Network switching method and device

Abstract

The invention discloses a network switching method and device, relates to the technical field of communication, and can support terminal equipment to switch between different visited networks, ensure the service continuity of the terminal equipment in the switching process and improve the communication performance. The method comprises: a first session management network element of a first network receiving a first request from a first mobility management network element of the first network, the first request being used for requesting to establish a session for a terminal device, the first request comprising identification information of a second session management network element of a second network, the second network being a home network of the terminal device; sending a second request for requesting to acquire context information of the terminal equipment to a second session management network element, receiving a second response from the second session management network element, and establishing a session for the terminal equipment according to the second response; the second response comprises context information of the terminal equipment stored in a third session management network element, and the third session management network element is a network element for establishing a session for the terminal equipment in the third network.

Description

Technical Field

[0001] The present application relates to the field of communication technology, and in particular to a network switching method and device. Background Art

[0002] In the communication system, the core network and access network can be deployed based on the network sharing mechanism, that is, the shared access network can be allowed to access different core networks respectively, so as to realize the sharing of access network resources between operators, improve network quality and reduce network deployment costs.

[0003] The shared access network and the core network may be directly connected or indirectly connected. For example, the shared access network may be directly connected to the core network 1, or the shared access network may be indirectly connected to the core network 2 through the core network 1.

[0004] Based on the above network sharing mechanism, the terminal device can access the home network (such as core network 2) through the visited network (such as core network 1) based on the shared access network. When the terminal device needs to switch from accessing the home network through the visited network 1 to accessing the home network through the visited network 2 during the mobile process, if there is no connection between the visited network 1 and the visited network 2, how the terminal device can switch from the visited network 1 to the visited network 2 while ensuring the service continuity of the terminal device during the switching process has become a technical problem that needs to be solved urgently. Summary of the invention

[0005] The embodiments of the present application provide a network switching method and device, which can support terminal equipment to switch between different visited networks, and at the same time, ensure the service continuity of the terminal equipment during the switching process and improve the communication performance.

[0006] In a first aspect, an embodiment of the present application provides a network switching method, the execution subject of the method may be a first session management network element of a first network, or a chip, a chip system or a system on chip of the first session management network element. The method comprises: receiving a first request from a first mobility management network element of a first network, the first request being used to request to establish a session for a terminal device, the first request comprising identification information of a second session management network element of a second network, the second network being the home network of the terminal device; sending a second request to the second session management network element, receiving a second response from the second session management network element, and establishing a session for the terminal device according to the second response; wherein the second request is used to request to obtain context information of the terminal device, the second response comprising the context information of the terminal device stored in a third session management network element, the third session management network element being a network element in a third network that establishes a session for the terminal device.

[0007] Based on the first aspect, when the terminal device needs to switch from the third network to the first network, the second session management network element of the terminal device's home network (i.e., the second network) can assist the first session management network element in obtaining the context information of the terminal device stored in the third session management network element. Then, the second session management network element can establish a session for the terminal device based on the context information of the terminal device, thereby realizing the switching of the terminal device between different visited networks (i.e., realizing the switching of the terminal device between the third network and the first network), while ensuring the business continuity of the terminal device during the switching process and improving communication performance.

[0008] In one possible design, the first request also includes one or more of the following: identification information of the session established by the third network for the terminal device, and identification information of the third session management network element.

[0009] In one possible design, the second request includes one or more of the following: identification information of the session established by the third network for the terminal device, and identification information of the third session management network element.

[0010] Based on the above two possible designs, by carrying the identification information of the session established by the third network for the terminal device and / or the identification information of the third session management network element in the first request and the second request, the second session management network element can determine the corresponding third session management network element based on the identification information of the session or the identification information of the third session management network element, and then obtain the context information of the terminal device.

[0011] In one possible design, a session is established for the terminal device based on the second response, including: obtaining first tunnel information and second tunnel information, sending the first tunnel information to the first user plane network element, and sending a first response to the first mobility management network element; wherein the second response includes the first tunnel information and the second tunnel information, the first response includes the second tunnel information, and the first tunnel information is used to establish a data forwarding tunnel between the first user plane network element of the first network and the second user plane network element of the second network.

[0012] In one possible design, the second tunnel information is used to establish an uplink data forwarding tunnel between a source access network device of a third network and a third user plane network element of the third network.

[0013] Based on the above two possible designs, by forwarding the first tunnel information, the first user plane network element can be facilitated to communicate with the second user plane network element through the first tunnel information, and by forwarding the second tunnel information, the source access network device can be facilitated to communicate with the third user plane network element through the second tunnel information. This facilitates the subsequent establishment of a data forwarding tunnel between the source access network device, the third user plane network element, the second user plane network element, and the first user plane network element, and facilitates the subsequent source access network device to send the service data of the terminal device to the first user plane network element through the third user plane network element and the second user plane network element, thereby ensuring the service continuity of the terminal device during the switching process.

[0014] In a second aspect, an embodiment of the present application provides a network switching method, the execution subject of the method may be a first mobility management network element of a first network, or a chip, a chip system, or a system on chip of the first mobility management network element. The method includes: receiving a third request from a second mobility management network element of a second network; the third request is used to request to switch a terminal device from a third network to a first network, the second network being the home network of the terminal device; obtaining identification information of a second session management network element of the second network; sending a first request to a first session management network element of the first network; wherein the first request is used to request to establish a session for the terminal device, and the first request includes identification information of the second session management network element.

[0015] Based on the second aspect, when the terminal device needs to switch from the third network to the first network, the second mobility management network element of the terminal device's home network (i.e., the second network) can assist the third mobility management network element of the third network to pass the network switching request of the terminal device to the first mobility management network element of the first network. Then, the first mobility management network element can request the first session management network element to establish a session for the terminal device, thereby realizing the switching of the terminal device between the third network and the first network, while ensuring the business continuity of the terminal device during the switching process and improving communication performance.

[0016] In one possible design, obtaining identification information of a second session management network element of a second network includes: determining the identification information of the second session management network element based on a third request; wherein the third request includes the identification information of the second session management network element; or, the third request includes network slice information, and determining the identification information of the second session management network element based on the network slice information; or, randomly determining the identification information of the second session management network element based on a preset configuration.

[0017] Based on this possible design, the first mobility management network element can adopt one or more of the above-mentioned methods to select a second session management network element that can assist the terminal device in network switching, so that the first session management network element obtains the context information of the terminal device stored in the third session management network element through the second session management network element selected by the first mobility management network element, thereby ensuring the service continuity of the terminal device during the switching process and improving communication performance.

[0018] In one possible design, the third request includes global identification information of the target access network device, and before sending the first request to the first session management network element of the first network, the method also includes: determining the first session management network element based on the global identification information of the target access network device; or, the third request includes network slice information; before sending the first request to the first session management network element of the first network, the method also includes: determining the first session management network element based on the network slice information.

[0019] Based on this possible design, the first mobility management network element can adopt any of the above methods to select a suitable first session management network element for the terminal device to better provide network services for the terminal device and improve communication performance.

[0020] In one possible design, the third request also includes one or more of the following: identification information of the session established by the third network for the terminal device, and identification information of the third session management network element of the third network.

[0021] In one possible design, the first request also includes one or more of the following: identification information of the session established by the third network for the terminal device, and identification information of a third session management network element of the third network.

[0022] Based on the above two possible designs, by carrying the identification information of the session established by the third network for the terminal device and / or the identification information of the third session management network element in the third request and the first request, the second session management network element can determine the corresponding third session management network element based on the identification information of the session or the identification information of the third session management network element, and then obtain the context information of the terminal device.

[0023] In one possible design, a first response is received from a first session management network element; wherein the first response includes second tunnel information; and a third response is sent to a second mobility management network element; wherein the third response is used to indicate that the first network allows the terminal device to switch from the third network to the first network, and the third response includes identification information of the first mobility management network element and the second tunnel information.

[0024] In one possible design, the second tunnel information is used to establish an uplink data forwarding tunnel between a source access network device of a third network and a third user plane network element of the third network.

[0025] Based on the above two possible designs, by forwarding the second tunnel information, the source access network device can realize communication with the third user plane network element through the second tunnel information. This facilitates the subsequent establishment of a data forwarding tunnel between the source access network device, the third user plane network element, the second user plane network element, and the first user plane network element, and facilitates the subsequent source access network device to send the service data of the terminal device to the first user plane network element through the third user plane network element and the second user plane network element, thereby ensuring the service continuity of the terminal device during the switching process.

[0026] In a third aspect, an embodiment of the present application provides a network switching method, the execution subject of the method may be a second mobility management network element of a second network, or may be a chip, a chip system, or a system on chip of the second mobility management network element. The method comprises: receiving a fourth request from a third mobility management network element of a third network; wherein the fourth request is used to request to switch a terminal device from the third network to a first network, and the second network is a home network of the terminal device; obtaining identification information of a second session management network element of the second network; sending a third request to a first mobility management network element of the first network; wherein the third request is used to request to switch a terminal device from the third network to the first network, and the third request includes identification information of the second session management network element.

[0027] Based on the third aspect, when the terminal device needs to switch from the third network to the first network, the second mobility management network element of the terminal device's home network (i.e., the second network) can assist the third mobility management network element of the third network to pass the network switching request of the terminal device to the first mobility management network element of the first network, and then the first network establishes a session for the terminal device to realize the switching of the terminal device between the third network and the first network, while ensuring the business continuity of the terminal device during the switching process and improving communication performance.

[0028] In one possible design, obtaining identification information of a second session management network element of a second network includes: determining identification information of the second session management network element according to a fourth request; wherein the fourth request includes identification information of the second session management network element; or, the fourth request includes identification information of a session established by a third network for a terminal device, and determining identification information of the second session management network element from an association relationship between pre-stored identification information of the session and identification information of the second session management network element according to the identification information of the session; or, sending identification information of a session established by the third network for the terminal device to a third session management network element of the third network, and receiving identification information of the second session management network element corresponding to the session from the third session management network element; or, sending identification information of a session established by the third network for the terminal device to a second unified data management network element of the second network, and receiving identification information of the second session management network element corresponding to the session from the second unified data management network element; or, randomly determining identification information of the second session management network element according to a preset configuration.

[0029] Based on this possible design, the second mobility management network element can adopt any of the above methods to select a second session management network element that can assist the terminal device in network switching, so that the subsequent first session management network element obtains the context information of the terminal device stored in the third session management network element through the second session management network element selected by the second mobility management network element, thereby ensuring the service continuity of the terminal device during the switching process and improving communication performance.

[0030] In one possible design, the fourth request also includes first identification information and global identification information of the target access network device; wherein the first identification information is identification information allocated by the third network to the terminal device of the second network for accessing the third network, and the global identification information of the target access network device includes second identification information, and the second identification information is identification information allocated by the first network to the terminal device of the first network for accessing the first network.

[0031] In one possible design, when the first identification information and the second identification information indicate that the terminal device switches from the third network to the first network, a third request is sent to the first mobility management network element.

[0032] Based on the above two possible designs, according to the first identification information, the second mobility management network element can determine that the terminal device is a roaming user in a different network. According to the first identification information and the second identification information, the second mobility management network element can determine that the terminal device roaming in a different network switches from the third network to the first network. If the second mobility management network element supports the switching of the terminal device roaming in a different network from the third network to the first network, the second mobility management network element can send a third request to the first mobility management network element of the first network.

[0033] In one possible design, before sending a third request to the first mobility management network element of the first network, the method also includes: determining the first mobility management network element based on the second identification information; or, sending a service discovery request to the second topology management network element of the second network, receiving a service discovery response from the second topology management network element, and determining the first mobility management network element based on the service discovery response; wherein the service discovery request includes the global identification information of the target access network device, the service discovery request is used to request discovery of the mobility management network element associated with the target access network device, and the service discovery response includes the identification information of the first mobility management network element.

[0034] Based on this possible design, the second mobility management network element can adopt any of the above methods to select a suitable first mobility management network element for the terminal device to better provide network services for the terminal device and improve communication performance.

[0035] In one possible design, the third request includes third identification information, where the third identification information is identification information allocated by the first network to a terminal device of the second network for accessing the first network.

[0036] Based on this possible design, the second mobility management network element may determine the third identification information when determining to send the third request to the first mobility management network element, and send the third request to the first mobility management network element through the third identification information.

[0037] In one possible design, the fourth request also includes one or more of the following: network slice information, global identification information of the target access network device, and identification information of the third session management network element of the third network.

[0038] In one possible design, the third request also includes one or more of the following: network slice information, global identification information of the target access network device, and identification information of the third session management network element of the third network.

[0039] Based on the above two possible designs, by carrying network slice information, it is convenient for the network elements in the second network and the first network to determine the network elements participating in the network switching process (such as determining the second session management network element, the first session management network element, etc.) according to the network slice information, so as to better provide network services for the terminal device and improve communication performance. By carrying the global identification information of the target access network device, it is convenient for each network to determine the network to be switched by the terminal device, and it is also convenient for the network elements in the second network and the first network to determine the network elements participating in the network switching process (such as determining the second session management network element, the first mobility management network element, the first session management network element, etc.) according to the network slice information, so as to better provide network services for the terminal device and improve communication performance. By carrying the identification information of the third session management network element, it is convenient for the second session management network element to determine the corresponding third session management network element according to the identification information of the third session management network element, and then obtain the context information of the terminal device.

[0040] In one possible design, a third response is received from a first mobility management network element; wherein the third response is used to indicate that the first network allows the terminal device to switch from the third network to the first network, and the third response includes identification information of the first mobility management network element and the second tunnel information; and a fourth response is sent to the third mobility management network element; wherein the fourth response is used to indicate that the first network allows the terminal device to switch from the third network to the first network, and the fourth response includes identification information of the first mobility management network element and the second tunnel information.

[0041] In one possible design, the second tunnel information is used to establish an uplink data forwarding tunnel between a source access network device of a third network and a third user plane network element of the third network.

[0042] Based on the above two possible designs, by forwarding the second tunnel information, the source access network device can realize communication with the third user plane network element through the second tunnel information. This facilitates the subsequent establishment of a data forwarding tunnel between the source access network device, the third user plane network element, the second user plane network element, and the first user plane network element, and facilitates the subsequent source access network device to send the service data of the terminal device to the first user plane network element through the third user plane network element and the second user plane network element, thereby ensuring the service continuity of the terminal device during the switching process.

[0043] In a fourth aspect, an embodiment of the present application provides a network switching method, the execution subject of the method can be a second session management network element of a second network, or a chip, a chip system, or a system on chip of the second session management network element. The method includes: receiving a second request from a first session management network element of a first network; wherein the second request is used to request to obtain context information of a terminal device, and the second network is a home network of the terminal device; sending a fifth request to a third session management network element of a third network; wherein the third session management network element is a network element in the third network that establishes a session for the terminal device, and the fifth request is used to request to obtain context information of the terminal device; receiving a fifth response from the third session management network element; wherein the fifth response includes the context information of the terminal device stored in the third session management network element; sending a second response to the first session management network element; wherein the second response includes the context information of the terminal device stored in the third session management network element.

[0044] Based on the fourth aspect, when the terminal device needs to switch from the third network to the first network, the second session management network element of the terminal device's home network (i.e., the second network) can assist the first session management network element in obtaining the context information of the terminal device stored in the third session management network element, so that the second session management network element can establish a session for the terminal device based on the context information of the terminal device, realize the switching of the terminal device between different visited networks (i.e., realize the switching of the terminal device between the third network and the first network), and at the same time ensure the business continuity of the terminal device during the switching process and improve the communication performance.

[0045] In one possible design, the second request includes one or more of the following: identification information of the session established by the third network for the terminal device, and identification information of the third session management network element.

[0046] Based on this possible design, by carrying the identification information of the session established by the third network for the terminal device and / or the identification information of the third session management network element in the second request, the second session management network element can determine the corresponding third session management network element based on the identification information of the session or the identification information of the third session management network element, and then obtain the context information of the terminal device.

[0047] In one possible design, the second tunnel information and the third tunnel information are obtained; the first tunnel information and the fourth tunnel information are received from the second user plane network element of the second network; wherein the fifth response includes the second tunnel information and the third tunnel information, the first tunnel information is used to establish a data forwarding tunnel between the first user plane network element of the first network and the second user plane network element of the second network, and the third tunnel information and the fourth tunnel information are used to establish a data forwarding tunnel between the second user plane network element and the third user plane network element; the first tunnel information and the second tunnel information are sent to the first session management network element; the third tunnel information is sent to the second user plane network element; and the fourth tunnel information is sent to the third session management network element of the third network.

[0048] In one possible design, the second tunnel information is used to establish an uplink data forwarding tunnel between a source access network device of a third network and a third user plane network element of the third network.

[0049] Based on the above two possible designs, by forwarding the first tunnel information, it is convenient for the first user plane network element to communicate with the second user plane network element through the first tunnel information, and by forwarding the second tunnel information, it is convenient for the source access network device to communicate with the third user plane network element through the second tunnel information. By forwarding the third tunnel information and the fourth tunnel information, it is convenient for the second user plane network element to communicate with the third user plane network element. This facilitates the subsequent establishment of a data forwarding tunnel between the source access network device, the third user plane network element, the second user plane network element, and the first user plane network element, and facilitates the subsequent source access network device to send the service data of the terminal device to the first user plane network element through the third user plane network element and the second user plane network element, thereby ensuring the service continuity of the terminal device during the switching process.

[0050] In a fifth aspect, an embodiment of the present application provides a network switching method, the execution subject of the method can be a third mobility management network element of a third network, or a chip, a chip system or a system on chip of the third mobility management network element. The method includes: receiving a switching request from a terminal device; wherein the switching request includes the global identification information of the target access network device, and the switching request is used to request switching to the target access network device; according to the switching request, obtaining the identification information of the second session management network element of the second network; wherein the second network is the home network of the terminal device; sending a fourth request to the second mobility management network element of the second network; wherein the fourth request is used to request switching the terminal device from the third network to the first network, and the fourth request includes the identification information of the second session management network element.

[0051] Based on the fifth aspect, when the terminal device needs to switch from the third network to the first network, the second mobility management network element of the terminal device's home network (i.e., the second network) can assist the third mobility management network element of the third network to pass the terminal device's switching request to the first network. By carrying the identification information of the second session management network element in the fourth request, the first session management network element of the first network can request the context information of the terminal device from the second session management network element, and then establish a session for the terminal device, thereby realizing the switching of the terminal device between the third network and the first network, while ensuring the business continuity of the terminal device during the switching process and improving communication performance.

[0052] In one possible design, obtaining identification information of a second session management network element of a second network includes: determining identification information of the second session management network element from an association relationship between identification information of a session pre-stored and identification information of the second session management network element according to identification information of a session established by a third network for a terminal device; or, sending identification information of a session established by the third network for a terminal device to a third session management network element of a third network, and receiving identification information of the second session management network element from the third session management network element; or, sending identification information of a session established by the third network for a terminal device to a unified data management network element, and receiving identification information of the second session management network element from the unified data management network element; wherein the unified data management network element is a third unified data management network element of the third network, or the unified data management network element is a second unified data management network element of the second network.

[0053] Based on this possible design, the third mobility management network element can adopt any of the above methods to select a second session management network element that can assist the terminal device in network switching, so that the first session management network element obtains the context information of the terminal device stored in the third session management network element through the second session management network element selected by the third mobility management network element, thereby ensuring the service continuity of the terminal device during the switching process and improving communication performance.

[0054] In one possible design, the fourth request also includes first identification information and global identification information of the target access network device; wherein the first identification information is identification information allocated by the third network to the terminal device of the second network for accessing the third network, and the global identification information of the target access network device includes second identification information, and the second identification information is identification information allocated by the first network to the terminal device of the first network for accessing the first network.

[0055] Based on this possible design, by carrying the first identification information and the global identification information of the target access network device in the fourth request, the second mobility management network element can forward the network switching request of the terminal device to the first mobility management network element of the first network when it determines that the terminal device belonging to roaming in a different network requests to switch from the third network to the first network.

[0056] In one possible design, a fourth response is received from a second mobility management network element; wherein the fourth response is used to indicate that the first network allows the terminal device to switch from the third network to the first network, and the fourth response includes identification information of the first mobility management network element of the first network and second tunnel information, and the second tunnel information is used for a source access network device of the third network to establish an uplink data forwarding tunnel with a third user plane network element of the third network; and the second tunnel information is sent to the source access network device of the terminal device.

[0057] Based on this possible design, by forwarding the second tunnel information, the source access network device can facilitate communication with the third user plane network element through the second tunnel information. This facilitates the subsequent establishment of a data forwarding tunnel between the source access network device, the third user plane network element, the second user plane network element, and the first user plane network element, and facilitates the subsequent source access network device to send the service data of the terminal device to the first user plane network element through the third user plane network element and the second user plane network element, thereby ensuring the service continuity of the terminal device during the switching process.

[0058] In a sixth aspect, an embodiment of the present application provides a network switching method, the execution subject of the method can be a second user plane network element of a second network, or a chip, a chip system, or a system on chip of the second user plane network element. The method includes: receiving service data of a terminal device from a third user plane network element of a third network; wherein the second network is a home network of the terminal device; determining a first user plane network element of a first network according to the service data of the terminal device; and sending the service data of the terminal device to the first user plane network element of the first network.

[0059] Based on the sixth aspect, when the terminal device needs to switch from the third network to the first network, the second user plane network element of the terminal device's home network (i.e., the second network) can assist the first user plane network element to obtain the service data of the terminal device sent by the source access network device to the third user plane network element, while realizing the switching of the terminal device between different visited networks (i.e., realizing the switching of the terminal device between the third network and the first network), it ensures the service continuity of the terminal device during the switching process and improves the communication performance.

[0060] In one possible design, service data of a terminal device from a third user plane network element of a third network is received, including: sending fourth tunnel information to a second session management network element of a second network; wherein the fourth tunnel information is used to establish an uplink data forwarding tunnel between the second user plane network element and the third user plane network element; and receiving service data of the terminal device sent by the third user plane network element according to the fourth tunnel information.

[0061] In one possible design, the service data of the terminal device is sent to the first user plane network element of the first network, including: receiving fifth tunnel information from the second session management network element of the second network; wherein the fifth tunnel information is used to establish an uplink data forwarding tunnel between the first user plane network element and the second user plane network element; and sending the service data of the terminal device to the first user plane network element according to the fifth tunnel information.

[0062] Based on the above two possible designs, the second user plane network element can forward the service data of the terminal device according to the tunnel information, ensure the service continuity of the terminal device during the switching process, and improve the communication performance.

[0063] In the seventh aspect, an embodiment of the present application provides a communication device, which can be applied to the first session management network element of the first network of the first aspect above to implement the functions performed by the first session management network element above. The communication device can be the first session management network element, or it can be a chip or chip system or system on chip of the first session management network element, etc. The communication device can perform the functions performed by the first session management network element through hardware, or it can perform the corresponding software implementation through hardware. The hardware or software includes one or more modules corresponding to the above functions. For example, a transceiver module and a processing module. The transceiver module can independently complete the following transceiver operations, or it can cooperate with the processing module to complete the following transceiver operations; accordingly, the processing module can also independently complete the following processing operations, or it can cooperate with the transceiver module to complete the following processing operations, without limitation.

[0064] Among them, the transceiver module is used to receive a first request from a first mobility management network element of a first network, the first request is used to request to establish a session for a terminal device, the first request includes identification information of a second session management network element of a second network, and the second network is a home network of the terminal device; the transceiver module is also used to send a second request to the second session management network element and receive a second response from the second session management network element, and the processing module is used to establish a session for the terminal device according to the second response; wherein the second request is used to request to obtain context information of the terminal device, the second response includes the context information of the terminal device stored in a third session management network element, and the third session management network element is a network element in a third network that establishes a session for the terminal device.

[0065] In one possible design, the first request also includes one or more of the following: identification information of the session established by the third network for the terminal device, and identification information of the third session management network element.

[0066] In one possible design, the second request includes one or more of the following: identification information of the session established by the third network for the terminal device, and identification information of the third session management network element.

[0067] In one possible design, the processing module is specifically used to obtain the first tunnel information and the second tunnel information, and the transceiver module is also used to send the first tunnel information to the first user plane network element and send a first response to the first mobility management network element; wherein the first response includes the first tunnel information and the second tunnel information, the first response includes the second tunnel information, and the first tunnel information is used to establish a data forwarding tunnel between the first user plane network element of the first network and the second user plane network element of the second network.

[0068] In one possible design, the second tunnel information is used to establish an uplink data forwarding tunnel between a source access network device of a third network and a third user plane network element of the third network.

[0069] Among them, the technical effects brought about by the above-mentioned seventh aspect or any possible design in the seventh aspect can refer to the technical effects brought about by the above-mentioned first aspect or any possible design in the first aspect, and will not be repeated here.

[0070] In an eighth aspect, an embodiment of the present application provides a communication device, which can be applied to the first mobility management network element of the first network of the second aspect to implement the functions performed by the first mobility management network element. The communication device can be the first mobility management network element, or it can be a chip or chip system or system on chip of the first mobility management network element, etc. The communication device can execute the functions performed by the first mobility management network element through hardware, or it can execute the corresponding software implementation through hardware. The hardware or software includes one or more modules corresponding to the above functions. For example, a transceiver module and a processing module. The transceiver module can independently complete the following transceiver operations, or it can cooperate with the processing module to complete the following transceiver operations; accordingly, the processing module can also independently complete the following processing operations, or it can cooperate with the transceiver module to complete the following processing operations, without limitation.

[0071] Among them, the transceiver module is used to receive a third request from a second mobility management network element of the second network; the third request is used to request to switch the terminal device from the third network to the first network, and the second network is the home network of the terminal device; the processing module is used to obtain the identification information of the second session management network element of the second network; the transceiver module is also used to send a first request to the first session management network element of the first network; wherein the first request is used to request to establish a session for the terminal device, and the first request includes the identification information of the second session management network element.

[0072] In one possible design, the processing module is specifically used to: determine the identification information of the second session management network element according to the third request; wherein the third request includes the identification information of the second session management network element; or, the third request includes network slice information, and the identification information of the second session management network element is determined according to the network slice information; or, according to a preset configuration, randomly determine the identification information of the second session management network element.

[0073] In one possible design, the third request includes global identification information of the target access network device, and the processing module is further used to determine the first session management network element based on the global identification information of the target access network device before the transceiver module sends the first request to the first session management network element of the first network; or, the third request includes network slice information, and the processing module is further used to determine the first session management network element based on the network slice information before the transceiver module sends the first request to the first session management network element of the first network.

[0074] In one possible design, the third request also includes one or more of the following: identification information of the session established by the third network for the terminal device, and identification information of the third session management network element of the third network.

[0075] In one possible design, the first request also includes one or more of the following: identification information of the session established by the third network for the terminal device, and identification information of a third session management network element of the third network.

[0076] In one possible design, the transceiver module is also used to receive a first response from the first session management network element, and send a third response to the second mobility management network element; wherein the first response includes the second tunnel information; the third response is used to indicate that the first network allows the terminal device to switch from the third network to the first network, and the third response includes the identification information of the first mobility management network element and the second tunnel information.

[0077] In one possible design, the second tunnel information is used to establish an uplink data forwarding tunnel between a source access network device of a third network and a third user plane network element of the third network.

[0078] Among them, the technical effects brought about by the above-mentioned eighth aspect or any possible design in the eighth aspect can refer to the technical effects brought about by the above-mentioned second aspect or any possible design in the second aspect, and will not be repeated here.

[0079] In the ninth aspect, an embodiment of the present application provides a communication device, which can be applied to the second mobility management network element of the second network of the third aspect to implement the functions performed by the second mobility management network element. The communication device can be the second mobility management network element, or it can be a chip or chip system or system on chip of the second mobility management network element, etc. The communication device can execute the functions performed by the second mobility management network element through hardware, or it can execute the corresponding software implementation through hardware. The hardware or software includes one or more modules corresponding to the above functions. For example, a transceiver module and a processing module. The transceiver module can independently complete the following transceiver operations, or it can cooperate with the processing module to complete the following transceiver operations; accordingly, the processing module can also independently complete the following processing operations, or it can cooperate with the transceiver module to complete the following processing operations, without limitation.

[0080] Among them, the transceiver module is used to receive a fourth request from a third mobility management network element of a third network; wherein the fourth request is used to request to switch the terminal device from the third network to the first network, and the second network is the home network of the terminal device; the processing module is used to obtain the identification information of the second session management network element of the second network; the transceiver module is also used to send a third request to the first mobility management network element of the first network; wherein the third request is used to request to switch the terminal device from the third network to the first network, and the third request includes the identification information of the second session management network element.

[0081] In a possible design, the processing module is specifically used to determine the identification information of the second session management network element according to the fourth request; wherein the fourth request includes the identification information of the second session management network element. Alternatively, the fourth request includes the identification information of the session established by the third network for the terminal device, and the processing module is specifically used to determine the identification information of the second session management network element from the association relationship between the pre-stored identification information of the session and the identification information of the second session management network element according to the identification information of the session. Alternatively, the transceiver module is also used to send the identification information of the session established by the third network for the terminal device to the third session management network element of the third network, and receive the identification information of the second session management network element corresponding to the session from the third session management network element. Alternatively, the transceiver module is also used to send the identification information of the session established by the third network for the terminal device to the second unified data management network element of the second network, and receive the identification information of the second session management network element corresponding to the session from the second unified data management network element. Alternatively, the processing module is specifically used to randomly determine the identification information of the second session management network element according to a preset configuration.

[0082] In one possible design, the fourth request also includes first identification information and global identification information of the target access network device; wherein the first identification information is identification information allocated by the third network to the terminal device of the second network for accessing the third network, and the global identification information of the target access network device includes second identification information, and the second identification information is identification information allocated by the first network to the terminal device of the first network for accessing the first network.

[0083] In one possible design, the transceiver module is specifically used to send a third request to the first mobility management network element when the first identification information and the second identification information indicate that the terminal device switches from the third network to the first network.

[0084] In one possible design, before the transceiver module sends the third request to the first mobility management network element of the first network: the processing module is also used to determine the first mobility management network element based on the second identification information; or, the transceiver module is also used to send a service discovery request to the second topology management network element of the second network, and receive a service discovery response from the second topology management network element, and the processing module determines the first mobility management network element based on the service discovery response; wherein the service discovery request includes the global identification information of the target access network device, the service discovery request is used to request to discover the mobility management network element associated with the target access network device, and the service discovery response includes the identification information of the first mobility management network element.

[0085] In one possible design, the third request includes third identification information, where the third identification information is identification information allocated by the first network to a terminal device of the second network for accessing the first network.

[0086] In one possible design, the fourth request also includes one or more of the following: network slice information, global identification information of the target access network device, and identification information of the third session management network element of the third network.

[0087] In one possible design, the third request also includes one or more of the following: network slice information, global identification information of the target access network device, and identification information of the third session management network element of the third network.

[0088] In one possible design, the transceiver module is also used to receive a third response from the first mobility management network element; wherein the third response is used to indicate that the first network allows the terminal device to switch from the third network to the first network, and the third response includes the identification information of the first mobility management network element and the second tunnel information; the transceiver module is also used to send a fourth response to the third mobility management network element; wherein the fourth response is used to indicate that the first network allows the terminal device to switch from the third network to the first network, and the fourth response includes the identification information of the first mobility management network element and the second tunnel information.

[0089] In one possible design, the second tunnel information is used to establish an uplink data forwarding tunnel between a source access network device of a third network and a third user plane network element of the third network.

[0090] Among them, the technical effects brought about by the above-mentioned ninth aspect or any possible design in the ninth aspect can refer to the technical effects brought about by the above-mentioned third aspect or any possible design in the third aspect, and will not be repeated here.

[0091] In the tenth aspect, an embodiment of the present application provides a communication device, which can be applied to the second session management network element of the second network of the fourth aspect to implement the functions performed by the second session management network element. The communication device can be the second session management network element, or it can be a chip or chip system or system on chip of the second session management network element, etc. The communication device can perform the functions performed by the second session management network element through hardware, or it can perform the corresponding software implementation through hardware. The hardware or software includes one or more modules corresponding to the above functions. For example, a transceiver module and a processing module. The transceiver module can independently complete the following transceiver operations, or it can cooperate with the processing module to complete the following transceiver operations; accordingly, the processing module can also independently complete the following processing operations, or it can cooperate with the transceiver module to complete the following processing operations, without limitation.

[0092] Among them, the transceiver module is used to receive a second request from a first session management network element of a first network; wherein the second request is used to request to obtain context information of a terminal device, and the second network is a home network of the terminal device; the transceiver module is also used to send a fifth request to a third session management network element of a third network; wherein the third session management network element is a network element in the third network that establishes a session for the terminal device, and the fifth request is used to request to obtain context information of the terminal device; the transceiver module is also used to receive a fifth response from the third session management network element; wherein the fifth response includes the context information of the terminal device stored in the third session management network element; the transceiver module is also used to send a second response to the first session management network element; wherein the second response includes the context information of the terminal device stored in the third session management network element.

[0093] In one possible design, the second request includes one or more of the following: identification information of the session established by the third network for the terminal device, and identification information of the third session management network element.

[0094] In one possible design, the processing module is used to obtain the second tunnel information and the third tunnel information; the transceiver module is used to receive the first tunnel information and the fourth tunnel information from the second user plane network element of the second network; wherein the fifth response includes the second tunnel information and the third tunnel information, the first tunnel information is used to establish a data forwarding tunnel between the first user plane network element of the first network and the second user plane network element of the second network, and the third tunnel information and the fourth tunnel information are used to establish a data forwarding tunnel between the second user plane network element and the third user plane network element; the transceiver module is also used to send the first tunnel information and the second tunnel information to the first session management network element, send the third tunnel information to the second user plane network element, and send the fourth tunnel information to the third session management network element of the third network.

[0095] In one possible design, the second tunnel information is used to establish an uplink data forwarding tunnel between a source access network device of a third network and a third user plane network element of the third network.

[0096] Among them, the technical effects brought about by the above-mentioned tenth aspect or any possible design in the tenth aspect can refer to the technical effects brought about by the above-mentioned fourth aspect or any possible design in the fourth aspect, and will not be repeated here.

[0097] In the eleventh aspect, an embodiment of the present application provides a communication device, which can be applied to the third mobility management network element of the third network of the fifth aspect to implement the functions performed by the third mobility management network element. The communication device can be a third mobility management network element, or a chip or chip system or system on chip of the third mobility management network element, etc. The communication device can execute the functions performed by the third mobility management network element through hardware, or can execute the corresponding software implementation through hardware. The hardware or software includes one or more modules corresponding to the above functions. For example, a transceiver module and a processing module. The transceiver module can independently complete the following transceiver operations, or cooperate with the processing module to complete the following transceiver operations; accordingly, the processing module can also independently complete the following processing operations, or cooperate with the transceiver module to complete the following processing operations, without limitation.

[0098] Among them, the transceiver module is used to receive a switching request from a terminal device; wherein the switching request includes the global identification information of the target access network device, and the switching request is used to request switching to the target access network device; the processing module is used to obtain the identification information of the second session management network element of the second network according to the switching request; wherein the second network is the home network of the terminal device; the transceiver module is also used to send a fourth request to the second mobility management network element of the second network; wherein the fourth request is used to request switching the terminal device from the third network to the first network, and the fourth request includes the identification information of the second session management network element.

[0099] In one possible design, the processing module is specifically used to determine the identification information of the second session management network element from the association relationship between the pre-stored identification information of the session and the identification information of the second session management network element according to the identification information of the session established by the third network for the terminal device; or, the transceiver module is also used to send the identification information of the session established by the third network for the terminal device to the third session management network element of the third network, and receive the identification information of the second session management network element from the third session management network element; or, the transceiver module is also used to send the identification information of the session established by the third network for the terminal device to the unified data management network element, and receive the identification information of the second session management network element from the unified data management network element; wherein the unified data management network element is the third unified data management network element of the third network, or the unified data management network element is the second unified data management network element of the second network.

[0100] In one possible design, the fourth request also includes first identification information and global identification information of the target access network device; wherein the first identification information is identification information allocated by the third network to the terminal device of the second network for accessing the third network, and the global identification information of the target access network device includes second identification information, and the second identification information is identification information allocated by the first network to the terminal device of the first network for accessing the first network.

[0101] In one possible design, the transceiver module is also used to receive a fourth response from the second mobility management network element; wherein the fourth response is used to indicate that the first network allows the terminal device to switch from the third network to the first network, and the fourth response includes identification information of the first mobility management network element of the first network and second tunnel information, and the second tunnel information is used to establish an uplink data forwarding tunnel between the source access network device of the third network and the third user plane network element of the third network; the transceiver module is also used to send the second tunnel information to the source access network device of the terminal device.

[0102] Among them, the technical effects brought about by the above-mentioned eleventh aspect or any possible design in the eleventh aspect can refer to the technical effects brought about by the above-mentioned fifth aspect or any possible design in the fifth aspect, and no further details will be given.

[0103] In the twelfth aspect, an embodiment of the present application provides a communication device, which can be applied to the second user plane network element of the second network of the sixth aspect to implement the functions performed by the second user plane network element. The communication device can be the second user plane network element, or it can be a chip or chip system or system on chip of the second user plane network element, etc. The communication device can execute the functions performed by the second user plane network element through hardware, or it can execute the corresponding software implementation through hardware. The hardware or software includes one or more modules corresponding to the above functions. For example, a transceiver module and a processing module. The transceiver module can independently complete the following transceiver operations, or it can cooperate with the processing module to complete the following transceiver operations; accordingly, the processing module can also independently complete the following processing operations, or it can cooperate with the transceiver module to complete the following processing operations, without limitation.

[0104] Among them, the transceiver module is used to receive the service data of the terminal device from the third user plane network element of the third network; wherein the second network is the home network of the terminal device; the processing module is used to determine the first user plane network element of the first network according to the service data of the terminal device; the transceiver module is also used to send the service data of the terminal device to the first user plane network element of the first network.

[0105] In one possible design, the transceiver module is also used to send fourth tunnel information to the second session management network element of the second network; wherein the fourth tunnel information is used to establish an uplink data forwarding tunnel between the second user plane network element and the third user plane network element; the transceiver module is also used to receive service data of the terminal device sent by the third user plane network element according to the fourth tunnel information.

[0106] In one possible design, the transceiver module is also used to receive the fifth tunnel information from the second session management network element of the second network; wherein the fifth tunnel information is used to establish an uplink data forwarding tunnel between the first user plane network element and the second user plane network element; the transceiver module is also used to send the service data of the terminal device to the first user plane network element according to the fifth tunnel information.

[0107] Among them, the technical effects brought about by the above-mentioned twelfth aspect or any possible design in the twelfth aspect can refer to the technical effects brought about by the above-mentioned sixth aspect or any possible design in the sixth aspect, and no further details will be given.

[0108] In the thirteenth aspect, an embodiment of the present application provides a communication device, which includes one or more processors; one or more processors are used to run computer programs or instructions. When the one or more processors execute the computer instructions or instructions, the communication device executes the network switching method as described in the first aspect or any possible design of the first aspect, or executes the network switching method as described in the second aspect or any possible design of the second aspect, or executes the network switching method as described in the third aspect or any possible design of the third aspect, or executes the network switching method as described in the fourth aspect or any possible design of the fourth aspect, or executes the network switching method as described in the fifth aspect or any possible design of the fifth aspect, or executes the network switching method as described in the sixth aspect or any possible design of the sixth aspect.

[0109] In one possible design, the communication device further includes one or more memories, one or more memories are coupled to one or more processors, and the one or more memories are used to store the above-mentioned computer programs or instructions. In one possible implementation, the memory is located outside the communication device. In another possible implementation, the memory is located inside the communication device. In an embodiment of the present application, the processor and the memory may also be integrated into one device, that is, the processor and the memory may also be integrated together. In one possible implementation, the communication device further includes a transceiver, and the transceiver is used to receive information and / or send information.

[0110] In one possible design, the communication device also includes one or more communication interfaces, the one or more communication interfaces are coupled to the one or more processors, and the one or more communication interfaces are used to communicate with other modules outside the communication device.

[0111] In the fourteenth aspect, an embodiment of the present application provides a communication device, which includes an input and output interface and a logic circuit; the input and output interface is used to input and / or output information; the logic circuit is used to execute the network switching method described in the first aspect or any possible design of the first aspect, or execute the network switching method described in the second aspect or any possible design of the second aspect, or execute the method described in the third aspect or any possible design of the third aspect, or execute the network switching method described in the fourth aspect or any possible design of the fourth aspect, or execute the network switching method described in the fifth aspect or any possible design of the fifth aspect, or execute the network switching method described in the sixth aspect or any possible design of the sixth aspect, and process and / or generate information according to the information.

[0112] In the fifteenth aspect, an embodiment of the present application provides a computer-readable storage medium, which stores computer instructions or programs. When the computer instructions or programs are run on a computer, the network switching method as described in the first aspect or any possible design of the first aspect is executed, or the network switching method as described in the second aspect or any possible design of the second aspect is executed, or the network switching method as described in the third aspect or any possible design of the third aspect is executed, or the network switching method as described in the fourth aspect or any possible design of the fourth aspect is executed, or the network switching method as described in the fifth aspect or any possible design of the fifth aspect is executed, or the network switching method as described in the sixth aspect or any possible design of the sixth aspect is executed.

[0113] In the sixteenth aspect, an embodiment of the present application provides a computer program product comprising computer instructions, which, when executed on a computer, causes the network switching method as described in the first aspect or any possible design of the first aspect to be executed, or causes the network switching method as described in the second aspect or any possible design of the second aspect to be executed, or causes the network switching method as described in the third aspect or any possible design of the third aspect to be executed, or causes the network switching method as described in the fourth aspect or any possible design of the fourth aspect to be executed, or causes the network switching method as described in the fifth aspect or any possible design of the fifth aspect to be executed, or causes the network switching method as described in the sixth aspect or any possible design of the sixth aspect to be executed.

[0114] In the seventeenth aspect, an embodiment of the present application provides a computer program, which, when running on a computer, causes the network switching method as described in the first aspect or any possible design of the first aspect to be executed, or causes the network switching method as described in the second aspect or any possible design of the second aspect to be executed, or causes the network switching method as described in the third aspect or any possible design of the third aspect to be executed, or causes the network switching method as described in the fourth aspect or any possible design of the fourth aspect to be executed, or causes the network switching method as described in the fifth aspect or any possible design of the fifth aspect to be executed, or causes the network switching method as described in the sixth aspect or any possible design of the sixth aspect to be executed.

[0115] In the eighteenth aspect, an embodiment of the present application provides a chip, including: a processor, the processor is coupled to a memory, the memory is used to store programs or instructions, when the program or instructions are executed by the processor, the chip executes the network switching method described in the first aspect or any possible design of the first aspect, or executes the network switching method described in the second aspect or any possible design of the second aspect, or executes the network switching method described in the third aspect or any possible design of the third aspect, or executes the network switching method described in the fourth aspect or any possible design of the fourth aspect, or executes the network switching method described in the fifth aspect or any possible design of the fifth aspect, or executes the network switching method described in the sixth aspect or any possible design of the sixth aspect.

[0116] Among them, the technical effects brought about by any design method from the thirteenth to the eighteenth aspects can refer to the technical effects brought about by the above-mentioned first aspect or any possible design in the first aspect, or refer to the technical effects brought about by the above-mentioned second aspect or any possible design in the second aspect, or refer to the technical effects brought about by the above-mentioned third aspect or any possible design in the third aspect, or refer to the technical effects brought about by the above-mentioned fourth aspect or any possible design in the fourth aspect, or refer to the technical effects brought about by the above-mentioned fifth aspect or any possible design in the fifth aspect, or refer to the technical effects brought about by the above-mentioned sixth aspect or any possible design in the sixth aspect.

[0117] In the nineteenth aspect, an embodiment of the present application provides a communication system, which may include the communication device described in the seventh aspect or any possible design of the seventh aspect, the communication device described in the eighth aspect or any possible design of the eighth aspect, the communication device described in the ninth aspect or any possible design of the ninth aspect, the communication device described in the tenth aspect or any possible design of the tenth aspect, and the communication device described in the eleventh aspect or any possible design of the eleventh aspect, or may also include the communication device described in the twelfth aspect or any possible design of the twelfth aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0118] Figure 1 A schematic diagram of a network sharing research content provided in an embodiment of the present application;

[0119] Figure 2 A schematic diagram of a network sharing provided in an embodiment of the present application;

[0120] Figure 3 A schematic diagram of a network switching based on roaming in a different network provided in an embodiment of the present application;

[0121] Figure 4 A schematic diagram of a communication system provided in an embodiment of the present application;

[0122] Figure 5 A schematic diagram of a 5G communication system provided in an embodiment of the present application;

[0123] Figure 6 A diagram showing the structure of a communication device provided in an embodiment of the present application;

[0124] Figure 7 A flowchart of a network switching method provided in an embodiment of the present application;

[0125] Figure 8 A flowchart of a process for establishing a data forwarding tunnel provided in an embodiment of the present application;

[0126] Fig. 9 A schematic diagram of forwarding service data of a terminal device provided in an embodiment of the present application;

[0127] Fig.10 A flowchart of a network switching method provided in an embodiment of the present application;

[0128] Fig.11 A flowchart of a network switching method provided in an embodiment of the present application;

[0129] Fig.12 A flowchart of a network switching method provided in an embodiment of the present application;

[0130] Fig.13 A flowchart of a network switching method provided in an embodiment of the present application;

[0131] Fig.14 A flowchart of a network switching method provided in an embodiment of the present application;

[0132] Fig.15 A schematic diagram of a communication device provided in an embodiment of the present application;

[0133] Fig.16 A structural diagram of a communication device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0134] Before describing the embodiments of the present application, the technical terms involved in the embodiments of the present application are described.

[0135] Network sharing: When deploying access networks and core networks, the shared access network is allowed to access different core networks respectively. This is a way for operators to share access network resources. Network sharing enables operators to maximize network deployment, improve overall network quality, and reduce network deployment costs.

[0136] The third generation partnership project (3GPP) communication system has supported different types of network sharing since Rel-5, most of which are inherited by the fifth-generation (5G) mobile communication system (Rel-15 and later). 3GPP TS 23.251 allows shared access networks to be connected to different operator core networks respectively, and operators can share not only radio network elements but also radio resources themselves. As 5G deployment expands, more network sharing scenarios may emerge based on the strategies of different operators, business agreements, and specific rules / legislation in different countries.

[0137] As network sharing continues to develop, one of the challenges facing operators is maintaining the interconnection between the shared access network and the core network of operators participating in network sharing (i.e., the core network participating in network sharing) (e.g., the number of network interfaces that need to be maintained is large), especially when there are a large number of shared access network devices, the network deployment and operation costs are high. Therefore, it is necessary to study other network sharing scenarios, such as studying the scenario where there is no direct connection between the shared access network and the core network of operators participating in network sharing, in order to reduce network deployment and operation costs.

[0138] For example, refer to Figure 1 The network sharing research content shown in the figure mainly includes the following business requirements: network sharing is transparent to users, that is, the user's terminal device only displays the name of the contracted operator, and the service provider of the terminal device is its contracted operator; supports mobility management between core networks participating in network sharing; supports business continuity and quality of service (QoS) between core networks participating in network sharing; supports international roaming based on network sharing; security requirements; billing requirements; user / service experience; regulatory requirements; emergency services; public warning system (PWS) support and other requirements.

[0139] Based on this, it is proposed that the shared access network can directly access the core network 1 (ie, direct connection), and can also access the core network 2 through the core network 1 (ie, indirect connection).

[0140] For example, Figure 2As shown, operator (operator, OP) 1 deploys a wireless access network, which can be shared with the core networks of other operators (such as OP2, OP3, and OP4) under specific conditions. The shared access network can be directly connected to the core networks participating in network sharing, such as the shared access network can be directly connected to the core network of OP1, and the shared access network can also be directly connected to the core network of OP4. The shared access network can also be indirectly connected to the core networks participating in network sharing, such as the shared access network can be indirectly connected to the core network of OP2 through the core network of OP1, and the shared access network can also be indirectly connected to the core network of OP3 through the core network of OP1.

[0141] Among them, specific conditions may refer to a specific 5G frequency band or a specific area, etc., without restriction.

[0142] The shared access network device may access the core network of OP1 and the core network of OP4 in a multi-operator core network (MOCN) manner.

[0143] Based on the above network sharing, terminal devices of OP1 (such as UE1), terminal devices of OP2 (such as UE2), terminal devices of OP3 (such as UE3), and terminal devices of OP4 (such as UE4) can all access the shared access network of OP1, and terminal devices of OP2 and OP3 can be indirectly routed back to their core network through the core network of OP1 (such as UE2 is indirectly routed back to the core network of OP2 through the core network of OP1, and UE3 is indirectly routed back to the core network of OP3 through the core network of OP1) to achieve network access.

[0144] Among them, the operator name displayed on the terminal device of OP1 is the name of OP1. The operator name displayed on the terminal device of OP2 is the name of OP2, and the terminal device of OP2 is not aware of the core network of OP1. The operator name displayed on the terminal device of OP3 is the name of OP3, and the terminal device of OP3 is not aware of the core network of OP1. The operator name displayed on the terminal device of OP4 is the name of OP4.

[0145] Network switching based on cross-network roaming: When the terminal device moves out of the coverage of the home network, the terminal device can access the home network through the visited network based on the shared access network device. When the terminal device moves into the coverage of the home network, the terminal device can switch from the shared access network device to the access network device of the home network and access the home network through the access network device of the home network.

[0146] For example, refer to Figure 3 The visited network and the home network shown in the figure can be switched from the shared access network device to the access network device of the home network according to the following steps:

[0147] Step 1: The terminal device sends a handover request to the mobility management network element of the visited network. Correspondingly, the mobility management network element of the visited network receives the handover request from the terminal device.

[0148] The switching request may be used to request switching to a target access network device. The switching request may include global identification information of the target access network device. The target access network device may be an access network device of a home network of the terminal device.

[0149] The global identification information of the target access network device may include a public land mobile network (PLMN) to which the target access network device belongs and identification information of the target access network device in the PLMN.

[0150] Optionally, the switching request may also include global identification information of the terminal device.

[0151] The global identification information of the terminal device may include the PLMN to which the terminal device belongs and the identification information of the terminal device in the PLMN.

[0152] Exemplarily, the global identification information of the terminal device may be a subscription permanent identifier (SUPI) of the terminal device.

[0153] Step 2: The mobility management network element of the visited network sends a handover request to the mobility management network element of the home network. Correspondingly, the mobility management network element of the home network receives the handover request from the mobility management network element of the visited network.

[0154] Among them, the mobility management network element of the visited network can determine the PLMN to which the terminal device belongs based on the global identification information of the terminal device, and determine the PLMN to which the target access network device belongs based on the global identification information of the target access network device. When the PLMN to which the target access network device belongs is the same as the PLMN to which the terminal device belongs, it can be determined that the terminal device needs to switch to the home network, and then send a switching request to the mobility management network element of the home network.

[0155] Step 3: The mobility management network element of the home network interacts with other network elements on the home network side according to the handover request to establish a session for the terminal device.

[0156] Among them, the session management network element of the home network can implement session establishment of the terminal device by interacting with the mobility management network element of the home network and the user plane network element of the home network.

[0157] Step 4: The session management network element of the home network and the session management network element of the visited network establish a session for the terminal device.

[0158] Among them, the session management network element of the home network and the session management network element of the visited network can exchange tunnel information allocated by the user plane network element of the home network and the tunnel information allocated by the user plane network element of the visited network to achieve communication between the user plane network element of the home network and the user plane network element of the visited network.

[0159] Optionally, the session management network element of the home network may also acquire the context information of the terminal device by interacting with the session management network element of the visited network.

[0160] Step 5: The session management network element of the home network sends a session establishment completion response to the mobility management network element of the home network. Correspondingly, the mobility management network element of the home network receives the session establishment completion response from the session management network element of the home network.

[0161] Step 6: The mobility management network element of the home network sends a handover completion response to the mobility management network element of the visited network. Correspondingly, the mobility management network element of the visited network receives the handover completion response from the mobility management network element of the home network.

[0162] Step 7: The mobility management network element of the visited network may notify the terminal device to perform switching through the shared access network device.

[0163] Step 8: The terminal device switches to the target access network device.

[0164] The above-mentioned network switching based on roaming on different networks only supports switching between shared access network devices and access network devices of the home network. When the terminal device needs to switch from accessing the home network through visited network 1 to accessing the home network through visited network 2 during the movement, if there is no connection between visited network 1 and visited network 2, how the terminal device can switch from visited network 1 to visited network 2 while ensuring the business continuity of the terminal device during the switching process becomes a technical problem that needs to be solved urgently.

[0165] In order to solve the above technical problems, an embodiment of the present application provides a network switching method, in which a first session management network element of a first network can receive a first request from a first mobility management network element of the first network, where the first request is used to request to establish a session for a terminal device, and the first request may include identification information of a second session management network element of a second network, where the second network is a home network of the terminal device; a second request for requesting to obtain context information of the terminal device is sent to the second session management network element, a second response from the second session management network element is received, and a session is established for the terminal device based on the second response; wherein the second response includes the context information of the terminal device stored in a third session management network element, and the third session management network element is a network element in the third network that establishes a session for the terminal device.

[0166] In an embodiment of the present application, when a terminal device needs to switch from a third network to a first network, the second session management network element of the terminal device's home network (i.e., the second network) can assist the first session management network element in obtaining the context information of the terminal device stored in the third session management network element. Then, the second session management network element can establish a session for the terminal device based on the context information of the terminal device, thereby realizing the switching of the terminal device between different visited networks (i.e., realizing the switching of the terminal device between the third network and the first network), while ensuring the business continuity of the terminal device during the switching process and improving the communication performance.

[0167] The implementation of the embodiments of the present application will be described in detail below in conjunction with the accompanying drawings.

[0168] The network switching method provided in the embodiment of the present application can be used in any communication system, which communication system can be a 3GPP communication system, for example, a long term evolution (LTE) system, or a 5G mobile communication system, a new radio (NR) communication system, a new radio vehicle to everything (NR V2X) system, and can also be applied to a system of LTE and 5G hybrid networking, or a non-terrestrial network (NTN) system, a device-to-device (D2D) communication system, a machine-to-machine (M2M) communication system, an Internet of Things (IoT), and other next-generation communication systems, such as future communication systems such as 6G, and can also be a non-3GPP communication system without limitation.

[0169] Below Figure 4 Take the communication system provided in the embodiment of the present application as an example to describe.

[0170] Figure 4 A schematic diagram of a communication system provided in an embodiment of the present application is shown in FIG. Figure 4 As shown, the communication system may include a first network, a second network and a third network, and each network may include an access network device and a core network device.

[0171] Among them, taking the second network as the home network of the terminal device as an example, when the terminal device is located within the coverage of the second network, the terminal device can access the core network of the second network through the access network device in the second network. When the terminal device is located within the coverage of the first network, the terminal device can access the core network of the second network through the shared access network device in the first network through the core network of the first network. When the terminal device is located within the coverage of the third network, the terminal device can access the core network of the second network through the shared access network device of the third network through the core network of the third network. The terminal device can also switch between the access network device of the first network, the access network device of the second network, and the access network device of the third network.

[0172] in, Figure 4 The terminal device can be located within the beam / cell coverage of the access network device, and the access network device can provide communication services for the terminal device.

[0173] in, Figure 4 The terminal device in the term "terminal device" may be a device with wireless transceiver functions or a chip or chip system that can be set in the device, which can allow users to access the network and is a device used to provide voice and / or data connectivity to users. The terminal device may also be called user equipment (UE), subscriber unit (subscriber unit), terminal (terminal) or mobile station (MS) or mobile terminal (MT), etc.

[0174] For example, Figure 4The terminal device in the invention can be a mobile phone, a tablet computer or a computer with wireless transceiver function. The terminal device can also be a user station, a mobile station, a remote station, a remote terminal device, a mobile terminal device, a user terminal device, a wireless communication device, a user agent, a user device, a cellular phone, a cordless phone, a session initiation protocol (SIP) phone, a wireless local loop (WLL) station, a personal digital assistant (PDA), a handheld device with wireless communication function, a computing device, a processing device connected to a wireless modem, a vehicle-mounted device, a wearable device, a terminal device in the Internet of Things, a household appliance, a virtual reality (VR) terminal, an augmented reality (AR) terminal, a wireless terminal in industrial control, a wireless terminal in unmanned driving, a wireless terminal in telemedicine, a wireless terminal in a smart grid, a wireless terminal in a smart city, a wireless terminal in a smart home, a vehicle with vehicle-to-vehicle (V2V) communication capability, an intelligent networked vehicle, a UAV to UAV (UAV to Unmanned aerial vehicles (UAV, U2U) with communication capabilities, terminal devices in future networks, or terminal devices in future evolved public land mobile networks (PLMN), etc. are not restricted.

[0175] in, Figure 4 The access network device in the network can be any device deployed in the access network that can communicate wirelessly with the terminal device, or a chip or chip system that can be set in the above device, or a logical node or a logical module or a function implemented in software, which can be used to implement wireless physical control functions, resource scheduling and wireless resource management, wireless access control, mobility management, etc. Specifically, the network device can be a device that supports wired access or a device that supports wireless access.

[0176] Exemplarily, the access network device may be composed of one or more access network (AN) / radio access network (RAN) nodes. The AN / RAN node may be: a gNB, a transmission reception point (TRP), an evolved NodeB (eNB), a radio network controller (RNC), a NodeB (NB), a basestation controller (BSC), a base transceiver station (BTS), a home base station (e.g., home evolved NodeB, or home NodeB, HNB), a base band unit (BBU), or a wireless fidelity (Wi-Fi) access point (AP), etc.

[0177] In another example, the access network device may also be a device including a centralized unit (CU) node, or a distributed unit (DU) node, or a CU node and a DU node. For example, the access network device can be divided into CU and DU from the perspective of logical functions, with the functions of some protocol layers centrally controlled by the CU, and the functions of the remaining part or all of the protocol layers distributed in the DU, which is centrally controlled by the CU. Furthermore, the centralized unit CU can also be divided into a control plane (CU-CP) and a user plane (CU-UP). In different systems, CU (including CU-CP or CU-UP) or DU may also have different names. For example, in an open radio access network (O-RAN) system, CU may also be referred to as O-CU (open CU), DU may also be referred to as O-DU, CU-CP may also be referred to as O-CU-CP, and CU-UP may also be referred to as O-CU-UP.

[0178] in, Figure 4 The core network equipment of each network may include one or more of the following: a mobility management network element, a session management network element, a user plane network element, a network topology management network element, a unified data management network element, and a security edge protection agent network element.

[0179] in, Figure 4The mobility management network element in the network is mainly responsible for the access authentication of terminal equipment, mobility management, signaling interaction between various functional network elements, and termination of non-access stratum (NAS) layer signaling security, such as: management of user registration status, reachability status, N1 / N2 interface signaling transmission, access authentication and authorization, user connection status, user registration and network entry, tracking area update, cell switching user authentication, key security, etc.

[0180] in, Figure 4 The session management network element in the network mainly provides session management for terminal device sessions (such as session establishment, modification, and release), network protocol (Internet protocol, IP) address allocation and management, and user plane network element selection and control.

[0181] in, Figure 4 The user plane network element in the network is mainly responsible for providing user plane functions such as forwarding user messages, processing connections with data networks (DN), session anchor points, and QoS policy execution.

[0182] in, Figure 4 The network topology management element in the network mainly provides the ability to register and discover network elements in the network.

[0183] in, Figure 4 The unified data management network element in the network can provide storage capabilities for contract data, policy data, and capability exposure related data.

[0184] in, Figure 4 The security edge protection proxy network element in the PLMN is mainly responsible for providing filtering and policies for control plane interface signaling during cross-PLMN interaction, as well as hiding the network element topology within the PLMN.

[0185] Optional, Figure 4 The core network equipment of each network may also include one or more of the following: network slice selection network element, network open network element, policy control network element, network slice access control network element, authentication service network element, application function network element, specific network slice authentication and authorization network element, etc., without restriction.

[0186] by Figure 4 The communication system shown is a 5G communication system as an example. Figure 5As shown, the network element or entity corresponding to the above-mentioned access network device may be a RAN in a 5G communication system, the network element or entity corresponding to the mobility management network element may be an access and mobility management function (AMF) in a 5G communication system, the network element or entity corresponding to the session management network element may be a session management function (SMF) in a 5G communication system, the network element or entity corresponding to the user plane network element may be a user plane function (UPF) in a 5G communication system, the network element or entity corresponding to the network topology management network element may be a network repository function (NRF) in a 5G communication system, the network element or entity corresponding to the security edge protection proxy network element may be a security edge protection proxy (SEPP) in a 5G communication system, the network element or entity corresponding to the network slice selection network element may be a network slice selection function (NSSF) in a 5G communication system, the network element or entity corresponding to the network exposure network element may be a network exposure function (NEF) in a 5G communication system, and the network element or entity corresponding to the policy control network element may be a policy control function (Policy Control Function) in a 5G communication system. The network element or entity corresponding to the network slice access control network element may be the network slice admission control function (NSACF) in the 5G communication system; the network element or entity corresponding to the unified data management network element may be the unified data repository (UDR) or unified data management (UDM) in the 5G communication system; the network element or entity corresponding to the authentication service network element may be the authentication server function (AUSF) in the 5G communication system; and the network element or entity corresponding to the application function network element may be the application function (APP) in the 5G communication system.AF), the network element or entity corresponding to the specific network slice authentication and authorization network element can be a specific network slice authentication and authorization function (NSSAAF) in the 5G communication system.

[0187] Among them, Figure 5 As shown, RAN communicates with AMF through the N2 interface, RAN can also communicate with UPF through the N3 interface, UPF can communicate with SMF through the N4 interface, and UPF can also communicate with the application server in the DN through the N6 interface. Core network devices can obtain each other's services by calling each other's service-oriented interfaces, such as: core network devices can call services provided by AMF through the Namf interface, core network devices can call services provided by SMF through the Nsmf interface, core network devices can call services provided by NRF through the Nnrf interface, core network devices can call services provided by NSSF through the Nnssf interface, core network devices can call services provided by NEF through the Nnef interface, core network devices can call services provided by PCF through the Npcf interface, core network devices can call services provided by NSACF through the Nnsacf interface, core network devices can call services provided by UDM through the Nudm interface, core network devices can call services provided by UDR through the Nudr interface, core network devices can call services provided by AUSF through the Nausf interface, core network devices can call services provided by AF through the Naf interface, and core network devices can call services provided by NSSAAF through the Nnssaaf interface.

[0188] It should be noted that the terminal device, access network device and core network device in the embodiments of the present application can be one or more chips, or a system on chip (SOC), etc. Figure 4 or Figure 5 The drawings are merely exemplary and the number of devices included is not limited. Figure 4 or Figure 5 The names of the devices and links in the Figure 4 or Figure 5 In addition to the names shown, each device and each link can also be named with other names without limitation.

[0189] When implementing it specifically, Figure 4 or Figure 5 As shown in the figure, each terminal device, access network device and core network device can use Figure 6 The structure shown, or including Figure 6 Parts shown. Figure 6The present invention provides a schematic diagram of the composition of a communication device 600, which can be a terminal device or a chip or system on chip in a terminal device; it can also be an access network device or a chip or system on chip in an access network device; it can also be a core network device or a chip or system on chip in a core network device. Figure 6 As shown, the communication device 600 includes a processor 601 , a transceiver 602 , and a communication line 603 .

[0190] Furthermore, the communication device 600 may also include a memory 604. The processor 601, the memory 604 and the transceiver 602 may be connected via a communication line 603.

[0191] The processor 601 is a central processing unit (CPU), a general-purpose processor, a network processor (NP), a digital signal processor (DSP), a microprocessor, a microcontroller, a programmable logic device (PLD), or any combination thereof. The processor 601 may also be other devices with processing functions, such as circuits, devices, or software modules, without limitation.

[0192] The transceiver 602 is used to communicate with other devices or other communication networks. The other communication networks may be Ethernet, radio access network (RAN), wireless local area network (WLAN), etc. The transceiver 602 may be a module, a circuit, a transceiver or any device capable of achieving communication.

[0193] The communication line 603 is used to transmit information between the components included in the communication device 600.

[0194] The memory 604 is used to store instructions, where the instructions may be computer programs.

[0195] Among them, the memory 604 can be a read-only memory (ROM) or other types of static storage devices that can store static information and / or instructions, or a random access memory (RAM) or other types of dynamic storage devices that can store information and / or instructions, or an electrically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM) or other optical disc storage, optical disc storage (including compressed optical disc, laser disc, optical disc, digital versatile disc, Blu-ray disc, etc.), magnetic disk storage medium or other magnetic storage devices, etc., without limitation.

[0196] It should be noted that the memory 604 can exist independently of the processor 601, or can be integrated with the processor 601. The memory 604 can be used to store instructions or program codes or some data, etc. The memory 604 can be located in the communication device 600, or can be located outside the communication device 600, without limitation. The processor 601 is used to execute the instructions stored in the memory 604 to implement the network switching method provided in the following embodiments of the present application.

[0197] In one example, the processor 601 may include one or more CPUs, such as Figure 6 CPU0 and CPU1 in.

[0198] As an optional implementation, the communication device 600 includes multiple processors, for example, Figure 6 In addition to the processor 601, a processor 607 may also be included.

[0199] As an optional implementation, the communication device 600 further includes an output device 605 and an input device 606. Exemplarily, the input device 606 is a device such as a keyboard, a mouse, a microphone or a joystick, and the output device 605 is a device such as a display screen and a speaker.

[0200] It should be noted that the communication device 600 can be a desktop computer, a portable computer, a network server, a mobile phone, a tablet computer, a wireless terminal, an embedded device, a chip system or a Figure 6 In addition, Figure 4 The structure shown in the figure does not constitute a limitation on the communication device, except Figure 6 In addition to the components shown, the communication device may include more or fewer components than shown, or combine certain components, or arrange the components differently.

[0201] In the embodiment of the present application, the chip system may be composed of a chip, or may include a chip and other discrete devices.

[0202] In addition, the actions, terms, etc. involved in the various embodiments of the present application can refer to each other without limitation. The message name or parameter name in the message exchanged between the various devices in the embodiments of the present application is only an example, and other names can also be used in the specific implementation without limitation.

[0203] Combination Figure 4 or Figure 5 The communication system shown, referring to the following Figure 7 , describes the network switching method provided in the embodiment of the present application. The terminal equipment, access network equipment, core network equipment (such as mobility management network element, session management network element, user plane network element, etc.) described in the following embodiments can all have Figure 6 The processing performed by a single execution subject (terminal device or access network device or core network device) shown in the embodiments of the present application may also be divided into multiple execution subjects, which may be logically and / or physically separated without limitation.

[0204] For example, refer to the following Figure 7 , taking the case where the home network of the terminal device is the second network and the terminal device switches from the source access network device of the third network to the target access network device of the first network as an example, the network switching method provided in an embodiment of the present application is described.

[0205] The source access network device may be an access network device shared by the third network and the second network, and the terminal device may access the core network of the second network through the core network of the third network via the source access network device. The target access network device may be an access network device shared by the second network and the first network, and the terminal device may access the core network of the second network through the core network of the first network via the target access network device.

[0206] Figure 7 A flowchart of a network switching method provided in an embodiment of the present application is shown in FIG. Figure 7 As shown, the method may include:

[0207] Step 701: The terminal device sends a handover request to a third mobility management network element of a third network. Correspondingly, the third mobility management network element receives the handover request from the terminal device.

[0208] The third mobility management network element may be any one or more of one or more mobility management network elements in the third network corresponding to the session established by the third network for the terminal device. The handover request may include global identification information of the target access network device, and the handover request may be used to request handover to the target access network device.

[0209] Among them, the target access network device belongs to the first network, and the global identification information of the target access network device may include the second identification information and the identification information of the target access network device in the first network. The second identification information may be the network identification information of the first network, such as the PLMN ID of the first network, which may also be the PLMN selected when the terminal device of the first network accesses the first network, i.e., the selected PLMN, or the home PLMN of the terminal device of the first network. The second identification information may also be described as the identification information allocated by the first network to the terminal device of the first network for accessing the first network, or described as the second identification information being the PLMN of the network (i.e., the first network) to which the target access network device belongs, etc., without limitation.

[0210] Optionally, the switching request may further include first identification information.

[0211] The first identification information may be identification information allocated by the third network to the terminal device of the second network for accessing the third network.

[0212] Exemplarily, the first identification information may be a PLMN allocated by the third network to the terminal device of the second network for accessing the third network. The PLMN may also be referred to as a selected PLMN, or an alternative PLMN, etc., without limitation.

[0213] Optionally, the handover request may further include global identification information of the terminal device. The home network of the terminal device is the second network, and the global identification information of the terminal device may include fourth identification information and identification information of the terminal device in the second network, and the fourth identification information may be identification information allocated by the second network to the terminal device of the second network for accessing the second network.

[0214] Exemplarily, the fourth identification information may be the PLMN of the second network, or may be described as the PLMN of the terminal device's home network (ie, the second network), or may be described as the fourth identification information being the PLMN to which the terminal device belongs, etc., without limitation.

[0215] Exemplarily, the global identification information of the terminal device may be SUPI.

[0216] Optionally, the switching request may also include identification information of the session of the terminal device.

[0217] Optionally, the terminal device may send a switching request to the third mobility management network element when moving from the coverage area of ​​the source access network device to the coverage area of ​​the target access network device.

[0218] Step 702: The third mobility management network element obtains identification information of the second session management network element of the second network according to the handover request.

[0219] In a first possible design, the third mobility management network element may save the association relationship between the identification information of the established session and the identification information of the second session management network element when the third network establishes a session for the terminal device. When the third mobility management network element receives a handover request from the terminal device, the third mobility management network element may determine the identification information of the second session management network element corresponding to the identification information of the session of the terminal device from the pre-saved association relationship based on the identification information of the session of the terminal device in the handover request.

[0220] Among them, the second session management network element determined by this possible design can be any one or more of the one or more session management network elements in the second network corresponding to the session established by the second network for the terminal device.

[0221] In a second possible design, the third session management network element of the third network can save the association relationship between the identification information of the established session and the identification information of the second session management network element when the third network establishes a session for the terminal device. When the third mobility management network element receives a switching request from the terminal device, the third mobility management network element can determine the identification information of the session of the terminal device according to the switching request, and then send the identification information of the session to the third session management network element. The third session management network element determines the identification information of the second session management network element corresponding to the identification information of the session from the pre-saved association relationship based on the identification information of the session, and sends the identification information of the second session management network element to the third mobility management network element.

[0222] The third session management network element may be any one or more of the one or more session management network elements in the third network corresponding to the session established by the third network for the terminal device (or may be described as the third session management network element being the network element in the third network that establishes a session for the terminal device). The second session management network element determined by this possible design may be any one or more of the one or more session management network elements in the second network corresponding to the session established by the second network for the terminal device.

[0223] In a third possible design, when the third mobility management network element receives a handover request from a terminal device, the third mobility management network element may determine the identification information of the session of the terminal device according to the handover request, and send the identification information of the session to the unified data management network element. The unified data management network element determines the identification information of the second session management network element corresponding to the identification information of the session from a pre-saved association relationship according to the identification information of the session, and sends the identification information of the second session management network element to the third mobility management network element.

[0224] The unified data management network element may be a unified data management network element of a third network (or referred to as a third unified data management network element), or may be a unified data management network element of a second network (or referred to as a second unified data management network element). The second session management network element determined by this possible design may be any one or more of one or more session management network elements in the second network corresponding to a session established by the second network for the terminal device.

[0225] It should be noted that, when the third mobility management network element receives the handover request sent by the terminal device, it can execute the above step 702, obtain the identification information of the second session management network element, and then execute the following step 703. The third mobility management network element may also directly execute the following step 703 without executing the above step 702 when receiving the handover request sent by the terminal device.

[0226] Step 703: The third mobility management network element sends a fourth request to the second mobility management network element of the second network. Correspondingly, the second mobility management network element receives the fourth request from the third mobility management network element.

[0227] The second mobility management network element may be a mobility management network element in the second network specifically used to forward the switching request between different visited networks, or may be any one or more of one or more mobility management network elements corresponding to the session established by the second network for the terminal device. The fourth request may be used to request to switch the terminal device from the third network to the first network.

[0228] The third mobility management network element may carry the identification information of the target access network device and the global identification information of the terminal device in the switching request in the fourth request.

[0229] Optionally, the fourth request may also include the first identification information.

[0230] The first identification information may be identification information allocated by the third network to the terminal device of the second network for accessing the third network.

[0231] Exemplarily, the first identification information may be a PLMN allocated by the third network to the terminal device of the second network for accessing the third network. The PLMN may also be referred to as a selected PLMN, or an alternative PLMN, etc., without limitation.

[0232] Optionally, if the third mobility management network element performs the above step 702, the fourth request may include the identification information of the second session management network element determined according to the above step 702. If the third mobility management network element does not perform the above step 702, the fourth request does not include the identification information of the second session management network element determined according to the above step 702.

[0233] Optionally, the fourth request may further include identification information of the session established by the third network for the terminal device.

[0234] Optionally, the fourth request may also include network slice information corresponding to the terminal device.

[0235] Optionally, the fourth request may further include identification information of the third session management network element.

[0236] The third mobility management network element may determine the identification information of the third session management network element according to the identification information of the session established by the third network for the terminal device.

[0237] Optionally, the fourth request may further include context information of the terminal device stored in the third mobility management network element.

[0238] Optionally, the fourth request may be an AMF redirect message.

[0239] Step 704: The second mobility management network element obtains identification information of a second session management network element of the second network.

[0240] In a first possible design, when the fourth request includes identification information of the second session management network element, the second mobility management network element may determine the identification information of the second session management network element according to the fourth request.

[0241] Among them, the second session management network element determined by this possible design can be any one or more of the one or more session management network elements in the second network corresponding to the session established by the second network for the terminal device.

[0242] In a second possible design, the second mobility management network element may save the association relationship between the identification information of the established session and the identification information of the second session management network element when the second network establishes a session for the terminal device. When the second mobility management network element receives the fourth request from the third mobility management network element, the second mobility management network element may determine the identification information of the session established for the terminal device according to the fourth request, and then determine the identification information of the second session management network element corresponding to the identification information of the session of the terminal device from the pre-saved association relationship according to the identification information.

[0243] If the fourth request includes identification information of a session established by the third network for the terminal device, the second mobility management network element may determine the identification information of the second session management network element based on the identification information. Alternatively, the second mobility management network element may also determine the identification information of the session of the terminal device based on the global identification information of the terminal device in the fourth request, and then determine the identification information of the second session management network element.

[0244] Among them, the second session management network element determined by this possible design can be any one or more of the one or more session management network elements in the second network corresponding to the session established by the second network for the terminal device.

[0245] In a third possible design, the third session management network element may save the association relationship between the identification information of the established session and the identification information of the second session management network element when the third network establishes a session for the terminal device. When the second mobility management network element receives the fourth request from the third mobility management network element, the second mobility management network element may determine the identification information of the session established for the terminal device according to the fourth request, and then send the identification information of the session to the third session management network element. The third session management network element determines the identification information of the second session management network element corresponding to the identification information of the session from the pre-saved association relationship based on the identification information of the session, and sends the identification information of the second session management network element to the second mobility management network element.

[0246] Among them, the second session management network element determined by this possible design can be any one or more of the one or more session management network elements in the second network corresponding to the session established by the second network for the terminal device.

[0247] In a fourth possible design, the second unified data management network element may save the association relationship between the identification information of the established session and the identification information of the second session management network element when the second network establishes a session for the terminal device. When the second mobility management network element receives the fourth request from the third mobility management network element, the second mobility management network element may determine the identification information of the session established for the terminal device according to the fourth request, and then send the identification information of the session to the second unified data management network element. The second unified data management network element determines the identification information of the second session management network element corresponding to the identification information of the session from the pre-saved association relationship based on the identification information of the session, and sends the identification information of the second session management network element to the second mobility management network element.

[0248] Among them, the second session management network element determined by this possible design can be any one or more of the one or more session management network elements in the second network corresponding to the session established by the second network for the terminal device.

[0249] In a fifth possible design, the second mobility management network element may also randomly determine the identification information of the second session management network element according to a preset configuration.

[0250] Among them, the network element information of one or more session management network elements in the second network can be pre-configured on the second mobility management network element. When the second mobility management network element receives the fourth request from the third mobility management network element, the second mobility management network element can randomly select one or more session management network elements from the pre-configured network element information as the second session management network element, that is, the second session management network element determined by this possible design can be any one or more session management network elements in the second network. The second session management network element can be any one or more of the one or more session management network elements in the second network corresponding to the session established by the second network for the terminal device, or the second session management network element can also be one or more session management network elements in the second network that are not related to the session established by the second network for the terminal device, without limitation.

[0251] It should be noted that, when the second mobility management network element receives the fourth request sent by the third mobility management network element, it may execute the above step 704, obtain the identification information of the second session management network element, and then execute the following step 705. The second mobility management network element may also not execute the above step 704 when receiving the fourth request sent by the third mobility management network element, and directly execute the following step 705.

[0252] Step 705: The second mobility management network element sends a third request to the first mobility management network element of the first network. Correspondingly, the first mobility management network element receives the third request from the second mobility management network element.

[0253] The third request may be used to request switching of the terminal device from the third network to the first network.

[0254] The second mobility management network element may determine the first identification information according to the fourth request, and determine the second identification information according to the global identification information of the target access network device in the fourth request. The first identification information is the identification information assigned by the third network to the terminal device of the second network for accessing the third network (for example, a different PLMN assigned by the third network), and the second identification information is the identification information assigned by the first network to the terminal device of the first network for accessing the first network (for example, the PLMN of the first network).

[0255] According to the first identification information, the second mobility management network element can determine that the terminal device is a roaming user in a different network.

[0256] Based on the first identification information and the second identification information, the second mobility management network element can determine that the terminal device switches from the third network to the first network. If the second mobility management network element supports the terminal device switching from the third network to the first network, the second mobility management network element can send a third request to the first mobility management network element of the first network.

[0257] If the second mobility management network element supports communication with the third network and supports communication with the first network, it can be considered that the second mobility management network element supports the switching of the terminal device from the third network to the first network.

[0258] In a first possible design, the second mobility management network element may determine the first mobility management network element based on the second identification information.

[0259] Among them, network element information of mobility management network elements of different networks may be pre-configured on the second mobility management network element (such as configuring network element information of one or more mobility management network elements of the first network, network element information of one or more mobility management network elements of the third network, etc.). When the second mobility management network element determines that it is necessary to send a third request to the first mobility management network element of the first network, the second mobility management network element may determine the first network according to the second identification information, and then randomly select one or more mobility management network elements of the first network as the first mobility management network element from the pre-configured network element information.

[0260] That is, the first mobility management network element determined by the possible design may be any one or more mobility management network elements in the first network. The first mobility management network element may be a mobility management network element corresponding to the target access network device in the first network, or may be a mobility management network element in the first network that is unrelated to the target access network device, without limitation.

[0261] In a second possible design, the second mobility management network element may determine the first mobility management network element through a service discovery process.

[0262] Among them, the second mobility management network element can send a service discovery request to the topology management network element of the second network (or referred to as the second topology management network element), and the service discovery request may include the global identification information of the target access network device. The service discovery request is used to request the discovery of the mobility management network element associated with the target access network device. The second topology management network element can send the service discovery request to the topology management network element of the first network (or referred to as the first topology management network element), and the first topology management network element determines the mobility management network element corresponding to the target access network device (i.e., the first mobility management network element) according to the service discovery request, and carries the identification information of the first mobility management network element in the service discovery response and sends it to the second mobility management network element through the second topology management network element.

[0263] That is, the first mobility management network element determined by this possible design may be a mobility management network element in the first network corresponding to the target access network device.

[0264] Based on the above description, when the second mobility management network element sends the third request to the first mobility management network element, the information in the fourth request may be carried in the third request.

[0265] The third request may include the global identification information of the target access network device and the global identification information of the terminal device.

[0266] Optionally, if the second mobility management network element performs the above step 704, the third request may include the identification information of the second session management network element determined according to the above step 704. If the second mobility management network element does not perform the above step 704, the third request does not include the identification information of the second session management network element determined according to the above step 704.

[0267] Optionally, the third request may further include identification information of a session established by the third network for the terminal device.

[0268] Optionally, the third request may also include network slice information corresponding to the terminal device.

[0269] Optionally, the third request may further include identification information of a third session management network element.

[0270] Optionally, the third request may also include context information of the terminal device stored in the third mobility management network element.

[0271] Optionally, the third request may further include third identification information, where the third identification information is identification information allocated by the first network to the terminal device of the second network for accessing the first network.

[0272] Exemplarily, the third identification information may be a PLMN allocated by the first network to the terminal device of the second network for accessing the first network. The PLMN may also be referred to as a selected PLMN, or an alternative PLMN, etc., without limitation.

[0273] Specifically, when determining to send the third request to the first mobility management network element, the second mobility management network element may determine the third identification information, and send the third request to the first mobility management network element through the third identification information.

[0274] Step 706: The first mobility management network element obtains identification information of the second session management network element of the second network.

[0275] In a first possible design, when the third request includes identification information of the second session management network element, the first mobility management network element may determine the identification information of the second session management network element based on the third request.

[0276] Among them, the second session management network element determined by this possible design can be any one or more of the one or more session management network elements in the second network corresponding to the session established by the second network for the terminal device, or it can also be one or more session management network elements in the second network that are unrelated to the session established by the second network for the terminal device, without restriction.

[0277] In a second possible design, when the third request includes network slice information corresponding to the terminal device, the first mobility management network element can determine the identification information of the second session management network element based on the network slice information.

[0278] The first mobility management network element may determine the identification information of the second session management network element through a service discovery process.

[0279] Exemplarily, the first mobility management network element may send a service discovery request to the first topology management network element, and the service discovery request may include network slice information, and the service discovery request is used to request the discovery of a session management network element associated with the network slice information. The first topology management network element may send the service discovery request to the second topology management network element, and the second topology management network element determines the session management network element (i.e., the second session management network element) corresponding to the network slice information based on the service discovery request, and carries the identification information of the second session management network element in the service discovery response and sends it to the first mobility management network element through the first topology management network element.

[0280] Among them, the second session management network element determined by this possible design can be any one or more of the one or more session management network elements in the second network corresponding to the session established by the second network for the terminal device, or it can also be one or more session management network elements in the second network that are unrelated to the session established by the second network for the terminal device, without restriction.

[0281] In a third possible design, the first mobility management network element may also randomly determine the identification information of the second session management network element according to a preset configuration.

[0282] Among them, the network element information of one or more session management network elements in the second network can be pre-configured on the first mobility management network element. When the first mobility management network element receives the third request from the second mobility management network element, the first mobility management network element can randomly select one or more session management network elements from the pre-configured network element information as the second session management network element, that is, the second session management network element determined by this possible design can be any one or more session management network elements in the second network. The second session management network element can be any one or more of the one or more session management network elements in the second network corresponding to the session established by the second network for the terminal device, or the second session management network element can also be one or more session management network elements in the second network that are not related to the session established by the second network for the terminal device, without limitation.

[0283] Step 707: The first mobility management network element sends a first request to the first session management network element of the first network. Correspondingly, the first session management network element receives the first request from the first mobility management network element of the first network.

[0284] The first request may be used to request establishment of a session for the terminal device, and the first request may include identification information of the second session management network element.

[0285] In the first possible design, when the third request includes the global identification information of the target access network device, the first mobility management network element can determine the session management network element corresponding to the target access network device in the first network as the first session management network element based on the global identification information of the target access network device.

[0286] In the second possible design, when the third request includes network slice information, the first mobility management network element can determine the session management network element corresponding to the network slice information in the first network as the first session management network element based on the network slice information.

[0287] Based on the above description, when the first mobility management network element sends the first request to the first session management network element, the information in the third request may also be carried in the first request.

[0288] The first request may include the global identification information of the target access network device and the global identification information of the terminal device.

[0289] Optionally, the first request may further include identification information of a session established by the third network for the terminal device.

[0290] Optionally, the first request may further include identification information of a third session management network element.

[0291] Optionally, the first request may also include context information of the terminal device stored in the third mobility management network element.

[0292] Step 708: The first session management network element sends a second request to the second session management network element. Correspondingly, the second session management network element receives the second request from the first session management network element.

[0293] The second request may be used to request to obtain context information of the terminal device.

[0294] The first session management network element may determine the second session management network element according to the first request, and then send the second request to the second session management network element.

[0295] Optionally, when the first session management network element sends the second request to the second session management network element, the information in the first request may also be carried in the second request.

[0296] Optionally, the second request may further include identification information of a session established by the third network for the terminal device.

[0297] Optionally, the second request may further include identification information of a third session management network element.

[0298] Step 709: The second session management network element sends a fifth request to a third session management network element of the third network. Correspondingly, the third session management network element receives the fifth request from the second session management network element.

[0299] The fifth request may be used to request to obtain context information of the terminal device.

[0300] The second session management network element may determine the third session management network element according to the identification information of the session established by the third network for the terminal device included in the second request, and then send the fifth request to the third session management network element. Alternatively, the second session management network element may also determine the third session management network element according to the identification information of the third session management network element included in the second request, and then send the fifth request to the third session management network element.

[0301] Optionally, the fifth request may include identification information of the session established by the third network for the terminal device.

[0302] Step 710: The third session management network element sends a fifth response to the second session management network element. Correspondingly, the second session management network element receives the fifth response from the third session management network element.

[0303] The fifth response may include context information of the terminal device stored in the third session management network element.

[0304] The third session management network element may determine the context information of the terminal device according to the fifth request, and then carry the context information in the fifth response and send it to the second session management network element.

[0305] Step 711: The second session management network element sends a second response to the first session management network element. Correspondingly, the first session management network element receives the second response from the second session management network element.

[0306] The second response may include context information of the terminal device stored in the third session management network element.

[0307] Step 712: The first session management network element establishes a session for the terminal device according to the second response.

[0308] The first network, the second network and the third network can refer to the following Figure 8 The method shown is to establish a data forwarding tunnel corresponding to the session for the terminal device, referring to the following Fig. 9 The method shown in the figure forwards the service data of the terminal device through the established data forwarding tunnel, and refers to the following Fig.10 The method shown informs the terminal device that it is allowed to switch from the third network to the first network, so that the terminal device can switch from the source access network device to the target access network device to achieve network switching.

[0309] Based on the above Figure 7In the method shown, the home network (i.e., the second network) of the terminal device can assist the terminal device in switching between different visited networks participating in network sharing (e.g., switching from the third network to the first network). That is, when the terminal device switches between different visited networks participating in network sharing, the mobility management network element of the home network can transfer the context information of the terminal device between the mobility management network elements of different visited networks (i.e., the second mobility management network element assists the first mobility management network element in obtaining the context information of the terminal device stored in the third mobility management network element), and the session management network element of the home network can transfer the context information of the terminal device between the session management network elements of different visited networks (i.e., the second session management network element assists the first session management network element in obtaining the context information of the terminal device stored in the third session management network element), assist the session management network elements of different visited networks in establishing data forwarding tunnels, realize the switching of the terminal device between different visited networks (i.e., realize the switching of the terminal device between the third network and the first network), and at the same time ensure the service continuity of the terminal device during the switching process and improve the communication performance.

[0310] With the above Figure 3 Compared with the network switching based on roaming in different networks, the above Figure 3 The network switching of the inter-network roaming shown only supports the switching between the visited network and the home network that participate in network sharing. In the embodiment of the present application, when the terminal device switches between different visited networks that participate in network sharing, since different visited networks cannot communicate directly, such as the switching signaling between the mobility management network element of the first network and the mobility management network element of the third network cannot be directly transmitted, the session management network element of the first network cannot directly obtain the context information of the terminal device stored in the session management network element of the third network, but the mobility management network element and the session management network element of the home network perform indirect information forwarding and data acquisition and forwarding. Therefore, the mobility management network element of the third network needs to inform the mobility management network element of the first network of the identification information of the session management network element of the home network that can assist the session management network element of the first network in obtaining the context information of the terminal device during the switching. In this way, the switching of the terminal device between different visited networks is realized, and at the same time, the service continuity of the terminal device during the switching process is guaranteed, and the communication performance is improved.

[0311] Figure 8 A flowchart of a process for establishing a data forwarding tunnel provided in an embodiment of the present application is shown in FIG. Figure 8 As shown, the method may include:

[0312] Step 801: The third session management network element sends second tunnel information and third tunnel information to the second session management network element. Correspondingly, the second session management network element receives the second tunnel information and third tunnel information from the third session management network element.

[0313] Among them, the second tunnel information can be used to establish an uplink data forwarding tunnel between the source access network device of the third network and the third user plane network element of the third network, and the third tunnel information can be used to establish a downlink data forwarding tunnel between the second user plane network element and the third user plane network element of the second network.

[0314] The third user plane network element may be one or more of the one or more user plane network elements in the third network corresponding to the session established by the third network for the terminal device. The second user plane network element may be one or more of the one or more user plane network elements in the second network corresponding to the session established by the second network for the terminal device.

[0315] Optionally, the third session management network element may carry the second tunnel information and the third tunnel information in a fifth response and send the response to the second session management network element.

[0316] Optionally, the third session management network element may send a session establishment request to the third user plane network element. The third user plane network element may allocate the second tunnel information and the third tunnel information according to the session establishment request, and send them to the third session management network element. When the third session management network element receives the second tunnel information and the third tunnel information, it may carry them in a fifth response and send them to the second session management network element.

[0317] Step 802: The second session management network element sends third tunnel information to the second user plane network element. Correspondingly, the second user plane network element receives the third tunnel information from the second session management network element.

[0318] Step 803: The second session management network element sends second tunnel information to the first session management network element. Correspondingly, the first session management network element receives the second tunnel information from the second session management network element.

[0319] Optionally, the second session management network element may carry the second tunnel information in a second response and send it to the first session management network element.

[0320] Step 804: The second session management network element sends fourth tunnel information to the third session management network element. Correspondingly, the third session management network element receives the fourth tunnel information from the second session management network element.

[0321] The fourth tunnel information may be used by the second user plane network element and the third user plane network element to establish an uplink data forwarding tunnel.

[0322] Optionally, the second session management network element may send a session establishment request to the second user plane network element, and the second user plane network element may allocate the first tunnel information and the fourth tunnel information according to the session establishment request, and send them to the second session management network element. When the second session management network element receives the first tunnel information and the fourth tunnel information, it may execute step 804 to send the fourth tunnel information to the third session management network element, and may also execute the following step 806 to send the first tunnel information to the first session management network element.

[0323] The first tunnel information may be used to establish a data forwarding tunnel between a first user plane network element and a second user plane network element of the first network.

[0324] The first user plane network element may be one or more user plane network elements in the first network corresponding to the session established by the first network for the terminal device.

[0325] Step 805: The third session management network element sends fourth tunnel information to the third user plane network element. Correspondingly, the third user plane network element receives the fourth tunnel information from the third session management network element.

[0326] Step 806: The second session management network element sends the first tunnel information to the first session management network element. Correspondingly, the first session management network element receives the first tunnel information from the second session management network element.

[0327] The second session management network element may carry the first tunnel information in a second response and send it to the first session management network element.

[0328] Step 807: The first session management network element sends first tunnel information to the first user plane network element.

[0329] Step 808: The first session management network element sends the fifth tunnel information to the second session management network element. Correspondingly, the second session management network element receives the fifth tunnel information from the first session management network element.

[0330] The fifth tunnel information may be used by the first user plane network element and the second user plane network element to establish an uplink data forwarding tunnel.

[0331] Optionally, the first session management network element may send a session establishment request to the first user plane network element, and the first user plane network element may allocate fifth tunnel information according to the session establishment request and send it to the first session management network element. When the first session management network element receives the fifth tunnel information, it may send it to the second session management network element.

[0332] Step 809: The second session management network element sends the fifth tunnel information to the second user plane network element. Correspondingly, the second user plane network element receives the fifth tunnel information from the second session management network element.

[0333] Step 810: The first session management network element sends second tunnel information to the first mobility management network element. Correspondingly, the first mobility management network element receives the second tunnel information from the first session management network element.

[0334] Optionally, the first session management network element may carry the second tunnel information in the first response and send it to the first mobility management network element.

[0335] Step 811: The first mobility management network element sends second tunnel information to the second mobility management network element. Correspondingly, the second mobility management network element receives the second tunnel information from the first mobility management network element.

[0336] Optionally, the first mobility management network element may carry the second tunnel information in a third response and send the third response to the second mobility management network element.

[0337] The third response may be used to indicate that the first network allows the terminal device to switch from the third network to the first network.

[0338] Step 812: The second mobility management network element sends the second tunnel information to the third mobility management network element. Correspondingly, the third mobility management network element receives the second tunnel information from the second mobility management network element.

[0339] The second mobility management network element may carry the second tunnel information in a fourth response and send the response to the third mobility management network element.

[0340] The fourth response may be used to indicate that the first network allows the terminal device to switch from the third network to the first network.

[0341] Step 813: The third mobility management network element sends the second tunnel information to the source access network device. Correspondingly, the source access network device receives the second tunnel information from the third mobility management network element.

[0342] Based on the above Figure 8 The method shown can establish a data forwarding tunnel between the source access network device, the third user plane network element, the second user plane network element, and the first user plane network element, so as to facilitate the subsequent source access network device to send the service data of the terminal device to the first user plane network element through the third user plane network element and the second user plane network element, thereby ensuring the service continuity of the terminal device during the switching process.

[0343] Fig. 9 A schematic diagram of forwarding service data of a terminal device provided in an embodiment of the present application, such as Fig. 9 As shown, the method may include:

[0344] Step 901: The source access network device sends service data of the terminal device to the third user plane network element. Correspondingly, the third user plane network element receives the service data of the terminal device from the source access network device.

[0345] Among them, the source access network device can send the service data of the terminal device to the third user plane network element according to the second tunnel information.

[0346] Step 902: The third user plane network element sends service data of the terminal device to the second user plane network element. Correspondingly, the second user plane network element receives service data of the terminal device from the third user plane network element.

[0347] Among them, the third user plane network element can determine the second user plane network element according to the service data of the terminal device, and then send the service data of the terminal device to the second user plane network element.

[0348] Among them, the third user plane network element can send the service data of the terminal device to the second user plane network element according to the fourth tunnel information.

[0349] Step 903: The second user plane network element sends the service data of the terminal device to the first user plane network element. Correspondingly, the first user plane network element receives the service data of the terminal device from the second user plane network element.

[0350] Among them, the second user plane network element can determine the first user plane network element according to the service data of the terminal device, and then send the service data of the terminal device to the first user plane network element.

[0351] Among them, the second user plane network element can send the service data of the terminal device to the first user plane network element according to the fifth tunnel information.

[0352] Based on the above Fig. 9 The method shown in the figure, the source access network device and the user plane network elements of each network can be based on the above Figure 8 The allocated tunnel information realizes the forwarding of service data of the terminal device, ensures the service continuity of the terminal device during the switching process, and improves the communication performance.

[0353] Based on the above Figure 7 The method shown in the figure, the first network, the second network and the third network can also refer to the following Fig.10 The method shown informs the terminal device that it is allowed to switch from the third network to the first network.

[0354] Fig.10 A flowchart of a network switching method provided in an embodiment of the present application is shown in FIG. Fig.10 As shown, the method may include:

[0355] Step 713: The first session management network element sends a first response to the first mobility management network element. Correspondingly, the first mobility management network element receives the first response from the first session management network element.

[0356] The first response may be a session establishment response.

[0357] Step 714: The first mobility management network element sends a third response to the second mobility management network element. Correspondingly, the second mobility management network element receives the third response from the first mobility management network element.

[0358] The third response may be used to indicate that the first network allows the terminal device to switch from the third network to the first network.

[0359] Optionally, the third response may include identification information of the first mobility management network element.

[0360] Step 715: The second mobility management network element sends a fourth response to the third mobility management network element. Correspondingly, the third mobility management network element receives the fourth response from the second mobility management network element.

[0361] The fourth response may be used to indicate that the first network allows the terminal device to switch from the third network to the first network.

[0362] Optionally, the fourth response may include identification information of the first mobility management network element.

[0363] Step 716: The third mobility management network element notifies the terminal device to perform switching. Accordingly, the terminal device switches from the source access network device to the target access network device.

[0364] Based on the above Fig.10 According to the method shown, the terminal device can switch from the source access network device to the target access network device when the first network, the second network and the third network complete the session establishment, thereby realizing the switching of the terminal device between the third network and the first network.

[0365] Based on the above Figures 7 to 10 The method shown is as follows Fig.11 Taking the third mobility management network element as vAMF1, the third session management network element as vSMF1, the second mobility management network element as hAMF, the second session management network element as hSMF, the first mobility management network element as vAMF2, and the first session management network element as vSMF2 as examples, the network switching process of the above-mentioned terminal device switching from the source access network device to the target access network device is illustrated.

[0366] Fig.11 A flowchart of a network switching method provided in an embodiment of the present application is shown in FIG. Fig.11 As shown, the method may include:

[0367] Step 0: vAMF1 determines the identification information (hSMF ID) of hSMF.

[0368] In a first possible design, vAMF 1 may save the hSMF ID during the process of establishing a session for the terminal device in the third network.

[0369] In the second possible design, vAMF1 does not save the hSMF ID during the process of establishing a session for the terminal device in the third network. vAMF1 can send a request to vSMF1 (the request carries the session ID to be switched, that is, the identification information of the session of the terminal device), and vSMF1 obtains the corresponding hSMF ID based on the session ID and returns it to vAMF1.

[0370] In a third possible design, vAMF1 requests the hSMF ID corresponding to the session of the terminal device from vUDM (ie, the third unified data management network element) / hUDM (ie, the second unified data management network element).

[0371] Step 1: vAMF1 sends an AMF redirect message to hAMF.

[0372] Among them, the AMF redirection message may include hSMF ID, the selectedPLMN ID allocated by the first network to the terminal device, the SUPI of the terminal device, and the global identification information (target ID) of the target RAN.

[0373] Optionally, the AMF redirection message may also include UE context information (UE context information) to be switched in vAMF1.

[0374] Step 2. hAMF determines that the terminal device belongs to a roaming user in a different network based on the selected PLMN ID, SUPI, and PLMN ID information in the target ID in the AMF redirection message received from vAMF1, and that the terminal device is performing a direct handover of a shared RAN between different operators (i.e., switching from a shared RAN in a visited network to a shared RAN in another visited network). If, based on the configuration of hAMF, it is determined that the handover operation of the terminal device is supported, a session establishment request may be sent to vAMF2 to forward the information received from vAMF1 to vAMF2.

[0375] In the first possible design, hAMF is pre-configured with the interface vAMF ID corresponding to the PLMN of different operators. hAMF can determine vAMF2 by querying the configuration according to the PLMN ID in the target ID.

[0376] In the second possible design, hAMF obtains the vAMF2 ID corresponding to the target ID through the service discovery process of hNRF (ie, the second network topology management network element) and vNRF (ie, the first network topology management network element) based on the target ID.

[0377] Step 3: vAMF2 selects vSMF2 based on the message received from hAMF and sends a PDU session establishment request to vSMF2.

[0378] The session establishment request may include hSMF ID and UE context information.

[0379] Step 4: vSMF2 sends a request to the hSMF ID based on the hSMF ID obtained from the session establishment request. The request carries the session ID (such as PDU session ID) to request to obtain the SM context of the terminal device.

[0380] Step 5: hSMF requests the SM context of the terminal device from vSMF1 according to the received session ID.

[0381] Step 6: vSMF1 returns the SM context of the terminal device to hSMF.

[0382] Step 7: hSMF returns the SM context of the terminal device in vSMF1 to vSMF2.

[0383] Step 8: vSMF2 interacts with hSMF to establish a session for the terminal device.

[0384] Among them, vSMF2 can select vUPF2, send the tunnel information of vUPF2 to hSMF, and obtain the tunnel information of hUPF through hSMF.

[0385] Step 9: vSMF2 returns a session establishment response message to vAMF2.

[0386] Step 10: vAMF2 sends a session establishment response message to hAMF to notify hAMF that the session establishment on the VPLMN2 side is complete.

[0387] The session establishment response message may carry an N2 Notify URI, such as a vAMF2 ID.

[0388] Step 11: hAMF sends a session establishment response message to vAMF1.

[0389] The session establishment response message may carry an N2 Notify URI, such as a vAMF2 ID.

[0390] Step 12: vAMF1 notifies the terminal device to complete the switch.

[0391] With the above Fig.11 The difference between vAMF1 and hSMF ID is as follows: Fig.12 , hSMF ID can also be determined by hAMF, that is, Fig.11 Steps 0 to 2 in can be replaced by the following Fig.12 Follow steps 1 and 2 in .

[0392] Fig.12 A flowchart of a network switching method provided in an embodiment of the present application is shown in FIG. Fig.12 As shown, the method may include:

[0393] Step 1: vAMF sends an AMF redirect message to hAMF.

[0394] Among them, the AMF redirection message may include the selected PLMN ID allocated by the first network to the terminal device, the SUPI of the terminal device, and the target ID.

[0395] Optionally, the AMF redirection message may also include UE contextinformation to be switched in vAMF1.

[0396] Step 2. hAMF determines that the terminal device belongs to a roaming user in a different network based on the selected PLMN ID, SUPI, and PLMN ID information in the target ID in the AMF redirection message received from vAMF1, and that the terminal device is performing a direct handover of a shared RAN between different operators (i.e., switching from a shared RAN in a visited network to a shared RAN in another visited network). If, based on the configuration of hAMF, it is determined that the handover operation of the terminal device is supported, a suitable vAMF2 can be selected, and the hSMF ID currently being used by the terminal device can be determined, and an AMF redirection message is sent to vAMF2.

[0397] The AMF redirection message may include hSMF ID and N2 Notify URI (such as vAMF2 ID), and hSMFID is used to obtain the SM context of the terminal device in vSMF1.

[0398] In a first possible design, when hAMF saves the context information of the terminal device and establishes a session for the terminal device, hAMF will save the corresponding hSMF ID information.

[0399] In the second possible implementation, when hAMF does not save the context information of the terminal device, hAMF can request the hSMF ID information corresponding to the session ID (such as PDU Session ID) from vSMF1, or hAMF can request the hSMF ID information corresponding to the session ID from hUDM (i.e., the second unified data management network element).

[0400] With the above Fig.12 The hAMF determines the hSMF ID based on the session ID. Fig.13 , hSMF ID can also be determined randomly by hAMF, that is, Fig.12 Steps 1 to 7 in can be replaced by the following Fig.13 Follow steps 1 to 7 in .

[0401] Fig.13 A flowchart of a network switching method provided in an embodiment of the present application is shown in FIG. Fig.13 As shown, the method may include:

[0402] Step 1: vAMF sends an AMF redirect message to hAMF.

[0403] Among them, the AMF redirection message may include the selected PLMN ID allocated by the first network to the terminal device, the SUPI of the terminal device, the target ID, and the vSMF1 ID.

[0404] Optionally, the AMF redirection message may also include UE contextinformation to be switched in vAMF1.

[0405] Step 2. hAMF determines that the terminal device belongs to a roaming user in a different network based on the selected PLMN ID, SUPI, and PLMN ID information in the target ID in the AMF redirection message received from vAMF1, and that the terminal device is performing a direct handover of a shared RAN between different operators (i.e., switching from a shared RAN in a visited network to a shared RAN in another visited network). If, based on the configuration of hAMF, it is determined that the handover operation of the terminal device is supported, a suitable vAMF2 can be selected, and the hSMF ID can be randomly determined, and an AMF redirection message is sent to vAMF2.

[0406] The hAMF may randomly determine the hSMF ID according to the default configuration, and the hSMF ID may be an hSMF ID unrelated to the session in VPLMN1 or an hSMF ID corresponding to the session in VPLMN1, without limitation. That is, the type of the hSMF ID may be default.

[0407] Among them, the AMF redirection message may include hSMF ID, vSMF1 ID, N2 Notify URI (such as vAMF2ID), and the hSMF ID is used by vSMF2 to obtain the SM context of the terminal device in vSMF1.

[0408] Optionally, the AMF redirection message may also include UE context information.

[0409] Step 3: vAMF2 selects vSMF2 based on the message received from hAMF and sends a PDU session establishment request to vSMF2.

[0410] The session establishment request may include hSMF ID and vSMF1 ID.

[0411] Step 4: vSMF2 determines the hSMF ID and its type obtained from the session establishment request, and sends a request to the hSMF ID, which carries the vSMF1 ID, to request to obtain the SM context of the terminal device.

[0412] Step 5: hSMF requests the SM context of the terminal device from vSMF1 according to the received vSMF1 ID.

[0413] Step 6: vSMF1 returns the SM context of the terminal device to hSMF.

[0414] Step 7: hSMF returns the SM context of the terminal device in vSMF1 to vSMF2.

[0415] With the above Figures 11 to 13 The difference between the hSMF ID determined by vAMF1 or hAMF is as follows: Fig.14 , hSMF ID can also be determined by vAMF2, that is, Fig.11 Steps 0 to 7 in can be replaced by the following Fig.14 Follow steps 1 to 7 in .

[0416] Fig.14 A flowchart of a network switching method provided in an embodiment of the present application is shown in FIG. Fig.14 As shown, the method may include:

[0417] Step 1: vAMF sends an AMF redirect message to hAMF.

[0418] Among them, the AMF redirection message may include the selected PLMN ID allocated by the first network to the terminal device, the SUPI of the terminal device, the target ID, and the vSMF1 ID.

[0419] Optionally, the AMF redirection message may also include UE contextinformation to be switched in vAMF1.

[0420] Step 2. hAMF determines that the terminal device belongs to a roaming user in a different network based on the selected PLMN ID, SUPI, and PLMN ID information in the target ID in the AMF redirection message received from vAMF1, and that the terminal device is performing a direct handover of a shared RAN between different operators (i.e., switching from a shared RAN in a visited network to a shared RAN in another visited network). If, based on the configuration of hAMF, it is determined that the handover operation of the terminal device is supported, a suitable vAMF2 may be selected, and an AMF redirection message may be sent to vAMF2.

[0421] Among them, the AMF redirection message may include vSMF1 ID and N2 Notify URI (such as vAMF2 ID).

[0422] Optionally, the AMF redirection message may also include UE context information.

[0423] Step 3. vAMF2 selects hSMF ID according to the message received from hAMF and the network slice information (such as the slice information of home S-NSSAI).

[0424] Among them, vAMF2 can select the hSMF ID corresponding to the slice information of home S-NSSAI through the service discovery process of vNRF and hNRF according to the slice information of home S-NSSAI, or vAMF2 is pre-configured with the hSMF ID corresponding to the home PLMN of the terminal device, and vAMF2 can also randomly determine the hSMF ID according to the default configuration of vAMF2.

[0425] Step 4: vAMF2 selects vSMF2 based on the message received from hAMF and sends a PDU session establishment request to vSMF2.

[0426] The session establishment request may include hSMF ID and vSMF1 ID.

[0427] Step 5: vSMF2 sends a request to the hSMF ID based on the hSMF ID obtained from the session establishment request. The request carries the vSMF1 ID to request to obtain the SM context of the terminal device.

[0428] Step 6: hSMF requests the SM context of the terminal device from vSMF1 according to the received vSMF1 ID.

[0429] Step 7: vSMF1 returns the SM context of the terminal device to hSMF, and hSMF returns the SM context of the terminal device in vSMF1 to vSMF2.

[0430] It should be noted that the various embodiments of the present application can be implemented independently or in combination without limitation. If there is no special explanation or logical conflict, the terms and / or descriptions of the different embodiments provided in the present application are consistent and can be referenced to each other, and the technical features in different embodiments can be combined to form new embodiments according to their inherent logical relationships.

[0431] It is understandable that in the embodiments of the present application, the execution subject may execute some or all of the steps in the embodiments of the present application, and these steps or operations are only examples. The embodiments of the present application may also execute other operations or variations of various operations. In addition, the various steps may be executed in different orders presented in the embodiments of the present application, and it is possible that not all operations in the embodiments of the present application need to be executed.

[0432] The above mainly introduces the solution provided by the embodiment of the present application from the perspective of interaction between devices. It is understandable that, in order to realize the above functions, each device includes a hardware structure and / or software module corresponding to each function. Those skilled in the art should easily realize that, in combination with the algorithm steps of each example described in the embodiments disclosed herein, the present application can be implemented in the form of hardware or a combination of hardware and computer software. Whether a function is executed in the form of hardware or computer software driving hardware depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present application.

[0433] The embodiment of the present application can divide the functional modules of each device according to the above method example. For example, each functional module can be divided according to each function, or two or more functions can be integrated into one processing module. The above integrated module can be implemented in the form of hardware or in the form of software functional modules. It should be noted that the division of modules in the embodiment of the present application is schematic and is only a logical function division. There may be other division methods in actual implementation.

[0434] In the case of dividing each functional module into corresponding functional modules, Fig.15 A communication device 150 is shown, which can perform the above Figures 7 to 14The actions performed by the terminal device or access network device or core network device in the method shown, all relevant contents of the steps involved in the above method embodiment can be referred to the functional description of the corresponding functional module, and the technical effects that can be obtained can refer to the above method embodiment, which will not be repeated here.

[0435] Wherein, the communication device 150 may include a transceiver module 1501 and a processing module 1502. Exemplarily, the communication device 150 may be a communication device, or a chip applied to a communication device, or other combined devices, components, etc. having the functions of the above-mentioned communication device. When the communication device 150 is a communication device, the transceiver module 1501 may be a transceiver, and the transceiver may include an antenna and a radio frequency circuit, etc.; the processing module 1502 may be a processor (or a processing circuit), such as a baseband processor, and the baseband processor may include one or more CPUs. When the communication device 150 is a component having the functions of the above-mentioned communication device, the transceiver module 1501 may be a radio frequency unit; the processing module 1502 may be a processor (or a processing circuit), such as a baseband processor. When the communication device 150 is a chip system, the transceiver module 1501 may be an input and output interface of a chip (such as a baseband chip); the processing module 1502 may be a processor (or a processing circuit) of the chip system, and may include one or more central processing units. It should be understood that the transceiver module 1501 in the embodiment of the present application can be implemented by a transceiver or a transceiver-related circuit component; the processing module 1502 can be implemented by a processor or a processor-related circuit component (or, referred to as a processing circuit).

[0436] The transceiver module 1501 can be used to execute Figures 7 to 14 All transceiver operations performed by the communication device in the embodiment shown, and / or other processes used to support the technology described herein; the processing module 1502 can be used to perform Figures 7 to 14 All operations except the transceiver operations performed by the communication device in the illustrated embodiment, and / or other processes for supporting the technology described herein.

[0437] Exemplarily, when the communication device 150 is used to execute the action performed by the first session management network element, the transceiver module 1501 is used to receive a first request from the first mobility management network element of the first network, the first request is used to request to establish a session for the terminal device, and the first request includes identification information of the second session management network element of the second network, and the second network is the home network of the terminal device; the transceiver module 1501 is also used to send a second request to the second session management network element and receive a second response from the second session management network element, and the processing module 1502 is used to establish a session for the terminal device based on the second response; wherein the second request is used to request to obtain context information of the terminal device, and the second response includes the context information of the terminal device stored in the third session management network element, and the third session management network element is a network element in the third network that establishes a session for the terminal device.

[0438] In another example, when the communication device 150 is used to execute the action performed by the first mobility management network element, the transceiver module 1501 is used to receive a third request from the second mobility management network element of the second network; the third request is used to request to switch the terminal device from the third network to the first network, and the second network is the home network of the terminal device; the processing module 1502 is used to obtain the identification information of the second session management network element of the second network; the transceiver module 1501 is also used to send a first request to the first session management network element of the first network; wherein the first request is used to request to establish a session for the terminal device, and the first request includes the identification information of the second session management network element.

[0439] In another example, when the communication device 150 is used to execute the action performed by the second mobility management network element, the transceiver module 1501 is used to receive a fourth request from the third mobility management network element of the third network; wherein the fourth request is used to request to switch the terminal device from the third network to the first network, and the second network is the home network of the terminal device; the processing module 1502 is used to obtain the identification information of the second session management network element of the second network; the transceiver module 1501 is also used to send a third request to the first mobility management network element of the first network; wherein the third request is used to request to switch the terminal device from the third network to the first network, and the third request includes the identification information of the second session management network element.

[0440] In another example, when the communication device 150 is used to execute the action performed by the second session management network element, the transceiver module 1501 is used to receive a second request from the first session management network element of the first network; wherein the second request is used to request to obtain the context information of the terminal device, and the second network is the home network of the terminal device; the transceiver module 1501 is also used to send a fifth request to the third session management network element of the third network; wherein the third session management network element is a network element in the third network that establishes a session for the terminal device, and the fifth request is used to request to obtain the context information of the terminal device; the transceiver module 1501 is also used to receive a fifth response from the third session management network element; wherein the fifth response includes the context information of the terminal device stored in the third session management network element; the transceiver module 1501 is also used to send a second response to the first session management network element; wherein the second response includes the context information of the terminal device stored in the third session management network element.

[0441] In another example, when the communication device 150 is used to execute the action performed by the third mobility management network element, the transceiver module 1501 is used to receive a switching request from a terminal device; wherein the switching request includes the global identification information of the target access network device, and the switching request is used to request switching to the target access network device; the processing module 1502 is used to obtain the identification information of the second session management network element of the second network according to the switching request; wherein the second network is the home network of the terminal device; the transceiver module 1501 is also used to send a fourth request to the second mobility management network element of the second network; wherein the fourth request is used to request switching of the terminal device from the third network to the first network, and the fourth request includes the identification information of the second session management network element.

[0442] In another example, when the communication device 150 is used to execute the action performed by the second user plane network element, the transceiver module 1501 is used to receive service data of the terminal device from the third user plane network element of the third network; wherein the second network is the home network of the terminal device; the transceiver module 1501 is also used to send the service data of the terminal device to the first user plane network element of the first network.

[0443] As another possible way to achieve this, Fig.15 The transceiver module 1501 in the embodiment can be replaced by a transceiver, and the transceiver can integrate the functions of the transceiver module 1501; the processing module 1502 can be replaced by a processor, and the processor can integrate the functions of the processing module 1502. Further, Fig.15 The illustrated communication device 150 may also include a memory.

[0444] Alternatively, when the processing module 1502 is replaced by a processor and the transceiver module 1501 is replaced by a transceiver, the communication device 150 involved in the embodiment of the present application can also be Fig.16The communication device 160 shown, wherein the processor may be a logic circuit 1601, and the transceiver may be an interface circuit 1602. Further, Fig.16 The illustrated communication device 160 may also include a memory 1603 .

[0445] The embodiments of the present application also provide a computer program product, which can implement the functions of any of the above method embodiments when executed by a computer.

[0446] The embodiments of the present application also provide a computer program, which can implement the functions of any of the above method embodiments when executed by a computer.

[0447] The embodiment of the present application also provides a computer-readable storage medium. All or part of the processes in the above method embodiments can be completed by a computer program to instruct the relevant hardware, and the program can be stored in the above computer-readable storage medium. When the program is executed, it may include the processes of the above method embodiments. The computer-readable storage medium can be an internal storage unit of a terminal (including a data sending end and / or a data receiving end) in any of the above embodiments, such as a hard disk or memory of the terminal. The above computer-readable storage medium can also be an external storage device of the above terminal, such as a plug-in hard disk equipped on the above terminal, a smart memory card (smart media card, SMC), a secure digital (secure digital, SD) card, a flash card (flash card), etc. Further, the above computer-readable storage medium can also include both an internal storage unit of the above terminal and an external storage device. The above computer-readable storage medium is used to store the above computer program and other programs and data required by the above terminal. The above computer-readable storage medium can also be used to temporarily store data that has been output or is to be output.

[0448] It should be noted that the terms "first" and "second" in the specification, claims and drawings of this application are used to distinguish different objects rather than to describe a specific order. "First" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of this embodiment, unless otherwise specified, "multiple" means two or more.

[0449] In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device comprising a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products or devices.

[0450] It should be understood that in the present application, "at least one (item)" refers to one or more. "Multiple" refers to two or more. "At least two (items)" refers to two or three and more than three. "And / or" is used to describe the association relationship of associated objects, indicating that three relationships can exist. For example, "A and / or B" can mean: only A exists, only B exists, and A and B exist at the same time, where A and B can be singular or plural. The character " / " generally indicates that the associated objects before and after are in an "or" relationship. "At least one of the following items" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, at least one of a, b or c can mean: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, c can be single or multiple. “When” and “if” both mean that corresponding measures will be taken under certain objective circumstances. It does not limit the time, nor does it require any judgment when it is implemented, nor does it mean that there are other limitations.

[0451] In the embodiments of the present application, words such as "exemplary" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a concrete way for easy understanding.

[0452] In this application, "sending information to ... (terminal device)" can be understood as the destination of the information being the terminal device. It can include sending information to the terminal device directly or indirectly. "Receiving information from ... (terminal device)" can be understood as the source of the information being the terminal device, which can include receiving information from the terminal device directly or indirectly. The information may be processed as necessary between the source and destination of the information, such as format changes, but the destination can understand the valid information from the source.

[0453] Through the description of the above implementation methods, technical personnel in the relevant field can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional modules is used as an example. In actual applications, the above-mentioned functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above.

[0454] In the several embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the modules or units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another device, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0455] The units described as separate components may or may not be physically separated, and the components shown as units may be one physical unit or multiple physical units, that is, they may be located in one place or distributed in multiple different places. Some or all of the units may be selected according to actual needs to achieve the purpose of the present embodiment.

[0456] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0457] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a readable storage medium. Based on this understanding, the technical solution of the embodiment of the present application can essentially or all or part of the technical solution can be embodied in the form of a software product, which is stored in a storage medium, including a number of instructions to enable a device (which can be a single-chip microcomputer, chip, etc.) or a processor (processor) to perform all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: various media that can store program codes, such as USB flash drives, mobile hard drives, ROM, RAM, magnetic disks or optical disks.

Claims

1. A network switching method, characterized in that: The method is applied to a first session management network element of a first network, and the method includes: Receiving a first request from a first mobility management network element of the first network; wherein the first request is used to request to establish a session for a terminal device, and the first request includes identification information of a second session management network element of a second network, and the second network is a home network of the terminal device; Sending a second request to the second session management network element; wherein the second request is used to request to obtain context information of the terminal device; receiving a second response from the second session management network element; wherein the second response includes context information of the terminal device stored in a third session management network element, and the third session management network element is a network element in a third network that establishes a session for the terminal device; A session is established for the terminal device according to the second response.

2. The method according to claim 1, characterized in that: The first request also includes one or more of the following: identification information of the session established by the third network for the terminal device, and identification information of the third session management network element.

3. The method according to claim 2, characterized in that The second request includes one or more of the following: identification information of the session established by the third network for the terminal device, and identification information of the third session management network element.

4. The method according to any one of claims 1 to 3, characterized in that: The establishing a session for the terminal device according to the second response includes: Obtaining first tunnel information and second tunnel information; wherein the second response includes the first tunnel information and the second tunnel information, and the first tunnel information is used to establish a data forwarding tunnel between a first user plane network element of the first network and a second user plane network element of the second network; Sending the first tunnel information to the first user plane network element; Send a first response to the first mobility management network element; wherein the first response includes the second tunnel information.

5. The method according to claim 4, characterized in that The second tunnel information is used for establishing an uplink data forwarding tunnel between the source access network device of the third network and the third user plane network element of the third network.

6. A network switching method, characterized in that: The method is applied to a first mobility management network element of a first network, and the method includes: Receiving a third request from a second mobility management network element of a second network; wherein the third request is used to request switching of a terminal device from a third network to a first network, and the second network is a home network of the terminal device; Acquire identification information of a second session management network element of the second network; Send a first request to a first session management network element of the first network; wherein the first request is used to request to establish a session for the terminal device, and the first request includes identification information of the second session management network element.

7. The method according to claim 6, characterized in that The acquiring identification information of the second session management network element of the second network includes: determining the identification information of the second session management network element according to the third request; wherein the third request includes the identification information of the second session management network element; or The third request includes network slice information, and the identification information of the second session management network element is determined according to the network slice information; or; According to a preset configuration, the identification information of the second session management network element is randomly determined.

8. The method according to claim 6 or 7, characterized in that: The third request includes global identification information of the target access network device, and before sending the first request to the first session management network element of the first network, the method further includes: determining the first session management network element according to the global identification information of the target access network device; or The third request includes network slice information; before sending the first request to the first session management network element of the first network, the method also includes: determining the first session management network element based on the network slice information.

9. The method according to any one of claims 6 to 8, characterized in that: The third request also includes one or more of the following: identification information of the session established by the third network for the terminal device, and identification information of a third session management network element of the third network.

10. The method according to claim 9, characterized in that The first request also includes one or more of the following: identification information of the session established by the third network for the terminal device, and identification information of a third session management network element of the third network.

11. The method according to any one of claims 6 to 10, characterized in that: The method further comprises: receiving a first response from the first session management network element; wherein the first response includes second tunnel information; Send a third response to the second mobility management network element; wherein the third response is used to indicate that the first network allows the terminal device to switch from the third network to the first network, and the third response includes identification information of the first mobility management network element and the second tunnel information.

12. The method according to claim 11, characterized in that The second tunnel information is used for establishing an uplink data forwarding tunnel between the source access network device of the third network and the third user plane network element of the third network.

13. A network switching method, characterized in that: The method is applied to a second mobility management network element of a second network, where the second network is a home network of the terminal device, and the method includes: Receiving a fourth request from a third mobility management network element of a third network; wherein the fourth request is used to request switching of a terminal device from the third network to the first network; Acquire identification information of a second session management network element of the second network; Send a third request to the first mobility management network element of the first network; wherein the third request is used to request to switch the terminal device from the third network to the first network, and the third request includes identification information of the second session management network element.

14. The method according to claim 13, characterized in that The acquiring identification information of the second session management network element of the second network includes: determining the identification information of the second session management network element according to the fourth request; wherein the fourth request includes the identification information of the second session management network element; or The fourth request includes identification information of a session established by the third network for the terminal device, and according to the identification information of the session, the identification information of the second session management network element is determined from an association relationship between the pre-stored identification information of the session and the identification information of the second session management network element; or Sending identification information of a session established by the third network for the terminal device to a third session management network element of the third network, and receiving identification information of the second session management network element corresponding to the session from the third session management network element; or Sending identification information of the session established by the third network for the terminal device to the second unified data management network element of the second network, and receiving identification information of the second session management network element corresponding to the session from the second unified data management network element; or According to a preset configuration, the identification information of the second session management network element is randomly determined.

15. The method according to claim 13 or 14, characterized in that The fourth request also includes first identification information and global identification information of the target access network device; wherein the first identification information is identification information allocated by the third network to the terminal device of the second network for accessing the third network, and the global identification information of the target access network device includes second identification information, and the second identification information is identification information allocated by the first network to the terminal device of the first network for accessing the first network.

16. The method according to claim 15, characterized in that The sending a third request to the first mobility management network element of the first network includes: When the first identification information and the second identification information indicate that the terminal device switches from the third network to the first network, the third request is sent to the first mobility management network element.

17. The method according to claim 15 or 16, characterized in that Before sending the third request to the first mobility management network element of the first network, the method further includes: determining the first mobility management network element according to the second identification information; or Send a service discovery request to the second topology management network element of the second network, receive a service discovery response from the second topology management network element, and determine the first mobility management network element based on the service discovery response; wherein the service discovery request includes the global identification information of the target access network device, the service discovery request is used to request the discovery of the mobility management network element associated with the target access network device, and the service discovery response includes the identification information of the first mobility management network element.

18. The method according to any one of claims 13 to 17, characterized in that: The third request includes third identification information, where the third identification information is identification information allocated by the first network to a terminal device of the second network for accessing the first network.

19. The method according to any one of claims 13 to 18, characterized in that: The fourth request also includes one or more of the following: network slice information, global identification information of the target access network device, and identification information of the third session management network element of the third network.

20. The method according to claim 19, characterized in that The third request also includes one or more of the following: the network slice information, the global identification information of the target access network device, and the identification information of the third session management network element of the third network.

21. The method according to any one of claims 13 to 20, characterized in that: The method further comprises: receiving a third response from the first mobility management network element; wherein the third response is used to indicate that the first network allows the terminal device to switch from the third network to the first network, and the third response includes identification information of the first mobility management network element and second tunnel information; Send a fourth response to the third mobility management network element; wherein the fourth response is used to indicate that the first network allows the terminal device to switch from the third network to the first network, and the fourth response includes identification information of the first mobility management network element and the second tunnel information.

22. The method according to claim 21, characterized in that The second tunnel information is used for establishing an uplink data forwarding tunnel between the source access network device of the third network and the third user plane network element of the third network.

23. A network switching method, characterized in that: The method is applied to a second session management network element of a second network, and the method includes: Receiving a second request from a first session management network element of a first network; wherein the second request is used to request to obtain context information of a terminal device, and the second network is a home network of the terminal device; Sending a fifth request to a third session management network element of the third network; wherein the third session management network element is a network element in the third network that establishes a session for the terminal device, and the fifth request is used to request to obtain context information of the terminal device; receiving a fifth response from the third session management network element; wherein the fifth response includes context information of the terminal device stored in the third session management network element; Sending a second response to the first session management network element; wherein the second response includes the context information of the terminal device stored in the third session management network element.

24. The method according to claim 23, characterized in that The second request includes one or more of the following: identification information of the session established by the third network for the terminal device, and identification information of the third session management network element.

25. The method according to claim 23 or 24, characterized in that The method further comprises: Acquire the second tunnel information and the third tunnel information; wherein the fifth response includes the second tunnel information and the third tunnel information; Receive first tunnel information and fourth tunnel information from a second user plane network element of the second network; wherein the first tunnel information is used for the first user plane network element of the first network to establish a data forwarding tunnel with the second user plane network element of the second network, and the third tunnel information and the fourth tunnel information are used for the second user plane network element to establish a data forwarding tunnel with the third user plane network element; Sending the first tunnel information and the second tunnel information to the first session management network element; Sending the third tunnel information to the second user plane network element; The fourth tunnel information is sent to a third session management network element of the third network.

26. The method according to claim 25, characterized in that The second tunnel information is used for establishing an uplink data forwarding tunnel between the source access network device of the third network and the third user plane network element of the third network.

27. A network switching method, characterized in that: The method is applied to a third mobility management network element of a third network, and the method includes: Receiving a handover request from a terminal device; wherein the handover request includes global identification information of a target access network device, and the handover request is used to request handover to the target access network device; According to the handover request, obtaining identification information of a second session management network element of a second network; wherein the second network is a home network of the terminal device; Send a fourth request to the second mobility management network element of the second network; wherein the fourth request is used to request to switch the terminal device from the third network to the first network, and the fourth request includes identification information of the second session management network element.

28. The method according to claim 27, characterized in that The acquiring identification information of the second session management network element of the second network includes: Determine, according to the identification information of the session established by the third network for the terminal device, the identification information of the second session management network element from an association relationship between the pre-stored identification information of the session and the identification information of the second session management network element; or Sending identification information of the session established by the third network for the terminal device to a third session management network element of the third network, and receiving identification information of the second session management network element from the third session management network element; or Send identification information of the session established by the third network for the terminal device to a unified data management network element, and receive identification information of the second session management network element from the unified data management network element; wherein the unified data management network element is the third unified data management network element of the third network, or the unified data management network element is the second unified data management network element of the second network.

29. The method according to claim 27 or 28, characterized in that The fourth request also includes first identification information and global identification information of the target access network device; wherein the first identification information is identification information allocated by the third network to the terminal device of the second network for accessing the third network, and the global identification information of the target access network device includes second identification information, and the second identification information is identification information allocated by the first network to the terminal device of the first network for accessing the first network.

30. The method according to any one of claims 27 to 29, characterized in that: The method further comprises: receiving a fourth response from the second mobility management network element; wherein the fourth response is used to indicate that the first network allows the terminal device to switch from the third network to the first network, and the fourth response includes identification information and second tunnel information of the first mobility management network element of the first network, and the second tunnel information is used for the source access network device of the third network to establish an uplink data forwarding tunnel with the third user plane network element of the third network; Send the second tunnel information to the source access network device of the terminal device.

31. A network switching method, characterized in that: The method is applied to a second user plane network element of a second network, and the method includes: Receiving service data of a terminal device from a third user plane network element of a third network; wherein the second network is a home network of the terminal device; Determine a first user plane network element of a first network according to the service data of the terminal device; Send the service data of the terminal device to the first user plane network element of the first network.

32. The method according to claim 31, characterized in that The receiving service data of a terminal device from a third user plane network element of a third network includes: Sending fourth tunnel information to the second session management network element of the second network; wherein the fourth tunnel information is used for the second user plane network element and the third user plane network element to establish an uplink data forwarding tunnel; Receive the service data of the terminal device sent by the third user plane network element according to the fourth tunnel information.

33. The method according to claim 31 or 32, characterized in that The sending the service data of the terminal device to the first user plane network element of the first network includes: receiving fifth tunnel information from a second session management network element of the second network; wherein the fifth tunnel information is used for the first user plane network element and the second user plane network element to establish an uplink data forwarding tunnel; According to the fifth tunnel information, the service data of the terminal device is sent to the first user plane network element.

34. A communication device, characterized in that: The communication device includes a processor; the processor is used to run a computer program or instructions so that the communication device executes the network switching method as described in any one of claims 1 to 5, or executes the network switching method as described in any one of claims 6 to 12, or executes the network switching method as described in any one of claims 13 to 22, or executes the network switching method as described in any one of claims 23 to 26, or executes the network switching method as described in any one of claims 27 to 30, or executes the network switching method as described in any one of claims 31 to 33.

35. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer instructions or programs, which, when executed on a computer, cause the network switching method described in any one of claims 1 to 5 to be executed, or the network switching method described in any one of claims 6 to 12 to be executed, or the network switching method described in any one of claims 13 to 22 to be executed, or the network switching method described in any one of claims 23 to 26 to be executed, or the network switching method described in any one of claims 27 to 30 to be executed, or the network switching method described in any one of claims 31 to 33 to be executed.

36. A computer program product, characterized in that The computer program product includes computer instructions; when part or all of the computer instructions are executed on a computer, the network switching method described in any one of claims 1 to 5 is executed, or the network switching method described in any one of claims 6 to 12 is executed, or the network switching method described in any one of claims 13 to 22 is executed, or the network switching method described in any one of claims 23 to 26 is executed, or the network switching method described in any one of claims 27 to 30 is executed, or the network switching method described in any one of claims 31 to 33 is executed.

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