Network communication method, apparatus and medium

Abstract

The application provides an inter-network communication method, device and medium, relates to the technical field of communication, and is used for solving the problem that continuous inter-network communication is difficult to realize when a UE moves across networks in a connected state in the prior art. The method comprises the following steps: acquiring cross-network connected state signaling of a user equipment (UE) moving from a first public land mobile network (PLMN) to a second PLMN in a connected state, wherein the cross-network connected state signaling comprises real information or hidden information related to a connected state service context of the UE in the first PLMN; and processing the cross-network connected state signaling based on the real information or hidden information related to the connected state service context of the UE in the first PLMN, so as to realize connected state continuous communication of the UE between the first PLMN and the second PLMN. The application ensures that the communication service of the UE in the first PLMN can be continuously maintained in the second PLMN, thereby realizing inter-network continuous communication when the UE moves across networks in a connected state, guaranteeing user communication quality, and improving user experience.

Description

Technical Field

[0001] This invention relates to the field of communication technology, and in particular to an inter-network communication method, an inter-network communication device, an electronic device, and a computer-readable storage medium. Background Technology

[0002] Existing network communication technologies typically refer to international roaming. The typical use case for international roaming is as follows: a user turns off their phone while traveling, turns it on upon arrival in the roaming country or region, and then registers for international roaming on the local network. During the international roaming registration process, a service discovery process is initiated, and the user's subsequent communication process is started based on the service discovery results. Even if the user does not turn off their phone during the trip, they may lose their home network signal at some point in the journey. When they arrive at a place with international roaming signal, they will re-register for international roaming.

[0003] However, with the development of network technology, a new inter-network communication requirement scenario has emerged. When a UE moves in a connected state between two consecutive PLMNs (with some overlap in coverage areas), certain inter-network signaling interactions can be completed between the PLMNs before and after the move to transfer the user's communication service parameters from the network before the move to the network after the move. This ensures that the user's connected communication services are not interrupted during the move, thus achieving continuous inter-network communication. However, there is no existing technology for implementing this process. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to address the above-mentioned shortcomings of the prior art by providing an inter-network communication method, inter-network communication device, electronic device and computer-readable storage medium, so as to solve the problem that it is difficult to achieve continuous inter-network communication when the UE moves across networks in a connected state.

[0005] In a first aspect, the present invention provides an inter-network communication method, applied to a Public Land Mobile Network (PLMN) or its network elements, comprising:

[0006] Acquire cross-network connection state signaling of a user equipment (UE) that has moved from the first PLMN to the second PLMN in a connected state. The cross-network connection state signaling contains real or hidden information related to the connected state service context of the UE in the first PLMN.

[0007] Cross-network connection-state signaling is processed based on real or hidden information related to the connection-state service context of the UE in the first PLMN, so as to realize continuous connection-state communication between the UE in the first PLMN and the second PLMN.

[0008] In a second aspect, the present invention provides an inter-network communication device, comprising:

[0009] The acquisition module is used to acquire cross-network connection state signaling of a user equipment (UE) that has moved from the first PLMN to the second PLMN in a connected state. The cross-network connection state signaling contains real or hidden information related to the connection state service context of the UE in the first PLMN.

[0010] The processing module, connected to the acquisition module, is used to process cross-network connection-state signaling based on real or hidden information related to the connection-state service context of the UE in the first PLMN, so as to realize continuous connection-state communication between the UE in the first PLMN and the second PLMN.

[0011] Thirdly, the present invention provides an electronic device, comprising:

[0012] A memory that stores programs;

[0013] The processor, when running the program stored in the memory, performs the inter-network communication method as described above.

[0014] Fourthly, the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein when the computer program is executed by a processor, it implements the inter-network communication method as described above.

[0015] This invention provides an inter-network communication method, an inter-network communication device, an electronic device, and a computer-readable storage medium. When a UE moves from a first PLMN to a second PLMN in a connected state, it acquires cross-network connected state signaling containing information related to the UE's connected state service context in the first PLMN. By processing this cross-network connected state signaling, it ensures that the UE's communication services in the first PLMN continue in the second PLMN, thereby achieving continuous inter-network communication when the UE moves across networks in a connected state, ensuring user communication quality, and improving user experience. Attached Figure Description

[0016] Figure 1 It is a schematic diagram showing the location of a network element in a network;

[0017] Figure 2 This is a schematic diagram of the topology hiding and restoration process;

[0018] Figure 3 This is a schematic diagram illustrating the division of a network into network elements.

[0019] Figure 4 This is a flowchart of an inter-network communication method according to an embodiment of the present invention;

[0020] Figure 5 This is an interactive flowchart of the first method of inter-network communication in this embodiment of the invention;

[0021] Figure 6This is an interactive flowchart of the second inter-network communication method in this embodiment of the invention;

[0022] Figure 7 This is an interactive flowchart of the third method of inter-network communication in this embodiment of the invention;

[0023] Figure 8 This is an interactive flowchart of the fourth method of inter-network communication in this embodiment of the invention;

[0024] Figure 9 This is an interactive flowchart of method five for inter-network communication in this embodiment of the invention;

[0025] Figure 10 This is an interactive flowchart of method six for inter-network communication in this embodiment of the invention;

[0026] Figure 11 This is an interactive flowchart of the seventh inter-network communication method in this embodiment of the invention;

[0027] Figure 12 This is an interactive flowchart of the eighth inter-network communication method in this embodiment of the invention;

[0028] Figure 13 This is a schematic diagram of the structure of an inter-network communication device according to an embodiment of the present invention;

[0029] Figure 14 This is a schematic diagram of the structure of an electronic device according to an embodiment of the present invention. Detailed Implementation

[0030] To enable those skilled in the art to better understand the technical solution of the present invention, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0031] It is understood that the specific embodiments and accompanying drawings described herein are merely for explaining the invention and are not intended to limit the invention.

[0032] It is understood that, without conflict, the various embodiments and features in the embodiments of the present invention can be combined with each other.

[0033] It is understood that, for ease of description, only the parts related to the present invention are shown in the accompanying drawings, while the parts unrelated to the present invention are not shown in the drawings.

[0034] It is understood that each unit or module involved in the embodiments of the present invention may correspond to only one entity structure, or may be composed of multiple entity structures, or multiple units or modules may be integrated into one entity structure.

[0035] It is understood that, without conflict, the functions and steps marked in the flowcharts and block diagrams of this invention may occur in a different order than that marked in the accompanying drawings.

[0036] It is understood that the flowcharts and block diagrams of this invention illustrate the possible architecture, functions, and operations of systems, apparatuses, devices, and methods according to various embodiments of this invention. Each block in the flowchart or block diagram may represent a unit, module, program segment, or code, containing executable instructions for implementing the specified function. Furthermore, each block or combination of blocks in the block diagram and flowchart can be implemented using a hardware-based system to achieve the specified function, or using a combination of hardware and computer instructions.

[0037] It is understood that the units and modules involved in the embodiments of the present invention can be implemented by software or by hardware. For example, the units and modules can be located in a processor.

[0038] To facilitate understanding of this invention, the following will be combined with... Figure 1-3 This invention introduces some of the network structures involved in the present invention.

[0039] Section 5.9.3.3 of 3GPP (3rd Generation Partnership Project) TS33.501 (R15 TS 33.501 5G System Security Architecture and Processes) requires that: The SEPP shall perform topology hiding by limiting the internal topology information visible to external parties. That is, in the 5G (5th Generation Mobile Communication Technology) SA (Standalone) network sharing and international roaming architecture, the SEPP (Security Edge Protection Proxy) should perform topology hiding by restricting the internal topology information visible to external parties.

[0040] In a PLMN (Public Land Mobile Network), the locations of each network element are as follows: Figure 1As shown, vSEPP (Visited SEPP, Visited PLMN) and hSEPP (Home SEPP, Home SEPP) are set up between the two networks (VPLMN (Visited PLMN) and HPLMN (Home PLMN)). These networks hide and restore the network topology information contained in the signaling sent from the local network to the other network, respectively, in order to meet the requirements of 3GPP and ensure the information security of the local network. In addition to SEPP, each network element also includes AMF (Access and Mobility Management Function) and SMF (Session Management Function). HPLMN can be configured with I-SMF (Inter-SMF). When the home operator network has I-SMF, the home network's anchor SMF (SMF that handles cross-network signaling) is written as A-SMF (Anchor SMF). Otherwise, it can be directly called H-SMF (Home SMF). The corresponding network element of VPLMN is called V-SMF (Visit SMF). UE (User Equipment) connects to the corresponding PLMN in the base station coverage area of ​​RAN (Radio Access Network). The communication interfaces between network elements are generally named in the form of N + numbers, with different numbers representing different communication connections between network elements.

[0041] like Figure 2 and Figure 3 As shown, it can be Figure 1 The network elements serving within each core network are categorized as NF (Network Functions) network elements. SEPP provides inter-network services, including hiding and restoring the local network topology information in cross-network signaling. A simplified illustration of this process is shown below. Figure 2As shown, during NF communication between PLMNs, to prevent the peer PLMN (i.e., other PLMNs) from obtaining the local PLMN's topology information based on FQDN (Fully Qualified Domain Name) information or other important network information (such as IP (Internet Protocol) addresses), SEPP needs to topology-hide the FQDN or other important network information of the local NF in all messages sent to other PLMNs. All FQDN information or other important network information of the local PLMN NF, when passing through SEPP, will be replaced with the topology-hidden FQDN based on SEPP's local configuration, preventing the peer PLMN from obtaining the local PLMN's topology information based on the FQDN or other important network information; simultaneously, when the message returns, the hidden FQDN needs to be replaced back with the original FQDN or other important network information. Generally, the local network and other networks might be like this... Figure 3 The vPLMN and hPLMN are shown, but the possibility of the UE moving between the two vPLMNs cannot be ruled out.

[0042] Current standards and technologies do not clearly define specific implementation schemes for SEPP topology hiding. Generally, each equipment manufacturer independently designs its own topology hiding implementation scheme for its SEPP. Currently, there are no standards or definitions regarding which information SEPP needs to topology hide when a UE moves across networks in connected mode. Without topology hiding of signaling for inter-network communication, two consequences arise: leakage of sensitive information from the local network to other networks and interference from local network IP addresses with signaling processing on other networks. This impacts information security and can lead to service failures. Currently, SEPP's topology hiding mainly hides the FQDN in the NRF (NF Register Function) network element discovery response between PLMNs of the home network. For example, when a UE initiates registration in a VPLMN, the NF of the visited network needs to discover the NF in the HPLMN through vSEPP and hSEPP. This usually includes UDM (Unified Data Management) discovery, AUSF (Authentication Server Function) discovery, and hSMF discovery. The NRF of the home network needs to return the FQDN of the above networks to hSEPP in the response. After topology hiding, hSEPP forwards it to vSEPP and vNF.

[0043] The scenarios addressed in this application include, for example, 5G network sharing among multiple operators in my country, international roaming with land borders, and roaming between mainland my country and Hong Kong, Macao and Taiwan. In these scenarios, users may move from the coverage area of ​​a first PLMN to the coverage area of ​​a second PLMN by land transportation. During the movement, the user UE maintains a call or other network services. In order to ensure the continuity of services, this application does not want to redo service discovery when switching networks, because the new network element discovered by the service will usually interrupt the previous services to some extent.

[0044] However, there is currently no solution to hide the topology of signaling processes other than service discovery, nor is there a solution to hide the parameters in the signaling message body. When a UE moves between two networks in a connected state, in order to ensure that user services are not interrupted, it is necessary to exchange certain context information of prior services between the two networks. For example, it is necessary to hide the network element address obtained from the prior service context (such as the prior PDU (Protocol Data Unit, PDU) session context). Therefore, for this scenario, it is necessary to design cross-network connected state signaling that ensures that UE services are not interrupted, and it is necessary to agree on a topology hiding scheme for cross-network connected state signaling on SEPP. These cross-network connection-state signaling may include: 1) When a connected UE moves between the visited network and the home network, the new AMF (the AMF of the network after the move) obtains the UEContext from the old AMF (the AMF of the network before the move) through the N14 interface across the PLMN, where the UEContext contains sensitive information from the old PLMN; 2) When a connected UE moves between the visited network and the home network, if the home network has an I-SMF, the V-SMF and I-SMF read the SMContext through the N38 interface across the PLMN, where the SMContext contains sensitive information from the old PLMN; 3) When a connected UE moves between the visited network and the home network, if the home network does not have an I-SMF, the V-SMF and H-SMF read the SMContext through the N16 interface across the PLMN, where the SMContext contains sensitive information from the old PLMN. Sensitive information in PLMN; the problems with the above signaling methods are that, on the one hand, they can lead to the leakage of local network topology information or other sensitive information to other networks; on the other hand, if the sensitive information is an IP address, since PLMNs cannot communicate directly via IP addresses, subsequent service requests will fail.Note: In existing technology, the N14 interface refers to the interface between AMFs within the same network. That is, if the new AMF and the old AMF belong to the same operator network, such as both belonging to the home operator or both belonging to the visited operator, service continuity can be guaranteed when the UE moves between operators. However, when the UE moves between the home operator network and the visited operator network, the new AMF and the old AMF... AMFs belong to different operators. To ensure the continuity of UE services, i.e., no dropped voice calls and no interruption of data services, especially real-time data services, an N14-like interface needs to be designed. The N14-like interface is a cross-PLMN interface, that is, the AMF connects to the local network SEPP through this interface, and the local network SEPP and the cross-network SEPP indirectly connect to the cross-network AMF. Similarly, in the prior art, the interface between vSMFs and hSMFs is called the N16 interface, the interface between I-SMF and A-SMF is called the N16a interface, and the interface between vSMF and I-SMF is called the N38 interface. The cross-PLMN N** interface is the N**-like interface designed in this application. These interfaces are used to agree that the SEPP will forward the corresponding cross-network connection state signaling across networks, and at the same time, perform topology hiding and restoration in the SEPP. These interfaces may be given other names in the future. In this application, they are still named N14, N16, etc., because the signaling they send and receive is similar to these existing interfaces. The change in naming does not change the nature of the interface. Due to security requirements, operators cannot communicate with each other via IP addresses. Therefore, the format after topology hiding is FQDN. The SEPP of the message receiver maps the FQDN to the local network's IP address and then routes it to the local network's NF. In addition, IP addresses between different operators are planned separately, and the address space may overlap. Even without security considerations, networks cannot communicate directly using IP addresses.

[0045] SEPPs located in two networks communicating with each other can be distinguished as pSEPP (producer SEPP) and cSEPP (consumer SEPP). The signaling for topology hiding in inter-network communication includes: 1) When pSEPP returns an NRF service discovery response, it hides the FQDN or IP address of the NF. When a subsequent service request is received, the FQDN or IP address is restored; 2) When cSEPP sends a service request to the inter-network, it hides the FQDN information in the callback URI (Uniform Resource Identifier). The backend restores the FQDN in subsequent notification messages; 3) When pSEPP sends a service response to the inter-network, it hides the FQDN information in the Location header field (representing the location information of the NF that issued the response, generally the FQDN of the NF and the specific location of the service in the NF, usually a string of numbers separated by slashes after the FQDN, generated by the NF). When a subsequent service request is received, the FQDN is restored. Specific topology hiding methods include: when SEPP sends service messages to the inter-network, deleting relevant information of other NFs in the Via (General) header field and retaining only SEPP information; when SEPP sends service messages to the inter-network, deleting specified HTTP header fields that do not affect the service; encrypting specified information related to the topology in the FQDN to generate the hidden FQDN; and encrypting the IP address information to generate the hidden FQDN format. Topology hiding can be further divided into the following types depending on the network element settings: 1) When cSEPP sends a service request to the inter-network, it replaces the IP address in smcontextRef with the topology-hidden FQDN, which points to I-SMF, V-SMF, or SMF; or when cSEPP sends a service request to the inter-network, it replaces the FQDN in smcontextRef with the topology-hidden FQDN, which points to V-SMF; 2) When pSEPP sends a service response to the inter-network, it replaces the IP address in smcontextRef with the topology-hidden FQDN, which points to I-SMF, V-SMF, or SMF; or when pSEPP sends a service response to the inter-network, it replaces the FQDN address in smcontextRef with the topology-hidden FQDN, which points to V-SMF. Topology restoration can be performed by the SEPP that implements topology hiding or the SEPP that provides disaster recovery or load sharing when it receives subsequent service requests. The design of the SEPP for disaster recovery and load sharing is a separate inventive concept, but the disaster recovery and load sharing design of the SEPP can be introduced in the scenario of this application.

[0046] The above is a brief introduction to the present invention. The content claimed in this application will be described in detail below with reference to specific embodiments.

[0047] Example 1:

[0048] like Figure 4 As shown, Embodiment 1 of the present invention provides an inter-network communication method, applied to a Public Land Mobile Network (PLMN) or its network elements, comprising:

[0049] S1. Obtain cross-network connection state signaling of a user equipment UE that has moved from the first PLMN to the second PLMN in a connected state. The cross-network connection state signaling contains real or hidden information related to the connection state service context of the UE in the first PLMN.

[0050] S2. Process cross-network connection-state signaling based on the real or hidden information contained in the connection-state service context of the UE in the first PLMN, so as to realize continuous connection-state communication between the UE in the first PLMN and the second PLMN.

[0051] Specifically, in this embodiment, an inter-network communication method can refer to a processing flow of cross-network connection-state signaling by the PLMN as a whole at its own end, a processing flow of cross-network connection-state signaling by a certain network element of the PLMN, or a processing flow of cross-network connection-state signaling by cooperation among several local network elements of the PLMN. The PLMN can be the first PLMN before the move or the second PLMN after the move. The network elements of the PLMN can be NF network elements or SEPP network elements. Regardless of the executing entity, the process is to obtain cross-network connection-state signaling containing information related to the connection-state service context of the UE in the first PLMN when the UE moves from the first PLMN to the second PLMN in a connected state. By processing the cross-network connection-state signaling, the communication service of the UE in the first PLMN is ensured to continue in the second PLMN, thereby realizing continuous inter-network communication when the UE moves across networks in a connected state, ensuring user communication quality, and improving user experience. Information related to the UE's connected-state service context in the first PLMN can be either real information directly taken from the UE's connected-state service context in the first PLMN, or hidden information obtained by hiding the real information directly taken from the UE's connected-state service context in the first PLMN. The specific content of this information should be limited to ensuring service continuity.

[0052] Optionally, the real or hidden information related to the UE's connection-state service context in the first PLMN specifically includes:

[0053] The first PLMN real topology information of the UE in the first PLMN connected-state service context, or the first PLMN hidden topology information obtained by topology hiding the first PLMN real topology information of the UE in the first PLMN connected-state service context, and / or the UE in the first PLMN connected-state service context.

[0054] Specifically, in this embodiment, the information carried in the cross-network connection-state signaling for achieving continuous connection-state communication can be: the UE's actual topology information of the first PLMN in the connection-state service context of the first PLMN, such as the network element address of the first PLMN that provides services to the UE in the original service. By carrying this address, subsequent signaling is sent to that network element for processing, so that the UE continues to maintain the original connection-state service. For example, in a 5G network, continuity needs to be achieved between the local 5G coverage and the 5G coverage of other networks, that is, to ensure that the user's calls are not interrupted and the Internet service is not delayed. This involves the connection-state handover or connection-state redirection process. In this process, the UE context and PDU session context are obtained. The topology information carried in this process parameter is not available in the prior art. In the session continuity scenario, such as when the UE moves to the visited network, the H-SMF information is obtained through the session context. There is no existing international topology information for H-SMF. The initial roaming discovery process involves: topology hiding of the UE's actual topology information within the first PLMN's connected-mode service context to obtain the hidden topology information of the first PLMN. From the perspective of a single network element, as mentioned earlier, the network element address that the first PLMN provides services to the UE in the original service is the actual address at the local end and the hidden address at the peer end (hidden by the local end and sent to the peer end). However, both will point to the same network element, thus maintaining the original connected-mode service. Within the first PLMN's connected-mode service context, the first PLMN can send the UE's original connected-mode service context to the second PLMN. The second PLMN can then continue to provide subsequent connected-mode service services to the UE based on the original connected-mode service context. The UE can send the hidden topology information after providing the network element address that the first PLMN provides services to the UE in the original service to the second PLMN within the first PLMN's connected-mode service context.

[0055] Optionally, cross-network connection-state signaling is processed based on real or hidden information related to the connection-state service context of the UE in the first PLMN, to achieve continuous connection-state communication between the UE and the second PLMN, specifically including:

[0056] If the cross-network connection state signaling is the first cross-network connection state signaling, and the first cross-network connection state signaling contains the first PLMN real topology information of the UE in the connection state service context of the first PLMN, then topology hiding is performed on the first PLMN real topology information in the first cross-network connection state signaling to obtain the second cross-network connection state signaling containing the first PLMN hidden topology information, so that the second PLMN responds to the second cross-network connection state signaling.

[0057] Specifically, in this embodiment, according to 3GPP requirements, before sending a message from the local SEPP to the peer SEPP, the local SEPP should convert, modify, or replace the FQDN information or other important network information, such as number ranges and IP addresses, in the signaling through topology hiding to avoid exposure to other operators. Therefore, provided that the first PLMN complies with 3GPP requirements, the first cross-network connection state signaling containing the true topology information of the first PLMN in the connection state service context of the UE in the first PLMN will be submitted by the NF network element of the first PLMN to the SEPP network element of the first PLMN for topology hiding, and then sent to the second PLMN. There are also cases where the first PLMN does not meet 3GPP requirements. This could be because the first PLMN itself does not comply with 3GPP requirements, or because the first PLMN has not been upgraded for the scenario proposed in this application. That is, the first PLMN's processing of other signaling procedures complies with 3GPP requirements, but its processing of the first cross-network connection state signaling described in this application does not. In this case, an alternative scheme can be added to the second PLMN to detect whether the signaling sent from the other network contains the real topology information of the other network. If it does, the second PLMN initiates topology hiding of the real topology information of the other network, thereby enabling the second PLMN to correctly respond to the first cross-network connection state signaling even if the first PLMN does not perform topology hiding processing. It is understood that when the same PLMN is used for different UEs to move, if the UE moves from the local network to the other network, the local network is the first PLMN; if the UE moves from the other network to the local network, the local network is the second PLMN. Therefore, the above two processing schemes can be set in the same network. In addition, the word "response" has at least two uses in this application: as a verb and as a signaling name. When used as a verb, the action of responding does not necessarily generate response-type signaling. It may generate response-type signaling, other types of signaling, or no signaling.

[0058] Optionally, the first cross-network connection state signaling is generated for the UE by the first network function (NF) element of the first PLMN, the connection state service context of the UE in the first PLMN is the protocol data unit (PDU) session context of the UE in the first PLMN, and the real topology information of the first PLMN is the real address of the second NF element of the first PLMN responsible for processing the PDU session of the first PLMN for the UE.

[0059] Specifically, in this embodiment, regardless of whether the first PLMN or the second PLMN performs topology hiding on the first cross-network connection state signaling, the first cross-network connection state signaling is generated for the UE by the first NF network element of the first PLMN. Specifically, it obtains the real address of the second NF network element of the first PLMN from the UE's PDU session context in the first PLMN, and generates the first cross-network connection state signaling carrying this real address. This allows subsequent signaling to be sent to the second NF network element of the first PLMN based on this real address to continue the UE's PDU session in the first PLMN. The first NF network element and the second NF network element refer to the source network element and the target network element in the first PLMN during a round-trip signaling process. These two can be the same network element or different network elements.

[0060] Optional:

[0061] The format of the real address of the second NF network element of the first PLMN is Internet Protocol IP address or Fully Qualified Domain Name (FQDN);

[0062] The hidden topology information of the first PLMN is specifically the hidden address of the second NF network element of the first PLMN in FQDN format, which corresponds to the real address of the second NF network element of the first PLMN.

[0063] Specifically, in this embodiment, since IP addresses are planned and allocated separately between different networks, there is an overlap between IP address spaces and IP routes. Therefore, IP address routing cannot be used for addressing. In order to ensure that the message parameter format containing FQDN does not change, SEPP maintains the FQDN format after performing topology hiding on the FQDN. The advantage of doing so is that it can be compatible with the network element's check of message format. Other important network information also becomes FQDN format after topology hiding. That is, the FQDN before topology hiding is the real address of the second NF network element of the first PLMN, which can also be in IP address format. The FQDN after topology hiding is the hidden address of the second NF network element of the first PLMN.

[0064] Optionally, the method is applied to the first NF network element of the first PLMN;

[0065] Topology hiding is performed on the first PLMN's true topology information in the first cross-network connection state signaling to obtain a second cross-network connection state signaling containing the first PLMN's hidden topology information, so that the second PLMN responds to the second cross-network connection state signaling, specifically including:

[0066] The first cross-network connection state signaling is sent to the Security Edge Protection Agent (SEPP) network element of this network, so that the SEPP network element of this network performs topology hiding of the real address of the second NF network element of this network in the first cross-network connection state signaling, so as to obtain the second cross-network connection state signaling containing the hidden address of the second NF network element of this network, and sends the second cross-network connection state signaling to the second PLMN, so that the second PLMN responds to the second cross-network connection state signaling.

[0067] Specifically, in this embodiment, the 3GPP requirement implicitly includes two technical points: signaling between different network elements (NFs) must be forwarded through the SEPP; signaling between NFs in different networks can only be routed via FQDN addressing, not via IP address addressing, and the two networks only expose each other's SEPP outward IP addresses. When the first PLMN processes the first cross-network connection state signaling generated by its own network in accordance with the 3GPP requirement, topology hiding is performed by the local network SEPP, resulting in an interactive process between the first NF network element and the local network SEPP network element for processing the first cross-network connection state signaling.

[0068] Optionally, the first cross-network connection state signaling is sent to the local network security edge protection agent (SEPP) network element, specifically including:

[0069] The first cross-network connection state signaling is sent to the SEPP network element of this network through the first cross-network connection state signaling communication interface of this network. The first cross-network connection state signaling communication interface of this network is a pre-established interface through which the first NF network element of this network transfers the signaling to be sent to the NF network element of another network to the SEPP network element of this network.

[0070] Specifically, in this embodiment, the first cross-network connection state signaling communication interface of this network refers to the previously introduced N14 interface, N16 interface, N38 interface, etc.

[0071] Optionally, the first NF network element of this network is specifically the Mobility and Access Management Function (AMF) network element of this network, and the second NF network element of this network is specifically the Session Management Function (SMF) network element of this network. The method specifically includes:

[0072] If the AMF network element of this network receives a radio configuration handover request sent by the base station of this network for a UE that has moved from this network to another network in a connected state, then generates a first Create UE Context Request signaling to be sent to the second PLMN according to the radio configuration handover request. The first Create UE Context Request signaling contains the real address of the SMF network element of this network in the PDU session context of this network.

[0073] The local AMF network element sends the first Create UE Context Request signaling to the local SEPP network element, so that the local SEPP network element performs topology hiding of the real address of the local SMF network element in the first Create UE Context Request signaling, thereby obtaining a second Create UE Context Request signaling containing the hidden address of the local SMF network element, and sends the second Create UE Context Request signaling to the second PLMN, so that the second PLMN responds to the second Create UE Context Request signaling.

[0074] Optionally, the first NF network element of this network is specifically an intermediate hI-SMF network element belonging to the hPLMN, and the second NF network element of this network is specifically an anchor point hA-SMF network element of the hPLMN; or, the first NF network element of this network is specifically an h-SMF network element of the hPLMN, and the second NF network element of this network is specifically an h-SMF network element of the hPLMN. The method specifically includes:

[0075] If the UE moves from the hPLMN to the visited vPLMN in a connected state, and the hI-SMF network element / h-SMF network element receives a PDU session context request signaling sent by the vPLMN to the UE based on the second Create UE Context Request signaling from the hPLMN, then the hI-SMF network element / h-SMF network element generates a first type A PDU session context response signaling to be sent to the vPLMN based on the PDU session context request signaling. The first type A PDU session context response signaling contains the real address of the hA-SMF network element / h-SMF network element in the UE's PDU session context in this network.

[0076] The hI-SMF network element / h-SMF network element sends the first Type A PDU session context response signaling to the local SEPP network element, so that the local SEPP network element performs topology hiding on the real address of the hI-SMF network element / h-SMF network element in the first Type A PDU session context response signaling to obtain the second Type A PDU session context response signaling containing the hidden address of the hI-SMF network element / h-SMF network element, and sends the second Type A PDU session context response signaling to the vPLMN, so that the vPLMN responds to the second Type A PDU session context response signaling.

[0077] Optionally, the first NF network element of this network is specifically the Mobility and Access Management Function (AMF) network element of this network, and the second NF network element of this network is specifically the Session Management Function (SMF) network element of this network. The method specifically includes:

[0078] If the local AMF network element receives a UE context creation request sent by the second PLMN for the UE, it generates a first UE context creation response signaling to be sent to the second PLMN according to the UE UE creation UE context request. The first UE context creation response signaling contains the real address of the local SMF network element in the local PDU session context of the UE.

[0079] The local AMF network element sends the first Create UE Context Response signaling to the local SEPP network element, so that the local SEPP network element performs topology hiding on the real address of the local SMF network element in the first Create UE Context Response signaling, thereby obtaining the second Create UE Context Response signaling containing the hidden address of the local SMF network element, and sends the second Create UE Context Response signaling to the second PLMN, so that the second PLMN responds to the second Create UE Context Response signaling.

[0080] Optionally, the first NF network element of this network is specifically an intermediate hI-SMF network element belonging to the hPLMN, and the second NF network element of this network is specifically an anchor point hA-SMF network element of the hPLMN; or, the first NF network element of this network is specifically an h-SMF network element of the hPLMN, and the second NF network element of this network is specifically an h-SMF network element of the hPLMN. The method further includes:

[0081] If the UE moves from the hPLMN to the visited vPLMN in a connected state, and the hI-SMF network element / h-SMF network element receives a PDU session context request signaling sent by the vPLMN to the UE based on the second Create UE Context Response signaling from the hPLMN, then the hI-SMF network element / h-SMF network element generates a first type A PDU session context response signaling to be sent to the vPLMN based on the PDU session context request signaling. The first type A PDU session context response signaling contains the real address of the hA-SMF network element / h-SMF network element in the UE's PDU session context in this network.

[0082] The hI-SMF network element / h-SMF network element sends the first Type A PDU session context response signaling to the local SEPP network element, so that the local SEPP network element performs topology hiding on the real address of the hI-SMF network element / h-SMF network element in the first Type A PDU session context response signaling to obtain the second Type A PDU session context response signaling containing the hidden address of the hI-SMF network element / h-SMF network element, and sends the second Type A PDU session context response signaling to the vPLMN, so that the vPLMN responds to the second Type A PDU session context response signaling.

[0083] Specifically, in this embodiment, prior communication services can be resumed by sending UE context and PDU session context between two networks. For signaling sent based on the UE context, the UEContext is obtained through the N14-class interface between AMFs. The inclusion relationship of this parameter is: UEContext->SessionContext->pdusessionContext->smcontextRef. Topology hiding is performed on the smcontextRef in the UEContext parameter. Subsequently, the topology hiding of smcontextRef is restored through the N16-class interface between V-SMF and H-SMF to enable subsequent signaling to be sent based on the PDU session context. This can include four mobility scenarios:

[0084] 1) When a connected UE moves from its home network to a visited network, resulting in an N2 handover (radio configuration handover) across PLMNs, the home network's AMF (old AMF, consumer AMF) sends a Namf_Communication_CreateUEContext request message to the visited network's AMF (new AMF, producer AMF). This message carries an smcontextRef. If the PDU session in the home network does not have an I-SMF, the smcontextRef contains the IP address of the home network's anchor SMF. If the PDU session in the home network has an I-SMF, the smcontextRef contains the IP address of the home network's I-SMF. If the home network's SEPP does not hide the IP address in the smcontextRef, the home network's IP address information will be leaked to the visited network. Furthermore, the home and visited networks cannot communicate directly using IP addresses, causing subsequent signaling processes during the handover to fail, thus causing the entire handover process to fail. Therefore, the home network's SEPP (consumer SEPP) needs to modify the CreateUEContext. The IP address information in the smcontextRef of the request message is encrypted and replaced with the topology-hidden FQDN. This topology-hidden FQDN points to the home network's I-SMF or A-SMF. After topology hiding by H-SEPP, in subsequent processes, the smcontextRef carried in the Nsmf_PDUSession_CreateSMContext Request message sent by vAMF to vSMF does not contain the IP address, but rather the topology-hidden FQDN. The Nsmf_PDUSession_Context Request message sent by v-SMF to the home network's I-SMF (A-SMF) also does not contain the IP address, but rather the topology-hidden FQDN. Based on this FQDN, vAMF forwards the message to vSEPP, vSEPP forwards it to h-SEPP, and when hSEPP forwards the above message to the NF of its own network, it needs to restore the topology-hidden FQDN contained in smcontextRef to the IP address information so that it can be routed normally within the home network.

[0085] 2) When a connected UE moves from the visited network to the home network, a cross-PLMN N2 handover occurs. The visited network's AMF (old AMF, consumer AMF) sends a Namf_Communication_CreateUEContext request message to the home network's AMF (new AMF, producer AMF). This message carries an smcontextRef, which contains the IP address or FQDN of the visited network's V-SMF. If the visited network's SEPP does not hide the IP address or FQDN in the smcontextRef, the visited network's IP address or topology information will be leaked to the home network. Furthermore, the home and visited networks cannot communicate directly using IP addresses, potentially causing subsequent signaling processes during the handover to fail, thus causing the entire handover process to fail. Therefore, the visited network's SEPP (consumer SEPP) needs to create the UEContext. The IP address or the original FQDN containing topology information in the smcontextRef of the request message is replaced with the topology-hidden FQDN. This topology-hidden FQDN points to the V-SMF of the visited network. After topology hiding by v-SEPP, in subsequent processes, the Nsmf_PDUSession_CreateSMContext Request message sent by hAMF to I-SMF (or A-SMF) carries the topology-hidden FQDN of v-SMF in smcontextRef. The Nsmf_PDUSession_Context Request message sent by hAMF to the v-SMF of the visited network carries the topology-hidden FQDN in smcontextRef. Based on this FQDN, hAMF forwards the message to hSEPP, hSEPP forwards it to v-SEPP. When vSEPP forwards the above message to the NF of its own network, it needs to restore the topology-hidden FQDN contained in smcontextRef to IP address information so that it can be routed normally within the visited network.

[0086] 3) When a UE moves from its home network to a visited network, a mobility registration update occurs. The visited network's AMF (new AMF, producer AMF) sends a Namf_Communication_UEContextTransfer Request to the home network's AMF (old AMF, consumer AMF). The home network's AMF (old AMF, consumer AMF) sends a Namf_Communication_UEContextTransfer Request to the visited network's AMF (new AMF, producer AMF). The AMF sends a response message Namf_Communication_UEContextTransferResponse, which carries smcontextRef. When the PDU session in the home network does not have an I-SMF, smcontextRef contains the IP address of the home network's anchor SMF. When the PDU session in the home network has an I-SMF, smcontextRef contains the IP address of the home network's I-SMF. If the SEPP (Producer Provider Interface) of the home network does not hide the IP address in smcontextRef, the home network's IP address information will be leaked to the visited network. Furthermore, the home network and the visited network cannot communicate directly using IP addresses, causing subsequent signaling processes during the handover to fail, thus causing the entire handover process to fail. Therefore, the home network's SEPP (Producer Provider Interface) needs to hide the IP address in smcontextRef. H-SEPP replaces the IP address in the smcontextRef of the UEContextTransferResponse response message with the topology-hidden FQDN. This topology-hidden FQDN points to the home network's I-SMF or A-SMF. After topology hiding by H-SEPP, in subsequent processes, the smcontextRef carried in the Nsmf_PDUSession_CreateSMContext Request message sent by vAMF to vSMF does not contain the IP address, but rather the topology-hidden FQDN. The Nsmf_PDUSession_Context Request message sent by vAMF to the home network's I-SMF (or A-SMF) also does not contain the IP address, but rather the topology-hidden FQDN. Based on this FQDN, vAMF forwards the message to vSEPP, vSEPP forwards it to h-SEPP, and when hSEPP forwards the above message to the NF of its own network, it needs to restore the topology-hidden FQDN contained in smcontextRef to the IP address information so that it can be routed normally within the home network.

[0087] 4) When a UE moves from the visited network to the home network, a mobility registration update occurs. The home network's AMF (new AMF, producer AMF) sends a Namf_Communication_UEContextTransfer Request to the visited network's AMF (old AMF, consumer AMF). The visited network's AMF (old AMF, consumer AMF) then sends a response message Namf_Communication_UEContextTransferResponse to the home network's AMF (new AMF, producer AMF). This response message carries an smcontextRef, which contains the IP address of the visited network's V-SMF or the original FQDN containing topology information. If the visited network's SEPP does not hide the IP address or topology information in the smcontextRef, the visited network's IP address or topology information will be leaked to the home network. Furthermore, the home network and the visited network cannot communicate directly using IP addresses, which may cause subsequent signaling processes during the handover procedure to fail, thus causing the entire handover procedure to fail. Therefore, the SEPP (producer SEPP) of the visited network needs to replace the IP address information or the original FQDN containing topology information in the smcontextRef of the UEContextTransfer Response message with a topology-hidden FQDN. This topology-hidden FQDN points to the V-SMF of the visited network. After topology hiding by the V-SEPP, in subsequent processes, the smcontextRef carried in the Nsmf_PDUSession_CreateSMContext Request message sent by the hAMF to the I-SMF (or anchor SMF) contains the topology-hidden FQDN. The Nsmf_PDUSession_Context message sent by the hAMF to the V-SMF of the visited network... The Request message carries an smcontextRef containing the topology-hidden FQDN. Based on this FQDN, hAMF forwards the message to hSEPP, hSEPP forwards it to v-SEPP, and when vSEPP forwards the above message to the NF of its own network, it needs to restore the topology-hidden FQDN contained in smcontextRef to the IP address information so that it can be routed normally within the visited network.

[0088] In all four scenarios above, there are alternative solutions as follows: The old AMF sends the smContextRef to the new AMF unchanged. The new AMF first determines whether it is a cross-carrier with the old AMF. If it is, it rediscovers the hSMF through cross-PLMN service discovery. The URL composed of IP and port number in smContextRef is replaced with the FQDN carried in the service discovery result (because these topology information generally carry IP addresses instead of FQDNs. Without topology hiding, not only will topology information be leaked, but communication will also be impossible). This solution can at least solve the problem of process failure between different PLMNs caused by smContextRef being an IP address and port. It cannot completely solve the problem of the old network element's IP address information being exposed to the new network, but it still has its significance. Moreover, this service discovery process is triggered by the new network based on the signaling sent by the old network, which is significantly different from the existing service discovery process.

[0089] Optionally, the method is applied to the local security edge protection agent (SEPP) network element of the first PLMN;

[0090] Topology hiding is performed on the first PLMN's true topology information in the first cross-network connection state signaling to obtain a second cross-network connection state signaling containing the first PLMN's hidden topology information, so that the second PLMN responds to the second cross-network connection state signaling, specifically including:

[0091] The real address of the second NF network element in this network is topologically hidden in the first cross-network connection state signaling from the first NF network element in this network, so as to obtain the second cross-network connection state signaling containing the hidden address of the second NF network element in this network, and the second cross-network connection state signaling is sent to the second PLMN so that the second PLMN responds to the second cross-network connection state signaling.

[0092] Optionally, the first cross-network connection state signaling is received from the first NF network element of this network through the first cross-network connection state signaling communication interface of this network. The first cross-network connection state signaling communication interface of this network is a pre-established interface through which the first NF network element of this network transfers the signaling to be sent to the NF network element of another network to the SEPP network element of this network.

[0093] Optional:

[0094] The first NF network element in this network is specifically the Mobility and Access Management Function (AMF) network element; the second NF network element in this network is specifically the Session Management Function (SMF) network element; and the first cross-network connection state signaling is specifically the first UE context creation request signaling or the first UE context creation response signaling; or...

[0095] The first NF network element of this network is specifically the intermediate hI-SMF network element belonging to the hPLMN, and the second NF network element of this network is specifically the anchor hA-SMF network element of the hPLMN. Alternatively, the first NF network element of this network is specifically the h-SMF network element of the hPLMN, and the second NF network element of this network is specifically the h-SMF network element of the hPLMN. The first cross-network connection state signaling is specifically the first Class A PDU session context response signaling.

[0096] Optionally, topology hiding is performed on the real address of the second NF network element in the first cross-network connection state signaling from the first NF network element of this network to obtain the second cross-network connection state signaling containing the hidden address of the second NF network element of this network, specifically including:

[0097] For the first cross-network connection state signaling from the first NF network element of this network, extract the real address of the second NF network element of this network in the format of Internet Protocol IP address or Fully Qualified Domain Name (FQDN);

[0098] The real address of the second NF network element in this network is topologically hidden based on the symmetric encryption algorithm, and the encryption result is converted into the hidden address of the second NF network element in this network in the format of FQDN.

[0099] Replace the real address of the second NF network element in the first cross-network connection state signaling with the hidden address of the second NF network element in this network to obtain the second cross-network connection state signaling.

[0100] Specifically, in this embodiment, the method executed by the local SEPP network element of the first PLMN corresponds to the method executed by the local NF network element. Please refer to the foregoing description of the method executed by the first NF network element. The specific topology hiding method can adopt a symmetric encryption algorithm, which will not be discussed in this application.

[0101] Optionally, the method is applied to the first NF network element of the second PLMN;

[0102] Topology hiding is performed on the first PLMN's true topology information in the first cross-network connection state signaling to obtain a second cross-network connection state signaling containing the first PLMN's hidden topology information, so that the second PLMN responds to the second cross-network connection state signaling, specifically including:

[0103] According to the first cross-network connection state signaling request, the Security Edge Protection Agent (SEPP) network element of this network initiates a service discovery request to the first PLMN, so that the SEPP network element of this network receives the service discovery response sent by the first PLMN according to the service discovery request;

[0104] The system receives the first PLMN hidden topology information in the service discovery response sent by the SEPP network element of this network, and replaces the first PLMN real topology information in the first cross-network connection state signaling with the first PLMN hidden topology information to obtain the second cross-network connection state signaling, and responds to the second cross-network connection state signaling in this network.

[0105] Optionally, based on the first cross-network connection state signaling request, the local network security edge protection agent (SEPP) network element initiates a service discovery request to the first PLMN, specifically including:

[0106] Determine whether the first cross-network connection state signaling comes from a different network. If so, determine whether the first cross-network connection state signaling contains the real address of the NF network element of the different network in the Internet Protocol IP format. If so, request the SEPP network element of this network to initiate a service discovery request to the first PLMN from which the first cross-network connection state signaling comes.

[0107] Specifically, in this embodiment, the method executed by the first NF network element of the second PLMN is an alternative to the method executed by the first NF network element of the first PLMN. It is used to remedy the topology hiding when the first PLMN does not perform topology hiding, so that the service process can continue. The concept of the first NF network element of the second PLMN is used here because the above process is usually triggered by the arrival of the first cross-network connection state signaling at the first NF network element of the second PLMN. This network element usually corresponds to the first NF network element of the first PLMN, such as old AMF (hAMF / vMF) and new AMF (vMF / hAMF).

[0108] Optionally, the method is applied to the local network elements of the second PLMN;

[0109] Cross-network connection-state signaling is processed based on real or hidden information related to the UE's connection-state service context in the first PLMN, to achieve continuous connection-state communication between the UE and the second PLMN, specifically including:

[0110] If the cross-network connection state signaling is the second cross-network connection state signaling, and the second cross-network connection state signaling contains the first PLMN hidden topology information obtained by topology hiding the first PLMN real topology information in the connection state service context of the UE in the first PLMN, then the third cross-network connection state signaling is generated in response to the second cross-network connection state signaling. The third cross-network connection state signaling contains the first PLMN hidden topology information, and the third cross-network connection state signaling is sent to the first PLMN so that the first PLMN responds to the third cross-network connection state signaling.

[0111] Optionally, the second cross-network connection state signaling is specifically a second UE context creation request signaling or a second UE context creation response signaling, and the third cross-network connection state signaling is specifically a PDU session context request; or,

[0112] The second cross-network connection state signaling is specifically the second type A PDU session context response signaling, and the third cross-network connection state signaling is specifically the PDU session update request.

[0113] Optionally, the network elements of this network include the Security Edge Protection Proxy (SEPP) network element, the first network function (NF) network element, and / or the second NF network element, and the method includes:

[0114] The SEPP network element of this network receives the second cross-network connection state signaling from the first PLMN and forwards the second cross-network connection state signaling to the first NF network element of this network;

[0115] The first NF network element of this network responds to the second cross-network connection state signaling to generate the first and third cross-network connection state signaling. The first and third cross-network connection state signaling contains the first PLMN hidden topology information taken from the second cross-network connection state signaling, and sends the first and third cross-network connection state signaling to the second NF network element or the SEPP network element of this network.

[0116] If the first and third cross-network connection state signaling is sent to the second NF network element of this network, the second NF network element of this network generates the second and third cross-network connection state signaling based on the first and third cross-network connection state signaling. The second and third cross-network connection state signaling contains the first PLMN hidden topology information taken from the first and third cross-network connection state signaling, and sends the second and third cross-network connection state signaling to the SEPP network element of this network.

[0117] The SEPP network element of this network performs topology hiding on the real topology information of this network that may be contained in the first or third cross-network connection state signaling or the second or third cross-network connection state signaling, so as to obtain the third cross-network connection state signaling and send the third cross-network connection state signaling to the first PLMN so that the first PLMN responds to the third cross-network connection state signaling.

[0118] Specifically, in this embodiment, since the second cross-network connection state signaling is obtained based on the first cross-network connection state signaling, it is a signaling proposed in this application that is different from the prior art. Therefore, the process of the second PLMN processing the second cross-network connection state signaling after it is sent to the second PLMN is also not present in the prior art.

[0119] Optionally, the method is applied to the local network elements of the first PLMN;

[0120] Cross-network connection-state signaling is processed based on real or hidden information related to the UE's connection-state service context in the first PLMN, to achieve continuous connection-state communication between the UE and the second PLMN, specifically including:

[0121] If the cross-network connection state signaling is a third cross-network connection state signaling from the second PLMN, and the third cross-network connection state signaling contains hidden topology information of the local network, which is obtained by the local network based on the real topology information of the local network in the connection state service context of the UE in the local network and sent to the second PLMN, then the hidden topology information of the local network in the third cross-network connection state signaling is used to perform topology restoration to obtain a fourth cross-network connection state signaling containing the real topology information of the local network, and the local network responds to the fourth cross-network connection state signaling.

[0122] Optionally, the third cross-network connection state signaling is the response of the second PLMN to the second cross-network connection state signaling from the first PLMN. The second cross-network connection state signaling is obtained by the local network security edge protection agent (SEPP) network element by topology hiding the local network real topology information in the first cross-network connection state signaling from the local network first network function (NF) network element. The first cross-network connection state signaling is generated by the local network first NF network element for the UE and contains the local network real topology information of the UE in the connection state service context of the local network. The UE's connection state service context in the local network is the UE's protocol data unit (PDU) session context in the local network. The local network real topology information is the real address of the local network second NF network element responsible for processing the local network PDU session for the UE.

[0123] Optionally, the network element in question is specifically a SEPP network element in question, and the method specifically includes:

[0124] Receive third cross-network connection state signaling from the second PLMN;

[0125] Replace the hidden address of the second NF network element in the third cross-network connection state signaling with the real address of the second NF network element in this network to obtain the fourth cross-network connection state signaling.

[0126] The fourth cross-network connection state signaling is sent to the second NF network element of this network, so that the second NF network element of this network responds to the fourth cross-network connection state signaling.

[0127] Specifically, in this embodiment, if the second PLMN returns the third cross-network connection state signaling to the first PLMN, according to the principles defined by 3GPP, the SEPP generally performs topology restoration on the third cross-network connection state signaling and forwards the restored fourth cross-network connection state signaling to the NF network element. Corresponding to the four scenarios of the first cross-network connection state signaling, there are also four scenarios for topology restoration:

[0128] 1) When a connected UE moves from its home network to its visited network, a cross-PLMN N2 handover occurs. If the home network has an I-SMF, the N38 interface between the V-SMF and I-SMF needs to cross the PLMN (N38-like interface). During the Retrieve SM Context process, the SEPP of the home network needs to perform topology hiding on the IP addresses in pduSessionRef, hSmfUri, or smfUri. In subsequent procedures, the SEPP of the home network needs to restore the topology hiding. If the home network does not have an I-SMF, the N16 interface between the V-SMF and H-SMF needs to cross the PLMN (N16-like interface). During the Retrieve SM Context process, the home network needs to perform topology hiding on the IP addresses in pduSessionRef, hSmfUri, or smfUri. In subsequent procedures, the SEPP of the home network needs to restore the topology hiding.Taking I-SMF as an example, the specific process is as follows: The home network's AMF sends a Namf_Communication_CreateUEContext request to the visited network's AMF; the vAMF sends an Nsmf_PDUSession_CreateSMContext request to the vSMF; the vSMF sends an Nsmf_PDUSession_ContextRequest (or Retrieve SM Context request) to the home network's I-SMF to obtain the SmContext; and the I-SMF returns an Nsmf_PDUSession_Context Response (or Retrieve SM Context) to the V-SMF. The `response` method passes the `SmContext` to the V-SMF. The `pduSessionRef`, `hSmfUri`, and `smfUri` contain the IP address information of the home network anchor point (SMF). If the home network's SEPP (producer SEPP) does not hide the IP addresses in `pduSessionRef`, `hSmfUri`, and `smfUri`, the home network's IP address information will be leaked to the visited network. Furthermore, the home and visited networks cannot communicate directly using IP addresses, causing subsequent signaling processes during the handover to fail, thus causing the entire handover process to fail. Therefore, the home network's SEPP (producer SEPP) needs to handle the `Retrieve SM Context`. The IP address information in pduSessionRef, hSmfUri, and smfUri in the response message is encrypted and replaced with the topology-hidden FQDN. This topology-hidden FQDN points to the home network's A-SMF (i.e., hSMF, the UE's Anchor-SMF in the home network, which is called hSMF relative to vSMF, and Anchor-SMF relative to I-SMF). In the subsequent V-SMF to H-SMF Nsmf_PDUSession_Update_Request (if the home network has I-SMF) or Nsmf_PDUSession_Create_Request (if the home network does not have I-SMF), the home network's SEPP needs to restore the topology-hidden FQDN of pduSessionRef and hSmfUri to the IP address so that it can be routed normally in the home network in subsequent processes.

[0129] 2) When a connected UE moves from the visited network to the home network, a cross-PLMN N2 handover occurs. If the home network has an I-SMF, the N38 interface between the V-SMF and I-SMF needs to cross the PLMN. During the Retrieve SM Context process, the FQDN in pduSessionRef, hSmfUri, or smfUri in the Nsmf_PDUSession_Context Response (or Retrieve SM Context response) returned by the v-SMF to the I-SMF is the topology-hidden FQDN. The SEPP of the home network needs to perform topology-hidden restoration on the FQDN in pduSessionRef, hSmfUri, or smfUri to restore it to IP address information. If the home network does not have an I-SMF, the N16 interface between the V-SMF and H-SMF needs to cross the PLMN. During the Retrieve SM Context process, the FQDN in pduSessionRef, hSmfUri, or smfUri needs to cross the PLMN. During the Context process, the FQDN in pduSessionRef, hSmfUri, or smfUri in the Nsmf_PDUSession_ContextResponse (or Retrieve SM Context response) returned by v-SMF to h-SMF is the topology-hidden FQDN. The SEPP of the home network needs to perform topology-hidden restoration on the FQDN in pduSessionRef, hSmfUri, or smfUri to restore it to IP address information.Taking I-SMF as an example, the specific process is as follows: The AMF (old AMF, consumer AMF) of the visited network sends a Namf_Communication_CreateUEContext request to the AMF (new AMF, producer AMF) of the home network; the vAMF sends an Nsmf_PDUSession_CreateSMContext request to the vSMF; the I-SMF sends an Nsmf_PDUSession_ContextRequest (or Retrieve SM Context request) to the v-SMF of the visited network to obtain the SmContext; and the v-SMF returns an Nsmf_PDUSession_Context Response (or Retrieve SM Context). The response passes the SmContext to the I-SMF, where pduSessionRef, hSmfUri, and smfUri point to the home network anchor point SMF, which is the topology-hidden FQDN. The home network's SEPP performs topology-hidden restoration on the FQDN in pduSessionRef, hSmfUri, and smfUri, restoring it to an IP address. If the FQDN is preserved, subsequent processes cannot be correctly routed within the local network. After the topology-hidden restoration by the home network's SEPP, in the subsequent message Nsmf_PDUSession_Update_Request (if the home network has an I-SMF) or Nsmf_PDUSession_Create_Request (if the home network does not have an I-SMF), the message can be correctly forwarded to the H-SMF within the home network (both I-SMF and A-SMF are NFs of the home network, and the N16a interface does not cross PLMNs and can communicate directly).

[0130] 3) When the UE moves from its home network to the visited network, a mobility registration update occurs, similar to the first scenario;

[0131] 4) When the UE moves from the visited network to the home network, a mobility registration update occurs, similar to the second scenario;

[0132] When I-SMF exists in the network, there are some alternative solutions: I-SMF can perform topology restoration without relying on hSEPP. The IP address of the smfURI brought by the AMF can be used to replace the FQDN in pduSessionRef before performing iSMF->aSMF interaction. This is because the UEcontext obtained by hAMF in the previous steps contains the smfURI parameter. This parameter is already the IP address information of the anchor SMF of the home network in the topology hiding and restoration of the UEcontext. It can replace the FQDN in pduSessionRef, so that the service will not fail in the scenario of inserting I-SMF in the home network. This alternative method is feasible, but it is not entirely consistent with the overall 3GPP principle of performing topology hiding and restoration through SEPP.

[0133] Optionally, the fourth cross-network connection state signaling is sent to the second NF network element of this network, specifically including:

[0134] The fourth cross-network connection state signaling is sent to the second NF network element of this network through the second cross-network connection state signaling communication interface of this network. The second cross-network connection state signaling communication interface of this network is a pre-established interface that forwards the signaling to be sent from the other network NF network element to the second NF network element of this network to the second NF network element of this network by the SEPP network element of this network.

[0135] Specifically, in this embodiment, the second cross-network connection state signaling communication interface of this network refers to the N16-type interface, N38-type interface, etc., which have been introduced above.

[0136] Optionally, the first NF network element of this network is specifically the hAMF network element belonging to the hPLMN, and the second NF network element of this network is specifically the hA-SMF network element of the hPLMN.

[0137] The method is applied to intermediate hI-SMF network elements belonging to hPLMN, and specifically includes:

[0138] Receive third cross-network connection state signaling;

[0139] The real address of the hA-SMF network element is obtained from the hAMF network element according to the third cross-network connection state signaling;

[0140] Replace the hidden address of the hA-SMF network element in the third cross-network connection state signaling with the real address of the obtained hA-SMF network element to obtain the fourth cross-network connection state signaling;

[0141] The fourth cross-network connection state signaling is sent to the hA-SMF network element so that the hA-SMF network element responds to the fourth cross-network connection state signaling.

[0142] Specifically, in this embodiment, this part corresponds to the alternative scheme of the topology restoration scheme applied to SEPP mentioned above. The I-SMF network element can obtain the real address of the hA-SMF network element from the hAMF network element based on the previously completed signaling process, as in the example above, or it can generate special signaling to obtain the real address of the hA-SMF network element from the hAMF network element.

[0143] Optionally, the first PLMN is the visiting vPLMN, and the second PLMN is the home hPLMN. The method is applied to the local security edge protection agent (hSEPP) network element of the hPLMN.

[0144] Cross-network connection-state signaling is processed based on real or hidden information related to the UE's connection-state service context in the first PLMN, to achieve continuous connection-state communication between the UE and the second PLMN, specifically including:

[0145] If the cross-network connection state signaling is a Type B Protocol Data Unit (PDU) session context response signaling, and the Type B PDU session context response signaling contains the UE's PDU session context in the vPLMN and the hidden address of the local network function (hNF) element in the hPLMN, then topology restoration is performed on the hidden address of the hNF element in the Type B PDU session context response signaling to obtain a Type B PDU session context response signaling containing the real topology address of the hNF element. The Type B PDU session context response signaling is then sent to the hNF element so that the hNF element can obtain the UE's PDU session context in the vPLMN from the Type B PDU session context response signaling.

[0146] Optionally, the first PLMN is the visiting vPLMN, and the second PLMN is the home hPLMN. The method is applied to the hI-SMF network element of the hPLMN local network intermediate session management function.

[0147] Cross-network connection-state signaling is processed based on real or hidden information related to the UE's connection-state service context in the first PLMN, to achieve continuous connection-state communication between the UE and the second PLMN, specifically including:

[0148] If the cross-network connection state signaling is a Type B PDU session context response signaling, and the Type B PDU session context response signaling contains the UE's PDU session context in the vPLMN and the hidden address of the local anchor point hA-SMF network element in the hPLMN, then topology restoration is performed on the hidden address of the hA-SMF network element in the Type B PDU session context response signaling to obtain a Type B PDU session context response signaling containing the real topology address of the hA-SMF network element. The Type B PDU session context response signaling is then sent to the hA-SMF network element so that the hA-SMF network element obtains the UE's PDU session context in the vPLMN from the Type B PDU session context response signaling.

[0149] Optionally, topology restoration is performed on the hidden address of the hA-SMF network element in the first Type B PDU session context response signaling to obtain the second Type B PDU session context response signaling containing the real topology address of the hA-SMF network element, specifically including:

[0150] The hA-SMF network element real address is obtained from the local mobility and access management function hAMF network element of hPLMN according to the first type B PDU session context response signaling;

[0151] Replace the hidden address of the hA-SMF network element in the first type B PDU session context response signaling with the obtained real address of the hA-SMF network element to obtain the second type B PDU session context response signaling.

[0152] Specifically, in this embodiment, the processing of the first type B PDU session context response signaling still corresponds to the topology restoration process performed by SEPP. The difference is that, unlike the topology restoration process performed by SEPP of the first PLMN, the SMF address of the second PLMN needs to be restored at this time. The SMF address of the first PLMN may not be carried in this signaling (because the subsequent PDU session update is only completed in the home network). During the inter-network communication process, the two networks will hide and restore the topology information of their respective ends. When the network after the move is the home network, the signaling for obtaining the PDU session context delivers the PDU session context in the network before the move to the home network. The home network needs to pre-select the SMF network element to process the PDU session. The address of the SMF network element will be delivered to the network before the move through certain prior signaling, so that the signaling returned by the network before the move points to the SMF network element. This is a specific method for obtaining the PDU session context, and this application is not limited to this method.

[0153] To illustrate the method described in this application more vividly, the following will be combined with... Figure 5-12 Several specific implementation examples are given.

[0154] Specific example 1:

[0155] like Figure 5 As shown, during inter-network mobility with HPLMN (in the scenario of inserting I-SMF) as the first PLMN and VPLMN as the second PLMN, the specific network elements involved include H-SEPP, H-AMF, HI-SMF, and HA-SMF of HPLMN, and V-SEPP, V-SMF, and V-AMF of VPLMN. When the UE moves from HPLMN to VPLMN in a connected state, inter-network communication is achieved through a handover preparation procedure. The inter-network interaction procedure is as follows:

[0156] Step 0: The source base station of the home network initiates a handover request (Handover Required) to the hAMF (case-sensitive and hyphens do not affect the meaning of the network element they refer to), which is a radio configuration handover request to switch the base station connected to the UE, i.e., handover. Figure 1 (N2 interface);

[0157] Step 1: (N14 Interface Message) The home network's hAMF (old AMF) passes the UEContext to the visited network's vAMF (new AMF) through the N14 interface across the PLMN. The hAMF sends a Namf_Communication_CreateUEContextRequest (first UE context creation request) message to hSEPP, which forwards it to the vAMF. The message carries the smContextRef field, which contains the IP address information of the user iSMF (the topology address obtained in the PDU session context).

[0158] Step 2: (N14 interface message) hSEPP performs topology hiding replacement on the IP address carried in the smContextRef field of Namf_Communication_CreateUEContext Request, replacing it with the hidden FQDN format pointing to iSMF, thus forming the second Create UE Context Request;

[0159] Step 3: (N14 interface message) hSEPP forwards the Namf_Communication_CreateUEContext Request (second UE context creation request) with hidden address to vSEPP, and vSEPP forwards the Namf_Communication_CreateUEContext Request with hidden address to vAMF;

[0160] Step 4: (N11 Interface Message) vAMF sends an Nsmf_PDUSession_CreateSMContextRequest message to vSMF, carrying the topology-hidden smContextRef;

[0161] Step 5: (N38 interface message) vSMF obtains SmContext based on the session context creation request, generates Nsmf_PDUSession_Context Request (or Retrieve SM Context request) (PDU session context request) to be sent to hiSMF, first processes it into the first PDU session context request through vSEPP and sends it to hSEPP, carrying smContextRef after topology hiding;

[0162] Step 6: (N38 interface message) hSEPP receives the first PDU session context request sent by vSEPP, performs a topology restoration operation (topology restoration) on the topology-hidden smContextRef, restores it to the IP address of iSMF, and forms the second PDU session context request;

[0163] Step 7: (N38 interface message) hSEPP forwards the smf_PDUSession_Context Request (or Retrieve SM Context request) (second PDU session context request) to H-iSMF;

[0164] Step 8: (N38 Interface Message) H-iSMF returns Nsmf_PDUSession_ContextResponse (or Retrieve SM Context response) (Type A PDU session context response, containing the PDU session context and the topology address obtained from the PDU session context) to V-SMF via H-SEPP, and passes SmContext to V-SMF, where pduSessionRef, smfUri (and / or hsmfUri) contain the IP address information of the home network anchor SMF (A-SMF) (the topology address obtained from the PDU session context); Note: According to the standard protocol, pduSessionRef and smfUri should be carried here, but it can also be one of the following: pduSessionRef and hsmfUri, pduSessionRef and smfUri and hsmfUri;

[0165] Step 9: (N38 Interface Message) hSEPP performs topology hiding on the IP address information in pduSessionRef and smfUri, or pduSessionRef and hsmfUri, or pduSessionRef and smfUri and hsmfUri in Nsmf_PDUSession_Context Response, and replaces it with the topology-hidden FQDN to form a second type A PDU session context response;

[0166] Step 10: (N38 interface message) hSEPP and vSEPP forward the Nsmf_PDUSession_ContextResponse with the hidden address to vSMF;

[0167] Step 11: (N16 Interface Message) The vSMF sends an Nsmf_PDUSession_Update Request (PDU Session Update Request) to the home network's H-SMF (A-SMF), carrying a pduSessionRef that has been topologically hidden. This request is processed by vSEPP into the first PDU session update request and then sent to hSEPP. Note: The smfUri or hsmfUri passed to the vSMF in steps 8-10 will be stored in the vSMF as context information for the session, used to replace the relevant parameters that the AMF passed to the VSMF in step 4.

[0168] Step 12: (N16 interface message) hSEPP performs topology hiding recovery on the pduSessionRef carried by Nsmf_PDUSession_Update Request, restoring it to the HSMF (ASMF) IP address to form the second PDU session update request;

[0169] Step 13: (N16 interface message) hSEPP forwards the restored Nsmf_PDUSession_Update Request (second PDU session update request) to HSMF (ASMF);

[0170] Step 14: (N16 Interface Message) HSMF (ASMF) replies to VSMF with a response message Nsmf_PDUSession_Update Response (PDU Session Update Response), which is then forwarded to VSMF via hSEPP and vSEPP;

[0171] Step 15: (N11 interface message, response to step 4) After updating the session, vSMF replies to vAMF with the response message Nsmf_PDUSession_CreateSMContext Response (create session context response);

[0172] Step 16: (N14 interface message, response to step 1) After receiving the response that the session creation is complete, vAMF sends the Namf_Communication_CreateUEContext Response message to hAMF.

[0173] Specific example 2:

[0174] like Figure 6 As shown, during inter-network mobility with HPLMN (in a scenario without I-SMF) as the first PLMN and VPLMN as the second PLMN, the specific network elements involved include H-SEPP, H-AMF, and H-SMF of HPLMN, and V-SEPP, V-SMF, and V-AMF of VPLMN. When the UE moves from HPLMN to VPLMN in a connected state, inter-network communication is achieved through a handover preparation procedure. The inter-network interaction procedure is as follows:

[0175] Step 0: The source base station of the home network initiates a handover request to hAMF (Handover Required);

[0176] Step 1: (N14 Interface Message) The home network's hAMF (old AMF) transmits the UEContext to the visited network's vAMF (new AMF) through the N14 interface across the PLMN. The hAMF sends a Namf_Communication_CreateUEContextRequest (first UE context creation request) message to the vAMF, which carries the smContextRef field, which contains the IP address information of the user hSMF. The message is first sent to hSEPP;

[0177] Step 2: (N14 interface message) hSEPP performs topology hiding replacement on the IP address carried in the smContextRef field of Namf_Communication_CreateUEContext Request, replacing it with the hidden FQDN format pointing to hSMF, forming the second Create UE Context message;

[0178] Step 3: (N14 interface message) hSEPP forwards the hidden Namf_Communication_CreateUEContextRequest (second UE context creation message) to vSEPP, and vSEPP forwards the hidden Namf_Communication_CreateUEContextRequest to vAMF;

[0179] Step 4: (N11 Interface Message) vAMF sends an Nsmf_PDUSession_CreateSMContext Request message to vSMF based on the second Create UE Context message, carrying the topology-hidden smContextRef;

[0180] Step 5: (N16 interface message) vSMF sends a request to hSMF to create a session context Nsmf_PDUSession_Context Request (or Retrieve SM Context request) (PDU session context request) to obtain SmContext, carrying smContextRef after topology hiding, and sends it to hSEPP as the first PDU session context request after being processed by vSEPP.

[0181] Step 6: (N38 interface message) hSEPP performs a topology-hidden recovery operation on smContextRef after topology hiding in the first PDU session context request, restoring it to the IP address of hSMF, and forming the second PDU session context request;

[0182] Step 7: (N16 interface message) hSEPP forwards the restored Nsmf_PDUSession_Context Request (or Retrieve SM Context request) (second PDU session context request) to hSMF;

[0183] Step 8: (N16 Interface Message) H-SMF returns Nsmf_PDUSession_ContextResponse (or Retrieve SM Context response) (Type A PDU session context response) to V-SMF via hSEPP, passing SmContext to V-SMF. pduSessionRef, smfUri (and / or hsmfUri) contain the IP address information of the home network anchor SMF (A-SMF\H-SMF). Note: According to existing standard protocols, pduSessionRef and smfUri should be carried here, but it can also be pduSessionRef and hsmfUri, or pduSessionRef, smfUri, and hsmfUri.

[0184] Step 9: (N16 Interface Message) hSEPP performs topology hiding on the IP address information in pduSessionRef and smfUri, or pduSessionRef and hsmfUri, or pduSessionRef and smfUri and hsmfUri in Nsmf_PDUSession_Context Response, and replaces it with the topology-hidden FQDN, forming a second type A PDU session context response;

[0185] Step 10: (16 Interface Messages) hSEPP forwards the topology-hidden Nsmf_PDUSession_ContextResponse (Type A PDU session context response) to vSMF via vSEPP;

[0186] Step 11: (N16 Interface Message) The vSMF sends an Nsmf_PDUSession_Create Request (PDU Session Update Request) to the H-SMF (A-SMF) of the home network, carrying the pduSessionRef which has been topologically hidden. This request is processed by vSEPP into the first PDU session update request and then sent to hSEPP. Note: The smfUri or hsmfUri passed to the vSMF in steps 8-10 will be stored in the vSMF as the context information for this session, which will be used to replace the relevant parameters that the AMF passed to the VSMF in step 4.

[0187] Step 12: (N16 interface message) hSEPP performs topology hiding recovery on the pduSessionRef carried by Nsmf_PDUSession_Create Request, restores it to the HSMF (ASMF) IP address, and forms the second PDU session update request;

[0188] Step 13: (N16 interface message) hSEPP forwards the recovered Nsmf_PDUSession_Update Request (second PDU session update request) to HSMF (ASMF);

[0189] Step 14: (N16 Interface Message) HSMF (ASMF) replies to VSMF with a response message Nsmf_PDUSession_Create Response (PDU session update response), which is then forwarded to VSMF via hSEPP and vSEPP;

[0190] Step 15: (N11 interface message, response to step 4) vSMF replies to vAMF with the response message Nsmf_PDUSession_CreateSMContext Response (session context creation response);

[0191] Step 16: (N14 interface message, response to step 1) vAMF sends Namf_Communication_CreateUEContext Response to hAMF.

[0192] Specific example 3:

[0193] like Figure 7 As shown, during inter-network mobility with VPLMN as the first PLMN and HPLMN (in scenarios with I-SMF) as the second PLMN, the specific network elements involved include V-SEPP, V-SMF, and V-AMF of VPLMN, and H-SEPP, HA-SMF, HI-SMF, and H-AMF of HPLMN. When the UE moves from VPLMN to HPLMN in a connected state, inter-network communication is achieved through a handover preparation procedure. The inter-network interaction procedure is as follows:

[0194] Step 0: The source base station of the visited network initiates a handover request to vAMF (Handover Required);

[0195] Step 1: (N14 Interface Message) The visited network's vAMF (old AMF) transmits the UEContext to the home network's hAMF (new AMF) via the N14 interface across the PLMN according to the handover request. The vAMF sends a Namf_Communication_CreateUEContext Request message to the hAMF, which carries the smContextRef field. This field contains the user vSMF's IP address information or FQDN. This message is first sent to vSEPP for processing. Note: For the visited network's vSMF, smContextRef may be either the vSMF's IP address or its FQDN. The FQDN is the original FQDN without hidden topology.

[0196] Step 2: (N14 interface message) vSEPP performs topology hiding replacement on the IP address or FQDN carried in the smContextRef field of Namf_Communication_CreateUEContext Request, replacing it with the hidden FQDN format pointing to vSMF, and the signaling is converted to the second Create UE Context Request;

[0197] Step 3: (N14 interface message) vSEPP forwards the Namf_Communication_CreateUEContext Request with the hidden address to hSEPP; hSEPP forwards the Namf_Communication_CreateUEContext Request to hAMF;

[0198] Step 4: (N11 Interface Message) hAMF sends an Nsmf_PDUSession_CreateSMContextRequest message to iSMF, carrying the topology-hidden smContextRef;

[0199] Step 5: (N38 interface message) iSMF sends Nsmf_PDUSession_ContextRequest (or Retrieve SM Context request) (first PDU session context request) to vSMF via hSEPP to obtain SmContext, and the signaling carries smContextRef after topology hiding;

[0200] Step 6: (N38 Interface Message) The first PDU session context request first undergoes a topology-hidden recovery operation on the topology-hidden smContextRef by vSEPP, restoring it to the vSMF IP address, thus forming the second PDU session context request;

[0201] Step 7: (N38 interface message) vSEPP forwards the restored smf_PDUSession_Context Request (or Retrieve SM Context request) to vSMF;

[0202] Step 8: (N38 Interface Message) vSMF returns Nsmf_PDUSession_ContextResponse (or Retrieve SM Context response) to iSMF via vSEPP (a Class B PDU session context response, containing the PDU session context, but not necessarily the topology address from the PDU session context), and passes the SmContext to iSMF. The pduSessionRef, smfUri (and / or hsmfUri) contain the IP address information of aSMF in the home network. vSEPP then forwards the Nsmf_PDUSession_Context... The response (a Type B PDU session context response, which does not hide the topology address obtained in the PDU session context, but may have other processing actions) is forwarded to hSEPP; Note: According to the standard protocol, pduSessionRef and hsmfUri should be carried here, but it can also be pduSessionRef and smfUri, pduSessionRef and smfUri and hsmfUri; the pduSessionRef and hsmfUri stored in vSMF are all FQDNs (hidden topology addresses of the second PLMN) that have been topology hidden by hSEPP of the home network.

[0203] Step 9: (N38 Interface Message) hSEPP performs topology hiding on the FQDN in pduSessionRef and smfUri, or pduSessionRef and hsmfUri, or pduSessionRef and smfUri and hsmfUri in Nsmf_PDUSession_Context Response, and restores it to the IP address of aSMF, forming a second type B PDU session context response;

[0204] Step 10: (N38 interface message) hSEPP forwards the Nsmf_PDUSession_Context Response (Type B PDU session context response) to iSMF;

[0205] Step 11: (N16a interface message) The iSMF sends an Nsmf_PDUSession_Update Request (PDU session update request) to the home network's H-SMF (A-SMF), carrying the pduSessionRef after topology hiding recovery. Note: If hSEPP performed topology hiding recovery in step 10, the smfUri or hsmfUri passed to the iSMF in steps 8-10 will be stored in the iSMF as the context information for this session, used to replace the relevant parameters brought to the iSMF by the AMF in step 4. An alternative solution is to perform topology hiding recovery without relying on hSEPP as the consumer. The IP of the smfUri brought by the AMF can be used to replace the FQDN in the pduSessionRef before performing iSMF->aSMF interaction. Theoretically, the parameters after topology hiding recovery are more reliable, and the topology hiding recovery scheme that hides step 10 is better.

[0206] Step 12: (N16a interface message) HSMF (aSMF) replies to iSMF with a response message Nsmf_PDUSession_Update Response (PDU session update response);

[0207] Step 13: (N11 interface message, response to step 4) iSMF replies to hAMF with the response message Nsmf_PDUSession_CreateSMContext Response (Session Context Creation Response);

[0208] Step 14: (N14 interface message, response to step 1) hAMF sends Namf_Communication_CreateUEContext Response message to vAMF (Create UE context response).

[0209] Specific example 4:

[0210] like Figure 8 As shown, during inter-network mobility with VPLMN as the first PLMN and HPLMN (in scenarios without I-SMF) as the second PLMN, the specific network elements involved include V-SEPP, V-SMF, and V-AMF of VPLMN, and H-SEPP, H-SMF, and H-AMF of HPLMN. When the UE moves from VPLMN to HPLMN in a connected state, inter-network communication is achieved through a handover preparation procedure. The inter-network interaction procedure is as follows:

[0211] Step 0: The source base station of the visited network initiates a handover request to vAMF (Handover Required);

[0212] Step 1: (N14 Interface Message) The visited network's vAMF (old AMF) passes the UEContext to the home network's hAMF (new AMF) via the N14 interface across the PLMN. The vAMF sends a Namf_Communication_CreateUEContextRequest (first UE context creation request) message to the hAMF, which carries the smContextRef field. This field contains the user vSMF's IP address information or FQDN. Note: For the visited network's vSMF, smContextRef may be either the vSMF's IP address or its FQDN. The FQDN is the original FQDN without hidden topology.

[0213] Step 2: (N14 interface message) vSEPP performs topology hiding replacement on the IP address or FQDN carried in the smContextRef field of Namf_Communication_CreateUEContext Request, replacing it with the hidden FQDN format pointing to vSMF, thus forming the second Create UE Context Request;

[0214] Step 3: (N14 interface message) vSEPP forwards the Namf_Communication_CreateUEContext Request to hSEPP; hSEPP forwards the Namf_Communication_CreateUEContext Request to hAMF;

[0215] Step 4: (N11 interface message) hAMF sends an Nsmf_PDUSession_CreateSMContextRequest message to aSMF (H-SMF), carrying the smContextRef after topology hiding;

[0216] Step 5: (N16 interface message) aSMF sends an Nsmf_PDUSession_Context Request (or Retrieve SM Context request) to vSMF to obtain the SmContext, carrying the topology-hidden smContextRef, which is then processed by hSEPP as the first PDU session context request and sent to vSEPP;

[0217] Step 6: (N16 interface message) vSEPP performs a topology-hidden recovery operation on the topology-hidden smContextRef, restoring it to the vSMF IP address, and forming a second PDU session context request;

[0218] Step 7: (N16 interface message) vSEPP forwards the smf_PDUSession_Context Request (or Retrieve SM Context request) to vSMF;

[0219] Step 8: (N16 Interface Message) vSMF returns an Nsmf_PDUSession_Context Response (or Retrieve SM Context response) to aSMF, passing the SmContext to a-SMF. The pduSessionRef, smfUri (and / or hsmfUri) contain the IP address information of aSMF in the home network (which has been hidden). vSEPP forwards the Nsmf_PDUSession_Context Response (Type B PDU session context response) to hSEPP. Note: According to the standard protocol, pduSessionRef and hsmfUri should be carried here, but it can also be pduSessionRef and smfUri, or pduSessionRef, smfUri, and hsmfUri. The pduSessionRef, hsmfUri, and smfUri stored by vSMF are all FQDNs that have been topology-hidden by hSEPP of the home network.

[0220] Step 9: (N16 Interface Message) hSEPP performs topology hiding on the FQDN in pduSessionRef and smfUri, or pduSessionRef and hsmfUri, or pduSessionRef and smfUri and hsmfUri in Nsmf_PDUSession_Context Response, and restores it to the IP address of aSMF, forming a second type B PDU session context response;

[0221] Step 10: (N16 Interface Message) hSEPP forwards the Nsmf_PDUSession_Context Response (Second Type B PDU Session Context Response) to aSMF;

[0222] Step 11: (N11 interface message, response to step 4) aSMF replies to hAMF with the response message Nsmf_PDUSession_CreateSMContext Response (Session Context Creation Response);

[0223] Step 12: (N14 interface message, response to step 1) hAMF sends Namf_Communication_CreateUEContext Response to vAMF.

[0224] Specific example 5:

[0225] like Figure 9 As shown, during inter-network mobility with HPLMN (in scenarios with I-SMF) as the first PLMN and VPLMN as the second PLMN, the specific network elements involved include H-SEPP, H-AMF, HI-SMF, and HA-SMF of HPLMN, and V-SEPP, V-SMF, and V-AMF of VPLMN. When a UE moves from HPLMN to VPLMN in a connected state, inter-network communication is achieved through the mobility registration update process. The inter-network interaction process is as follows:

[0226] Step 0: The source base station of the home network sends a redirection instruction to the UE, and the UE initiates a mobility registration update to the vAMF of the visited network;

[0227] Step 1: (N14 interface message) vAMF sends a Namf_Communication_UEContext Request (or Retrieve UEContext Request) message to hAMF (old AMF) to pass the UEContext to vAMF (new AMF) through the N14 interface across PLMN;

[0228] Step 2: (N14 interface message, response to Step 1) hAMF replies to vAMF with Namf_Communication_UEContext Response (or Retrieve UEContext Response) (first UE context creation response), the message carries the smContextRef field, which contains the IP address information of the user iSMF (existing in the original service context);

[0229] Step 3: (N14 interface message) hSEPP performs topology hiding replacement on the IP address carried in the smContextRef field of Namf_Communication_UEContext Response, replacing it with the hidden FQDN format pointing to iSMF, forming the second UE context creation response;

[0230] Step 4: (N14 interface message) hSEPP forwards the Namf_Communication_UEContext Response to vSEPP, and vSEPP forwards the Namf_Communication_UEContext Response to vAMF;

[0231] Step 5: (N11 interface message) vAMF sends an Nsmf_PDUSession_CreateSMContextRequest message to vSMF, carrying the smContextRef after topology hiding;

[0232] Step 6: (N38 interface message) vSMF sends Nsmf_PDUSession_ContextRequest (or Retrieve SM Context request) (first PDU session context request) to iSMF via vSEPP to obtain SmContext, carrying smContextRef after topology hiding;

[0233] Step 7: (N38 interface message) hSEPP performs a topology-hidden recovery operation on the topology-hidden smContextRef, restoring it to the iSMF IP address, and forming a second PDU session context request;

[0234] Step 8: (N38 interface message) hSEPP forwards the smf_PDUSession_Context Request (or Retrieve SM Context request) to H-iSMF;

[0235] Step 9: (N38 Interface Message) H-iSMF returns Nsmf_PDUSession_Context Response (or Retrieve SM Context response) (Type A PDU session context response) to V-SMF, passing SmContext to V-SMF. pduSessionRef, smfUri (and / or hsmfUri) contain the IP address information of the home network anchor SMF (A-SMF). Note: According to the standard protocol, pduSessionRef and smfUri should be carried here, but it can also be pduSessionRef and hsmfUri, or pduSessionRef, smfUri, and hsmfUri.

[0236] Step 10. (N38 Interface Message) hSEPP performs topology hiding on the IP address information in pduSessionRef and smfUri, or pduSessionRef and hsmfUri, or pduSessionRef and smfUri and hsmfUri in Nsmf_PDUSession_Context Response, and replaces it with the topology-hidden FQDN to form a second type A PDU session context response;

[0237] Step 11: (N38 interface message) hSEPP and vSEPP forward the Nsmf_PDUSession_Context Response to vSMF;

[0238] Step 12: (N16 interface message) The vSMF sends the Nsmf_PDUSession_Update Request (first PDU session update request) to the home network's H-SMF (A-SMF) via vSEPP, carrying the pduSessionRef that has been topologically hidden; Note: The smfUri or hsmfUri passed to the vSMF in steps 8-10 will be stored in the vSMF as the context information for this session, used to replace the relevant parameters that the AMF passed to the VSMF in step 4;

[0239] Step 13: (N16 interface message) hSEPP performs topology hiding recovery on the pduSessionRef carried by Nsmf_PDUSession_Update Request, restores it to the HSMF (ASMF) IP address, and forms the second PDU session update request.

[0240] Step 14: (N16 interface message) hSEPP forwards the Nsmf_PDUSession_Update Request to HSMF (ASMF);

[0241] Step 15: (N16 Interface Message) HSMF (ASMF) replies to VSMF with a response message Nsmf_PDUSession_Update Response (PDU Session Update Response), which is then forwarded to VSMF via hSEPP and vSEPP;

[0242] Step 16: (N11 interface message, response to step 4) vSMF replies to vAMF with the response message Nsmf_PDUSession_CreateSMContext Response (create session context response).

[0243] Specific example 6:

[0244] like Figure 10 As shown, during inter-network mobility with HPLMN (in a scenario without I-SMF) as the first PLMN and VPLMN as the second PLMN, the specific network elements involved include H-SEPP, H-AMF, and H-SMF of HPLMN, and V-SEPP, V-SMF, and V-AMF of VPLMN. When a UE moves from HPLMN to VPLMN in a connected state, inter-network communication is achieved through the mobility registration update process. The inter-network interaction process is as follows:

[0245] Step 0: The source base station of the home network sends a redirection instruction to the UE, and the UE initiates a mobility registration update to the vAMF of the visited network;

[0246] Step 1: (N14 interface message) vAMF sends Namf_Communication_UEContext Request (or Retrieve UEContext Request) message to hAMF (old AMF) to pass the UEContext to the visited network's vAMF (new AMF) via the N14 interface across the PLMN;

[0247] Step 2: (N14 interface message) hAMF replies to vAMF with Namf_Communication_UEContextResponse (or Retrieve UEContext Response) (first UE context creation response), the message carries the smContextRef field, which contains the IP address information of the user hSMF;

[0248] Step 3: (N14 interface message) hSEPP performs topology hiding replacement on the IP address carried in the smContextRef field of Namf_Communication_UEContext Response, replacing it with the hidden FQDN format pointing to hSMF, forming the second UE context creation response;

[0249] Step 4: (N14 interface message) hSEPP forwards the Namf_Communication_UEContext Response to vSEPP, and vSEPP forwards the Namf_Communication_UEContext Response to vAMF;

[0250] Step 5: (N11 interface message) vAMF sends an Nsmf_PDUSession_CreateSMContextRequest message to vSMF, carrying the smContextRef after topology hiding;

[0251] Step 6: (N16 interface message) vSMF sends Nsmf_PDUSession_ContextRequest (or Retrieve SM Context request) (first PDU session context request) to hSMF via vSEPP to obtain SmContext, carrying smContextRef after topology hiding;

[0252] Step 7: (N16 interface message) hSEPP performs a topology-hidden recovery operation on the topology-hidden smContextRef, restoring it to the IP address of hSMF, and forming a second PDU session context request;

[0253] Step 8: (N16 Interface Message) hSEPP forwards the smf_PDUSession_Context Request (or Retrieve SM Context request) to hSMF;

[0254] Step 9: (N16 Interface Message) H-SMF returns Nsmf_PDUSession_Context Response (or Retrieve SM Context response) (Type A PDU session context response) to V-SMF, passing SmContext to V-SMF. pduSessionRef, smfUri (and / or hsmfUri) contain the IP address information of the home network anchor SMF (A-SMF). Note: According to the standard protocol, pduSessionRef and smfUri should be carried here, but it can also be pduSessionRef and hsmfUri, or pduSessionRef, smfUri, and hsmfUri.

[0255] Step 10: (N16 Interface Message) hSEPP performs topology hiding on the IP address information in pduSessionRef and smfUri, or pduSessionRef and hsmfUri, or pduSessionRef and smfUri and hsmfUri in Nsmf_PDUSession_Context Response, and replaces it with the topology-hidden FQDN, forming a second type A PDU session context response;

[0256] Step 11: (N16 Interface Message) hSEPP and vSEPP forward the Nsmf_PDUSession_Context Response to vSMF;

[0257] Step 12: (N16 interface message) vSMF sends Nsmf_PDUSession_CreateRequest (first PDU session update request) to the home network's H-SMF, carrying the pduSessionRef which has been topologically hidden; Note: The smfUri or hsmfUri passed to vSMF in steps 8-10 will be stored in vSMF as the context information of the session, used to replace the relevant parameters that AMF passed to VSMF in step 4;

[0258] Step 13: (N16 interface message) hSEPP performs topology hiding recovery on the pduSessionRef carried by Nsmf_PDUSession_Create Request, restoring it to the IP address of HSMF, in order to obtain the second PDU session update request;

[0259] Step 14 (N16 Interface Message): hSEPP forwards the Nsmf_PDUSession_Create Request to HSMF;

[0260] Step 15: (N16 Interface Message) HSMF replies to VSMF with a response message Nsmf_PDUSession_CreateResponse (PDU session update response), which is then forwarded to VSMF via hSEPP and vSEPP;

[0261] Step 16 (N11 interface message, response to step 5) vSMF replies to vAMF with the response message Nsmf_PDUSession_CreateSMContext Response (create session context response).

[0262] Specific example 7:

[0263] like Figure 11 As shown, during inter-network mobility with VPLMN as the first PLMN and HPLMN (in scenarios with I-SMF) as the second PLMN, the specific network elements involved include V-SEPP, V-SMF, and V-AMF of VPLMN, and H-SEPP, HA-SMF, HI-SMF, and H-AMF of HPLMN. When a UE moves from VPLMN to HPLMN in a connected state, inter-network communication is achieved through the mobility registration update process. The inter-network interaction process is as follows:

[0264] Step 0: The source base station of the visited network sends a redirection instruction to the UE, and the UE sends a mobility registration update to its home network;

[0265] Step 1: (N14 Interface Message) In order to request the visited network's vAMF (old AMF) to pass the UEContext to the home network's hAMF (new AMF) through the N14 interface across the PLMN, the hAMF sends a Namf_Communication_UEContextRequest (Create UE Context Request) message to the vAMF;

[0266] Step 2: (N14 Interface Message) The vAMF returns a Namf_Communication_UEContextResponse (First UE Context Creation Response) message to the hAMF. The message carries an smContextRef field, which contains the user vSMF's IP address information or FQDN. Note: For the vSMF, smContextRef may be either the vSMF's IP address or its FQDN. The FQDN is the original FQDN without hidden topology.

[0267] Step 3: (N14 interface message) vSEPP performs topology hiding replacement on the IP address or FQDN carried in the smContextRef field of Namf_Communication_CreateUEContext Response, replacing it with the hidden FQDN format pointing to vSMF, forming the second Create UE Context response;

[0268] Step 4: (N14 interface message) vSEPP forwards the Namf_Communication_CreateUEContext Response to hSEPP, and hSEPP forwards the Namf_Communication_CreateUEContext Response to hAMF;

[0269] Step 5: (N11 interface message) hAMF sends an Nsmf_PDUSession_CreateSMContextRequest message to iSMF, carrying the smContextRef after topology hiding;

[0270] Step 6: (N38 interface message) iSMF sends Nsmf_PDUSession_ContextRequest (or Retrieve SM Context request) (first PDU session context request) to vSMF via hSEPP to obtain SmContext, carrying smContextRef after topology hiding;

[0271] Step 7: (N38 interface message) vSEPP receives the first PDU session context request sent by hSEPP, performs a topology-hidden recovery operation on the topology-hidden smContextRef, restores it to the IP address of vSMF, and forms the second PDU session context request;

[0272] Step 8: (N38 interface message) vSEPP forwards the Nsmf_PDUSession_Context Request (or Retrieve SM Context request) (which has been converted into a second PDU session context request) to vSMF;

[0273] Step 9: (N38 Interface Message) vSMF returns Nsmf_PDUSession_ContextResponse (or Retrieve SM Context response) (Type B PDU session context response) to iSMF via vSEPP, passing SmContext to iSMF. pduSessionRef, smfUri (and / or hsmfUri) contain the IP address information of aSMF in the home network (carried in the aforementioned PDU session context request). vSEPP forwards the Nsmf_PDUSession_Context Response to hSEPP. Note: According to the standard protocol, pduSessionRef and hsmfUri should be carried here, but it can also be pduSessionRef and smfUri, or pduSessionRef, smfUri, and hsmfUri. The pduSessionRef, hsmfUri, and smfUri stored by vSMF are all FQDNs that have undergone topology hiding by hSEPP of the home network.

[0274] Step 10: (N38 interface message) hSEPP performs topology hiding on the FQDN in pduSessionRef and smfUri, or pduSessionRef and hsmfUri or pduSessionRef and smfUri and hsmfUri in Nsmf_PDUSession_Context Response, and restores it to the IP address of aSMF, forming a second type B PDU session context response;

[0275] Step 11: (N38 interface message) hSEPP forwards the Nsmf_PDUSession_Context Response (Type B PDU session context response) to iSMF;

[0276] Step 12: (N16a interface message) iSMF sends an Nsmf_PDUSession_Update Request (PDU session update request) to the home network's H-SMF (A-SMF), carrying the pduSessionRef after topology hiding recovery; Note: If hSEPP performed topology hiding recovery in step 11, the smfUri or hsmfUri passed from vSMF to iSMF will be stored in iSMF as the context information of the session, used to replace the relevant parameters brought to iSMF by AMF in step 4; An alternative solution is to perform topology hiding recovery without relying on hSEPP when acting as the consumer, and use the IP of the smfUri brought by AMF to replace the FQDN in pduSessionRef before performing iSMF->aSMF interaction. Theoretically, the parameters after topology hiding recovery are more reliable, and the topology hiding recovery scheme that hides step 10 is better;

[0277] Step 13: (N16a interface message) HSMF (aSMF) replies to iSMF with a response message Nsmf_PDUSession_Update Response (PDU session update response);

[0278] Step 14: (N11 interface message, response to step 4) iSMF replies to hAMF with the response message Nsmf_PDUSession_CreateSMContext Response (create session context response).

[0279] Specific example 8:

[0280] like Figure 12As shown, during inter-network mobility with VPLMN as the first PLMN and HPLMN (in scenarios without I-SMF) as the second PLMN, the specific network elements involved include V-SEPP, V-SMF, and V-AMF of VPLMN, and H-SEPP, H-SMF, and H-AMF of HPLMN. When a UE moves from VPLMN to HPLMN in a connected state, inter-network communication is achieved through the mobility registration update process. The inter-network interaction process is as follows:

[0281] Step 0: The source base station of the visited network sends a redirection instruction to the UE, and the UE sends a mobility registration update to its home network;

[0282] Step 1: (N14 Interface Message) In order for the visited network's vAMF (old AMF) to pass the UEContext to the home network's hAMF (new AMF) through the N14 interface across the PLMN, the hAMF sends a Namf_Communication_UEContextRequest (Create UE Context Request) message to the vAMF;

[0283] Step 2: (N14 Interface Message) The vAMF returns a Namf_Communication_UEContextResponse (First UE Context Creation Response) message to the hAMF. The message carries an smContextRef field, which contains the user vSMF's IP address information or FQDN. Note: For the vSMF, smContextRef may be either the vSMF's IP address or its FQDN. The FQDN is the original FQDN without hidden topology.

[0284] Step 3: (N14 interface message) vSEPP performs topology hiding replacement on the IP address or FQDN carried in the smContextRef field of Namf_Communication_CreateUEContext Response, replacing it with the hidden FQDN format pointing to vSMF, forming the second Create UE Context response;

[0285] Step 4: (N14 interface message) vSEPP forwards Namf_Communication_CreateUEContext Response (second UE context creation response) to hSEPP, and hSEPP forwards Namf_Communication_CreateUEContextResponse to hAMF;

[0286] Step 5: (N11 interface message) hAMF sends an Nsmf_PDUSession_CreateSMContextRequest message to aSMF, carrying the smContextRef after topology hiding;

[0287] Step 6: (N16 interface message) aSMF sends Nsmf_PDUSession_ContextRequest (or Retrieve SM Context request) (first PDU session context request) to vSMF via hSEPP and vSEPP to obtain SmContext, carrying smContextRef after topology hiding;

[0288] Step 7: (N16 interface message) vSEPP performs a topology-hidden recovery operation on the topology-hidden smContextRef, restoring it to the vSMF IP address, and forming a second PDU session context request;

[0289] Step 8: (N16 interface message) vSEPP forwards the Nsmf_PDUSession_Context Request (or Retrieve SM Context request) (second PDU session context request) to vSMF;

[0290] Step 9: (N16 Interface Message) vSMF returns an Nsmf_PDUSession_Context Response (or Retrieve SM Context response) (Type B PDU Session Context Response) to aSMF via vSEPP and hSEPP, passing the SmContext to aSMF. The pduSessionRef, smfUri (and / or hsmfUri) contain the IP address information of aSMF in the home network. vSEPP forwards the Nsmf_PDUSession_Context Response to hSEPP. Note: According to the standard protocol, pduSessionRef and hsmfUri should be carried here, but it can also be pduSessionRef and smfUri, or pduSessionRef, smfUri, and hsmfUri. The pduSessionRef, hsmfUri, and smfUri stored by vSMF are all FQDNs that have undergone topology hiding by hSEPP of the home network.

[0291] Step 10: (N16 Interface Message) hSEPP performs topology hiding on the FQDN in pduSessionRef and smfUri, or pduSessionRef and hsmfUri, or pduSessionRef and smfUri and hsmfUri in Nsmf_PDUSession_Context Response, and restores it to the IP address of aSMF, forming a second type B PDU session context response;

[0292] Step 11: (N16 interface message) hSEPP forwards the Nsmf_PDUSession_Context Response (Type B PDU session context response) to aSMF;

[0293] Step 12: (N11 interface message, response to step 5) iSMF replies to hAMF with the response message Nsmf_PDUSession_CreateSMContext Response (create session context response).

[0294] Example 2:

[0295] like Figure 13 As shown, Embodiment 2 of the present invention provides an inter-network communication device, comprising:

[0296] Module 1 is used to acquire cross-network connection state signaling of a user equipment (UE) that has moved from the first PLMN to the second PLMN in a connected state. The cross-network connection state signaling contains real or hidden information related to the connection state service context of the UE in the first PLMN.

[0297] Processing module 2, connected to acquisition module 1, is used to process cross-network connection state signaling based on real or hidden information related to the connection state service context of the UE in the first PLMN, so as to realize continuous connection state communication between the UE in the first PLMN and the second PLMN.

[0298] Optionally, the device is specifically a local network function (NF) network element or a local network security edge protection agent (SEPP) network element of a first PLMN or a second PLMN, or a first PLMN or a second PLMN.

[0299] Optionally, the real or hidden information related to the UE's connection-state service context in the first PLMN specifically includes:

[0300] The first PLMN real topology information of the UE in the first PLMN connected-state service context, or the first PLMN hidden topology information obtained by topology hiding the first PLMN real topology information of the UE in the first PLMN connected-state service context, and / or the UE in the first PLMN connected-state service context.

[0301] Optionally, processing module 2 is specifically used for:

[0302] If the cross-network connection state signaling is the first cross-network connection state signaling, and the first cross-network connection state signaling contains the first PLMN real topology information of the UE in the connection state service context of the first PLMN, then topology hiding is performed on the first PLMN real topology information in the first cross-network connection state signaling to obtain the second cross-network connection state signaling containing the first PLMN hidden topology information, so that the second PLMN responds to the second cross-network connection state signaling.

[0303] Optionally, the first cross-network connection state signaling is generated for the UE by the first network function (NF) element of the first PLMN, the connection state service context of the UE in the first PLMN is the protocol data unit (PDU) session context of the UE in the first PLMN, and the real topology information of the first PLMN is the real address of the second NF element of the first PLMN responsible for processing the PDU session of the first PLMN for the UE.

[0304] Optional:

[0305] The format of the real address of the second NF network element of the first PLMN is Internet Protocol IP address or Fully Qualified Domain Name (FQDN);

[0306] The hidden topology information of the first PLMN is specifically the hidden address of the second NF network element of the first PLMN in FQDN format, which corresponds to the real address of the second NF network element of the first PLMN.

[0307] Optionally, the device is the first NF network element of the first PLMN;

[0308] Processing module 2 specifically includes:

[0309] The first sending unit is configured to send the first cross-network connection state signaling to the local network security edge protection agent (SEPP) network element, so that the local network SEPP network element performs topology hiding of the real address of the local network second NF network element in the first cross-network connection state signaling, thereby obtaining the second cross-network connection state signaling containing the hidden address of the local network second NF network element, and sends the second cross-network connection state signaling to the second PLMN, so that the second PLMN responds to the second cross-network connection state signaling.

[0310] Optionally, the first sending unit specifically includes a first cross-network connection state signaling communication interface of this network, used for:

[0311] The first cross-network connection state signaling is sent to the SEPP network element of this network through the first cross-network connection state signaling communication interface of this network. The first cross-network connection state signaling communication interface of this network is a pre-established interface through which the first NF network element of this network transfers the signaling to be sent to the NF network element of another network to the SEPP network element of this network.

[0312] Optionally, the device is the first NF network element of the local network, and specifically the local network mobility and access management function (AMF) network element of the first PLMN, and the second NF network element of the local network is specifically the local network session management function (SMF) network element.

[0313] Module 1 is specifically used for: if the local AMF network element receives a radio configuration handover request sent by the local base station for a UE that has moved from the local network to another network in a connected state, then generates a first Create UE Context Request signaling to be sent to the second PLMN according to the radio configuration handover request. The first Create UE Context Request signaling contains the real address of the local SMF network element of the UE in the local PDU session context.

[0314] The first sending unit is specifically used for: sending the first Create UE Context Request signaling to the local SMF network element, so that the local SEPP network element performs topology hiding of the real address of the local SMF network element in the first Create UE Context Request signaling, thereby obtaining a second Create UE Context Request signaling containing the hidden address of the local SMF network element, and sending the second Create UE Context Request signaling to the second PLMN, so that the second PLMN responds to the second Create UE Context Request signaling.

[0315] Optionally, the device is the first NF network element of this network, specifically the intermediate hI-SMF network element of the first PLMN and belonging to the hPLMN, and the second NF network element of this network is specifically the anchor point hA-SMF network element of the hPLMN; or, the device is the first NF network element of this network, specifically the h-SMF network element of the first PLMN and belonging to the hPLMN, and the second NF network element of this network is specifically the h-SMF network element of the hPLMN.

[0316] Module 1 is specifically used for: if the UE moves from the hPLMN to the visited vPLMN in a connected state, and the hI-SMF network element / h-SMF network element receives a PDU session context request signaling sent by the vPLMN to the UE based on the second Create UE Context Request signaling from the hPLMN, then the hI-SMF network element / h-SMF network element generates a first type A PDU session context response signaling to be sent to the vPLMN based on the PDU session context request signaling. The first type A PDU session context response signaling contains the real address of the hA-SMF network element / h-SMF network element in the UE's PDU session context in this network.

[0317] The first sending unit is specifically used for: the hI-SMF network element / h-SMF network element sending the first Type A PDU session context response signaling to the local SEPP network element, so that the local SEPP network element performs topology hiding on the real address of the hI-SMF network element / h-SMF network element in the first Type A PDU session context response signaling to obtain the second Type A PDU session context response signaling containing the hidden address of the hI-SMF network element / h-SMF network element, and sends the second Type A PDU session context response signaling to the vPLMN, so that the vPLMN responds to the second Type A PDU session context response signaling.

[0318] Optionally, the device is the first NF network element of the local network, and specifically the local network mobility and access management function (AMF) network element of the first PLMN, and the second NF network element of the local network is specifically the local network session management function (SMF) network element.

[0319] Module 1 is specifically used for: if the local AMF network element receives a UE context creation request sent by the second PLMN for the UE, then generates a first UE context creation response signaling to be sent to the second PLMN according to the UE context creation request. The first UE context creation response signaling contains the real address of the local SMF network element in the local PDU session context of the UE.

[0320] The first sending unit is specifically used for: sending the first Create UE Context Response signaling to the local SMF network element, so that the local SEPP network element performs topology hiding on the real address of the local SMF network element in the first Create UE Context Response signaling to obtain the second Create UE Context Response signaling containing the hidden address of the local SMF network element, and sending the second Create UE Context Response signaling to the second PLMN, so that the second PLMN responds to the second Create UE Context Response signaling.

[0321] Optionally, the device is the first NF network element of this network, specifically the intermediate hI-SMF network element of the first PLMN and belonging to the hPLMN, and the second NF network element of this network is specifically the anchor point hA-SMF network element of the hPLMN; or, the device is the first NF network element of this network, specifically the h-SMF network element of the first PLMN and belonging to the hPLMN, and the second NF network element of this network is specifically the h-SMF network element of the hPLMN.

[0322] Module 1 is specifically used for: if the UE moves from the hPLMN to the visited vPLMN in a connected state, and the hI-SMF network element / h-SMF network element receives a PDU session context request signaling sent by the vPLMN to the UE based on the second Create UE Context Response signaling from the hPLMN, then the hI-SMF network element / h-SMF network element generates a first type A PDU session context response signaling to be sent to the vPLMN based on the PDU session context request signaling. The first type A PDU session context response signaling contains the real address of the hA-SMF network element / h-SMF network element in the UE's PDU session context in this network.

[0323] The first sending unit is specifically used for: the hI-SMF network element / h-SMF network element sending the first Type A PDU session context response signaling to the local SEPP network element, so that the local SEPP network element performs topology hiding on the real address of the hI-SMF network element / h-SMF network element in the first Type A PDU session context response signaling to obtain the second Type A PDU session context response signaling containing the hidden address of the hI-SMF network element / h-SMF network element, and sends the second Type A PDU session context response signaling to the vPLMN, so that the vPLMN responds to the second Type A PDU session context response signaling.

[0324] Optionally, the device is a local security edge protection agent (SEPP) network element of the first PLMN;

[0325] Processing module 2 specifically includes:

[0326] The first topology hiding unit is used to perform topology hiding on the real address of the second NF network element in the first cross-network connection state signaling from the first NF network element of the local network, so as to obtain the second cross-network connection state signaling containing the hidden address of the second NF network element of the local network, and send the second cross-network connection state signaling to the second PLMN so that the second PLMN responds to the second cross-network connection state signaling.

[0327] Optionally, the processing module 2 of the SEPP network element of the first PLMN further includes a first receiving unit, which is used to receive the first cross-network connection state signaling from the first NF network element of the same network through the first cross-network connection state signaling communication interface of the same network. The first cross-network connection state signaling communication interface of the same network is a pre-established interface through which the first NF network element of the same network transfers the signaling to be sent to the NF network element of another network to the SEPP network element of the same network.

[0328] Optional:

[0329] The first NF network element in this network is specifically the Mobility and Access Management Function (AMF) network element; the second NF network element in this network is specifically the Session Management Function (SMF) network element; and the first cross-network connection state signaling is specifically the first UE context creation request signaling or the first UE context creation response signaling; or...

[0330] The first NF network element of this network is specifically the intermediate hI-SMF network element belonging to the hPLMN, and the second NF network element of this network is specifically the anchor hA-SMF network element of the hPLMN. Alternatively, the first NF network element of this network is specifically the h-SMF network element of the hPLMN, and the second NF network element of this network is specifically the h-SMF network element of the hPLMN. The first cross-network connection state signaling is specifically the first Class A PDU session context response signaling.

[0331] Optionally, the first topological hiding unit specifically includes:

[0332] The first address extraction subunit is used to extract the real address of the second NF network element of this network from the first cross-network connection state signaling from the first NF network element of this network, which is in the format of Internet Protocol IP address or Fully Qualified Domain Name (FQDN).

[0333] The first symmetric encryption subunit is used to perform topological hiding of the real address of the second NF network element of this network based on the symmetric encryption algorithm, and convert the encryption result into the hidden address of the second NF network element of this network in the format of FQDN;

[0334] The first address replacement subunit is used to replace the real address of the second NF network element in the first cross-network connection state signaling with the hidden address of the second NF network element in the local network, so as to obtain the second cross-network connection state signaling.

[0335] Optionally, the device is the first NF network element of the second PLMN;

[0336] Processing module 2 specifically includes:

[0337] The second sending unit is configured to request the local network security edge protection agent (SEPP) network element to initiate a service discovery request to the first PLMN according to the first cross-network connection state signaling request, so that the local network SEPP network element receives the service discovery response sent by the first PLMN according to the service discovery request;

[0338] The second receiving unit is used to receive the first PLMN hidden topology information in the service discovery response sent by the SEPP network element of this network.

[0339] The second replacement unit is used to replace the real topology information of the first PLMN in the first cross-network connection state signaling with the hidden topology information of the first PLMN to obtain the second cross-network connection state signaling, and to respond to the second cross-network connection state signaling in the local network.

[0340] Optionally, the second transmitting unit is specifically used for:

[0341] Determine whether the first cross-network connection state signaling comes from a different network. If so, determine whether the first cross-network connection state signaling contains the real address of the NF network element of the different network in the Internet Protocol IP format. If so, request the SEPP network element of this network to initiate a service discovery request to the first PLMN from which the first cross-network connection state signaling comes.

[0342] Optionally, the device is a local network element of the second PLMN;

[0343] The processing module is specifically used for:

[0344] If the cross-network connection state signaling is the second cross-network connection state signaling, and the second cross-network connection state signaling contains the first PLMN hidden topology information obtained by topology hiding the first PLMN real topology information in the connection state service context of the UE in the first PLMN, then the third cross-network connection state signaling is generated in response to the second cross-network connection state signaling. The third cross-network connection state signaling contains the first PLMN hidden topology information, and the third cross-network connection state signaling is sent to the first PLMN so that the first PLMN responds to the third cross-network connection state signaling.

[0345] Optionally, the second cross-network connection state signaling is specifically a second UE context creation request signaling or a second UE context creation response signaling, and the third cross-network connection state signaling is specifically a PDU session context request; or,

[0346] The second cross-network connection state signaling is specifically the second type A PDU session context response signaling, and the third cross-network connection state signaling is specifically the PDU session update request.

[0347] Optionally, the device specifically includes the local network security edge protection agent (SEPP) network element of the second PLMN, the local network first network function (NF) network element, and / or the local network second NF network element;

[0348] Module 1 is specifically used for: receiving the second cross-network connection state signaling from the first PLMN by the SEPP network element of this network, and forwarding the second cross-network connection state signaling to the first NF network element of this network;

[0349] Processing module 2 specifically includes:

[0350] The third generation unit is used to generate first and third cross-network connection state signaling in response to the second cross-network connection state signaling from the first NF network element of this network. The first and third cross-network connection state signaling contain the first PLMN hidden topology information taken from the second cross-network connection state signaling, and send the first and third cross-network connection state signaling to the second NF network element or the SEPP network element of this network.

[0351] If the first and third cross-network connection state signaling is sent to the second NF network element of this network, the second NF network element of this network generates the second and third cross-network connection state signaling based on the first and third cross-network connection state signaling. The second and third cross-network connection state signaling contains the first PLMN hidden topology information taken from the first and third cross-network connection state signaling, and sends the second and third cross-network connection state signaling to the SEPP network element of this network.

[0352] The second cross-network sending unit is used to perform topology hiding on the real topology information of the local network that may be contained in the first or third cross-network connection state signaling or the second or third cross-network connection state signaling by the local SEPP network element, so as to obtain the third cross-network connection state signaling, and send the third cross-network connection state signaling to the first PLMN so that the first PLMN responds to the third cross-network connection state signaling.

[0353] Optionally, the device is a local network element of the first PLMN;

[0354] Processing module 2 is specifically used for:

[0355] If the cross-network connection state signaling is a third cross-network connection state signaling from the second PLMN, and the third cross-network connection state signaling contains hidden topology information of the local network, which is obtained by the local network based on the real topology information of the local network in the connection state service context of the UE in the local network and sent to the second PLMN, then the hidden topology information of the local network in the third cross-network connection state signaling is used to perform topology restoration to obtain a fourth cross-network connection state signaling containing the real topology information of the local network, and the local network responds to the fourth cross-network connection state signaling.

[0356] Optionally, the third cross-network connection state signaling is the response of the second PLMN to the second cross-network connection state signaling from the first PLMN. The second cross-network connection state signaling is obtained by the local network security edge protection agent (SEPP) network element by topology hiding the local network real topology information in the first cross-network connection state signaling from the local network first network function (NF) network element. The first cross-network connection state signaling is generated by the local network first NF network element for the UE and contains the local network real topology information of the UE in the connection state service context of the local network. The UE's connection state service context in the local network is the UE's protocol data unit (PDU) session context in the local network. The local network real topology information is the real address of the local network second NF network element responsible for processing the local network PDU session for the UE.

[0357] Optionally, the device is a local network element, and specifically a local network SEPP element of the first PLMN;

[0358] Module 1 is specifically used for: receiving third cross-network connection state signaling from the second PLMN;

[0359] Processing module 2 specifically includes:

[0360] The first topology restoration unit is used to replace the hidden address of the second NF network element in the third cross-network connection state signaling with the real address of the second NF network element in the local network to obtain the fourth cross-network connection state signaling.

[0361] The fourth sending unit is used to send the fourth cross-network connection state signaling to the second NF network element of this network, so that the second NF network element of this network can respond to the fourth cross-network connection state signaling.

[0362] Optionally, the fourth sending unit specifically includes the second cross-network connection state signaling communication interface of this network, used for:

[0363] The fourth cross-network connection state signaling is sent to the second NF network element of this network through the second cross-network connection state signaling communication interface of this network. The second cross-network connection state signaling communication interface of this network is a pre-established interface that forwards the signaling to be sent from the other network NF network element to the second NF network element of this network to the second NF network element of this network by the SEPP network element of this network.

[0364] Optionally, the first NF network element of this network is specifically the hAMF network element belonging to the hPLMN, and the second NF network element of this network is specifically the hA-SMF network element of the hPLMN.

[0365] The device is specifically an intermediate hI-SMF network element belonging to the first PLMN and belonging to the hPLMN;

[0366] Module 1 is specifically used for: receiving third cross-network connection state signaling;

[0367] Processing module 2 specifically includes:

[0368] The fifth address acquisition unit is used to obtain the real address of the hA-SMF network element from the hAMF network element according to the third cross-network connection state signaling;

[0369] The fifth address replacement unit is used to replace the hidden address of the hA-SMF network element in the third cross-network connection state signaling with the real address of the obtained hA-SMF network element, so as to obtain the fourth cross-network connection state signaling;

[0370] The fifth sending unit is used to send the fourth cross-network connection state signaling to the hA-SMF network element so that the hA-SMF network element responds to the fourth cross-network connection state signaling.

[0371] Optionally, the first PLMN is a visiting vPLMN, the second PLMN is a home hPLMN, and the device is specifically a local security edge protection agent (hSEPP) network element of the hPLMN.

[0372] Processing module 2 is specifically used for:

[0373] If the cross-network connection state signaling is a Type B Protocol Data Unit (PDU) session context response signaling, and the Type B PDU session context response signaling contains the UE's PDU session context in the vPLMN and the hidden address of the local network function (hNF) element in the hPLMN, then topology restoration is performed on the hidden address of the hNF element in the Type B PDU session context response signaling to obtain a Type B PDU session context response signaling containing the real topology address of the hNF element. The Type B PDU session context response signaling is then sent to the hNF element so that the hNF element can obtain the UE's PDU session context in the vPLMN from the Type B PDU session context response signaling.

[0374] Optionally, the first PLMN is the visiting vPLMN, the second PLMN is the home hPLMN, and the device is specifically the hI-SMF network element of the hPLMN local network intermediate session management function.

[0375] Processing module 2 is specifically used for:

[0376] If the cross-network connection state signaling is a Type B PDU session context response signaling, and the Type B PDU session context response signaling contains the UE's PDU session context in the vPLMN and the hidden address of the local anchor point hA-SMF network element in the hPLMN, then topology restoration is performed on the hidden address of the hA-SMF network element in the Type B PDU session context response signaling to obtain a Type B PDU session context response signaling containing the real topology address of the hA-SMF network element. The Type B PDU session context response signaling is then sent to the hA-SMF network element so that the hA-SMF network element obtains the UE's PDU session context in the vPLMN from the Type B PDU session context response signaling.

[0377] Optionally, processing module 2 specifically includes:

[0378] The sixth address acquisition unit is used to obtain the real address of the hA-SMF network element from the local network mobility and access management function hAMF network element of the hPLMN according to the first type B PDU session context response signaling;

[0379] The sixth address replacement unit is used to replace the hidden address of the hA-SMF network element in the first type B PDU session context response signaling with the real address of the obtained hA-SMF network element, so as to obtain the second type B PDU session context response signaling.

[0380] Example 3:

[0381] like Figure 14 As shown, the present invention provides an electronic device, comprising:

[0382] Memory 10, on which a program is stored;

[0383] When the processor 20 runs the program stored in the memory 10, the processor 20 executes the inter-network communication method as described in Embodiment 1.

[0384] The memory 10 is connected to the processor 20. The memory 10 can be a flash memory, a read-only memory, or another type of memory. The processor 20 can be a central processing unit or a microcontroller.

[0385] Example 4:

[0386] Embodiment 4 of the present invention provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, it implements the inter-network communication method as described in Embodiment 1.

[0387] The computer-readable storage medium includes volatile or non-volatile, removable or non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, computer program modules, or other data). Computer-readable storage media include, but are not limited to, RAM (Random Access Memory), ROM (Read-Only Memory), EEPROM (Electrically Erasable Programmable Read-Only Memory), flash memory or other memory technologies, CD-ROM (Compact Disc Read-Only Memory), DVD or other optical disc storage, cartridges, magnetic tapes, disk storage or other magnetic storage devices, or any other medium that can be used to store desired information and is accessible to a computer.

[0388] Embodiments 1-4 of the present invention provide an inter-network communication method, an inter-network communication device, an electronic device, and a computer-readable storage medium. When a UE moves from a first PLMN to a second PLMN in a connected state, it acquires cross-network connected state signaling containing information related to the connected state service context of the UE in the first PLMN. By processing the cross-network connected state signaling, it ensures that the UE's communication service in the first PLMN continues in the second PLMN, thereby realizing continuous inter-network communication when the UE moves across networks in a connected state, ensuring user communication quality, and improving user experience.

[0389] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. An inter-network communication method, characterized in that, Applied to public land mobile networks (PLMNs) or their network elements, including: Acquire cross-network connection state signaling of a user equipment (UE) that has moved from the first PLMN to the second PLMN in a connected state. The cross-network connection state signaling contains real or hidden information related to the connected state service context of the UE in the first PLMN. Cross-network connection-state signaling is processed based on real or hidden information related to the connection-state service context of the UE in the first PLMN, so as to realize continuous connection-state communication between the UE in the first PLMN and the second PLMN. Real or hidden information related to the UE's connection-state service context in the first PLMN, specifically including: The first PLMN real topology information of the UE in the first PLMN connected-state service context, or the first PLMN hidden topology information obtained by topology hiding the first PLMN real topology information of the UE in the first PLMN connected-state service context.

2. The method according to claim 1, characterized in that, Real or hidden information related to the UE's connection-state service context in the first PLMN, specifically including: The UE is in the connected state service context of the first PLMN.

3. The method according to claim 2, characterized in that, Cross-network connection-state signaling is processed based on real or hidden information related to the UE's connection-state service context in the first PLMN, to achieve continuous connection-state communication between the UE and the second PLMN, specifically including: If the cross-network connection state signaling is the first cross-network connection state signaling, and the first cross-network connection state signaling contains the first PLMN real topology information of the UE in the connection state service context of the first PLMN, then topology hiding is performed on the first PLMN real topology information in the first cross-network connection state signaling to obtain the second cross-network connection state signaling containing the first PLMN hidden topology information, so that the second PLMN responds to the second cross-network connection state signaling.

4. The method according to claim 3, characterized in that, The first cross-network connection state signaling is generated for the UE by the first network function (NF) element of the first PLMN. The connection state service context of the UE in the first PLMN is the protocol data unit (PDU) session context of the UE in the first PLMN. The real topology information of the first PLMN is the real address of the second NF element of the first PLMN that is responsible for processing the PDU session of the first PLMN for the UE.

5. The method according to claim 4, characterized in that: The format of the real address of the second NF network element of the first PLMN is Internet Protocol IP address or Fully Qualified Domain Name (FQDN); The hidden topology information of the first PLMN is specifically the hidden address of the second NF network element of the first PLMN in FQDN format, which corresponds to the real address of the second NF network element of the first PLMN.

6. The method according to any one of claims 4-5, characterized in that, The method is applied to the first NF network element of the first PLMN; Topology hiding is performed on the first PLMN's true topology information in the first cross-network connection state signaling to obtain a second cross-network connection state signaling containing the first PLMN's hidden topology information, so that the second PLMN responds to the second cross-network connection state signaling, specifically including: The first cross-network connection state signaling is sent to the Security Edge Protection Agent (SEPP) network element of this network, so that the SEPP network element of this network performs topology hiding of the real address of the second NF network element of this network in the first cross-network connection state signaling, so as to obtain the second cross-network connection state signaling containing the hidden address of the second NF network element of this network, and sends the second cross-network connection state signaling to the second PLMN, so that the second PLMN responds to the second cross-network connection state signaling.

7. The method according to claim 6, characterized in that, Send the first cross-network connection state signaling to the Security Edge Protection Agent (SEPP) network element of this network, specifically including: The first cross-network connection state signaling is sent to the SEPP network element of this network through the first cross-network connection state signaling communication interface of this network. The first cross-network connection state signaling communication interface of this network is a pre-established interface through which the first NF network element of this network transfers the signaling to be sent to the NF network element of another network to the SEPP network element of this network.

8. The method according to claim 6, characterized in that, The first NF network element of this network is specifically the Mobility and Access Management Function (AMF) network element, and the second NF network element is specifically the Session Management Function (SMF) network element. The method specifically includes: If the AMF network element of this network receives a radio configuration handover request sent by the base station of this network for a UE that has moved from this network to another network in a connected state, then generates a first Create UE Context Request signaling to be sent to the second PLMN according to the radio configuration handover request. The first Create UE Context Request signaling contains the real address of the SMF network element of this network in the PDU session context of this network. The local AMF network element sends the first Create UE Context Request signaling to the local SEPP network element, so that the local SEPP network element performs topology hiding of the real address of the local SMF network element in the first Create UE Context Request signaling, thereby obtaining a second Create UE Context Request signaling containing the hidden address of the local SMF network element, and sends the second Create UE Context Request signaling to the second PLMN, so that the second PLMN responds to the second Create UE Context Request signaling.

9. The method according to claim 6, characterized in that, The first NF network element of this network is specifically the intermediate hI-SMF network element belonging to the hPLMN, and the second NF network element of this network is specifically the anchor point hA-SMF network element of the hPLMN. Alternatively, the first NF network element of this network is specifically the h-SMF network element of the hPLMN, and the second NF network element of this network is specifically the h-SMF network element of the hPLMN. The method specifically includes: If the UE moves from the hPLMN to the visited vPLMN in a connected state, and the hI-SMF network element / h-SMF network element receives a PDU session context request signaling sent by the vPLMN to the UE based on the second Create UE Context Request signaling from the hPLMN, then the hI-SMF network element / h-SMF network element generates a first type A PDU session context response signaling to be sent to the vPLMN based on the PDU session context request signaling. The first type A PDU session context response signaling contains the real address of the hA-SMF network element / h-SMF network element in the UE's PDU session context in this network. The hI-SMF network element / h-SMF network element sends the first Type A PDU session context response signaling to the local SEPP network element, so that the local SEPP network element performs topology hiding on the real address of the hI-SMF network element / h-SMF network element in the first Type A PDU session context response signaling to obtain the second Type A PDU session context response signaling containing the hidden address of the hI-SMF network element / h-SMF network element, and sends the second Type A PDU session context response signaling to the vPLMN, so that the vPLMN responds to the second Type A PDU session context response signaling.

10. The method according to claim 6, characterized in that, The first NF network element of this network is specifically the Mobility and Access Management Function (AMF) network element, and the second NF network element is specifically the Session Management Function (SMF) network element. The method specifically includes: If the AMF network element of this network receives a UE context creation request sent by the second PLMN for the UE, it generates a first UE context creation response signaling to be sent to the second PLMN according to the UE UE creation UE context request. The first UE context creation response signaling contains the real address of the SMF network element of this network in the PDU session context of this network. The local AMF network element sends the first Create UE Context Response signaling to the local SEPP network element, so that the local SEPP network element performs topology hiding on the real address of the local SMF network element in the first Create UE Context Response signaling, thereby obtaining the second Create UE Context Response signaling containing the hidden address of the local SMF network element, and sends the second Create UE Context Response signaling to the second PLMN, so that the second PLMN responds to the second Create UE Context Response signaling.

11. The method according to claim 6, characterized in that, The first NF network element of this network is specifically the intermediate hI-SMF network element belonging to the hPLMN, and the second NF network element of this network is specifically the anchor point hA-SMF network element of the hPLMN. Alternatively, the first NF network element of this network is specifically the h-SMF network element of the hPLMN, and the second NF network element of this network is specifically the h-SMF network element of the hPLMN. The method further includes: If the UE moves from the hPLMN to the visited vPLMN in a connected state, and the hI-SMF network element / h-SMF network element receives a PDU session context request signaling sent by the vPLMN to the UE based on the second Create UE Context Response signaling from the hPLMN, then the hI-SMF network element / h-SMF network element generates a first type A PDU session context response signaling to be sent to the vPLMN based on the PDU session context request signaling. The first type A PDU session context response signaling contains the real address of the hA-SMF network element / h-SMF network element in the UE's PDU session context in this network. The hI-SMF network element / h-SMF network element sends the first Type A PDU session context response signaling to the local SEPP network element, so that the local SEPP network element performs topology hiding on the real address of the hI-SMF network element / h-SMF network element in the first Type A PDU session context response signaling to obtain the second Type A PDU session context response signaling containing the hidden address of the hI-SMF network element / h-SMF network element, and sends the second Type A PDU session context response signaling to the vPLMN, so that the vPLMN responds to the second Type A PDU session context response signaling.

12. The method according to any one of claims 4-5, characterized in that, The method is applied to the local security edge protection agent (SEPP) network element of the first PLMN; Topology hiding is performed on the first PLMN's true topology information in the first cross-network connection state signaling to obtain a second cross-network connection state signaling containing the first PLMN's hidden topology information, so that the second PLMN responds to the second cross-network connection state signaling, specifically including: The real address of the second NF network element in this network is topologically hidden in the first cross-network connection state signaling from the first NF network element in this network, so as to obtain the second cross-network connection state signaling containing the hidden address of the second NF network element in this network, and the second cross-network connection state signaling is sent to the second PLMN so that the second PLMN responds to the second cross-network connection state signaling.

13. The method according to claim 12, characterized in that, The first cross-network connection state signaling is received from the first NF network element of this network through the first cross-network connection state signaling communication interface of this network. The first cross-network connection state signaling communication interface of this network is a pre-established interface through which the first NF network element of this network transfers the signaling to be sent to the NF network element of another network to the SEPP network element of this network.

14. The method according to claim 12, characterized in that: The first NF network element in this network is specifically the Mobility and Access Management Function (AMF) network element; the second NF network element in this network is specifically the Session Management Function (SMF) network element; and the first cross-network connection state signaling is specifically the first UE context creation request signaling or the first UE context creation response signaling; or... The first NF network element of this network is specifically the intermediate hI-SMF network element belonging to the hPLMN, and the second NF network element of this network is specifically the anchor hA-SMF network element of the hPLMN. Alternatively, the first NF network element of this network is specifically the h-SMF network element of the hPLMN, and the second NF network element of this network is specifically the h-SMF network element of the hPLMN. The first cross-network connection state signaling is specifically the first Class A PDU session context response signaling.

15. The method according to claim 12, characterized in that, Topology hiding is performed on the real address of the second NF network element in the first cross-network connection state signaling from the first NF network element of this network to obtain the second cross-network connection state signaling containing the hidden address of the second NF network element of this network, specifically including: For the first cross-network connection state signaling from the first NF network element of this network, extract the real address of the second NF network element of this network in the format of Internet Protocol IP address or Fully Qualified Domain Name (FQDN); The real address of the second NF network element in this network is topologically hidden based on the symmetric encryption algorithm, and the encryption result is converted into the hidden address of the second NF network element in this network in the format of FQDN. Replace the real address of the second NF network element in the first cross-network connection state signaling with the hidden address of the second NF network element in this network to obtain the second cross-network connection state signaling.

16. The method according to any one of claims 3-5, characterized in that, The method is applied to the first NF network element of the second PLMN; Topology hiding is performed on the first PLMN's true topology information in the first cross-network connection state signaling to obtain a second cross-network connection state signaling containing the first PLMN's hidden topology information, so that the second PLMN responds to the second cross-network connection state signaling, specifically including: According to the first cross-network connection state signaling request, the Security Edge Protection Agent (SEPP) network element of this network initiates a service discovery request to the first PLMN, so that the SEPP network element of this network receives the service discovery response sent by the first PLMN according to the service discovery request; The system receives the first PLMN hidden topology information in the service discovery response sent by the SEPP network element of this network, and replaces the first PLMN real topology information in the first cross-network connection state signaling with the first PLMN hidden topology information to obtain the second cross-network connection state signaling, and responds to the second cross-network connection state signaling in this network.

17. The method according to claim 16, characterized in that, According to the first cross-network connection state signaling request, the Security Edge Protection Agent (SEPP) network element of this network initiates a service discovery request to the first PLMN, specifically including: Determine whether the first cross-network connection state signaling comes from a different network. If so, determine whether the first cross-network connection state signaling contains the real address of the NF network element of the different network in the Internet Protocol IP format. If so, request the SEPP network element of this network to initiate a service discovery request to the first PLMN from which the first cross-network connection state signaling comes.

18. The method according to claim 2, characterized in that, The method is applied to the local network elements of the second PLMN; Cross-network connection-state signaling is processed based on real or hidden information related to the UE's connection-state service context in the first PLMN, to achieve continuous connection-state communication between the UE and the second PLMN, specifically including: If the cross-network connection state signaling is the second cross-network connection state signaling, and the second cross-network connection state signaling contains the first PLMN hidden topology information obtained by topology hiding the first PLMN real topology information in the connection state service context of the UE in the first PLMN, then the third cross-network connection state signaling is generated in response to the second cross-network connection state signaling. The third cross-network connection state signaling contains the first PLMN hidden topology information, and the third cross-network connection state signaling is sent to the first PLMN so that the first PLMN responds to the third cross-network connection state signaling.

19. The method according to claim 18, characterized in that, The second cross-network connection state signaling is specifically the second UE context creation request signaling or the second UE context creation response signaling; the third cross-network connection state signaling is specifically the PDU session context request; or... The second cross-network connection state signaling is specifically the second type A PDU session context response signaling, and the third cross-network connection state signaling is specifically the PDU session update request.

20. The method according to claim 18, characterized in that, The network elements of this network include the Security Edge Protection Proxy (SEPP) network element, the first network function (NF) network element, and / or the second NF network element. The method includes: The SEPP network element of this network receives the second cross-network connection state signaling from the first PLMN and forwards the second cross-network connection state signaling to the first NF network element of this network; The first NF network element of this network responds to the second cross-network connection state signaling to generate the first and third cross-network connection state signaling. The first and third cross-network connection state signaling contains the first PLMN hidden topology information taken from the second cross-network connection state signaling, and sends the first and third cross-network connection state signaling to the second NF network element or the SEPP network element of this network. If the first and third cross-network connection state signaling is sent to the second NF network element of this network, the second NF network element of this network generates the second and third cross-network connection state signaling based on the first and third cross-network connection state signaling. The second and third cross-network connection state signaling contains the first PLMN hidden topology information taken from the first and third cross-network connection state signaling, and sends the second and third cross-network connection state signaling to the SEPP network element of this network. The SEPP network element of this network performs topology hiding on the real topology information of this network that may be contained in the first or third cross-network connection state signaling or the second or third cross-network connection state signaling, so as to obtain the third cross-network connection state signaling and send the third cross-network connection state signaling to the first PLMN so that the first PLMN responds to the third cross-network connection state signaling.

21. The method according to claim 2, characterized in that, The method is applied to the local network elements of the first PLMN; Cross-network connection-state signaling is processed based on real or hidden information related to the UE's connection-state service context in the first PLMN, to achieve continuous connection-state communication between the UE and the second PLMN, specifically including: If the cross-network connection state signaling is a third cross-network connection state signaling from the second PLMN, and the third cross-network connection state signaling contains hidden topology information of the local network, which is obtained by the local network based on the real topology information of the local network in the connection state service context of the UE in the local network and sent to the second PLMN, then the hidden topology information of the local network in the third cross-network connection state signaling is used to perform topology restoration to obtain a fourth cross-network connection state signaling containing the real topology information of the local network, and the local network responds to the fourth cross-network connection state signaling.

22. The method according to claim 21, characterized in that, The third cross-network connection state signaling is the response of the second PLMN to the second cross-network connection state signaling from the first PLMN. The second cross-network connection state signaling is obtained by the local network security edge protection agent (SEPP) network element by topology hiding the local network real topology information in the first cross-network connection state signaling from the local network first network function (NF) network element. The first cross-network connection state signaling is generated by the local network first NF network element for the UE and contains the local network real topology information of the UE in the connection state service context of the local network. The UE's connection state service context in the local network is the UE's protocol data unit (PDU) session context in the local network. The local network real topology information is the real address of the local network second NF network element responsible for processing the local network PDU session for the UE.

23. The method according to claim 22, characterized in that, The network element in this network is specifically the SEPP network element of this network, and the method specifically includes: Receive third cross-network connection state signaling from the second PLMN; Replace the hidden address of the second NF network element in the third cross-network connection state signaling with the real address of the second NF network element in this network to obtain the fourth cross-network connection state signaling. The fourth cross-network connection state signaling is sent to the second NF network element of this network, so that the second NF network element of this network responds to the fourth cross-network connection state signaling.

24. The method according to claim 23, characterized in that, Sending the fourth cross-network connection state signaling to the second NF network element of this network, specifically including: The fourth cross-network connection state signaling is sent to the second NF network element of this network through the second cross-network connection state signaling communication interface of this network. The second cross-network connection state signaling communication interface of this network is a pre-established interface that forwards the signaling to be sent from the other network NF network element to the second NF network element of this network to the second NF network element of this network by the SEPP network element of this network.

25. The method according to claim 22, characterized in that, The first NF network element of this network is specifically the hAMF network element belonging to the hPLMN for mobility and access management functions, and the second NF network element of this network is specifically the hA-SMF network element belonging to the hPLMN for anchor session management functions. The method is applied to intermediate hI-SMF network elements belonging to hPLMN, and specifically includes: Receive third cross-network connection state signaling; The real address of the hA-SMF network element is obtained from the hAMF network element according to the third cross-network connection state signaling; Replace the hidden address of the hA-SMF network element in the third cross-network connection state signaling with the real address of the obtained hA-SMF network element to obtain the fourth cross-network connection state signaling; The fourth cross-network connection state signaling is sent to the hA-SMF network element so that the hA-SMF network element responds to the fourth cross-network connection state signaling.

26. The method according to claim 2, characterized in that, The first PLMN is the visiting vPLMN, and the second PLMN is the home hPLMN. The method is applied to the local network security edge protection agent hSEPP network element of the hPLMN. Cross-network connection-state signaling is processed based on real or hidden information related to the UE's connection-state service context in the first PLMN, to achieve continuous connection-state communication between the UE and the second PLMN, specifically including: If the cross-network connection state signaling is a Type B Protocol Data Unit (PDU) session context response signaling, and the Type B PDU session context response signaling contains the UE's PDU session context in the vPLMN and the hidden address of the local network function (hNF) element in the hPLMN, then topology restoration is performed on the hidden address of the hNF element in the Type B PDU session context response signaling to obtain a Type B PDU session context response signaling containing the real topology address of the hNF element. The Type B PDU session context response signaling is then sent to the hNF element so that the hNF element can obtain the UE's PDU session context in the vPLMN from the Type B PDU session context response signaling.

27. The method according to claim 2, characterized in that, The first PLMN is the visiting vPLMN, and the second PLMN is the home hPLMN. The method is applied to the hI-SMF network element of the hPLMN local network intermediate session management function. Cross-network connection-state signaling is processed based on real or hidden information related to the UE's connection-state service context in the first PLMN, to achieve continuous connection-state communication between the UE and the second PLMN, specifically including: If the cross-network connection state signaling is a Type B PDU session context response signaling, and the Type B PDU session context response signaling contains the UE's PDU session context in the vPLMN and the hidden address of the local anchor point hA-SMF network element in the hPLMN, then topology restoration is performed on the hidden address of the hA-SMF network element in the Type B PDU session context response signaling to obtain a Type B PDU session context response signaling containing the real topology address of the hA-SMF network element. The Type B PDU session context response signaling is then sent to the hA-SMF network element so that the hA-SMF network element obtains the UE's PDU session context in the vPLMN from the Type B PDU session context response signaling.

28. The method according to claim 27, characterized in that, Perform topology reconstruction on the hidden hA-SMF network element address in the first type B PDU session context response signaling to obtain the second type B PDU session context response signaling containing the real topology address of the hA-SMF network element, specifically including: The hA-SMF network element real address is obtained from the local mobility and access management function hAMF network element of hPLMN according to the first type B PDU session context response signaling; Replace the hidden address of the hA-SMF network element in the first type B PDU session context response signaling with the obtained real address of the hA-SMF network element to obtain the second type B PDU session context response signaling.

29. An inter-network communication device, characterized in that, include: The acquisition module is used to acquire cross-network connection state signaling of a user equipment (UE) moving from a first public land mobile network (PLMN) to a second PLMN in a connected state. The cross-network connection state signaling contains real or hidden information related to the connection state service context of the UE in the first PLMN. The processing module, connected to the acquisition module, is used to process cross-network connection state signaling based on real or hidden information related to the connection state service context of the UE in the first PLMN, so as to realize continuous connection state communication between the UE in the first PLMN and the second PLMN. Real or hidden information related to the UE's connection-state service context in the first PLMN, specifically including: The first PLMN real topology information of the UE in the first PLMN connected-state service context, or the first PLMN hidden topology information obtained by topology hiding the first PLMN real topology information of the UE in the first PLMN connected-state service context.

30. The apparatus according to claim 29, characterized in that, The device is specifically a local network function (NF) network element of the first PLMN or the local network security edge protection agent (SEPP) network element of the second PLMN, or the first PLMN or the second PLMN.

31. An electronic device, characterized in that, include: A memory that stores programs; A processor, when running a program stored in the memory, performs the inter-network communication method as described in any one of claims 1-28.

32. A computer-readable storage medium, characterized in that, It stores a computer program, which, when executed by a processor, implements the inter-network communication method as described in any one of claims 1-28.

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