Network switching method, converged network element, communication system and storage medium

Abstract

The embodiment of the application provides a network switching method, a fusion network element, a communication system and a storage medium, and belongs to the field of mobile communication. The method comprises the following steps: performing first PFCP session updating with a user plane fusion network element according to a session context request, so as to initiate a network switching process, and enabling a user equipment to switch between a 4G session and a 5G session, wherein the user plane fusion network element is a network element obtained by fusing a serving gateway user plane network element and an intermediate user plane network element in the core network. The technical scheme of the embodiment of the application can reduce the interaction process by performing PFCP session updating with the user plane fusion network element according to the session context request, thereby improving the efficiency of network switching and ensuring the continuity of sessions and services.

Description

Technical Field

[0001] This invention relates to the field of mobile communications, and more particularly to a network handover method, a converged network element, a communication system, and a storage medium. Background Technology

[0002] With the rapid development of 5G communication technology, more and more users are starting to use 5G networks. During use, when the 5G network signal cannot cover the user's device area, the user device will switch from the 5G network to the 4G network; and when the 5G network signal regains coverage, the user device will switch from the 4G network to the 5G network. Therefore, a 4G / 5G network handover solution is needed.

[0003] Existing 4G / 5G network handover solutions typically involve adding SGW-U (Serving Gateway User plane function), SGW-C (Serving Gateway Control plane function), and SMF (Session Management Function) + PGW-C (Packet Data Network Gateway Control plane function) to achieve network handover. During the handover process, since SMF + PGW-C is the converged anchor point and cannot be changed, it is necessary to insert SGW-C / SGW-U and remove I-SMF (Intermediate SMF) / I-UPF (Intermediate User Plane Function) to support session continuity. However, this network handover solution involves numerous network elements, resulting in a complex interaction process and significant changes in the user plane path, thus increasing handover latency. Furthermore, when I-UPF or SGW-U hosts traffic offloading services, network handover can lead to service interruption.

[0004] Therefore, improving the efficiency of network handover and ensuring the continuity of user sessions and services during network handover is an urgent problem to be solved. Summary of the Invention

[0005] The main objective of this invention is to provide a network handover method, a converged network element, a communication system, and a storage medium. By requesting and updating the PFCP session with the user plane converged network element based on the session context, the interaction process can be reduced, thereby improving the efficiency of network handover and ensuring the continuity of sessions and services.

[0006] In a first aspect, embodiments of the present invention provide a network handover method applied to control plane converged network elements, comprising:

[0007] Based on the session context request, a first PFCP session update is performed with the user plane converged network element to initiate a network handover process, enabling the user equipment to switch between 4G and 5G sessions. The user plane converged network element is a network element formed by merging the service gateway user plane network element and the intermediate user plane network element in the core network.

[0008] Secondly, embodiments of the present invention also provide a network handover method, applied to a user plane converged network element, comprising:

[0009] The system receives a PFCP session update request sent by a control plane converged network element, wherein the control plane converged network element is a network element formed by merging the serving gateway control plane network element and the intermediate session management network element in the core network; and performs a first PFCP session update with the control plane converged network element according to the PFCP session update request to initiate a network handover process, enabling the user equipment to switch between 4G and 5G sessions.

[0010] Thirdly, embodiments of the present invention also provide a converged network element, including a processor, a memory, a computer program stored in the memory and executable by the processor, and a data bus for implementing connection communication between the processor and the memory, wherein the computer program, when executed by the processor, implements the network switching method corresponding to the control plane converged network element as described above.

[0011] Fourthly, embodiments of the present invention also provide a converged network element, including a processor, a memory, a computer program stored in the memory and executable by the processor, and a data bus for implementing connection communication between the processor and the memory, wherein the computer program, when executed by the processor, implements the network handover method corresponding to the user plane converged network element as described above.

[0012] Fifthly, embodiments of the present invention also provide a communication system, the communication system comprising a control plane converged network element and a user plane converged network element. The control plane converged network element is a network element formed by merging the serving gateway control plane network element and the intermediate session management network element in the core network. The user plane converged network element is a network element formed by merging the serving gateway user plane network element and the intermediate user plane network element in the core network. The control plane converged network element is used to send a PFCP session update request to the user plane converged network element. The user plane converged network element is used to receive the PFCP session update request sent by the control plane converged network element, and perform a first PFCP session update with the control plane converged network element according to the PFCP session update request to initiate a network handover process, enabling the user equipment to switch between a 4G session and a 5G session.

[0013] In a sixth aspect, embodiments of the present invention also provide a storage medium for computer-readable storage, characterized in that the storage medium stores one or more programs, which can be executed by one or more processors to implement the steps of any network handover method provided in this specification.

[0014] This invention provides a network handover method, a converged network element, a communication system, and a storage medium. By performing a first PFCP session update with the user plane converged network element according to a session context request, a network handover process is initiated, enabling user equipment to switch between 4G and 5G sessions. Therefore, the interaction process can be reduced and service interruptions can be avoided, thereby improving the efficiency of network handover and ensuring the continuity of sessions and services.

[0015] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit the invention. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the structure of a communication system provided in an embodiment of the present invention;

[0018] Figure 2 This is a schematic interaction diagram of a control plane fusion network element and a user plane fusion network element provided in an embodiment of the present invention;

[0019] Figure 3This is a schematic block diagram of the structure of a control plane fusion network element provided in an embodiment of the present invention;

[0020] Figure 4 This is a schematic block diagram of the structure of a user plane fusion network element provided in an embodiment of the present invention;

[0021] Figure 5 This is a schematic flowchart of a network handover method provided in an embodiment of the present invention;

[0022] Figure 6 This is a schematic flowchart illustrating the sub-steps of switching a 5G session with I-SMF to a 4G session according to an embodiment of the present invention.

[0023] Figure 7 This is a schematic interaction diagram of a 5G session switching to 4G with I-SMF provided in an embodiment of the present invention;

[0024] Figure 8 This is a schematic flowchart illustrating a sub-step of establishing a first indirect forwarding tunnel between a 4G base station and a user plane converged network element, provided by an embodiment of the present invention.

[0025] Figure 9 This is a schematic flowchart illustrating the sub-steps of a user equipment switching from a 5G session to a 4G session when the user equipment is in an idle state and has I-SMF, according to an embodiment of the present invention.

[0026] Figure 10 This is a schematic interaction diagram provided by an embodiment of the present invention, showing the handover of a 5G session with I-SMF to a 4G session when the user equipment is in an idle state.

[0027] Figure 11 This is a schematic flowchart illustrating a sub-step of 4G session switching to 5G insertion of I-SMF provided in an embodiment of the present invention;

[0028] Figure 12 This is a schematic interactive diagram illustrating the insertion of I-SMF during 4G session switching to 5G, provided by an embodiment of the present invention.

[0029] Figure 13 This is a schematic flowchart illustrating a sub-step of establishing a second indirect forwarding tunnel between a 5G base station and a user plane converged network element, provided by an embodiment of the present invention.

[0030] Figure 14 This is a schematic flowchart of a sub-step for switching a 4G session to a 5G I-SMF session when there is no N26 tunnel between the AMF and the MME, provided by an embodiment of the present invention.

[0031] Figure 15This is a schematic interaction diagram provided by an embodiment of the present invention, showing the switching of a 4G session to 5G insertion into an I-SMF when there is no N26 tunnel between the AMF and the MME.

[0032] Figure 16 This is a schematic flowchart of another network switching method provided in an embodiment of the present invention. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] The flowchart shown in the attached diagram is for illustrative purposes only and does not necessarily include all content and operations / steps, nor does it necessarily have to be performed in the order described. For example, some operations / steps can be broken down, combined, or partially merged, so the actual execution order may change depending on the actual situation.

[0035] It should be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0036] Please see Figure 1 , Figure 1 This is a schematic diagram of the structure of a communication system provided in an embodiment of the present invention. Figure 1 As shown, the communication system includes control plane converged network elements and user plane converged network elements.

[0037] It should be noted that the control plane converged network element is the network element formed by merging the Serving Gateway Control plane function (SGW-C) and the Intermediate Session Management Function (I-SMF) in the core network; the user plane converged network element is the network element formed by merging the Serving Gateway User plane function (SGW-U) and the Intermediate User Plane Function (I-UPF) in the core network. By merging the Serving Gateway Control plane function and the Intermediate Session Management Function, the resource consumption of the control plane can be reduced, thereby allowing more users to access the network; by merging the Serving Gateway User plane function and the Intermediate User Plane Function, the 4G base station can support local traffic offloading services, minimizing the traffic impact on the bearer network during service handover.

[0038] The control plane converged network element is used to send PFCP (Packet Forwarding Control Protocol) session update requests to the user plane converged network element. The user plane converged network element is used to receive the PFCP session update requests sent by the control plane converged network element, and perform the first PFCP session update with the control plane converged network element according to the PFCP session update requests to initiate the network handover process, enabling the user equipment to switch between 4G and 5G sessions.

[0039] It should be noted that, in the embodiments of the present invention, by extending the protocol interface and adding protocol procedures, the service gateway control plane network element and the intermediate session management network element in the core network can be integrated, as well as the service gateway user plane network element and the intermediate user plane network element in the core network can be integrated.

[0040] For example, when an SMF (Session Management Function) registers for service with an NRF (Network Repository Function) or an MME (Mobility Management Entity) registers with an HSS (Home Subscriber Server), it can carry the node name of the SGW (Serving Gateway) so that the AMF (Access and Mobility Management Function) can determine the I-SMF in the control plane converged network element based on the node name of the SGW.

[0041] For example, an N26 tunnel can be added between the AMF and the MME, enabling the AMF to communicate and interact with the MME, thereby ensuring that the AMF and the MME can select control plane converged network elements and communicate and interact.

[0042] It should be noted that in existing technologies, since SGW-C and SGW-U communicate via the Sxa tunnel, and I-SMF and I-UPF communicate via the N4 tunnel, service continuity is supported during network handover by inserting SGW-C / SGW-U and deleting I-SMF / I-UPF. In this embodiment of the invention, since both Sxa and N4 tunnels use the PFCP protocol, by using control plane converged network elements and user plane converged network elements, the PFCP session can remain unchanged during network handover without establishing multiple PFCP sessions, thereby reducing performance loss to the UPF.

[0043] Please see Figure 2 , Figure 2 This is a schematic interaction diagram of the control plane fusion network element and the user plane fusion network element provided in an embodiment of the present invention. For example... Figure 2 As shown, the Access Management Network Element (AMF) can communicate with the User Equipment (UE) through the N1 tunnel, with the 5G base station through the N2 tunnel, with the MME through the N26 tunnel, with the I-SMF in the control plane converged network element through the N11 tunnel, and with the HSS+UDM through the N8 tunnel. The UDM (Unified Data Management) is a network element integrated into the Home Subscriber Server (HSS).

[0044] For example, the Mobility Management Element (MME) can communicate with 4G base stations through the S1-MME tunnel and with the SGW-C in the control plane converged network element through the S11 tunnel. The 5G base station communicates with the I-UPF in the user plane converged network element through the N3 tunnel, and the 4G base station communicates with the SGW-U in the user plane converged network element through the S1-U tunnel.

[0045] exist Figure 2 In this context, the first gateway converged network element (PGW-C+SMF) is a network element that merges the Packet Data Network Gateway Control Network Element (PGW-C) and the Session Management Network Element (SMF) in the core network; the second gateway converged network element (PGW-U+UPF) is a network element that merges the Packet Data Network Gateway User Plane Network Element (PGW-U) and the User Plane Network Element (UPF) in the core network.

[0046] For example, the first gateway converged network element can communicate with the control plane converged network element through the N16a or S5-C tunnel, or with the HSS+UDM through the N10 tunnel, or with the PCRF+PCF through the N7 tunnel. Here, PCRF+PCF refers to the converged Policy and Charging Rule Function and Policy Control Function.

[0047] For example, the second gateway converged network element can communicate and interact with the user plane converged network element through the N9 or S5-U tunnel, and can also communicate and interact with the data network (DN) through the N6 tunnel.

[0048] exist Figure 2 In the context of network architecture, the user plane forwarding path can be: User Equipment (UE) -> 5G base station -> User plane converged network element -> Second gateway converged network element -> Data Network (DN), or it can be: User Equipment (UE) -> 4G base station -> User plane converged network element -> Second gateway converged network element -> Data Network (DN). The control plane forwarding path can be: User Equipment (UE) -> Mobility Management Element (MME) -> Control Plane Converged Network Element, or it can be: User Equipment (UE) -> Access Management Element (AMF) -> Control Plane Converged Network Element.

[0049] Please see Figure 3 , Figure 3 This is a schematic block diagram of the control plane fusion network element provided in an embodiment of the present invention. For example... Figure 3As shown, the control plane fusion network element 10 may include a processor 11 and a memory 12, wherein the processor 11 and the memory 12 can be connected by a bus, such as an I2C (Inter-integrated Circuit) bus or any applicable bus.

[0050] The memory 12 may include a non-volatile storage medium and internal memory. The non-volatile storage medium may store an operating system and a computer program. The computer program includes program instructions that, when executed, cause the processor 11 to perform a network handover method corresponding to the control plane fused network element.

[0051] The processor 11 provides computing and control capabilities to support the operation of the entire control plane fused network element 10.

[0052] In one embodiment, the processor 11 is configured to run a computer program stored in the memory 12, and to perform the following steps when executing the computer program:

[0053] Based on the session context request, a first PFCP session update is performed with the user plane converged network element to initiate a network handover process, enabling the user equipment to switch between 4G and 5G sessions. The user plane converged network element is a network element formed by merging the service gateway user plane network element and the intermediate user plane network element in the core network.

[0054] Processor 11 can be a Central Processing Unit (CPU), but it can also be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor can be a microprocessor or any conventional processor.

[0055] Please see Figure 4 , Figure 4 This is a schematic block diagram of the user plane fusion network element provided in an embodiment of the present invention. Figure 4 As shown, the user plane converged network element 20 may include a processor 21 and a memory 22, wherein the processor 21 and the memory 22 can be connected by a bus, such as an I2C (Inter-integrated Circuit) bus or any applicable bus.

[0056] The memory 22 may include a non-volatile storage medium and internal memory. The non-volatile storage medium may store an operating system and a computer program. The computer program includes program instructions that, when executed, cause the processor 21 to perform a network handover method corresponding to the user plane converged network element.

[0057] The processor 21 provides computing and control capabilities to support the operation of the entire user plane converged network element 20.

[0058] In one embodiment, the processor 21 is configured to run a computer program stored in the memory 22, and to perform the following steps when executing the computer program:

[0059] The system receives a PFCP session update request sent by a control plane converged network element, wherein the control plane converged network element is a network element formed by merging the serving gateway control plane network element and the intermediate session management network element in the core network; and performs a first PFCP session update with the control plane converged network element according to the PFCP session update request to initiate a network handover process, enabling the user equipment to switch between 4G and 5G sessions.

[0060] The processor 21 can be a Central Processing Unit (CPU), but it can also be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or any conventional processor.

[0061] The following detailed description of some embodiments of the present invention is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0062] Please see Figure 5 , Figure 5 This is a schematic flowchart illustrating a network handover method provided in an embodiment of the present invention. This network handover method can be applied to control plane converged network elements. By requesting PFCP session updates with user plane converged network elements based on the session context, it can reduce interaction processes, thereby improving network handover efficiency and ensuring session and service continuity. The network handover method includes step S10.

[0063] Step S10: Based on the session context request, perform the first PFCP session update with the user plane converged network element to initiate the network handover process, enabling the user equipment to switch between 4G and 5G sessions. The user plane converged network element is a network element formed by merging the service gateway user plane network element and the intermediate user plane network element in the core network.

[0064] For example, session context requests include two types: get session context requests and create session context requests. The get session context request is used to obtain the context of a 5G session in order to switch the 5G session to a 4G session; the create session context request is used to create the context of a 5G session in order to switch the 4G session to a 5G session.

[0065] Understandably, when switching a user equipment (UE) from a 5G session to a 4G session, the context of the 5G session needs to be obtained first. Tunnel information is then parsed from the context, and the MME (Mobile Equipment Management) uses this tunnel information to control the establishment of service tunnels and indirect forwarding tunnels between the 4G base station and the user plane converged network elements, thereby enabling the UE to switch from a 5G session to a 4G session. Conversely, when switching a UE from a 4G session to a 5G session, the context of the 5G session needs to be created first. The AMF (Active Software Frame) uses the tunnel information in the context to control the establishment of service tunnels and indirect forwarding tunnels between the 5G base station and the user plane converged network elements, thereby enabling the UE to switch from a 4G session to a 5G session.

[0066] Indirect forwarding tunnels refer to temporary tunnels created to ensure uninterrupted service during handover when direct transmission tunnels are not supported between 4G and 5G base stations. These temporary tunnels are dismantled after the session handover is completed.

[0067] For example, based on the session context request, a first PFCP session update is performed with the user plane converged network element to initiate a network handover process. The network handover process can be determined based on the type of session context request and the actual application scenario.

[0068] By performing the first PFCP session update with the user plane converged network element according to the session context request, a network handover process can be initiated, enabling user equipment to switch between 4G and 5G sessions. This simplifies the 4G / 5G interoperability handover process and reduces the load on the existing network service network element (SGW).

[0069] In this embodiment of the invention, the network handover method can be applied to a variety of application scenarios; for example, the application scenarios may include, but are not limited to: a scenario where a 5G session with I-SMF is switched to a 4G session; a scenario where a 4G session is switched to a 5G session with I-SMF; a scenario where a user equipment is in an idle state and a 5G session with I-SMF is switched to a 4G session; and a scenario where a 4G session is switched to a 5G session with I-SMF when there is no N26 tunnel between the AMF and the MME.

[0070] It should be noted that inserting an I-SMF means adding an I-SMF to the control plane network element of the service gateway in the core network, thus obtaining the control plane converged network element described in this embodiment of the invention; idle state means that the user equipment is in a state of not being connected to the network.

[0071] The following detailed description of some application scenarios of the present invention is provided in conjunction with the accompanying drawings.

[0072] Please see Figure 6 , Figure 6 This is an illustrative flowchart of a sub-step for switching a 5G session with I-SMF to a 4G session, provided by an embodiment of the present invention. Specifically, it may include the following steps S201 to S204.

[0073] Step S201: When the session context request is a session context request, a session context request response is sent to the access management network element in the core network, so that the access management network element sends a relocation request to the mobility management network element in the core network according to the session context request response.

[0074] Please see Figure 7 , Figure 7 This is a schematic interaction diagram illustrating a 5G session handover to 4G with I-SMF, provided by an embodiment of the present invention. Figure 7 In this context, Combo UPF represents a user plane converged network element, and Combo SMF represents a control plane converged network element.

[0075] It should be noted that, in this embodiment of the invention, the User Equipment (UE) has already established a PDU (Protocol Data Unit) session in the 5G radio access network. When the 5G base station needs to switch the UE's 5G session to a 4G session, the 5G base station sends a HANDOVER REQUIRED message to the Access Management Element (AMF) to notify the AMF that a UE needs to perform a session handover. The AMF then sends a request to obtain the session context to the control plane convergence element as needed.

[0076] In some embodiments, after receiving an Acquire Session Context request from the Access Management Element (AMF), the control plane converged network element sends an Acquire Session Context response to the access management network element in the core network, so that the access management network element sends a relocation request to the mobility management network element in the core network based on the Acquire Session Context response.

[0077] For example, if I-SMF supports SGW-C, I-SMF returns the node name of SGW-C in the Session Context Receiver response; if I-UPF supports SGW-U, it will also return the address of the S1-U tunnel of SGW-U.

[0078] It is understandable that, since the control plane converged network elements include I-SMF and SGW-C, and the user plane converged network elements include I-UPF and SGW-U, the session context response carries the node name of SGW-C and the address of the S1-U tunnel of SGW-U.

[0079] For example, the Access Management Element (AMF) sends a Forward Relocation Request to the Mobility Management Element (MME) based on the Acquire Session Context response. Specifically, based on the N26 tunnel, the AMF sends the PDN (Packet Data Network) connection context, security context, and MM (Mobility Management) context to the MME via the relocation request.

[0080] The PDN connection context can contain SGW information. The MM context refers to a set of information stored in the MS (Mobile Station) and SGSN (Serving SPRS Support Node), including user identification, status information, location information, and terminal capabilities, etc.

[0081] Step S202: Receive the session creation request sent by the mobility management network element according to the relocation request, and perform the first PFCP session update with the user plane convergence network element according to the session creation request.

[0082] In this embodiment of the invention, after receiving a relocation request, the Mobility Management Element (MME) can determine the Control Plane Convergence Element based on the SGW information contained in the PDN connection context in the relocation request, such as the node name of the SGW-C; and then send a Session Creation Request to the Control Plane Convergence Element to notify it to establish a bearer.

[0083] In some embodiments, the control plane converged network element receives a session creation request sent by the mobility management network element based on a relocation request, and performs a first PFCP session update with the user plane converged network element based on the session creation request.

[0084] For example, the control plane converged network element performs a first PFCP session update with the intermediate user plane network element in the user plane converged network element according to the session creation request, so as to obtain the first tunnel information between the user plane converged network element and the 5G base station.

[0085] By updating the first PFCP session with the user plane converged network element based on the session creation request, the PFCP session can remain unchanged during network handover without establishing multiple PFCP sessions, thereby reducing the performance loss to UPF.

[0086] It should be noted that, in this embodiment of the invention, the specific process of initiating a network handover procedure to enable the user equipment to switch between a 4G session and a 5G session includes steps S203 and S204.

[0087] Step S203: After performing the first PFCP session update with the user plane converged network element, obtain the first tunnel information between the user plane converged network element and the 5G base station.

[0088] It is understandable that after the first PFCP session update with the user plane converged network element, the first tunnel information between the user plane converged network element and the 5G base station can be obtained.

[0089] For example, the first tunnel information can be the tunnel information corresponding to tunnel N3.

[0090] Step S204: Based on the first tunnel information, establish a first service tunnel and a first indirect forwarding tunnel between the 4G base station and the user plane converged network element, so that the access management network element can switch the user equipment from a 5G session to a 4G session based on the established first service tunnel and the first indirect forwarding tunnel.

[0091] For example, the first service tunnel may include an S1-U tunnel; the first indirect forwarding tunnel is a newly built temporary tunnel that will be dismantled after the session handover is completed.

[0092] It should be noted that since the first tunnel information is the tunnel information corresponding to the N3 tunnel between the user plane converged network element and the 5G base station, the first service tunnel and the first indirect forwarding tunnel between the 4G base station and the user plane converged network element can be established based on the tunnel information corresponding to the N3 tunnel.

[0093] By establishing a service tunnel and a first indirect forwarding tunnel between the 4G base station and the user plane converged network element based on the first tunnel information, subsequent uplink and downlink data can be transmitted through the service tunnel, reducing the data transfer process.

[0094] Please see Figure 8 , Figure 8 This is a schematic flowchart of the sub-step in step S204, which establishes the first service tunnel and the first indirect forwarding tunnel between the 4G base station and the user plane converged network element based on the first tunnel information. Specifically, it may include the following steps S2041 to S2047.

[0095] Step S2041: Send a session creation response containing the first tunnel information to the mobility management network element, so that the mobility management network element sends a handover request to the 4G base station based on the first tunnel information.

[0096] In this embodiment of the invention, after obtaining the first tunnel information between the user plane converged network element and the 5G base station, the first tunnel information can be sent to the mobility management network element so that the mobility management network element can send a handover request to the 4G base station based on the first tunnel information, requesting the 4G base station to establish wireless network resources.

[0097] For example, wireless network resources may include, but are not limited to, carrying information and security context.

[0098] Step S2042: Receive the request to create an indirect data forwarding tunnel sent by the mobility management network element, wherein the request to create an indirect data forwarding tunnel is generated by the mobility management network element based on the handover response returned by the 4G base station based on the handover request.

[0099] For example, after receiving a handover request from the Mobility Management Network (MME), the 4G base station sends a HANDOVERREQUESTACKNOWLEDGE message to the MME. This handover response message indicates that the 4G base station is ready to receive GTP (GPRS Tunnelling Protocol) packet data units on the established E-RAB (Evolved Radio Access Bearer).

[0100] E-RAB refers to the user plane bearer, used for transmitting voice, data, and multimedia services between the user equipment (UE) and the core network (CN).

[0101] In some embodiments, if the Indirect Forwarding data forwarding method is adopted, the Mobility Management Element (MME) sends a Create Indirect Data Forwarding Tunnel Request to the Control Plane Convergence Element.

[0102] It should be noted that indirect forwarding refers to the process during handover where, if the 5G base station is unable to send downlink data to the user equipment (UE), the data is forwarded to the 4G base station via the core network element and then sent to the UE.

[0103] For example, the request to create an indirect data forwarding tunnel includes the address of the forwarding channel of the 4G base station and the TEID (Tunnel Endpoint ID).

[0104] Step S2043: Send a PFCP session update request to the user plane converged network element according to the request to create an indirect data forwarding tunnel, so as to request the establishment of the first service tunnel and the first indirect forwarding tunnel.

[0105] It should be noted that when the user plane converged network element performs PFCP session update with the control plane converged network element, it can generate the address information corresponding to the first service tunnel and the first indirect forwarding tunnel based on the address and TEID of the forwarding channel of the 4G base station.

[0106] Step S2044: Receive the PFCP session update response returned by the user plane converged network element according to the PFCP session update request, wherein the PFCP session update response includes the address information corresponding to the first service tunnel and the first indirect forwarding tunnel.

[0107] For example, the user plane converged network element can return the address information corresponding to the first service tunnel and the first indirect forwarding tunnel to the control plane converged network element through the PFCP Session Modification Response.

[0108] Step S2045: Based on the PFCP session update response, send a Create Indirect Data Forwarding Tunnel Response to the Mobility Management Network Element, so that the Mobility Management Network Element sends a Relocation Response to the Access Management Network Element based on the Create Indirect Data Forwarding Tunnel Response, wherein the Relocation Response includes the address information and tunnel endpoint identifier corresponding to the first indirect forwarding tunnel of the first service tunnel.

[0109] For example, a control plane converged network element can send a Create Indirect Data Forwarding Tunnel Response to a Mobility Management Element (MME) based on the PFCP session update response; the MME can then send a relocation response to an Access Management Element (AMF) based on the Create Indirect Data Forwarding Tunnel Response. For indirect forwarding data forwarding, the relocation response includes the address information and tunnel endpoint identifier corresponding to the first service tunnel and the first indirect forwarding tunnel.

[0110] Step S2046: Receive the update session context request sent by the access management network element according to the relocation response, wherein the update session context request includes the address information and the tunnel endpoint identifier corresponding to the first service tunnel and the first indirect forwarding tunnel.

[0111] For example, after receiving a relocation response from a mobility management element (MME), the access management element (AMF) can generate an update session context request that includes address information and tunnel endpoint identifiers corresponding to the first service tunnel and the first indirect forwarding tunnel.

[0112] It is understandable that the address information and tunnel endpoint identifiers corresponding to the first service tunnel and the first indirect forwarding tunnel are used by the control plane converged network element and the user plane converged network element to establish the first service tunnel and the first indirect forwarding tunnel.

[0113] Step S2047: Establish the first indirect forwarding tunnel with the address information, the tunnel endpoint identifier, and the user plane converged network element, and return an update session context response to the access management network element. The update session context response is used to indicate that the establishment of the first service tunnel and the first indirect forwarding tunnel has been completed.

[0114] For example, after establishing the first service tunnel and the first indirect forwarding tunnel with the user plane converged network element, the control plane converged network element returns an Nsmf_PDUSession_UpdateSMContext Response to the access management network element (AMF). The access management network element (AMF) then sends a HANDOVER COMMAND to the 5G base station to notify the 5G base station to complete the handover preparation.

[0115] In this embodiment of the invention, the 5G base station sends a handover command to the User Equipment (UE), notifying the UE to switch to the target access network. The target access network refers to the 4G radio access network. At this time, downlink data can be transmitted from the 5G base station to the 4G base station through the second gateway converged network element and the user plane converged network element. After the UE successfully switches to the target cell, uplink and downlink data are transmitted through the 4G base station.

[0116] For example, after the User Equipment (UE) successfully synchronizes with the target cell, it sends a Handover Confirm message to the 4G base station. At this time, the 4G base station sends the cached downlink data to the UE, while the uplink data is routed from the UE to the 4G base station, then to the user plane converged network element, and finally to the second gateway converged network element. The 4G base station sends a Handover Notification message to the Mobility Management Element (MME) to notify the MME that the UE is now located in the target cell.

[0117] For example, after receiving a handover notification message, the Mobility Management Element (MME) can send a Forward Relocation Complete Notification message to the Access Management Element (AMF), so that the AMF can return a Forward Relocation Complete Acknowledge message based on the relocation complete notification.

[0118] In some embodiments, after establishing the first service tunnel and the first indirect forwarding tunnel between the 4G base station and the user plane converged network element based on the first tunnel information, the method may further include: when receiving a release session context request sent by the access management network element, returning a release session context response to the access management network element, wherein the release session context request is used to indicate that the user equipment has completed the session handover.

[0119] For example, a Release Session Context request is used to request the deletion of the intermediate session management element (I-SMF), carrying an indication to delete only the I-SMF. The control plane converged network element switches its local context state to 4G and returns a Release Session Context response. This Release Session Context response indicates that the I-SMF deletion is complete.

[0120] In some embodiments, after establishing the first service tunnel and the first indirect forwarding tunnel between the 4G base station and the user plane converged network element based on the first tunnel information, the method may further include: when receiving an update bearer request sent by the mobility management network element, sending the update bearer request to the first gateway converged network element so that the first gateway converged network element and the second gateway converged network element perform a second PFCP session update to update the user plane forwarding path; receiving the update bearer response returned by the first gateway converged network element and sending the update bearer response to the mobility management network element so that the user equipment initiates a tracking area update procedure to the mobility management network element.

[0121] The update bearer request may include the user plane address and tunnel endpoint identifier (TEID) of the 4G base station.

[0122] In this embodiment of the invention, the mobility management network element can send an update bearer request to the control plane converged network element, so that the control plane converged network element sends the update bearer request to the first gateway converged network element. The first gateway converged network element can then perform a second PFCP session update with the second network element converged network element based on the update bearer request.

[0123] For example, the first gateway converged network element can perform a second PFCP session update with the second network element converged network element based on the user plane address and tunnel endpoint identifier (TEID) of the 4G base station in the update bearer request. This allows the user plane forwarding path to be updated.

[0124] For example, the original user plane forwarding path was: User Equipment (UE) -> 5G base station -> User plane converged network element -> Second gateway converged network element -> Data Network (DN); the updated user plane forwarding path is: User Equipment (UE) -> 4G base station -> User plane converged network element -> Second gateway converged network element -> Data Network (DN).

[0125] By updating the forwarding path on the user plane, the changes in the forwarding path are minimized, effectively reducing network handover latency and thus improving network handover efficiency.

[0126] In some embodiments, after completing the second PFCP session update, the first gateway converged network element can send a ModifyBearerResponse to the control plane converged network element. At this point, downlink data packets can be forwarded to the 4G base station via the user plane converged network element based on the newly established downlink data transmission channel. Thus, the end-to-end default bearer and dedicated bearer user plane data transmission channels between the user equipment (UE) and the second gateway converged network element are established.

[0127] In other embodiments, after receiving the update bearer response, the control plane convergence element can also send the update bearer response to the mobility management element (MME), so that the MME can forward the update bearer response to the user equipment (UE). The UE can then initiate a TAU (Trace Area Update) procedure to the MME based on the update bearer response.

[0128] In this embodiment of the invention, after establishing the first indirect forwarding tunnel between the 4G base station and the user plane converged network element, a timer can be set for periodically deleting the first indirect forwarding tunnel. The duration of the timer can be set according to actual conditions, and the specific value is not limited here. For example, when the timer expires, the access management network element (AMF) or the mobility management network element (MME) sends an indirect forwarding tunnel deletion request to the control plane converged network element; the control plane converged network element performs a PFCP session update with the user plane converged network element based on the indirect forwarding tunnel deletion request to delete the first indirect forwarding tunnel.

[0129] After the user plane forwarding path is switched over, the first gateway converged network element can also map some data streams mapped to the default bearer to dedicated bearers, so that the first network element converged network element can establish dedicated bearers.

[0130] In this embodiment of the invention, when a user does not roam across regions, the access management network element (AMF) does not need to be inserted into the intermediate session management network element (I-SMF). That is, the control plane fusion network element can also be fused with the first network element fusion network element, thereby further reducing connection latency.

[0131] By establishing the first service tunnel and the first indirect forwarding tunnel between the 4G base station and the user plane converged network element, it is possible to switch user equipment from 5G session to 4G session. This can reduce interaction processes and avoid service interruptions, thereby improving the efficiency of network handover and ensuring the continuity of sessions and services.

[0132] Please see Figure 9 , Figure 9 This is an illustrative flowchart of a sub-step for a user equipment in an idle state to switch from a 5G session to a 4G session with I-SMF, provided by an embodiment of the present invention. Specifically, it may include the following steps S301 to S304.

[0133] Step S301: When the session context request is a request to obtain session context, a request to obtain session context response is sent to the access management network element in the core network, so that the access management network element sends a context response to the mobility management network element in the core network according to the request to obtain session context response, wherein the request to obtain session context is generated by the access management network element according to the context request sent by the mobility management network element.

[0134] Please see Figure 10 , Figure 10 This is a schematic interaction diagram illustrating the handover of a 5G session to a 4G session by a user equipment (UE) in an idle state with I-SMF, according to an embodiment of the present invention. It should be noted that the TAU procedure is triggered when the UE moves from a 5G network coverage area to a 4G network coverage area.

[0135] In some embodiments, the user equipment (UE) sends a TAU request to the 4G base station so that the 4G base station forwards the TAU request to the mobility management element (MME).

[0136] For example, a TAU request may carry information about the current registration status of a user equipment (UE), such as the UE's registration status with a 5G base station.

[0137] For example, after receiving a TAU request sent by a 4G base station, the Mobility Management Element (MME) determines whether the TAU request was allocated by itself. If it is determined that the TAU request was not allocated by itself, it sends a context request to the Access Management Element (AMF) so that the AMF sends an Nsmf_PDUSession_Retrieve SM ContextRequest to the Control Plane Convergence Element.

[0138] For example, the control plane converged network element returns a session context acquisition response to the access management network element (AMF) based on the session context acquisition request. This session context acquisition response may include, but is not limited to, the PGW-C tunnel information of the PDN connection corresponding to the PDU session, the EBI (EPS bearer identity) carried by each 4G base station, the PGW-U tunnel information carried by each 4G base station, and the QoS (Quality of Service) parameters carried by each 4G base station.

[0139] In this embodiment of the invention, the Access Management Element (AMF) can send a context response to the Mobility Management Element (MME) based on the Acquire Session Context Response. The context response includes the mapped security context, default bearer, and dedicated bearer, etc.

[0140] In some embodiments, after receiving the context response, the Mobility Management Element (MME) can also determine whether to perform an authentication process based on local policies. This authentication process is the same as the MME's authentication process in the TAU (Tracking Area Access) procedure. The specific authentication process is not limited here. For example, after completing the authentication process, the MME can also send a Context Acknowledge message to the Access Management Element (AMF); this message includes a Cause value and an SGW Change Indication.

[0141] Step S302: Receive the session creation request sent by the mobility management network element according to the context response, and perform the first PFCP session update with the user plane convergence network element according to the session creation request.

[0142] For example, the Mobility Management Element (MME) can determine the SGW-C in the Control Plane Convergence Element based on the node information corresponding to the SGW-C of the PDN connection in the context response, and send a session creation request to the SGW-C.

[0143] In some embodiments, the control plane converged network element can determine whether the I-UPF in the user plane converged network element can continue to be used as SGW-U based on the TAI (Tracking Area Identity) and DNN (Data Network Name). When it is determined that the I-UPF can continue to be used as SGW-U, a PFCP session update request is sent to the user plane converged network element. The PFCP session update request may include the uplink and downlink PDRs (Packet Detection Rules) established by each 4G base station bearer of the PDN connection. During the first PFCP session update, the interface F-TEID (Full QualifiedTEID) of the S1-U tunnel and the interface F-TEID of the S5 / S8-U tunnel of the SGW-U can be allocated to the user plane converged network element. The interface F-TEID of the S1-U tunnel is used for forwarding uplink data; the interface F-TEID of the S5 / S8-U tunnel is used for forwarding downlink data.

[0144] It should be noted that, in this embodiment of the invention, the specific process of initiating a network switching procedure to enable the user equipment to switch between a 4G session and a 5G session includes steps S303 and S304.

[0145] Step S303: After performing the first PFCP session update with the user plane converged network element, send an update bearer request to the first gateway converged network element so that the first gateway converged network element and the second gateway converged network element perform a third PFCP session update to update the user plane forwarding path. The first gateway converged network element is a network element that merges the packet data network gateway control network element and the session management network element in the core network, and the second gateway converged network element is a network element that merges the packet data network gateway user plane network element and the user plane network element in the core network.

[0146] For example, the control plane converged network element sends an update bearer request to the first gateway converged network element, enabling the first gateway converged network element to obtain the interface F-TEID of the S5 / S8-U tunnel of SGW-C and the interface F-TEID of the S5 / S8-U tunnel of SGW-U. When the first gateway converged network element performs a third PFCP session update with the second gateway converged network element, it can notify the second network element to switch the downlink data tunnel to SGW-U. This allows the user plane forwarding path to be updated.

[0147] For example, the updated user plane forwarding path is: User Equipment (UE) -> 4G base station -> User plane converged network element -> Second gateway converged network element -> Data Network (DN).

[0148] Step S304: When the update bearer response returned by the first gateway converged network element is received, a session creation response is sent to the mobility management network element so that the mobility management network element can perform a location update with the home user server according to the session creation response, so that the user equipment can switch from a 5G session to a 4G session. The home user server includes the converged unified data management network element.

[0149] However, it should be noted that after the first network element converged network element completes the third PFCP session update with the second gateway converged network element, it can return an update bearer response to the control plane converged network element; wherein, the update bearer response contains the interface F-TEID of the S1-U tunnel of the SGW-U.

[0150] In some embodiments, the control plane converged network element can send a session creation response to the mobility management network element (MME) based on the update bearer response. The session creation response includes the interface F-TEID of the SGW-U's S1-U tunnel.

[0151] For example, the Mobility Management Element (MME) can send an Update Location Request to the UDM+HSS based on the Session Creation Response, causing the UDM+HSS to switch the User Equipment (UE) from a 5G session to a 4G session. The UDM+HSS can send a Deregistration Notification to the Access Management Element (AMF), causing the AMF to delete the session context based on the Deregistration Notification and send an Unsubscribe Message to the UDM+HSS to cancel the subscription to the UE's subscribed data.

[0152] In some embodiments, when the control plane converged network element receives a release session context request sent by the access management network element (AMF), it returns a release session context response to the AMF, wherein the release session context request is used to indicate that the user equipment (UE) has completed a session handover.

[0153] For example, a Release Session Context request is used to request the deletion of the intermediate session management element (I-SMF), carrying an indication to delete only the I-SMF. The control plane converged network element switches its local context state to 4G and returns a Release Session Context response. This Release Session Context response indicates that the I-SMF deletion is complete.

[0154] In some embodiments, after receiving the unsubscribe message, the UDM+HSS can also send an update location response to the Mobility Management Element (MME), so that the MME can send a TAU acceptance message to the User Equipment (UE) based on the update location response. The UE can then return a TAU completion message to the MME.

[0155] In this embodiment of the invention, the specific process of switching from a 4G session with I-SMF to a 5G session with I-SMF in an idle state is similar to the process of switching from a 5G session with I-SMF to a 4G session in an idle state. For details, please refer to the above embodiments. The specific details will not be repeated here.

[0156] By communicating and interacting with access management network elements and mobility management network elements, and by performing the first PFCP session update with user plane converged network elements, idle user equipment can switch from 5G session to 4G session, reducing interaction processes and avoiding service interruptions, thereby improving network handover efficiency and ensuring session and service continuity.

[0157] Please see Figure 11 , Figure 11 This is a schematic flowchart of a sub-step for switching from a 4G session to a 5G session and inserting an I-SMF, provided by an embodiment of the present invention. Specifically, it may include the following steps S401 to S403.

[0158] Step S401: When the session context request is a session context creation request, a session context creation request is sent to the first gateway converged network element. The session context creation request is generated by the access management network element in the core network based on the relocation request sent by the mobility management network element. The first gateway converged network element is a network element that merges the packet data network gateway control network element and the session management network element in the core network.

[0159] Please see Figure 12 , Figure 12 This is a schematic interaction diagram illustrating the insertion of an I-SMF during a 4G session handover to 5G, provided by an embodiment of the present invention. It should be noted that in this embodiment, the User Equipment (UE) has already established a PDN connection in the 4G radio access network. When the 4G base station needs to hand over the UE from a 4G session to a 5G session, the 4G base station sends a HANDOVERREQUIRED message to the Mobility Management Element (MME), informing the MME that a UE needs to perform a session handover.

[0160] In some embodiments, the Mobility Management Element (MME) sends a Forward Relocation Request to the Access Management Element (AMF) upon receiving a handover request. The relocation request includes the node name of the SGW-C. The AMF can determine whether the session needs to be inserted into the I-SMF based on the location of the User Equipment (UE) and the service area information of the SMF. It then queries the NRF to obtain the control plane converged network element based on the SGW-C node name carried in the relocation request. Finally, it sends a Session Context Creation Request to the control plane converged network element. This Session Context Creation Request may carry PDN connection information between the UE and the 4G base station, etc.

[0161] For example, the control plane converged network element needs to determine the type of the session context request. When it determines that the session context request is a request to obtain session context, it sends a session creation request to the first gateway converged network element. If the first gateway converged network element adopts a dynamic PCC (Policy and Charging Control) policy, it initiates a policy update request to the PCRF+PCF based on the session creation request.

[0162] Step S402: Receive the session creation response returned by the first gateway converged network element according to the session creation request, and perform the first PFCP session update with the user plane converged network element according to the session creation response.

[0163] For example, a session creation request may include, but is not limited to, information such as PDU session ID, QFI (Qos Flow ID), QoS configuration, and core network tunnel.

[0164] In this embodiment of the invention, the control plane converged network element can update the core network tunnel information by performing a first PFCP session update with the user plane converged network element.

[0165] It should be noted that, in this embodiment of the invention, the specific process of initiating a network handover procedure to enable the user equipment to switch between a 4G session and a 5G session includes step S403.

[0166] Step S403: After performing the first PFCP session update with the user plane converged network element, establish a second service tunnel and a second indirect forwarding tunnel between the 5G base station and the user plane converged network element, so that the access management network element can switch the user equipment from a 4G session to a 5G session based on the established second service tunnel and second indirect forwarding tunnel.

[0167] It is understandable that when switching user equipment from a 4G session to a 5G session, a second service tunnel and a second indirect forwarding tunnel need to be established between the 5G base station and the user plane converged network element so that uplink and downlink data can be transmitted through the established second service tunnel.

[0168] By performing the first PFCP session update with the user plane converged network element and establishing the second service tunnel and the second indirect forwarding tunnel between the 5G base station and the user plane converged network element, the access management network element can switch the user equipment from the 4G session to the 5G session based on the established second service tunnel and the second indirect forwarding tunnel. This ensures that the PFCP session remains unchanged during the network handover process, without the need to establish multiple PFCP sessions, thereby reducing the performance loss to the UPF.

[0169] Please see Figure 13 , Figure 13 This is a schematic flowchart of the sub-steps in step S403, which involves establishing the second service tunnel and the second indirect forwarding tunnel between the 5G base station and the user plane converged network element. Specifically, it may include the following steps S4031 to S4036.

[0170] Step S4031: Send a session creation context response containing second tunnel information to the access management network element, so that the access management network element sends a handover request to the 5G base station based on the second tunnel information.

[0171] For example, after receiving the Create Session Context response, the Access Management Element (AMF) can send a Handover Request to the 5G base station based on the second tunnel information carried in the Create Session Context response. The Handover Request is used to request the 5G base station to establish wireless network resources.

[0172] For example, the second tunnel information can be the tunnel information corresponding to the S1-U tunnel.

[0173] Step S4032: Receive the update session context request sent by the access management network element, wherein the update session context request is generated by the access management network element based on the handover response returned by the 5G base station based on the handover request, and the update session context request includes the third tunnel information corresponding to the second service tunnel and the second indirect forwarding tunnel.

[0174] For example, after receiving the handover response returned by the 5G base station based on the handover request, the access management network element (AMF) can send an update session context request to the control plane converged network element.

[0175] It should be noted that the third tunnel information refers to the tunnel information between the second service tunnel and the second indirect forwarding tunnel, used to establish the second service tunnel and the second indirect forwarding tunnel. In this embodiment of the invention, the second indirect service tunnel can be the N3 tunnel.

[0176] For example, the third tunnel information may include the user plane address and TEID of the N3 tunnel. At this point, the 5G base station is ready to transmit packet data units.

[0177] By obtaining the third tunnel information, a second service tunnel and a second indirect forwarding tunnel can be subsequently established between the 5G base station and the user plane converged network element based on the third tunnel information.

[0178] Step S4033: Perform a third PFCP session update with the user plane converged network element according to the update session context request, so as to send the third tunnel information to the user plane converged network element.

[0179] For example, when the control plane converged network element and the user plane converged network element perform a third PFCP session update, the user plane address and TEID of the N3 tunnel can be sent to the user plane converged network element.

[0180] Step S4034: Send an update session context response to the access management network element, so that the access management network element sends a relocation response to the mobility management network element based on the update session context response.

[0181] For example, after completing the third PFCP session update, the control plane converged network element can send an Nsmf_PDUSession_Update SM Context Response to the access management network element (AMF). This update session context response may include the PDU session ID, the 4G base station bearer establishment list, and core network tunnel information, etc.

[0182] In some embodiments, the Access Management Element (AMF) can send a Forward Relocation Response and core network tunnel information to the Mobility Management Element (MME) based on the Update Session Context response. For indirect data forwarding, the MME sends a Create Indirect Data Forwarding Tunnel Request to the Combo SMF (SGW-C).

[0183] Step S4035: Receive the request to create an indirect data forwarding tunnel sent by the mobility management network element according to the relocation response, and perform a fourth PFCP session update with the user plane converged network element according to the request to create an indirect data forwarding tunnel, so as to update the address information corresponding to the indirect forwarding mode of the user plane converged network element.

[0184] For example, when the control plane converged network element and the user plane converged network element perform a fourth PFCP session update, the address information corresponding to the indirect forwarding method of the user plane converged network element can be updated.

[0185] Step S4036: Send a response to the Mobility Management Network Element containing the third tunnel information to create an indirect data forwarding tunnel, so that the Mobility Management Network Element establishes the second service tunnel and the second indirect forwarding tunnel between the 5G base station and the user plane converged network element based on the third tunnel information.

[0186] For example, after completing the fourth PFCP session update, the control plane converged network element can send a creation indirect data forwarding tunnel response containing third tunnel information to the mobility management network element (MME).

[0187] In some embodiments, after receiving the response to create an indirect data forwarding tunnel, the Mobility Management Element (MME) sends a Handover Command to the 4G base station to notify the 4G base station to complete handover preparation. The 4G base station then sends the handover command to the User Equipment (UE) to notify the UE to switch to the target access network. The target access network refers to the 5G radio access network.

[0188] For example, after receiving a handover command, the User Equipment (UE) can release the 4G base station bearer and the corresponding 4G base station radio-side bearer that were rejected by the target cell. After the UE successfully hands over to the 5G base station, it sends a handover completion message to the 5G base station. At this time, the downlink data forwarding path is: 4G base station -> User plane converged network element -> 5G base station -> User Equipment (UE).

[0189] In some embodiments, the 5G base station can send a HANDOVERNOTIFY message to the Access Management Element (AMF) to notify the AMF that the User Equipment (UE) is located in the target cell. Upon receiving the handover notification message, the AMF can send a Forward Relocation Complete Notification message to the Mobility Management Element (MME), causing the MME to return a Forward Relocation Complete Acknowledge message. At this time, the MME will start a timer to monitor the resource release status of the 4G base station and the Service Grid Gateway (SGW).

[0190] In some embodiments, the access management network element (AMF) returns an Nsmf_PDUSession_UpdateSMContextRequest (update session context request) so that the control plane converged network element can perform a PFCP session update with the user plane converged network element according to the update session context request to update the local user plane. After completing the PFCP session update, the control plane converged network element can also send an update session request to the first gateway converged network element so that the first gateway converged network element can perform a PFCP session update with the second gateway converged network element to update the core network tunnel information of the second gateway converged network element.

[0191] The update session request is used to indicate that the switchover of the N26 tunnel is complete.

[0192] For example, after completing the PFCP session update, the first gateway converged network element can also return an update session response to the control plane converged network element, so that the control plane converged network element can send an update session context response to the access management network element (AMF) based on the update session response.

[0193] Please see Figure 14 , Figure 14 This is an illustrative flowchart of a sub-step for switching a 4G session to a 5G session by inserting an I-SMF when there is no N26 tunnel between the AMF and the MME, provided by an embodiment of the present invention. Specifically, it may include the following steps S501 to S504.

[0194] Step S501: When the session context request is a session context creation request, determine whether the session context creation request is a new protocol data unit session request and whether it is executed locally.

[0195] Please see Figure 15 , Figure 15 This is a schematic interaction diagram illustrating the handover of a 4G session to 5G via I-SMF when there is no N26 tunnel between the AMF and MME, according to an embodiment of the present invention. In this embodiment, the User Equipment (UE) has already established a PDN connection in the 4G radio access network. When the UE needs to hand over from the 4G base station to the 5G base station, the UE sends a registration request to the 5G base station, causing the 5G base station to forward the registration request to the Access Management Element (AMF). The AMF performs authentication and security procedures with the UE based on the registration request. When the AMF does not support an N26 tunnel, the AMF can obtain the user's DNN and PGW-C or SGW-C address from the HSS+UDM and send a registration subscription request to the HSS+UDM to instruct the HSS+UDM not to cancel the registration of the MME.

[0196] In some embodiments, the Access Management Element (AMF) can obtain the User MM policy from the PCRF+PCF and distribute the User MM policy to the User Equipment (UE). For example, the AMF can send the User MM policy to the UE via a registration acceptance message; the registration acceptance message may also include an "Interworking without N26" indicator. Here, "Interworking without N26" indicates that there is no N26 tunnel between the AMF and the Mobility Management Element (MME). After receiving the registration acceptance message, the UE can return a registration completion message to the AMF.

[0197] In some embodiments, when a user equipment (UE) receives a registration acceptance message containing the "Interworking without N26" indicator, it sends a PDU session establishment request to the access management network element (AMF), so that the AMF sends a session context creation request to the control plane converged network element based on the PDU session establishment request.

[0198] For example, when the access management network element (AMF) receives a PDU session establishment request, it determines whether the PDU session establishment request is a new PDU session; if it determines that the PDU session establishment request is a new PDU session, it selects the SMF corresponding to the PDU session establishment request. Here, SMF refers to the SMF in the control plane converged network element.

[0199] It should be noted that local execution means that the control plane converged network element can handle the request to create a session context locally.

[0200] Step S502: When it is determined that the request to create a session context is a new protocol data unit session request and is executed locally, a request to create a session context is sent to the access management network element in the core network, and the first PFCP session is updated with the user plane converged network element.

[0201] It should be noted that the control plane converged network element and the user plane converged network element perform the first PFCP session update to request the user plane converged network element to allocate the endpoints of the left N3 tunnel and the right N9 tunnel of the I-UPF. By performing the first PFCP session update, error messages can be avoided when the I-UPF receives uplink and downlink data during the PDU session establishment process.

[0202] It should be noted that, in this embodiment of the invention, the specific process of initiating a network handover procedure to enable the user equipment to switch between a 4G session and a 5G session includes steps S503 and S504.

[0203] Step S503: Send a session creation request to the first gateway converged network element so that the first gateway converged network element and the second gateway converged network element can perform a fifth PFCP session update. The first gateway converged network element is a network element that merges the packet data network gateway control network element and the session management network element in the core network. The second gateway converged network element is a network element that merges the packet data network gateway user plane network element and the user plane network element in the core network.

[0204] For example, a session creation request may include downlink port information corresponding to the N9 tunnel, etc.

[0205] In some embodiments, when the first gateway converged network element and the second gateway converged network element perform a fifth PFCP session update, the first gateway converged network element sends the charging policy and control policy to the second gateway converged network element. The first gateway converged network element can also register a session with the HSS+UDM according to the charging policy and control policy. For example, registering a session with the UDM.

[0206] Step S504: Receive the session creation response sent by the first gateway converged network element. The session creation response indicates that the first gateway converged network element has completed the switch of the user equipment from a 4G session to a 5G session.

[0207] For example, the control plane converged network element receives a session creation response sent by the first gateway converged network element, wherein the session creation response is generated by the first gateway converged network element and the unified data management network element UDM registering a session; the session creation response is used to indicate that the first gateway converged network element has completed the switch of the user equipment from a 4G session to a 5G session.

[0208] In some embodiments, the control plane converged network element can also send a transmission message to the access management network element (AMF) so that the AMF can establish a session with the 5G base station based on the transmission message and establish an indirect forwarding tunnel between the 5G base station and the user plane converged network element.

[0209] For example, the transmitted message may include the user address, the endpoints of the left N3 tunnel and the right N9 tunnel of the I-UPF, and the control policy.

[0210] In some embodiments, the control plane converged network element may also receive an update session context request sent by the access management network element AMF, wherein the update session context request includes N3 tunnel information corresponding to the indirect forwarding tunnel;

[0211] In this embodiment of the invention, after the access management network element (AMF) establishes a session with the 5G base station, the access management network element (AMF) can also send an update session context request to the control plane converged network element.

[0212] It should be noted that the N3 tunnel information is generated by the access management network element AMF through interaction with the user equipment (UE) and the 5G base station based on the user address, the endpoints of the left N3 tunnel and the right N9 tunnel of the I-UPF, and the control policy.

[0213] For example, a control plane converged network element can request an update session context to perform a PFCP session update with a user plane converged network element, thereby sending the tunnel information corresponding to the indirect forwarding tunnel to the user plane converged network element and updating the tunnel information. For example, the N3 tunnel information can be sent to the user plane converged network element.

[0214] For example, after the control plane converged network element and the user plane converged network element complete the PFCP session update, they can also send an update session context response to the access management network element (AMF). The update session context response includes a field value indicating whether the N3 tunnel was successfully updated.

[0215] It should be noted that the update session context response is used to indicate the completion of establishing an indirect forwarding tunnel.

[0216] In this embodiment of the invention, the specific process of switching a 5G session with I-SMF to a 4G session when there is no N26 tunnel between AMF and MME is similar to the process of switching a 4G session to a 5G session with I-SMF when there is no N26 tunnel between AMF and MME. For the specific process, please refer to the above embodiment. The specific details will not be repeated here.

[0217] By performing a first PFCP session update with the user plane converged network element and sending a session creation request to the first gateway converged network element, so that the first gateway converged network element and the second gateway converged network element can perform a fifth PFCP session update, it is possible to switch user equipment from 4G session to 5G session when there is no N26 tunnel between AMF and MME, thereby improving the efficiency of network handover and ensuring the continuity of sessions and services.

[0218] The network handover method, converged network element, communication system, and storage medium provided in the above embodiments reduce control plane resource consumption and allow more users to access the network by merging the serving gateway control plane network element with the intermediate session management network element. By merging the serving gateway user plane network element with the intermediate user plane network element, the 4G base station supports local traffic offloading services, minimizing traffic impact on the bearer network during service handover. By performing a first PFCP session update with the user plane converged network element based on a session context request, a network handover process can be initiated, enabling user equipment to switch between 4G and 5G sessions, thereby simplifying the 4G / 5G interoperability handover process and reducing the load on the existing network serving network element (SGW). By performing a first PFCP session update with the user plane converged network element based on a session creation request, the PFCP session remains unchanged during network handover, eliminating the need to establish multiple PFCP sessions and reducing performance loss on the UPF. By establishing a first service tunnel and a first indirect forwarding tunnel between the 4G base station and the user plane converged network element based on first tunnel information, the network handover process can be maintained. This allows subsequent uplink and downlink data to be transmitted through the first service tunnel, reducing data transfer processes. Updating the user plane forwarding path minimizes changes, effectively reducing network handover latency and improving efficiency. By updating the first PFCP session with the user plane converged network element and establishing a second service tunnel and a second indirect forwarding tunnel between the 5G base station and the user plane converged network element, the access management network element can switch user equipment from 4G to 5G sessions based on these tunnels. This maintains the PFCP session during network handover, eliminating the need to establish multiple PFCP sessions and reducing performance loss to the UPF. Furthermore, updating the first PFCP session with the user plane converged network element and sending a session creation request to the first gateway converged network element, enabling a fifth PFCP session update between the first and second gateway converged network elements, allows user equipment to switch from 4G to 5G sessions even when there is no N26 tunnel between the AMF and MME, improving network handover efficiency and ensuring session and service continuity.

[0219] Please see Figure 16 , Figure 16 This is a schematic flowchart illustrating another network handover method provided in an embodiment of the present invention. This network handover method can be applied to user plane converged network elements. By requesting PFCP session updates with control plane converged network elements based on the session context, the interaction process can be reduced, thereby improving the efficiency of network handover and ensuring session and service continuity. The network handover method includes steps S601 and S602.

[0220] Step S601: Receive the PFCP session update request sent by the control plane fusion network element, wherein the control plane fusion network element is a network element formed by merging the service gateway control plane network element and the intermediate session management network element in the core network.

[0221] It should be noted that the control plane converged network element is the network element formed by merging the service gateway control plane network element and the intermediate session management network element in the core network; the user plane converged network element is the network element formed by merging the service gateway user plane network element and the intermediate user plane network element in the core network.

[0222] In some embodiments, the control plane converged network element can send a PFCP session update request to the user plane converged network element based on a session creation request sent by the mobility management network element (MME).

[0223] In some embodiments, the control plane converged network element may also send a PFCP session update request to the user plane converged network element based on the session creation response returned by the first gateway converged network element based on the session creation request.

[0224] In other embodiments, the control plane converged network element can also send a PFCP session update request to the user plane converged network element based on the session context request created by the access management network element (AMF).

[0225] Step S602: Perform a first PFCP session update with the control plane converged network element according to the PFCP session update request to initiate a network handover process, enabling the user equipment to switch between 4G and 5G sessions.

[0226] In this embodiment of the invention, a network switching process is initiated to switch the user equipment from a 4G session to a 5G session, or to switch the user equipment from a 5G session to a 4G session.

[0227] The specific process of initiating the network handover procedure to switch the user equipment between 4G and 5G sessions can be found in the detailed description of the above embodiments, and the specific process will not be repeated here.

[0228] The network handover method, converged network element, communication system, and storage medium provided in the above embodiments reduce control plane resource consumption and allow more users to access the network by merging the serving gateway control plane network element with the intermediate session management network element. By merging the serving gateway user plane network element with the intermediate user plane network element, the 4G base station supports local traffic offloading services, minimizing the traffic impact on the bearer network during service handover. By requesting PFCP session updates with the converged control plane network element based on the session context, the interaction process can be reduced, thereby improving the efficiency of network handover and ensuring the continuity of sessions and services.

[0229] This invention also provides a storage medium for computer-readable storage, wherein the storage medium stores one or more programs that can be executed by one or more processors to implement the steps of any of the network handover methods provided in the specification of this invention.

[0230] For example, when the program is loaded by the processor, it can perform the following steps:

[0231] Based on the session context request, a first PFCP session update is performed with the user plane converged network element to initiate a network handover process, enabling the user equipment to switch between 4G and 5G sessions. The user plane converged network element is a network element formed by merging the service gateway user plane network element and the intermediate user plane network element in the core network.

[0232] For example, once the program is loaded by the processor, it can perform the following steps:

[0233] The system receives a PFCP session update request sent by a control plane converged network element, wherein the control plane converged network element is a network element formed by merging the serving gateway control plane network element and the intermediate session management network element in the core network; and performs a first PFCP session update with the control plane converged network element according to the PFCP session update request to initiate a network handover process, enabling the user equipment to switch between 4G and 5G sessions.

[0234] The storage medium can be an internal storage unit of the control plane converged network element or the user plane converged network element described in the foregoing embodiments, such as a hard disk or memory of the control plane converged network element or the user plane converged network element. Alternatively, the storage medium can be an external storage device of the control plane converged network element or the user plane converged network element, such as a plug-in hard disk, Smart Media Card (SMC), Secure Digital (SD) card, or Flash Card equipped on the control plane converged network element or the user plane converged network element.

[0235] It will be understood by those skilled in the art that all or some of the steps, systems, or apparatuses disclosed above, and their functional modules / units, can be implemented as software, firmware, hardware, or suitable combinations thereof. In hardware embodiments, the division between functional modules / units mentioned in the above description does not necessarily correspond to the division of physical components; for example, a physical component may have multiple functions, or a function or step may be performed collaboratively by several physical components. Some or all physical components may be implemented as software executed by a processor, such as a central processing unit, digital signal processor, or microprocessor, or as hardware, or as an integrated circuit, such as an application-specific integrated circuit. Such software may be distributed on a computer-readable medium, which may include computer storage media (or non-transitory media) and communication media (or transient media). As is known to those skilled in the art, the term computer storage media includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules, or other data). Computer storage media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, digital versatile disc (DVD) or other optical disc storage, magnetic cartridges, magnetic tape, disk storage or other magnetic storage devices, or any other medium that can be used to store desired information and can be accessed by a computer. Furthermore, it is well known to those skilled in the art that communication media typically contain computer-readable instructions, data structures, program modules, or other data in modulated data signals such as carrier waves or other transmission mechanisms, and may include any information delivery medium.

[0236] It should be understood that the term "and / or" as used in this specification and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes such combinations. It should be noted that, herein, the terms "comprising," "including," or any other variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or system. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or system that includes that element.

[0237] The sequence numbers of the above embodiments of the present invention are merely for descriptive purposes and do not represent the superiority or inferiority of the embodiments. The above descriptions are only specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A network handover method applied to a control plane converged network element, wherein the control plane converged network element is a network element formed by merging the serving gateway control plane network element and the intermediate session management network element in the core network, the method comprising: According to the session context request, the first PFCP session update is performed with the user plane converged network element to initiate the network handover process, enabling the user equipment to switch between 4G and 5G sessions. The user plane converged network element is a network element formed by merging the service gateway user plane network element and the intermediate user plane network element in the core network. The session context request includes an obtain session context request and a create session context request. The obtain session context request is used to obtain the context of the 5G session in order to switch the 5G session to a 4G session. The create session context request is used to create the context of the 5G session in order to switch the 4G session to a 5G session. The network switching method is applied to: Scenarios where a 5G session with I-SMF switches to a 4G session; scenarios where a 4G session switches to 5G with I-SMF inserted; scenarios where the user equipment is in an idle state and a 5G session with I-SMF switches to a 4G session; and scenarios where a 4G session switches to 5G with I-SMF inserted when there is no N26 tunnel between the AMF and the MME.

2. The network handover method of claim 1, wherein, The step of performing the first PFCP session update with the user plane converged network element according to the session context request includes: When the session context request is a request to obtain session context, a request to obtain session context response is sent to the access management network element in the core network, so that the access management network element sends a relocation request to the mobility management network element in the core network according to the request to obtain session context response; The system receives a session creation request sent by the mobility management network element based on the relocation request, and performs the first PFCP session update with the user plane convergence network element based on the session creation request.

3. The network switching method according to claim 2, characterized in that, The network handover initiation process enables the user equipment to switch between a 4G session and a 5G session, including: After performing the first PFCP session update with the user plane converged network element, the first tunnel information between the user plane converged network element and the 5G base station is obtained; Based on the first tunnel information, a first service tunnel and a first indirect forwarding tunnel are established between the 4G base station and the user plane converged network element, so that the access management network element can switch the user equipment from a 5G session to a 4G session based on the established first service tunnel and the first indirect forwarding tunnel.

4. The network switching method according to claim 3, characterized in that, Before establishing the first service tunnel and the first indirect forwarding tunnel between the 4G base station and the user plane converged network element based on the first tunnel information, the method further includes: Send a session creation response containing the first tunnel information to the mobility management network element, so that the mobility management network element sends a handover request to the 4G base station based on the first tunnel information; The system receives a request to create an indirect data forwarding tunnel from the mobility management network element, wherein the request to create an indirect data forwarding tunnel is generated by the mobility management network element based on the handover response returned by the 4G base station based on the handover request; According to the request to create an indirect data forwarding tunnel, a PFCP session update request is sent to the user plane converged network element to request the establishment of the first service tunnel and the first indirect forwarding tunnel. The system receives a PFCP session update response returned by the user plane converged network element in accordance with the PFCP session update request, wherein the PFCP session update response includes address information corresponding to the first service tunnel and the first indirect forwarding tunnel; The step of establishing a first service tunnel and a first indirect forwarding tunnel between the 4G base station and the user plane converged network element based on the first tunnel information includes: According to the PFCP session update response, a Create Indirect Data Forwarding Tunnel response is sent to the Mobility Management Network Element, so that the Mobility Management Network Element sends a Relocation Response to the Access Management Network Element according to the Create Indirect Data Forwarding Tunnel response, wherein the Relocation Response includes the address information and tunnel endpoint identifier corresponding to the first service tunnel and the first indirect forwarding tunnel. The access management network element receives an update session context request sent according to the relocation response, wherein the update session context request includes the address information and the tunnel endpoint identifier corresponding to the first service tunnel and the first indirect forwarding tunnel; Based on the address information, the tunnel endpoint identifier, and the user plane converged network element, the first indirect forwarding tunnel is established, and an update session context response is returned to the access management network element. The update session context response is used to indicate that the establishment of the first service tunnel and the first indirect forwarding tunnel is complete.

5. The network switching method according to claim 4, characterized in that, After establishing the first service tunnel and the first indirect forwarding tunnel between the 4G base station and the user plane converged network element based on the first tunnel information, the method further includes: When the update bearer request sent by the mobility management network element is received, the update bearer request is sent to the first gateway converged network element so that the first gateway converged network element and the second gateway converged network element can perform a second PFCP session update to update the user plane forwarding path. The first gateway converged network element is a network element that merges the packet data network gateway control network element and the session management network element in the core network, and the second gateway converged network element is a network element that merges the packet data network gateway user plane network element and the user plane network element in the core network. The user equipment receives the update bearer response returned by the first gateway converged network element and sends the update bearer response to the mobility management network element so that the user equipment initiates a tracking area update process to the mobility management network element.

6. The network handover method according to claim 1, characterized in that, The step of performing the first PFCP session update with the user plane converged network element according to the session context request includes: When the session context request is a request to obtain session context, a request to obtain session context response is sent to the access management network element in the core network, so that the access management network element sends a context response to the mobility management network element in the core network according to the request to obtain session context response. The request to obtain session context is generated by the access management network element according to the context request sent by the mobility management network element. The system receives a session creation request sent by the mobility management network element based on the context response, and performs the first PFCP session update with the user plane convergence network element based on the session creation request.

7. The network handover method according to claim 6, characterized in that, The network handover initiation process enables the user equipment to switch between a 4G session and a 5G session, including: After performing the first PFCP session update with the user plane converged network element, an update bearer request is sent to the first gateway converged network element so that the first gateway converged network element and the second gateway converged network element can perform a third PFCP session update to update the user plane forwarding path. The first gateway converged network element is a network element that merges the packet data network gateway control network element and the session management network element in the core network, and the second gateway converged network element is a network element that merges the packet data network gateway user plane network element and the user plane network element in the core network. When the updated bearer response is received from the first gateway converged network element, a session creation response is sent to the mobility management network element so that the mobility management network element can perform a location update with the home user server based on the session creation response, thereby enabling the user equipment to switch from a 5G session to a 4G session. The home user server includes a converged unified data management network element.

8. The network handover method according to claim 1, characterized in that, The step of performing a first PFCP session update with the user plane converged network element according to the session context request includes: When the session context request is a session context creation request, a session context creation request is sent to the first gateway converged network element. The session context creation request is generated by the access management network element in the core network based on the relocation request sent by the mobility management network element. The first gateway converged network element is a network element that merges the packet data network gateway control network element and the session management network element in the core network. The system receives the session creation response returned by the first gateway converged network element based on the session creation request, and performs the first PFCP session update with the user plane converged network element based on the session creation response.

9. The network handover method according to claim 8, characterized in that, The network handover initiation process enables the user equipment to switch between a 4G session and a 5G session, including: After performing the first PFCP session update with the user plane converged network element, a second service tunnel and a second indirect forwarding tunnel are established between the 5G base station and the user plane converged network element, so that the access management network element can switch the user equipment from a 4G session to a 5G session based on the established second service tunnel and second indirect forwarding tunnel.

10. The network handover method according to claim 9, characterized in that, Before establishing the second service tunnel and the second indirect forwarding tunnel between the 5G base station and the user plane converged network element, the method further includes: Send a session creation context response containing second tunnel information to the access management network element, so that the access management network element sends a handover request to the 5G base station based on the second tunnel information; The access management network element receives an update session context request sent by the access management network element, wherein the update session context request is generated by the access management network element based on the handover response returned by the 5G base station based on the handover request, and the update session context request includes third tunnel information corresponding to the second service tunnel and the second indirect forwarding tunnel; According to the update session context request, a third PFCP session update is performed with the user plane converged network element to send the third tunnel information to the user plane converged network element; Send an update session context response to the access management network element, so that the access management network element sends a relocation response to the mobility management network element based on the update session context response; The establishment of the second service tunnel and the second indirect forwarding tunnel between the 5G base station and the user plane converged network element includes: The system receives a request to create an indirect data forwarding tunnel from the mobility management network element based on the relocation response, and performs a fourth PFCP session update with the user plane converged network element based on the request to create an indirect data forwarding tunnel, so as to update the address information corresponding to the indirect forwarding mode of the user plane converged network element. The mobile management network element sends a response to create an indirect data forwarding tunnel containing the third tunnel information, so that the mobile management network element can establish the second service tunnel and the second indirect forwarding tunnel between the 5G base station and the user plane converged network element based on the third tunnel information.

11. The network handover method according to claim 1, characterized in that, The step of performing a first PFCP session update with the user plane converged network element according to the session context request includes: When the session context request is a session context creation request, determine whether the session context creation request is a new protocol data unit session request and whether it is executed locally; When it is determined that the request to create a session context is a new protocol data unit session request and is executed locally, a request to create a session context is sent to the access management network element in the core network, and the first PFCP session is updated with the user plane converged network element.

12. The network handover method according to claim 11, characterized in that, The network handover initiation process enables the user equipment to switch between a 4G session and a 5G session, including: A session creation request is sent to the first gateway converged network element so that the first gateway converged network element and the second gateway converged network element can perform a fifth PFCP session update. The first gateway converged network element is a network element that merges the packet data network gateway control network element and the session management network element in the core network. The second gateway converged network element is a network element that merges the packet data network gateway user plane network element and the user plane network element in the core network. The system receives a session creation response from the first gateway converged network element, which indicates that the first gateway converged network element has completed the switch of the user equipment from a 4G session to a 5G session.

13. A network handover method applied to a user plane converged network element, wherein the user plane converged network element is a network element formed by merging the serving gateway user plane network element and intermediate user plane network elements in the core network, the method comprising: Receive PFCP session update requests sent by control plane converged network elements, wherein the control plane converged network element is a network element formed by merging the service gateway control plane network element and the intermediate session management network element in the core network; The first PFCP session update is performed with the control plane converged network element according to the PFCP session update request to initiate the network handover process, enabling the user equipment to switch between 4G and 5G sessions. The network switching method is applied to: Scenarios where a 5G session with I-SMF switches to a 4G session; scenarios where a 4G session switches to 5G with I-SMF inserted; scenarios where the user equipment is in an idle state and a 5G session with I-SMF switches to a 4G session; and scenarios where a 4G session switches to 5G with I-SMF inserted when there is no N26 tunnel between the AMF and the MME.

14. A converged network element, characterized in that, It includes a processor, a memory, a computer program stored in the memory and executable by the processor, and a data bus for implementing connection communication between the processor and the memory, wherein the computer program, when executed by the processor, implements the network switching method as described in any one of claims 1 to 12.

15. A converged network element, characterized in that, It includes a processor, a memory, a computer program stored in the memory and executable by the processor, and a data bus for implementing communication between the processor and the memory, wherein the computer program, when executed by the processor, implements the network switching method as described in claim 13.

16. A communication system, characterized in that, The communication system includes control plane converged network elements and user plane converged network elements. The control plane converged network element is a network element formed by merging the serving gateway control plane network element and the intermediate session management network element in the core network. The user plane converged network element is a network element formed by merging the serving gateway user plane network element and the intermediate user plane network element in the core network. The control plane converged network element is used to send PFCP session update requests to the user plane converged network element; The user plane converged network element is used to receive the PFCP session update request sent by the control plane converged network element, and perform a first PFCP session update with the control plane converged network element according to the PFCP session update request to initiate a network handover process, enabling the user equipment to switch between 4G and 5G sessions. The communication system is used in: Scenarios where a 5G session with I-SMF switches to a 4G session; scenarios where a 4G session switches to 5G with I-SMF inserted; scenarios where the user equipment is in an idle state and a 5G session with I-SMF switches to a 4G session; and scenarios where a 4G session switches to 5G with I-SMF inserted when there is no N26 tunnel between the AMF and the MME.

17. A storage medium for readable storage, characterized in that, The storage medium stores one or more programs, which can be executed by one or more processors to achieve: The network handover method as described in any one of claims 1 to 12; or The network switching method as described in claim 13.

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