence of a communication interface (i.e., the Xn interface) between them; or a failure of the communication interface between them.

[0171] There are several ways for the terminal device to determine that the first access network device and the second access network device cannot communicate.

[0172] In one possible implementation, the terminal device receives first information from a first access network device. This first information indicates a first area; for example, it may be carried in a first message or other possible messages. If the terminal device is located in the first area, it can determine that the first access network device and the second access network device cannot communicate. The first information may include geographical location information (such as latitude, longitude, altitude, etc.) or information about the cells included in the first area.

[0173] For example, the first area may be determined by the first access network device based on the coverage of access network devices that can communicate with the first access network device, or it may be pre-configured in the first access network device, without any specific limitation.

[0174] As another possible implementation, the terminal device receives second information from the first access network device. This second information indicates M access network devices capable of communicating with the first access network device, where M is an integer greater than or equal to 1. For example, the second information may include the identifiers of the M access network devices, and may be carried within the first message or other possible messages. If the second access network device is not among the M access network devices, it is determined that the first access network device and the second access network device cannot communicate.

[0175] As another possible implementation, the terminal device receives third information from the second access network device. This third information indicates N access network devices that can communicate with the second access network device, where N is an integer greater than or equal to 1. For example, the third information includes the identifiers of the N access network devices, is carried in a system message from the second access network device, or other possible messages. If the first access network device is not among the N access network devices, it is determined that the first access network device and the second access network device cannot communicate.

[0176] Optionally, the terminal device receives capability information from the second access network device. This capability information indicates that the second access network device supports obtaining the terminal device's context based on the core network device. The capability information may be carried in a system message, message 2 (msg2) of the random access procedure, or other possible messages. Therefore, if the terminal device determines that the first and second access network devices cannot communicate and that the second access network device supports obtaining the terminal device's context based on the core network device, it may send a second message, namely an RRC recovery request message, to the second access network device. The RRC recovery request message includes the first identification information. If the terminal device determines that the first and second access network devices cannot communicate and that the second access network device does not support obtaining the terminal device's context based on the core network device, the terminal device may choose not to send an RRC recovery request message, or the terminal device may send an RRC recovery request message, and upon receiving the RRC recovery request message, the second access network device will release the terminal device to an idle state, allowing the terminal device to subsequently enter the RRC connected state from the idle state.

[0177] Optionally, as described above, the RRC recovery request message sent by the terminal device may carry first identification information or second identification information, and the first and second identification information have the same length. Therefore, the terminal device can indicate to the second access network device which specific identification information is carried. For example, the terminal device sends a sixth message to the second access network device, the sixth message indicating that the identification information carried in the RRC recovery request message includes the identifier of the terminal device and the identifier of the core network device, i.e., the identification information carried in the RRC recovery request message is the first identification information; or, the sixth message indicating that the identification information carried in the RRC recovery request message is the second identification information. The sixth message may be carried in a second message, such as in the resume cause field of the second message, or it may be carried in other possible messages.

[0178] S603, the second access network device sends a third message to the core network device based on the second message. The third message is used to request the context of the terminal device; correspondingly, the core network device receives the third message. Here, we take the example where the second message includes the first identification information.

[0179] For example, the third message includes a first identifier of the terminal device, such as 5G-TMSI; or, the third message includes first identifier information.

[0180] For example, since the second access network device cannot directly identify the local identifier of the core network device, it can determine the global identifier (such as AMF Set ID and AMF Pointer) of the core network device based on the local identifier, and then send a third message to the core network device based on the global identifier. For instance, the core network device can maintain a correspondence between its local identifier and its global identifier, and send first correspondence information to the second access network device. This first correspondence information indicates the correspondence between the core network device's local identifier and its global identifier; subsequently, the second access network device can determine the core network device's global identifier based on its local identifier and the first correspondence information. Alternatively, the second access network device can also obtain the first correspondence information from the OAM network element.

[0181] The correspondence between the local identifier and the global identifier of a core network device can be one-to-one. For example, the local identifier of core network device A corresponds to the global identifier of core network device A, and the local identifier of core network device B corresponds to the global identifier of core network device B. Since the local identifier of a core network device consists of 8 bits, and the global identifier of a core network device consists of 16 bits (meaning the number of local identifiers is less than the number of global identifiers), when there is a one-to-one correspondence between the local identifier and the global identifier of a core network device, the local identifier corresponds to a portion of the global identifier.

[0182] Alternatively, it can be a one-to-many relationship. For example, the global identifier of core network device A and the global identifier of core network device B correspond to the same local identifier, meaning that the local identifiers of core network device A and core network device B are identical. In this case, the second access network device determines the global identifiers of multiple corresponding core network devices based on the local identifiers of the core network devices. Then, the second access network device can send a third message to each of these multiple core network devices based on their global identifiers, attempting to obtain the context of the terminal device for each core network device.

[0183] S604, the core network device sends a fourth message to the first access network device based on the third message. The fourth message is used to request the context of the terminal device. Accordingly, the first access network device receives the fourth message.

[0184] When the terminal device is inactive, although the RRC connection between the terminal device and the first access network device is released, the terminal device still maintains a connection with the core network device. This means the core network device stores relevant information about the terminal device, such as its first identifier, third identifier, and the identifier of the anchor access network device. Therefore, the core network device can determine the third identifier of the terminal device and the anchor access network device (i.e., the first access network device) based on the first identifier (e.g., 5G-TMSI) in the third message, and then send a fourth message to the first access network device. Since the first access network device cannot recognize the first identifier of the terminal device, the fourth message can include the third identifier of the terminal device (which the first access network device can recognize). Furthermore, the first access network device can determine the corresponding second identifier / I-RNTI based on the third identifier, and then obtain the context of the terminal device based on the second identifier / I-RNTI.

[0185] Optionally, the above method may further include some or all of the steps in S605 to S610.

[0186] S605, the first access network device sends a fifth message to the core network device according to the fourth message. The fifth message includes the third identifier of the terminal device and the context of the terminal device; correspondingly, the core network device receives the fifth message. The fifth message is a response message to the fourth message.

[0187] S606, the core network device sends a sixth message to the second access network device. The sixth message includes the first identifier of the terminal device and the context of the terminal device; accordingly, the second access network device receives the sixth message.

[0188] For example, if the third message includes the first identifier of the terminal device, then the sixth message here may include the first identifier of the terminal device and the context of the terminal device; if the third message includes the first identifier information, then the sixth message here may include the first identifier information and the context of the terminal device.

[0189] S607, the second access network device sends an RRC recovery message to the terminal device; correspondingly, the terminal device receives the RRC recovery message and restores the RRC connection.

[0190] For example, after obtaining the context of the terminal device, if the second access network device determines to restore the RRC connection of the terminal device, it sends an RRC restoration message to the terminal device. In other examples, the second access network device may choose not to restore the RRC connection of the terminal device.

[0191] S608, the terminal device sends a seventh message (such as an RRC recovery completion message) to the second access network device to indicate that the RRC connection of the terminal device has been restored; correspondingly, the second access network device receives the RRC recovery completion message.

[0192] S609, the second access network device sends an eighth message to the core network device according to the seventh message. The eighth message includes first identification information and is used to indicate the deletion of the context of the terminal device stored by the first access network device. Accordingly, the core network device receives the eighth message.

[0193] S610, the core network device sends a ninth message to the first access network device according to the eighth message. The ninth message includes the third identifier of the terminal device and is used to indicate the deletion of the context of the terminal device stored in the first access network device. Accordingly, the first access network device receives the ninth message and determines the corresponding second identifier / I-RNTI according to the third identifier in the ninth message, and then deletes the context of the terminal device according to the second identifier / I-RNTI.

[0194] The above steps use the example of "the core network device sending a ninth message to the first access network device based on the eighth message sent by the second access network device." In other examples, the core network device can also send a ninth message to the first access network device after determining that the timer has expired. The start time of the timer can be the time when the third message was received, or the time when the fourth message was sent, or the time when the fifth message was received, or the time when the sixth message was sent. The duration of the timer can be pre-configured or predefined, and is not specifically limited.

[0195] For example, the ninth message can be called the UE context release command.

[0196] Optionally, the above method flow may also include other possible steps, such as the step of the second access network device performing path switching, or the first access network device deleting the context of the terminal device and sending a tenth message to the core network device, which may be called the UE context release complete message.

[0197] Using the above method, a first identification information assigned to the terminal device by the core network device is introduced. The terminal device carries the first identification information in the RRC recovery request message. Therefore, the second access network device can obtain the context of the terminal device based on the core network device. This ensures that even when the first and second access network devices cannot communicate, the second access network device can still obtain the context of the terminal device. Specifically, the first identification information includes a first identifier assigned to the terminal device by the core network device and a local identifier of the core network device. The second access network device can locate the corresponding core network device based on the local identifier of the core network device and send a third message. The core network device can locate the corresponding anchor access network device based on the first identifier and send a fourth message to obtain the context of the terminal device.

[0198] Example 2

[0199] Figure 7 is a flowchart illustrating the communication method provided in Embodiment 2 of this application. As shown in Figure 7, the process may include:

[0200] S701, the first access network device sends a first message to the terminal device, the first message being used to instruct the terminal device to enter the inactive state; accordingly, the terminal device receives the first message and enters the inactive state.

[0201] Here, the first access network device is the anchor access network device of the terminal device. After the terminal device enters the inactive state, the first access network device still stores the context of the terminal device. For example, the first message is an RRC release message. The contents of the first message are described below in conjunction with implementation methods 1 to 3.

[0202] Implementation Method 1: The first message includes first identification information, which includes the second identifier of the terminal device (e.g., UE specific reference), the local identifier of the first access network device (e.g., Local NG-RAN Node Identifier), and the local identifier of the core network device (e.g., AMF index). Optionally, it may also include other possible information, such as Profile Identity. The first identification information is used to obtain the context of the terminal device based on the core network device.

[0203] Referring to Figure 8, the first identification information includes a profile identity, a local identifier of the first access network device (such as a Local NG-RAN Node Identifier), a second identifier of the terminal device (such as a UE specific reference), and a local identifier of the core network device (such as an AMF index). Therefore, the first identification information can be called an improved I-RNTI, which is used to identify the context of the terminal device.

[0204] For example, the Profile Identity includes K bits, where K is an integer greater than or equal to 1. Different values ​​of the K bits are used to indicate the length of the Local NG-RAN Node Identifier, the length of the UE-specific reference, and the length of the AMF index in the first identification information. Alternatively, different values ​​of the K bits are used to indicate the length of the Local NG-RAN Node Identifier and the length of the UE-specific reference in the first identification information, and the length of the AMF index is pre-configured or pre-defined.

[0205] For example, the length of the first identification information can be 40 bits, which is the same as the length of the I-RNTI. Since the first identification information introduces an AMF index relative to the I-RNTI, the length of the first identification information can be made 40 bits by adjusting the length of at least one of the Profile Identity, Local NG-RAN Node Identifier, and UE specific reference.

[0206] For example, see Table 1, K=3, the different values ​​of the 3 bits are used to indicate the length of the Local NG-RAN Node Identifier, the length of the UE specific reference, and the length of the AMF index in the first identification information.

[0207] Table 1: Examples of different values ​​for K bits

[0208] Understandably, in other examples, the different values ​​of the K bits are used to indicate the length of the Local NG-RAN Node Identifier and the length of the UE-specific reference in the first identification information, and also to indicate whether the AMF index is included, and optionally to indicate the length of the AMF index.

[0209] Implementation Method 2: The first message includes second identification information, which includes the second identifier of the terminal device and the local identifier of the first access network device. For example, the second identification information is I-RNTI.

[0210] Implementation Method 3: The first message includes first identification information and second identification information. For example, the first identification information can be called the improved I-RNTI (refer to the description in Implementation Method 1), and the second identification information is I-RNTI.

[0211] S702, the terminal device sends a second message to the second access network device, the second message being used to request the restoration of the terminal device's RRC connection; correspondingly, the second access network device receives the second message.

[0212] For example, if a terminal device determines that it needs to initiate an RRC recovery process, and if the terminal device is currently within the coverage area of ​​a second access network device, the terminal device can send a second message to the second access network device. There are several scenarios in which a terminal device determines that it needs to initiate an RRC recovery process, as described above.

[0213] (1) Regarding the above implementation method 1:

[0214] Since the first message received by the terminal device from the first access network device includes the first identification information, the terminal device can directly send an RRC recovery request message carrying the first identification information when it determines that it needs to initiate an RRC recovery process. That is, the second message (RRC recovery request message) includes the first identification information.

[0215] (2) Regarding the above implementation methods 2 and 3:

[0216] In one example, if the terminal device determines that the first access network device and the second access network device cannot communicate, it sends a second message (i.e., an RRC recovery request message) to the second access network device. This RRC recovery request message includes first identification information (such as an improved I-RNTI). If the terminal device determines that the first access network device and the second access network device can communicate (i.e., can communicate via the Xn interface), it sends another RRC recovery request message to the second access network device. This RRC recovery request message also includes second identification information (such as an I-RNTI). In other words, the terminal device can determine which identifier is specifically carried in the RRC recovery request message through the above judgment.

[0217] In another example, the second access network device can instruct the terminal device which identification information is carried in the RRC recovery request message. For instance, if the second access network device supports or can parse the improved I-RNTI, it can send a fourth piece of information to the terminal device. This fourth piece of information instructs the terminal device to report the first identification information. This fourth piece of information can be carried in a system message, message 2 (msg2) of the random access procedure, or other possible messages. Furthermore, the terminal device can send an RRC recovery request message based on this fourth piece of information, which includes the first identification information. In other words, the terminal device can determine which specific identifier is carried in the RRC recovery request message based on the received fourth piece of information.

[0218] Since the improved I-RNTI includes the content of the I-RNTI (such as the second identifier of the terminal device and the local identifier of the first access network device), if the second access network device can parse the improved I-RNTI and the second access network device and the first access network device can communicate, the context of the terminal device can be obtained based on the Xn interface according to the second identifier of the terminal device and the local identifier of the first access network device; if the second access network device and the first access network device cannot communicate, the context of the terminal device can be obtained based on the first identifier information and the core network device.

[0219] In implementation method 2, since the first message includes the second identification information but not the first identification information, when it is determined that the RRC recovery request message needs to carry the first identification information, the terminal device can obtain the first identification information based on the second identification information and the AMF index, and then send the RRC recovery request message to the second access network device. The RRC recovery request message includes the first identification information.

[0220] There are several ways for a terminal device to obtain the AMF index. One possible implementation is that the core network device sends its local identifier (i.e., the AMF index) to the terminal device.

[0221] Another possible implementation is that the second access network device sends fifth information, which indicates at least one core network device to which the second access network device is connected. For example, the fifth information includes the global identifier (such as AMF Set ID and AMF Pointer) of at least one core network device. For instance, the fifth information may include an identifier list containing the global identifiers of at least one core network device. The fifth information may be carried in a system message or other possible message. Accordingly, the terminal device receives the fifth information. The terminal device compares the AMF Set ID and AMF Pointer stored in the 5G-S-TMSI with the global identifiers of at least one core network device; for example, at least one core network device includes core network device 1, core network device 2, and core network device 3. If the global identifier of core network device 1 is the same as the AMF Set ID and AMF Pointer in the 5G-S-TMSI, the terminal device can determine the AMF index. The AMF index is the index of core network device 1 among the at least one core network device, used to characterize the order or position of the global identifier of core network device 1 in the identifier list. For example, core network device 1 has an index of 00 in at least one core network device, core network device 2 has an index of 01 in at least one core network device, and core network device 3 has an index of 10 in at least one core network device.

[0222] It is understandable that since the second access network device connects to only one core network device, and the fifth information only indicates one core network device, the aforementioned "AMF index" can be understood as an indication message. This indication message includes a bit used to indicate whether the global identifier included in the fifth information is the same as the AMF Set ID and AMF Pointer in the 5G-S-TMSI. For example, a value of 1 indicates that the global identifier included in the fifth information is the same as the AMF Set ID and AMF Pointer in the 5G-S-TMSI; a value of 0 indicates that the global identifier included in the fifth information is different from the AMF Set ID and AMF Pointer in the 5G-S-TMSI.

[0223] (3) Describe the contents that the second message may also include.

[0224] As described above, the second message includes the first identification information. Optionally, the second message also includes the global identifier of the first access network device. The global identifier of the first access network device may be independent of the first identification information, or it may be part of the first identification information.

[0225] Taking the example where the global identifier of the first access network device is independent of the first identifier information, the terminal device can obtain the global identifier of the first access network device and then send a second message. The second message includes the first identifier information and the global identifier of the first access network device. There are several ways for the terminal device to obtain the global identifier of the first access network device. One possible implementation is that the first access network device sends its global identifier to the terminal device. For example, the first access network device carries its global identifier in the suspend configuration of the first message. Another example is that the first access network device indicates the length of its global identifier in a system message (such as System Message Block 1, i.e., SIB1), and the terminal device can then extract information of the appropriate length from the global cell identifier provided in the system message or other possible messages as the global identifier of the first access network device based on the length of its global identifier.

[0226] For example, the second message is a MAC protocol data unit (PDU). If the second message also includes the global identifier of the first access network device, then part or all of the global identifier of the first access network device can be carried in the MAC subheader of the MAC PDU, and more optionally, in the logical channel ID (LCID) field of the MAC subheader. Alternatively, part or all of the global identifier of the first access network device can be carried in the resume cause field of the second message.

[0227] S703, the second access network device sends a third message to the core network device based on the second message. The third message is used to request the context of the terminal device; correspondingly, the core network device receives the third message. Here, we take an example where the second message includes first identification information (and the global identifier of the first access network device).

[0228] For example, the third message includes first identification information; or, the third message includes a second identifier of the terminal device, and a local identifier and / or a global identifier of the first access network device.

[0229] For example, since the second access network device cannot directly identify the local identifier of the core network device, the second access network device can determine the global identifier (such as AMF Set ID and AMF Pointer) of the core network device based on the local identifier of the core network device, and then send a third message to the core network device based on the global identifier of the core network device.

[0230] For example, the second access network device can obtain the first correspondence information, and then determine the global identifier of the core network device based on the local identifier of the core network device and the first correspondence information, as described in Embodiment 1. Alternatively, in the case where the local identifier of the core network device is used to indicate the index of the core network device in at least one core network device, the second access network device can directly obtain the global identifier of the core network device based on the local identifier of the core network device.

[0231] S704, the core network device sends a fourth message to the first access network device based on the third message. The fourth message is used to request the context of the terminal device. Accordingly, the first access network device receives the fourth message.

[0232] For example, the fourth message may include a second identifier of the terminal device, or the fourth message may include first identifier information.

[0233] As one possible implementation, the third message includes the global identifier of the first access network device, and the core network device can send a fourth message to the first access network device based on the global identifier of the first access network device.

[0234] As another possible implementation, the third message includes the local identifier of the first access network device, but does not include the global identifier of the first access network device. Since the core network device cannot directly identify the local identifier of the core network device, the core network device can determine the global identifier of the first access network device based on the local identifier of the first access network device, and then send the third message to the first access network device based on the global identifier of the first access network device.

[0235] The core network device can obtain the second correspondence information, which is used to indicate the correspondence between the local identifier of the first access network device and the global identifier of the first access network device. Then, the core network device can determine the global identifier of the first access network device based on the local identifier of the first access network device and the second correspondence information.

[0236] For example, access network device A sends its local identifier to the core network device. Optionally, it may also send the local identifiers and global identifiers of at least one neighboring station of access network device A. For instance, during the NG setup process, access network device A sends its local identifier, as well as the local identifiers and global identifiers of at least one neighboring station, to the core network device. Access network device A may obtain the local identifiers and global identifiers of at least one neighboring station through the Xn interface. Correspondingly, the core network device can obtain the correspondence between the local identifiers and global identifiers of access network device A, as well as the correspondence between the local identifiers and global identifiers of at least one neighboring station, based on the information reported by access network device A. The aforementioned first access network device can be access network device A, or it can be one of its neighboring stations; that is, the core network device can obtain the second correspondence information based on the information reported by the first access network device, or it can obtain the second correspondence information based on the information reported by other access network devices.

[0237] Optionally, the above method may further include some or all of the steps in S705 to S710.

[0238] S705, the first access network device sends a fifth message to the core network device according to the fourth message. The fifth message includes the second identifier of the terminal device and the context of the terminal device; correspondingly, the core network device receives the fifth message. The fifth message is a response message to the fourth message.

[0239] For example, if the fourth message includes the second identifier of the terminal device, then the fifth message here may include the second identifier of the terminal device and the context of the terminal device; if the fourth message includes the first identifier information, then the fifth message here may include the first identifier information and the context of the terminal device.

[0240] Optionally, the fifth message may also include a third identifier of the terminal device. The first access network device can obtain the third identifier based on the second identifier / first identifier information of the terminal device, and can then carry the third identifier in the fifth message.

[0241] S706, the core network device sends a sixth message to the second access network device, the sixth message including the second identifier of the terminal device and the context of the terminal device; accordingly, the second access network device receives the sixth message.

[0242] For example, if the third message includes the second identifier of the terminal device, then the sixth message here may include the second identifier of the terminal device and the context of the terminal device; if the third message includes the first identifier information, then the sixth message here may include the first identifier information and the context of the terminal device.

[0243] Optionally, if the fifth message also includes the third identifier of the terminal device, the core network device can establish a correspondence between the second identifier (or first identifier information) and the third identifier of the terminal device based on the fifth message.

[0244] S707, the second access network device sends an RRC recovery message to the terminal device; correspondingly, the terminal device receives the RRC recovery message and restores the RRC connection.

[0245] For example, after obtaining the context of the terminal device, if the second access network device determines to restore the RRC connection of the terminal device, it sends an RRC restoration message to the terminal device. In other examples, the second access network device may choose not to restore the RRC connection of the terminal device.

[0246] S708, the terminal device sends a seventh message (such as an RRC recovery completion message) to the second access network device to indicate that the RRC connection of the terminal device has been restored; correspondingly, the second access network device receives the RRC recovery completion message.

[0247] S709, the second access network device sends an eighth message to the core network device according to the seventh message. The eighth message includes the second identifier or the first identifier information of the terminal device. The eighth message is used to indicate the deletion of the context of the terminal device stored by the first access network device. Accordingly, the core network device receives the eighth message.

[0248] S710, the core network device sends a ninth message to the first access network device according to the eighth message. The ninth message is used to instruct the first access network device to delete the context of the terminal device stored therein. Accordingly, the first access network device receives the ninth message and deletes the context of the terminal device according to the ninth message.

[0249] For example, if the fifth message includes the third identifier of the terminal device, after receiving the eighth message, the core network device can determine the third identifier based on the correspondence between the second identifier (or first identifier information) and the third identifier of the terminal device, and send a ninth message to the first access network device, the ninth message including the third identifier. Accordingly, the first access network device can determine the corresponding second identifier or first identifier information based on the third identifier in the ninth message, and then delete the context of the terminal device based on the second identifier or first identifier information.

[0250] If the fifth message does not include the third identifier of the terminal device, then the ninth message includes the second identifier or the first identifier information of the terminal device. Accordingly, the first access network device can delete the context of the terminal device based on the second identifier or the first identifier information of the terminal device.

[0251] The above steps use the example of "the core network device sending a ninth message to the first access network device based on the eighth message sent by the second access network device." In other examples, the core network device may also send a ninth message to the first access network device after determining that the timer has expired. The ninth message includes the second or first identifier information of the terminal device, or the ninth message includes the third identifier of the terminal device. The start time of the timer can be the time of receiving the third message, the time of sending the fourth message, the time of receiving the fifth message, or the time of sending the sixth message. The duration of the timer can be pre-configured or predefined, and is not specifically limited.

[0252] Using the above method, a new first identification information (such as an improved I-RNTI) is introduced. The terminal device carries the first identification information in the RRC recovery request message. This allows the second access network device to obtain the context of the terminal device based on the core network device. Therefore, even when communication between the first and second access network devices is impossible, the second access network device can still obtain the context of the terminal device. Specifically, the first identification information includes a second identifier assigned to the terminal device by the first access network device, a local identifier / global identifier of the first access network device, and a local identifier of the core network device. The second access network device can locate the corresponding core network device based on the local identifier of the core network device and send a third message. The core network device can locate the corresponding anchor access network device based on the local identifier / global identifier of the first access network device and send a fourth message to obtain the context of the terminal device.

[0253] Example 3

[0254] Figure 9 is a flowchart illustrating the communication method provided in Embodiment 3 of this application. As shown in Figure 9, the process may include:

[0255] S901, the first access network device sends a first message to the terminal device, the first message being used to instruct the terminal device to enter the inactive state; accordingly, the terminal device receives the first message and enters the inactive state.

[0256] Here, the first access network device is the anchor access network device of the terminal device. After the terminal device enters the inactive state, the first access network device still stores the context of the terminal device. For example, the first message is an RRC release message, and the first message includes second identification information (such as I-RNTI).

[0257] S902, the terminal device sends a second message to the second access network device, the second message being used to request the restoration of the terminal device's RRC connection; correspondingly, the second access network device receives the second message.

[0258] For example, if the terminal device determines that it needs to initiate an RRC recovery process, and if the terminal device is currently within the coverage area of ​​the second access network device, the terminal device can send a second message to the second access network device.

[0259] In one example, if the terminal device determines that the first access network device and the second access network device cannot communicate, it sends a second message (i.e., an RRC recovery request message) to the second access network device. The RRC recovery request message includes first identification information, which includes second identification information and the local identifier of the core network device. Optionally, it also includes the global identifier of the first access network device. If the terminal device determines that the first access network device and the second access network device can communicate, it sends an RRC recovery request message to the second access network device, which includes the second identification information. In other words, the terminal device can determine which identifier is specifically carried in the RRC recovery request message through the above judgment.

[0260] In another example, the second access network device can instruct the terminal device which specific identification information the RRC recovery request message carries. For instance, the second access network device can send a fourth message to the terminal device. This fourth message instructs the terminal device to report the first identification information, or in other words, it instructs the terminal device to report the local identifier of the core network device (and the global identifier of the first access network device). This fourth message can be carried in a system message, message 2 (msg2) of the random access procedure, or other possible messages. Furthermore, the terminal device can send an RRC recovery request message based on this fourth message, which includes the first identification information. In other words, the terminal device can determine which specific identifier the RRC recovery request message carries based on the received fourth message.

[0261] The specific implementation of the terminal device obtaining the local identifier of the core network device and the global identifier of the first access network device can be referred to the description in Embodiment 2.

[0262] For example, if the second message is a MAC PDU, and the second message includes second identification information and the local identifier of the core network device, part or all of the local identifier of the core network device may be carried in the MAC subheader of the MAC PDU, and more optionally, in the LCID field of the MAC subheader; or, part or all of the local identifier of the core network device may be carried in the resume cause field of the second message. If the second message also includes the global identifier of the first access network device, then part or all of the global identifier of the first access network device may be carried in the LCID field of the MAC subheader, or in the resume cause field.

[0263] S903, the second access network device sends a third message to the core network device based on the second message. The third message is used to request the context of the terminal device; correspondingly, the core network device receives the third message. Here, the second message includes the first identification information as an example.

[0264] For example, the third message includes second identification information; or, the third message includes the second identifier of the terminal device, and the local identifier and / or the global identifier of the first access network device.

[0265] For example, since the second access network device cannot directly identify the local identifier of the core network device, the second access network device can determine the global identifier (such as AMF Set ID and AMF Pointer) of the core network device based on the local identifier of the core network device, and then send a third message to the core network device based on the global identifier of the core network device.

[0266] S904, the core network device sends a fourth message to the first access network device based on the third message. The fourth message is used to request the context of the terminal device. Accordingly, the first access network device receives the fourth message.

[0267] For example, the fourth message includes a second identifier of the terminal device, or the fourth message includes second identifier information. The specific implementation of S904 can refer to S704.

[0268] Optionally, the above method may further include some or all of the steps in S905 to S910.

[0269] S905, the first access network device sends a fifth message to the core network device according to the fourth message. The fifth message includes the second identifier of the terminal device and the context of the terminal device; correspondingly, the core network device receives the fifth message. The fifth message is a response message to the fourth message.

[0270] For example, if the fourth message includes the second identifier of the terminal device, then the fifth message here may include the second identifier of the terminal device and the context of the terminal device; if the fourth message includes the second identifier information, then the fifth message here may include the second identifier information and the context of the terminal device.

[0271] Optionally, the fifth message may also include a third identifier of the terminal device. The first access network device can obtain the third identifier based on the second identifier / second identifier information of the terminal device, and can then carry the third identifier in the fifth message.

[0272] S906, the core network device sends a sixth message to the second access network device. The sixth message includes the second identifier of the terminal device and the context of the terminal device; accordingly, the second access network device receives the sixth message.

[0273] For example, if the third message includes the second identifier of the terminal device, then the sixth message here may include the second identifier of the terminal device and the context of the terminal device; if the third message includes the second identifier information, then the sixth message here may include the second identifier information and the context of the terminal device.

[0274] Optionally, if the fifth message also includes the third identifier of the terminal device, the core network device can establish a correspondence between the second identifier (or second identifier information) and the third identifier of the terminal device based on the fifth message.

[0275] S907, the second access network device sends an RRC recovery message to the terminal device; correspondingly, the terminal device receives the RRC recovery message and restores the RRC connection.

[0276] For example, after obtaining the context of the terminal device, if the second access network device determines to restore the RRC connection of the terminal device, it sends an RRC restoration message to the terminal device. In other examples, the second access network device may choose not to restore the RRC connection of the terminal device.

[0277] S908, the terminal device sends a seventh message (such as an RRC recovery completion message) to the second access network device to indicate that the RRC connection of the terminal device has been restored; correspondingly, the second access network device receives the RRC recovery completion message.

[0278] S909, the second access network device sends an eighth message to the core network device according to the seventh message. The eighth message includes the second identifier or second identifier information of the terminal device. The eighth message is used to indicate the deletion of the context of the terminal device stored by the first access network device. Accordingly, the core network device receives the eighth message.

[0279] S910, the core network device sends a ninth message to the first access network device according to the eighth message. The ninth message is used to instruct the first access network device to delete the context of the terminal device stored therein. Accordingly, the first access network device receives the ninth message and deletes the context of the terminal device according to the ninth message.

[0280] For example, if the fifth message includes the third identifier of the terminal device, after receiving the eighth message, the core network device can determine the third identifier based on the correspondence between the second identifier (or second identifier information) and the third identifier of the terminal device, and send a ninth message to the first access network device, wherein the ninth message includes the third identifier. Accordingly, the first access network device can determine the corresponding second identifier or second identifier information based on the third identifier in the ninth message, and then delete the context of the terminal device based on the second identifier or second identifier information.

[0281] If the fifth message does not include the third identifier of the terminal device, then the ninth message includes the second identifier or second identifier information of the terminal device. Accordingly, the first access network device can delete the context of the terminal device based on the second identifier or second identifier information of the terminal device.

[0282] The above steps use the example of "the core network device sending a ninth message to the first access network device based on the eighth message sent by the second access network device." In other examples, the core network device may also send a ninth message to the first access network device after determining that the timer has expired. The ninth message includes the second identifier or second identifier information of the terminal device, or the ninth message includes the third identifier of the terminal device. The start time of the timer can be the time of receiving the third message, the time of sending the fourth message, the time of receiving the fifth message, or the time of sending the sixth message. The duration of the timer can be pre-configured or predefined, and is not specifically limited.

[0283] Using the above method, new first identification information is introduced, including the I-RNTI and the local identifier of the core network device (and the global identifier of the first access network device). This allows the second access network device to obtain the context of the terminal device based on the core network device, ensuring that the second access network device can still obtain the terminal device's context even when communication between the first and second access network devices is impossible. Specifically, the second access network device can locate the corresponding core network device based on the core network device's local identifier and send a third message; the core network device can locate the corresponding anchor access network device based on the first access network device's local / global identifier and send a fourth message to obtain the terminal device's context.

[0284] Regarding the above embodiments, it is understood that:

[0285] (1) The above embodiments are described using the access network device as a whole as an example. In other embodiments, the access network device may include a DU and a CU that manages the DU. In this case, the terminal device can communicate with the CU through the DU. For example, the terminal device sends a second message to the DU, and the DU can parse the second message to obtain the RRC recovery request encapsulated by the RRC layer (for example, in Embodiment 1 or Embodiment 2, the RRC recovery request includes the first identification information), and forward the RRC recovery request to the CU. Then, the CU sends a third message to the core network device according to the first identification information in the RRC recovery request. Alternatively, the terminal device sends a second message to the DU, and the DU can parse the second message to obtain the local identifier of the core network device and the RRC recovery request encapsulated by the RRC layer carried in the MAC subheading (for example, in Embodiment 3, the RRC recovery request includes the second identification information), and send the local identifier of the core network device and the RRC recovery request to the CU. Then, the CU sends a third message to the core network device according to the local identifier of the core network device. The specific implementation process will not be described in detail.

[0286] (2) In the various embodiments of this application, unless otherwise specified or logically conflicting, the terminology and / or descriptions between different embodiments are consistent and can be referenced by each other. Technical features in different embodiments can be combined to form new embodiments based on their inherent logical relationships. Furthermore, in the same embodiment, different implementations or different examples can also be referenced or referenced by each other.

[0287] (3) The various numerical designations used in this application are merely for descriptive convenience and are not intended to limit the scope of this application. The step numbers in the above flowcharts are only examples of the execution process and do not constitute a restriction on the order of execution of the steps. That is, the size of each step number does not imply the order of execution, and the execution order of each step should be determined by its function and internal logic. In addition, not all steps shown in the flowcharts are mandatory steps, and some steps can be added or deleted based on actual needs.

[0288] The foregoing mainly describes the solutions provided by the embodiments of this application from the perspective of interaction among multiple communication devices. It is understood that, in order to achieve the above functions, the multiple communication devices may include hardware structures and / or software modules corresponding to the execution of each function. Those skilled in the art should readily recognize that, in conjunction with the units and algorithm steps of the various examples described in the embodiments disclosed herein, the embodiments of this application can be implemented in hardware or a combination of hardware and computer software. Whether a function is executed in hardware or by computer software driving hardware depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0289] This application embodiment can divide multiple communication devices (such as a first communication device, a second communication device, and a third communication device) into functional units according to the above method example. For example, each function can be divided into a separate functional unit, or two or more functions can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0290] In the case of using integrated units, FIG10 shows a possible exemplary block diagram of the device involved in the embodiments of this application. As shown in FIG10, the device 1000 may include a processing unit 1002 and a communication unit 1003. The processing unit 1002 is used to control and manage the operation of the device 1000. The communication unit 1003 is used to support communication between the device 1000 and other devices. Optionally, the communication unit 1003 is also called a transceiver unit, and may include a receiving unit and / or a sending unit, respectively used to perform receiving and sending operations. The device 1000 may also include a storage unit 1001 for storing the program code and / or data of the device 1000.

[0291] (1) The device 1000 may be the first communication device in the above embodiments. The processing unit 1002 may support the device 1000 in performing the actions of the first communication device in the above method embodiments. Alternatively, the processing unit 1002 may mainly perform the internal actions of the first communication device in the method embodiments, and the communication unit 1003 may support communication between the device 1000 and other devices.

[0292] For example, in one embodiment, the communication unit 1003 is configured to: receive a first message from a first access network device, the first message being used to instruct the terminal device to enter an inactive state; send a second message to a second access network device, the second message being used to request the restoration of the RRC connection of the terminal device, the second message including first identification information, the first identification information including the identifier of the terminal device and the identifier of the core network device; wherein, the first identification information is used to obtain the context of the terminal device based on the core network device.

[0293] Other further technical features can be found in the descriptions in the above method embodiments.

[0294] (2) The device 1000 can be the second communication device in the above embodiments. The processing unit 1002 can support the device 1000 in performing the actions of the second communication device in the above method embodiments. Alternatively, the processing unit 1002 mainly performs the internal actions of the second communication device in the method embodiments, and the communication unit 1003 can support communication between the device 1000 and other devices.

[0295] For example, in one embodiment, the communication unit 1003 is configured to: receive a second message from a terminal device, the second message being used to request the restoration of the RRC connection of the terminal device, the second message including first identification information, the first identification information including the identifier of the terminal device and the identifier of the core network device; and send a third message to the core network device according to the identifier of the core network device, the third message including the identifier of the terminal device, the third message being used to request the acquisition of the context of the terminal device.

[0296] Other further technical features can be found in the descriptions in the above method embodiments.

[0297] (3) The device 1000 can be the third communication device in the above embodiments. The processing unit 1002 can support the device 1000 in performing the actions of the third communication device in the above method embodiments. Alternatively, the processing unit 1002 mainly performs the internal actions of the third communication device in the method embodiments, and the communication unit 1003 can support communication between the device 1000 and other devices.

[0298] For example, in one embodiment, the communication unit 1003 is configured to: receive a third message from a second access network device, the third message including the identifier of the terminal device, the third message being used to request the context of the terminal device; and send a fourth message to a first access network device according to the third message, the fourth message being used to request the context of the terminal device, the first access network device storing the context of the terminal device.

[0299] Other further technical features can be found in the descriptions in the above method embodiments.

[0300] It should be understood that the division of units in the above device is merely a logical functional division. In actual implementation, they can be fully or partially integrated into a single physical entity, or they can be physically separated. Furthermore, all units in the device can be implemented entirely through software calls from processing elements; all units can be implemented entirely in hardware; or some units can be implemented through software calls from processing elements, while others are implemented in hardware. For example, each unit can be a separate processing element, or it can be integrated into a chip within the device. Alternatively, it can be stored as a program in memory, called and executed by a processing element of the device. Moreover, these units can be fully or partially integrated together, or implemented independently. The processing element here can also be called a processor, which can be an integrated circuit with signal processing capabilities. In the implementation process, the operations or units described above can be implemented through integrated logic circuits in the processor element or through software calls from processing elements.

[0301] In one example, a unit in any of the above devices can be one or more integrated circuits configured to implement the methods described above, such as one or more application-specific integrated circuits (ASICs), or one or more digital signal processors (DSPs), or one or more field-programmable gate arrays (FPGAs), or a combination of at least two of these forms of integrated circuits. As another example, when a unit in the device can be implemented in the form of a processing element scheduler, the processing element can be a processor, such as a central processing unit (CPU), or other processor capable of calling programs. Furthermore, these units can be integrated together to implement a system-on-chip (SoC).

[0302] The receiving unit described above is an interface circuit of the device, used to receive signals from other devices. For example, when the device is implemented as a chip, the receiving unit is an interface circuit for the chip to receive signals from other chips or devices. The transmitting unit described above is an interface circuit of the device, used to transmit signals to other devices. For example, when the device is implemented as a chip, the transmitting unit is an interface circuit for the chip to transmit signals to other chips or devices.

[0303] Based on the above embodiments, this application also provides a communication device. Referring to FIG11, the communication device 1100 may include one or more processors 1101. Optionally, the communication device 1100 may further include a memory 1102, which may be disposed inside or outside the communication device 1100. It is understood that FIG11 only shows the main components of the communication device, and the communication device may further include a transceiver (not shown in the figure).

[0304] Specifically, processor 1101 can be a CPU, a network processor (NP), or a combination of a CPU and an NP. Processor 1101 may further include a hardware chip. The aforementioned hardware chip can be an ASIC, a programmable logic device (PLD), or a combination thereof. The aforementioned PLD can be a complex programmable logic device (CPLD), an FPGA, generic array logic (GAL), or any combination thereof.

[0305] The processor 1101 and memory 1102 are interconnected. Optionally, the processor 1101 and memory 1102 are interconnected via bus 1103; bus 1103 can be a peripheral component interconnect (PCI) bus or an extended industry standard architecture (EISA) bus, etc. Buses can be categorized as address buses, data buses, control buses, etc. For ease of illustration, only one thick line is used in Figure 11, but this does not indicate that there is only one bus or one type of bus.

[0306] In one alternative implementation, memory 1102 is used to store programs, etc. Specifically, the program may include program code, which includes computer operation instructions. Memory 1102 may include RAM, and may also include non-volatile memory, such as one or more disk storage devices. Processor 1101 executes the application program stored in memory 1102 to implement the above-mentioned functions, thereby realizing the functions of communication device 1100.

[0307] For example, the communication device 1100 may be the first communication device, the second communication device, or the third communication device in the above embodiments.

[0308] In one embodiment, when the communication device 1100 performs the functions of the first communication device in the above method embodiment, the transceiver can perform the transmit and receive operations executed by the first communication device in the above method embodiment; the processor 1101 can perform other operations besides the transmit and receive operations executed by the first communication device in the above method embodiment. Specific details can be found in the relevant descriptions in the above embodiments, and will not be elaborated upon here.

[0309] In one embodiment, when the communication device 1100 performs the functions of the second communication device in the above method embodiment, the transceiver can perform the transmit and receive operations executed by the second communication device in the above method embodiment; the processor 1101 can perform other operations besides the transmit and receive operations executed by the second communication device in the above method embodiment. Specific details can be found in the relevant descriptions in the above embodiments, and will not be elaborated upon here.

[0310] In one embodiment, when the communication device 1100 performs the functions of the third communication device in the above method embodiment, the transceiver can perform the transmit and receive operations executed by the third communication device in the above method embodiment; the processor 1101 can perform other operations besides the transmit and receive operations executed by the third communication device in the above method embodiment. Specific details can be found in the relevant descriptions in the above embodiments, and will not be elaborated upon here.

[0311] The terms "system" and "network" in this application embodiment are used interchangeably. "At least one" refers to one or more, and "multiple" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one of A, B, and C" includes A, B, C, AB, AC, BC, or ABC. And, unless otherwise specified, the ordinal numbers such as "first" and "second" mentioned in this application embodiment are used to distinguish multiple objects and are not used to limit the order, sequence, priority, or importance of multiple objects.

[0312] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0313] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to this application. It should be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in one or more blocks of the flowchart illustrations and / or one or more blocks of the block diagrams.

[0314] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means that implement the functions specified in one or more flowcharts and / or one or more block diagrams.

[0315] These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process, such that the instructions, which execute on the computer or other programmable apparatus, provide steps for implementing the functions specified in one or more flowcharts and / or one or more block diagrams.

Claims

1. A communication method, characterized in that, The method is applied to a terminal device or a chip in the terminal device, and the method includes: Receive a first message from a first access network device, the first message being used to instruct the terminal device to enter an inactive state; Send a second message to the second access network device. The second message is used to request the restoration of the Radio Resource Control (RRC) connection of the terminal device. The second message includes first identification information, which includes the identifier of the terminal device and the identifier of the core network device. The first identification information is used to obtain the context of the terminal device based on the core network device.

2. The method according to claim 1, characterized in that, The method further includes: It was determined that the first access network device and the second access network device could not communicate.

3. The method according to claim 2, characterized in that, Determining that the first access network device and the second access network device cannot communicate includes: Receive first information from the first access network device, the first information indicating a first area; if the terminal device is located in the first area, determine that the first access network device and the second access network device cannot communicate; or, The system receives second information from the first access network device, the second information indicating M access network devices capable of communicating with the first access network device, where M is an integer greater than or equal to 1; if the second access network device is not among the M access network devices, it is determined that the first access network device and the second access network device cannot communicate; or... The system receives third information from the second access network device, which indicates N access network devices that can communicate with the second access network device, where N is an integer greater than or equal to 1; if the first access network device is not among the N access network devices, it is determined that the first access network device and the second access network device cannot communicate.

4. The method according to claim 1, characterized in that, The method further includes: The terminal device receives fourth information from the second access network device, the fourth information being used to instruct the terminal device to report the first identification information.

5. The method according to any one of claims 1 to 3, characterized in that, The identifier of the terminal device is the first identifier assigned to the terminal device by the core network device.

6. The method according to claim 5, characterized in that, The method further includes: Receive the first identification information from the core network device.

7. The method according to any one of claims 1 to 4, characterized in that, The identifier of the terminal device is a second identifier assigned to the terminal device by the first access network device, and the first identifier information also includes the identifier of the first access network device.

8. The method according to claim 7, characterized in that, The method further includes: Receive the first identification information from the first access network device.

9. The method according to claim 7, characterized in that, The method further includes: The terminal device receives second identification information from the first access network device. The second identification information includes the identifier of the terminal device and the identifier of the first access network device. The second identification information is used to obtain the context of the terminal device based on the communication interface between the first access network device and the second access network device. The first identification information is obtained based on the second identification information and the identification of the core network device.

10. The method according to claim 9, characterized in that, The method further includes: The device receives fifth information from the second access network device, the fifth information being used to indicate at least one core network device connected to the second access network device, the at least one core network device including the core network device; Based on the fifth piece of information, the identifier of the core network device is determined, and the identifier of the core network device is the index of the core network device in the at least one core network device.

11. The method according to any one of claims 1 to 10, characterized in that, The method further includes: A sixth message is sent to the second access network device, the sixth message indicating that the first identification information includes the identifier of the terminal device and the identifier of the core network device.

12. A communication method, characterized in that, The method is applied to a second access network device or a chip in the second access network device, and the method includes: A second message is received from the terminal device, the second message being used to request the restoration of the RRC connection of the terminal device, the second message including first identification information, the first identification information including the identifier of the terminal device and the identifier of the core network device; Based on the identifier of the core network device, a third message is sent to the core network device. The third message includes the identifier of the terminal device and is used to request the context of the terminal device.

13. The method according to claim 12, characterized in that, The identifier of the terminal device is a first identifier assigned to the terminal device by the core network device; or... The identifier of the terminal device is a second identifier assigned to the terminal device by the first access network device, and the third message also includes the identifier of the first access network device.

14. The method according to claim 12 or 13, characterized in that, The identifier of the core network device is the local identifier of the core network device; Based on the identifier of the core network device, a third message is sent to the core network device, including: The global identifier of the core network device is determined based on the local identifier of the core network device; The third message is sent to the core network device based on the global identifier of the core network device.

15. The method according to claim 14, characterized in that, Based on the local identifier of the core network device, the global identifier of the core network device is determined, including: Obtain first correspondence information, which is used to indicate the correspondence between the local identifier of the core network device and the global identifier of the core network device; The global identifier of the core network device is determined based on the local identifier of the core network device and the first correspondence information.

16. The method according to claim 14, characterized in that, The method further includes: Send a fifth message, the fifth message including a global identifier of at least one core network device connected to the second access network device, the at least one core network device including the core network device; The local identifier of the core network device is the index of the core network device in the at least one core network device.

17. A communication method, characterized in that, The method is applied to a core network device or a chip in the core network device, and the method includes: Receive a third message from a second access network device, the third message including the identifier of the terminal device, the third message being used to request the context of the terminal device; According to the third message, a fourth message is sent to the first access network device. The fourth message is used to request the context of the terminal device, and the first access network device stores the context of the terminal device.

18. The method according to claim 17, characterized in that, The identifier of the terminal device is the first identifier assigned to the terminal device by the core network device.

19. The method according to claim 18, characterized in that, Based on the third message, a fourth message is sent to the first access network device, including: Based on the first identifier, the third identifier of the terminal device and the first access network device are determined; The fourth message is sent to the first access network device, the fourth message including the third identifier.

20. The method according to claim 19, characterized in that, The method further includes: Receive a fifth message from the first access network device, the fifth message including the third identifier and the context of the terminal device; A sixth message is sent to the second access network device, the sixth message including the first identifier and the context of the terminal device.

21. The method according to claim 17, characterized in that, The identifier of the terminal device is a second identifier assigned to the terminal device by the first access network device, and the third message also includes the identifier of the first access network device.

22. The method according to claim 21, characterized in that, The identifier of the first access network device is the local identifier of the first access network device; Based on the third message, a fourth message is sent to the first access network device, including: The global identifier of the first access network device is determined based on the local identifier of the first access network device. The fourth message is sent to the first access network device based on the global identifier of the first access network device.

23. The method according to claim 22, characterized in that, Based on the local identifier of the first access network device, determine the global identifier of the first access network device, including: Obtain second correspondence information, which is used to indicate the correspondence between the local identifier of the first access network device and the global identifier of the first access network device; The global identifier of the first access network device is determined based on the local identifier of the first access network device and the second correspondence information.

24. The method according to claim 21, characterized in that, The identifier of the first access network device is the global identifier of the first access network device; Based on the third message, a fourth message is sent to the first access network device, including: The fourth message is sent to the first access network device based on the global identifier of the first access network device.

25. The method according to any one of claims 21 to 24, characterized in that, The fourth message includes the second identifier.

26. The method according to any one of claims 21 to 25, characterized in that, The method further includes: Receive a fifth message from the first access network device, the fifth message including the second identifier and the context of the terminal device; A sixth message is sent to the second access network device, the sixth message including the second identifier and the context of the terminal device.

27. A communication device, characterized in that, The device includes a processor coupled to a memory in which a computer program is stored; the processor is configured to invoke part or all of the computer program in the memory such that the method as described in any one of claims 1 to 26 is executed.

28. A communication system, characterized in that, The communication system includes a first communication device, a second communication device, and a third communication device, wherein the first communication device is used to perform the method as described in any one of claims 1 to 11, the second communication device is used to perform the method as described in any one of claims 12 to 16, and the third communication device is used to perform the method as described in any one of claims 17 to 26.

29. A computer-readable storage medium, characterized in that, The storage medium stores a computer program that, when some or all of the computer program is executed by a computer, causes the method described in any one of claims 1 to 26 to be performed.

30. A computer program product, characterized in that, When the computer reads and executes the computer program product, the method described in any one of claims 1 to 26 is performed.

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