Information transmission method and communication apparatus

Abstract

Provided in the embodiments of the present application are an information transmission method and a communication apparatus, which can ensure that session management can be reliably performed during the switching of a terminal when a session-related function is decoupled from an access and mobility management network element. The method comprises: during 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 acquiring, from the source radio access network, service area information corresponding to the first terminal; the target radio access network determining first indication information on the basis of location information and the service area information of the first terminal, wherein the first indication information is used for indicating whether the first terminal is located in a service area indicated by the service area information; and the target radio access network sending the first indication information to a session management network element, wherein the session management network element is used for managing a session of the first terminal.

Description

Information transmission method and communication device

[0001] The present application claims priority from the Chinese patent application No. 202410878826.1 filed on June 30, 2024, and entitled "Information transmission method and communication device", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present application relates to the field of communication, in particular to an information transmission method and a communication device. BACKGROUND

[0003] In the research of future communication network, decoupling the access and mobility management function (AMF) about session related function can improve the flexibility of the communication network and better meet the needs of new services.

[0004] However, how to ensure that the session management can be reliably performed in the handover process under the condition of decoupling the AMF about the session related function is a research hotspot at present. SUMMARY

[0005] The information transmission method and the communication device provided by the embodiments of the present application can ensure that the session management can be reliably performed in the terminal handover process under the condition of decoupling the AMF about the session related function.

[0006] To achieve the above-mentioned purpose, the embodiments of the present application adopt the following technical solutions:

[0007] In a first aspect, an information transmission method is provided, the method comprising: in a process of a serving RAN of a first terminal switching from a source RAN to a target radio access network (RAN), the target RAN acquiring service area information corresponding to the first terminal from the source RAN; the target RAN determining 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; and the target RAN sending 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.

[0008] Since in the embodiment of the present application, the target RAN can determine whether the first terminal is located in the service area indicated by the service area information corresponding to the first terminal according to the location information of the first terminal and the service area information, and then indicate to the session management network element through the first indication information, the session management network element can determine which session of the first terminal needs to be switched, or deactivated or released according to the first indication information. Therefore, the information transmission method provided by the embodiment of the present application can guarantee reliable session management in the handover process in the case of decoupling the session-related functions of the AMF.

[0009] In addition, 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, and then sends the signaling related to the handover to the access mobility management network element, it is not necessary to send the signaling related to the handover to the session management network element based on the information fed back by the access mobility management network element about whether the first terminal is located in the service area, so that the signaling related to the handover sent by the target RAN to the session management network element and the access mobility management network element respectively has no timing requirement, which can better decouple the functions of the access mobility network element and the session management network element, and further enhance flexibility.

[0010] In a possible implementation, the target RAN specifically sends the first indication information to the session management network element through an interface between the target RAN and the session management network element. That is, 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 further improve flexibility.

[0011] In a possible implementation, the service area information includes service area restriction (SAR) information of the first terminal, and / or service area information of a 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 then determine whether the first terminal is located in the allowed 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.

[0012] In a possible implementation, the first indication information is used to 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. That is, the target RAN can make the session management network element determine whether to deactivate or release all non-emergency service sessions of the first terminal according to whether the first terminal is located in the allowed area indicated by the SAR information of the first terminal by indicating to the session management network element whether the first terminal is located in the allowed area. In addition, the target RAN can make the session management network element determine whether to deactivate or release the i th session of the first terminal according to whether the first terminal is located in the service area indicated by the service area information (for example, LADN information) of the data network corresponding to the i th session by indicating to the session management network element corresponding to the i th session of the first terminal whether the first terminal is located in the service area.

[0013] In a possible implementation, the target RAN sends the first indication information to the session management network element, including: the target RAN sends the first indication information to the session management network element according to that the first terminal is not located in the allowed area indicated by the SAR information of the first terminal, and the first indication information is used to indicate that the first terminal is not located in the allowed area. That is, the target RAN can send the first indication information to the session management network element to indicate that the first terminal is not located in the allowed area according to that the first terminal is not located in the allowed area indicated by the SAR information of the first terminal, and then the session management network element can be made to determine that the non-emergency service session of the first terminal is not allowed to be established, so that the session management can be reliably performed in the handover process when the session-related function in the decoupled access mobility management network element is further guaranteed.

[0014] In a possible implementation, the target RAN sends the first indication information to the session management network element, including: the target RAN sends a first request to the session management network element, the first request is used to request to deactivate or release the session of the first terminal, and the first request includes the first indication information. That is, the target RAN can implicitly indicate that the first terminal is not located in the allowed area indicated by the SAR information by requesting the session management network element to deactivate or release the session of the first terminal, and then the session management network element can deactivate or release the session of the first terminal according to the request.

[0015] In a possible implementation, the session of the first terminal is a session corresponding to non-urgent service; and the target RAN sends the first request to the session management network element, including: the target RAN sends the first request to the session management network element according to the session of the first terminal being the session corresponding to non-urgent service. That is, the target RAN can implicitly indicate that the first terminal is not in the allowed area indicated by the SAR information by requesting the session management network element to deactivate or release the session of the first terminal corresponding to non-urgent service, so that the session management network element can deactivate or release the session of the first terminal corresponding to non-urgent service according to the request, and avoid deactivating or releasing the session of the first terminal corresponding to urgent service, thereby further guaranteeing that the session management can be reliably performed in the handover process in the case that the session-related function of the access mobility management network element is decoupled.

[0016] In a possible implementation, the first request includes a first reason value, and the first reason value is used to indicate that the reason for sending the first request is that the first terminal is not in the allowed area indicated by the SAR information of the first terminal. That is, by indicating that the reason for deactivating or releasing the session of the first terminal is that the first terminal is not in the allowed area indicated by the SAR information of the first terminal, the session management network element can avoid attempting to establish the session of the first terminal again after deactivating or releasing the session of the first terminal, thereby further guaranteeing that the session management can be reliably performed in the handover process in the case that the session-related function of the access mobility management network element is decoupled.

[0017] In a possible implementation, the method provided in the first aspect further includes: the target RAN receives second indication information from the first terminal, the second indication information being used to indicate that the air interface handover is completed; and the target RAN sends third indication information to the access mobility management network element according to the first terminal being located in the allowed area indicated by the SAR information of the first terminal, wherein the third indication information is used to indicate that the serving RAN of the first terminal is switched from the source RAN to the target RAN. That is, the target RAN can send the handover-related indication (i.e., the third indication) to the access mobility management network element according to the first terminal being located in the allowed area indicated by the SAR information, thereby notifying the access mobility management network element that the serving RAN of the first terminal is switched from the source RAN to the target RAN, so that the target RAN can send the handover-related indication to the session management network element and the access mobility management network element respectively, realize the decoupling of the functions between the SMF and the AMF, and enhance flexibility.

[0018] In a possible implementation, the target RAN sends the first indication information to the session management network element, including: the target RAN sends a second request to the session management network element, the second request being used for requesting to switch the service RAN of the first terminal from the source RAN to the target RAN, and the second request including the first indication information. That is, the target RAN can send the second request including the first indication information to the session management network element according to that the first terminal is located in the allowed area indicated by the SAR information, and then the session management network element can perform session switching, or session deactivation or release on the session of the first terminal according to whether the first terminal is located in the allowed 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 session of the first terminal.

[0019] In a second aspect, an information transmission method is provided, including: a source radio access network (RAN) acquires service area information corresponding to a first terminal; in a process of switching a service RAN of the first terminal from a source RAN to a target RAN, the source RAN determines first indication information according to location 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 source RAN sends the first indication information to a session management network element, the session management network element being used for managing a session of the first terminal.

[0020] In a possible implementation, the source RAN sends the first indication information to the session management network element through an interface between the source RAN and the session management network element.

[0021] In a possible implementation, the service area information includes service area restriction (SAR) information of the first terminal, and / or service area information of a data network corresponding to the session of the first terminal.

[0022] In a possible implementation, the first indication information is used for indicating: whether the first terminal is located in an 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.

[0023] In a possible implementation, the source RAN sends the first indication information to the session management network element, including: the source RAN sends the first indication information to the session management network element according to that the first terminal is not located in the allowed area indicated by the SAR information of the first terminal, the first indication information being used for indicating that the first terminal is not located in the allowed area.

[0024] In a possible implementation, the source RAN sends the first indication information 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 for requesting to deactivate or release the session of the first terminal, and the third request including the first indication information.

[0025] In a possible implementation, the session of the first terminal is a session corresponding to non-urgent service; and the source RAN sends the third request to the session management network element, including: the source RAN sends the third request to the session management network element according to that the session of the first terminal is a session corresponding to non-urgent service.

[0026] In a possible implementation, the third request includes a second cause value, and the second cause 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.

[0027] In a possible implementation, the source RAN sends the first indication information to the session management network element, including: the source RAN sends a fourth request to the session management network element, and the fourth request is used to request to prepare to switch the serving RAN of the first terminal from the source RAN to the target RAN, and the fourth request includes the first indication information.

[0028] The beneficial effects brought by the second aspect and any implementation thereof can be specifically referred to the beneficial effects corresponding to the first aspect and any implementation thereof, which will not be repeated here.

[0029] The third aspect provides an information transmission method, including: in the process of switching the serving radio access network (RAN) of a first terminal 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, and the first indication information is used to indicate whether the first terminal is located in a service area indicated by service area information; and the session management network element manages a session of the first terminal according to the first indication information.

[0030] In a possible implementation, the session management network element receives the first indication information from the target RAN through an interface between the target RAN and the session management network element; or the session management network element receives the first indication information from the source RAN through an interface between the source RAN and the session management network element.

[0031] In a possible implementation, the service area information includes service area restriction (SAR) information of the first terminal, and / or service area information of a data network corresponding to the session of the first terminal.

[0032] In a possible implementation, the first indication information is used to indicate whether the first terminal is located in an allowed area indicated by the SAR information of the first terminal, and / or whether the first terminal is located in a service area indicated by service area information of a data network corresponding to the session of the first terminal.

[0033] In a possible implementation, the first indication information is specifically used for indicating that the first terminal is not in the allowed 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 the first request from the target RAN or the third request from the source RAN, the first request or the third request is used for requesting to deactivate or release the session of the first terminal, and the first request or the third request includes 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 deactivates or releases the session of the first terminal according to the first request or the third request.

[0034] In a possible implementation, the session management network element receives the first indication information from the target RAN, including: the session management network element receives the second request from the target RAN, the second request is used for requesting to switch the serving RAN of the first terminal from the source RAN to the target RAN, and the second request includes 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, and the session switching includes updating the serving RAN in the session management context of the first terminal from the source RAN to the target RAN.

[0035] In a possible implementation, the session management network element receives the first indication information from the source RAN, including: the session management network element receives the fourth request from the source RAN, the fourth request is used for requesting to prepare to switch the serving RAN of the first terminal from the source RAN to the target RAN, and the fourth request includes 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.

[0036] In a possible implementation, 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 the first request from the target RAN or the third request from the source RAN, the first request or the third request is used for requesting to switch the serving RAN of the first terminal from the source RAN to the target RAN, and the first request or the third request includes 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 deactivates or releases the session of the first terminal according to the first request or the third request.

[0037] In the embodiment of the present application, the session management network element acquires the service area information corresponding to the first terminal, and then in the process of switching the service RAN of the first terminal from the source RAN to the target RAN, the session management network element can determine whether the first terminal is located in the service area indicated by the service area information according to the location information of the first terminal and the service area information in response to the first request sent by the source RAN or the target RAN, so as to determine which sessions of the first terminal need to be switched, or deactivated or released. Therefore, the scheme 2 provided in the embodiment of the present application can guarantee reliable session management in the process of switching in the case of decoupling the session-related functions of the AMF.

[0038] 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 request about switching from the target RAN, the signaling about switching sent by the target RAN to the session management network element and the access mobile management network element has no timing requirement, so that the functions of the access mobile network element and the session management network element can be better decoupled, and the flexibility is further enhanced.

[0039] In a fifth aspect, an information transmission method is provided, which includes: in the process of switching the service RAN of the first terminal from the source RAN to the target RAN, the access mobile management network element receives third indication information from the target RAN, the third indication information being used to indicate that the service RAN of the first terminal is switched from the source RAN to the target RAN; the access mobile management network element determines first indication information according to 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 in the service area indicated by the service area information; and the access mobile management network element sends the first indication information to the target RAN or the data management network element, the target RAN or the data management network element being used to provide the first indication information to the session management network element, and the session management network element being used to manage the sessions of the first terminal.

[0040] It can be understood that in the case of decoupling the session-related functions of the access mobile management network element, the session management network element is selected by the source RAN of the terminal, that is, the access mobile management network element does not know the corresponding relationship between the session of the terminal and the session management network element, that is, the access mobile management network element cannot interact with the session management network element corresponding to the session of the terminal.

[0041] In the embodiments of the present application, the access mobility management network element can determine whether the first terminal is located in the service area indicated by the service area information of the first terminal according to the location of the first terminal and the service area information corresponding to the first terminal in response to the third indication information (which can be carried by the signaling related to the handover) sent by the target RAN, and deliver the information (the first indication information) to the target RAN or the data management network element, and then the first indication information can be delivered to the session management network element by the target RAN or the data management network element, so that the session management network element can determine which sessions of the first terminal need to be handed over, or deactivated or released according to the first indication information. Therefore, the information transmission method provided by the embodiments of the present application can guarantee reliable session management in the handover process in the case of decoupling the session-related functions of the AMF.

[0042] In a sixth aspect, a communication apparatus is provided for implementing the methods in the above aspects and / or possible implementations of the above aspects. The communication apparatus can be the target RAN, the source RAN, the session management network element, or the access mobility management network element in any of the above aspects or possible implementations of the above aspects, or a device (e.g., a chip) including or included by the target RAN, the source RAN, the session management network element, or the access mobility management network element. The communication apparatus includes modules, units, or means corresponding to the above methods, which can be implemented by hardware, software, or by a combination of hardware and software.

[0043] In some possible designs, the communication apparatus can include a processing module and a transceiver module. The transceiver module, which can also be referred to as a transceiver unit, is configured to implement the functions of transmitting and / or receiving in any of the above aspects and / or possible implementations of the above aspects. The transceiver module can be implemented by a transceiver circuit, a transceiver, a transceiver chip, or a communication interface. The processing module can be configured to implement the processing functions in any of the above aspects and / or possible implementations of the above aspects.

[0044] In some possible designs, the transceiver module includes a transmitting module and a receiving module, which are configured to implement the functions of transmitting and receiving in any of the above aspects and / or possible implementations of the above aspects, respectively.

[0045] In a seventh aspect, a communication apparatus is provided, which includes at least one processor, and the processor is configured to execute a computer program or instructions to cause the communication apparatus to perform the methods in any of the above aspects.

[0046] In a possible implementation, the communication apparatus further includes the memory. Optionally, the memory is coupled with the processor, the memory can be integrated with the processor, or the memory can be independent of the processor. Optionally, the processor is configured to execute the computer program or the instructions stored in the memory.

[0047] In a possible implementation, the memory is independent of the communication apparatus.

[0048] In a possible implementation, the communication apparatus further includes a communication interface configured to communicate with a module outside the communication apparatus.

[0049] The communication apparatus can be the target RAN, the source RAN, the session management network element, or the access mobility management network element in any of the aspects or implementation manners described above, or an apparatus including the target RAN, the source RAN, the session management network element, or the access mobility management network element, or an apparatus included in the target RAN, the source RAN, the session management network element, or the access mobility management network element, such as a chip.

[0050] In an eighth aspect, a computer readable storage medium is provided, which stores computer programs or instructions, when running on a communication apparatus, causes the communication apparatus to perform the method in any of the aspects or implementation manners described above.

[0051] In a ninth aspect, a computer program product is provided, which includes instructions, when running on a communication apparatus, causes the communication apparatus to perform the method in any of the aspects or implementation manners described above.

[0052] In a tenth aspect, a communication apparatus (for example, the communication apparatus can be a chip or a chip system) is provided, which includes a processor configured to implement the functions involved in any of the aspects or implementation manners described above.

[0053] In some possible designs, the communication apparatus includes a memory configured to store necessary program instructions and data.

[0054] In some possible designs, when the apparatus is a chip system, the apparatus can be composed of a chip, or can include a chip and other discrete devices.

[0055] It can be understood that, when the communication apparatus in any of the sixth aspect to the tenth aspect is a chip, the sending action / function described above can be understood as output, and the receiving action / function described above can be understood as input.

[0056] The technical effects brought by the design manners of the sixth aspect to the tenth aspect can be referred to the technical effects brought by the design manners of the first aspect to the fifth aspect, which will not be repeated here.

[0057] In an eleventh aspect, a communication method is provided, including the method of any of the aspects or any implementation thereof.

[0058] In a twelfth aspect, a communication system is provided, including at least one of the devices and / or network elements of any of the aspects or any implementation thereof: a target RAN, a source RAN, a session management network element, or an access mobility management network element. BRIEF DESCRIPTION OF DRAWINGS

[0059] FIG. 1 is a schematic diagram of a 5GS service architecture according to an embodiment of the present application;

[0060] FIG. 2 is a schematic diagram of an Xn handover process according to an embodiment of the present application;

[0061] FIG. 3 is a schematic diagram of an N2 handover process according to an embodiment of the present application;

[0062] FIG. 4 is a schematic diagram of a distributed NAS signaling architecture according to an embodiment of the present application;

[0063] FIG. 5 is a schematic diagram of a possible, non-limiting system architecture according to an embodiment of the present application;

[0064] FIG. 6 is a schematic diagram of different solutions provided based on the system architecture of FIG. 5 according to an embodiment of the present application;

[0065] FIGS. 7-21 are schematic diagrams of a method of information transmission according to an embodiment of the present application;

[0066] FIGS. 22-23 are schematic diagrams of a communication apparatus according to an embodiment of the present application. DETAILED DESCRIPTION

[0067] The technical solutions of the embodiments of the present application can be applied to various communication systems, such as a wireless network (Wi-Fi) system, a vehicle-to-everything (V2X) communication system, a device-to-device (D2D) communication system, a vehicle-to-vehicle (V2V) communication system, a 4th generation (4G) mobile communication system such as a long term evolution (LTE) system, a worldwide interoperability for microwave access (WiMAX) communication system, a 5th generation (5G) mobile communication system such as a new radio (NR) system, and a future communication system.

[0068] To facilitate the understanding of the technical solutions provided by the embodiments of the present application, first, a brief introduction of the technical terms related to the present application is given. The brief introduction is as follows:

[0069] First, the 5G system (5G system, 5GS):

[0070] The 5GS can include an access network (access network, AN) and a core network (core network, CN), and can also include a terminal.

[0071] The terminal can be a terminal with transceiver function, or a chip or chip system that can be provided in the terminal. The terminal can also be referred to as user equipment (user equipment, UE), access terminal, subscriber unit, user station, mobile station (mobile station, MS), mobile station, remote station, remote terminal, mobile device, user terminal, terminal, wireless communication device, user agent or user device. The terminal in the embodiments of the present application can be a mobile phone, a cellular phone, a smart phone, a tablet computer (Pad), a wireless data card, a personal digital assistant computer (personal digital assistant, PDA), a wireless modem, a handset, a laptop computer, a machine type communication (machine type communication, MTC) terminal, a computer with wireless transceiver function, a virtual reality (virtual reality, VR) terminal, an augmented reality (augmented reality, AR) terminal, a wireless terminal in industrial control, a wireless terminal in self driving, a wireless terminal in remote medical, a wireless terminal in smart grid, a wireless terminal in transportation safety, a wireless terminal in smart city, a wireless terminal in smart home, a vehicle terminal, a road side unit (road side unit, RSU) with terminal function, etc. The terminal of the present application can also be a vehicle-mounted module, a vehicle-mounted module, a vehicle-mounted component, a vehicle-mounted chip or a vehicle-mounted unit built into a vehicle as one or more components or units.

[0072] The AN is configured to implement access-related functions, to provide access for authorized users, and to determine transmission links of different qualities for transmitting user data according to levels of the users and requirements of the services. The AN forwards control signals and user data between the terminal and the CN. The AN can include an access network device, which can also be referred to as a radio access network (RAN) device.

[0073] The CN is mainly responsible for maintaining subscription information of the mobile network, and provides functions such as session management, mobility management, policy management, and security authentication for the terminal. The CN mainly includes all or part of the following functions: a user plane function (UPF), an authentication server function (AUSF), an access and mobility management function (AMF), a session management function (SMF), a network slice selection function (NSSF), a network exposure function (NEF), a network repository function (NRF), a policy control function (PCF), a unified data management (UDM), a unified data repository (UDR), and an application function (AF).

[0074] Figure 1 is a schematic diagram of a 5GS service-based architecture provided by embodiments of the present application. As shown in Figure 1, a UE accesses a 5G network through a RAN, and the UE communicates with an AMF through an N1 interface (referred to as N1); the RAN communicates with the AMF through an N2 interface (referred to as N2); the RAN communicates with a UPF through an N3 interface (referred to as N3); an SMF communicates with the UPF through an N4 interface (referred to as N4); and the UPF accesses a data network (DN) through an N6 interface (referred to as N6). In addition, the AUSF, AMF, SMF, NSSF, NEF, NRF, PCF, UDM, UDR, or AF, and other control plane functions shown in Figure 1 interact with each other using service-based interfaces. For example, the service-based interface provided by the AUSF to the outside world is Nausf; the service-based interface provided by the AMF to the outside world is Namf; the service-based interface provided by the SMF to the outside world is Nsmf; the service-based interface provided by the NSSF to the outside world is Nnssf; the service-based interface provided by the NEF to the outside world is Nnef; the service-based interface provided by the NRF to the outside world is Nnrf; the service-based interface provided by the PCF to the outside world is Npcf; the service-based interface provided by the UDM to the outside world is Nudm; the service-based interface provided by the UDR to the outside world is Nudr; and the service-based interface provided by the AF to the outside world is Naf.

[0075] The RAN can be a device or a logical entity that provides access for a terminal. For example, the RAN can include an access network device in a future communication system, or a base station; or in a future communication system, the RAN can also have other naming ways, which are all within the protection scope of the embodiments of the present application, and the present application does not make any limitation thereto. Alternatively, the RAN can include a gNB in 5G, such as a new radio (NR) system, or one or a group (including multiple antenna panels) of antenna panels of a base station in 5G, or a network node constituting a gNB, a transmission and reception point (TRP or transmission point, TP), or a transmission measurement function (TMF), such as a building base band unit (BBU), or a centralized unit (CU) or a distributed unit (DU), an RSU with base station function, or a wired access gateway, or a core network of 5G. Alternatively, the RAN can also include an access point (AP) in a wireless fidelity (Wi-Fi) system, a wireless relay node, a wireless backhaul node, various forms of macro base stations, micro base stations (also known as small stations), relay stations, access points, wearable devices, or vehicle-mounted devices, and the like.

[0076] The UPF is mainly responsible for user data processing (forwarding, receiving, charging, etc.). For example, the UPF can serve as a session point (or terminal point) of an external protocol data unit (PDU) session connected to a data network (DN), packet routing and forwarding, user plane part policy rule execution and data packet inspection, and user plane quality of service (QoS) processing. Among them, the DN can refer to an operator network that provides data transmission services for users, such as an internet protocol (IP) multi-media service (IMS), or the Internet. The DN can be an operator external network or an operator controlled network, which is used to provide service services to terminals.

[0077] It can be understood that the core of the user plane is to establish a PDU session, that is, to establish a PDU session between the terminal and the DN, and to provide an end-to-end (E2E) user plane connection 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 the data packets transmitted between the terminal and the UPF. In addition, the PDU session can include a transmission path between the DN and the UPF network element, and a transmission path (or tunnel) between the UPF and the RAN. The tunnel can be a general packet radio service tunneling protocol for the user plane (GTP-U) tunnel, and the GTP-U tunnel is used to carry the data packets transmitted in the user plane.

[0078] In addition, in the PDU session, the UPF can include a protocol data unit session anchor (PSA), or PSA-UPF, which can refer to a UPF directly connected to the DN through N6. It should be understood that an intermediate PDU (I-UPF) can also be included in the PDU session, and the I-UPF is used to transfer user plane data between the RAN and the PSA-UPF.

[0079] The AUSF is mainly used to perform security authentication of the terminal.

[0080] The AMF is mainly used for mobility management in the mobile network. For example, user location update, user registration network, user handover, etc.

[0081] The SMF is mainly used for session management in the mobile network. For example, session establishment, modification, release. Specific functions are, for example, user IP address allocation, selection of UPF providing packet forwarding function, etc.

[0082] The PCF mainly supports providing a unified policy framework to control network behavior, providing policy rules to control layer network functions, and being responsible for obtaining user subscription information related to policy decision. The PCF can provide policies such as quality of service (QoS) policies and slice selection policies to the AMF and the SMF.

[0083] The NSSF is mainly used to select network slices for terminals.

[0084] The NEF is mainly used to support the opening of capabilities and events.

[0085] The UDM is mainly used to store user data, such as subscription information, authentication / authorization data, etc.

[0086] The UDR is mainly used to store structured data, including subscription information and policy data, externally exposed structured data, and application-related data.

[0087] The AF mainly supports interaction with the CN to provide services, such as affecting data routing decisions, policy control functions, or providing some services of third parties to the network side.

[0088] It can be understood that the functions mentioned in the embodiments of the present application can also be expressed as functional network elements or functional entities, for example, the RAN can be expressed as a NEF network element, or a RAN device, or a RAN apparatus, and the like, and for example, the SMF can be expressed as an SMF network element, and the like, and the like, without limitation.

[0089] In addition, the functions and functional network elements are mixed below, for example, the SMF and the SMF network element are mixed, both have the same meaning, and are uniformly described here, and the following will not be repeated.

[0090] Second, the handover process:

[0091] It can be understood that after the UE is registered to the network, a PDU session can be established to realize communication of services with a certain DN. Among them, the network can configure related policies to control the UE to be able to connect to certain DN in a specific service area, and the policy can be UE granularity or DN granularity. For example, when the UE moves from one cell to another cell, the UE needs to connect to the new cell through the Xn handover process or the N2 handover process. In the process of handover, the AMF needs to determine whether the UE can continue to use the established PDU session according to the location information of the cell to which the UE switches.

[0092] The following describes the service area, Xn handover, and N2 handover involved in the above handover process.

[0093] 2.1, Service area:

[0094] In the handover process, the service area involves the DN side service area (such as the local area data network (LADN)), and the service area for the mobile management of the UE (such as the service area restriction (SAR)), which are described below.

[0095] The service area indicated by the LADN can be represented by one or more tracing areas (TA) and / or cells, and service communication (or service transmission) can be performed within the service area indicated by the LADN. It can be understood that the LADN can be associated with a DN and / or a slice network. In addition, the LADN can be provided by a DN or single network slice selection assistance information (S-NSSAI).

[0096] The SAR defines which areas the UE can communicate with the network for certain service (for example, non-emergency service) transmission and which areas the UE is not allowed to communicate with the network for service transmission. It can be understood that the service area indicated by the SAR can include an allowed area and a non-allowed area. Among them, the UE can perform non-emergency service transmission in the allowed area, and the UE cannot perform non-emergency service transmission in the non-allowed area. For example, in the case that the UE is located in the non-allowed area, neither the UE nor the network is allowed to initiate a service request or session management (SM) signaling for non-emergency service transmission, and emergency service transmission can be performed; for another example, in the case that the UE enters the non-allowed area, network selection or cell reselection can not be triggered; for another example, in the case that the UE is located in the non-allowed area, emergency service transmission can be performed, and the embodiments of the present application do not make specific limitations.

[0097] It should be understood that in the case that the UE is located in the non-allowed area, the UE can camp on the non-allowed area and can perform some non-emergency service transmission, but cannot perform emergency service transmission.

[0098] It can be understood that the above SAR is mainly used for mobility management and belongs to the AMF-related policy. The above LADN is the service area restriction of the data network and belongs to the session (namely, SMF) related policy.

[0099] 2.2, Xn handover:

[0100] Xn is an interface for interaction between RANs. The Xn handover is mainly used for the case that the UE moves in a small range and does not involve cross-AMF handover, that is, after the service RAN of the UE is switched from the source RAN (S-RAN) to the target RAN (T-RAN), the AMF on the CN side does not change.

[0101] FIG. 2 is a flow diagram of an Xn handover according to an embodiment of the present application. As shown in FIG. 2, the flow mainly involves the interaction between the UE, the source RAN, the target RAN, the AMF, the SMF, and the UPF.

[0102] As shown in FIG. 2, the Xn handover flow includes the following steps:

[0103] S201, handover preparation.

[0104] It can be understood that when the UE moves from the coverage area of the source RAN to the coverage area of the target RAN, the UE should be handed over from the source RAN to the target RAN. The target RAN can obtain the temporary identifier of the UE and the session-related information (e.g., including the PDU session identity (ID), the context information of the UE, etc.) of the UE from the source RAN through the Xn interface for PDU session transmission.

[0105] It can be understood that step S201 can include RAN handover completion, i.e., the UE completes the handover on the air interface. For example, after the air interface connection of the UE is handed over from the source RAN to the target RAN, the UE can send an RRC reconfiguration complete (RRCReconfigurationComplete) message to the target RAN, which is used to indicate that the air interface handover is completed.

[0106] 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 can include the list of PDU sessions to be switched, the list of PDU sessions failed to switch, the temporary identifier of the UE, or the location information of the UE, etc.

[0107] It should be understood that the location information of the UE can be indicated by the area where the UE is located, which can be the coverage area (or service area) of the target RAN, or the service area where the UE is located can also be determined by the identifier of the target RAN. For example, the N2 path switch request can 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), etc. For another example, the N2 path switch request can include the identifier of the target RAN, so that the AMF can determine that the location of the UE is in the service area of the target RAN according to the identifier of the target RAN.

[0108] S203, the AMF sends a session modification (or referred to as update) request to the SMF. Correspondingly, the SMF receives the session modification request from the AMF. Wherein, the session modification request is used to modify a session management (SM) context.

[0109] It can be understood that the AMF sends the session modification request to the SMF corresponding to each session of the multiple sessions of the UE, that is, the PDU session of the UE is taken as the granularity for session management in the handover process of the UE.

[0110] In addition, the AMF can send the above-mentioned session modification request by invoking the PDU session update SM context request (Nsmf_PDUSession_UpdateSMContext Request) service operation of the SMF.

[0111] It can be understood that the AMF can send the corresponding session update request according to whether the UE is located in the service area indicated by the above-mentioned service area information. Specifically, the AMF can obtain the subscription data of the UE from the UDM, which can include the SAR information of the UE, and then the AMF can determine whether the UE is located in the allowed area according to the location information of the UE included in the N2 path switching request in step S202 and the SAR information of the UE.

[0112] If the AMF determines that the UE is not in the allowed area indicated by the SAR information, the UE is not allowed to establish other sessions except for emergency service sessions (i.e., the UE is not allowed to establish non-emergency service sessions), and then the above-mentioned session modification request can include indication information for indicating that the UE is not in the allowed area indicated by the SAR information, so that the AMF can send the indication information to the SMF corresponding to each session of the multiple sessions of the UE, so that the SMF can deactivate or release other sessions except for emergency service sessions in the multiple sessions of the UE according to the indication information, that is, so that the SMF can deactivate or release non-emergency service sessions in the multiple sessions of the UE.

[0113] Exemplarily, the AMF can send the above-mentioned indication information to the SMF corresponding to each session of the multiple sessions of the UE by invoking the event exposure notification (Namf_EventExposure_Notify) service operation of the AMF.

[0114] It can be understood that the above-mentioned deactivation or release of the session, or the session deactivation or release, can mean that the SMF releases the PDU session resource, including releasing the UPF corresponding to the PDU session.

[0115] If the AMF determines that the UE is located in the allowed area indicated by the SAR information, the AMF can determine whether the UE is located in the service area indicated by the LADN information associated with each of the multiple sessions of the UE according to the LADN information (which can be pre-configured) associated with each of the multiple sessions of the UE.

[0116] For example, assuming that the AMF determines that the UE is located in the service area indicated by the LADN information associated with a certain session of the multiple sessions of the UE, the session modification request sent by the AMF to the SMF corresponding to the session can include indication information for indicating that the UE is located in the service area indicated by the LADN information, so that the SMF can perform session switching for the session according to the indication information.

[0117] It can be understood that the session switching can include modifying the information of the serving RAN in the session management context from the source RAN to the target RAN. For example, the session switching can include configuring a tunnel between the UPF corresponding to the session and the access side (i.e., the target RAN, i.e., the RAN addressed by N3). It can be understood that the session switching can 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 limited in the embodiments of the present application.

[0118] For another example, assuming that the AMF determines that the UE is not located in the service area indicated by the LADN information associated with a certain session of the multiple sessions of the UE, the session modification request sent by the AMF to the SMF corresponding to the session can not include indication information for indicating that the UE is located in the service area indicated by the LADN information, and further implicitly indicates that the UE is not located in the service area indicated by the LADN information, so that the SMF releases or deactivates the session.

[0119] It should be understood that the session management performed by the SMF side according to the session modification request is mainly related to the UPF, and the interaction between the SMF and the UPF is described below.

[0120] S204, the SMF sends an N4 session modification request to the UPF. Correspondingly, the UPF receives the N4 session modification request from the SMF.

[0121] The N4 session modification request can include session switching, or session deactivation or release.

[0122] S205, the UPF sends an N4 session modification response to the SMF. Correspondingly, the SMF receives the N4 session modification response from the UPF.

[0123] It can be understood that the N4 session modification response can be used to indicate that the session modification is successful. For example, the session handover is successful, or the session deactivation or release is successful.

[0124] S206, the UPF sends an N3 end marker to the source RAN.

[0125] It can be understood that the N3 end marker is used to indicate that the UPF ends sending the data packet to the source RAN.

[0126] S207, the source RAN sends the N3 end marker to the target RAN.

[0127] S208, the SMF sends a session modification response to the AMF. Accordingly, the AMF receives the session modification response from the SMF.

[0128] The session modification response is used to indicate that the session modification is successful, i.e., the session management context update is successful.

[0129] It can be understood that the SMF can send the above-mentioned session modification response by invoking the PDU session update SM context response (Nsmf_PDUSession_UpdateSMContext Response) service operation of the SMF.

[0130] S209, the AMF sends an N2 path switch request acknowledgement (ACK) to the target RAN. Accordingly, the target RAN receives the N2 path switch request acknowledgement from the AMF.

[0131] S210, the target RAN sends a release resource message to the source RAN. Accordingly, the source RAN receives the release resource message from the target RAN.

[0132] The release resource message is used to instruct the source RAN to release the related resources of the UE, such as wireless and control plane resources, etc.

[0133] Optionally, the flowchart shown in FIG. 2 further includes:

[0134] S211, a registration procedure is performed between the UE, the target RAN, and the AMF.

[0135] 2.3, N2 handover:

[0136] It can be understood that the N2 handover is different from the above-mentioned Xn handover. Because the UE moves far away, the source RAN can not be able to find the target RAN through the Xn interface, and the source RAN can find the target RAN through the source AMF, which will be introduced in detail below.

[0137] FIG. 3 is a flow diagram of N2 handover according to an embodiment of the present application. As shown in FIG. 3, the N2 handover includes a preparation phase and an execution phase. As shown in FIG. 3, the preparation phase includes the following steps:

[0138] S301, the source RAN sends a handover required message to the source AMF. Accordingly, the source AMF receives the handover required message from the source AMF.

[0139] The handover required message includes an identifier of the target RAN, security information sent to the target RAN, or a mobility restriction list, etc.

[0140] S302, the source AMF selects a target AMF.

[0141] It can be understood that the source AMF can select a target AMF serving the target RAN according to the handover required message.

[0142] S303, the source AMF sends a UE context setup request to the target AMF. Accordingly, the target AMF receives the UE context setup request from the source AMF.

[0143] The UE context setup request includes an identifier of the UE, SAR information, session information of the UE, and SMF information associated with the session, etc.

[0144] S304, the target AMF sends a session modification request to the SMF. Accordingly, the SMF receives the session modification request from the target AMF.

[0145] It can be understood that the specific implementation of step S304 is similar to step S203, and the difference is that step S304 is in the preparation phase of the handover, and here it is determined whether the UE is located in the allowed area indicated by the SAR information. As for determining whether the UE is located in the service area indicated by the LADN information associated with each session, it is performed in the execution phase of the handover. In addition, the specific implementation of step S304 can refer to step S203.

[0146] S305, session management.

[0147] It can be understood that, as the relevant description of the foregoing step S203, the session management can include session switching, or session deactivation or release, etc. Among them, in step S305, the SMF can determine whether a new UPF is needed according to the session modification request of step S304, and then execute steps S305a and S305b in the case of not needing a new UPF. In addition, in the case of needing a new UPF (for example, 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, S305c and S305d can be executed.

[0148] 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.

[0149] It can be understood that the specific implementation of step S305a can be referred to step S204, which will not be repeated here.

[0150] S305b, the PSA-UPF sends an N4 session modification response to the SMF. Correspondingly, the SMF receives the N4 session modification response from the UPF.

[0151] It can be understood that the specific implementation of step S305b can be referred to step S205, which will not be repeated here.

[0152] 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.

[0153] Among them, the N4 session establishment request is used to establish a tunnel between the target UPF and the target AMF side.

[0154] 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.

[0155] Among them, the N4 session establishment response is used to indicate that the session establishment is successful.

[0156] It can be understood that the session management process of the above step S305 can also include inserting a new I-UPF, which will not be repeated here.

[0157] S306, the SMF sends a session modification response to the target AMF. Correspondingly, the target AMF receives the session modification response from the SMF.

[0158] It can be understood that the session modification response is used to indicate that the session modification is successful, i.e., the session management context update is successful.

[0159] In addition, the above steps S304-S306 are mainly used for the target AMF to obtain the tunnel information of the UPF.

[0160] S307, the target AMF sends a handover request to the target RAN. Correspondingly, the target RAN receives the handover request from the target AMF.

[0161] It can be understood that the target AMF can send the handover request to the target RAN according to the identifier of the target RAN. In addition, the handover request can contain information such as security information from the source RAN, a mobility restriction list, etc.

[0162] 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.

[0163] The handover request ACK can include a container to be sent to the source RAN, a list of PDU sessions that can be switched, or PDU sessions that cannot be switched, etc.

[0164] It can be understood that the target RAN can also allocate a new air interface temporary identifier for the UE according to the handover request, so as to facilitate the subsequent execution phase to perform session management.

[0165] 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.

[0166] It can be understood that according to the handover request response of the target RAN, the target AMF sends a PDU session update request to the SMF corresponding to the PDU session. For the switched session, the AN side tunnel information of the session is updated; for the session that cannot be switched, the SMF is requested to release the corresponding session.

[0167] It should be understood that the main purpose of step S309 is to exchange 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 described here.

[0168] 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.

[0169] It can be understood that the specific implementation of step S310 can refer to step S306, and details are not described here.

[0170] S311, the target AMF sends a UE context setup response to the source AMF. Accordingly, the source AMF receives the UE context setup response from the target AMF.

[0171] It can be understood that after step S311, the source AMF, the target AMF, and the target RAN exchange the related information of the forwarding path, and are ready for the handover.

[0172] As shown in FIG. 3, the execution stage includes the following steps:

[0173] S312, the RAN handover is completed.

[0174] It can be understood that the completion of the RAN handover means that the UE completes the handover on the air interface. In addition, the difference between step S312 and step S201 is that the source AMF sends a handover command to the source RAN, and then the source RAN sends the handover command to the UE, so that the UE and the target RAN complete the handover on the air interface, that is, the RAN handover is completed under the trigger of the handover command. For example, after the UE and the cell where the target RAN are synchronized, the UE sends a hand confirm to the target RAN, indicating that the air interface handover is completed.

[0175] S313, the target RAN sends a handover notification to the target AMF. Accordingly, the target AMF receives the handover notification from the target RAN.

[0176] The handover notification is used to notify the target AMF that the air interface handover has been completed. The handover notification can include a temporary identifier of the UE, and location information (such as a TA identifier or a cell identifier) of the UE.

[0177] S314, the target AMF sends a session modification request to the SMF. Accordingly, the SMF receives the session modification request from the target AMF.

[0178] It should be understood that the specific implementation of step S314 is similar to step S203 in FIG. 2. According to the location of the UE, the SAR information, and the LADN information associated with the session, 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. Details can be referred to step S203, and details are not described here.

[0179] S315, session management.

[0180] It can be understood that, as the relevant description of the foregoing step S305, according to whether the UE is located in the service area indicated by the service area information, whether the UPF is newly added, and the like, the SMF can send a session modification request to the target UPF, or the source UPF, or the PSA-UPF, and further receive a session modification response from the target UPF, or the source UPF, or the PSA-UPF, which will not be described herein again.

[0181] S316, the SMF sends a session modification response to the target AMF. Accordingly, the target AMF receives the session modification response from the SMF.

[0182] S317, the registration process.

[0183] It can be understood that, according to the foregoing relevant description of the Xn handover and the N2 handover, in the process of UE handover, the AMF determines whether the PDU session of the UE can be established (that is, whether it needs to be deactivated or released) according to whether the UE is located in the allowed area indicated by the SAR information and the service area indicated by the LADN information, and further sends a session modification request to the SMF. In other words, in addition to being responsible for UE location judgment (that is, mobility management), the AMF is also responsible for functions related to session management (sending a session modification request to the SMF). In addition, the interaction between the RAN and other NFs in the core network except the AMF is forwarded through the AMF, which further causes poor flexibility.

[0184] Therefore, in the face of new requirements of future services, it is necessary to improve the architecture of the existing 5GS in the future communication network (or future communication system) to improve the flexibility of interaction between the UE and the NF in the core network, and meet the new requirements of future services. The following specifically introduces the relevant description of the improvement of the architecture of the 5GS.

[0185] Third, distributed non-access stratum (NAS) architecture:

[0186] In the current research of the future communication network (or future communication system), the distributed NAS signaling architecture can be used between the RAN and the core network, which can enable the RAN to send related messages to the AMF and the SMF, respectively, so that the RAN can not have to send all NAS signaling to the AMF and then be forwarded by the AMF, thereby decoupling the AMF function and enhancing flexibility.

[0187] It can be understood that, under the distributed NAS architecture, the RAN can discover the NF in the CN through the NRF or other ways, and then can directly communicate with different NFs in the CN, for example, the RAN can realize the interaction of signaling through the service interface between the RAN and the NF.

[0188] FIG. 4 is an architecture diagram of a RAN sending a handover request according to an embodiment of the present application. As shown in FIG. 4, when the distributed NAS architecture is adopted, the RAN can discover the AMF and the SMF and other NFs through the NRF, and the RAN can directly send the NAS signaling to the AMF and the SMF in the core network through the service interface respectively.

[0189] For example, in the process of the serving RAN of the UE being handed over from the source RAN to the target RAN, the source RAN can select the SMF and deliver the temporary identifier of the UE and the session-related information of the UE (including the SMF corresponding to each session of the multiple sessions of the UE) 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 can indicate that the serving RAN of the UE is handed over from the source RAN to the target RAN, and then the AMF can update the information of the serving RAN of the UE according to the first path handover request. The second path handover request can be used to request that the serving RAN of the UE is handed over from the source RAN to the target RAN, and then the SMF can perform session management (such as session handover, or session deactivation or release) according to the second path handover request, that is, update the tunnel information and notify the UPF associated with the session.

[0190] It can be understood that, by decoupling the session-related functions of the AMF in the manner shown in FIG. 4, flexibility can be improved. However, how to ensure that the session management can be reliably performed according to the restrictions of the area during the handover process after decoupling the session-related functions of the AMF has not been solved.

[0191] Specifically, referring to FIG. 4, decoupling the session-related functions of the AMF means that the AMF will not send a session modification request to the SMF (see step S203 for details), and the SMF will only receive the second path handover request from the RAN, which will cause the SMF to be unable to determine whether the UE is located in the allowed area indicated by the SAR information of the UE and / or the service area indicated by the LADN information corresponding to the session of the UE, and thus the SMF is unable to determine which sessions need to be deactivated or released and which sessions need to be handed over.

[0192] To solve the above technical problems, the embodiments of the present application provide the following technical solutions, which will be described below with reference to the accompanying drawings.

[0193] In the embodiments of the present application, the indication can include direct indication and indirect indication, and can also include explicit indication and implicit indication. The information indicated by certain information is referred to as to-be-indicated information. In the implementation process, there are many ways to indicate the to-be-indicated information, for example, but not limited to, the to-be-indicated information can be directly indicated, such as the to-be-indicated information itself or an index of the to-be-indicated information. The to-be-indicated information can also be indirectly indicated by indicating other information, where the other information and the to-be-indicated information have an association relationship. The to-be-indicated information can also be indicated only by a part of the to-be-indicated information, and the other part of the to-be-indicated information is known or agreed in advance. For example, the indication of a specific information can also be achieved by means of the arrangement order of various information agreed in advance (for example, specified by a protocol), thereby reducing the indication overhead to a certain extent. Meanwhile, a common part of various information can be identified and uniformly indicated, so as to reduce the indication overhead caused by separately indicating the same information.

[0194] In addition, the specific indication manner can also be various existing indication manners, for example, but not limited to, the above indication manners and various combinations thereof. The specific details of various indication manners can refer to the prior art, and will not be described herein. As known from the above, for example, when multiple information of the same type needs to be indicated, the indication manners of different information can be different. In the implementation process, the required indication manner can be selected according to the specific needs, and the selected indication manner is not limited in the embodiments of the present application. In this way, the indication manner involved in the embodiments of the present application should be understood as covering various methods that can enable the to-be-indicated party to know the to-be-indicated information.

[0195] It should be understood that the to-be-indicated information can be sent as a whole, or can be sent separately into multiple sub-information, and the sending period and / or sending occasion of the sub-information can be the same or different. The specific sending method is not limited in the embodiments of the present application. The sending period and / or sending occasion of the sub-information can be predefined, for example, predefined according to a protocol, or configured by the sending end device by sending configuration information to the receiving end device.

[0196] In the present application, the "sending information" can be understood as that a device (or a communication entity) sends information to another device (or a communication entity), or can also be understood as that a logical module in a device sends information to another logical module. For example, "RAN sends information" can be understood as that the RAN sends information to another device (such as SMF), or can be understood as that a logical module 1 in the RAN sends information to a logical module 2 in another device.

[0197] In this application, "receiving information" can be understood as a device (or a communication entity) receiving information from another device (or a communication entity), or can also be understood as a logical module inside a device receiving information from another logical module. For example, "RAN (or RAN network element) receiving information" can be understood as the RAN receiving information from another device (such as SMF), or can be understood as a logical module 1 in the RAN receiving information from a logical module 2 in another device.

[0198] In this application, "sending information to (for example, SMF)" or related illustrations in the drawings can be understood as that the destination of the information is the SMF. It can include directly or indirectly sending information to the SMF. "Receiving information from (for example, RAN)" or "receiving information from (for example, RAN)" or "receiving information sent by (for example, RAN)", or related illustrations in the drawings can be understood as that the source of the information is the RAN, and can include directly or indirectly receiving information from the RAN. The information between the source and the destination of the information sending can be processed as necessary, for example, format change, etc., but the destination can understand the valid information from the source. Similar expressions in this application can be similarly understood, and will not be repeated here.

[0199] "Predefined" or "preconfigured" can be realized by pre-storing corresponding codes, tables or other means that can be used to indicate related information in the device, and the specific implementation manner is not limited in the embodiments of the application. Wherein, "storing" can mean storing in one or more memories. The one or more memories can be separately arranged, or can be integrated in the encoder or decoder, processor, or communication device. The one or more memories can be part of the separately arranged, and part of the integrated in the decoder, processor, or communication device. The type of memory can be any form of storage medium, and the embodiments of the application do not limit this.

[0200] The "protocol" involved in the embodiments of the application can refer to a protocol family in the communication field, a standard protocol similar to the frame structure of the protocol family, or a related protocol applied to a future communication system, and the embodiments of the application do not make specific limitations.

[0201] In the embodiments of the application, "when", "in the case of", "if", and "if" and the like all refer to the device making corresponding processing under certain objective conditions, and are not limited by time, and do not require the device to have a judgment action when implemented, nor does it mean that there are other limitations.

[0202] In the description of the embodiments of the present application, unless otherwise specified, " / " represents a "or" relationship between the objects associated in front and behind, for example, A / B can represent A or B; "and / or" in the embodiments of the present application is only a description of the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent: A exists alone, A and B exist simultaneously, and B exists alone, where A, B can be singular or plural. And, in the description of the embodiments of the present application, unless otherwise specified, "multiple" means two or more than two. "At least one of the following" or the like means any combination of the items, including any combination of single item or multiple items. For example, at least one of a, b or c can represent: a, b, c, a-b, a-c, b-c, or a-b-c, where a, b, c can be single or multiple. In addition, in order to clearly describe the technical solutions of the embodiments of the present application, in the embodiments of the present application, "first", "second", etc. are used to distinguish the same items or similar items with basically the same function and role. The skilled in the art can understand that "first", "second", etc. do not limit the quantity and execution order, and "first", "second", etc. also do not limit the difference. At the same time, in the embodiments of the present application, "exemplary" or "for example" means to present relevant concepts in a specific way for understanding.

[0203] The network architecture and service scenario described in the embodiments of the present application are used to more clearly illustrate the technical solutions of the embodiments of the present application, and do not constitute a limitation on the technical solutions provided by the embodiments of the present application. The skilled in the art can know that, with the evolution of network architecture and the appearance of new service scenarios, the technical solutions provided by the embodiments of the present application are also applicable to similar technical problems.

[0204] In order to understand the embodiments of the present application, first, a communication system is taken as an example to describe the communication system applicable to the embodiments of the present application in detail.

[0205] FIG. 5 is a possible, non-limiting system architecture diagram provided by the embodiments of the present application. As shown in FIG. 5, the system includes: a RAN and a session management network element. Wherein, the RAN can be a target RAN or a source RAN in the terminal handover process. The session management network element can be, for example, a network element for session management of the terminal (such as the SMF in FIG. 1), or a network element for session management in future communication systems, which is not limited in the embodiments of the present application.

[0206] It should be understood that the system architecture shown in FIG. 5 can also include other network elements, such as an access mobility management network element, or a data management network element, etc., and the embodiments of the present application do not make specific limitations thereto.

[0207] In addition, the access mobility management network element can refer to a network element for mobility management in a mobile network (such as the AMF in FIG. 1), or a network element for mobility management in a future communication system, and the embodiments of the present application do not make specific limitations thereto.

[0208] In addition, the data management network element can refer to a network element for storing subscription information and / or policy data of a terminal (such as the UDR in FIG. 1), or a network element for storing subscription information and / or policy data of a terminal in a future communication system, and the embodiments of the present application do not make specific limitations thereto.

[0209] In order to ensure that the session management can be reliably performed in the handover process in the case of decoupling the session-related functions of the AMF, the system shown in FIG. 5 provides the following three solutions, which will be described below in conjunction with FIG. 6.

[0210] FIG. 6 is a schematic diagram of different solutions provided by the system architecture shown in FIG. 5 according to an embodiment of the present application. As shown in FIG. 6, (a) in FIG. 6 is a schematic diagram of solution 1, (b) in FIG. 6 is a schematic diagram of solution 2, and (c) in FIG. 6 is a schematic diagram of solution 3.

[0211] For solution 1:

[0212] As shown in (a) in FIG. 6, in solution 1, the RAN determines whether the terminal is located in the service area indicated by the service area information corresponding to the terminal, and indicates it to the session management network element. Based on the difference of the RAN (target RAN or source RAN), solution 1 can be divided into two sub-solutions, which will be introduced below.

[0213] Solution 1-1:

[0214] In a possible implementation, in the process of switching the service RAN of the first terminal from the source RAN to the target RAN, the target RAN obtains the service area information corresponding to the first terminal; the target RAN determines the first indication information according to the location information of the first terminal and the service area information, and sends the first indication information to the session management network element. The first indication information is used to indicate whether the first terminal is located in the service area indicated by the service area information. The session management network element is used to manage the session of the first terminal.

[0215] Solution 1-2:

[0216] In a possible implementation, the source RAN acquires the corresponding service area information of the first terminal, and in the process of switching the service RAN of the first terminal from the source RAN to the target RAN, the source RAN determines the first indication information according to the location information of the first terminal and the service area information, and then sends the first indication information to the session management network element. The first indication information is used to indicate whether the first terminal is located in the service area indicated by the service area information. The session management network element is used to manage the session of the first terminal.

[0217] That is, the target RAN or the source RAN can determine whether the first terminal is located in the service area indicated by the service area information according to the location information of the first terminal and the service area information by acquiring the corresponding service area information of the first terminal, and then indicate to the session management network element through the first indication information, so that the session management network element can determine which session of the first terminal needs to be switched, or session deactivated or released according to the first indication information. Therefore, the solution 1 provided in the embodiments of the present application can guarantee reliable session management in the handover process in the case of decoupling the session-related functions of the AMF.

[0218] In addition, since the target RAN or the source RAN determines whether the first terminal is located in the service area indicated by the service area information corresponding to the first terminal, and then the target RAN sends the signaling about the handover to the access mobility management network element, it is not necessary to send the signaling about the handover to the session management network element based on the information about whether the first terminal is located in the service area fed back by the access mobility management network element, so that the signaling about the handover sent by the target RAN to the session management network element and the access mobility management network element has no timing requirement, which can better decouple the functions of the access mobility network element and the session management network element, and further enhance the flexibility.

[0219] For solution 2:

[0220] As shown in (b) of FIG. 6, in solution 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 thereon.

[0221] In a possible implementation, the session management network element acquires service area information corresponding to the first terminal; in the process of switching the service RAN of the first terminal 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 switching the service RAN of the first terminal from the source RAN to the target RAN, and the first request including 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 according to the location information of the first terminal and the service area information; and the session management network element manages the session of the first terminal according to whether the first terminal is located in the service area indicated by the service area information.

[0222] That is, the session management network element acquires the service area information corresponding to the first terminal, and then in the process of switching the service RAN of the first terminal from the source RAN to the target RAN, the session management network element can determine whether the first terminal is located in the service area indicated by the service area information according to the location information of the first terminal and the service area information in response to the first request sent by the source RAN or the target RAN, so as to determine which session of the first terminal needs to be switched, or deactivated or released. Therefore, the scheme 2 provided in the embodiment of the application can guarantee reliable session management in the process of switching in the case of decoupling the session-related functions of the AMF.

[0223] 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 request about switching from the target RAN, the signaling about switching sent by the target RAN to the session management network element and the access mobile management network element has no timing requirement, so that the functions of the access mobile network element and the session management network element can be better decoupled, and the flexibility is further enhanced.

[0224] For scheme 3:

[0225] As shown in (c) of FIG. 6, in scheme 3, the access mobile 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 result of the determination to the target RAN or the data management network element, so that the session management network element can acquire the result of the above determination from the target RAN or the data management network element.

[0226] In a possible implementation, in a process of switching the serving RAN of the first terminal from the source RAN to the target RAN, the access mobility management network element receives third indication information from the target RAN, the third indication information being used to indicate that the serving RAN of the first terminal is switched from the source RAN to the target RAN; the access mobility management network element determines first indication information according to 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 in the service area indicated by the service area information; and the access mobility management network element sends the first indication information to the target RAN or the data management network element, the target RAN or the data management network element being used to provide the first indication information to the session management network element, and the session management network element being used to manage the session of the first terminal.

[0227] It can be understood that, in the case of decoupling the session-related functions of the access mobility management network element, 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 session of the terminal and the session management network element, that is, the access mobility management network element cannot interact with the session management network element corresponding to the session of the terminal.

[0228] That is, the access mobility management network element can determine, in response to the third indication information (which can be carried by signaling related to switching) sent by the target RAN, whether the first terminal is located in the service area indicated by the service area information corresponding to the first terminal according to the location of the first terminal and the service area information, and deliver the information (first indication information) to the target RAN or the data management network element, and then the first indication information can be delivered to the session management network element through the target RAN or the data management network element, so that the session management network element can determine, according to the first indication information, which sessions of the first terminal need to be switched, or deactivated or released. Therefore, the scheme 3 provided in the embodiments of the present application can guarantee reliable session management in the process of switching in the case of decoupling the session-related functions of the AMF.

[0229] It should be understood that, with the evolution of the network, the system shown in FIG. 5 can also support or include other network functions, such as AI or perception-related functions, which are not limited in the embodiments of the present application.

[0230] In addition, with the evolution of the network, the names of the network elements involved in the above-mentioned FIG. 5 will also change, which are not limited in the embodiments of the present application.

[0231] The interaction process between the network elements / devices in the system shown in FIG. 5 will be specifically introduced below in combination with FIGS. 7-21. The information transmission method provided in the embodiments of the present application can be applied to the above-mentioned system and specifically applied to various scenarios / processes mentioned in the above-mentioned system.

[0232] The following first introduces the scheme 1.

[0233] Scheme 1-1:

[0234] FIG. 7 is a flow diagram of an information transmission method according to an embodiment of the present application. The information transmission method is applicable to the scheme 1-1 shown in (a) of FIG. 6, and mainly involves the interaction among the source RAN, the target RAN, and the session management network element. As shown in FIG. 7, the information transmission method includes the following steps.

[0235] S701. In the process of switching the first terminal from the service RAN of the source RAN to the RAN of the target RAN, the target RAN acquires the service area information corresponding to the first terminal from the source RAN.

[0236] S702. The target RAN determines first indication information according to the location information of the first terminal and the service area information. The first indication information is used to indicate whether the first terminal is located in the service area indicated by the service area information.

[0237] S703. The target RAN sends the first indication information to the session management network element. Correspondingly, the session management network element receives the first indication information from the target RAN. The session management network element is used to manage the session of the first terminal.

[0238] S704. The session management network element manages the session of the first terminal according to the first indication information.

[0239] It can be understood that the management of the session can include session switching, or session deactivation or release, etc. In addition, the specific principle of the session management network element managing the session of the first terminal according to the first indication information can be referred to the foregoing related description of steps S203-S208, step S305, or step S315 in the “Xn handover” and “N2 handover”, which will not be repeated here.

[0240] The steps S701-S703 will be described respectively.

[0241] For step S701:

[0242] In a 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.

[0243] It can be understood that the SAR information can be referred to the foregoing related description of SAR in the “2.1 Service Area” in the preceding section of the detailed description, which will not be repeated here.

[0244] In addition, the service area information of the data network corresponding to the session of the first terminal can refer to the related description of LADN in "2.1 Service Area". It should be understood that the service area information of the data network in the embodiments of the present application can include the LADN associated with the DN and / or slice network, which is uniformly described here and will not be repeated below.

[0245] 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 then determine whether the first terminal is located in the allowed 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.

[0246] 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 several cells, or one or several TAs, which is not limited in the embodiments of the present application.

[0247] It can be understood that the target RAN obtains the above SAR information and / or LADN information from the source RAN, which can mean that the source RAN sends the above SAR information and / or LADN information to the target RAN. The source RAN can obtain the above SAR information and / or LADN information from the access mobility management network element. It should be understood that the timing of the source RAN obtaining the above SAR information and / or LADN information from the access mobility management network element is not limited, for example, after the source RAN registers to the NRF, the access mobility management network element can send the LADN information corresponding to the supported DN / S-NSSAI pair to the source RAN; for another example, after the source RAN sends the N2 message or reports the RAN information to the access mobility management network element, the access mobility management sends the SAR information and / or LADN information of the first terminal to the source RAN; for another example, after the first terminal establishes a PDU session, the access mobility management network element 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, which is not limited in the embodiments of the present application.

[0248] In addition, the source RAN can also be preconfigured with the LADN information.

[0249] It can also be understood that in the N2 handover process, the target RAN can also obtain the above SAR information and / or LADN information from the target access mobility management network element, which is not limited in the embodiments of the present application.

[0250] For step S702:

[0251] It can be understood that the position information of the first terminal can specifically indicate the indication information indicating the position of the first terminal, for example, the coordinates of the first terminal, or the identifier of the TA and / or cell where the first terminal is located, etc.; or can also be the indication information indirectly indicating the position of the first terminal, for example, the identifier of the service area of the target RAN (for example, 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 related description in step S201, which will not be repeated here.

[0252] In addition, the position information of the first terminal can be obtained by the target RAN from the source RAN, for example, in the Xn handover process, the source RAN can send the position information of the first terminal to the target RAN through step S201 in FIG. 2; for another example, in the N2 handover process, the target access mobility management network element sends the position information of the first terminal to the target RAN through step S307 in FIG. 3; for another example, the target RAN can obtain the position information of the first terminal through other network elements or the first terminal, and the embodiments of the present application do not make specific limitations thereon.

[0253] It can also be understood that the target RAN can determine whether the first terminal is located in the service area indicated by the service area information (for example, SAR information and / or LADN information) corresponding to the first terminal according to the position information of the first terminal and the service area information. The specific implementation is similar to the determination of whether the UE is located in the allowed area indicated by the SAR information and the service area indicated by the LADN information by the AMF in step S203 of FIG. 2, which will not be repeated here.

[0254] For step S703:

[0255] It can be understood that the target RAN sending the first indication information to the session management network element means that the target RAN can obtain the identifier and / or address information of the session management network element, and then the target RAN can directly or indirectly interact with the session management network element. Wherein, the target RAN and the session management network element can exist intermediate nodes for transparently forwarding the messages between the target RAN and the session management network element, or the target RAN and the session management network element can also exist intermediate nodes for redirecting the messages sent by the target RAN to the session management network element to the session management network element.

[0256] 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, for example, the target access mobility management network element, and the embodiments of the present application do not make specific limitations thereon.

[0257] In a possible implementation, the target RAN sends the first indication information to the session management network element through an interface between the target RAN and the session management network element.

[0258] It can be understood that there is an interface between the target RAN and the session management network element, and the first indication information is sent by invoking a service operation provided by the interface. For example, in the distributed NAS architecture shown in FIG. 4, the target RAN can directly interact through a service interface between the target RAN and the session management network element, thereby avoiding centralized forwarding through the access mobility management network element and decoupling the session-related functions in the access mobility management network element.

[0259] That is, 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 improve flexibility.

[0260] It can be understood that the target RAN can also obtain the session management network element corresponding to each session of the plurality of 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.

[0261] In addition, the content indicated by the first indication information corresponding to different sessions can be different according to different contents indicated by the first indication information, which will be described below.

[0262] In a possible implementation, the first indication information is used to 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 first terminal.

[0263] That is, the target RAN indicates to the session management network element whether the first terminal is located in the allowed area indicated by the SAR information of the first terminal, so that the session management network element determines whether all non-urgent service sessions of the first terminal need to be deactivated or released according to whether the first terminal is located in the allowed area. In addition, the target RAN indicates to the session management network element corresponding to the i th session of the plurality of sessions of the first terminal whether the first terminal is located in the service area indicated by the service area information (such as LADN information) of the data network corresponding to the i th session, so that the session management network element determines whether the i th session needs to be deactivated or released according to whether the first terminal is located in the service area.

[0264] It should be understood that the target RAN sends the first indication information through the switching-related signaling, which will be described below.

[0265] In a possible implementation, the target RAN sends the first indication information to the session management network element, comprising: the target RAN sends the first indication information to the session management network element according to the first terminal not being in the allowed area indicated by the SAR information of the first terminal. The first indication information is used to indicate that the first terminal is not in the allowed area.

[0266] It can be understood that, since the first terminal is not in the allowed area indicated by the SAR information, the first terminal is not allowed to initiate non-emergency service in the service area of the target RAN.

[0267] That is, the target RAN can send the first indication information to the session management network element according to the first terminal not being in the allowed area indicated by the SAR information of the first terminal, so as to indicate that the first terminal is not in the allowed area, and further make the session management network element determine not to allow the establishment of the non-emergency service session of the first terminal, so that the session management can be reliably performed in the handover process in the case of decoupling the session-related function of the access mobility management network element.

[0268] In a possible implementation, the target RAN sends the first indication information to the session management network element, comprising: the target RAN sends 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 to deactivate or release the session of the first terminal, and the first request includes the first indication information.

[0269] The session management network element manages the session of the first terminal according to the first indication information (i.e., step S704), comprising: the session management network element deactivates or releases the session of the first terminal according to the first request.

[0270] It can be understood that, the first indication information can be explicitly indicated or implicitly indicated. For example, the target RAN requests the session management network element to deactivate or release the session of the first terminal, which implicitly indicates that the first terminal is not in the allowed area indicated by the SAR information.

[0271] That is, the target RAN can implicitly indicate that the first terminal is not in the allowed area indicated by the SAR information by requesting the session management network element to deactivate or release the session of the first terminal, so that the session management network element can deactivate or release the session of the first terminal according to the request.

[0272] In a possible implementation, the session of the first terminal is a session corresponding to non-emergency service; the target RAN sends the first request to the session management network element, comprising: the target RAN sends the first request to the session management network element according to the session of the first terminal being a session corresponding to non-emergency service.

[0273] That is, the target RAN can implicitly indicate that the first terminal is not in the allowed area indicated by the SAR information by requesting the session management network element to deactivate or release the session corresponding to the non-emergency service of the first terminal, so that the session management network element can deactivate or release the session corresponding to the non-emergency service of the first terminal according to the request, and avoid deactivating or releasing the session corresponding to the emergency service of the first terminal, thereby further guaranteeing that the session management can be reliably performed in the handover process in the case of decoupling the session-related functions of the access mobility management network element.

[0274] In a possible implementation, the first request includes a first cause value, and the first cause value is used to indicate that the reason for sending the first request is that the first terminal is not in the allowed area indicated by the SAR information of the first terminal.

[0275] That is, by indicating that the reason for deactivating or releasing the session of the first terminal is that the first terminal is not in the allowed area indicated by the SAR information of the first terminal through the first cause value, the session management network element can avoid attempting to establish the session of the first terminal again after deactivating or releasing the session of the first terminal, thereby further guaranteeing that the session management can be reliably performed in the handover process in the case of decoupling the session-related functions of the access mobility management network element.

[0276] In a possible implementation, the method shown in FIG. 7 further includes:

[0277] S705, the first terminal sends second indication information to the target RAN. Correspondingly, the target RAN receives the second indication information from the first terminal. The second indication information is used to indicate that the air interface handover is completed.

[0278] S706, the target RAN sends third indication information to the access mobility management network element according to that the first terminal is located in the allowed 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 indicate that the serving RAN of the first terminal is switched from the source RAN to the target RAN.

[0279] That is, the target RAN can send the handover-related indication (i.e., the third indication) to the access mobility management network element according to that the first terminal is located in the allowed area indicated by the SAR information, thereby notifying the access mobility management network element that the serving RAN of the first terminal is switched from the source RAN to the target RAN, so that the target RAN can send the handover-related indication to the session management network element and the access mobility management network element respectively, realize the decoupling of the functions between the SMF and the AMF, and enhance flexibility.

[0280] It can be understood that step S705 can be before step S701. In addition, there is no timing requirement between step S706 and step S703, for example, step S706 can be before or after step S703, or both can be executed at the same time, and the embodiments of the present application do not make specific limitations on this.

[0281] In a possible implementation, the target RAN sends the first indication information to the session management network element, comprising: the target RAN sends a second request to the session management network element, the second request being used to request to switch the service RAN of the first terminal from the source RAN to the target RAN, and the second request comprising the first indication information.

[0282] Correspondingly, the session management network element manages the session of the first terminal according to the first indication information (i.e., step S704), comprising: the session management network element performs session switching on the session of the first terminal according to the second request, and the session switching comprises updating the session management upper and lower service RAN of the first terminal from the source RAN to the target RAN.

[0283] It can be understood that the second request has a similar effect as the session modification request of step S203, or step S304, or step S314, which is used to request the session management network element to update the tunnel information and notify the corresponding user plane network element, which will not be described here.

[0284] In addition, in the case of sending the second request, the first indication information can 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, which will be described uniformly here and will not be described hereinafter.

[0285] That is, the target RAN can send the second request comprising the first indication information to the session management network element according to whether the first terminal is located in the allowed area indicated by the SAR information, and then the session management network element can perform session switching, or session deactivation or release on the session of the first terminal according to whether the first terminal is located in the allowed 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 session of the first terminal.

[0286] For example, the first indication information indicates that the first terminal is not in the allowed area indicated by the SAR information, and then the session management network element can deactivate or release the session of the first terminal according to the second request. For another example, it is assumed that the first indication information indicates that the first terminal is in the allowed area indicated by the SAR information, but is not in the service area indicated by the area information of the data network, and then the session management network element deactivates or releases the session corresponding to the non-urgent service of the first terminal according to the second request. For another example, it is assumed that the first indication information indicates that the first terminal is in the allowed area indicated by the SAR information, and is located in the service area indicated by the area information of the data network, and then the session management network element switches the session corresponding to the non-urgent service of the first terminal according to the second request.

[0287] In the embodiment of the application, the target RAN can determine whether the first terminal is located in the service area indicated by the service area information corresponding to the first terminal according to the location information of the first terminal and the service area information, and then the session management network element can be indicated by the first indication information, so that the session management network element can determine which session of the first terminal needs to be switched, or deactivated or released according to the first indication information. Therefore, the information transmission method provided by the embodiment of the application can guarantee reliable session management in the handover process in the case of decoupling the session-related functions of the AMF.

[0288] In addition, 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, and then the target RAN sends the signaling related to the handover to the access mobility management network element, it is not necessary to send the signaling related to the handover to the session management network element based on the information fed back by the access mobility management network element about whether the first terminal is located in the service area, so that the signaling related to the handover sent by the target RAN to the session management network element and the access mobility management network element has no timing requirement, which can better decouple the functions of the access mobility network element and the session management network element, and further enhance the flexibility.

[0289] Scheme 1-2:

[0290] It can be understood that the difference between scheme 1-2 and the above-mentioned scheme 1-1 is that in 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 (such as SAR information and / or LADN information) corresponding to the first terminal before the handover execution phase.

[0291] FIG. 8 is a flow diagram illustrating a second example of a method for information transmission. The method for information transmission is applicable to the scenario 1-2 shown in (a) of FIG. 6, and mainly involves the interaction among the source RAN, the target RAN, and the session management network element. As shown in FIG. 8, the method for information transmission includes the following steps.

[0292] S801. The source RAN acquires the service area information corresponding to the first terminal.

[0293] It can be understood that the implementation of step S801 can refer to the related description of step S701 about the source RAN acquiring the service area information, which will not be repeated here.

[0294] 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, which can refer to the related description of step S701, which will not be repeated here.

[0295] S802. During the process of switching the serving RAN of the first terminal from the source RAN to the target RAN, the source RAN determines first indication information according to the location information and the service area information of the first terminal. The first indication information is used to indicate whether the first terminal is located in the service area indicated by the service area information.

[0296] It can be understood that the implementation of step S802 can refer to step S702, which will not be repeated here.

[0297] S803. The source RAN sends the first indication information to the session management network element. Correspondingly, the session management network element receives the first indication information from the source RAN. The session management network element is used to manage the session of the first terminal.

[0298] S804. The session management network element manages the session of the first terminal according to the first indication information.

[0299] It can be understood that the session management network element can manage the session of the first terminal according to the first indication information in response to the second request sent by the target RAN during the execution phase of the N2 switching, which will not be repeated here.

[0300] The step S803 will be described below.

[0301] It can be understood 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, and the difference is that the session management network element is selected by the source RAN.

[0302] For example, the source RAN sends the first indication information to the session management network element through the interface between the source RAN and the session management network element.

[0303] It should be understood that the source RAN sending the first indication information to the session management network element can also multiplex the implementation of the target RAN sending the first indication information to the session management network element in the method shown in FIG. 7.

[0304] For example, the source RAN sending the first indication information to the session management network element includes: the source RAN sending the first indication information to the session management network element according to the first terminal not being in the allowed area indicated by the SAR information of the first terminal, the first indication information being used to indicate that the first terminal is not in the allowed area.

[0305] For another example, the source RAN sending the first indication information to the session management network element includes: the source RAN sending a third request to the session management network element, the third request being used to request to deactivate or release the session of the first terminal, the third request including the first indication information.

[0306] For another example, the session of the first terminal is a session corresponding to non-urgent service; the source RAN sending the third request to the session management network element includes: the source RAN sending the third request to the session management network element according to the session of the first terminal being the session corresponding to the non-urgent service.

[0307] It can be understood that the third request can also include a second cause value, the second cause value being 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, so that the session management network element can avoid attempting to establish the session of the first terminal again after deactivating or releasing the session of the first terminal.

[0308] For another example, the source RAN sending the first indication information to the session management network element includes: the source RAN sending a fourth request to the session management network element, the fourth request being used to request to prepare 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. Correspondingly, the session management network element managing the session of the first terminal according to the first indication information (i.e., step S704) includes: 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.

[0309] It can be understood that the above-mentioned modification of the user plane network element corresponding to the session of the first terminal can be referred to the above-mentioned related description of step S305 in FIG. 3, for example, in the preparation phase of N2 switching, the SMF can determine whether a new UPF (e.g., target UPF or I-UPF) is needed according to the session modification request (i.e., the above-mentioned fourth request) of step S304, and in the case of determining that the new UPF is not needed, modify the tunnel information related to the PSA-UPF.

[0310] The overall method flow corresponding to the above-mentioned scheme 1-1 and scheme 1-2 is introduced above, and the method shown in FIG. 7 and FIG. 8 is specifically introduced below taking Xn handover and N2 handover as examples.

[0311] For Xn handover:

[0312] FIG. 9 is a flow diagram of a method of information transmission provided by an embodiment of the present application. As shown in FIG. 9, the method of information transmission is applicable to the scheme 1-1 shown in (a) of FIG. 6, and mainly involves the interaction between a terminal (taking UE1 in FIG. 9 as an example), a source RAN, a target RAN, an access mobile management network element (taking AMF in FIG. 9 as an example), a session management network element (taking SMF in FIG. 9 as an example), and a user plane network element (taking UPF in FIG. 9 as an example). In addition, the flow shown in FIG. 9 mainly involves whether UE1 is located in the allowed area indicated by SAR information.

[0313] As shown in FIG. 9, the method of information transmission includes the following steps:

[0314] S901, In the process of UE1 registering the network, UE1 and the source RAN obtain SAR information.

[0315] It can be understood that UE1 registers to the network, and the AMF determines the SAR information of UE1 in the process of UE1 registering, and sends the SAR information to the source RAN and UE1.

[0316] S902, PDU session is established.

[0317] It can be understood that PDU session can be established between UE1 registering the network. In the process of UE1 establishing 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, which can be the multiplexed temporary identifier between UE1 and AMF, i.e. globally unique temporary UE identifier (GUTI).

[0318] S903, RAN handover is completed.

[0319] It can be understood that the specific implementation of step S903 can refer to the completion of RAN handover in step S201, for example, the source RAN decides to hand over UE1 to the target RAN, and then the air interface connection of UE is handed over from the source RAN to the target RAN, and the target RAN obtains the context information of UE1 from the source RAN through the Xn interface, including SMF1 / 2 corresponding to session 1 / 2, UE (temporary) identifier, SAR information, etc., which will not be described here.

[0320] In addition, after receiving the UE1 handover completion indication, the target RAN triggers step S904 and step S906. It should be understood that step S904 and step S906 have no timing requirements, and step S904 can be performed before or after step S906, or both, and the embodiments of the present application do not make specific limitations in this regard.

[0321] S904, the target RAN sends a first path switching request to the AMF. Correspondingly, the AMF receives the first path switching request from the target RAN.

[0322] It can be understood that the first path switching request can include a temporary identifier of UE1, and a TA, and / or a target RAN or cell identifier. In addition, the specific implementation of step S904 can refer to the related description of the third indication information in FIG. 7, which will not be repeated here.

[0323] S905, the AMF sends a first path switching response to the target RAN. Correspondingly, the target RAN receives the first path switching response from the AMF.

[0324] It can be understood that the first path switching response can be used to indicate that the first path switching request is received.

[0325] S906, the target RAN sends a second path switching request to the SMF. Correspondingly, the SMF receives the second path switching request from the target RAN.

[0326] It can be understood that the target RAN determines whether UE1 is in the allowed area indicated by the SAR information of UE1 according to the location of UE1 and the SAR information of UE1, that is, whether the TA where UE1 is currently located is in the restricted area.

[0327] In addition, the second path switching request includes a UE1 (temporary) identifier, a PDU session identifier, and an indication of whether UE1 is located in the allowed area indicated by the SAR information.

[0328] Optionally, the second path switching request can also include the status of the established QoS flow, the PDU session identifier and failure reason of the handover failure, and the access side tunnel information corresponding to each PDU session.

[0329] S907, the N4 session modification process is completed between the SMF and the UPF.

[0330] It can be understood that the specific implementation of step S907 can refer to steps S204 and S205 of the foregoing FIG. 2, which will not be repeated here.

[0331] S908, the SMF sends a second path switching response to the target RAN. Correspondingly, the target RAN receives the second path switching response from the SMF.

[0332] FIG. 10 is a flow diagram of a method of information transmission according to an embodiment of the present application. As shown in FIG. 10, the difference between the method of information transmission shown in FIG. 10 and the method flow shown in FIG. 9 is that the method shown in FIG. 10 mainly involves whether UE1 is located in the service area indicated by the LADN information.

[0333] As shown in FIG. 10, the method of information transmission includes the following steps: S1001-S1009, wherein S1002-S1006 are the same as steps S901-S905, and S1008-S1009 are the same as steps S907-S908.

[0334] S1001, the AMF sends the LADN information to the source RAN and / or the target RAN.

[0335] It can be understood that, after the RAN (including the source RAN and the target RAN) is registered to 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 the AMF or report the information of the RAN, the AMF sends the LADN information to the RAN; or, after UE1 establishes a PDU session, the core network (for example, the AMF, or the SMF, or other NFs) sends the LADN information corresponding to the DN of the PDU session to the RAN; or, the LADN information is pre-configured on the RAN.

[0336] S1007, the target RAN sends a second path switching request to the SMF. Correspondingly, the SMF receives the second path switching request from the target RAN.

[0337] It can be understood that the difference between step S1007 and step S906 before step S906 is that the second path switching request in step S1007 includes an indication of whether UE1 is located in the service area indicated by the LADN information corresponding to the PDU session of UE1.

[0338] It should be understood that, since the judgment factors of 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 are two independent judgment factors, FIG. 9 and FIG. 10 can be combined, that is, the source RAN determines whether the UE is located in the allowed area indicated by the SAR information, and the target RAN determines whether the UE is located in the service area indicated by the LADN information.

[0339] For N2 handover:

[0340] FIG. 11 is a flowchart illustrating a method of information transmission according to an embodiment of the present application. As shown in FIG. 11, the method of information transmission is applicable to the scenario 1-2 shown in (a) of FIG. 6, and mainly involves the interaction between a terminal (e.g., UE1 in FIG. 11), a source RAN, a target RAN, a source access and mobility management network element (e.g., source AMF in FIG. 11), a target access and mobility management network element (e.g., target AMF in FIG. 11), a session management network element (e.g., SMF in FIG. 11), and an NRF. In addition, the flow shown in FIG. 11 mainly involves that, in 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.

[0341] As shown in FIG. 11, the method of information transmission includes the following steps.

[0342] S1100. The source RAN obtains the location information of the target RAN from the NRF.

[0343] It can be understood that, in the case where the source RAN does not know the location (i.e., the TA corresponding to the target RAN) of the target RAN, the source RAN can send a query request to the NRF, and thus receive the location of the target RAN from the NRF. The query request can include the identifier of the target cell or the target RAN.

[0344] In addition, the source RAN can also be preconfigured with the locations (e.g., TAs) corresponding to different cell or RAN identifiers, i.e., step S1100 is optional.

[0345] S1101. The source RAN determines whether UE1 is located in the service area indicated by the LADN information.

[0346] It can be understood that, according to the related description of step S1001 of the foregoing FIG. 10, the source RAN can obtain the LADN information.

[0347] In addition, when the source RAN decides to hand over UE1 from the source RAN to the target RAN, the source RAN can determine, according to the location of the target RAN or the target cell, whether each PDU session of UE1 is in the service area indicated by the LADN information after the handover of UE1, i.e., whether the TA where UE1 is located after the handover is in the service area indicated by the LADN information.

[0348] S1102. The source RAN sends a handover requirement to the source AMF. Accordingly, the source AMF receives the handover requirement from the source RAN.

[0349] It can be understood that the specific implementation of step S1102 can refer to step S301, which will not be described here again.

[0350] S1103. The source AMF selects a target AMF.

[0351] It can be understood that the specific implementation of step S1103 can refer to step S302, and details are not described here.

[0352] S1104. The source AMF sends a UE context setup request to the target AMF. Accordingly, the target AMF receives the UE context setup request from the source AMF.

[0353] S1105. The source RAN sends a third path switch request to the SMF. Accordingly, the SMF receives the third path switch request from the source RAN.

[0354] It can be understood that the third path switch request in step S1105 is used to request to prepare to switch the service RAN of UE1 from the source RAN to the target RAN, and the third path switch request includes the indication information indicating whether UE1 is located in the service area indicated by the LADN information.

[0355] The difference between the content included in the third path switch request and the content included in the second path switch request in the foregoing step S1007 is that the third path switch request further includes an identifier of the target RAN.

[0356] It can be understood that step S1105 can trigger the SMF to perform session management, i.e., the session management in step S305. For example, the SMF can determine whether to insert / remove a UPF, update a session context, and the like.

[0357] It should be understood that step S1105 has no time sequence requirement with steps S1102-S1104, for example, step S1105 can be performed before or after step S1104, or both are performed at the same time, and the embodiments of the present application do not make specific limitations on this.

[0358] S1106. The SMF sends a switch indication to the target RAN. Accordingly, the target RAN receives the switch indication from the SMF. The switch indication includes UPF N3 tunnel information, or a temporary identifier of the UE between the SMF and the target RAN, and the like, which is not specifically limited by the embodiments of the present application.

[0359] It can be understood that after the target AMF receives the UE context setup request in step S1104, the target AMF will send a switch request to the target RAN, which can be specifically referred to step S307 of FIG. 3, and details are not described here.

[0360] FIG. 12 is a flow diagram of another information transmission method according to an embodiment of the present application. As shown in FIG. 12, the information transmission method differs from the method shown in FIG. 11 in that the method shown in FIG. 12 mainly involves sending, by the target RAN, indication information indicating whether the UE 1 is located in the service area indicated by the LADN information to the SMF in the execution stage.

[0361] As shown in FIG. 12, the information transmission method includes the following steps: S1200-S1215, wherein the step S1200 is the same as the step S1100.

[0362] S1201, the source RAN sends the handover requirement to the source AMF. Accordingly, the source AMF receives the handover requirement from the source RAN.

[0363] It can be understood that the step S1201 differs from the step S1102 in that the handover requirement of the step S1201 can include the LADN information, and thus the source AMF can send the LADN information to the target RAN through the step S1201, so as to determine whether the UE 1 is located in the service area indicated by the LADN information in the execution stage.

[0364] S1202, the source AMF selects the target AMF.

[0365] S1203, the source AMF sends the UE context setup request to the target AMF. Accordingly, the target AMF receives the UE context setup request from the source AMF.

[0366] It should be understood that the UE context setup request in the step S1203 includes the LADN information.

[0367] S1204, the source RAN sends the third-path handover request to the SMF. Accordingly, the SMF receives the third-path handover request from the source RAN.

[0368] It can be understood that the third-path handover request of the step S1204 does not include the indication information indicating whether the UE 1 is located in the service area indicated by the LADN information.

[0369] S1205, the SMF sends the handover indication to the target RAN. Accordingly, the target RAN receives the handover indication from the SMF.

[0370] S1206, the target AMF sends the handover request to the target RAN. Accordingly, the target RAN receives the handover request from the target AMF.

[0371] It can be understood that the handover request of the step S1206 is similar to the handover request of the step S307 of FIG. 3, which will not be described here.

[0372] In addition, the handover request of step S1206 can comprise the LADN information and the temporary identifier of UE1 between the target AMF and the target RAN.

[0373] S1207, the target RAN sends a handover request acknowledgement to the target AMF. Accordingly, the target AMF receives the handover request acknowledgement from the target RAN.

[0374] The execution phase is introduced below.

[0375] S1208, the source AMF sends a handover command to the source RAN. Accordingly, the source RAN receives the handover command from the source AMF.

[0376] It can be understood that the handover command of step S1208 has the same effect as the handover command of S312 of FIG. 3, and the difference is that the handover command of step S1208 comprises the temporary identifier of UE1.

[0377] S1209, the source RAN sends a handover command to UE1. Accordingly, UE1 receives the handover command from the source RAN.

[0378] S1210, the RAN handover is completed.

[0379] S1211, the target RAN sends a handover notification to the target AMF. Accordingly, the target AMF receives the handover notification from the target RAN.

[0380] It can be understood that the handover notification of step S1211 has the same effect as the handover notification of S313 of FIG. 3, and the difference is that the handover notification of step S1211 comprises the temporary identifier of UE1.

[0381] S1212, the target RAN determines whether UE1 is located in the service area indicated by the LADN information.

[0382] 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.

[0383] It can be understood that the specific implementation of step S1213 can refer to step S1007, which will not be described here.

[0384] It should be understood that there is no timing requirement between step S1213 and step S1211, for example, S1214 can be executed before or after step S1211, or both.

[0385] S1214, the N4 session modification procedure is completed between the SMF and the UPF.

[0386] It can be understood that the specific implementation of step S1214 can refer to step S907, which will not be described here.

[0387] S1215, the SMF sends a second path switching response to the target RAN. Accordingly, the target RAN receives the second path switching response from the SMF.

[0388] It can be understood that the specific implementation of step S1215 can refer to step S908, and details are not described here.

[0389] FIG. 13 is a flow diagram of an information transmission method according to an embodiment of the present application. As shown in FIG. 13, the information transmission method differs from the method flow shown in FIG. 11 and the method flow shown in FIG. 12 in that the method flow shown in FIG. 13 is used to send indication information indicating whether UE1 is located in the allowed area indicated by the SAR information to the SMF.

[0390] As shown in FIG. 13, the information transmission method includes the following steps: S1300-S1316, wherein step S1300 is the same as step S1100.

[0391] S1301, the source RAN determines whether UE1 is located in the allowed area indicated by the SAR information.

[0392] It can be understood that according to the related description of step S901 of the foregoing FIG. 9, the source RAN can obtain the SAR information.

[0393] In addition, when the source RAN decides to switch UE1 from the source RAN to the target RAN, the source RAN can judge UE1 according to the location of the target RAN or the target cell, and further determine whether UE1 is in the allowed area indicated by the SAR information after switching, that is, whether the TA where UE1 is located after switching is in the allowed area indicated by the SAR information.

[0394] S1302, the source RAN sends a switching requirement to the source AMF. Accordingly, the source AMF receives the switching requirement from the source RAN.

[0395] It can be understood that the specific implementation of step S1302 can refer to step S301, and details are not described here.

[0396] S1303, the source AMF selects a target AMF.

[0397] It can be understood that the specific implementation of step S1303 can refer to step S302, and details are not described here.

[0398] S1304, the source AMF sends a UE context setup request to the target AMF. Accordingly, the target AMF receives the UE context setup request from the source AMF.

[0399] S1305. The source RAN sends a third path switching request to the SMF. Accordingly, the SMF receives the third path switching request from the source RAN.

[0400] It can be 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 the UE 1 is located in the allowed area indicated by the SAR information.

[0401] It should be understood that step S1305 has no timing requirement with steps S1302-S1304, for example, step S1305 can be performed before or after step S1304, or both, and the embodiments of the present application do not make specific limitations on this.

[0402] S1306. The SMF sends a switching indication to the target RAN. Accordingly, the target RAN receives the switching indication from the SMF.

[0403] It can be understood that the switching indication in step S1306 can refer to the switching indication in step S1106, which will not be described here.

[0404] FIG. 14 is a flow diagram of an information transmission method according to an embodiment of the present application. As shown in FIG. 14, the difference between the information transmission method and the method flow shown in FIG. 13 is that in the method flow shown in FIG. 14, the target RAN sends the indication information indicating whether the UE 1 is located in the allowed area indicated by the SAR information to the SMF.

[0405] As shown in FIG. 14, the information transmission method includes the following steps: S1400-S1408, wherein step S1400 is the same as step S1300, which will not be described here.

[0406] S1401. The source RAN sends a switching requirement to the source AMF. Accordingly, the source AMF receives the switching requirement from the source RAN.

[0407] It can be understood that the difference between the switching requirement in step S1401 and the switching requirement in step S1201 is that the switching requirement in step S1401 includes the SAR information.

[0408] S1402. The source AMF selects a target AMF.

[0409] S1403. The source AMF sends a UE context setup request to the target AMF. Accordingly, the target AMF receives the UE context setup request from the source AMF.

[0410] It should be understood that the UE context setup request in step S1403 includes the SAR information.

[0411] S1404, the target AMF sends a handover request to the target RAN. Accordingly, the target RAN receives the handover request from the target AMF.

[0412] It can be understood that the difference between the handover request of step S1404 and the handover request in step S1206 is that the handover request in step S1404 includes the SAR information.

[0413] S1405, the target RAN sends a handover request acknowledgement to the target AMF. Accordingly, the target AMF receives the handover request acknowledgement from the target RAN.

[0414] S1406, the target RAN determines whether UE1 is located in the allowed area indicated by the SAR information.

[0415] 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.

[0416] It can be understood that the third-path handover request of step S1407 can refer to the third-path handover request of step S1305, which will not be described here.

[0417] S1408, the SMF sends a handover indication to the target RAN. Accordingly, the target RAN receives the handover indication from the SMF.

[0418] It can be understood that the specific implementation of step S1408 can refer to step S1306, which will not be described here.

[0419] It should be understood that the method flows shown in the above Figs. 11-14 can be combined, and the embodiments of the present application do not make specific limitations thereon.

[0420] For example, the indication information sent by the source RAN in Fig. 11 to the SMF for indicating whether UE1 is located in the service area indicated by the LADN information can be combined with the indication information sent by the target RAN in Fig. 14 to the SMF for indicating whether UE1 is located in the allowed area indicated by the SAR information. For another example, the indication information sent by the target RAN in Fig. 12 to the SMF for indicating whether UE1 is located in the service area indicated by the LADN information in the execution phase can be combined with the indication information sent by the source RAN in Fig. 13 to the SMF for indicating whether UE1 is located in the allowed area indicated by the SAR information in the preparation phase.

[0421] The following introduces scheme 2.

[0422] FIG. 15 is a schematic flowchart of a method of information transmission according to an embodiment of the present application. The method of information transmission is applicable to the scenario 2 shown in (b) of FIG. 6, and mainly involves the interaction among the source RAN, the target RAN, and the session management network element. As shown in FIG. 15, the method of information transmission includes the following steps.

[0423] S1501. The session management network element acquires the service area information corresponding to the first terminal.

[0424] It can be understood that the session management network element can acquire the service area information from a 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.

[0425] In addition, as described above in relation to the method flow shown in FIG. 7, the service area information can include the SAR information and the LADN information, which will not be described herein again.

[0426] S1502. During the process of switching the serving RAN of the first terminal 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. Correspondingly, the session management network element receives the first request from the source RAN or the target RAN.

[0427] The first request is used to request to switch 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.

[0428] It should be understood that the difference between step S1502 and the aforementioned scenario 1 is that the SMF can determine whether the first terminal is located in the service area indicated by the service area information according to the location information of the first terminal and the service area information, and does not need the source RAN or the target RAN to send the indication information indicating whether the first terminal is located in the service area indicated by the service area information.

[0429] S1503. The session management network element manages the session of the first terminal according to whether the first terminal is located in the service area indicated by the service area information.

[0430] It can be understood that the specific implementation of step S1503 can refer to step S704 or step S804, which will not be described herein again.

[0431] Since in the embodiment of the application, the session management network element obtains the service area information corresponding to the first terminal, and then in the process of switching the service RAN of the first terminal from the source RAN to the target RAN, the session management network element can determine whether the first terminal is located in the service area indicated by the service area information according to the location information of the first terminal and the service area information in response to the first request sent by the source RAN or the target RAN, so as to determine which sessions of the first terminal need to be switched, or deactivated or released. Therefore, the scheme 2 provided in the embodiment of the application can guarantee reliable session management in the switching process in the case of decoupling the session-related functions of the AMF.

[0432] 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 request about the switching from the target RAN, the signaling about the switching sent by the target RAN to the session management network element and the access mobile management network element respectively has no timing requirement, so that the functions of the access mobile network element and the session management network element can be better decoupled, and the flexibility is further enhanced.

[0433] The above introduces the overall method flow corresponding to the above-mentioned scheme 2, and the method shown in FIG. 15 is specifically introduced below by taking Xn switching as an example.

[0434] FIG. 16 is a flowchart of an information transmission method according to an embodiment of the application. As shown in FIG. 16, the information transmission method mainly involves the interaction between UE1, the source RAN, the target RAN, the AMF, the SMF, and the UDM / UDR. In addition, FIG. 16 involves the SMF determining whether UE1 is located in the allowed area indicated by the SAR information.

[0435] As shown in FIG. 16, the information transmission method includes the following steps:

[0436] S1601, establishing a PDU session.

[0437] It can be understood that in the PDU session establishment process of UE1, the source RAN can select the SMF according to the parameters of the session, and send a session establishment request to the SMF.

[0438] Optionally, the source RAN can carry the SAR information of the UE.

[0439] S1601a, the source RAN sends a session establishment request to the SMF. Correspondingly, the SMF receives the session establishment request from the source RAN.

[0440] It can be understood that the session establishment request can include the information of the SAR.

[0441] In addition, if the SMF does not have the SAR information of the UE, the SMF can obtain the SAR information from the UDM or the UDR.

[0442] Optionally, the method shown in FIG. 16 further includes:

[0443] S1601b, the SMF obtains the SAR information of UE1 from the UDM or the UDR.

[0444] It can be understood that the SMF can obtain the subscription information of UE1 from the UDR, and then can 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 the handover request from the target RAN, the SMF can request the SAR information of UE1 from the target RAN.

[0445] S1602, the RAN completes the handover.

[0446] It can be understood that the specific implementation of step S1602 can be referred to step S903, and details are not described here.

[0447] In addition, after the target RAN receives the indication information indicating the completion of the handover from UE1 in step S1602, the target RAN can trigger the execution of step S1603 and step S1605.

[0448] S1603, 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.

[0449] It can be understood that the specific implementation of step S1603 can be referred to step S904, and details are not described here.

[0450] 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.

[0451] It can be understood that the specific implementation of step S1604 can be referred to step S905, and details are not described here.

[0452] 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.

[0453] It can be understood that step S1605 is similar to step S906, and the difference between the two is that the second path handover request in step S1605 does not include indication information indicating whether UE1 is located in the allowed area indicated by the SAR information.

[0454] In addition, the second path switching request can comprise location information of the UE1, for example, a cell or an identity of the target RAN, or a TA in which the UE1 is located.

[0455] S1606, the SMF determines whether the UE1 is located in the allowed area indicated by the SAR information according to the location information of the UE1 and the SAR information.

[0456] S1607, the SMF determines to perform session switching, or session deactivation or release according to whether the UE1 is located in the allowed area indicated by the SAR information.

[0457] S1608, the SMF and the UPF complete the N4 session modification procedure.

[0458] S1609, the SMF sends a second path switching response to the target RAN. Correspondingly, the target RAN receives the second path switching response from the SMF.

[0459] FIG. 17 is a flowchart of another information transmission method according to an embodiment of the present application. As shown in FIG. 17, the difference between the method flowchart shown in FIG. 17 and the method flowchart shown in FIG. 16 is that the SMF determines whether the UE1 is located in the service area indicated by the LADN information.

[0460] As shown in FIG. 17, the information transmission method comprises the following steps.

[0461] S1701, a PDU session is established.

[0462] It can be understood that the specific implementation of step S1701 can refer to step S1601, which will not be described here.

[0463] S1701a, the source RAN sends a session establishment request to the SMF. Correspondingly, the SMF receives the session establishment request from the source RAN.

[0464] It can be understood that the SMF can be preconfigured with LADN information.

[0465] In addition, if the SMF does not have LADN information, the SMF can request the UDR for LADN information of the DN corresponding to the PDU session.

[0466] S1702, the RAN handover is completed.

[0467] It can be understood that the specific implementation of step S1702 can refer to step S903, which will not be described here.

[0468] In addition, after the target RAN receives the indication information from the UE1 for indicating that the handover is completed in step S1702, the target RAN can trigger the execution of step S1604 and step S1606.

[0469] S1703, the target RAN sends a first path switching request to the AMF. Accordingly, the AMF receives the first path switching request from the target RAN.

[0470] It can be understood that the specific implementation of step S1703 can be referred to step S904, and details are not described here.

[0471] S1704, the AMF sends a first path switching response to the target RAN. Accordingly, the target RAN receives the first path switching response from the AMF.

[0472] It can be understood that the specific implementation of step S1704 can be referred to step S905, and details are not described here.

[0473] S1705, the target RAN sends a second path switching request to the SMF. Accordingly, the SMF receives the second path switching request from the target RAN.

[0474] It can be understood that step S1705 is similar to step S906, and the difference between the two is 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.

[0475] In addition, the second path switching request can include the location information of UE1, such as the cell or identity of the target RAN, or the TA where UE1 is located.

[0476] S1706, the SMF determines whether UE1 is located in the service area indicated by the LADN information according to the location information of UE1 and the LADN information.

[0477] S1707, the SMF determines to perform session switching, or session deactivation or release according to whether UE1 is located in the service area indicated by the LADN information.

[0478] S1708, the N4 session modification procedure is completed between the SMF and the UPF.

[0479] S1709, the SMF sends a second path switching response to the target RAN. Accordingly, the target RAN receives the second path switching response from the SMF.

[0480] It can be understood that the above-mentioned 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 policy of the AMF) and indicating to the SMF; the SMF can be responsible for determining whether the terminal is located in the service area indicated by the LADN information, which can better decouple the AMF and the SMF.

[0481] The following illustrates the method flow combined between the above-mentioned scheme 1 and scheme 2.

[0482] FIG. 18 is a schematic diagram of an information transmission method flow provided by an embodiment of the present application. As shown in FIG. 18, the information method is exemplarily illustrated by taking Xn handover as an example, and mainly involves the interaction between UE1, a source RAN, a target RAN, an AMF, an SMF, and a UPF.

[0483] As shown in FIG. 18, the information transmission method includes the following steps.

[0484] S1801, in the process of registering the network, UE1 and the source RAN acquire SAR information.

[0485] It can be understood that the specific implementation of step S1801 can be referred to step S901, and details are not described herein again.

[0486] S1802, a PDU session is established.

[0487] It can be understood that the specific implementation of step S1802 can be referred to step S902, and details are not described herein again.

[0488] S1803, RAN handover is completed.

[0489] It can be understood that the specific implementation of step S1803 can be referred to step S903, and details are not described herein again.

[0490] S1804, 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.

[0491] It can be understood that the specific implementation of step S1804 can be referred to step S904, and details are not described herein again.

[0492] 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.

[0493] It can be understood that the specific implementation of step S1805 can be referred to step S905, and details are not described herein again.

[0494] 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.

[0495] It should be understood that step S1806 can be the same as step S906, or step S1806 can further include LADN information, for the SMF to determine whether UE1 is located in the service area indicated by the LADN information.

[0496] S1807, the SMF determines whether the UE1 is located in the service area indicated by the LADN information according to the location information of the UE1 and the LADN information.

[0497] S1808, the SMF determines to perform session switching, or session deactivation or release according to whether the UE1 is located in the allowed area indicated by the SAR information and whether the UE1 is located in the service area indicated by the LADN information in the second path switching request.

[0498] S1809, the N4 session modification procedure is completed between the SMF and the UPF.

[0499] S1810, the SMF sends a second path switching response to the target RAN. Correspondingly, the target RAN receives the second path switching response from the SMF.

[0500] The following introduces scheme 3.

[0501] FIG. 19 is a flow diagram of an information transmission method provided by an embodiment of the application. The information transmission method is applicable to scheme 3 shown in (c) in FIG. 6, and mainly involves the interaction between the source RAN, the target RAN, and the session management network element. As shown in FIG. 19, the information transmission method includes the following steps.

[0502] S1901, in the process of switching the serving RAN of the first terminal from the source RAN to the target RAN, the target RAN sends third indication information to the access mobility management network element. Correspondingly, the access mobility management network element receives the third indication information from the target RAN.

[0503] The third indication information is used to indicate that the serving RAN of the first terminal is switched from the source RAN to the target RAN.

[0504] It can be understood that the specific implementation of step S1901 can be referred to step S706, which will not be described here.

[0505] S1902, the access mobility management network element determines first indication information according to 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 in the service area indicated by the service area information.

[0506] It can be understood that the specific implementation of step S1902 can be referred to step S702 or step S802, which will not be described here.

[0507] S1903, the access mobility management network element sends the first indication information to the target RAN or the data management network element. Correspondingly, the target RAN or the data management network element receives the first indication information from the access mobility management network element.

[0508] The target RAN or the data management network element is configured to provide first indication information to the session management network element, and the session management network element is configured to manage the session of the first terminal.

[0509] It can be understood that the data management network element may, for example, be the UDM or the UDR in FIG. 1, and embodiments of the present application do not make specific limitations thereto.

[0510] It should be understood that the target RAN may, in the handover process of the first terminal, send the first indication information to the session management network element. Alternatively, the session management network element may, in the case of receiving a handover request from the source RAN or the target RAN, obtain the first indication information from the data management network element, and embodiments of the present application do not make specific limitations thereto.

[0511] In the embodiments of the present application, the access mobility management network element may, in response to the third indication information (which may, for example, be carried by signaling related to handover) sent by the target RAN, determine whether the first terminal is located in the service area indicated by the service area information corresponding to the first terminal according to the location of the first terminal and the service area information corresponding to the first terminal, and deliver the information (the first indication information) to the target RAN or the data management network element, so that the first indication information can be delivered to the session management network element through the target RAN or the data management network element, thereby enabling the session management network element to determine which sessions of the first terminal need to be handed over, or deactivated or released according to the first indication information. Therefore, the scheme 3 provided in the embodiments of the present application can guarantee reliable session management in the handover process in the case of decoupling the session-related functions of the AMF

[0512] The method flow process shown in FIG. 19 will be further described below taking Xn handover as an example.

[0513] FIG. 20 is a flowchart of an information transmission method according to an embodiment of the present application. As shown in FIG. 20, the information transmission method is similar to the method flow shown in FIG. 9, and the difference lies in that the information element 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.

[0514] As shown in FIG. 20, the information transmission method includes the following steps: S2001-S2008, S2001-S2004 are the same as steps S901-S904, and S2006-S2008 are the same as steps S906-S908, which will not be described herein again.

[0515] 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.

[0516] The first path switching response includes first indication information, and the first indication information indicates whether the UE 1 is located in the allowed area indicated by the SAR information and / or whether the UE 1 is located in the service area indicated by the LADN information.

[0517] FIG. 21 is a flowchart of a method of information transmission according to an embodiment of the present application. As shown in FIG. 21, the method of information transmission is different from the method shown in FIG. 20 in that after determining the first indication information, the AMF sends the first indication information to the UDR, so that the SMF can obtain the first indication information from the UDR.

[0518] As shown in FIG. 21, the method of information transmission includes the following steps: S2101-S2109, and S2101-S2103 are the same as S2002-S2004, which will not be repeated here.

[0519] S2104, the AMF sends the first indication information to the UDR. Correspondingly, the UDR receives the first indication information from the AMF.

[0520] It can be understood that the AMF can determine the first indication information according to the location information of the UE 1 included in the first path switching request and the SAR information and / or the LADN information, that is, whether the UE 1 is located in the allowed area indicated by the SAR information and / or whether the UE 1 is located in the service area indicated by the LADN information.

[0521] S2105, the AMF sends the first path switching response to the target RAN. Correspondingly, the target RAN receives the first path switching response from the AMF.

[0522] S2106, the target RAN sends a second path switching request to the SMF. Correspondingly, the SMF receives the second path switching request from the target RAN.

[0523] It should be understood that the second path switching request of step S2106 can not include the location information of the UE 1 and / or the service area information (for example, the SAR information and / or the LADN information).

[0524] S2107, the SMF obtains the first indication information from the UDR.

[0525] It can be understood that the SMF can subscribe to the status of U1 in the service area by the UDR, so as to obtain the first indication information in the case that the location of the UE 1 changes. In addition, if the status of the UE 1 in the service area does not change, the SMF can determine to perform session switching or session deactivation or release according to whether the UE 1 is located in the allowed area indicated by the SAR information and / or whether the UE 1 is located in the service area indicated by the LADN information.

[0526] Optionally, step S2107 comprises:

[0527] S2107a, the SMF sends a subscription request to the UDR. Accordingly, the UDR receives the subscription request from the SMF. Wherein, the subscription request is used to subscribe the status of the UE1 in the service area.

[0528] S2107b, in case that the status of the UE1 in the service area changes, the UDR sends a notification message to the SMF. Accordingly, the SMF receives the notification message from the UDR. Wherein, the notification message comprises the first indication information.

[0529] Alternatively, optionally, step S2107 comprises:

[0530] S2107c, the SMF sends a query request to the UDR in response to the second path switching request. Accordingly, the UDR receives the query request from the SMF.

[0531] S2107d, the UDR sends a query response to the SMF. Accordingly, the SMF receives the query response from the UDR. Wherein, the query response comprises the first indication information.

[0532] It can be understood that the SMF can send the query request to the UDR, and then query the status of the UE1 in the service area in the UDR, and then obtain the first indication information.

[0533] S2108, the SMF completes the N4 session modification procedure with the UPF according to the first indication information.

[0534] S2109, the SMF sends a second path switching response to the target RAN. Accordingly, the target RAN receives the second path switching response from the SMF.

[0535] The above describes the scheme provided by the embodiments of the present application mainly from the perspective of interaction between network elements. Correspondingly, the embodiments of the present application also provide a communication apparatus for implementing the above methods. The communication apparatus can be the target RAN, the source RAN, the session management network element, or the access mobile management network element in the above method embodiments, or a device containing the target RAN, the source RAN, the session management network element, or the access mobile management network element, or a component that can be used for the target RAN, the source RAN, the session management network element, or the access mobile management network element. It can be understood that, in order to implement the above functions, the communication apparatus contains the corresponding hardware structure and / or software module for executing each function. Those skilled in the art should easily realize that, in combination with the units and algorithm steps of the examples described in the embodiments disclosed herein, the present application can be realized in the form of hardware or a combination of hardware and computer software. Whether a certain function is realized in the form of hardware or 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 the present application.

[0536] The embodiments of the present application can divide the function modules of the communication apparatus according to the above method embodiments, for example, each function module can be divided according to each function, or two or more functions can be integrated in one processing module. The above integrated module can be realized in the form of hardware or software function module. It should be noted that the division of the modules in the embodiments of the present application is illustrative, and is only a logical function division. Actual implementation can have another division manner.

[0537] Taking the communication apparatus as the target RAN, the source RAN, the session management network element, or the access mobile management network element in the above method embodiments, FIG. 22 is a structure schematic diagram of a communication apparatus provided by the embodiments of the present application. As shown in FIG. 22, the communication apparatus 2200 includes a processing module 2201 and a transceiver module 2202. The processing module 2201 is configured to perform the processing functions of the target RAN, the source RAN, the session management network element, or the access mobile management network element in the above method embodiments. The transceiver module 2202 is configured to perform the transceiving functions of the target RAN, the source RAN, the session management network element, or the access mobile management network element in the above method embodiments.

[0538] The above method embodiments involve all related contents of each step, which can be referred to the function description of the corresponding function module, and will not be repeated here.

[0539] Since the communication apparatus 2200 provided by the embodiments of the present application can perform the above information transmission method, the technical effects that can be obtained thereby can be referred to the above method embodiments, and will not be repeated here.

[0540] In a possible design, the transceiver module 2202 can include a receiving module and a sending module (not shown in FIG. 22). The transceiver module is configured to implement the sending function and the receiving function of the communication apparatus 2200.

[0541] In a possible design, the communication apparatus 2200 can further include a storage module (not shown in FIG. 22), which stores programs or instructions. When the processing module 2201 executes the programs or instructions, the communication apparatus 2200 can perform the functions of the target RAN, the source RAN, the session management network element, or the access mobile management network element in any of the methods shown in FIGS. 7 to 21.

[0542] It should be understood that the processing module 2201 involved in the communication apparatus 2200 can be implemented by a processor or processor-related circuit component, and can be a processor or processing unit; and the transceiver module 2202 can be implemented by a transceiver or transceiver-related circuit component, and can be a transceiver or transceiving unit.

[0543] For example, FIG. 23 is a structural schematic of another communication apparatus provided by the embodiments of the present application. The communication apparatus can be a target RAN, a source RAN, a session management network element, or an access mobile management network element, or can be a chip (system) or other components or elements that can be arranged in the target RAN, the source RAN, the session management network element, or the access mobile management network element. As shown in FIG. 23, the communication apparatus 2300 can include a processor 2301. In a possible design, the communication apparatus 2300 can further include a memory 2302 and / or a transceiver 2303. The processor 2301 is coupled with the memory 2302 and the transceiver 2303, for example, through a communication bus.

[0544] The components of the communication apparatus 2300 will be described in detail below in combination with FIG. 23:

[0545] The processor 2301 is the control center of the communication apparatus 2300, and can be one processor or a plurality of 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 one or more embodiments of the present application, for example, one or more digital signal processors (DSPs), or one or more field programmable gate arrays (FPGAs).

[0546] In a possible design, the processor 2301 can execute 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.

[0547] In a specific implementation, as an example, the processor 2301 can include one or more CPUs, for example, the CPU0 and the CPU1 shown in FIG. 23.

[0548] In a specific implementation, as an example, the communication device 2300 can also include multiple processors, for example, the processor 2301 and the processor 2304 shown in FIG. 23. Each of the processors can be a single-CPU or a multi-CPU. The processor herein can refer to one or more devices, circuits, and / or processing cores for processing data (for example, computer program instructions).

[0549] The memory 2302 is configured to store software programs for implementing the solutions of the present application, and the processor 2301 is configured to control execution. For details, refer to the foregoing method embodiments, which will not be described here.

[0550] In a possible design, the memory 2302 can be a read-only memory (ROM) or other type of static storage device that can store static information and instructions, a random access memory (RAM) or other type of dynamic storage device that can store information and instructions, an electrically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM) or other optical disk storage, a magneto-optical disk, a magnetic disk storage or other magnetic storage device, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer, but is not limited to this. The memory 2302 can be integrated with the processor 2301, or can exist independently and be coupled to the processor 2301, and the embodiments of the present application are not limited in this regard.

[0551] The transceiver 2303 is configured to communicate with other communication devices. For example, the communication device 2300 is a target RAN, and the transceiver 2303 can be configured to communicate with a source RAN or a session management network element. For another example, the communication device 2300 is a source RAN, and the transceiver 2303 can be configured to communicate with a target RAN or a session management network element.

[0552] In a possible design, the transceiver 2303 can include a receiver and a transmitter (not shown separately in FIG. 23). The receiver is configured to implement the receiving function, and the transmitter is configured to implement the transmitting function.

[0553] In a possible design, the transceiver 2303 can be an input / output interface or an interface circuit, configured to input and / or output a signal.

[0554] In a possible design, the transceiver 2303 can be integrated with the processor 2301, or exist independently and be coupled to the processor 2301, and the embodiments of the present application do not make a limitation in this regard.

[0555] It should be noted that the structure of the communication device 2300 shown in FIG. 23 does not constitute a limitation on the communication device, and actually, the communication device can include more or fewer components than those shown, or combine certain components, or have different component arrangements.

[0556] In addition, the communication device 2300 can perform the information transmission method described above, and thus can obtain the technical effects described above, which will not be repeated here.

[0557] In a possible implementation, the embodiments of the present application further provide a computer-readable storage medium, which stores a computer program or instructions, and the computer program or instructions are executed by a computer to implement the functions of the above method embodiments.

[0558] In a possible implementation, the embodiments of the present application further provide a computer program product, which is executed by a computer to implement the functions of the above method embodiments.

[0559] In a possible implementation, the embodiments of the present application further provide a communication system, which includes the target RAN and the session management network element described in the above method embodiments, or the communication system includes the source RAN and the session management network element described in the above method embodiments, the communication system includes the access mobility management network element described in the above method embodiments, and the target RAN and / or the data management network element.

[0560] In a possible implementation, the embodiments of the present application further provide a communication method, which includes the method described in any of the above method embodiments or any implementation thereof.

[0561] In the above embodiments, all or part of the embodiments can be implemented by software, hardware, firmware or any combination thereof. When implemented by software, all or part of the embodiments can be implemented in the form of a computer program product. The 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 processes or functions according to the embodiments of the present application are generated. The computer can be a general purpose computer, a special purpose computer, a computer network, or other programmable apparatus. The computer instructions can be stored in a computer readable storage medium or transmitted from one computer readable storage medium to another computer readable storage medium, for example, the computer instructions can be transmitted from one website, computer, server or data center to another website, computer, server or data center through wired (such as coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (such as infrared, wireless, microwave, etc.) mode. The computer readable storage medium can be any available medium that can be accessed by a computer or data storage device such as one or more servers, data centers, etc. integrated with one or more media. The available media can be magnetic media (such as floppy disk, hard disk, magnetic tape), optical media or semiconductor media (such as solid state drive (SSD)) and the like.

[0562] Those skilled in the art can appreciate that the units and algorithm steps of the 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 the functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. A person 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 the present application.

[0563] Those skilled in the art can clearly understand that, for the convenience and brevity of the description, the specific working processes of the above-described system, device and unit can refer to the corresponding processes in the foregoing method embodiments, which will not be described here.

[0564] In several embodiments provided in the present application, it should be understood that the disclosed system, device and method can be implemented in other manners. For example, the described device embodiments are merely illustrative. For example, the division of the units is only a logical function division. There can be another division manner for the actual implementation, for example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the displayed or discussed mutual couplings or direct couplings or communication connections can be indirect couplings or communication connections through some interfaces, devices or units, and can be in electrical, mechanical or other forms.

[0565] The units described as separate components can or can not be physically separate, and the components shown as units can or can not be physical units, i.e., can be located in one place, or can be distributed on multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the embodiment.

[0566] In addition, each functional unit in the various embodiments of the present application can be integrated into a processing unit, or each unit can be a physically independent unit, or two or more units can be integrated into a unit.

[0567] If the functions are implemented in the form of software function units and sold or used as independent products, they can be stored in a computer readable storage medium. Based on this understanding, the technical solutions of the present application essentially or the part that contributes to the prior art or part of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium, and includes a number of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present application. The aforementioned storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, and various media that can store program codes.

[0568] Although the application has been described in connection with the embodiments thereof with reference to the various drawings, it will be understood that other variations and modifications of the details, and specific examples can be resorted to by those skilled in the art without departing from the scope of the application. It will be noted that the term "comprising" does not, by itself, exclude other components or steps, and the singular return to plural is not excluded unless otherwise indicated. A single processor or other unit can fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. The claims are not intended to be limited to the aspects of the application specifically recited in the description and / or claims.

[0569] Although the application has been described in connection with specific embodiments thereof, it will be understood that it is capable of modifications and alternative constructions and combinations of parts herein described, drawings and examples without departing from the scope of the application as set out in the claims. Accordingly, the above description and drawings are to be regarded as illustrative in nature and not restrictive.

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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