Information transmission method and communication device

Abstract

The embodiment of the invention provides an information transmission method and a communication device, which can ensure that session management can be reliably carried out in a terminal switching process under the condition of decoupling session-related functions of an access mobility management network element. The method comprises the following steps: in the process of switching a service radio access network of a first terminal from a source radio access network to a target radio access network RAN, the target radio access network acquires service area information corresponding to the first terminal from the source radio access network; the target wireless access network determines first indication information according to the position information of the first terminal and the service area information, the first indication information being used for indicating whether the first terminal is located in a service area indicated by the service area information; and the target wireless access network sends the first indication information to a session management network element, wherein the session management network element is used for managing the session of the first terminal.

Description

Technical Field

[0001] This application relates to the field of communications, and in particular to information transmission methods and communication devices. Background Technology

[0002] In research on future communication networks, decoupling the access and mobility management function (AMF) from session-related functions can improve the flexibility of communication networks and better meet the needs of new services.

[0003] However, how to ensure reliable session management during handover while decoupling AMF's session-related functions is currently a hot research topic. Summary of the Invention

[0004] The information transmission method and communication device provided in this application embodiment can ensure reliable session management during terminal handover while decoupling AMF session-related functions.

[0005] To achieve the above objectives, the embodiments of this application adopt the following technical solutions:

[0006] In a first aspect, an information transmission method is provided, the method comprising: during the process of a first terminal's serving RAN switching from a source RAN to a target radio access network RAN, the target RAN obtains service area information corresponding to the first terminal from the source RAN; the target RAN determines first indication information based on the location information and service area information of the first terminal, the first indication information being used to indicate whether the first terminal is located in the service area indicated by the service area information; and the target RAN sends the first indication information to a session management network element, the session management network element being used to manage the session of the first terminal.

[0007] In this embodiment, the target RAN, by obtaining the service area information corresponding to the first terminal, can determine whether the first terminal is located within the service area indicated by the service area information based on the location information of the first terminal and the service area information. Then, it instructs the session management network element (SMI) through the first indication information. This allows the SMI to determine which sessions of the first terminal need to be switched, or whether sessions need to be deactivated or released. Therefore, the information transmission method provided in this embodiment can reliably manage sessions during the handover process while decoupling the session-related functions of the AMF.

[0008] Furthermore, since the target RAN determines whether the first terminal is located in the service area indicated by the service area information corresponding to the first terminal, after the target RAN sends handover signaling to the access mobility management network element, it does not need to send handover signaling to the session management network element based on the information fed back by the access mobility management network element regarding whether the first terminal is located in the service area. Therefore, the handover signaling sent by the target RAN to the session management network element and the access mobility management network element respectively has no timing requirements, which can better decouple the functions of the access mobility network element and the session management network element and further enhance flexibility.

[0009] In one possible implementation, the target RAN sends the first indication information to the session management network element (SMN) through its interface with the SMN. In other words, by sending the first indication information through the interface, the target RAN can decouple session-related functions from the access mobility management network element, thereby improving flexibility.

[0010] In one possible implementation, the service area information includes the service area restriction SAR information of the first terminal, and / or the service area information of the data network corresponding to the session of the first terminal. That is, the target RAN can obtain the SAR information of the first terminal, and / or the service area information of the data network corresponding to the session of the first terminal, and thus determine whether the first terminal is located in the permitted area indicated by the SAR information, and / or whether the first terminal is located in the service area indicated by the LADN information of the data network corresponding to the session of the first terminal.

[0011] In one possible implementation, the first indication information is used to indicate whether the first terminal is located within the permitted area indicated by the SAR information of the first terminal, and / or whether the first terminal is located within the service area indicated by the service area information of the data network corresponding to the first terminal's session. That is, by indicating to the session management network element whether the first terminal is located within the permitted area indicated by the SAR information of the first terminal, the target RAN can enable the session management network element to determine whether to activate or release all non-urgent service sessions of the first terminal based on whether the first terminal is located within the permitted area. Furthermore, by indicating to the session management network element corresponding to the i-th session among the multiple sessions of the first terminal whether the first terminal is located within the service area indicated by the service area information (e.g., LADN information) of the data network corresponding to the i-th session, the target RAN can enable the session management network element to determine whether to activate or release the i-th session based on whether the first terminal is located within the service area.

[0012] In one possible implementation, the target RAN sends a first indication message to the session management network element, including: the target RAN sending the first indication message to the session management network element based on the fact that the first terminal is not in the permitted area indicated by the SAR information of the first terminal. The first indication message is used to indicate that the first terminal is not in the permitted area. That is, the target RAN can send the first indication message to the session management network element based on the fact that the first terminal is not in the permitted area indicated by the SAR information of the first terminal to indicate that the first terminal is not in the permitted area. This allows the session management network element to determine that the establishment of a non-urgent service session for the first terminal is not allowed. Thus, while decoupling the session-related functions in the access mobility management network element, reliable session management can be further guaranteed during the handover process.

[0013] In one possible implementation, the target RAN sends a first indication message to the session management network element, including: the target RAN sending a first request to the session management network element, the first request being used to request the activation or release of the first terminal's session, the first request including the first indication message. That is, by requesting the session management network element to activate or release the first terminal's session, the target RAN can implicitly indicate that the first terminal is not within the permitted area indicated by the SAR information, thereby enabling the session management network element to activate or release the first terminal's session according to the request.

[0014] In one possible implementation, the session of the first terminal corresponds to a non-urgent service. The target RAN sends a first request to the session management network element, including: the target RAN sending the first request to the session management network element based on the fact that the session of the first terminal corresponds to a non-urgent service. That is, the target RAN can request the session management network element to activate or release the session corresponding to the non-urgent service of the first terminal, implicitly indicating that the first terminal is not in the permitted area indicated by the SAR information. This allows the session management network element to activate or release the session corresponding to the non-urgent service of the first terminal according to the request, avoiding the activation or release of the session corresponding to the urgent service of the first terminal. Thus, while decoupling the session-related functions in the access mobility management network element, reliable session management can be further guaranteed during handover.

[0015] In one possible implementation, the first request includes a first reason value, which indicates that the reason for sending the first request is that the first terminal is not in the permitted area indicated by the SAR information of the first terminal. That is, by indicating through the first reason value that the reason for activating or releasing the first terminal's session is that the first terminal is not in the permitted area indicated by the SAR information of the first terminal, the session management network element can avoid attempting to re-establish the first terminal's session after deactivating or releasing it. This further ensures reliable session management during handover, even when the session-related functions in the access mobility management network element are decoupled.

[0016] In one possible implementation, the method provided by the first aspect further includes: the target RAN receiving second indication information from the first terminal, the second indication information indicating that the air interface handover is complete; and the target RAN sending third indication information to the access mobility management network element based on the fact that the first terminal is located within the permitted area indicated by the SAR information of the first terminal. The third indication information is used to instruct the serving RAN of the first terminal to switch from the source RAN to the target RAN. In other words, the target RAN can send a handover-related indication (i.e., the third indication) to the access mobility management network element based on the fact that the first terminal is located within the permitted area indicated by the SAR information, thereby notifying the access mobility management network element that the serving RAN of the first terminal is switching from the source RAN to the target RAN. This allows the target RAN to send handover-related indications to both the session management network element and the access mobility management network element, achieving functional decoupling between the SMF and AMF and enhancing flexibility.

[0017] In one possible implementation, the target RAN sends a first indication message to the session management network element, including: the target RAN sending a second request to the session management network element, the second request requesting a switch of the serving RAN of the first terminal from the source RAN to the target RAN, the second request including the first indication message. That is, the target RAN can send a second request including the first indication message to the session management network element based on whether the first terminal is located in the permitted area indicated by the SAR information. Then, the session management network element can perform session switching, session deactivation, or release of the first terminal's session based on whether the first terminal is located in the permitted area indicated by the SAR information, and / or whether the first terminal is located in the service area indicated by the service area information of the data network corresponding to the first terminal's session.

[0018] Secondly, an information transmission method is provided, the method comprising: a source radio access network (RAN) acquiring service area information corresponding to a first terminal; during the process of the first terminal's service RAN switching from the source RAN to the target RAN, the source RAN determining first indication information based on the location information and service area information of the first terminal, the first indication information being used to indicate whether the first terminal is located in the service area indicated by the service area information; and the source RAN sending the first indication information to a session management network element, the session management network element being used to manage the session of the first terminal.

[0019] In one possible implementation, the source RAN specifically sends the first instruction information to the session management network element through the interface between the source RAN and the session management network element.

[0020] In one possible implementation, the service area information includes the service area restriction SAR information of the first terminal, and / or the service area information of the data network corresponding to the session of the first terminal.

[0021] In one possible implementation, the first indication information is used to indicate whether the first terminal is located in the permitted area indicated by the SAR information of the first terminal, and / or whether the first terminal is located in the service area indicated by the service area information of the data network corresponding to the session of the first terminal.

[0022] In one possible implementation, the source RAN sends a first indication message to the session management network element, including: the source RAN sends the first indication message to the session management network element based on the fact that the first terminal is not in the allowed area indicated by the SAR information of the first terminal, and the first indication message is used to indicate that the first terminal is not in the allowed area.

[0023] In one possible implementation, the source RAN sends a first indication message to the session management network element, including: the source RAN sends a third request to the session management network element, the third request being used to request deactivation or release of the session of the first terminal, the third request including the first indication message.

[0024] In one possible implementation, the session of the first terminal is a session corresponding to a non-urgent service; the source RAN sends a third request to the session management network element, including: the source RAN sending a third request to the session management network element based on the fact that the session of the first terminal is a session corresponding to a non-urgent service.

[0025] In one possible implementation, the third request includes a second cause value, which indicates that the reason for sending the third request is that the first terminal is not in the permitted area indicated by the SAR information of the first terminal.

[0026] In one possible implementation, the source RAN sends a first indication message to the session management network element, including: the source RAN sending a fourth request to the session management network element, the fourth request being used to request preparation to switch the serving RAN of the first terminal from the source RAN to the target RAN, the fourth request including the first indication message.

[0027] The beneficial effects of the second aspect and any of its implementations can be found in the beneficial effects of the first aspect and any of its implementations, which will not be elaborated here.

[0028] Thirdly, an information transmission method is provided, the method comprising: during the process of a first terminal's serving radio access network (RAN) switching from a source RAN to a target RAN, a session management network element receives first indication information from the target RAN or the source RAN, the first indication information being used to indicate whether the first terminal is located in a service area indicated by service area information; the session management network element manages the session of the first terminal according to the first indication information.

[0029] In one possible implementation, the session management network element specifically receives the first indication information from the target RAN through the interface between the target RAN and the session management network element; or, the session management network element specifically receives the first indication information from the source RAN through the interface between the source RAN and the session management network element.

[0030] In one possible implementation, the service area information includes the service area restriction SAR information of the first terminal, and / or the service area information of the data network corresponding to the session of the first terminal.

[0031] In one possible implementation, the first indication information is used to indicate whether the first terminal is located in the permitted area indicated by the SAR information of the first terminal, and / or whether the first terminal is located in the service area indicated by the service area information of the data network corresponding to the session of the first terminal.

[0032] In one possible implementation, the first indication information is specifically used to indicate that the first terminal is not in the permitted area indicated by the SAR information; the session management network element receives the first indication information from the target RAN or the source RAN, including: the session management network element receives a first request from the target RAN or a third request from the source RAN, the first request or the third request being used to request deactivation or release of the first terminal's session, the first request or the third request including the first indication information. The session management network element manages the first terminal's session according to the first indication information, including: the session management network element deactivates or releases the first terminal's session according to the first request or the third request.

[0033] In one possible implementation, the session management network element receives first indication information from the target RAN, including: the session management network element receives a second request from the target RAN, the second request being used to request the service RAN of the first terminal to be switched from the source RAN to the target RAN, the second request including the first indication information; the session management network element manages the session of the first terminal according to the first indication information, including: the session management network element performs session switching on the session of the first terminal according to the second request, the session switching including updating the service RAN in the session management context of the first terminal from the source RAN to the target RAN.

[0034] In one possible implementation, the session management network element receives first indication information from the source RAN, including: the session management network element receives a fourth request from the source RAN, the fourth request being used to request preparation to switch the serving RAN of the first terminal from the source RAN to the target RAN, the fourth request including the first indication information; the session management network element manages the session of the first terminal according to the first indication information, including: the session management network element determines whether to modify the user plane network element corresponding to the session of the first terminal according to the fourth request.

[0035] Fourthly, an information transmission method is provided, comprising: a session management network element acquiring service area information corresponding to a first terminal; during the process of the first terminal's service RAN switching from a source RAN to a target RAN, the session management network element receiving a first request from the source RAN or the target RAN, the first request being used to request the first terminal's service RAN to be switched from the source RAN to the target RAN, the first request including the location information of the first terminal; the session management network element determining whether the first terminal is located in the service area indicated by the service area information based on the location information and service area information of the first terminal; and the session management network element managing the session of the first terminal based on whether the first terminal is located in the service area indicated by the service area information.

[0036] In this embodiment, the session management network element obtains the service area information corresponding to the first terminal. Then, during the handover process from the source RAN to the target RAN, it can respond to a first request sent by the source RAN or the target RAN and determine whether the first terminal is located within the service area indicated by the service area information based on its location information and the service area information. This allows it to determine which sessions of the first terminal need to be switched, or whether sessions need to be deactivated or released. Therefore, the solution 2 provided in this embodiment can reliably manage sessions during the handover process while decoupling the session-related functions of the AMF.

[0037] In addition, since the session management network element can determine whether the first terminal is located in the service area indicated by the service area information corresponding to the first terminal after receiving the first handover request from the target RAN, the handover signaling sent by the target RAN to the session management network element and the access mobility management network element respectively does not have timing requirements. This can better decouple the functions of the access mobility network element and the session management network element, and further enhance flexibility.

[0038] Fifthly, an information transmission method is provided, comprising: during the process of a first terminal's serving RAN switching from a source RAN to a target RAN, an access mobility management element receives third indication information from the target RAN, the third indication information being used to instruct the first terminal's serving RAN to switch from the source RAN to the target RAN; the access mobility management element determines first indication information based on the location information of the first terminal and the service area information corresponding to the first terminal, the first indication information being used to indicate whether the first terminal is located within the service area indicated by the service area information; the access mobility management element sends the first indication information to the target RAN or a data management element, the target RAN or data management element being used to provide the first indication information to a session management element, the session management element being used to manage the session of the first terminal.

[0039] It is understandable that when the session-related functions of the access mobility management network element are decoupled, the session management network element is selected by the source RAN of the terminal. That is, the access mobility management network element does not know the correspondence between the terminal's session and the session management network element, and the access network mobility management network element cannot interact with the session management network element corresponding to the terminal's session.

[0040] In this embodiment, the Access Mobility Management (AMM) element can respond to the third indication information sent by the target RAN (e.g., carried by handover signaling) and determine whether the first terminal is located within the service area indicated by the service area information based on the location of the first terminal and the service area information corresponding to the first terminal. It then transmits this information (the first indication information) to the target RAN or the Data Management (DM) element. The target RAN or DM element can then transmit the first indication information to the Session Management (SM) element, enabling the SM element to determine which sessions of the first terminal require handover, or to deactivate or release sessions based on the first indication information. Therefore, the information transmission method provided in this embodiment can reliably manage sessions during handover while decoupling the AMF's session-related functions.

[0041] Sixthly, a communication apparatus is provided for implementing the various methods described above. This communication apparatus can be a target RAN, source RAN, session management network element, or access mobility management network element as described in any of the above aspects or implementations thereof, or an apparatus containing the aforementioned target RAN, source RAN, session management network element, or access mobility management network element, or an apparatus included in the aforementioned target RAN, source RAN, session management network element, or access mobility management network element, such as a chip. The communication apparatus includes modules, units, or means corresponding to the above methods, which can be implemented in hardware, software, or by hardware executing corresponding software. The hardware or software includes one or more modules or units corresponding to the above functions.

[0042] In some possible designs, the communication device may include a processing module and a transceiver module. The transceiver module, also referred to as a transceiver unit, is used to implement the transmission and / or reception functions in any of the above aspects and their possible implementations. The transceiver module may consist of transceiver circuits, transceivers, transceivers, or communication interfaces. The processing module can be used to implement the processing functions in any of the above aspects and their possible implementations.

[0043] In some possible designs, the transceiver module includes a sending module and a receiving module, which are used to implement the sending and receiving functions in any of the above aspects and any possible implementation methods.

[0044] A seventh aspect provides a communication device, comprising: at least one processor; said processor being configured to execute a computer program or instructions to cause the communication device to perform the method described in any of the preceding aspects.

[0045] In one possible implementation, the communication device further includes the memory. Optionally, the memory is coupled to the processor; the memory may be integrated with the processor, or it may be independent of the processor. Optionally, the processor is used to execute computer programs or instructions stored in the memory.

[0046] In one possible implementation, the memory is independent of the communication device.

[0047] In one possible implementation, the communication device further includes a communication interface for communicating with modules outside the communication device.

[0048] The communication device can be a target RAN, source RAN, session management network element, or access mobility management network element in any of the above aspects or any implementation thereof, or a device containing the target RAN, source RAN, session management network element, or access mobility management network element, or a device included in the target RAN, source RAN, session management network element, or access mobility management network element, such as a chip.

[0049] Eighthly, a computer-readable storage medium is provided that stores a computer program or instructions that, when executed on a communication device, enable the communication device to perform the methods described in any of the preceding aspects or any implementation thereof.

[0050] Ninthly, a computer program product containing instructions is provided, which, when run on a communication device, enables the communication device to perform the methods described in any of the foregoing aspects or any implementation thereof.

[0051] In a tenth aspect, a communication device (e.g., the communication device may be a chip or a chip system) is provided, the communication device including a processor for implementing the functions involved in any of the above aspects or any implementation thereof.

[0052] In some possible designs, the communication device includes a memory for storing necessary program instructions and data.

[0053] In some possible designs, when the device is a chip system, it can be composed of chips or contain chips and other discrete components.

[0054] It is understood that when the communication device provided by any one of the sixth to tenth aspects is a chip, the aforementioned transmitting action / function can be understood as an output, and the aforementioned receiving action / function can be understood as an input.

[0055] The technical effects of any of the design methods in aspects six through ten can be found in the technical effects of the different design methods in aspects one through five above, and will not be repeated here.

[0056] Eleventhly, a communication method is provided, which includes the method described in any of the above aspects or any implementation thereof.

[0057] In a twelfth aspect, a communication system is provided, comprising at least one device and / or network element as described in any of the preceding aspects and any implementation thereof: a target RAN, a source RAN, a session management network element, or an access mobility management network element. Attached Figure Description

[0058] Figure 1This is a schematic diagram of a 5GS service architecture provided in an embodiment of this application;

[0059] Figure 2 This is a schematic diagram of an Xn switching process provided in an embodiment of this application;

[0060] Figure 3 This is a schematic diagram of an N2 switching process provided in an embodiment of this application;

[0061] Figure 4 This is a schematic diagram of an architecture for sending a handover request under a distributed NAS signaling architecture provided in an embodiment of this application;

[0062] Figure 5 This is a schematic diagram of a possible, non-limiting system architecture provided in an embodiment of this application;

[0063] Figure 6 This application provides a method based on... Figure 5 The diagram illustrates the different solutions offered by the system architecture shown.

[0064] Figures 7-21 This is a flowchart illustrating an information transmission method provided in an embodiment of this application;

[0065] Figures 22-23 This is a schematic diagram of the structure of a communication device provided in an embodiment of this application. Detailed Implementation

[0066] The technical solutions of this application embodiment can be applied to various communication systems, such as Wi-Fi wireless network systems, vehicle-to-everything (V2X) communication systems, device-to-device (D2D) communication systems, vehicle-to-everything (V2X) communication systems, fourth-generation (4G) mobile communication systems, such as long-term evolution (LTE) systems, worldwide interoperability for microwave access (WiMAX) communication systems, fifth-generation (5G) mobile communication systems, such as new radio (NR) systems, and future communication systems.

[0067] To facilitate understanding of the technical solutions provided in the embodiments of this application, a brief introduction to the relevant technical terms is given first. The brief introduction is as follows:

[0068] First, the 5G system (5GS):

[0069] 5GS can include: access network (AN) and core network (CN), and can also include: terminals.

[0070] The aforementioned terminal can be a terminal with transceiver capabilities, or a chip or chip system that can be installed on the terminal. This terminal can also be referred to as user equipment (UE), access terminal, user unit, user station, mobile station (MS), mobile station, remote station, remote terminal, mobile device, user terminal, terminal, wireless communication equipment, user agent, or user apparatus. The terminals in the embodiments of this application may be mobile phones, cellular phones, smartphones, tablets, wireless data cards, personal digital assistants (PDAs), wireless modems, handsets, laptop computers, machine-type communication (MTC) terminals, computers with wireless transceiver capabilities, virtual reality (VR) terminals, augmented reality (AR) terminals, wireless terminals in industrial control, wireless terminals in self-driving, wireless terminals in remote medical care, wireless terminals in smart grids, wireless terminals in transportation safety, wireless terminals in smart cities, wireless terminals in smart homes, vehicle-mounted terminals, roadside units (RSUs) with terminal functions, etc. The terminal of this application may also be an on-board module, on-board unit, on-board component, on-board chip or on-board unit that is built into a vehicle as one or more components or units.

[0071] The aforementioned AN is used to implement access-related functions, providing network access capabilities for authorized users and determining transmission links of different quality levels to transmit user data based on user level, service requirements, etc. The AN forwards control signals and user data between the terminal and the CN. The AN may include access network equipment, also known as radio access network (RAN) equipment.

[0072] The Network Center (CN) is primarily responsible for maintaining the subscription information of the mobile network and providing terminals with functions such as session management, mobility management, policy management, and security authentication. The CN mainly includes all or some of the following functions: User Plane Function (UPF), Authentication Server Function (AUSF), Access and Mobility Management Function (AMF), Session Management Function (SMF), Network Slice Selection Function (NSSF), Network Exposure Function (NEF), Network Repository Function (NRF), Policy Control Function (PCF), Unified Data Management (UDM), Unified Data Repository (UDR), and Application Function (AF).

[0073] Figure 1 This is a schematic diagram of a 5GS service architecture provided in an embodiment of this application. For example... Figure 1 As shown, the UE accesses the 5G network through the RAN, and communicates with the AMF through the N1 interface (N1); the RAN communicates with the AMF through the N2 interface (N2); the RAN communicates with the UPF through the N3 interface (N3); the SMF communicates with the UPF through the N4 interface (N4); and the UPF accesses the data network (DN) through the N6 interface (N6). Furthermore, Figure 1The control plane functions shown, such as AUSF, AMF, SMF, NSSF, NEF, NRF, PCF, UDM, UDR, or AF, interact using service-oriented interfaces. For example, the service-oriented interface provided by AUSF is Nausf; AMF is Namf; SMF is Nsmf; NSSF is Nnssf; NEF is Nnef; NRF is Nnrf; PCF is Npcf; UDM is Nudm; UDR is Nudr; and AF is Naf.

[0074] RAN can be a device or logical entity that provides access to terminals. For example, RAN can include: access network equipment in a future communication system, or a base station; or in a future communication system, the RAN can also have other naming conventions, all of which are covered within the protection scope of the embodiments of this application, and this application does not limit them in any way. Alternatively, RAN can also include 5G, such as gNB in ​​a new radio (NR) system, or one or a group of antenna panels (including multiple antenna panels) of a base station in 5G, or it can also be a network node constituting a gNB, transmission and reception point (TRP) or transmission point (TP) or transmission measurement function (TMF), such as a building base band unit (BBU), or a centralized unit (CU) or distributed unit (DU), an RSU with base station function, or a wired access gateway, or the core network of 5G. Alternatively, RAN may also include access points (APs) in wireless fidelity (Wi-Fi) systems, wireless relay nodes, wireless backhaul nodes, various forms of macro base stations, micro base stations (also known as small stations), relay stations, access points, wearable devices, or vehicle-mounted devices, etc.

[0075] The User-Defined Processing (UPP) is primarily responsible for user data processing (forwarding, receiving, billing, etc.). For example, the UPF can act as a session point (or endpoint) for external Protocol Data Unit (PDU) sessions connected to the Data Network (DN), handling packet routing and forwarding, user plane policy rule enforcement and packet inspection, and user plane Quality of Service (QoS) processing. The DN can refer to the operator's network providing data transmission services to users, such as Internet Protocol (IP) Multimedia Service (IMS) or the Internet. The DN can be an external network of the operator or a network controlled by the operator, used to provide services to terminals.

[0076] It is understandable that the core of the user plane is establishing a PDU session, that is, establishing a PDU session between the terminal and the DN, and providing end-to-end (E2E) user plane connectivity through the PDU session. The two ends (or session points) of the PDU session are the terminal and the UPF, and the RAN is used to transparently forward data packets transmitted between the terminal and the UPF. In addition, the PDU session can include the transmission path between the DN and the UPF network elements, and the transmission path (or tunnel) between the UPF and the RAN. This tunnel can be a General Packet Radio Service Tunneling Protocol for the User Plane (GTP-U) tunnel, which is used to carry data packets transmitted in the user plane.

[0077] Additionally, within a PDU session, the UPF can include a Protocol Data Unit Session Anchor (PSA), also known as a PSA-UPF. A PSA UPF can refer to a UPF directly connected to the DN via N6. It should be understood that a PDU session can also include an intermediate PDU (I-UPF), which is used to transmit user plane data between the RAN and the PSA-UPF.

[0078] AUSF is primarily used to perform security authentication for terminals.

[0079] AMF is primarily used for mobility management in mobile networks. Examples include user location updates, user network registration, and user handover.

[0080] SMF is primarily used for session management in mobile networks. This includes tasks such as session establishment, modification, and release. Specific functions include assigning IP addresses to users and selecting a UPF (User-Defined Provider) to handle packet forwarding.

[0081] The PCF primarily supports providing a unified policy framework to control network behavior, delivering policy rules to control-layer network functions, and acquiring user subscription information related to policy decisions. The PCF can provide policies to the AMF and SMF, such as Quality of Service (QoS) policies and slice selection policies.

[0082] NSSF is primarily used to select network slices for terminals.

[0083] NEF is primarily used to support the opening of capabilities and events.

[0084] UDM is primarily used to store user data, such as contract information and authentication / authorization data.

[0085] UDR is primarily used to store structured data, including contract information and policy data, externally exposed structured data, and application-related data.

[0086] AF primarily supports interaction with CN to provide services, such as influencing data routing decisions, policy control functions, or providing third-party services to the network side.

[0087] It is understood that the functions mentioned in the embodiments of this application can also refer to functional network elements or functional entities. For example, RAN can be referred to as NEF network element, or RAN equipment, or RAN device, etc., and SMF can be referred to as SMF network element, and so on, without limitation.

[0088] In addition, the terms "function" and "functional network element" are used interchangeably in the following text. For example, "SMF" and "SMF network element" are used interchangeably. They have the same meaning and will be explained uniformly here. They will not be repeated below.

[0089] Second, the switching process:

[0090] It is understandable that after a UE registers with the network, a PDU session can be established to enable communication between services and a specific DN. The network can configure relevant policies to control whether a UE can connect to certain DNs within a specific service area. These policies can be UE-level or DN-level. For example, when a UE moves from one cell to another, it needs to connect to the new cell via either the Xn or N2 handover procedure. During the handover process, the AMF needs to determine whether the UE can continue using the established PDU session based on the location information of the cell the UE is switching to.

[0091] The following describes the service areas, Xn handover, and N2 handover involved in the above handover process.

[0092] 2.1 Service Area:

[0093] During the handover process, the service area involves the DN-side service area (e.g., the local area data network (LADN)) and the service area used for UE mobility management (e.g., service area restriction (SAR)), which will be explained below.

[0094] The service area indicated by the LADN can be represented by one or more tracing areas (TAs) and / or cells, within which service communication (or service transmission) can take place. It is understood that the LADN can be associated with a DN and / or a slice network. Furthermore, the LADN can be provided by a DN or single network slice selection assistance information (S-NSSAI).

[0095] SAR defines which areas a UE can communicate with the network to transmit certain services (e.g., non-urgent services) and which areas a UE is not allowed to communicate with the network to transmit services. It can be understood that the service area indicated by SAR can include allowed areas and non-allowed areas. Specifically, a UE can transmit non-urgent services within allowed areas, but cannot do so within non-allowed areas. For example, if a UE is in a non-allowed area, neither the UE nor the network is allowed to initiate service requests or session management (SM) signaling for non-urgent service transmission, but emergency service transmission is permitted. Another example is that if a UE enters a non-allowed area, network selection or cell reselection may not be triggered. Yet another example is that if a UE is in a non-allowed area, emergency service transmission is permitted; however, this embodiment does not specifically limit these limitations.

[0096] It should be understood that when the UE is located in an unauthorized area, the UE can camp in the unauthorized area and can transmit some non-emergency services, but cannot transmit emergency services.

[0097] It is understandable that the aforementioned SAR is mainly used for mobility management and belongs to the AMF-related policy. The aforementioned LADN is a service area restriction for data networks and belongs to the session (i.e., SMF)-related policy.

[0098] 2.2 Xn switching:

[0099] Xn is the interface for interaction between RANs. Xn handover is mainly used when the UE has a small mobility range and does not involve handover across AMFs. That is, after the UE's serving RAN is switched from the source RAN (S-RAN) to the target RAN (T-RAN), the AMF on the CN side does not change.

[0100] Figure 2 This is a schematic diagram of an Xn switching process provided in an embodiment of this application. For example... Figure 2 As shown, this process mainly involves the interaction between the UE, source RAN, target RAN, AMF, SMF, and UPF.

[0101] like Figure 2 As shown, the switching process for Xn includes the following steps:

[0102] S201. Handover preparation.

[0103] It is understandable that when a UE moves from the coverage area of ​​the source RAN to the coverage area of ​​the T-RAN, the UE should switch from the source RAN to the target RAN. The target RAN can obtain the UE's temporary identifier and session-related information (such as PDU session identifier (ID), UE context information, etc.) from the source RAN through the Xn interface for PDU session transmission.

[0104] It is understood that step S201 may include RAN handover completion, meaning that the UE has completed the air interface handover. For example, after the UE's air interface connection is switched from the source RAN to the target RAN, the UE may send an RRC Reconfiguration Complete message to the target RAN, which is used to indicate that the air interface handover is complete.

[0105] S202. The target RAN sends an N2 path switch request to the AMF. Correspondingly, the AMF receives the N2 path switch request from the target RAN. The N2 path switch request may include: a list of PDU sessions to be switched, a list of PDU sessions that failed to switch, the UE's temporary identifier, or the UE's location information, etc.

[0106] It should be understood that the UE's location information can be indicated by the area where the UE is located. This area could be, for example, the coverage area (or service area) of the target RAN, or the service area of ​​the UE could be determined by the identifier of the target RAN. For instance, an N2 path handover request could include the identifier of the TA (e.g., TA identity (TAI) or TA code (TAC)) where the UE is located, or the identifier of the cell where the UE is located, or the identifier of the service area of ​​the target RAN (e.g., the identifier of the TA or cell served by the target RAN). As another example, an N2 path handover request could include the identifier of the target RAN, so the AMF can determine that the UE's location is within the service area of ​​the target RAN based on the identifier of the target RAN.

[0107] S203. The AMF sends a session modification (or update) request to the SMF. Correspondingly, the SMF receives the session modification request from the AMF. The session modification request is used to modify the session management (SM) context.

[0108] It is understandable that the AMF sends a session modification request to the SMF corresponding to each of the UE's multiple sessions. That is, during the UE handover process, session management is performed at the granularity of the UE's PDU session.

[0109] Alternatively, AMF can send the aforementioned session modification request by calling the SMF's PDU session update SM context request (Nsmf_PDUSession_UpdateSMContext Request) service operation.

[0110] It is understood that the AMF can send a corresponding session update request based on whether the UE is located in the service area indicated by the aforementioned service area information. Specifically, the AMF can obtain the UE's subscription data from the UDM, which may include the UE's SAR information. Then, the AMF can determine whether the UE is located in an allowed area based on the UE's location information included in the N2 path handover request in step S202, as well as the UE's SAR information.

[0111] If the AMF determines that the UE is not in the permitted area indicated by the SAR information, then the UE is not allowed to establish any sessions other than emergency service sessions (i.e., the UE is not allowed to establish non-emergency service sessions). Therefore, the aforementioned session modification request may include indication information indicating that the UE is not in the permitted area indicated by the SAR information. Thus, the AMF can send this indication information to the SMF corresponding to each of the UE's multiple sessions, so that the SMF can activate or release other sessions in the UE's multiple sessions other than those used for emergency services based on the indication information, thereby enabling the SMF to activate or release non-emergency service sessions in the UE's multiple sessions.

[0112] For example, the AMF can send the above indication information to the SMF corresponding to each of the UE's multiple sessions by calling the AMF's event exposure notification (Namf_EventExposure_Notify) service operation.

[0113] It is understood that the aforementioned deactivation or release of the session, or session deactivation or release, may refer to the SMF releasing PDU session resources, including releasing the UPF corresponding to the PDU session.

[0114] If the AMF determines that the UE is located in the permitted area indicated by the SAR information, then the AMF can determine whether the UE is located in the service area indicated by the LADN information associated with each of the UE's multiple sessions (which may be pre-configured).

[0115] For example, if the AMF determines that the UE is located in the service area indicated by the LADN information associated with a certain session among the UE's multiple sessions, then the session modification request sent by the AMF to the SMF corresponding to that session can include indication information indicating that the UE is located in the service area indicated by the LADN information, so that the SMF can perform session switching for that session based on the indication information.

[0116] It is understood that session handover may include modifying the information of the serving RAN in the session management context from the source RAN to the target RAN. For example, session handover may include configuring the tunnel between the UPF corresponding to the session and the access side (i.e., the target RAN, or the RAN addressed by N3). It is understood that session handover may also include modifying (e.g., adding (inserting), deleting, or updating) the I-UPF, and / or data forwarding rules (e.g., QoS flow information), etc., which are not specifically limited in this embodiment.

[0117] For example, if the AMF determines that the UE is not in the service area indicated by the LADN information associated with a certain session among the UE's multiple sessions, then the session modification request sent by the AMF to the SMF corresponding to that session may not include the indication information used to indicate that the UE is in the service area indicated by the LADN information, thereby implicitly indicating that the UE is not in the service area indicated by the LADN information, thus causing the SMF to release or deactivate the session.

[0118] It should be understood that the session management performed by the SMF side based on the session modification request is mainly related to the UPF. The interaction between SMF and UPF is described in detail below.

[0119] S204. The SMF sends an N4 session modification request to the UPF. Correspondingly, the UPF receives the N4 session modification request from the SMF.

[0120] Among them, N4 session modification requests can include session switching, or session deactivation or release.

[0121] S205. The UPF sends an N4 session modification response to the SMF. Correspondingly, the SMF receives the N4 session modification response from the UPF.

[0122] It is understandable that an N4 session modification response can be used to indicate that a session modification was successful. For example, a session switch was successful, or a session was successfully deactivated or released.

[0123] S206, UPF sends the N3 end marker to the source RAN.

[0124] It is understandable that the N3 end marker is used to indicate that the UPF has ended sending data packets to the source RAN.

[0125] S207. The source RAN sends the N3 end marker to the target RAN.

[0126] S208. The SMF sends a session modification response to the AMF. Correspondingly, the AMF receives the session modification response from the SMF.

[0127] The session modification response indicates that the session modification was successful, meaning that the session management context was successfully updated.

[0128] It is understandable that SMF can send the aforementioned session modification response by calling the SMF's PDU session update SM context response (Nsmf_PDUSession_UpdateSMContext Response) service operation.

[0129] S209. The AMF sends an N2 path handover request acknowledgment (ACK) to the target RAN. Correspondingly, the target RAN receives the N2 path handover request acknowledgment from the AMF.

[0130] S210, the target RAN sends a resource release message to the source RAN. Correspondingly, the source RAN receives the resource release message from the target RAN.

[0131] The resource release message is used to instruct the source RAN to release relevant resources of the UE, such as radio and control plane resources.

[0132] Optionally, Figure 2 The process shown also includes:

[0133] The S211, UE, target RAN, and AMF perform a registration procedure.

[0134] It is understandable that N2 handover is different from Xn handover. Because the UE moves a long distance, the source RAN may not be able to find the target RAN through the Xn interface. The source RAN can find the target RAN through the source AMF, which will be explained in detail below.

[0135] Figure 3 This is a schematic diagram of an N2 switching process provided in an embodiment of this application. For example... Figure 3 As shown, the N2 handover is divided into a preparation phase and an execution phase. Among them, as... Figure 3 As shown, the preparation stage includes the following steps:

[0136] S301. The source RAN sends a handover required message to the source AMF. Correspondingly, the source AMF receives the handover required message from the source AMF.

[0137] The handover request message includes: the identifier of the target RAN, security information sent to the target RAN, or a list of mobility restrictions, etc.

[0138] S302, Source AMF selects target AMF.

[0139] It is understandable that the source AMF can select the target AMF to serve the target RAN based on the handover requirement message.

[0140] S303, the source AMF sends a UE context establishment request to the target AMF. Correspondingly, the target AMF receives the UE context establishment request from the source AMF.

[0141] The UE context establishment request includes the UE's identifier, SAR information, UE's session information, and session-associated SMF information.

[0142] S304. The target AMF sends a session modification request to the SMF. Accordingly, the SMF receives the session modification request from the target AMF.

[0143] It is understood that the specific implementation of step S304 here is similar to that of step S203, the difference being that: since step S304 is in the handover preparation phase, it determines whether the UE is located in the allowed area indicated by the SAR information, while determining whether the UE is located in the service area indicated by the LADN information associated with each session is performed in the handover execution phase. Furthermore, the specific implementation of step S304 can be found in step S203.

[0144] S305, Session Management.

[0145] As can be understood, as described in the aforementioned step S203, session management may include session switching, session deactivation, or release. Specifically, in step S305, the SMF can determine whether a new UPF is needed for the session based on the session modification request in step S304. If a new UPF is not needed, steps S305a and S305b are executed. Alternatively, if a new UPF is needed (e.g., the UE is not in the service area of ​​the source UPF (i.e., PSA-UPF), a target UPF is selected. After the SMF selects the target UPF, steps S305c and S305d can be executed.

[0146] S305a: The SMF sends an N4 session modification request to the PSA-UPF. Correspondingly, the PSA-UPF receives the N4 session modification request from the SMF.

[0147] It is understood that the specific implementation of step S305a can be found in step S204, and will not be repeated here.

[0148] S305b, PSA-UPF sends an N4 session modification response to SMF. Correspondingly, SMF receives the N4 session modification response from UPF.

[0149] It is understood that the specific implementation of step S305b can be found in step S205, and will not be repeated here.

[0150] S305c: The SMF sends an N4 session establishment request to the target UPF. Correspondingly, the target UPF receives the N4 session establishment request from the SMF.

[0151] Among them, the N4 session establishment request is used to establish a tunnel between the target UPF and the target AMF.

[0152] S305d, the target UPF sends an N4 session establishment response to the SMF. Correspondingly, the SMF receives the N4 session establishment response from the target UPF.

[0153] The N4 session establishment response is used to indicate that the session was successfully established.

[0154] It is understood that the session management process in step S305 above may also include inserting a new I-UPF, which will not be elaborated here.

[0155] S306. The SMF sends a session modification response to the target AMF. Accordingly, the target AMF receives the session modification response from the SMF.

[0156] It is understandable that the session modification response is used to indicate that the session modification was successful, that is, the session management context was successfully updated.

[0157] In addition, the above steps S304 to S306 are mainly used for the target AMF to obtain the tunnel information of the UPF.

[0158] S307. The target AMF sends a handover request to the target RAN. Accordingly, the target RAN receives the handover request from the target AMF.

[0159] It is understandable that the target AMF can send a handover request to the target RAN based on the target RAN's identifier. Furthermore, the handover request may include security information from the source RAN, mobility restriction lists, and other information.

[0160] S308. The target RAN sends a handover request ACK to the target AMF. Correspondingly, the target AMF receives the handover request ACK from the target RAN.

[0161] The handover request confirmation may include information such as the container to be sent to the source RAN, a list of PDU sessions that can be switched, or PDU sessions that cannot be switched.

[0162] It is understandable that the target RAN can also allocate a new temporary air interface identifier to the UE based on the handover request, so as to facilitate session management in the subsequent execution phase.

[0163] S309. The target AMF sends a PDU session update session management context request to the SMF. Correspondingly, the SMF receives the session from the target AMF.

[0164] It is understandable that, based on the target RAN's handover request response, the target AMF sends a PDU session update request to the SMF corresponding to the PDU session. Specifically, for sessions undergoing handover, the AN-side tunnel information of the session is updated; for sessions that cannot be handed over, the corresponding session is requested to be released by the SMF.

[0165] It should be understood that the main purpose of step S309 is to facilitate the exchange of tunnel information between the target RAN, the target UPF, and the source UPF. For example, after step S309, the SMF can send an N4 session modification request to the target UPF or the source UPF, and then receive an N4 session request response from the target UPF or an N4 session modification response from the source UPF, which will not be elaborated further here.

[0166] S310, the SMF sends a PDU session update session management context response to the target AMF. Correspondingly, the target AMF receives the PDU session update session management context response from the SMF.

[0167] It is understood that the specific implementation of step S310 can be found in step S306, and will not be repeated here.

[0168] S311, The target AMF sends a UE context establishment response to the source AMF. Correspondingly, the source AMF receives the UE context establishment response from the target AMF.

[0169] It is understandable that after step S311, the source AMF, the target AMF, and the target RAN exchanged information about the forwarding path, preparing for the handover.

[0170] like Figure 3 As shown, the execution phase includes the following steps:

[0171] S312, RAN handover complete.

[0172] It can be understood that RAN handover completion means that the UE has completed the air interface handover. Furthermore, the difference between step S312 and step S201 is that the source AMF sends a handover command to the source RAN, which in turn sends a handover command to the UE, enabling the UE and the target RAN to complete the air interface handover. That is, RAN handover completion is executed under the trigger of the handover command. For example, after the UE and the cell where the target RAN resides complete synchronization, the UE sends a handover confirmation to the target RAN, indicating that the air interface handover is complete.

[0173] S313. The target RAN sends a handover notification to the target AMF. Correspondingly, the target AMF receives the handover notification from the target RAN.

[0174] The handover notification is used to inform the target AMF that the air interface handover has been completed. The handover notification may include: the UE's temporary identifier and the UE's location information (such as TA identifier or cell identifier).

[0175] S314. The target AMF sends a session modification request to the SMF. Accordingly, the SMF receives the session modification request from the target AMF.

[0176] It should be understood that the specific implementation of step S314 is related to... Figure 2 Similar to step S203, based on the UE's location, SAR information, and session-associated LADN information, it is determined whether the UE is located in the allowed area indicated by the SAR information and whether the UE is located in the service area indicated by the LADN information. For details, please refer to step S203, which will not be repeated here.

[0177] S315, Session Management.

[0178] As can be understood, as explained in the aforementioned step S305, depending on whether the UE is located in the service area indicated by the service area information and whether a new UPF has been added, the SMF can send a session modification request to the target UPF, the source UPF, or the PSA-UPF, and then receive a session modification response from the target UPF, the source UPF, or the PSA-UPF. This will not be elaborated further here.

[0179] S316. The SMF sends a session modification response to the target AMF. Accordingly, the target AMF receives the session modification response from the SMF.

[0180] S317. Registration process.

[0181] As can be understood from the above descriptions regarding Xn and N2 handover, during UE handover, the AMF determines whether the UE's PDU session can be established (i.e., whether it needs to be deactivated or released) based on whether the UE is located within the permitted area indicated by the SAR information and the service area indicated by the LADN information, and then sends a session modification request to the SMF. In other words, in addition to being responsible for UE location determination (i.e., mobility management), the AMF is also responsible for functions related to session management (sending session modification requests to the SMF). Furthermore, all interactions between the RAN and other NFs in the core network besides the AMF are forwarded through the AMF, which leads to poor flexibility.

[0182] Therefore, in order to meet the new demands of future services, it is necessary to improve the existing 5GS architecture of the future communication network (or future communication system) to enhance the flexibility of UE interaction with NF in the core network and meet the new demands of future services. The following is a detailed description of the relevant improvements to the 5GS architecture.

[0183] Third, distributed non-access stratum (NAS) architecture:

[0184] In current research on future communication networks (or future communication systems), a distributed NAS signaling architecture can be adopted between the RAN and the core network. This allows the RAN to send relevant messages to the AMF and SMF respectively. As a result, the RAN does not have to send all NAS signaling to the AMF and have it forwarded centrally by the AMF, thus decoupling the AMF function and enhancing flexibility.

[0185] Understandably, in a distributed NAS architecture, the RAN can discover NFs in the CN through NRF discovery or other means, and then directly communicate with different NFs in the CN. For example, the RAN can achieve signaling interaction through the service interface between the RAN and the NF.

[0186] Figure 4 This is a schematic diagram illustrating the architecture of a distributed NAS signaling architecture for sending handover requests, as provided in an embodiment of this application. Figure 4 As shown, when a distributed NAS architecture is adopted, the RAN can discover NFs such as AMF and SMF through NRF. The RAN can directly send NAS signaling to the AMF and SMF in the core network through the service interface.

[0187] For example, during the handover of a UE's serving RAN from a source RAN to a target RAN, the source RAN can select a Service Provider (SMF) and pass the UE's temporary identifier and session-related information (including the SMF corresponding to each of the UE's multiple sessions) to the target RAN. The target RAN can send a first path handover request to the AMF and a second path handover request to the SMF. The first path handover request instructs the UE's serving RAN to switch from the source RAN to the target RAN, allowing the AMF to update the UE's serving RAN information accordingly. The second path handover request can be used to request a handover of the UE's serving RAN from the source RAN to the target RAN, enabling the SMF to perform session management (e.g., session handover, session deactivation, or release), i.e., update tunnel information and notify the session-associated UPF.

[0188] Understandable, adopt Figure 4 The method shown improves flexibility by decoupling the session-related functions of the AMF. However, there is still no solution to ensure reliable session management during handover based on regional limitations.

[0189] Specifically, see Figure 4Decoupling the session-related functions of the AMF means that the AMF will not send session modification requests to the SMF (see step S203 for details). The SMF will only receive second path handover requests from the RAN. This will cause the SMF to be unable to determine whether the UE is located in the allowed area indicated by the UE's SAR information and / or the service area indicated by the LADN information corresponding to the UE's session. Therefore, the SMF cannot determine which sessions need to be deactivated or released, and which sessions need to be switched.

[0190] To address the aforementioned technical problems, this application provides the following technical solutions, which will be described below with reference to the accompanying drawings.

[0191] In the embodiments of this application, "instruction" can include direct and indirect instructions, as well as explicit and implicit instructions. The information indicated by a certain piece of information is called the information to be instructed. In the specific implementation process, there are many ways to instruct the information to be instructed, such as, but not limited to, directly instructing the information to be instructed, such as the information to be instructed itself or its index. It can also indirectly instruct the information to be instructed by instructing other information, where there is a relationship between the other information and the information to be instructed. It can also instruct only a part of the information to be instructed, while the other parts are known or pre-agreed upon. For example, the instruction of specific information can be achieved by using a pre-agreed (e.g., protocol-defined) arrangement of various pieces of information, thereby reducing instruction overhead to some extent. At the same time, common parts of various pieces of information can be identified and uniformly indicated to reduce the instruction overhead caused by individually indicating the same information.

[0192] Furthermore, the specific indication method can also be any existing indication method, such as, but not limited to, the above-mentioned indication methods and their various combinations. Specific details of various indication methods can be found in existing technologies, and will not be repeated here. As described above, for example, when multiple pieces of information of the same type need to be indicated, the indication methods for different pieces of information may differ. In the specific implementation process, the required indication method can be selected according to specific needs. This application embodiment does not limit the selected indication method; therefore, the indication methods involved in this application embodiment should be understood to cover various methods that enable the party to be indicated to obtain the information to be indicated.

[0193] It should be understood that the information to be indicated can be sent as a whole or divided into multiple sub-information messages sent separately, and the sending period and / or timing of these sub-information messages can be the same or different. The specific sending method is not limited in this application embodiment. The sending period and / or timing of these sub-information messages can be predefined, for example, according to a protocol, or configured by the sending device by sending configuration information to the receiving device.

[0194] In this application, "sending information" can be understood as one device (or communication entity) sending information to another device (or communication entity), or it can be understood as one logical module within a device sending information to another logical module. For example, "RAN sending information" can be understood as the RAN sending information to another device (such as SMF), or it can be understood as logical module 1 in the RAN sending information to logical module 2 in another device.

[0195] In this application, "receiving information" can be understood as one device (or communication entity) receiving information from another device (or communication entity), or it can be understood as a logical module within a device receiving information from another logical module. For example, "RAN (or RAN element) receiving information" can be understood as the RAN receiving information from another device (such as SMF), or it can be understood as logical module 1 in the RAN receiving information from logical module 2 in another device.

[0196] In this application, phrases such as "sending information to... (e.g., SMF)" or related illustrations in the accompanying drawings can be understood as indicating that the destination of the information is the SMF. This can include sending information directly or indirectly to the SMF. Similarly, phrases such as "receiving information from... (e.g., RAN)," "receiving information from... (e.g., RAN)," or "receiving information sent (e.g., by the RAN)," or related illustrations in the accompanying drawings, can be understood as indicating that the source of the information is the RAN. This can include receiving information directly or indirectly from the RAN. Information may undergo necessary processing between the source and destination, such as format changes, but the destination can understand the valid information from the source. Similar expressions in this application can be interpreted similarly and will not be elaborated further here.

[0197] "Predefined" or "pre-configured" can be achieved by pre-saving corresponding codes, tables, or other means that can be used to indicate relevant information in the device. This application does not limit the specific implementation method. "Saving" can refer to saving in one or more memories. These memories can be separate installations or integrated into the encoder, decoder, processor, or communication device. Alternatively, some memories can be separately installed, while others are integrated into the decoder, processor, or communication device. The type of memory can be any form of storage medium, and this application does not limit this.

[0198] The “protocol” mentioned in the embodiments of this application may refer to a protocol family in the field of communication, a standard protocol with a similar protocol family frame structure, or a related protocol applied to future communication systems. The embodiments of this application do not specifically limit this.

[0199] In the embodiments of this application, descriptions such as "when," "under the circumstances," "if," and "if" all refer to the device making corresponding processing under certain objective circumstances, and are not limited to a specific time. They do not require the device to make a judgment action during implementation, nor do they imply any other limitations.

[0200] In the description of the embodiments of this application, unless otherwise stated, " / " indicates that the objects before and after are in an "or" relationship. For example, A / B can represent A or B. "And / or" in the embodiments of this application is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, and B alone, where A and B can be singular or plural. Furthermore, in the description of the embodiments of this application, unless otherwise stated, "multiple" refers to two or more. "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, or c can represent: a, b, c, ab, ac, bc, or abc, where a, b, and c can be single or multiple. Additionally, to facilitate a clear description of the technical solutions of the embodiments of this application, the terms "first" and "second" are used in the embodiments of this application to distinguish identical or similar items with essentially the same function and effect. Those skilled in the art will understand that the terms "first," "second," etc., do not limit the quantity or order of execution, and that "first," "second," etc., are not necessarily different. Furthermore, in the embodiments of this application, words such as "exemplary" or "for example" are used to indicate that something is being used as an example, illustration, or description. Any embodiment or design scheme described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design schemes. Specifically, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner for ease of understanding.

[0201] The network architecture and business scenarios described in the embodiments of this application are for the purpose of more clearly illustrating 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.

[0202] To facilitate understanding of the embodiments of this application, a communication system will be used as an example to describe in detail the communication system applicable to the embodiments of this application.

[0203] Figure 5 This is a schematic diagram of a possible, non-limiting system architecture provided in an embodiment of this application. For example... Figure 5 As shown, the system includes: a RAN and a session management network element. The RAN can be the target RAN or the source RAN during terminal handover. The session management network element can be, for example, a network element used for session management of the terminal (e.g., Figure 1 The embodiments of this application do not specifically limit the SMF (Session Management Element) in the present invention, or the network element used for session management in a future communication system.

[0204] It should be understood that Figure 5 The system architecture shown may also include other network elements, such as access mobility management network elements or data management network elements, etc., which are not specifically limited in this application embodiment.

[0205] Additionally, access mobility management elements can refer to network elements used for mobility management in mobile networks (e.g., Figure 1 The embodiments of this application do not specifically limit the AMF (Ampere Flow Function) or the network element used for mobility management in future communication systems.

[0206] In addition, data management network elements can refer to network elements used to store terminal subscription information and / or policy data (e.g., Figure 1 The UDR in the present application, or the network element used to store the terminal's subscription information and / or policy data in a future communication system, is not specifically limited to this in the embodiments of this application.

[0207] Regarding how to ensure reliable session management during handover when decoupling session-related functions from the AMF, Figure 5 The system shown provides the following three solutions, which are discussed below. Figure 6 Please provide an explanation.

[0208] Figure 6 This application provides a method based on... Figure 5 The diagram illustrates the different solutions offered by the system architecture shown. Figure 6 As shown, Figure 6 (a) in the diagram is a schematic diagram of Scheme 1. Figure 6 (b) in the diagram is a schematic diagram of Scheme 2. Figure 6 (c) in the diagram is a schematic diagram of scheme 3.

[0209] For Option 1:

[0210] like Figure 6 As shown in (a) above, in Scheme 1, the RAN determines whether the terminal is located within the service area indicated by the service area information corresponding to the terminal, and instructs the session management network element accordingly. Scheme 1 can be divided into two sub-schemes based on the different RANs (target RAN or source RAN), which will be described below.

[0211] Option 1-1:

[0212] In one possible implementation, during the handover of the first terminal's serving RAN from the source RAN to the target RAN, the target RAN obtains the service area information corresponding to the first terminal. Based on the first terminal's location information and service area information, the target RAN determines first indication information and sends this first indication information to the session management network element. The first indication information indicates whether the first terminal is located within the service area indicated by the service area information. The session management network element manages the first terminal's session.

[0213] Option 1-2:

[0214] In one possible implementation, the source RAN obtains the corresponding service area information of the first terminal. During the process of the first terminal's service RAN switching from the source RAN to the target RAN, the source RAN determines first indication information based on the first terminal's location information and service area information, and then sends the first indication information to the session management network element. The first indication information indicates whether the first terminal is located within the service area indicated by the service area information. The session management network element manages the first terminal's sessions.

[0215] In other words, the target RAN or source RAN, by obtaining the service area information corresponding to the first terminal, can determine whether the first terminal is located within the service area indicated by the service area information based on the location information of the first terminal and the service area information. Then, it can instruct the session management network element through the first indication information, enabling the session management network element to determine which sessions of the first terminal need to be switched, or whether sessions need to be deactivated or released, based on the first indication information. Therefore, the solution 1 provided in this application embodiment can ensure reliable session management during the handover process while decoupling the session-related functions of the AMF.

[0216] Furthermore, since the target RAN or source RAN determines whether the first terminal is located in the service area indicated by the service area information corresponding to the first terminal, after the target RAN sends handover signaling to the access mobility management network element, it does not need to send handover signaling to the session management network element based on the information fed back by the access mobility management network element regarding whether the first terminal is located in the service area. Therefore, the handover signaling sent by the target RAN to the session management network element and the access mobility management network element respectively has no timing requirements, which can better decouple the functions of the access mobility network element and the session management network element and further enhance flexibility.

[0217] For option 2:

[0218] like Figure 6 As shown in (b) of the diagram, in Scheme 2, the session management network element determines whether the terminal is located in the service area indicated by the service area information corresponding to the terminal, and performs session management based on this.

[0219] In one possible implementation, the session management network element obtains the service area information corresponding to the first terminal; during the process of the first terminal's service RAN switching from the source RAN to the target RAN, the session management network element receives a first request from the source RAN or the target RAN, the first request being used to request the first terminal's service RAN to be switched from the source RAN to the target RAN, the first request including the location information of the first terminal; the session management network element determines whether the first terminal is located in the service area indicated by the service area information based on the location information and service area information of the first terminal; the session management network element manages the session of the first terminal based on whether the first terminal is located in the service area indicated by the service area information.

[0220] In other words, by obtaining the service area information corresponding to the first terminal, the session management network element can, during the process of the first terminal's service RAN switching from the source RAN to the target RAN, respond to a first request sent by the source RAN or the target RAN. Based on the location information of the first terminal and the service area information, it can determine whether the first terminal is located in the service area indicated by the service area information, thereby determining which sessions of the first terminal need to be switched, or whether sessions need to be deactivated or released. Therefore, the solution 2 provided in this application embodiment can ensure reliable session management during the handover process while decoupling the session-related functions of the AMF.

[0221] In addition, since the session management network element can determine whether the first terminal is located in the service area indicated by the service area information corresponding to the first terminal after receiving the first handover request from the target RAN, the handover signaling sent by the target RAN to the session management network element and the access mobility management network element respectively does not have timing requirements. This can better decouple the functions of the access mobility network element and the session management network element, and further enhance flexibility.

[0222] For option 3:

[0223] like Figure 6 As shown in (c), in Scheme 3, the access mobility management network element determines whether the terminal is located in the service area indicated by the service area information corresponding to the terminal, and sends the determination result to the target RAN or data management network element, so that the session management network element can obtain the determination result from the target RAN or data management network element.

[0224] In one possible implementation, during the process of the first terminal's serving RAN switching from the source RAN to the target RAN, the access mobility management element receives third indication information from the target RAN. The third indication information is used to instruct the first terminal's serving RAN to switch from the source RAN to the target RAN. The access mobility management element determines first indication information based on the location information of the first terminal and the service area information corresponding to the first terminal. The first indication information is used to indicate whether the first terminal is located within the service area indicated by the service area information. The access mobility management element sends the first indication information to the target RAN or the data management element. The target RAN or the data management element provides the first indication information to the session management element, which manages the session of the first terminal.

[0225] It is understandable that when the session-related functions of the access mobility management network element are decoupled, the session management network element is selected by the source RAN of the terminal. That is, the access mobility management network element does not know the correspondence between the terminal's session and the session management network element, and the access network mobility management network element cannot interact with the session management network element corresponding to the terminal's session.

[0226] In other words, the access mobility management network element (AMF) can respond to the third indication information sent by the target RAN (e.g., carried by handover signaling) and determine whether the first terminal is located within the service area indicated by the service area information based on the location of the first terminal and the service area information corresponding to the first terminal. It then transmits this information (the first indication information) to the target RAN or data management network element. The target RAN or data management network element can then transmit the first indication information to the session management network element, enabling the session management network element to determine which sessions of the first terminal require handover, or to deactivate or release sessions based on the first indication information. Therefore, the solution 3 provided in this application embodiment can reliably manage sessions during handover while decoupling the session-related functions of the AMF.

[0227] It should be understood that with the evolution of the network, Figure 5 The system shown may also support or include other network functions, such as AI or sensing-related functions, which are not specifically limited in this application embodiment.

[0228] Furthermore, with the evolution of networks, the above... Figure 5 The names of the network elements involved may change, but this application does not specifically limit this.

[0229] The following is combined with Figures 7 to 21 The above will be described in detail through method embodiments. Figure 5The diagram illustrates the interaction flow between various network elements / devices in the system. The information transmission method provided in this application can be applied to the above system and specifically to the various scenarios / processes mentioned in the above system.

[0230] The following section will first introduce Option 1.

[0231] Option 1-1:

[0232] Figure 7 This is a flowchart illustrating an information transmission method provided in an embodiment of this application. Figure 1 This information transmission method is applicable to the above. Figure 6 Scheme 1-1, shown in (a) of the diagram, mainly involves the interaction between the source RAN, the target RAN, and the session management network element. For example... Figure 7 As shown, the information transmission method includes the following steps.

[0233] S701. During the process of the first terminal's serving RAN switching from the source RAN to the RAN, the target RAN obtains the service area information corresponding to the first terminal from the source RAN.

[0234] S702, the target RAN determines first indication information based on the location information and service area information of the first terminal. The first indication information indicates whether the first terminal is located within the service area indicated by the service area information.

[0235] S703, the target RAN sends a first indication message to the session management network element. Correspondingly, the session management network element receives the first indication message from the target RAN. The session management network element is used to manage the session of the first terminal.

[0236] S704. The session management network element manages the session of the first terminal according to the first instruction information.

[0237] It is understood that session management can include session switching, session deactivation, or session release. Furthermore, the specific principles by which the session management network element manages the session of the first terminal based on the first instruction information can be found in the aforementioned explanations of steps S203-S208, S305, or S315 in the "Xn Switching" and "N2 Switching" sections, and will not be repeated here.

[0238] Steps S701 to S703 will be explained separately below.

[0239] For step S701:

[0240] In one possible implementation, the service area information includes the SAR information of the first terminal, and / or the service area information of the data network corresponding to the session of the first terminal.

[0241] It is understood that the specific SAR information can be found in the relevant description of SAR in the "2.1 Service Area" section of the preamble of the specific implementation method, and will not be repeated here.

[0242] Additionally, the service area information of the data network corresponding to the session of the first terminal can be found in the relevant description of LADN in "2.1 Service Area". It should be understood that the service area information of the data network in this application embodiment may include the LADN associated with the DN and / or slice network, which will be uniformly stated here and will not be repeated below.

[0243] In other words, the target RAN can obtain the SAR information of the first terminal, and / or the service area information of the data network corresponding to the session of the first terminal, and thus determine whether the first terminal is located in the permitted area indicated by the SAR information, and / or whether the first terminal is located in the service area indicated by the LADN information of the data network corresponding to the session of the first terminal.

[0244] It should be understood that the granularity of the service area indicated by the above service area information can be TA or cell, or RAN granularity. For example, one RAN can correspond to one or more cells, or one or more TAs. This application embodiment does not specifically limit this.

[0245] It is understood that the target RAN obtaining the aforementioned SAR information and / or LADN information from the source RAN specifically refers to the source RAN sending the aforementioned SAR information and / or LADN information to the target RAN. Specifically, the source RAN can obtain the aforementioned SAR information and / or LADN information from the access mobility management network element (AMI). It should be understood that the timing of the source RAN obtaining the aforementioned SAR information and / or LADN information from the AMI is not specifically limited. For example, after the source RAN registers with the NRF, the AMI can send the LADN information corresponding to its supported DN / S-NSSAI to the source RAN; or, after the source RAN sends an N2 message or reports RAN information to the AMI, the AMI sends the SAR information and / or LADN information of the first terminal to the source RAN; or, after the first terminal establishes a PDU session, the AMI can send the SAR information and / or LADN information to the source RAN, or the session management network element can send the LADN information to the source RAN. This application embodiment does not specifically limit this.

[0246] In addition, the source RAN can also be pre-configured for LADN information.

[0247] It is also understood that during the N2 handover process, the target RAN can also obtain the aforementioned SAR information and / or LADN information from the target access mobility management network element. This application embodiment does not specifically limit this.

[0248] For step S702:

[0249] It is understood that the location information of the first terminal can specifically indicate the location of the first terminal, such as the coordinates of the first terminal, or the identifier of the TA and / or cell where the first terminal is located; or it can be indirect indication of the location of the first terminal, such as the identifier of the service area of ​​the target RAN (e.g., the identifier of the TA and / or cell served by the target RAN), or the identifier of the target RAN, etc. For details, please refer to the relevant description in step S201, which will not be repeated here.

[0250] Additionally, the location information of the first terminal can be obtained by the target RAN from the source RAN, for example, during the handover process of Xn, through... Figure 2 In step S201, the source RAN can send the location information of the first terminal to the target RAN; for example, in the handover process of N2, through... Figure 3 In step S307, the target access mobility management network element sends the location information of the first terminal to the target RAN. For example, the target RAN can obtain the location information of the first terminal through other network elements or the first terminal. This application embodiment does not specifically limit this.

[0251] It can also be understood that the target RAN can determine whether the first terminal is located within the service area indicated by the service area information based on the location information of the first terminal and the service area information corresponding to the first terminal (e.g., SAR information and / or LADN information). The specific implementation is similar to... Figure 2 In step S203, the AMF determines whether the UE is located in the permitted area indicated by the SAR information, which is similar to the service area indicated by the LADN information, and will not be described again here.

[0252] For step S703:

[0253] It can be understood that when the target RAN sends the first indication information to the session management network element, it means that the target RAN can obtain the identifier and / or address information of the session management network element, and thus the target RAN can interact with the session management network element directly or indirectly. Here, "the target RAN can interact with the session management network element directly or indirectly" can mean that: the endpoint of the message (or data packet) exchanged between the target RAN and the session management network element is both the target RAN and the session management network element, and there can be an intermediate node between the target RAN and the session management network element that transparently forwards the message; or, there can also be an intermediate node between the target RAN and the session management network element, which is used to redirect the message sent by the target RAN to the session management network element to the session management network element.

[0254] In addition, the target RAN can obtain the identifier and / or address information of the session management network element through the source RAN or through other network elements, such as the target access mobility management network element. This application embodiment does not specifically limit this.

[0255] In one possible implementation, the target RAN specifically sends the first instruction information to the session management network element through the interface between the target RAN and the session management network element.

[0256] It is understandable that there is an interface between the target RAN and the session management network element, and the first indication information is sent by calling the service operations provided by this interface. For example, Figure 4 The distributed NAS architecture shown allows the target RAN to interact directly with the session management network element through a service-oriented interface, thereby avoiding centralized forwarding through the access mobility management network element and decoupling session-related functions in the access mobility management network element.

[0257] In other words, the target RAN sends the first indication information to the session management network element through the interface between the target RAN and the session management network element, which can decouple the session-related functions in the access mobility management network element and thus improve flexibility.

[0258] It is understood that the target RAN can also obtain the session management network element corresponding to each of the multiple sessions of the first terminal from the source RAN or the target access mobility management network element, and then the target RAN can send the first indication information to the session management network element corresponding to each session.

[0259] In addition, depending on the specific content indicated by the first instruction information, the content indicated by the first instruction information may be different for different sessions, as will be explained in detail below.

[0260] In one possible implementation, the first indication information is used to indicate whether the first terminal is located in the permitted area indicated by the SAR information of the first terminal, and / or whether the first terminal is located in the service area indicated by the service area information of the data network corresponding to the session of the first terminal.

[0261] In other words, by instructing the session management network element whether the first terminal is located within the permitted area indicated by the SAR information of the first terminal, the target RAN can enable the session management network element to determine whether to activate or release all non-urgent service sessions of the first terminal based on whether the first terminal is located within the permitted area. Furthermore, by instructing the session management network element corresponding to the i-th session among the multiple sessions of the first terminal whether the first terminal is located within the service area indicated by the service area information (e.g., LADN information) of the data network corresponding to the i-th session, the target RAN can enable the session management network element to determine whether to activate or release the i-th session based on whether the first terminal is located within the service area.

[0262] It should be understood that the target RAN sends the first indication information by switching related signaling, as explained below.

[0263] In one possible implementation, the target RAN sends a first indication message to the session management network element, including: the target RAN sending the first indication message to the session management network element based on the fact that the first terminal is not in the permitted area indicated by the SAR information of the first terminal. The first indication message is used to indicate that the first terminal is not in the permitted area.

[0264] It is understandable that, since the first terminal is not in the permitted area indicated by the SAR information, the first terminal is not allowed to initiate non-emergency services in the service area of ​​the target RAN.

[0265] In other words, the target RAN can send a first indication message to the session management network element to indicate that the first terminal is not in the allowed area indicated by the SAR information of the first terminal, thereby enabling the session management network element to determine that the establishment of a non-urgent service session of the first terminal is not allowed. Thus, in the case of decoupling the session-related functions in the access mobility management network element, reliable session management can be further guaranteed during the handover process.

[0266] In one possible implementation, the target RAN sends a first indication message to the session management network element, including: the target RAN sending a first request to the session management network element. Correspondingly, the session management network element receives the first request from the target RAN. The first request is used to request the deactivation or release of the first terminal's session, and the first request includes the first indication message.

[0267] The session management network element manages the session of the first terminal according to the first instruction information (i.e., step S704), including: the session management network element activates or releases the session of the first terminal according to the first request.

[0268] It is understandable that the first indication information can be explicit or implicit. For example, when the target RAN requests the session management network element to deactivate or confirm the session of the first terminal, it implicitly indicates that the first terminal is not in the allowed area indicated by the SAR information.

[0269] In other words, the target RAN can request the session management network element to activate or release the session of the first terminal, which can implicitly indicate that the first terminal is not in the allowed area indicated by the SAR information, so that the session management network element can activate or release the session of the first terminal according to the request.

[0270] In one possible implementation, the session of the first terminal is a session corresponding to a non-urgent service; the target RAN sends a first request to the session management network element, including: the target RAN sends a first request to the session management network element based on the fact that the session of the first terminal is a session corresponding to a non-urgent service.

[0271] In other words, the target RAN can request the session management network element to activate or release the session corresponding to the non-emergency service of the first terminal, implicitly indicating that the first terminal is not in the permitted area indicated by the SAR information. This allows the session management network element to activate or release the session corresponding to the non-emergency service of the first terminal according to the request, avoiding the activation or release of the session corresponding to the emergency service of the first terminal. Thus, in the case of decoupling the session-related functions in the access mobility management network element, reliable session management can be further guaranteed during the handover process.

[0272] In one possible implementation, the first request includes a first cause value, which indicates that the reason for sending the first request is that the first terminal is not in the permitted area indicated by the SAR information of the first terminal.

[0273] In other words, the reason for activating or releasing the session of the first terminal by indicating the first cause value is that the first terminal is not in the allowed area indicated by the SAR information of the first terminal. This allows the session management network element to avoid trying to establish the session of the first terminal again after deactivating or releasing the session of the first terminal. Thus, in the case of decoupling the session-related functions in the access mobility management network element, it can further ensure that session management can be reliably performed during the handover process.

[0274] In one possible implementation, Figure 7 The method shown also includes:

[0275] S705, the first terminal sends a second indication message to the target RAN. Correspondingly, the target RAN receives the second indication message from the first terminal. The second indication message indicates that the air interface handover is complete.

[0276] S706. The target RAN sends third indication information to the access mobility management network element based on the fact that the first terminal is located within the permitted area indicated by the SAR information of the first terminal. Correspondingly, the access mobility management network element receives the third indication information from the target RAN. The third indication information is used to instruct the first terminal's serving RAN to switch from the source RAN to the target RAN.

[0277] In other words, the target RAN can send a handover-related instruction (i.e., the third instruction) to the access mobility management network element based on the fact that the first terminal is located in the permitted area indicated by the SAR information. This notifies the access mobility management network element that the serving RAN of the first terminal is switching from the source RAN to the target RAN. Thus, the target RAN can send handover-related instructions to the session management network element and the access mobility management network element respectively, thereby decoupling the functions between the SMF and AMF and enhancing flexibility.

[0278] It is understood that step S705 can occur before step S701. Furthermore, there is no timing requirement between step S706 and step S703; for example, step S706 can occur before or after step S703, or both can be executed simultaneously. This application embodiment does not specifically limit this.

[0279] In one possible implementation, the target RAN sends a first indication message to the session management network element, including: the target RAN sending a second request to the session management network element, the second request being used to request the service RAN of the first terminal to be switched from the source RAN to the target RAN, the second request including the first indication message.

[0280] Accordingly, the session management network element manages the session of the first terminal according to the first instruction information (i.e., step S704), including: the session management network element performs session switching on the session of the first terminal according to the second request, the session switching including updating the session management uplink and downlink service RAN of the first terminal from the source RAN to the target RAN.

[0281] It is understood that the second request serves a similar purpose to the session modification request in steps S203, S304, or S314, which is to request the session management network element to update the tunnel information and to notify the corresponding user plane network element. This will not be elaborated further here.

[0282] In addition, when a second request is sent, the first indication information may indicate whether the first terminal is located in the allowed area indicated by the SAR information of the first terminal, and / or whether the first terminal is located in the service area indicated by the service area information of the data network corresponding to the session of the first terminal. This will be explained uniformly here and will not be repeated below.

[0283] In other words, the target RAN can send a second request, including the first indication information, to the session management network element based on whether the first terminal is located in the permitted area indicated by the SAR information. Then, the session management network element can perform session switching, session deactivation, or session release on the first terminal based on whether the first terminal is located in the permitted area indicated by the SAR information and / or whether the first terminal is located in the service area indicated by the service area information of the data network corresponding to the first terminal's session.

[0284] For example, if the first indication information indicates that the first terminal is not in the permitted area indicated by the SAR information, then the session management network element can activate or release the first terminal's session according to the second request. As another example, assuming the first indication information indicates that the first terminal is in the permitted area indicated by the SAR information, but not in the service area indicated by the data network's area information, then the session management network element can activate or release the session corresponding to the first terminal's non-urgent service according to the second request. Yet another example, assuming the first posture information indicates that the first terminal is in the permitted area indicated by the SAR information and is located in the service area indicated by the data network's area information, then the session management network element can switch the session corresponding to the first terminal's non-urgent service according to the second request.

[0285] In this embodiment, the target RAN, by obtaining the service area information corresponding to the first terminal, can determine whether the first terminal is located within the service area indicated by the service area information based on the location information of the first terminal and the service area information. Then, it instructs the session management network element (SMI) through the first indication information. This allows the SMI to determine which sessions of the first terminal need to be switched, or whether sessions need to be deactivated or released. Therefore, the information transmission method provided in this embodiment can reliably manage sessions during the handover process while decoupling the session-related functions of the AMF.

[0286] Furthermore, since the target RAN determines whether the first terminal is located in the service area indicated by the service area information corresponding to the first terminal, after the target RAN sends handover signaling to the access mobility management network element, it does not need to send handover signaling to the session management network element based on the information fed back by the access mobility management network element regarding whether the first terminal is located in the service area. Therefore, the handover signaling sent by the target RAN to the session management network element and the access mobility management network element respectively has no timing requirements, which can better decouple the functions of the access mobility network element and the session management network element and further enhance flexibility.

[0287] Option 1-2:

[0288] It is understandable that the difference between Scheme 1-2 and Scheme 1-1 above is that: during the handover preparation phase of the N2 handover process, the source RAN can send the first indication information to the session management network element so that the session management network element can obtain whether the first terminal is located in the service area indicated by the service information (e.g., SAR information and / or LADN information) corresponding to the first terminal before the handover execution phase.

[0289] Figure 8 This is a flowchart illustrating an information transmission method provided in an embodiment of this application. Figure 2 This information transmission method is applicable to the above. Figure 6 Schemes 1-2 shown in (a) mainly involve the interaction between the source RAN, the target RAN, and the session management network element. For example... Figure 8 As shown, the information transmission method includes the following steps.

[0290] S801, the source RAN obtains the service area information corresponding to the first terminal.

[0291] It is understood that the specific implementation of step S801 can be found in the relevant explanation of the source RAN obtaining service area information in step S701, and will not be repeated here.

[0292] In addition, the service area information includes the service area restriction SAR information of the first terminal, and / or the service area information of the data network corresponding to the session of the first terminal. For details, please refer to the relevant description of step S701, which will not be repeated here.

[0293] S802, during the process of the first terminal's serving RAN switching from the source RAN to the target RAN, the source RAN determines the first indication information based on the first terminal's location information and service area information. The first indication information is used to indicate whether the first terminal is located within the service area indicated by the service area information.

[0294] It is understood that the specific implementation of step S802 can be found in step S702, and will not be repeated here.

[0295] S803, the source RAN sends a first indication message to the session management network element. Correspondingly, the session management network element receives the first indication message from the source RAN. The session management network element is used to manage the session of the first terminal.

[0296] S804. The session management network element manages the session of the first terminal according to the first instruction information.

[0297] It is understandable that the session management network element can specifically manage the session of the first terminal in response to the second request sent by the target RAN during the N2 handover execution phase, based on the first instruction information. This will not be elaborated further here.

[0298] Step S803 will be explained below.

[0299] It is understandable that the source RAN sends the first indication information to the session management network element, which is similar to the target RAN sending the first indication information to the session management network element in the aforementioned step S703. The difference is that the session management network element is selected by the source RAN.

[0300] For example, the source RAN sends the first instruction information to the session management network element through the interface between the source RAN and the session management network element.

[0301] It should be understood that the source RAN can also reuse the above-mentioned first indication information when sending the first indication information to the session management network element. Figure 7 The method shown is related to the implementation of the target RAN sending the first indication information to the session management network element.

[0302] For example, the source RAN sends a first indication message to the session management network element, including: the source RAN sends the first indication message to the session management network element based on the fact that the first terminal is not in the allowed area indicated by the SAR information of the first terminal, and the first indication message is used to indicate that the first terminal is not in the allowed area.

[0303] For example, the source RAN sends a first indication message to the session management network element, which includes: the source RAN sends a third request to the session management network element, the third request being used to request deactivation or release of the session of the first terminal, and the third request including the first indication message.

[0304] For example, the session of the first terminal is a session corresponding to a non-urgent service; the source RAN sends a third request to the session management network element, including: the source RAN sends a third request to the session management network element based on the fact that the session of the first terminal is a session corresponding to a non-urgent service.

[0305] It is understandable that the third request may also include a second reason value. The second reason value is used to indicate that the reason for sending the third request is that the first terminal is not in the allowed area indicated by the SAR information of the first terminal. This can prevent the session management network element from activating or releasing the session of the terminal and then trying to establish the session of the first terminal again.

[0306] For example, the source RAN sends a first indication message to the session management network element, including: the source RAN sending a fourth request to the session management network element, the fourth request being used to request preparation to switch the serving RAN of the first terminal from the source RAN to the target RAN, the fourth request including the first indication message. Accordingly, the session management network element manages the session of the first terminal according to the first indication message (i.e., step S704), including: the session management network element determining whether to modify the user plane network element (e.g., UPF) corresponding to the session of the first terminal according to the fourth request.

[0307] It is understandable that the above modifications affect the user plane network elements corresponding to the session of the first terminal, as can be seen in the aforementioned... Figure 3 The relevant description of step S305 is as follows: For example, in the preparation phase of N2 handover, the SMF can determine whether a new UPF (such as a target UPF or I-UPF) is needed based on the session modification request in step S304 (i.e., the fourth request mentioned above), and modify the tunnel information related to PSA-UPF if it is determined that a new UPF is not needed.

[0308] The above describes the overall method flow for Schemes 1-1 and 1-2. The following section uses Xn switching and N2 switching as examples to further illustrate the above methods. Figure 7 and Figure 8 The method shown will be explained in detail.

[0309] For Xn switching:

[0310] Figure 9 This is a flowchart illustrating an information transmission method provided in an embodiment of this application. Figure 3 .like Figure 9 As shown, this information transmission method is applicable to the above-mentioned Figure 6 Scheme 1-1 shown in (a) mainly involves the terminal (using Figure 9 Taking UE1 as an example), source RAN, target RAN, access mobility management network element (taking UE1 as an example). Figure 9 Taking AMF as an example), session management network element (taking Figure 9 (taking SMF as an example), and user plane network elements (taking...) Figure 9 (Taking UPF as an example) the interaction between them. Additionally, Figure 9 The process shown mainly involves whether UE1 is located in the permitted area indicated by SAR information.

[0311] like Figure 9 As shown, the information transmission method includes the following steps:

[0312] During the registration process of S901 and UE1 with the network, UE1 and the source RAN obtain SAR information.

[0313] It is understandable that when UE1 registers with the network, the AMF determines the SAR information of UE1 during the UE1 registration process and sends the SAR information to the source RAN and UE1.

[0314] S902. Establish a PDU session.

[0315] It is understandable that UE1 can establish a PDU session with the network it registers with. During the process of UE1 establishing a PDU session, the source RAN records the PDU session identifier, the SMF corresponding to the PDU session, and the (temporary) identifier used between UE1 and each SMF. This identifier can be a reused temporary identifier between UE1 and the AMF, i.e., a globally unique temporary UE identity (GUTI).

[0316] S903, RAN handover complete.

[0317] It is understood that the specific implementation of step S903 can be found in step S201 where the RAN handover is completed. For example, the source RAN decides to switch UE1 to the target RAN, and the UE's air interface connection is switched from the source RAN to the target RAN. The target RAN obtains the context information of UE1 from the source RAN through the Xn interface, including the SMF1 / 2 corresponding to session 1 / 2, the UE (temporary) identifier, SAR information, etc., which will not be elaborated here.

[0318] Additionally, after the target RAN receives the UE1 handover completion indication, it triggers steps S904 and S906. It should be understood that steps S904 and S906 have no timing requirements; step S904 can be executed before or after step S906, or both can be executed simultaneously. This application embodiment does not specifically limit this.

[0319] S904. The target RAN sends a first path handover request to the AMF. Accordingly, the AMF receives the first path handover request from the target RAN.

[0320] It is understood that the first path handover request may include: the temporary identifier of UE1, and the TA, and / or the target RAN or cell identifier. Furthermore, the specific implementation of step S904 can be found in [link to relevant documentation]. Figure 7 The relevant descriptions of the third instruction information in the text will not be repeated here.

[0321] S905, the AMF sends a first path handover response to the target RAN. Correspondingly, the target RAN receives the first path handover response from the AMF.

[0322] It is understandable that the first path switching response can be used to indicate that the first path switching request has been received.

[0323] S906. The target RAN sends a second path handover request to the SMF. Accordingly, the SMF receives the second path handover request from the target RAN.

[0324] It is understandable that the target RAN determines whether UE1 is in the allowed area indicated by the SAR information based on UE1's location and UE1's SAR information, that is, whether the TA where UE1 is currently located is in the restricted area.

[0325] Additionally, the second path switching request includes: UE1 (temporary) identifier, PDU session identifier, and information indicating whether UE1 is in the allowed area indicated by SAR information.

[0326] Optionally, the second path switching request may also include the status of the established QoS flow, the identifier and reason for the failed switching PDU session, and the access-side tunnel information corresponding to each PDU session.

[0327] The N4 session modification process is completed between S907, SMF, and UPF.

[0328] It is understood that the specific implementation of step S907 can be found in the aforementioned text. Figure 2 Steps S204 and S205 will not be described in detail here.

[0329] S908, the SMF sends a second path handover response to the target RAN. Correspondingly, the target RAN receives the second path handover response from the SMF.

[0330] Figure 10 This is a flowchart illustrating an information transmission method provided in an embodiment of this application. Figure 4 .like Figure 10 As shown, this information transmission method is similar to Figure 9 The difference between the methods and processes shown is: Figure 10 The process shown mainly involves whether UE1 is located in the service area indicated by the LADN information.

[0331] like Figure 10 As shown, the information transmission method includes the following steps: S1001 to S1009, wherein S1002 to S1006 are the same as steps S901 to S905, and S1008 to S1009 are the same as steps S907 to S908.

[0332] S1001 and AMF send LADN information to the source RAN and / or the target RAN.

[0333] It is understandable that after the RAN (including the source RAN and the target RAN) registers with the NRF, the AMF serving the TA to which the RAN belongs sends the LADN information to the RAN; or, after the RAN sends an N2 message to the AMF to connect to the AMF or report the RAN's information, the AMF sends the LADN information to the RAN; or after UE1 establishes a PDU session, the core network (e.g., AMF, SMF, or other NF) sends the LADN information corresponding to the DN of the PDU session to the RAN; or, it is pre-configured on the RAN.

[0334] S1007. The target RAN sends a second path handover request to the SMF. Correspondingly, the SMF receives the second path handover request from the target RAN.

[0335] It is understandable that the difference between step S1007 and step S906 is that the second path switching request in step S1007 includes: indicating whether UE1 is located in the service area indicated by the LADN information corresponding to UE1's PDU session.

[0336] It should be understood that, since whether the UE is located in the permitted area indicated by the SAR information and whether the UE is located in the service area indicated by the LADN information are two independent judgment factors, Figure 9 and Figure 10 This can be combined, whereby the source RAN determines whether the UE is located in the permitted area indicated by the SAR information, while the target RAN determines whether the UE is located in the service area indicated by the LADN information.

[0337] For N2 switching:

[0338] Figure 11 This is a flowchart illustrating an information transmission method provided in an embodiment of this application. Figure 5 .like Figure 11 As shown, this information transmission method is applicable to the above-mentioned Figure 6 Schemes 1-2 shown in (a) mainly involve terminals (using...) Figure 11 Taking UE1 as an example), source RAN, target RAN, source access mobility management network element (taking UE1 as an example). Figure 11 Taking the source AMF as an example), the target access mobility management network element (taking the source AMF as an example). Figure 11 Taking the target AMF as an example), the session management network element (taking...) Figure 11 Taking SMF as an example, and the interaction between NRF. Additionally, Figure 11 The process shown mainly involves the following: During the preparation phase, the source RAN can send indication information to the SMF to indicate whether UE1 is located in the service area indicated by the LADN information.

[0339] like Figure 11 As shown, the information transmission method includes the following steps:

[0340] S1100: The source RAN obtains the location information of the target RAN from the NRF.

[0341] It is understandable that if the source RAN does not know the location of the target RAN (i.e., the TA corresponding to the target RAN), the source RAN can receive the location of the target RAN from the NRF by sending a query request to the NRF. The query request may include the identifier of the target cell or the target RAN.

[0342] In addition, the source RAN can also be pre-configured with different cell or RAN identifier corresponding to the location (e.g., TA), that is, step S1100 is optional.

[0343] S1101, The source RAN determines whether UE1 is located in the service area indicated by the LADN information.

[0344] Understandably, based on the aforementioned Figure 10 The relevant instructions for step S1001 state that the source RAN can obtain LADN information.

[0345] In addition, when the source RAN decides to hand over UE1 from the source RAN to the target RAN, the source RAN can determine the location of each PDU session on UE1 based on the location of the target RAN or the target cell, and then determine whether UE1 is in the service area indicated by the LADN information corresponding to the session after the handover, that is, whether the TA where UE1 is located after the handover is in the service area indicated by the LADN information.

[0346] S1102, The source RAN sends a handover request to the source AMF. Correspondingly, the source AMF receives the handover request from the source RAN.

[0347] It is understood that the specific implementation of step S1102 can be found in step S301, and will not be repeated here.

[0348] S1103, Source AMF selects target AMF.

[0349] It is understood that the specific implementation of step S1103 can be found in step S302, and will not be repeated here.

[0350] S1104. The source AMF sends a UE context establishment request to the target AMF. Correspondingly, the target AMF receives the UE context establishment request from the source AMF.

[0351] S1105, the source RAN sends a third path handover request to the SMF. Correspondingly, the SMF receives the third path handover request from the source RAN.

[0352] It can be understood that the third path switching request in step S1105 is used to request preparation to switch the serving RAN of UE1 from the source RAN to the target RAN, and the third path switching request includes the indication information indicating whether UE1 is located in the serving area indicated by the LADN information.

[0353] The difference between the content of the third path switching request and the content of the second path switching request in the aforementioned step S1007 is that the third path switching request also includes the identifier of the target RAN.

[0354] It is understood that step S1105 can trigger SMF to perform session management, i.e., the session management in step S305. For example, SMF can determine whether to insert / remove UPF, update session context, etc.

[0355] It should be understood that there is no timing requirement between step S1105 and steps S1102 to S1104. For example, step S1105 can be executed before or after step S1104, or both can be executed simultaneously. This application embodiment does not specifically limit this.

[0356] S1106, the SMF sends a handover indication to the target RAN. Correspondingly, the target RAN receives the handover indication from the SMF. The handover indication includes UPF N3 tunnel information, or a temporary identifier used by the UE between the SMF and the target RAN, etc., which are not specifically limited in this embodiment.

[0357] It is understandable that after the target AMF receives the UE context establishment request in step S1104, the target AMF will send a handover request to the target RAN. For details, please refer to [link to relevant documentation]. Figure 3 Step S307 will not be repeated here.

[0358] Figure 12 This is a flowchart illustrating an information transmission method provided in an embodiment of this application. Figure 6 .like Figure 12 As shown, this information transmission method is similar to Figure 11 The difference between the methods and processes shown is: Figure 12 The process shown mainly involves the target RAN sending indication information to the SMF during the execution phase to indicate whether UE1 is located in the service area indicated by the LADN information.

[0359] like Figure 12 As shown, the information transmission method includes the following steps: S1200 to S1215, wherein step S1200 is the same as step S1100.

[0360] S1201, The source RAN sends a handover request to the source AMF. Correspondingly, the source AMF receives the handover request from the source RAN.

[0361] It is understandable that the difference between step S1201 and step S1102 is that the handover requirement in step S1201 may include LADN information, and thus step S1201 can enable the source AMF to send the LADN information to the target RAN so that the target RAN can determine whether UE1 is located in the service area indicated by the LADN information during the execution phase.

[0362] S1202, Source AMF selects target AMF.

[0363] S1203, the source AMF sends a UE context establishment request to the target AMF. Correspondingly, the target AMF receives the UE context establishment request from the source AMF.

[0364] It should be understood that the UE context establishment request in step S1203 includes LADN information.

[0365] S1204. The source RAN sends a third path handover request to the SMF. Correspondingly, the SMF receives the third path handover request from the source RAN.

[0366] It is understood that the third path switching request in step S1204 does not include the indication information that indicates whether UE1 is located in the service area indicated by the LADN information.

[0367] S1205, the SMF sends a handover instruction to the target RAN. Correspondingly, the target RAN receives the handover instruction from the SMF.

[0368] S1206, The target AMF sends a handover request to the target RAN. Accordingly, the target RAN receives the handover request from the target AMF.

[0369] It is understandable that the switching request in step S1206 is related to... Figure 3 The switching requests in step S307 have similar functions, and will not be described in detail here.

[0370] Additionally, the handover request in step S1206 may include: LADN information, and information for communication between the target AMF and the target RAN.

[0371] S1207. The target RAN sends a handover request confirmation to the target AMF. Correspondingly, the target AMF receives the handover request confirmation from the target RAN.

[0372] The execution phase is described below.

[0373] S1208, the source AMF sends a handover command to the source RAN. Correspondingly, the source RAN receives the handover command from the source AMF.

[0374] It is understandable that the switching command in step S1208 is related to... Figure 3 The handover command in step S312 has the same function, the difference being that the handover command in step S1208 includes a temporary identifier for UE1.

[0375] S1209, The source RAN sends a handover command to UE1. Accordingly, UE1 receives the handover command from the source RAN.

[0376] S1210, RAN handover complete.

[0377] S1211, The target RAN sends a handover notification to the target AMF. Accordingly, the target AMF receives the handover notification from the target RAN.

[0378] It is understandable that the switching notification in step S1211 is related to... Figure 3 The handover notification in step S313 has the same function, except that the handover notification in step S1211 includes a temporary identifier for UE1.

[0379] S1212, The target RAN determines whether UE1 is located in the service area indicated by the LADN information.

[0380] S1213. The target RAN sends a second path handover request to the SMF. Accordingly, the SMF receives the second path handover request from the target RAN.

[0381] It is understood that the specific implementation of step S1213 can be found in step S1007, and will not be repeated here.

[0382] It should be understood that there is no timing requirement between step S1213 and step S1211. For example, step S1214 can be executed before or after step S1211, or both can be executed simultaneously.

[0383] S1214, SMF and UPF complete the N4 session modification process.

[0384] It is understood that the specific implementation of step S1214 can be found in step S907, and will not be repeated here.

[0385] S1215, the SMF sends a second path handover response to the target RAN. Correspondingly, the target RAN receives the second path handover response from the SMF.

[0386] It is understood that the specific implementation of step S1215 can be found in step S908, and will not be repeated here.

[0387] Figure 13This is a flowchart illustrating an information transmission method provided in an embodiment of this application. Figure 7 .like Figure 13 As shown, this information transmission method is similar to the one described above. Figure 11 The method flow shown and Figure 12 The difference between the methods and processes shown is: Figure 13 The method flow shown is used to send indication information to the SMF indicating whether UE1 is located in the allowed area indicated by SAR information.

[0388] like Figure 13 As shown, the information transmission method includes the following steps: S1300 to S1316, wherein step S1300 is the same as step S1100.

[0389] S1301, The source RAN determines whether UE1 is located in the allowed area indicated by the SAR information.

[0390] Understandably, based on the aforementioned Figure 9 The relevant instructions for step S901 state that the source RAN can obtain SAR information.

[0391] In addition, when the source RAN decides to hand over UE1 from the source RAN to the target RAN, the source RAN can determine UE1 based on the location of the target RAN or target cell, and then determine whether UE1 is in the allowed area indicated by the SAR information after the handover, that is, whether the TA where UE1 is located after the handover is in the allowed area indicated by the SAR information.

[0392] S1302, The source RAN sends a handover request to the source AMF. Correspondingly, the source AMF receives the handover request from the source RAN.

[0393] It is understood that the specific implementation of step S1302 can be found in step S301, and will not be repeated here.

[0394] S1303, Source AMF selects target AMF.

[0395] It is understood that the specific implementation of step S1303 can be found in step S302, and will not be repeated here.

[0396] S1304, the source AMF sends a UE context establishment request to the target AMF. Correspondingly, the target AMF receives the UE context establishment request from the source AMF.

[0397] S1305, the source RAN sends a third path handover request to the SMF. Correspondingly, the SMF receives the third path handover request from the source RAN.

[0398] It is understood that the difference between the third path switching request in step S1305 and the third path switching request in step S1105 is that the third path switching request includes the indication information indicating whether UE1 is located in the allowed area indicated by the SAR information.

[0399] It should be understood that there is no timing requirement between step S1305 and steps S1302 to S1304. For example, step S1305 can be executed before or after step S1304, or both can be executed simultaneously. This application embodiment does not specifically limit this.

[0400] S1306, the SMF sends a handover instruction to the target RAN. Correspondingly, the target RAN receives the handover instruction from the SMF.

[0401] It is understood that the switching instruction in step S1306 can be found in the switching instruction in step S1106, and will not be repeated here.

[0402] Figure 14 This is a flowchart illustrating an information transmission method provided in an embodiment of this application. Figure 8 .like Figure 14 As shown, this information transmission method is similar to the one described above. Figure 13 The difference between the methods and processes shown is: Figure 14 In the illustrated process flow, the target RAN sends an indication message to the SMF indicating whether UE1 is located in the permitted area indicated by the SAR information.

[0403] like Figure 14 As shown, the information transmission method includes the following steps: S1400 to S1408, wherein step S1400 is the same as step S1300, and will not be described again here.

[0404] S1401, The source RAN sends a handover request to the source AMF. Correspondingly, the source AMF receives the handover request from the source RAN.

[0405] It is understood that the difference between the handover requirement in step S1401 and the handover requirement in step S1201 is that the handover requirement in step S1401 includes SAR information.

[0406] S1402, Source AMF selects target AMF.

[0407] S1403, the source AMF sends a UE context establishment request to the target AMF. Correspondingly, the target AMF receives the UE context establishment request from the source AMF.

[0408] It should be understood that the UE context establishment request in step S1403 includes SAR information.

[0409] S1404, The target AMF sends a handover request to the target RAN. Accordingly, the target RAN receives the handover request from the target AMF.

[0410] It is understood that the difference between the handover request in step S1404 and the handover request in step S1206 is that the handover request in step S1404 includes SAR information.

[0411] S1405, the target RAN sends a handover request confirmation to the target AMF. Correspondingly, the target AMF receives the handover request confirmation from the target RAN.

[0412] S1406. The target RAN determines whether UE1 is located in the permitted area indicated by the SAR information.

[0413] S1407. The target RAN sends a third path handover request to the SMF. Accordingly, the SMF receives the third path handover request from the target RAN.

[0414] It is understandable that the third path switching request in step S1407 can be found in step S1305, and will not be repeated here.

[0415] S1408, the SMF sends a handover instruction to the target RAN. Accordingly, the target RAN receives the handover instruction from the SMF.

[0416] It is understood that the specific implementation of step S1408 can be found in step S1306, and will not be repeated here.

[0417] It should be understood that the above Figures 11-14 The methods and processes shown can be combined, and the embodiments of this application do not specifically limit this.

[0418] For example, Figure 11 The source RAN sends indication information to the SMF to indicate whether UE1 is located in the service area indicated by the LADN information, which can be combined with Figure 14 The target RAN sends an indication to the SMF whether UE1 is located in the permitted area indicated by the SAR information. For example, Figure 12 During the execution phase, the target RAN sends indication information to the SMF indicating whether UE1 is located in the service area indicated by the LADN information. This information can be combined with... Figure 13 During the preparation phase, the source RAN sends indication information to the SMF to indicate whether UE1 is located in the allowed area indicated by the SAR information.

[0419] Option 2 will be introduced below.

[0420] Figure 15 This is a flowchart illustrating an information transmission method provided in an embodiment of this application. Figure 9 This information transmission method is applicable to the above. Figure 6 Scheme 2, shown in (b) primarily involves the interaction between the source RAN, the target RAN, and the session management network element. For example... Figure 15 As shown, the information transmission method includes the following steps.

[0421] S1501, The session management network element obtains the service area information corresponding to the first terminal.

[0422] It is understandable that the session management network element can obtain service area information from the data management network element or the source RAN in the network; or the session management network element can also pre-configure the service area information corresponding to the first terminal, for example, the session management network element pre-configures the LADN information corresponding to different TAs.

[0423] In addition, as mentioned above Figure 7 The method and process described herein are explained in detail. Service area information may include SAR information and LADN information, which will not be elaborated here.

[0424] S1502, during the process of the serving RAN of the first terminal switching from the source RAN to the target RAN, the source RAN or the target RAN sends a first request to the session management network element. Accordingly, the session management network element receives the first request from the source RAN or the target RAN.

[0425] The first request is used to request a switch of the serving RAN of the first terminal from the source RAN to the target RAN. The first request includes the location information of the first terminal.

[0426] It should be understood that the difference between step S1502 and the aforementioned scheme 1 is that: the SMF can determine whether the first terminal is located in the service area indicated by the service area information based on the location information of the first terminal and the service area information, without requiring the source RAN or the target RAN to send indication information to indicate whether the first terminal is located in the service area indicated by the service area information.

[0427] S1503. The session management network element manages the session of the first terminal based on whether the first terminal is located within the service area indicated by the service area information.

[0428] It is understood that the specific implementation of step S1503 can be found in step S704 or step S804, and will not be repeated here.

[0429] In this embodiment, the session management network element obtains the service area information corresponding to the first terminal. Then, during the handover process from the source RAN to the target RAN, it can respond to a first request sent by the source RAN or the target RAN and determine whether the first terminal is located within the service area indicated by the service area information based on its location information and the service area information. This allows it to determine which sessions of the first terminal need to be switched, or whether sessions need to be deactivated or released. Therefore, the solution 2 provided in this embodiment can reliably manage sessions during the handover process while decoupling the session-related functions of the AMF.

[0430] In addition, since the session management network element can determine whether the first terminal is located in the service area indicated by the service area information corresponding to the first terminal after receiving the first handover request from the target RAN, the handover signaling sent by the target RAN to the session management network element and the access mobility management network element respectively does not have timing requirements. This can better decouple the functions of the access mobility network element and the session management network element, and further enhance flexibility.

[0431] The above describes the overall method and flow corresponding to Scheme 2. The following section uses Xn switching as an example to further illustrate the above... Figure 15 The method shown will be explained in detail.

[0432] Figure 16 This is a flowchart illustrating an information transmission method provided in an embodiment of this application. Figure 10 .like Figure 16 As shown, this information transmission method mainly involves interaction between UE1, source RAN, target RAN, AMF, SMF, and UDM / UDR. Additionally, Figure 16 This involves the SMF determining whether UE1 is located in the permitted area indicated by SAR information.

[0433] like Figure 16 As shown, the information transmission method includes the following steps:

[0434] S1601. Establish a PDU session.

[0435] It is understandable that during the PDU session establishment process of UE1, the source RAN can select the SMF based on the session parameters and send a session establishment request to the SMF.

[0436] Optionally, the source RAN may carry the SAR information of the UE.

[0437] S1601a, The source RAN sends a session establishment request to the SMF. Correspondingly, the SMF receives the session establishment request from the source RAN.

[0438] It is understandable that a session establishment request may include SAR information.

[0439] Additionally, if the SMF does not have SAR information for the UE, the SMF can obtain SAR information from the UDM or UDR.

[0440] Optionally, Figure 16 The method shown also includes:

[0441] S1601b and SMF obtain SAR information of UE1 from UDM or UDR.

[0442] It is understandable that the SMF can obtain the subscription information of UE1 from the UDR, and then request the SAR information in the subscription data of UE1 from the UDM. Alternatively, the SMF can request the SAR information of UE1 from the UDR; or, the SMF can request the SAR information of UE1 from the source RAN; or, after the SMF receives a handover request from the target RAN, it can request the SAR information of UE1 from the target RAN.

[0443] S1602, RAN handover complete.

[0444] It is understood that the specific implementation of step S1602 can be found in step S903, and will not be repeated here.

[0445] In addition, after the target RAN receives the indication information from UE1 indicating that the handover is complete in step S1602, it can trigger the execution of steps S1603 and S1605.

[0446] S1603, The target RAN sends a first path handover request to the AMF. Accordingly, the AMF receives the first path handover request from the target RAN.

[0447] It is understood that the specific implementation of step S1603 can be found in step S904, and will not be repeated here.

[0448] S1604, the AMF sends a first path handover response to the target RAN. Correspondingly, the target RAN receives the first path handover response from the AMF.

[0449] It is understood that the specific implementation of step S1604 can be found in step S905, and will not be repeated here.

[0450] S1605, the target RAN sends a second path handover request to the SMF. Correspondingly, the SMF receives the second path handover request from the target RAN.

[0451] It is understood that step S1605 is similar to step S906, the difference being that the second path switching request in step S1605 does not include indication information used to indicate whether UE1 is located in the allowed area indicated by SAR information.

[0452] Additionally, the second path handover request may include the location information of UE1, such as the cell or identifier of the target RAN, or the TA where UE1 is located.

[0453] S1606 and SMF determine whether UE1 is located in the permitted area indicated by the SAR information based on UE1's location information and SAR information.

[0454] S1607, SMF determines whether to perform a session handover, session deactivation, or session release based on whether UE1 is located in the permitted area indicated by the SAR information.

[0455] S1608, SMF and UPF complete the N4 session modification process.

[0456] S1609, the SMF sends a second path handover response to the target RAN. Correspondingly, the target RAN receives the second path handover response from the SMF.

[0457] Figure 17 This is a flowchart illustrating an information transmission method provided in an embodiment of this application. Figure 10 1. For example Figure 17 As shown, Figure 17 The method and process shown are the same as Figure 16 The difference between the methods shown is that SMF determines whether UE1 is located in the service area indicated by the LADN information.

[0458] like Figure 17 As shown, the information transmission method includes the following steps.

[0459] S1701. Establish a PDU session.

[0460] It is understood that the specific implementation of step S1701 can be found in step S1601, and will not be repeated here.

[0461] S1701a, The source RAN sends a session establishment request to the SMF. Accordingly, the SMF receives the session establishment request from the source RAN.

[0462] It's understandable that SMF can pre-configure LADN information.

[0463] Additionally, if the SMF does not have LADN information, the SMF can request the LADN information of the DN corresponding to the PDU session from the UDR.

[0464] S1702, RAN handover complete.

[0465] It is understood that the specific implementation of step S1702 can be found in step S903, and will not be repeated here.

[0466] In addition, after the target RAN receives the indication information from UE1 indicating that the handover is complete in step S1702, it can trigger the execution of steps S1604 and S1606.

[0467] S1703, The target RAN sends a first path handover request to the AMF. Accordingly, the AMF receives the first path handover request from the target RAN.

[0468] It is understood that the specific implementation of step S1703 can be found in step S904, and will not be repeated here.

[0469] S1704, the AMF sends a first path handover response to the target RAN. Correspondingly, the target RAN receives the first path handover response from the AMF.

[0470] It is understood that the specific implementation of step S1704 can be found in step S905, and will not be repeated here.

[0471] S1705, the target RAN sends a second path handover request to the SMF. Correspondingly, the SMF receives the second path handover request from the target RAN.

[0472] It is understood that step S1705 is similar to step S906, the difference being that the second path switching request in step S1705 does not include indication information for indicating whether UE1 is located in the service area indicated by the LADN information.

[0473] Additionally, the second path handover request may include the location information of UE1, such as the cell or identifier of the target RAN, or the TA where UE1 is located.

[0474] S1706, SMF determines whether UE1 is located in the service area indicated by the LADN information based on UE1's location information and LADN information.

[0475] S1707, SMF determines whether to perform a session handover, session deactivation, or session release based on whether UE1 is located in the service area indicated by the LADN information.

[0476] S1708, SMF and UPF complete the N4 session modification process.

[0477] S1709, the SMF sends a second path handover response to the target RAN. Correspondingly, the target RAN receives the second path handover response from the SMF.

[0478] It is understandable that Scheme 1 and Scheme 2 can be combined. For example, the RAN side can be responsible for determining whether the terminal is located in the allowed area indicated by the SAR information (related to the AMF's policy) and instructing it to the SMF; the SMF can be responsible for determining whether the terminal is located in the service area indicated by the LADN information. This can better decouple the AMF and SMF.

[0479] The following is an exemplary description of the method and process for combining Scheme 1 and Scheme 2.

[0480] Figure 18 This is a schematic flowchart of an information transmission method provided in an embodiment of this application. Figure 10 2. For example Figure 18 As shown, this information method is illustrated using Xn handover as an example, mainly involving the interaction between UE1, source RAN, target RAN, AMF, SMF, and UPF.

[0481] like Figure 18 As shown, the information transmission method includes the following steps.

[0482] During the S1801 and UE1 registration process with the network, UE1 and the source RAN acquire SAR information.

[0483] It is understood that the specific implementation of step S1801 can be found in step S901, and will not be repeated here.

[0484] S1802. Establish a PDU session.

[0485] It is understood that the specific implementation of step S1802 can be found in step S902, and will not be repeated here.

[0486] S1803, RAN handover complete.

[0487] It is understood that the specific implementation of step S1803 can be found in step S903, and will not be repeated here.

[0488] S1804, the target RAN sends a first path handover request to the AMF. Correspondingly, the AMF receives the first path handover request from the target RAN.

[0489] It is understood that the specific implementation of step S1804 can be found in step S904, and will not be repeated here.

[0490] S1805, the AMF sends a first path handover response to the target RAN. Accordingly, the target RAN receives the first path handover response from the AMF.

[0491] It is understood that the specific implementation of step S1805 can be found in step S905, and will not be repeated here.

[0492] S1806, The target RAN sends a second path handover request to the SMF. Accordingly, the SMF receives the second path handover request from the target RAN.

[0493] It should be understood that step S1806 and step S906 may be the same, or step S1806 may also include LADN information for SMF to determine whether UE1 is located in the service area indicated by the LADN information.

[0494] S1807, SMF determines whether UE1 is located in the service area indicated by the LADN information based on UE1's location information and LADN information.

[0495] S1808, SMF determines whether to perform a session handover, or to deactivate or release a session based on the second path handover request indicating whether UE1 is in the allowed area indicated by SAR information and whether UE1 is in the service area indicated by LADN information.

[0496] S1809, SMF and UPF complete the N4 session modification process.

[0497] S1810, the SMF sends a second path handover response to the target RAN. Correspondingly, the target RAN receives the second path handover response from the SMF.

[0498] Option 3 will be introduced below.

[0499] Figure 19 This is a flowchart illustrating an information transmission method provided in an embodiment of this application. Figure 10 III. This information transmission method applies to the above-mentioned... Figure 6 Scheme 3, shown in (c), mainly involves the interaction between the source RAN, the target RAN, and the session management network element. For example... Figure 19 As shown, the information transmission method includes the following steps.

[0500] S1901, during the process of the serving RAN of the first terminal switching from the source RAN to the target RAN, the target RAN sends third indication information to the access mobility management element. Correspondingly, the access mobility management element receives the third indication information from the target RAN.

[0501] The third instruction information is used to instruct the first terminal to switch its serving RAN from the source RAN to the target RAN.

[0502] It is understood that the specific implementation of step S1901 can be found in step S706, and will not be repeated here.

[0503] S1902. The access mobility management network element determines the first indication information based on the location information of the first terminal and the service area information corresponding to the first terminal. The first indication information is used to indicate whether the first terminal is located within the service area indicated by the service area information.

[0504] It is understood that the specific implementation of step S1902 can be found in step S702 or step S802, and will not be repeated here.

[0505] S1903. The access mobility management network element sends a first indication message to the target RAN or data management network element. Correspondingly, the target RAN or data management network element receives the first indication message from the access mobility management network element.

[0506] The target RAN or data management network element is used to provide first instruction information to the session management network element, which is used to manage the session of the first terminal.

[0507] It is understandable that data management network elements could be, for example, Figure 1 The UDM or UDR in this application embodiment is not specifically limited in this respect.

[0508] It should be understood that the target RAN may send the first indication information to the session management network element during the handover process of the first terminal. Alternatively, when the session management network element receives a handover request from the source RAN or the target RAN, the session management network element may obtain the first indication information from the data management network element. This application embodiment does not specifically limit this.

[0509] In this embodiment, the Access Mobility Management (AMF) element can respond to the third indication information sent by the target RAN (e.g., carried by handover signaling) and determine whether the first terminal is located within the service area indicated by the service area information based on the location of the first terminal and the service area information corresponding to the first terminal. It then transmits this information (the first indication information) to the target RAN or the Data Management (DMF) element. The target RAN or DMF element can then transmit the first indication information to the Session Management (SMU) element, enabling the SMU to determine which sessions of the first terminal require handover, or to deactivate or release sessions based on the first indication information. Therefore, the solution 3 provided in this embodiment can reliably manage sessions during handover while decoupling the AMF's session-related functions.

[0510] The following example uses Xn switching to illustrate... Figure 19 The method and flow shown will be further explained.

[0511] Figure 20 This is a schematic flowchart of an information transmission method provided in an embodiment of this application. Figure 10 IV. For example Figure 20As shown, the information transmission method flow is similar to Figure 9 The method flow shown is similar, the difference being that: the information cells included in the first path handover response sent by the AMF to the target RAN can indicate whether UE1 is located in the allowed area indicated by the SAR information, and / or whether UE1 is located in the service area indicated by the LADN information.

[0512] like Figure 20 As shown, the information transmission method includes the following steps: S2001 to S2008, S2001 to S2004 are the same as steps S901 to S904, and S2006 to S2008 are the same as steps S906 to S908, which will not be repeated here.

[0513] S2005, the AMF sends a first path handover response to the target RAN. Correspondingly, the target RAN receives the first path handover response from the AMF.

[0514] The first path switching response includes first indication information, which indicates whether UE1 is located in the allowed area indicated by SAR information, and / or whether UE1 is located in the service area indicated by LADN information.

[0515] Figure 21 This is a schematic flowchart of an information transmission method provided in an embodiment of this application. Figure 10 5. For example Figure 21 As shown, this information transmission method is similar to Figure 20 The difference in the method flow shown is that after the AMF determines the first indication information, it sends the first indication information to the UDR, which enables the SMF to obtain the first indication information from the UDR.

[0516] like Figure 21 As shown, the information transmission method includes the following steps: S2101 to S2109. S2101 to S2103 are the same as steps S2002 to S2004, and will not be described again here.

[0517] S2104, AMF sends the first indication information to UDR. Correspondingly, UDR receives the first indication information from AMF.

[0518] It is understood that the AMF can determine the first indication information, i.e., whether UE1 is located in the permitted area indicated by the SAR information, and / or whether UE1 is located in the service area indicated by the LADN information, based on the location information of UE1 included in the first path switching request.

[0519] S2105, the AMF sends a first path handover response to the target RAN. Correspondingly, the target RAN receives the first path handover response from the AMF.

[0520] S2106. The target RAN sends a second path handover request to the SMF. Accordingly, the SMF receives the second path handover request from the target RAN.

[0521] It should be understood that the second path switching request in step S2106 may not include UE1's location information and / or, service area information (e.g., SAR information and / or LADN information).

[0522] S2107, SMF obtains the first instruction information from UDR.

[0523] It is understandable that the SMF can subscribe to the status of UE1 in the service area from the UDR, and thus obtain the first indication information when the location of UE1 changes. In addition, if the status of UE1 in the service area does not change, the SMF can determine whether to perform a session handover, or session deactivation or release, based on whether UE1 is located in the allowed area indicated by the SAR information and / or whether UE1 is located in the service area indicated by the LADN information, which were previously subscribed to.

[0524] Optionally, step S2107 includes:

[0525] S2107a, the SMF sends a subscription request to the UDR. Correspondingly, the UDR receives the subscription request from the SMF. The subscription request is used to subscribe to the status of U1 in the service area.

[0526] S2107b: When the status of UE1 in the serving area changes, the UDR sends a notification message to the SMF. Correspondingly, the SMF receives the notification message from the UDR. The notification message includes first indication information.

[0527] Alternatively, step S2107 may include:

[0528] In response to the second path switching request, S2107c and SMF send a query request to UDR. Correspondingly, UDR receives the query request from SMF.

[0529] S2107d, UDR sends a query response to SMF. Correspondingly, SMF receives the query response from UDR. The query response includes first indication information.

[0530] It is understandable that the SMF can send a query request to the UDR to query the status of UE1 in the service area and thus obtain the first indication information.

[0531] S2108, SMF completes the N4 session modification process with UPF based on the first instruction information.

[0532] S2109, the SMF sends a second path handover response to the target RAN. Correspondingly, the target RAN receives the second path handover response from the SMF.

[0533] The above mainly describes the solutions provided by the embodiments of this application from the perspective of interaction between various network elements. Correspondingly, the embodiments of this application also provide a communication device for implementing the various methods described above. This communication device can be the target RAN, source RAN, session management network element, or access mobility management network element in the above method embodiments, or a device containing the aforementioned target RAN, source RAN, session management network element, or access mobility management network element, or a component usable in the target RAN, source RAN, session management network element, or access mobility management network element. It is understood that, in order to achieve the above functions, the communication device includes 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, 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.

[0534] This application embodiment can divide the communication device into functional modules according to the above method embodiment. For example, each function can be divided into a separate functional module, or two or more functions can be integrated into one processing module. The integrated module can be implemented in hardware or as a software functional module. It should be noted that the module division in this application embodiment is illustrative and only represents one logical functional division. In actual implementation, there may be other division methods.

[0535] Taking the communication device as an example, which is the target RAN, source RAN, session management network element, or access mobility management network element in the above method embodiments, Figure 22 This is a schematic diagram of the structure of a communication device provided in an embodiment of this application. Figure 22 As shown, the communication device 2200 includes a processing module 2201 and a transceiver module 2202. The processing module 2201 is used to perform the processing functions of the target RAN, source RAN, session management network element, or access mobility management network element in the above method embodiments. The transceiver module 2202 is used to perform the transceiver functions of the target RAN, source RAN, session management network element, or access mobility management network element in the above method embodiments.

[0536] All relevant content of each step involved in the above method embodiments can be referenced from the functional description of the corresponding functional module, and will not be repeated here.

[0537] Since the communication device 2200 provided in this embodiment can execute the above information transmission method, the technical effects it can achieve can be referred to the above method embodiment, and will not be repeated here.

[0538] In one possible design, the transceiver module 2202 may include a receiving module and a transmitting module. Figure 22 (Not shown in the image). The transceiver module is used to implement the sending and receiving functions of the communication device 2200.

[0539] In one possible design, the communication device 2200 may further include a storage module. Figure 22 (Not shown in the image), this storage module stores programs or instructions. When the processing module 2201 executes the program or instructions, it enables the communication device 2200 to perform operations. Figures 7 to 21 The functions of the target RAN, source RAN, session management network element, or access mobility management network element in any of the methods shown.

[0540] It should be understood that the processing module 2201 involved in the communication device 2200 can be implemented by a processor or processor-related circuit components, and can be a processor or processing unit; the transceiver module 2202 can be implemented by a transceiver or transceiver-related circuit components, and can be a transceiver or transceiver unit.

[0541] For example, Figure 23 This is a schematic diagram of another communication device provided in an embodiment of this application. The communication device can be a target RAN, a source RAN, a session management network element, or an access mobility management network element, or it can be a chip (system) or other component or assembly that can be disposed in the target RAN, source RAN, session management network element, or access mobility management network element. Figure 23 As shown, the communication device 2300 may include a processor 2301. In one possible design, the communication device 2300 may further include a memory 2302 and / or a transceiver 2303. The processor 2301 is coupled to the memory 2302 and the transceiver 2303, for example, they can be connected via a communication bus.

[0542] The following is combined Figure 23 A detailed description of each component of the communication device 2300 is provided below:

[0543] The processor 2301 is the control center of the communication device 2300. It can be a single processor or a collective term for multiple processing elements. For example, the processor 2301 can be one or more central processing units (CPUs), application-specific integrated circuits (ASICs), or one or more integrated circuits configured to implement the embodiments of this application, such as one or more digital signal processors (DSPs), or one or more field-programmable gate arrays (FPGAs).

[0544] In one possible design, the processor 2301 can perform various functions of the communication device 2300 by running or executing software programs stored in the memory 2302 and calling data stored in the memory 2302.

[0545] In a specific implementation, as one example, the processor 2301 may include one or more CPUs, for example... Figure 23 CPU0 and CPU1 are shown in the diagram.

[0546] In a specific implementation, as one example, the communication device 2300 may also include multiple processors, for example... Figure 23 The processors 2301 and 2304 are shown. Each of these processors can be a single-core processor or a multi-core processor. Here, "processor" can refer to one or more devices, circuits, and / or processing cores used to process data (e.g., computer program instructions).

[0547] The memory 2302 is used to store the software program that executes the solution of this application, and is controlled by the processor 2301 to execute it. The specific implementation method can be referred to the above method embodiment, and will not be repeated here.

[0548] In one possible design, the memory 2302 can be a read-only memory (ROM) or other type of static storage device capable of storing static information and instructions, random access memory (RAM) or other type of dynamic storage device capable of storing information and instructions, or it can be an electrically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM) or other optical disc storage, optical disc storage (including compressed optical discs, laser discs, optical discs, digital universal optical discs, Blu-ray discs, etc.), 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, but is not limited thereto. The memory 2302 can be integrated with the processor 2301 or exist independently and coupled to the processor 2301; this application embodiment does not specifically limit this.

[0549] Transceiver 2303 is used for communication with other communication devices. For example, if communication device 2300 is the target RAN, transceiver 2303 can be used to communicate with the source RAN or session management network element. As another example, if communication device 2300 is the source RAN, transceiver 2303 can be used to communicate with the target RAN or session management network element.

[0550] In one possible design, transceiver 2303 may include a receiver and a transmitter. Figure 23 (Not shown separately). The receiver is used to implement the receiving function, and the transmitter is used to implement the sending function.

[0551] In one possible design, the transceiver 2303 can be an input / output interface or interface circuit for inputting and / or outputting signals.

[0552] In one possible design, the transceiver 2303 can be integrated with the processor 2301, or it can exist independently and be coupled to the processor 2301. This application embodiment does not specifically limit this.

[0553] It should be noted that, Figure 23 The structure of the communication device 2300 shown does not constitute a limitation on the communication device. Actual communication devices may include more or fewer components than shown, or combine certain components, or have different component arrangements.

[0554] Furthermore, the communication device 2300 can execute the above-described information transmission method, and therefore the technical effects it can achieve can be referred to the above-described method embodiments, which will not be repeated here.

[0555] In one possible implementation, this application also provides a computer-readable storage medium storing a computer program or instructions that, when executed by a computer, implement the functions of the above-described method embodiments.

[0556] In one possible implementation, this application also provides a computer program product that, when executed by a computer, implements the functions of the above-described method embodiments.

[0557] In one possible implementation, this application embodiment also provides a communication system, which includes the target RAN and session management network element described in the above method embodiments, or the communication system includes the source RAN and session management network element described in the above method embodiments, the access mobility management network element described in the above method embodiments, and the target RAN and / or data management network element.

[0558] In one possible implementation, this application also provides a communication method, which includes the method described in any of the above-described method embodiments or any implementation thereof.

[0559] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented using software programs, implementation can be, in whole or in part, in the form of a computer program product. This computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the flow or function according to the embodiments of this application is generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium accessible to a computer or a data storage device including one or more servers, data centers, etc., that can be integrated with the medium. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium, or a semiconductor medium (e.g., a solid-state drive (SSD)).

[0560] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software 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.

[0561] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0562] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0563] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0564] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0565] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0566] Although this application has been described herein in conjunction with various embodiments, those skilled in the art, by reviewing the accompanying drawings, the disclosure, and the appended claims, will understand and implement other variations of the disclosed embodiments in carrying out the claimed application. In the claims, the word "comprising" does not exclude other components or steps, and "a" or "an" does not exclude multiple instances. A single processor or other unit can implement several functions listed in the claims. While different dependent claims may recite certain measures, this does not mean that these measures cannot be combined to produce good results.

[0567] Although this application has been described in conjunction with specific features and embodiments, it is obvious that various modifications and combinations can be made thereto without departing from the scope of this application. Accordingly, this specification and drawings are merely exemplary illustrations of the application as defined by the appended claims, and are considered to cover any and all modifications, variations, combinations, or equivalents within the scope of this application. Clearly, those skilled in the art can make various alterations and modifications to this application without departing from its scope. Thus, if such modifications and modifications fall within the scope of the claims and their equivalents, this application is also intended to include such modifications and modifications.

Claims

1. A method of information transmission, characterized in that, The method comprises: In a process of switching a serving radio access network of a first terminal from a source radio access network to a target radio access network, the target radio access network acquires service area information corresponding to the first terminal from the source radio access network; The target radio access network determines first indication information according to location information of the first terminal and the service area information, the first indication information being used to indicate whether the first terminal is located in a service area indicated by the service area information; The target radio access network sends the first indication information to a session management network element, the session management network element being used to manage a session of the first terminal.

2. The method of claim 1, wherein, The target radio access network specifically sends the first indication information to the session management network element through an interface between the target radio access network and the session management network element.

3. The method according to claim 1 or 2, characterized in that, The target radio access network sends the first indication information to a session management network element, comprising: The target radio access network sends the first indication information to the session management network element according to that the first terminal is not located in an allowed area indicated by service area restriction information of the first terminal, the first indication information being used to indicate that the first terminal is not located in the allowed area.

4. The method of claim 3, wherein, The target radio access network sends the first indication information to a session management network element, comprising: The target radio access network sends a first request to the session management network element, the first request being used to request to deactivate or release a session of the first terminal, the first request comprising the first indication information.

5. The method according to any one of claims 1-4, characterized in that, The target radio access network sends the first indication information to a session management network element, comprising: The target radio access network sends a second request to the session management network element, the second request being used to request to switch a serving radio access network of the first terminal from the source radio access network to the target radio access network, the second request comprising the first indication information.

6. An information transmission method characterized by comprising: The method comprises: A source radio access network acquires service area information corresponding to a first terminal; In a process of switching a serving radio access network of the first terminal from the source radio access network to a target radio access network, the source radio access network determines first indication information according to location information of the first terminal and the service area information, the first indication information being used to indicate whether the first terminal is located in a service area indicated by the service area information; The source radio access network sends the first indication information to a session management network element, the session management network element being used to manage a session of the first terminal.

7. The method of claim 6, wherein, The source radio access network specifically sends the first indication information to the session management network element through an interface between the source radio access network and the session management network element.

8. An information transmission method characterized by comprising: The method comprises: In a process of switching a serving radio access network of a first terminal from a source radio access network to a target radio access network, a session management network element receives first indication information from the target radio access network or the source radio access network, the first indication information being used to indicate whether the first terminal is located in a service area indicated by the service area information; The session management network element manages a session of the first terminal according to the first indication information.

9. The method according to any one of claims 1-8, characterized in that, The service area information includes service area restriction information of the first terminal, and / or service area information of a data network corresponding to a session of the first terminal.

10. The method according to any one of claims 1-9, characterized in that, The first indication information is used for indicating whether the first terminal is located in an allowed area indicated by the service area restriction information of the first terminal, and / or whether the first terminal is located in a service area indicated by the service area information of a data network corresponding to a session of the first terminal.

11. A communications device, characterized by The communication apparatus includes a module or unit for performing the method of any one of claims 1-10.

12. A communications device, characterized by The communication apparatus includes at least one processor configured to cause the communication apparatus to perform the method of any one of claims 1-10 by logic circuitry and / or executing instructions.

13. A computer-readable storage medium, characterized in that, The computer readable storage medium includes instructions that, when executed, cause the method of any one of claims 1-10 to be implemented.

14. A computer program product, characterised in that, The computer program product includes instructions that, when executed, cause the method of any one of claims 1-10 to be implemented.

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