CN112533236B

CN112533236B - Communication method and device

Info

Publication number: CN112533236B
Application number: CN202010550068.2A
Authority: CN
Inventors: 陈靖; 姜传奎; 陶振宇
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2019-09-19
Filing date: 2020-06-16
Publication date: 2023-06-02
Anticipated expiration: 2040-06-16
Also published as: CN112533236A

Abstract

The application provides a communication method and a device, relates to the technical field of communication, and is used for improving the overall communication efficiency of a network. The method comprises the following steps: the first mobility management element in the first network obtains information of N intermediate session management elements capable of serving the terminal in the first network, and determines that a converged intermediate session management element (capable of providing session management in the first network and session management in the second network) of the N intermediate session management elements is the first intermediate session management element corresponding to the first session of the terminal in the first network, thereby improving overall communication efficiency of the network, for example, reducing network address resources to simplify complexity of network planning and deployment, reducing the number of nodes in the network to simplify network operation and maintenance workload, reducing signaling between network nodes to reduce network traffic load, and the like.

Description

Communication method and device

The present application claims priority from the chinese patent application filed on date 19 of 2019, 09, to the national intellectual property agency, application number 201910888796.1, application name "communication method and apparatus", which is incorporated herein by reference in its entirety.

Technical Field

The present disclosure relates to the field of communications technologies, and in particular, to a communications method and apparatus.

Background

For terminals that can access the fourth generation (the 4th generation,4G) network and the fifth generation (the 5th generation,5G) network, how to ensure that the terminal does not affect the service of the terminal when moving between the 4G network and the 5G network, so as to improve the overall communication efficiency of the network is a need to be solved.

Disclosure of Invention

The embodiment of the application provides a communication method and a communication device, which are used for improving the overall communication efficiency of a network.

In order to achieve the above purpose, the present application provides the following technical solutions:

in a first aspect, a communication method is provided, including: the first mobility management network element in the first network obtains information of N intermediate session management network elements capable of serving the terminal in the first network, if the N intermediate session management network elements comprise a converged intermediate session management network element, the first mobility management network element determines that the converged intermediate session management network element is a first intermediate session management network element corresponding to a first session of the terminal in the first network, and N is an integer greater than 0. Wherein the converged intermediate session management network element is capable of providing session management in a first network and capable of providing session management in a second network. The first network may be a 5G network, and the second network may be a 4G network. The first network may also be a 4G network, in which case the second network may be a 5G network. The method provided in the first aspect, when the first mobility management element selects the intermediate session management element, preferentially selects the converged intermediate session management element for the terminal, thereby improving overall communication efficiency of the network, for example, reducing network address resources to simplify complexity of network planning and deployment, reducing the number of nodes in the network to simplify network operation and maintenance workload, reducing signaling between network nodes to reduce network traffic load, and the like.

In one possible implementation, the first network is a 5G network and the second network is a 4G network, the method is applied in the following scenario: the first session is a first session established by the terminal on the first mobility management network element; or, the intermediate session management network element corresponding to the session already established by the terminal on the first mobility management network element is not the converged intermediate session management network element.

In one possible implementation manner, the first network is a 5G network, the second network is a 4G network, and the determining, by the first mobility management element, to fuse the intermediate session management element to be a first intermediate session management element corresponding to a first session of the terminal in the first network includes: under the condition that the intermediate session management network element corresponding to at least one session which is established on the first mobile management network element by the terminal is the converged intermediate session management network element, the first mobile management network element determines that the converged intermediate session management network element is the first intermediate session management network element corresponding to the first session. The possible implementation mode integrates the intermediate session management network element without re-establishing the session, only updating the session, and can avoid resource waste.

In one possible implementation, the first network is a 4G network and the second network is a 5G network, the method is applied in the following scenario: the first session is a first session established by the terminal on the first mobility management element.

In one possible implementation manner, the intermediate session management network element including the indication information in the information of the N intermediate session management network elements is a converged intermediate session management network element, and the method further includes: the first mobility management network element determines a converged intermediate session management network element according to the indication information.

In a possible implementation manner, the indication information is a node name when the converged intermediate session management network element is used as an intermediate session management network element in the 4G network.

In a possible implementation manner, the converged intermediate session management network element is further converged with an anchor session management network element in the 4G network, and the indication information is a node name when the converged intermediate session management network element is used as the anchor session management network element in the 4G network.

In a second aspect, a communication method is provided, including: when the terminal needs to be migrated from the source network to the target network, a second mobile management network element in the first network acquires information of N intermediate session management network elements corresponding to the session of the terminal in the source network, and determines a second intermediate session management network element corresponding to the session of the terminal in the target network according to the types of the N intermediate session management network elements. The information of the N intermediate session management network elements is used to indicate a type of each intermediate session management network element of the N intermediate session management network elements, where the type includes an independent intermediate session management network element or a converged intermediate session management network element, the converged intermediate session management network element is capable of providing session management in a first network and session management in a second network, the independent intermediate session management network element is only capable of providing session management in one of the first network and the second network, the source network is the first network, the target network is the second network, or the source network is the second network, the target network is the first network, and N is an integer greater than 0. The first network may be a 5G network, and the second network may be a 4G network. According to the method provided by the second aspect, in the case that the terminal needs to migrate from the source network to the target network, the intermediate session management network element corresponding to the session of the terminal in the target network can be determined according to whether the intermediate session management network element is the converged intermediate session management network element, if the intermediate session management network element needs to be determined for the session of the terminal in the target network, the converged intermediate session management network element can be preferentially determined for the session of the terminal in the target network, so that the session of the terminal after the network migration is anchored in the converged intermediate session management network element, thereby improving the overall communication efficiency of the network, for example, reducing the network address resource to simplify the complexity of network planning and deployment, reducing the number of nodes in the network to simplify the network operation and maintenance workload, reducing the signaling between network nodes to reduce the network traffic load and the like.

In one possible implementation manner, the source network is a first network, the first network is a 5G network, the target network is a second network, the second network is a 4G network, the second mobility management network element determines a second intermediate session management network element corresponding to a session of the terminal in the target network according to the type of the N intermediate session management network elements, and the method includes: if the N intermediate session management network elements include a converged intermediate session management network element, the second mobility management network element selects the converged intermediate session management network element of the N intermediate session management network elements as a second intermediate session management network element corresponding to the session of the terminal in the second network.

In one possible implementation, the method further includes: the second mobility management network element sends a relocation request to a third mobility management network element in the second network, wherein the relocation request comprises information of the second intermediate session management network element and indication information, and the indication information is used for indicating the second intermediate session management network element to be a converged intermediate session management network element.

In a possible implementation manner, the converged intermediate session management network element is further converged with an anchor session management network element in the 4G network, the indication information is a node name when the converged intermediate session management network element is used as the intermediate session management network element in the 4G network, and the node name when the converged intermediate session management network element is used as the intermediate session management network element in the 4G network is associated with the node name when the converged intermediate session management network element is used as the anchor session management network element in the 4G network.

The node name when the converged intermediate session management network element is used as the intermediate session management network element in the 4G network may be derived by the AMF according to the node name when the converged intermediate session management network element is used as the anchor point session management network element in the 4G network, or may be derived by the converged intermediate session management network element according to the node name when the converged intermediate session management network element is used as the anchor point session management network element in the 4G network.

In one possible implementation, the source network is a second network, the second network is a 4G network, the target network is a first network, the first network is a 5G network, n=1, and the method further includes: the second mobility management network element obtains information of M intermediate session management network elements capable of serving the terminal in the first network, wherein the information of the M intermediate session management network elements is used for indicating the type of each intermediate session management network element in the M intermediate session management network elements; the second mobility management network element determines a second intermediate session management network element corresponding to the session of the terminal in the target network according to the types of the N intermediate session management network elements, and the second mobility management network element comprises: the second mobility management network element determines a second intermediate session management network element corresponding to a second session of the terminal in the first network according to the types of the N intermediate session management network elements and the types of the M intermediate session management network elements.

In one possible implementation manner, the second mobility management element determines a second intermediate session management element corresponding to a second session of the terminal in the first network according to the type of the N intermediate session management elements and the type of the M intermediate session management elements, including: if the N intermediate session management network elements include a converged intermediate session management network element, and the converged intermediate session management network element belongs to M intermediate session management network elements, the second mobility management network element preferentially selects the converged intermediate session management network element from the M intermediate session management network elements as a second intermediate session management network element corresponding to the second session; or if the N intermediate session management network elements do not include the converged intermediate session management network element, or if the N intermediate session management network elements include the converged intermediate session management network element but the converged intermediate session management network element does not belong to the M intermediate session management network elements, the second mobility management network element preferentially selects the converged intermediate session management network element from the M intermediate session management network elements as a second intermediate session management network element corresponding to the second session. If the N intermediate session management network elements include a converged intermediate session management network element, and the converged intermediate session management network element belongs to M intermediate session management network elements, the converged intermediate session management network element selected by adopting the possible implementation manner does not need to reestablish a session, only needs to update the session, and can avoid resource waste.

In one possible implementation, the method further includes: the second mobility management network element sends a request message to the converged intermediate session management network element, wherein the request message is used for requesting the converged intermediate session management network element to update a corresponding session; the request message contains session identification which is distributed by the terminal in the second network by fusing the intermediate session management network element.

In a third aspect, a communication method is provided, including: a third mobility management network element in the second network receives a relocation request from a second mobility management network element in the first network, wherein the relocation request comprises information of a second intermediate session management network element and indication information, the second intermediate session management network element is an intermediate session management network element corresponding to a session of a terminal in the second network, which is determined by the second mobility management network element for the terminal, and the indication information is used for indicating the second intermediate session management network element to be a converged intermediate session management network element; the converged intermediate session management network element is capable of providing session management in a first network and is capable of providing session management in a second network; the third mobility management network element obtains information of M intermediate session management network elements capable of serving the terminal in the second network; and the third mobile management network element determines one converged intermediate session management network element as an intermediate session management network element corresponding to the session of the terminal in the second network according to the relocation request and the M intermediate session management network elements. The first network may be a 5G network, and the second network may be a 4G network. In the method provided in the third aspect, in the case that the terminal needs to migrate from the 5G network to the 4G network, the converged intermediate session management network element may be preferentially determined for the session of the terminal in the 4G network, so that the session of the terminal after the network migration is anchored in the converged intermediate session management network element, thereby improving the overall communication efficiency of the network, for example, reducing the network address resource to simplify the complexity of network planning and deployment, reducing the number of nodes in the network to simplify the network operation and maintenance workload, reducing the signaling between network nodes to reduce the network traffic load, and so on.

In one possible implementation, the method further includes: if the second intermediate session management network element belongs to the M intermediate session management network elements, the third mobile management network element determines that the second intermediate session management network element is an intermediate session management network element corresponding to the session of the terminal in the second network; if the second intermediate session management network element does not belong to the M intermediate session management network elements, the third mobility management network element determines that one of the M intermediate session management network elements merges the intermediate session management network element into an intermediate session management network element corresponding to the session of the terminal in the second network. If the second intermediate session management network element belongs to the M intermediate session management network elements, the converged intermediate session management network element selected by adopting the possible implementation manner does not need to reestablish the session, only needs to update the session, and can avoid resource waste.

In a fourth aspect, a communication method is provided, including: when a terminal needs to be migrated from a first network to a second network, a fourth mobility management network element in the second network acquires information of N intermediate session management network elements capable of providing services for the terminal in the second network; the fourth mobility management network element obtains information of M intermediate session management network elements serving the terminal in the first network from the user data management network element; if the newly-built session of the terminal on the fourth mobile management network element is the first session, the fourth mobile management network element determines an intermediate session management network element corresponding to the first session according to the types of the N intermediate session management network elements and the M intermediate session management network elements, wherein the types comprise an independent intermediate session management network element and a converged intermediate session management network element, the converged intermediate session management network element can provide session management in the first network and can provide session management in the second network, and the independent intermediate session management network element can only provide session management in one network of the first network and the second network. The first network may be a 5G network, and the second network may be a 4G network. The first network may also be a 4G network, in which case the second network may be a 5G network. In the method provided in the fourth aspect, in the case that the terminal needs to migrate from the first network to the second network, the converged intermediate session management network element may be preferentially determined for the session of the terminal in the second network, so that the session of the terminal after the network migration is anchored in the converged intermediate session management network element, thereby improving the overall communication efficiency of the network, for example, reducing the network address resource to simplify the complexity of network planning and deployment, reducing the number of nodes in the network to simplify the network operation and maintenance workload, reducing the signaling between network nodes to reduce the network traffic load, and so on.

In one possible implementation manner, the determining, by the fourth mobility management element, the intermediate session management element corresponding to the first session according to the N intermediate session management elements and the types of the M intermediate session management elements includes: if the converged intermediate session management network element belongs to M intermediate session management network elements and also belongs to N intermediate session management network elements, the fourth mobile management network element selects the converged intermediate session management network element which belongs to the M intermediate session management network elements and also belongs to the N intermediate session management network elements as the intermediate session management network element corresponding to the first session; if the M intermediate session management network elements do not include the converged intermediate session management network element, or if the M intermediate session management network elements include the converged intermediate session management network element but the converged intermediate session management network element of the M intermediate session management network elements does not belong to the N intermediate session management network elements, the fourth mobility management network element preferentially selects the converged intermediate session management network element of the N intermediate session management network elements as the intermediate session management network element corresponding to the first session. If the converged intermediate session management network element belongs to M intermediate session management network elements and N intermediate session management network elements, the converged intermediate session management network element selected by adopting the possible implementation mode does not need to reestablish the session, only needs to update the session, and can avoid resource waste.

In one possible implementation, the first network is a 4G network and the second network is a 5G network, where the method further includes: if the newly-built session of the terminal on the fourth mobile management network element is not the first session, the fourth mobile management network element preferentially selects a converged intermediate session management network element in the intermediate session management network elements corresponding to the established session on the fourth mobile management network element as an intermediate session management network element corresponding to the newly-built session.

In a fifth aspect, a communication method is provided, including: a network discovery network element in a first network receives a registration request from an intermediate session management network element in the first network, wherein the registration request comprises information of the intermediate session management network element, the information of the intermediate session management network element comprises indication information, and the indication information is used for indicating the intermediate session management network element to be a converged intermediate session management network element, and the converged intermediate session management network element can provide session management in the first network and can provide session management in a second network; the network discovery network element sends a registration response to the intermediate session management network element. The first network may be a 5G network, and the second network may be a 4G network. The method provided in the fifth aspect, the converged intermediate session management network element may be registered in the network discovery network element, and by carrying the indication information, the network discovery network element may determine which intermediate session management network elements are converged intermediate session management network elements, and which intermediate session management network elements are independent intermediate session management network elements, so as to support the subsequent intermediate session management network element selection and other processes.

In a sixth aspect, a communication method is provided, including: an intermediate session management network element in a first network sends a registration request to a network discovery network element in the first network, wherein the registration request comprises information of the intermediate session management network element, the information of the intermediate session management network element comprises indication information, the indication information is used for indicating the intermediate session management network element to be a converged intermediate session management network element, and the converged intermediate session management network element can provide session management in the first network and can provide session management in a second network; the intermediate session management network element receives a registration response from the network discovery network element. The first network may be a 5G network, and the second network may be a 4G network. The method provided in the sixth aspect, the converged intermediate session management network element may be registered in the network discovery network element, and by carrying the indication information, the network discovery network element may determine which intermediate session management network elements are converged intermediate session management network elements, and which intermediate session management network elements are independent intermediate session management network elements, so as to support the subsequent intermediate session management network element selection and other processes.

In a seventh aspect, a communication method is provided, including: the user data management network element receives a registration request from a converged intermediate session management network element, wherein the registration request comprises an identifier of the converged intermediate session management network element in a second network corresponding to a session managed by the converged intermediate session management network element in a first network, and the converged intermediate session management network element can provide session management in the first network and can provide session management in the second network; and the user data management network element sends a registration response to the converged intermediate session management network element. In the method provided in the seventh aspect, in the case that an N26 interface does not exist between the AMF and the MME, the user data management network element may acquire an identifier of an intermediate session management network element in the second network corresponding to the session managed by the converged intermediate session management network element in the first network, so that when the mobility management network element in the second network needs, the identifier of the intermediate session management network element in the second network corresponding to the session is sent to the mobility management network element in the second network.

In one possible implementation manner, the identifier of the converged intermediate session management network element in the second network corresponding to the session managed in the first network is obtained by deducing the node name when the converged intermediate session management network element is anchored in the second network corresponding to the session managed in the first network.

In an eighth aspect, there is provided a communication method comprising: the method comprises the steps that a converged intermediate session management network element sends a registration request to a user data management network element, wherein the registration request comprises an identifier of the converged intermediate session management network element in a second network corresponding to a session managed by the converged intermediate session management network element in a first network, and the converged intermediate session management network element can provide session management in the first network and can provide session management in the second network; the converged intermediate session management network element receives a registration response from the user data management network element. In the method provided in the eighth aspect, in the case that an N26 interface does not exist between the AMF and the MME, the user data management network element may acquire an identifier of an intermediate session management network element in the second network corresponding to the session managed by the converged intermediate session management network element in the first network, so that when the mobility management network element in the second network needs, the identifier of the intermediate session management network element in the second network corresponding to the session is sent to the mobility management network element in the second network.

In a ninth aspect, there is provided a communication apparatus, located in a first network, comprising: an obtaining unit, configured to obtain information of N intermediate session management network elements capable of serving a terminal in a first network, where the N intermediate session management network elements include a converged intermediate session management network element, where the converged intermediate session management network element is capable of providing session management in the first network and capable of providing session management in a second network, and N is an integer greater than 0; and the determining unit is used for determining the converged intermediate session management network element as a first intermediate session management network element corresponding to the first session of the terminal in the first network.

In one possible implementation, the first network is a 5G network, the second network is a 4G network, and the first session is a first session established by the terminal on the device; or, the intermediate session management network element corresponding to the session already established by the terminal on the device is not the converged intermediate session management network element.

In one possible implementation, the first network is a 5G network and the second network is a 4G network; the determining unit is specifically configured to determine, when an intermediate session management network element corresponding to at least one session that has been established by the terminal on the device is a converged intermediate session management network element, that the converged intermediate session management network element is a first intermediate session management network element corresponding to a first session.

In one possible implementation, the first network is a 4G network, the second network is a 5G network, and the first session is the first session established by the terminal on the device.

In one possible implementation manner, the intermediate session management network element including the indication information in the information of the N intermediate session management network elements is a converged intermediate session management network element; and the determining unit is also used for determining the converged intermediate session management network element according to the indication information.

In a tenth aspect, there is provided a communication apparatus, located in a first network, comprising: the terminal comprises an acquisition unit, a source network and a target network, wherein the acquisition unit is used for acquiring information of N intermediate session management network elements corresponding to a session of the terminal in the source network when the terminal needs to be migrated from the source network to the target network, the information of the N intermediate session management network elements is used for indicating the type of each intermediate session management network element in the N intermediate session management network elements, the type comprises an independent intermediate session management network element or a converged intermediate session management network element, the converged intermediate session management network element can provide session management in a first network and can provide session management in a second network, the independent intermediate session management network element can only provide session management in one network of the first network and the second network, the source network is the first network, the target network is the second network, or the source network is the second network, the target network is the first network, and N is an integer greater than 0; and the determining unit is used for determining a second intermediate session management network element corresponding to the session of the terminal in the target network according to the types of the N intermediate session management network elements.

In one possible implementation manner, the source network is a first network, the first network is a 5G network, the target network is a second network, and the second network is a 4G network, and the determining unit is specifically configured to select, when the converged intermediate session management network element is included in the N intermediate session management network elements, the converged intermediate session management network element of the N intermediate session management network elements as a second intermediate session management network element corresponding to a session of the terminal in the second network.

In one possible implementation, the apparatus further includes: a sending unit, configured to send a relocation request to a third mobility management element in the second network, where the relocation request includes information of the second intermediate session management element and indication information, where the indication information is used to indicate the second intermediate session management element as a converged intermediate session management element.

In one possible implementation, the source network is a second network, the second network is a 4G network, the target network is a first network, the first network is a 5G network, n=1; the terminal comprises an acquisition unit, a first network and a second network, wherein the acquisition unit is also used for acquiring information of M intermediate session management network elements capable of serving the terminal in the first network, and the information of the M intermediate session management network elements is used for indicating the type of each intermediate session management network element in the M intermediate session management network elements; the determining unit is specifically configured to determine a second intermediate session management network element corresponding to a second session of the terminal in the first network according to the type of the N intermediate session management network elements and the type of the M intermediate session management network elements.

In a possible implementation manner, the determining unit is specifically configured to, when the N intermediate session management network elements include a converged intermediate session management network element, and the converged intermediate session management network element belongs to M intermediate session management network elements, preferentially select, from the M intermediate session management network elements, the converged intermediate session management network element as a second intermediate session management network element corresponding to the second session; or, the determining unit is specifically configured to, when the N intermediate session management network elements do not include the converged intermediate session management network element, or when the N intermediate session management network elements include the converged intermediate session management network element but the converged intermediate session management network element does not belong to the M intermediate session management network elements, preferentially select the converged intermediate session management network element from the M intermediate session management network elements as a second intermediate session management network element corresponding to the second session.

In a possible implementation manner, the sending unit is further configured to send a request message to the converged intermediate session management network element, where the request message is used to request the converged intermediate session management network element to update the second session; the request message contains session identification which is distributed by the terminal in the second network by fusing the intermediate session management network element.

In an eleventh aspect, there is provided a communication apparatus located in a second network, comprising: a communication unit, configured to receive a relocation request from a second mobility management element in the first network, where the relocation request includes information of a second intermediate session management element and indication information, where the second intermediate session management element is an intermediate session management element corresponding to a session of the terminal in the second network determined by the second mobility management element for the terminal, and the indication information is used to indicate that the second intermediate session management element is a converged intermediate session management element; the converged intermediate session management network element is capable of providing session management in a first network and is capable of providing session management in a second network; a processing unit, configured to obtain information of M intermediate session management network elements capable of serving a terminal in a second network; and the processing unit is also used for determining one converged intermediate session management network element as the intermediate session management network element corresponding to the session of the terminal in the second network according to the relocation request and the M intermediate session management network elements.

In one possible implementation manner, if the second intermediate session management network element belongs to M intermediate session management network elements, the processing unit is specifically configured to determine that the second intermediate session management network element is an intermediate session management network element corresponding to a session of the terminal in the second network; if the second intermediate session management network element does not belong to the M intermediate session management network elements, the processing unit is specifically configured to determine that one of the M intermediate session management network elements merges the intermediate session management network element into an intermediate session management network element corresponding to a session of the terminal in the second network.

In a twelfth aspect, there is provided a communication apparatus located in a second network, comprising: an acquiring unit, configured to acquire information of N intermediate session management network elements capable of providing services for a terminal in a second network when the terminal needs to migrate from the first network to the second network; the acquisition unit is further used for acquiring information of M intermediate session management network elements for providing services for the terminal in the first network from the user data management network element; and the determining unit is used for determining an intermediate session management network element corresponding to the first session according to the types of the N intermediate session management network elements and the M intermediate session management network elements under the condition that the newly-built session of the terminal on the device is the first session, wherein the types comprise an independent intermediate session management network element and a converged intermediate session management network element, the converged intermediate session management network element can provide session management in the first network and can provide session management in the second network, and the independent intermediate session management network element can only provide session management in one network of the first network and the second network.

In a possible implementation manner, the determining unit is specifically configured to select, when there are converged intermediate session management network elements belonging to both M intermediate session management network elements and N intermediate session management network elements, an intermediate session management network element corresponding to the first session, which is a converged intermediate session management network element of the M intermediate session management network elements and the N intermediate session management network elements; the determining unit is specifically configured to, when the M intermediate session management network elements do not include the converged intermediate session management network element, or when the M intermediate session management network elements include the converged intermediate session management network element but the converged intermediate session management network element of the M intermediate session management network elements does not belong to the N intermediate session management network elements, preferentially select the converged intermediate session management network element of the N intermediate session management network elements as the intermediate session management network element corresponding to the first session.

In a possible implementation manner, the first network is a 4G network, and the second network is a 5G network, and the determining unit is further configured to, when the session newly created by the terminal on the device is not the first session, preferentially select, as the intermediate session management network element corresponding to the newly created session, a converged intermediate session management network element among the intermediate session management network elements corresponding to the session already created by the terminal on the device.

In a thirteenth aspect, there is provided a communication device, located in a first network, comprising: a processing unit and a communication unit; the processing unit is configured to receive, by using the communication unit, a registration request from an intermediate session management network element in the first network, where the registration request includes information of the intermediate session management network element, and the information of the intermediate session management network element includes indication information, where the indication information is used to indicate that the intermediate session management network element is a converged intermediate session management network element, where the converged intermediate session management network element is capable of providing session management in the first network and is capable of providing session management in a second network; the processing unit is further configured to send a registration response to the intermediate session management network element through the communication unit. The first network may be a 5G network, and the second network may be a 4G network.

In a fourteenth aspect, there is provided a communication apparatus, located in a first network, comprising: a processing unit and a communication unit; the processing unit is configured to send a registration request to a network discovery network element in the first network through the communication unit, where the registration request includes information of the intermediate session management network element, and the information of the intermediate session management network element includes indication information, where the indication information is used to indicate that the intermediate session management network element is a converged intermediate session management network element, where the converged intermediate session management network element is capable of providing session management in the first network and is capable of providing session management in a second network; the processing unit is further configured to receive a registration response from the network discovery network element via the communication unit. The first network may be a 5G network, and the second network may be a 4G network.

In a fifteenth aspect, there is provided a communication apparatus comprising: a processing unit and a communication unit; the processing unit is configured to receive, by using the communication unit, a registration request from a converged intermediate session management network element, where the registration request includes an identifier of an intermediate session management network element in a second network corresponding to a session managed by the converged intermediate session management network element in a first network, where the converged intermediate session management network element is capable of providing session management in the first network and is capable of providing session management in the second network; the processing unit is further configured to send a registration response to the converged intermediate session management network element through the communication unit.

In a sixteenth aspect, there is provided a communication apparatus comprising: a processing unit and a communication unit; the processing unit is configured to send a registration request to a user data management network element through the communication unit, where the registration request includes an identifier of an intermediate session management network element in a second network corresponding to a session managed by the converged intermediate session management network element in a first network, where the converged intermediate session management network element is capable of providing session management in the first network and is capable of providing session management in the second network; the processing unit is further configured to receive a registration response from the user data management network element via the communication unit.

A seventeenth aspect provides a communication device, comprising: a processor. The processor is connected to the memory, and the memory is configured to store computer-executable instructions, and the processor executes the computer-executable instructions stored in the memory, thereby implementing any one of the methods provided in any one of the first to eighth aspects. The memory and the processor may be integrated together or may be separate devices. In the latter case, the memory may be located within the communication device or may be located external to the communication device.

In one possible implementation, the processor includes logic circuitry, and further includes at least one of an input interface and an output interface. Wherein the output interface is for performing the act of transmitting in the respective method and the input interface is for performing the act of receiving in the respective method.

In one possible implementation, the communication device further includes a communication interface and a communication bus, the processor, the memory, and the communication interface being connected by the communication bus. The communication interface is used for executing the actions of the transceiving in the corresponding method. The communication interface may also be referred to as a transceiver. Optionally, the communication interface comprises at least one of a transmitter for performing the act of transmitting in the respective method and a receiver for performing the act of receiving in the respective method.

In one possible implementation, the communication device is present in the form of a chip product.

In an eighteenth aspect, there is provided a computer readable storage medium comprising instructions which, when run on a computer, cause the computer to perform any one of the methods provided in any one of the first to eighth aspects.

In a nineteenth aspect, there is provided a computer program product comprising instructions which, when run on a computer, cause the computer to perform any one of the methods provided in any one of the first to eighth aspects.

Technical effects caused by any implementation manner of the ninth aspect to the nineteenth aspect may be referred to technical effects caused by corresponding implementation manners of the first aspect to the eighth aspect, and are not described herein.

Drawings

FIGS. 1 and 2 are schematic diagrams of a network architecture;

fig. 3 to 10 are flowcharts of a communication method according to an embodiment of the present application;

fig. 11 is a schematic diagram of network migration provided in an embodiment of the present application;

fig. 12 is a flowchart of a communication method provided in an embodiment of the present application;

fig. 13 is a schematic diagram of network migration according to an embodiment of the present application;

Fig. 14 to 17 are flowcharts of a communication method according to an embodiment of the present application;

fig. 18 is a schematic diagram of a communication device according to an embodiment of the present disclosure;

fig. 19 is a schematic diagram of a mobility management network element according to an embodiment of the present application;

fig. 20 and fig. 21 are schematic hardware structures of a communication device according to an embodiment of the present application;

fig. 22 to 24 are flowcharts of a communication method according to an embodiment of the present application.

Detailed Description

In the description of the present application, "/" means "or" unless otherwise indicated, for example, a/B may mean a or B. "and/or" herein is merely an association relationship describing an association object, and means that three relationships may exist, for example, a and/or B may mean: a exists alone, A and B exist together, and B exists alone. Furthermore, "at least one" means one or more, and "a plurality" means two or more. The terms "first," "second," and the like do not limit the number and order of execution, and the terms "first," "second," and the like do not necessarily differ.

In this application, the terms "exemplary" or "such as" are used to mean serving as an example, instance, or illustration. Any embodiment or design described herein as "exemplary" or "for example" should not be construed as preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "such as" is intended to present related concepts in a concrete fashion.

The technical scheme provided by the embodiment of the application can be applied to a Multi-radio access technology Dual-Connectivity (MR-DC) system, a plurality of communication fusion systems and a future evolution system. For convenience of description, the embodiments of the present application take a communication convergence system of a 4G network and a 5G network as an example to exemplarily describe a method provided in the present application. It is to be understood that embodiments of the present application are equally applicable to other communication fusion systems similar to the present application. Among other things, the 4G network may also be referred to as a long term evolution (long term evolution, LTE) system or an evolved packet system (evolved packet system, EPS). The 5G network may also be referred to as a New Radio (NR) system.

In the case of deploying both the 5G network and the 4G network, the network system architecture is shown in fig. 1, in which the network element on the left side is the network element in the 4G network, and the network element on the right side is the network element in the 5G network. The N26 interface is an interface between the AMF and the MME for transferring information about the terminal between the AMF and the MME when the terminal moves between the 4G network and the 5G network. The N26 interface is an optional interface, and the N26 interface may not be deployed in the network. Wherein the function of each network element can be seen in table 1.

TABLE 1

Wherein, the Chinese definition of each network element in Table 1 is as follows: HSS: a user home server (home subscriber server); UDM: unified data management (unified data management); a-SMF: an anchor point access and mobility management function (anchor access and mobility management function); PGW-C: a packet data network gateway control plane (packet data network gateway-control plane); a-UPF: anchor user plane function (anchor-user plane function); PGW-U: a packet data network gateway user plane (packet data network gateway-user plane); I-SMF: an intermediate access and mobility management function (intermediate-access and mobility management function); SGW-C: a serving gateway control plane function (serving gateway-control plane function); I-UPF: an intermediate user plane function (intermediate-user plane function); SGW-U: a serving gateway user plane function (serving gateway-user plane function); AMF: an access and mobility management function (core access and mobility management function); MME: -a mobility management network element (mobility management entity); E-UTRAN: an evolved universal terrestrial radio access network (evolutiond-universal terrestrial radio access network); 5G-AN: a 5G access network (access network); NRF: -a network discovery function (network repository function); DNS Server: domain name service (domain name service, DNS) servers.

The terminal in the embodiment of the application can access to a 4G network and a 5G network, and is used for providing one or more of voice service and data connectivity service for a user. A terminal may also be called a User Equipment (UE), a terminal device, an access terminal, a subscriber unit, a subscriber station, a mobile station, a remote terminal, a mobile device, a user terminal, a wireless communication device, a user agent, or a user equipment. The terminal may be a Mobile Station (MS), a subscriber unit (subscriber unit), an unmanned aerial vehicle, an internet of things (internet of things, ioT) device, a Station (ST) in a wireless local area network (wireless local area networks, WLAN), a cellular phone (cellular phone), a smart phone (smart phone), a cordless phone, a wireless data card, a tablet, a session initiation protocol (session initiation protocol, SIP) phone, a wireless local loop (wireless local loop, WLL) station, a personal digital assistant (personal digital assistant, PDA) device, a laptop (machine type communication, MTC) terminal, a handheld device with wireless communication capabilities, a computing device or other processing device connected to a wireless modem, an in-vehicle device, a wearable device (also may be referred to as a wearable smart device). The terminal may also be a terminal in a next generation communication system, e.g. a terminal in a future evolved public land mobile network (public land mobile network, PLMN), etc.

Referring to fig. 1, in the case of deploying both the 5G network and the 4G network, a functional network element in the 5G network and a functional network element in the 4G network may be converged, and a converged network element defined by a third generation partnership project (3rd generation partnership project,3GPP) protocol includes: HSS+UDM, PGW-C+A-SMF, PGW-U+A-UPF. The converged network element can perform corresponding functions in either a 5G network or a 4G network. For example, hss+udm may manage both user subscription data and user dynamic data to be coordinated between multiple systems in a 5G network, and user subscription data and user dynamic data to be coordinated between multiple systems in a 4G network. The PGW-C+A-SMF can manage the anchor user plane network element in the 5G network to provide data service for the terminal to select proper anchor user plane network element, and can manage the anchor user plane network element in the 4G network to provide data service for the terminal to select proper anchor user plane network element. The PGW-u+a-UPF may provide, for the terminal, both routing and forwarding of data with the external data network in the 5G network and routing and forwarding of data with the external data network in the 4G network.

The 3GPP protocol does not define a converged intermediate session management network element and a converged intermediate user plane network element. However, in actual network deployment, referring to fig. 2, in order to improve the overall communication efficiency of the network, a converged intermediate session management network element and a converged intermediate user plane network element may be deployed.

However, AMF may not prefer to fuse intermediate session management network elements when selecting intermediate session management network elements in a 5G network. Similarly, the MME may not prefer to fuse intermediate session management network elements when selecting them in the 4G network. Therefore, the overall communication efficiency of the network cannot be improved by fusing intermediate session management network elements.

When a terminal is migrated from a 5G network to a 4G network, under the condition that an N26 interface exists, the information sent to an MME by an AMF through the N26 interface does not contain SGW-C related information, and under the condition that an N26 interface does not exist, the information acquired from an HSS by the MME does not contain SGW-C related information, so that after switching to the 4G network, a session cannot be anchored on a fused intermediate session management network element in the 5G network, and further the fused intermediate user plane network element cannot be selected through the fused intermediate session management network element. Similarly, the terminal migrates from the 4G network to the 5G network, and in the case of the N26 interface, the information sent by the MME to the AMF through the N26 interface includes SGW-C related information, but the AMF is not used when selecting the intermediate session management network element. Under the condition of no N26 interface, the information acquired by the AMF from the UDM does not contain the related information of SGW-C, so that the session is not guaranteed to be anchored on a converged intermediate session management network element in the 4G network after the switching to the 5G network, and further the converged intermediate user plane network element cannot be selected through the converged intermediate session management network element. Therefore, the overall communication efficiency of the network cannot be improved by integrating the intermediate session management network element and the intermediate user plane network element.

The application provides a communication method, in which an AMF or an MME can preferably merge intermediate session management network elements when selecting the intermediate session management network elements, and merge intermediate session management network elements in a network before switching are preferably selected when migrating from a 5G network to a 4G network or migrating from the 4G network to the 5G network, so that the overall communication efficiency of the network is improved.

To make the embodiments of the present application clearer, first, the meanings of some nouns in the embodiments of the present application are briefly described.

1. Converged intermediate session management network element and independent intermediate session management network element

The converged intermediate session management network element can perform session management (for example, manage an intermediate user plane network element, and provide data service for a terminal by selecting a suitable intermediate user plane network element) in a 5G network, or perform session management in a 4G network. For convenience of description, the converged intermediate session management network element is hereinafter denoted as I-smf+sgw-C.

The independent intermediate session management network element is an intermediate session management network element that can perform session management in only one of the 4G network and the 5G network.

Based on these two concepts, in the embodiment of the present application, the SGW-C includes two types, one is I-smf+sgw-C, and the other is an independent SGW-C, that is, an SGW-C that can perform session management only in a 4G network. I-SMF also includes two types, one is I-SMF+SGW-C, and the other is independent I-SMF, i.e. I-SMF which can only perform session management in 5G network.

2. Converged intermediate user plane network element and independent intermediate user plane network element

The converged intermediate user plane network element can perform route management in either a 5G network (e.g., providing a terminal with routing and forwarding of data between an access network element and an anchor user plane network element) or a 4G network. For convenience of description, the converged intermediate user plane network element is hereinafter denoted as I-upf+sgw-U.

The independent intermediate user plane network element is an intermediate user plane network element that can perform route management in only one of the 4G network and the 5G network.

Based on these two concepts, in the embodiment of the present application, the SGW-U includes two types, one is I-upf+sgw-U, and the other is an independent SGW-U, that is, an SGW-U that can perform route management only in a 4G network. I-UPF also includes two types, one is I-UPF+SGW-U, and the other is independent I-UPF, i.e. I-UPF that can only perform route management in 5G networks.

3. SGW Node Name (Node Name)

The SGW Node Name is used to uniquely identify an SGW-C device worldwide. Generally, in a 4G network, internet protocol (internet protocol, IP) address information of each interface of an SGW-C device corresponding to an SGW Node Name needs to be configured on a DNS Server.

In various embodiments of the present application, the SGW Node Name may be replaced by other identifiers that uniquely identify an SGW-C device worldwide.

4. SGW full tunnel endpoint identification (fully qualified tunnel endpoint identifier F-TEID)

The SGW F-TEID is an identifier allocated by the SGW-C for each served terminal, the SGW F-TEID comprises an IP address of an s11 interface of the SGW-C and a tunnel endpoint identifier (tunnel endpoint identifier, TEID), wherein the TEID uniquely identifies one terminal in the SGW-C range, namely the SGW F-TEID is used for uniquely identifying one terminal under one SGW-C.

In various embodiments of the present application, the SGW F-TEID may be replaced with other identifiers that uniquely identify a terminal under SGW-C.

5. EPS bearing identifier (beer ID)

The session identifier under each terminal in the 4G network is distributed to the terminal by the network side and is unique under the terminal.

6. Protocol data unit (protocol data unit, PDU) Session identification (Session ID)

The session identifier under each terminal in the 5G network is distributed and notified to the network side by the terminal and is unique under the terminal.

In addition, it should be noted that in the 4G network, each terminal may have multiple sessions, but each terminal may only access 1 SGW-C. In a 5G network, each terminal may have multiple sessions, and different sessions may select different I-SMFs.

The method provided in the embodiment of the present application is described in the following by way of three aspects, I-smf+sgw-C registration, selection of an intermediate session management network element during session establishment, and selection of an intermediate session management network element during network migration, and specifically by way of the following first to third portions, respectively.

A first part: registration of I-SMF+SGW-C

When SGW-C+I-SMF is used as I-SMF, registration with NRF is needed, and when SGW-C is used, configuration on DNS Server is needed.

When SGW-C+I-SMF is used as I-SMF, the application provides a communication method, as shown in FIG. 3, comprising the following steps:

301. an intermediate session management network element (i.e., I-SMF) in the first network sends a registration request to a network discovery network element (i.e., NRF) in the first network. Accordingly, the NRF receives the registration request from the I-SMF.

Wherein the first network is a 5G network. The registration request includes information of the I-SMF.

In one case, when one I-SMF is SGW-c+i-SMF, the information of the I-SMF includes indication information for indicating that the I-SMF is SGW-c+i-SMF. When one I-SMF is an independent I-SMF, the indication information is not included in the information of the I-SMF. For example, the indication information may be SGW Node Name when SGW-c+i-SMF is used as SGW-C.

In another case, when one I-SMF is SGW-C+I-SMF, the information of the I-SMF includes indication information for indicating that the I-SMF is SGW-C+I-SMF. When one I-SMF is independent I-SMF, the information of the I-SMF comprises another indication information, and the other indication information is used for indicating that the I-SMF is independent I-SMF.

In FIG. 3, the I-SMF is exemplified as SGW-C+I-SMF.

The information of the I-SMF also includes information of a location area and an interface address supported by the I-SMF, for example.

302. The NRF sends a registration response to the I-SMF. Accordingly, the I-SMF receives a registration response from the NRF.

When SGW-C+I-SMF is used as SGW-C, an operator configures tracking area identification code (tracking area identity, TAI) domain name information on a DNS Server. The TAI domain Name information includes TAI and SGW Node Name of corresponding SGW-C, service parameters (Service Parameters), IP addresses of interfaces and the like.

In one case, when one SGW-C is SGW-c+i-SMF, the Service Parameters of the SGW-C may include indication information, which may indicate that the SGW-C is SGW-c+i-SMF. When one SGW-C is an independent SGW-C, the indication information is not included in Service Parameters of the SGW-C. Illustratively, the indication information may be implemented by adding a suffix to Service Parameters. For example, the "+nc-smf" suffix is increased.

In another case, when one SGW-C is SGW-c+i-SMF, the information of the SGW-C includes indication information for indicating that the SGW-C is SGW-c+i-SMF. When one SGW-C is an independent SGW-C, the information of the SGW-C comprises another indication information, and the other indication information is used for indicating that the SGW-C is the independent SGW-C.

The method shown in the first part can register SGW-C+I-SMF into NRF, and by carrying indication information, NRF can determine which I-SMF is SGW-C+I-SMF and which I-SMF is independent I-SMF, thereby supporting the subsequent I-SMF selection and other processes. Similarly, the SGW-C+I-SMF can be configured into a DNS Server, and through configuration indication information, the DNS Server can determine which SGW-C is SGW-C+I-SMF and which SGW-C is independent SGW-C, so that subsequent SGW-C selection and other processes are supported.

The following exemplifies the registration procedure when SGW-c+i-SMF is used as I-SMF and the configuration procedure when SGW-C is used, see fig. 4, including:

401. the operator configures TAI domain name information on the DNS Server.

The TAI domain Name information includes TAI and corresponding SGW Node Name and Service Parameters of SGW-C, IP address of each interface, and the like.

Wherein, the SGW-C corresponding to TAI can be independent SGW-C or SGW-C+I-SMF.

To distinguish, service Parameters of SGW-c+i-SMF is incremented by "+nc-SMF" suffix, which may indicate that the corresponding SGW-C is SGW-c+i-SMF, compared to Service Parameters of independent SGW-C.

Illustratively, for the s8 interface, the Service Parameters format of the individual SGW-C is as follows:

"x-3gpp-SGW:x-s8-gtp", "x-3gpp-SGW:x-s8-pmip", SGW-C+I-SMF has the Service Parameters format as follows: "x-3gpp-sgw: x-s8-gtp+nc-smf", "x-3gpp-sgw: x-s8-pmip+nc-smf". For the s5 interface, the Service Parameters format of the independent SGW-C is as follows: "x-3gpp-SGW:x-s5-gtp", "x-3gpp-SGW:x-s5-pmip", SGW-C+I-SMF has the Service Parameters format as follows: "x-3gpp-sgw: x-s5-gtp+nc-smf", "x-3gpp-sgw: x-s5-pmip+nc-smf".

402. The SGW-C+I-SMF sends a registration request to the NRF as I-SMF.

The registration request includes information such as a location area and an interface address supported when the SGW-c+i-SMF is used as the I-SMF, and also includes an SGW Node Name when the SGW-c+i-SMF is used as the SGW-C, where the SGW Node Name may indicate that the corresponding SGW-C is the SGW-c+i-SMF.

Illustratively, the registration request may be: the nrf NFManagement NFRegister Request message.

403. The NRF saves the information in the registration request and returns a registration response to the SGW-c+i-SMF.

Illustratively, the registration response may be: the nrf NFManagement NFRegister Response message.

A second part: selection of intermediate session management network elements during session establishment

The second part provides a communication method, as shown in fig. 5, including:

501. the first mobility management element in the first network obtains information of N intermediate session management elements capable of serving the terminal in the first network, the N intermediate session management elements including SGW-c+i-SMF.

Wherein the SGW-c+i-SMF is capable of providing session management in a first network and session management in a second network, N being an integer greater than 0. The N intermediate session management network elements comprise one SGW-C+I-SMF, and also can comprise a plurality of SGW-C+I-SMFs.

The first network may be a 5G network, and the second network may be a 4G network. The first network may also be a 4G network, in which case the second network may be a 5G network.

502. The first mobility management element determines that the SGW-c+i-SMF is a first intermediate session management element corresponding to a first session of the terminal in the first network.

In a specific implementation, the first mobility management element may determine that one SGW-c+i-SMF of the N intermediate session management elements is the first intermediate session management element corresponding to the first session.

The first session may be any session in the terminal.

The second part provides a method, when the first mobility management network element selects the intermediate session management network element, the first mobility management network element preferentially selects the SGW-c+i-SMF for the terminal, so as to improve the overall communication efficiency of the network, for example, reduce network address resources to simplify complexity of network planning and deployment, reduce the number of nodes in the network to simplify network operation and maintenance workload, reduce signaling between network nodes to reduce network traffic load, and the like. The first mobility management element may need to select an intermediate session management element for the session due to the session establishment, the location area change of the terminal, and the like, and at this time, the first mobility management element performs step 501 and step 502.

Alternatively, in the case where the first network is a 4G network and the second network is a 5G network, the method is applied to the following scenario 1.

Scene 1, the first session, is the first session established by the terminal on the first mobility management element.

Alternatively, in the case where the first network is a 5G network and the second network is a 4G network, the method is applied to the above scenario 1 or the following scenario 2.

The intermediate session management network element corresponding to the session that the terminal has established on the first mobility management network element is not the SGW-c+i-SMF described above.

Scenario 2 may include the following two cases: 1) The intermediate session management network elements corresponding to the established session of the terminal on the first mobile management network element are all independent intermediate session management network elements; 2) The intermediate session management network elements corresponding to the established session of the terminal on the first mobility management network element comprise SGW-C+I-SMF, but the SGW-C+I-SMF does not belong to N intermediate session management network elements.

In addition, in the case where the first network is a 5G network, the second network is a 4G network, and the intermediate session management network element corresponding to at least one session that has been established by the terminal on the first mobility management network element is the SGW-c+i-SMF, step 502 may include, when implemented specifically: the first mobility management network element determines that the SGW-c+i-SMF is a first intermediate session management network element corresponding to the first session. In the possible implementation manner, the SGW-C+I-SMF does not need to reestablish the session, only needs to update the session, and can avoid resource waste.

Optionally, the intermediate session management network element including the indication information in the information of the N intermediate session management network elements is SGW-c+i-SMF, and the method further includes: the first mobility management network element determines SGW-C+I-SMF according to the indication information.

The relevant description of the indication information in the second part and other parts can be referred to the first part, and will not be repeated.

After step 502, optionally, the method further includes:

503. the SGW-c+i-SMF (i.e. the first intermediate session management network element corresponding to the first session) sends a registration request to the user data management network element (i.e. hss+udm). Accordingly, HSS+UDM receives a registration request from SGW-C+I-SMF.

The registration request includes an identifier of an intermediate session management network element in a second network corresponding to the session managed by the SGW-c+i-SMF in the first network. For example, if the second network is a 4G network, the registration request may include session level SGW Node Name information of a session managed by the SGW-c+i-SMF in the first network, where the session level SGW Node Name information is information of a SGW Node Name of an SGW-C that manages one session.

Through step 503, in the case that no N26 interface exists between the AMF and the MME, the hss+udm may obtain the identifier of the intermediate session management network element in the second network corresponding to the session managed by the SGW-c+i-SMF in the first network, so that when the mobility management network element in the second network needs, the identifier of the intermediate session management network element in the second network corresponding to the session is sent to the mobility management network element in the second network.

504. HSS+UDM sends registration response to SGW-C+I-SMF. Accordingly, the SGW-C+I-SMF receives the registration response from the HSS+UDM.

In the method provided in the second part, the process of selecting the intermediate session management network element for the terminal by the mobility management network element is related to whether an N26 interface exists between the AMF and the MME and the network where the AMF and the MME are currently located, and is described below through application scenario 1 and application scenario 2, respectively.

Application scenario 1: presence of N26 interface between AMF and MME

In the application scenario 1, information can be directly interacted between the AMF and the MME.

If the terminal accesses the 5G network, the AMF needs to select the I-SMF for the session (denoted as session 1) because of the session establishment, the location area change of the terminal, and the like. The selection procedure of I-SMF in a 5G network is exemplarily described below by means of fig. 6.

Referring to fig. 6, comprising:

601. the AMF sends a discovery request to the NRF, and performs I-SMF discovery to the NRF.

The discovery request may include information such as a location of the terminal.

Illustratively, the discovery request may be: nnrf_ NFDiscovery Request message.

602. The NRF returns a discovery response to the AMF.

The discovery response may include a candidate I-SMF list, where the list includes address information of one or more I-SMFs capable of providing related services for the terminal, and the I-SMF may be an independent I-SMF or SGW-c+i-SMF. For SGW-C+I-SMF, the discovery response also includes SGW Node Name information when SGW-C+I-SMF is used as SGW-C.

It should be noted that, the AMF may determine whether an I-SMF is SGW-c+i-SMF according to whether the I-SMF has information of a corresponding SGW Node Name. Specifically, when an I-SMF has information of a corresponding SGW Node Name, the I-SMF is SGW-C+I-SMF. Otherwise, the I-SMF is a stand alone I-SMF.

In a specific implementation, the NRF may determine, according to the location of the terminal and the location area supported by the I-SMF, an I-SMF that may serve the terminal, and send the information of the I-SMF to the AMF in a discovery response.

Illustratively, the discovery response may be: nnrf_ NFDiscovery Response message.

603. AMF selects I-SMF for session 1.

If session 1 has an I-SMF in use and the I-SMF is in the candidate I-SMF list, the AMF preferentially selects the I-SMF for session 1. In this case, the I-SMF only needs to update session 1, and does not need to reestablish session 1.

Otherwise, the AMF selects a new I-SMF (denoted as I-SMF 1) for session 1 (fig. 6 is drawn taking this case as an example, in which case I-SMF1 needs to establish session 1), specifically the following 3 cases:

case 1, session 1, is the first session established by the terminal.

In case 1, AMF preferably has I-SMF with SGW Node Name information (i.e., SGW-C+I-SMF) as the I-SMF of session 1 in the candidate I-SMF list.

Case 2, SGW-c+i-SMF where the terminal has had other session choices, is in the candidate I-SMF list.

In case 2, the AMF selects one SGW-C+I-SMF of the other session selection as the I-SMF of session 1.

Case 3, the terminal already has other sessions, but the I-SMFs corresponding to the other sessions are all independent I-SMFs or are not in the candidate I-SMF list, although being SGW-c+i-SMFs.

In case 3, the AMF preferably has the I-SMF of SGW Node Name information (i.e., SGW-c+i-SMF) as the I-SMF of session 1 in the candidate I-SMF list.

604. The AMF sends a PDU session establishment request to the I-SMF1 requesting the establishment of a PDU session.

Illustratively, the PDU session establishment request may be: nsmf_pduse_ CreateSMContext Request message.

605. After finishing the business processes such as interaction with the A-SMF according to the PDU conversation establishment request, the I-SMF1 returns a PDU conversation establishment response to the AMF, and the conversation establishment is successful.

Illustratively, the PDU session establishment response may be: nsmf_pduse_ CreateSMContext Response message.

The terminal accesses in the 4G network, and the MME needs to select SGW-C for the session (denoted as session 2) due to session establishment, location area change of the terminal, and so on. The following illustrates the SGW-C selection procedure in a 4G network by means of fig. 7.

Referring to fig. 7, comprising:

701. the MME sends a discovery request to the DNS Server, requesting SGW-C discovery.

Wherein the discovery request may include information of a location of the terminal, etc.

The discovery Request may be, for example, a DNS Request message.

702. The DNS Server returns a discovery response to the MME.

The discovery response may include a candidate SGW-C list, where the list includes SGW Node Name, service Parameters of one or more SGW-cs capable of providing relevant services for the terminal and IP address information of each interface. SGW-C is independent SGW-C or SGW-C+I-SMF. For SGW-C+I-SMF, service Parameters has a "+nc-SMF" suffix.

In a specific implementation, the DNS Server may determine SGW-cs that may serve the terminal according to the location of the terminal and the location area (e.g., TAI) supported by the SGW-cs, and send the information of these SGW-cs to the MME in a discovery response.

Illustratively, the discovery response may be: DNS Response message.

703. The MME selects SGW-C for session 2.

In a specific implementation, if the terminal has an SGW-C in use and the SGW-C is in the candidate SGW-C list, the MME preferentially selects the original SGW-C for session 2. In this case, the original SGW-C only needs to update session 2, and does not need to reestablish session 2.

Otherwise, the MME selects a new SGW-C (denoted SGW-C2) in the candidate SGW-C list (in which case SGW-C2 needs to establish session 2, as depicted by way of example in FIG. 7), and the MME prefers Service Parameters SGW-C (i.e., SGW-C+I-SMF) with a "+nc-SMF" suffix in the candidate SGW-C list as SGW-C for session 2.

704. The MME sends a session establishment request to SGW-C2 requesting that the session be established.

Illustratively, the session establishment request may be: create Session Request message.

705. After completing service processing such as interaction with PGW-C according to the session establishment request, SGW-C2 returns a session establishment response to MME, and session establishment is successful.

The session establishment response may include an SGW F-TEID allocated by the SGW-C2 to the terminal.

Illustratively, the session establishment response may be: create Session Response message.

Application scenario 2: absence of an N26 interface between AMF and MME

In the application scenario 2, information interaction between the MME and the AMF is required through hss+udm.

The terminal is accessed in the 5G network, because of the reasons of session establishment, location area change of the terminal and the like, the AMF needs to select I-SMF for the session (recorded as session 3), and report terminal level SGW Node Name information (terminal level SGW Node Name information is information of SGW Node Name of SGW-C for managing the session of one terminal) or session level SGW Node Name information to HSS+UDM. The selection procedure of I-SMF in a 5G network is exemplarily described below by means of fig. 8.

Referring to fig. 8, comprising:

801-805: similar to 601 through 605, respectively, except that the session herein is session 3, the I-SMF selected herein may be a different I-SMF than I-SMF2, herein denoted as I-SMF3.

In a first implementation, after step 805, steps 806a and 807a are performed, and in a second implementation, after step 805, steps 806b and 807b are performed.

806a, the AMF sends a first message to the HSS+UDM to report SGW Node Name information of SGW-C+I-SMF corresponding to the session of the terminal to the HSS+UDM.

In a specific implementation, in step 806a, the AMF reports to the hss+udm, which may be terminal-level SGW Node Name information or session-level SGW Node Name information. If the former is, for a terminal, only 1 SGW Node Name information is stored in HSS+UDM, and for a terminal, AMF only reports one terminal level SGW Node Name to HSS+UDM. If the terminal has multiple SGW-C+I-SMFs with SGW Node Name because of multiple sessions, one of the SGW-C+I-SMFs is selected for reporting. If the terminal-level SGW Node Name information of the terminal changes in step 802, the AMF may send the new terminal-level SGW Node Name information to hss+udm, and at this time, the first message may include the new terminal-level SGW Node Name information, so that hss+udm updates the terminal-level SGW Node Name information. If the information is the latter, for a session of a terminal, 1 SGW Node Name information is stored in hss+udm, and the SGW Node Name information is reported by AMF, and the AMF reports a session level SGW Node Name to hss+udm respectively for each session. If the session level SGW Node Name information of the terminal changes in step 802, the AMF may send the new session level SGW Node Name information to the hss+udm, and at this time, the first message may include the new session level SGW Node Name information, so that the hss+udm updates the session level SGW Node Name information.

Illustratively, if the AMF has not been registered with hss+udm for the terminal, the first message may be: the amb registers with hss+udm and sends a nudm_uecm_ Regisragtion Request message. If the AMF has been registered in hss+udm for the terminal, and after step 802, the terminal-level SGW Node Name information or session-level SGW Node Name information is changed, the first message may be: the AMF sends a Nudm_UECM_Update Request message to the HSS+UDM.

807a, hss+udm returns a first response to AMF according to the updated SGW Node Name information of the first message record.

Illustratively, the first response may be: nudm_uecm_update Response message.

806b, I-SMF3 sends a registration request as I-SMF to hss+udm.

The registration request may include a session level SGW Node Name of the session of the I-SMF 3.

Illustratively, the registration request may be: nudm_uecm_ Registration Request message.

807b, HSS+UDM records the information in the registration request, and returns a corresponding registration response to I-SMF 3.

After step 807a or 807b, steps 808a and 809a are performed if the MME is registered with hss+udm for the terminal, and steps 808b and 809b are performed if the MME is not registered with hss+udm for the terminal.

808a, hss+udm sends a second message to MME.

The second message may include a terminal-level SGW Node Name or a session-level SGW Node Name.

Illustratively, the second message may be: insert Subscriber Data Request message.

If MME only supports terminal level SGW Node Name, but HSS+UDM only stores session level SGW Node Name, HSS+UDM selects one from session level SGW Node Name as terminal level SGW Node Name.

809a, MME records terminal level SGW Node Name or session level SGW Node Name according to the second message, and returns a second response to hss+udm.

Illustratively, the second response may be: insert Subscriber Data Answer message.

808b, the MME sends a registration request to hss+udm.

Illustratively, the registration request may be: update Location Request message.

809b, hss+udm sends a registration response to MME, where the registration response includes a terminal level SGW Node Name or a session level SGW Node Name. After receiving the registration response, the MME records information in the registration response.

Illustratively, the registration response may be: update Location Answer message.

The terminal is accessed in the 4G network, because of the reasons of session establishment, position area change of the terminal and the like, the MME needs to select SGW-C for the session (recorded as session 4) and report terminal-level SGW Node Name information to HSS+UDM. The following describes an exemplary SGW-C selection procedure in a 4G network by means of fig. 9. It should be noted that, in the 4G network, there is no session level SGW Node Name, and only terminal level SGW Node Name.

Referring to fig. 9, comprising:

901-905: similar to 701-705, respectively, except that the session herein is session 4, the SGW-C selected herein may be a different SGW-C than SGW-C2, referred to herein as SGW-C4.

906. MME sends a first message to HSS+UDM to report terminal level SGW Node Name information to HSS+UDM.

If the MME has not registered on hss+udm for the terminal, the first message may be: the MME registers with hss+udm with Update Location Request message sent. If the MME has registered with hss+udm for the terminal and the terminal level SGW Node Name has changed after step 902, the first message may be: the Notify Request message sent by the MME to the hss+udm may include the changed terminal level SGW Node Name in the first message, so as to update the terminal level SGW Node Name in the hss+udm.

907. The HSS+UDM records the terminal level SGW Node Name according to the first message, and returns a first response to the MME.

After step 907, steps 908a and 909a are performed if the AMF has subscribed to the subscription data change notification on hss+udm for the terminal, and steps 908b and 909b are performed if the AMF has not subscribed to the subscription data change notification on hss+udm for the terminal.

908a, hss+udm sends a notify request message to AMF.

The notification request message includes a terminal-level SGW Node Name.

Illustratively, the notification request message may be: nudm SDM Notification Request message.

909a, AMF record the terminal level SGW Node Name in the notification request message, and return a notification response message to hss+udm.

The notification response message may be: nudm SDM Notification Response message.

908b, the AMF sends an acquisition request to hss+udm, where the acquisition request is used to request to acquire subscription data.

Illustratively, the acquisition request may be: nudm_sdm_get Request message.

909b, hss+udm sends an acquisition response to the AMF according to the acquisition request.

The acquiring response may include a terminal-level SGW Node Name. The AMF records the terminal stage SGW Node Name according to the acquisition response.

Illustratively, the fetch response may be: nudm_sdm_get Response message.

Third section: selection of intermediate session management network elements during network migration

The selection of the intermediate session management network element in the network migration process is related to whether an N26 interface exists between the AMF and the MME, and is described below through application scenario 1 and application scenario 2 respectively.

Application scenario 1: presence of N26 interface between AMF and MME

In the application scenario 1, information can be directly interacted between the AMF and the MME. The present application provides a communication method, as shown in fig. 10, including:

1001. when the terminal needs to migrate from the source network to the target network, a second mobility management network element (denoted as a second AMF) in the first network acquires information of N intermediate session management network elements corresponding to a session of the terminal in the source network, where the information of the N intermediate session management network elements is used to indicate a type of each intermediate session management network element in the N intermediate session management network elements, the type includes an independent intermediate session management network element or SGW-c+i-SMF, the source network is the first network, the target network is the second network, or the source network is the second network, the target network is the first network, and N is an integer greater than 0.

The first network may be a 5G network, and the second network may be a 4G network.

1002. And the second AMF determines a second intermediate session management network element corresponding to the session of the terminal in the target network according to the types of the N intermediate session management network elements.

In the method provided in fig. 10, in the case that the terminal needs to migrate from the source network to the target network, the intermediate session management network element corresponding to the session of the terminal in the target network may be determined according to whether the intermediate session management network element is SGW-c+i-SMF, if the intermediate session management network element needs to determine SGW-c+i-SMF for the session of the terminal in the target network, the SGW-c+i-SMF may be preferentially determined for the session of the terminal in the target network, so that the session of the terminal is anchored in the SGW-c+i-SMF after the network migration, thereby improving the overall communication efficiency of the network, for example, reducing the network address resources to simplify the complexity of network planning and deployment, reducing the number of nodes in the network to simplify the network operation and maintenance workload, reducing the signaling between network nodes to reduce the network traffic load.

The method shown in fig. 10 is described in detail below with a first scenario (the source network is a 5G network, the target network is a 4G network) and a second scenario (the source network is a 4G network, the target network is a 5G network).

First scenario: the source network is a 5G network and the target network is a 4G network.

Wherein the terminal may need to migrate from the 5G network to the 4G network due to cell handover or tracking area update, etc.

In a first scenario, in a first possible implementation manner, the N intermediate session management network elements include SGW-c+i-SMF, where step 1002 may include, in a specific implementation manner:

11 The second AMF selects SGW-c+i-SMF of the N intermediate session management network elements as a second intermediate session management network element corresponding to the session of the terminal in the 4G network.

For example, in the scenario shown in fig. 11, N intermediate session management network elements, that is, the second SGW-c+i-SMF, the second AMF may determine that the second SGW-c+i-SMF is the second intermediate session management network element corresponding to the session of the terminal in the 4G network.

After step 11), the second AMF may set the session management node identifier change location corresponding to the session of the terminal managed by the second intermediate session management network element in the 5G network to be false, and set the session management node identifier change location corresponding to other sessions of the terminal in the 5G network to be true.

The change position of the session management node identifier corresponding to one session is used for indicating that the intermediate session management network element corresponding to the session before and after the migration is unchanged, and the change position of the session management node identifier corresponding to one session is used for indicating that the intermediate session management network element corresponding to the session before and after the migration is changed. The session management node identification change bit may comprise one or more bits which, when different in value, represent different meanings. For example, if the session management node identifier change bit is 1 bit, the bit 1 may indicate that the session management node identifier change position is false, and the bit 0 may indicate that the session management node identifier change position is true, or vice versa.

Illustratively, based on the example shown in fig. 11, session 1, session 2, and session 3 are included in the 5G network prior to migration. If the second SGW-c+i-SMF is the second intermediate session management network element, after migration, the second AMF considers that the intermediate session management network elements corresponding to session 1 and session 2 are unchanged, and considers that the intermediate session management network element corresponding to session 3 is changed from an independent I-SMF to the second SGW-c+i-SMF. Therefore, the second AMF may set the session management node identifier positions corresponding to session 1 and session 2 to false and set the session management node identifier position corresponding to session 3 to true.

It should be noted that, the second AMF is configured to determine, based on the second intermediate session management network element determined by itself, whether the intermediate session management network element corresponding to the session before and after the migration changes, and whether the MME in the 4G network selects the second intermediate session management network element as the intermediate session management network element of the terminal is not known yet, so the second AMF finally needs to determine, in combination with other conditions, whether the intermediate session management network element corresponding to the actual session before and after the migration changes.

Optionally, after step 11), the method further comprises:

12 The second AMF sends a relocation request (denoted as a first relocation request) to a third mobility management network element (denoted as a third MME) in the 4G network, where the first relocation request includes information of the second intermediate session management network element and indication information, where the indication information is used to indicate that the second intermediate session management network element is SGW-c+i-SMF. Accordingly, the third MME receives the first relocation request from the second AMF.

Optionally, the first relocation request further includes a session identifier allocated by the second intermediate session management network element to the terminal in the 4G network, for example, an SGW F-TEID allocated by the second intermediate session management network element to the terminal.

13 A third MME obtains information of M intermediate session management network elements capable of serving terminals in the 4G network.

14 The third MME determines one SGW-C+I-SMF as an intermediate session management network element corresponding to the session of the terminal in the 4G network according to the first relocation request and the M intermediate session management network elements.

Optionally, step 14) includes, when embodied:

if the second intermediate session management network element belongs to M intermediate session management network elements, the third MME determines that the second intermediate session management network element is an intermediate session management network element corresponding to a session of a terminal in the 4G network, and in the scenario shown in fig. 11, the third MME may determine that the second SGW-c+i-SMF is a second intermediate session management network element corresponding to a session of a terminal in the 4G network, where the second intermediate session management network element does not need to reestablish the session, and only needs to update the session, so that resource waste may be avoided; or alternatively;

if the second intermediate session management network element does not belong to the M intermediate session management network elements, the third MME determines that one SGW-c+i-SMF of the M intermediate session management network elements is an intermediate session management network element corresponding to a session of the terminal in the 4G network.

It should be noted that, in the 4G network, all sessions of the terminal correspond to the same intermediate session management network element. Through step 14), after the terminal is migrated from the 5G network to the 4G network, the session of the terminal is anchored in the SGW-c+i-SMF, so as to improve the overall communication efficiency of the network, for example, reduce network address resources to simplify the complexity of network planning and deployment, reduce the number of nodes in the network to simplify the network operation and maintenance workload, reduce the signaling between network nodes to reduce the network traffic load, and so on.

In the first scenario, in a second possible implementation manner, the SGW-c+i-SMF is not included in the N intermediate session management network elements, where the method further includes:

21 The second AMF sends a relocation request (denoted as second relocation request) to the third MME, which may include the globally unique session identification of the terminal. Illustratively, the globally unique identification may be: identification of terminal + EPS Bearer ID.

22 The third MME receives the second relocation request and determines one SGW-C+I-SMF in M intermediate session management network elements as an intermediate session management network element corresponding to the session of the terminal in the 4G network.

Based on the first possible implementation manner and the second possible implementation manner, after step 14) or step 22), if the intermediate session management network element corresponding to the session of the terminal in the 4G network is denoted as a third intermediate session management network element, optionally, the method further includes the following steps 31) to 33):

31 The third MME sending a request message to the third intermediate session management network element, the request message being for requesting a session for locating the terminal.

32 The third intermediate session management network element receives the request message and locates the corresponding session according to the request message.

33 The third intermediate session management network element modifies the access type of the session corresponding to the third intermediate session management network element into a 4G network.

Before step 31), if the third MME receives the first relocation request and the second intermediate session management network element belongs to the M intermediate session management network elements, the third MME changes the session management node identifier of the terminal to be false. If the third MME receives the second relocation request or receives the first relocation request but the second intermediate session management network element does not belong to the M intermediate session management network elements, the third MME changes the session management node identification change position of the terminal to be true.

The session management node identification change position of the terminal is assumed to indicate that the corresponding intermediate session management network element of the terminal before and after the migration is unchanged, wherein as long as one session of the terminal before and after the migration is unchanged, the corresponding intermediate session management network element of the terminal before and after the migration is considered to be unchanged. The change position of the session management node identifier of a terminal is true to indicate that the corresponding intermediate session management network element of the session before and after the migration changes, wherein all the session of the terminal changes in the corresponding intermediate session management network element before and after the migration, and the terminal is considered to change in the corresponding intermediate session management network element before and after the migration. The description of the session management node identifier change bit can be found above, and will not be repeated.

In step 31), when the session management node identifier change position of the terminal is false and the session identifier allocated by the third intermediate session management network element in the 4G network by the terminal (for example, the SGW F-TEID allocated by the third intermediate session management network element for the terminal) is valid, the request message includes the session identifier allocated by the third intermediate session management network element in the 4G network by the terminal. Otherwise, the request message may include the globally unique session identification of the terminal.

Step 32) in a specific implementation, the third intermediate session management network element may locate the corresponding session for the session identifier allocated by the terminal in the 4G network or the global unique session identifier of the terminal according to the third intermediate session management network element in the request message. Wherein for the session in which the intermediate session management network element has not changed (for example, session 1 and session 2 in fig. 11), the third intermediate session management network element directly updates the session, and for the session in which the intermediate session management network element has changed (for example, session 3 in fig. 11), the third intermediate session management network element re-establishes the session.

Optionally, the method further comprises: if the session corresponding to the third intermediate session management network element (for example, session 1, session 2 and session 3 in fig. 11) is I-upf+sgw-U in the I-UPF used in the 5G network, and the session corresponding to the third intermediate session management network element can be continuously serviced, the third intermediate session management network element preferably selects the I-upf+sgw-U to continue servicing the terminal.

Based on the first possible implementation manner and the second possible implementation manner, after step 14) or step 22), optionally, the method further includes the following steps 41) and 42):

41 The third MME sends a relocation response to the second AMF, wherein the relocation response comprises a session management node identification change bit of the terminal.

42 The second AMF receives the relocation response from the third MME and records the session management node identification change bit of the terminal.

If the change position of the session management node identifier corresponding to one session of the terminal in the 5G network is true, or if the change position of the session management node identifier corresponding to one session of the terminal in the 5G network is false, the change position of the session management node identifier of the terminal is true, which indicates that the session has changed corresponding to the intermediate session management network element before and after the migration. At this time, the second AMF may send a release request to the I-SMF corresponding to the session, and the I-SMF releases the session according to the release request. Alternatively, the second AMF may send a release request to the I-SMFs corresponding to all sessions, where the I-SMF determines whether to release session resources, for example, if the access type of a session corresponding to an SGW-c+i-SMF is modified to a 4G network, the SGW-c+i-SMF determines not to release related resources of the session corresponding to the SGW-c+i-SMF.

For example, referring to fig. 11, in the scenario shown in fig. 11, where the session management node identifier change location of the terminal is false, the session management node identifier change locations of session 1 and session 2 in the second AMF are false, and the session management node identifier change location of session 3 is true, the second AMF may send a release request to the independent I-SMF in fig. 11, where the independent I-SMF releases session resources of session 3 according to the release request.

The flow of migration of a terminal from a 5G network to a 4G network is exemplarily described below with reference to fig. 12.

Referring to fig. 12, comprising:

1201. the AMF receives a migration request for requesting migration to the 4G network.

When the terminal migrates to the 4G network through the cell handover procedure, the migration request may be: handover Required message sent by 5G-AN.

When the terminal migrates to the 4G network through the tracking area update procedure, the migration request may be: and the MME sends a Context Request message.

1202. The AMF transmits a session context request message for requesting acquisition of information of each session of the terminal to each I-SMF.

Illustratively, the session context request message may be: nsmf_pduse_ RetrieveSMContext Request message.

1203. Each I-SMF returns a session context response message to the AMF.

In a specific implementation, step 1203 is performed, for a session under SGW-c+i-SMF, where the session context response message includes, in addition to EPS Bearer ID information allocated by the 4G network for the session, optionally, SGW Node Name when SGW-c+i-SMF is used as SGW-C and SGW F-TEID allocated by the SGW-C to the terminal when SGW-c+i-SMF is used as SGW-C. The AMF can determine whether an I-SMF is SGW-C+I-SMF according to whether the I-SMF has the corresponding SGW Node Name information.

Illustratively, the session context response message may be: nsmf_pduse_ RetrieveSMContext Response message.

1204. The AMF selects SGW-C in the 4G network for the terminal.

Specifically, if each session of the terminal uses one or more SGW-c+i-SMFs, the AMF may select one SGW-c+i-SMF (denoted as a first SGW-c+i-SMF) from one or more SGW-c+i-SMFs used by each session of the terminal as the SGW-C of the terminal in the 4G network.

Optionally, if each session of the terminal uses one or more SGW-c+i-SMFs, the AMF further sets a session level SGW Change Indication identifier of a session managed by the first SGW-c+i-SMF in the 5G network to False, and sets a session level SGW Change Indication identifier of other sessions managed in the 5G network to True. If each session of the terminal does not use SGW-c+i-SMF, the AMF does not select SGW-C for the terminal, and the AMF sets the session level SGW Change Indication identifier of all sessions of the terminal to True.

Where session level SGW Change Indication identifies the session management node identification change bit of the session in the above.

1205. The AMF sends a relocation request to the MME.

If the AMF selects the first SGW-c+i-SMF for the terminal and the AMF obtains the SGW Node Name corresponding to the first SGW-c+i-SMF through step 602 or step 1203, the relocation request includes the SGW Node Name corresponding to the first SGW-c+i-SMF, otherwise, the relocation request does not include the SGW Node Name cell. Optionally, if the first SGW-c+i-SMF is further obtained in step 1203 as the SGW-C, the SGW F-TEID allocated to the terminal is further included in the relocation request, otherwise, the SGW F-TEID cell carries an invalid value.

If AMF does not select the first SGW-C+I-SMF for the terminal, the relocation request does not contain SGW Node Name cell, and SGW F-TEID cell carries invalid value.

When the terminal migrates to the 4G network through the cell handover procedure, the relocation request may be: forward Relocation Request message.

When the terminal migrates to the 4G network through the tracking area update procedure, the relocation request may be: context Response message.

1206. The MME sends a discovery request to the DNS Server, wherein the discovery request is used for requesting the DNS Server to perform SGW-C discovery.

Wherein the discovery request includes information such as a location of the terminal.

Illustratively, the discovery request may be: DNS Request message.

1207. And the DNS Server returns a discovery response to the MME according to the discovery request.

The discovery response contains a candidate SGW-C list that contains one or more SGW Node names, service Parameters of SGW-cs capable of providing relevant services to the terminal and IP address information of each interface. Wherein SGW-C is independent SGW-C or SGW-C+I-SMF. For SGW-C+I-SMF, service Parameters has a "+nc-SMF" suffix.

Illustratively, the discovery response may be: DNS Response message.

1208. The MME selects SGW-C of the terminal and sends a relocation response to the AMF, wherein the relocation response contains the terminal grade SGW Change Indication identification of the terminal. The AMF holds the terminal level SGW Change Indication identification in the relocation response.

Wherein the terminal level SGW Change Indication identifies, i.e. the session management node identification change bit of the terminal.

In step 1208, the MME selects SGW-C for the terminal in the candidate SGW-C list. When the relocation request carries the SGW Node Name corresponding to the first SGW-c+i-SMF and the SGW Node Name is located in the SGW-C list, the SGW-C of the terminal selected by the MME is the SGW-C represented by the SGW Node Name (i.e., the first SGW-c+i-SMF), and the terminal stage SGW Change Indication identifier of the terminal is set as the spase. Otherwise, the MME selects one SGW-C of the terminal (i.e., SGW-c+i-SMF) with "+nc-SMF" suffix for Service Parameters in the candidate SGW-C list, and sets the terminal stage SGW Change Indication of the terminal to True.

For convenience of description, the SGW-C selected by the MME is hereinafter referred to as the first SGW-C.

When the terminal migrates to the 4G network through the cell handover procedure, the relocation response may be: the MME sends Forward Relocation Response message to the AMF.

When the terminal migrates to the 4G network through the tracking area update procedure, the relocation response may be: the MME sends Context Acknowledge message to the AMF.

1209. The MME sends a bearer related request to the first SGW-C.

If the terminal stage SGW Change Indication of the terminal is identified as False, and the first SGW-C is valid for the SGW F-TEID allocated to the terminal, the bearer related request may be: modify Bearer Request, which may include the SGW F-TEID allocated by the first SGW-C to the terminal.

If the terminal stage SGW Change Indication of the terminal identifies True or the SGW F-TEID allocated by the first SGW-C to the terminal is invalid, the bearer related request may be: create Session Request, the message does not have SGW F-TEID information, but contains the identity of the terminal and EPS Bearer ID information obtained in step 1203.

1210. The first SGW-C locates the corresponding session according to the bearer related request.

If the bearer related request is a Modify Bearer Request message, the first SGW-C locates the corresponding session according to the SGW F-TEID in the message.

If the Bearer related request is a Create Session Request message, the first SGW-C locates the corresponding session according to the identifier of the terminal and EPS Bearer ID information in the message.

1211. And if the first SGW-C locates the corresponding session, modifying the access type of the session to be a 4G network.

1212. For any session of the terminal in the 5G network, if the I-UPF used by the session is I-UPF+SGW-U and the I-UPF+SGW-U can continue to provide service for the session, the first SGW-C preferably selects the originally used I-UPF+SGW-U to continue to provide service for the session in the 4G network.

In this case, the first SGW-C sends a session modification request to the originally used I-UPF+SGW-U. And after the I-UPF+SGW-U completes related processing according to the session modification request, returning a session modification response to the first SGW-C.

Wherein the session modification request may be: PFCP Session Modification Request message. The session modification response may be: PFCP Session Modification Response message.

1213. And after the first SGW-C finishes service processing such as interaction with the PGW-C, returning a bearing related response to the MME.

If the bearer related request is a Modify Bearer Request message, the bearer related response may be: modify Bearer Response message.

If the bearer related request is a Create Session Request message, the bearer related response may be: create Session Response message.

1214. The AMF releases the associated resources of the session.

If, for a session, the terminal level SGW Change Indication of the terminal stored in the AMF is identified as False, and the session level SGW Change Indication of the session is identified as False, which indicates that the session is not changed by the corresponding intermediate session management network element before and after the migration, and is the first SGW-c+i-SMF, where the AMF does not send a release request to the first SGW-c+i-SMF for the session in the subsequent processing flow. Otherwise, the AMF sends a release request to the corresponding I-SMF for the session to request release of the associated resources of the session according to existing processing.

For an I-SMF, if a release request is received, but the access type of a session managed by the I-SMF in the 5G network has been modified to a 4G network, the I-SMF does not delete the session managed in the 5G network, and returns only a release response to the AMF. If a release request is received and the access type of the session managed by the I-SMF in the 5G network is not modified to the 4G network, the I-SMF deletes the session managed in the 5G network.

Illustratively, the release request may be: nsmf_pduse_ ReleaseSMContext Request message. The release response may be: nsmf_pduse_ ReleaseSMContext Response message.

The second scenario: the source network is a 4G network and the target network is a 5G network, in which case n=1.

After the terminal accesses the 4G network, the terminal may need to migrate from the 4G network to the 5G network due to cell switching or registration update.

In a second scenario, the method shown in fig. 10 further comprises: the second AMF acquires information of M intermediate session management network elements capable of serving the terminal in the 5G network, wherein the information of the M intermediate session management network elements is used for indicating the type of each intermediate session management network element in the M intermediate session management network elements. In this case, step 1002 specifically includes: 1002-A, the second AMF determines a second intermediate session management network element corresponding to a second session of the terminal in the 5G network according to the types of the N intermediate session management network elements and the types of the M intermediate session management network elements.

The second session may be any session in the terminal.

Optionally, step 1002-a may include, in particular implementations:

if the N intermediate session management network elements include SGW-c+i-SMF and the SGW-c+i-SMF belongs to M intermediate session management network elements, the second AMF preferentially selects the SGW-c+i-SMF from the M intermediate session management network elements as a second intermediate session management network element corresponding to the second session, where in this case, the SGW-c+i-SMF does not need to reestablish the session, only needs to update the session, so that resource waste can be avoided; or alternatively, the process may be performed,

If the N intermediate session management network elements do not include SGW-c+i-SMF, or if the N intermediate session management network elements include SGW-c+i-SMF but the SGW-c+i-SMF does not belong to M intermediate session management network elements, the second AMF preferentially selects one SGW-c+i-SMF from the M intermediate session management network elements as a second intermediate session management network element corresponding to the second session.

For example, referring to fig. 13, the n intermediate session management network elements are second SGW-c+i-SMFs, and for session 1 and session 2, if the second SGW-c+i-SMF belongs to M intermediate session management network elements, the second AMF may determine that the second SGW-c+i-SMF is a second intermediate session management network element corresponding to session 1 and session 2 of the terminal. For session 3, if the second SGW-c+i-SMF does not belong to M intermediate session management network elements, the second AMF may determine that one SGW-c+i-SMF of the M intermediate session management network elements is a second intermediate session management network element corresponding to session 3 of the terminal.

By the alternative method, after the terminal is migrated from the 4G network to the 5G network, the session of the terminal is anchored at the SGW-C+I-SMF, so that the overall communication efficiency of the network is improved, for example, network address resources are reduced to simplify the complexity of network planning and deployment, the number of nodes in the network is reduced to simplify the operation and maintenance workload of the network, signaling among network nodes is reduced to reduce the network traffic load and the like.

Optionally, the method further comprises:

11 A second AMF sends a request message to the SGW-c+i-SMF (i.e., a second intermediate session management network element), the request message being for requesting the SGW-c+i-SMF to update the second session; the request message includes session identifier allocated by the SGW-c+i-SMF to the terminal in the 4G network, for example, the SGW-c+i-SMF is an SGW F-TEID allocated by the terminal.

12 The SGW-C + I-SMF receives the request message and updates the second session according to the request message.

13 The SGW-C + I-SMF modifies the access type of the second session to a 5G network.

Step 12) in a specific implementation, the SGW-c+i-SMF may update the second session (for example, session 1 or session 2 in fig. 13) for the session identifier allocated by the terminal in the 4G network according to the SGW-c+i-SMF in the request message.

Optionally, the method further comprises:

if the N intermediate session management network elements include SGW-c+i-SMFs and the SGW-c+i-SMFs belong to M intermediate session management network elements, the second AMF sets a session management node change identifier position corresponding to a session (for example, session 1 and session 2 in fig. 13) managed by the SGW-c+i-SMFs in the 5G network to be false, and sets a session management node change identifier position corresponding to other sessions (for example, session 3 in fig. 13) of the terminal in the 5G network to be true; or alternatively, the process may be performed,

If the N intermediate session management network elements do not include SGW-c+i-SMF, or if the N intermediate session management network elements include SGW-c+i-SMF but the SGW-c+i-SMF does not belong to the M intermediate session management network elements, the second AMF sets the session management node change identifier corresponding to the session of the terminal in the 4G network as true.

Optionally, the method further comprises:

if the terminal has at least one session corresponding to the session management node change identification position in the 5G network is false, the second AMF judges the session management node change identification position of the terminal to be false; or alternatively, the process may be performed,

if the session management node change identification positions corresponding to all sessions of the terminal in the 5G network are false, the second AMF judges the session management node change identification positions of the terminal to be false.

Optionally, if the session management node change identifier position corresponding to at least one session in the 5G network by the terminal is true but the session management node change identifier position of the terminal is false, it indicates that there is a change in at least one intermediate session management network element corresponding to the session in the plurality of sessions in the 5G network by the terminal, where the method further includes: and the second AMF sends release requests to the N intermediate session management network elements, wherein the release requests are used for requesting to release session resources. And deleting the session with the access type not modified into the 5G network according to the release request by the N intermediate session management network elements, wherein the session with the access type modified into the 5G network is not deleted.

The migration of a terminal from a 4G network to a 5G network is exemplarily described below with reference to fig. 14.

Referring to fig. 14, comprising:

1401. the MME receives a migration request, wherein the migration request is used for requesting migration to the 5G network.

When the terminal migrates to the 5G network through the cell handover procedure, the migration request may be: handover Required message sent by E-UTRAN.

When the terminal migrates to the 5G network through the registration update procedure, the migration request may be: the AMF sends a Context Request message.

1402. The MME sends a relocation request to the AMF.

The relocation request comprises SGW Node Name of SGW-C of the terminal, SGW F-TEID allocated to the terminal by SGW-C of the terminal, identifier of the terminal and EPS Bearer ID of each session of the terminal in the 4G network.

When the terminal migrates to the 5G network through the cell handover procedure, the relocation request may be: the MME sends Forward Relocation Request message to the AMF.

When the terminal migrates to the 5G network through the registration update procedure, the relocation request may be: the MME sends a Context Response message to the AMF.

1403. The AMF sends a discovery request to the NRF, the discovery request requesting I-SMF discovery.

1404. The NRF returns a discovery response to the AMF.

The discovery response may include a candidate I-SMF list, where the list includes address information of one or more I-SMFs capable of providing relevant services to the terminal. I-SMF is independent I-SMF or SGW-C+I-SMF. For SGW-C+I-SMF, the discovery response also includes SGW Node Name information when SGW-C+I-SMF is used as SGW-C.

It should be noted that, the AMF may determine whether an I-SMF is SGW-c+i-SMF according to whether the I-SMF has information of a corresponding SGW Node Name. Specifically, when an I-SMF has the information of the corresponding SGW Node Name, the I-SMF is SGW-C+I-SMF. Otherwise, the I-SMF is not SGW-C+I-SMF.

In particular implementations, the NRF may determine I-SMFs that may serve the terminal based on the location of the terminal and the location area supported by the I-SMFs, and send the information of these I-SMFs to the AMF in a discovery response.

1405. The AMF selects an I-SMF for each session.

It should be noted that, the AMF may obtain a candidate I-SMF list once for each session corresponding to the SGW-C. In this case, in the specific implementation of step 1405, if the SGW Node Name of the SGW-C included in the relocation request belongs to a certain I-SMF (denoted as I-SMF 3) in the candidate I-SMF list acquired for the session 3, for each session (for example, session 3) corresponding to the SGW-C of the terminal, the AMF preferentially selects the I-SMF3 as the I-SMF of the session 3, and may set the session level SGW Change Indication identifier of the session 3 to False. If the SGW Node Name of the SGW-C included in the relocation request does not belong to a certain I-SMF in the candidate I-SMF list acquired for the session 3, the AMF preferentially selects the SGW-c+i-SMF in the candidate I-SMF list as the I-SMF of the session 3, and may also set the session level SGW Change Indication identifier of the session 3 to True.

1406. The AMF sends a relocation response to the MME, the relocation response including the terminal-level SGW Change Indication identity of the terminal. The MME records the terminal level SGW Change Indication identity of the terminal in the relocation response.

Wherein, if the session level SGW Change Indication of at least one session of the terminal is identified as False, the terminal level SGW Change Indication of the terminal is identified as False.

If the session level SGW Change Indication of all sessions of the terminal is identified as False, the terminal level SGW Change Indication of the terminal is identified as False.

When the terminal migrates to the 5G network through the cell handover procedure, the relocation response may be: the AMF sends Forward Relocation Response message to the MME.

When the terminal migrates to the 5G network through the registration update procedure, the relocation response may be: the AMF sends Context Acknowledge message to the MME.

1407. The AMF sends a context setup request to each I-SMF selected for each session of the terminal.

The context establishment request sent to one I-SMF includes the identifier of the terminal received in step 1402 and the EPS Bearer ID of the session managed by the I-SMF in the 4G network.

Optionally, for a session, if the session level SGW Change Indication of the session is identified as False, the context request may further include the SGW F-TEID allocated to the terminal by the SGW-C of the terminal received in step 1402.

For example, the context setup request may be: nsmf_pduse_ CreateSMContext Request message.

1408. Each I-SMF locates a corresponding session.

In a specific implementation, if the context request includes the SGW F-TEID allocated by the SGW-C of the terminal to the terminal, the I-SMF locates the corresponding session according to the SGW F-TEID. Otherwise, the I-SMF locates the corresponding session according to the identifier of the terminal in the context request and the EPS Bearer ID corresponding to the session.

If the I-SMF locates the corresponding session, the I-SMF modifies the access type of the corresponding session to be a 5G network.

1409. The AMF sends a release request to I-SMF 3.

Wherein the AMF may send a release request to the I-SMF3 when at least one session level SGW Change Indication is identified as True, but the terminal level SGW Change Indication is identified as False, to request release of resources of a session on the I-SMF3 where the intermediate session management network element changes. The release request may contain the identity of the terminal received in step 1402 and EPS Bearer IDs corresponding to these sessions. Optionally, the release request further includes the SGW F-TEID and the "4G session deletion identifier" allocated to the terminal by the SGW-C of the terminal received in step 1402.

Illustratively, the release request may be: nsmf_pduse_ CreateSMContext Request message.

1410. I-SMF3 sends a release response to the AMF.

In a specific implementation of step 1410, if the access type of a session corresponding to I-SMF3 is a 5G network, the I-SMF3 does not delete the session. If the access type of a certain session corresponding to the I-SMF3 is a 4G network and the release request comprises a 4G session deletion identifier, the I-SMF3 deletes the session.

Illustratively, the release response may be: nsmf_pduse_ CreateSMContext Response message.

1411. If the SGW-U used by the session 3 is I-UPF+SGW-U and the I-UPF+SGW-U can continue to provide the service for the session 3, the I-SMF3 preferably selects the originally used I-UPF+SGW-U to continue to provide the service for the session 3.

In this case, the I-SMF3 sends a session modification request to the originally used I-UPF+SGW-U. After the I-UPF+SGW-U completes the related processing according to the session modification request, a session modification response is returned to the I-SMF 3.

1412. After each I-SMF corresponding to each session of the terminal completes service processing such as interaction with the A-SMF, a context establishment response is returned to the AMF.

Wherein, the context establishment response may be: nsmf_pduse_ CreateSMContext Response message.

1413. The MME releases the relevant resources of the session.

If the terminal stage SGW Change Indication of the terminal stored in step 1406 by the MME is identified as False, the MME does not send a release request to the SGW-C of the terminal in the subsequent processing flow. Otherwise, the MME sends a release request to SGW-C of the terminal in the subsequent processing flow to request to release relevant resources of the session. If the access type of a session corresponding to the SGW-C of the terminal is modified to the 5G network, the SGW-C of the terminal does not delete the session. Otherwise, the SGW-C of the terminal deletes the session.

Illustratively, the release request may be: delete Session Request message.

Application scenario 2: absence of an N26 interface between AMF and MME

In application scenario 2, the present application provides a communication method, as shown in fig. 15, including:

1501. when the terminal needs to be migrated from the first network to the second network, a fourth mobility management network element in the second network acquires information of N intermediate session management network elements capable of providing services for the terminal in the second network.

Wherein the first network is a 5G network and the second network is a 4G network; alternatively, the first network is a 4G network and the second network is a 5G network.

1502. The fourth mobility management element obtains information of M intermediate session management elements serving the terminal in the first network from uss+udm.

1503. If the newly-built session of the terminal on the fourth mobile management network element is the first session, the fourth mobile management network element determines an intermediate session management network element corresponding to the first session according to the types of the N intermediate session management network elements and the M intermediate session management network elements, wherein the types comprise independent intermediate session management network elements and SGW-C+I-SMF.

Optionally, step 1503, when embodied, includes:

if the SGW-C+I-SMF belongs to M intermediate session management network elements and also belongs to N intermediate session management network elements, the fourth mobile management network element selects the SGW-C+I-SMF which belongs to the M intermediate session management network elements and also belongs to the N intermediate session management network elements as the intermediate session management network element corresponding to the first session;

if the M intermediate session management network elements do not include SGW-c+i-SMF, or if the M intermediate session management network elements include SGW-c+i-SMF but the SGW-c+i-SMF in the M intermediate session management network elements does not belong to the N intermediate session management network elements, the fourth mobility management network element preferentially selects the SGW-c+i-SMF in the N intermediate session management network elements as the intermediate session management network element corresponding to the first session.

And after determining the intermediate session management network element corresponding to the first session in the case that the first network is a 5G network and the second network is a 4G network, the intermediate session management network elements corresponding to other sessions in the 4G network are identical to the intermediate session management network element of the first session. If the first network is a 4G network and the second network is a 5G network, if the session newly established by the terminal on the fourth mobility management element is not the first session, the fourth mobility management element preferentially selects SGW-c+i-SMF in the intermediate session management element corresponding to the session already established by the terminal on the fourth mobility management element as the intermediate session management element corresponding to the newly established session.

In the method provided in fig. 15, in the case that the terminal needs to migrate from the first network to the second network, the SGW-c+i-SMF may be preferentially determined for the session of the terminal in the second network, so that the session of the terminal is anchored in the SGW-c+i-SMF after the network migration, thereby improving the overall communication efficiency of the network, for example, reducing the network address resources to simplify the complexity of network planning and deployment, reducing the number of nodes in the network to simplify the network operation and maintenance workload, reducing the signaling between network nodes to reduce the network traffic load, and so on.

After the terminal accesses the 5G network, the terminal may need to migrate from the 5G network to the 4G network due to cell handover or tracking area update, etc., and the migration process of the terminal from the 5G network to the 4G network is exemplarily described below through fig. 16.

1601. And the terminal sends a connection request to the MME.

The Request Type (Request Type) included in the connection Request may be "Handover", and the connection Request further includes a PDU Session identifier (PDU Session ID) allocated by the terminal for the Session (denoted as Session 5).

Illustratively, the connection request may be: PDN Connectivity Request message.

1602. The MME sends a discovery request to the DNS Server.

The relevant explanation of step 1602 may be found in step 1206.

1603. The DNS Server returns a discovery response to the MME.

The relevant explanation of step 1603 may be seen in step 1207.

1604. The MME selects SGW-C (denoted SGW-C5) for the terminal.

In a specific implementation, if session 5 is the first session established by the terminal on the MME, if in the procedure shown in fig. 8, the MME records a terminal level SGW Node Name of the terminal or a session level SGW Node Name of the session of the terminal, the MME selects one SGW-c+i-SMF for the terminal in the terminal level SGW Node Name or the session level SGW Node Name of the session of the terminal, and if in the procedure shown in fig. 8, the MME does not record the terminal level SGW Node Name of the terminal or the session level SGW Node Name of the session of the terminal, the MME selects one SGW-c+i-SMF for the terminal in the SGW-C list. If session 5 is not the first session established by the terminal on the MME, the MME selects the SGW-C already in use as SGW-C for session 5.

1605. The MME sends a session establishment request to SGW-C5.

The session establishment request may include: the identity of the terminal and the PDU Session ID information acquired in step 1601.

1606. The SGW-C5 locates the corresponding session according to the session establishment request.

The SGW-C5 may specifically locate the corresponding Session according to the identity of the terminal and the PDU Session ID in the Session establishment request.

If the SGW-C5 is selected from the terminal-level SGW Node Name of the terminal or the session-level SGW Node Name of the session of the terminal recorded by the MME, the SGW-C5 updates the session 5 according to the session establishment request, and modifies the access type of the session 5 to be the 4G network. Otherwise, the SGW-C5 establishes a new session 5 according to the session establishment request.

1607. If the I-UPF used by the session 5 in the 5G network is I-upf+sgw-U and can continue to provide services for the session 5, the SGW-C5 preferably selects the I-upf+sgw-U that was originally used to continue to provide services for the terminal.

In this case, the SGW-C5 sends a session modification request to the originally used I-UPF+SGW-U. After the I-UPF+SGW-U completes the related processing according to the session modification request, a session modification response is returned to SGW-C5.

1608. And after the SGW-C5 finishes service processing such as interaction with the PGW-C, returning a session establishment response to the MME.

1609. And after finishing the related service processing, the MME returns a connection response to the terminal.

Illustratively, the connection response may be: PDN Connectivity Response message.

1610. The a-SMF sends a session release request to the SGW-C5 for requesting release of related resources of the session in the 5G network.

Illustratively, the session release request may be: nsmf_pduse_ StatusNotify Request message.

1611. And the SGW-C5 performs message interaction of a session resource release flow with the AMF to release related resources of the session.

In a specific implementation, the SGW-C5 does not delete the corresponding session if it finds that the access type of the corresponding session has been modified to the 4G network.

1612. The SGW-C5 returns a session release response to the a-SMF.

Illustratively, the session release response may be: nsmf_pduse_ StatusNotify Response message.

After the terminal accesses the 4G network, the terminal may need to migrate from the 4G network to the 5G network due to cell handover or registration update, etc., and the migration process of the terminal from the 4G network to the 5G network is exemplarily described below through fig. 17.

Referring to fig. 17, comprising:

1701. the terminal sends a session establishment request to the AMF for requesting to establish a session.

Wherein the session establishment request may include: request Type (Request Type) and PDU Session ID assigned by the terminal for the Session (noted Session 6). The Request Type may be "Existing PDU Session".

Illustratively, the session establishment request may be: PDU Session Establishment Request message.

1702. The AMF sends a discovery request to the NRF, the discovery request requesting I-SMF discovery.

The relevant explanation of step 1702 may be seen in step 801.

1703. The NRF returns a discovery response to the AMF.

The relevant explanation of step 1703 may be seen in step 802.

1704. AMF selects I-SMF (denoted as I-SMF 6) for session 6.

In the specific implementation of step 1704, if the AMF records the terminal level SGW Node Name of the terminal, and if the terminal level SGW Node Name of the terminal belongs to the I-SMF list and the I-SMF corresponding to the terminal level SGW Node Name is SGW-c+i-SMF, the AMF preferably selects the SGW-c+i-SMF corresponding to the terminal level SGW Node Name of the terminal as the I-SMF6, or may set the session level SGW Change Indication identifier of the session 6 to False. Otherwise, the AMF selects one SGW-C+I-SMF in the I-SMF list as the I-SMF of session 6, and sets the session level SGW Change Indication identification of session 6 to True.

Further, if the session level SGW Change Indication of at least one session of the terminal is identified as False, the AMF identifies the terminal level SGW Change Indication of the terminal as False. Alternatively, if the session level SGW Change Indication of all sessions of the terminal is identified as False, the terminal level SGW Change Indication of the terminal is identified as False.

1705. The AMF sends a session context setup request to the I-SMF 6.

The Session context establishment request includes the identifier of the terminal and the PDU Session ID information.

Illustratively, the session context establishment request may be: nsmf_pduse_ CreateSMContext Request message.

1706. The I-SMF6 establishes a request to locate a corresponding session according to the session context.

Specifically, the I-SMF6 locates the corresponding Session according to the identity of the terminal and the PDU Session ID in the Session context setup request.

If the I-SMF6 is selected from the terminal level SGW Node Name of the terminal recorded in the AMF, the I-SMF6 updates the session 6 according to the session establishment request, and modifies the access type of the session 6 to be a 5G network. Otherwise, the I-SMF6 establishes a new session 6 according to the session establishment request.

1707. If the SGW-U used by the session 6 is I-UPF+SGW-U and the I-UPF+SGW-U can continue to provide service for the session 6, the I-SMF6 preferably selects the originally used I-UPF+SGW-U to continue to provide service for the session 6.

In this case, the I-SMF6 sends a session modification request to the originally used I-UPF+SGW-U. After the I-UPF+SGW-U completes the related processing according to the session modification request, a session modification response is returned to the I-SMF 6.

1708. The AMF sends a release request to the I-SMF 6.

Wherein the AMF may send a release request to the I-SMF6 when at least one session level SGW Change Indication is identified as True, but the terminal level SGW Change Indication is identified as False, to request release of related resources of a session on the I-SMF6 where the intermediate session management network element changes. The release request may contain the identity of the terminal and EPS Bearer IDs corresponding to these sessions. Optionally, the release request further includes an SGW F-TEID and a "4G session deletion identifier" allocated by the SGW-C of the terminal to the terminal.

1709. I-SMF6 sends a release response to the AMF.

In a specific implementation, if the access type of a session corresponding to the I-SMF6 is a 5G network, the I-SMF6 does not delete the session. If the access type of a certain session corresponding to the I-SMF6 is a 4G network and the release request comprises a 4G session deletion identifier, the I-SMF6 deletes the session.

1710. After the I-SMF6 completes the service processing such as interaction with the PGW-C, a session context establishment response is returned to the AMF.

Illustratively, the session context setup response may be: nsmf_pduse_ CreateSMContext Response response message.

1711. After the AMF completes the processing of the related service, a session establishment response is returned to the terminal.

Illustratively, the session establishment response may be: PDU Session Establishment Accept Response message.

1712. The PGW-C sends a delete session request to the I-SMF6 requesting release of the relevant resources of the session in the 4G network.

Illustratively, the delete session request may be: delete Session Request message.

1713. And the I-SMF6 performs message interaction of a session resource release procedure with the MME and is used for releasing related resources of the session on the MME and the E-UTRAN.

In releasing the relevant resources of the session, if the access type of the session is found to have been modified to a 5G network, the session is not deleted.

1714. The I-SMF6 returns a delete session response to the PGW-C.

Illustratively, the delete session response may be: delete Session Resonpse message.

The indication information for indicating that the I-SMF is SGW-c+i-SMF in the above embodiment may be denoted as first indication information.

In the above embodiment, the I-upf+sgw-U refers to a network element that merges the I-UPF and the SGW-U, and the network element that merges the I-UPF and the SGW-U may be a network element that merges only the I-UPF and the SGW-U, or may be a network element that merges other network elements. Similarly, I-SMF+SGW-C refers to a network element that merges I-SMF and SGW-C, which may be a network element that merges only I-SMF and SGW-C, which may be a network element that merges I-SMF and SGW-C, and which also merges other network elements, e.g., where other network elements may be one or more of PGW-C and A-SMF.

The method provided by the embodiment of the application is exemplified by three aspects of I-smf+sgw-c+pgw-c+a-SMF, I-smf+sgw-c+pgw-c+a-SMF registration, intermediate session management network element selection during session establishment, and intermediate session management network element selection during network migration, and is specifically described by the fourth to sixth sections below. The description of these parts applies equally to a network element that merges I-SMF, SGW-C and PGW-C (which may be referred to as I-SMF+SGW-C+PGW-C), with the understanding that I-SMF+SGW-C+PGW-C+A-SMF is replaced by I-SMF+SGW-C+PGW-C.

Fourth part: registration of I-SMF+SGW-C+PGW-C+A-SMF

I-SMF+SGW-C+PGW-C+A-SMF needs to register with NRF when serving as SMF (I-SMF or A-SMF), and needs to be configured on DNS Server when serving as SGW-C or PGW-C.

When I-smf+sgw-c+pgw-c+a-SMF is used as the SMF, the present application provides a communication method, as shown in fig. 22, including:

2201. the SMF in the first network sends a registration request to the NRF in the first network. Accordingly, the NRF receives a registration request from the SMF.

Wherein the first network is a 5G network. The registration request includes SMF information.

When the SMF is I-SMF+SGW-C+PGW-C+A-SMF, the information of the SMF comprises second indication information, and the second indication information is used for indicating that the SMF is I-SMF+SGW-C+PGW-C+A-SMF. For example, the second indication information may be I-smf+sgw-c+pgw-c+a-SMF as PGW Node Name of PGW-C.

In FIG. 22, SMF is shown as I-SMF+SGW-C+PGW-C+A-SMF.

The SMF information also includes information such as location area and interface address supported when I-SMF+SGW-C+PGW-C+A-SMF is used as I-SMF.

2202. The NRF sends a registration response to the SMF. Accordingly, the SMF receives a registration response from the NRF.

The configuration process on the DNS Server when I-smf+sgw-c+pgw-c+a-SMF is used as SGW-C may refer to the corresponding content in the first part, and will not be described again. The process of configuring on a DNS Server when I-SMF+SGW-C+PGW-C+A-SMF is used as PGW-C is well known to those skilled in the art and will not be described in detail.

The method shown in the fourth section, I-smf+sgw-c+pgw-c+a-SMF, may be registered in NRF, and by carrying the second indication information, NRF may determine which SMFs are I-smf+sgw-c+pgw-c+a-SMF, and which SMFs are independent SMF, so as to support the subsequent SMF selection and other processes. Similarly, I-SMF+SGW-C+PGW-C+A-SMF may be configured into a DNS Server, which may determine which SGW-C are I-SMF+SGW-C+PGW-C+A-SMF and which SGW-C are independent SGW-C, thereby supporting subsequent SGW-C selection and the like.

The following exemplifies the registration procedure when I-smf+sgw-c+pgw-c+a-SMF is used as SMF and the configuration procedure when SGW-C is used, see fig. 23, including:

2301. the operator configures TAI domain name information on the DNS Server.

The specific implementation of step 2301 may be referred to above in step 401, and will not be described again.

2302. I-SMF+SGW-C+PGW-C+A-SMF sends a registration request to NRF as SMF.

The registration request includes information such as a location area and an interface address supported when the I-smf+sgw-c+pgw-c+a-SMF is used as the I-SMF, and further includes a PGW Node Name when the I-smf+sgw-c+pgw-c+a-SMF is used as the PGW-C, where the PGW Node Name indicates that the SMF has PGW-C capability, that is, indicates that the SMF is I-smf+sgw-c+pgw-c+a-SMF.

2303. The NRF saves the information in the registration request and returns a registration response to the I-SMF+SGW-C+PGW-C+A-SMF.

Step 2301 is a registration procedure of I-smf+sgw-c+pgw-c+a-SMF as SGW-C. Step 2302 and step 2303 are the registration procedure of I-smf+sgw-c+pgw-c+a-SMF as SMF. I-smf+sgw-c+pgw-c+a-SMF how to register as SGW-C and how to register as SMF, these two flows may be independent of each other.

Fifth part: selection of intermediate session management network elements during session establishment

The implementation process of the communication method provided in the fifth part is similar to the implementation process of fig. 5, and only needs to replace the SGW-c+i-SMF with I-smf+sgw-c+pgw-c+a-SMF, and the SGW Node Name of SGW-C is replaced with the PGW Node Name of PGW-C. In addition, the session level SGW Node Name information included in the registration request in step 503 may be derived by the first intermediate session management network element according to the PGW Node Name, and the deriving process may be described below. The registration request in step 503 may include both SGW Node Name and PGW Node Name. In addition, the AMF may derive the SGW Node Name of the first intermediate session management network element according to the PGW Node Name of the first intermediate session management network element, and the derivation process may be described below.

In the method provided in the fifth section, the process of selecting the intermediate session management network element for the terminal by the mobility management network element is related to whether an N26 interface exists between the AMF and the MME and the network where the AMF and the MME are currently located, and is described below through application scenario 1 and application scenario 2, respectively.

Application scenario 1: presence of N26 interface between AMF and MME

If the terminal is accessed in the 5G network, the AMF needs to select the I-SMF for the session due to the reasons of session establishment, location area change of the terminal, and the like, which is similar to the process in fig. 6, only needs to replace the SGW-c+i-SMF with the I-smf+sgw-c+pgw-c+a-SMF, and replace the SGW Node Name of the SGW-C with the PGW Node Name of the PGW-C.

The terminal is accessed in the 4G network, because of the reasons of session establishment, location area change of the terminal and the like, the MME needs to select SGW-C for the session, and the specific process can be seen in the process shown in the above-mentioned figure 7, and only needs to replace SGW-C+I-SMF with I-SMF+SGW-C+PGW-C+A-SMF for understanding, and details are omitted.

Application scenario 2: absence of an N26 interface between AMF and MME

The terminal is accessed in the 5G network, because of the reasons of session establishment, location area change of the terminal and the like, the AMF needs to select I-SMF for the session (recorded as session 3), and report terminal level SGW Node Name information (terminal level SGW Node Name information is information of SGW Node Name of SGW-C for managing the session of one terminal) or session level SGW Node Name information to HSS+UDM. The selection procedure of I-SMF in the 5G network is exemplarily described below by way of fig. 24.

Referring to fig. 24, comprising:

2401-2405: similar to 601 to 605, respectively, except that the session herein is session 3, the I-SMF selected herein may be a different I-SMF than I-SMF2, denoted herein as I-SMF3, and it is sufficient to understand that SGW-c+i-SMF therein is replaced with I-smf+sgw-c+pgw-c+a-SMF, and SGW Node Name of SGW-C is replaced with PGW Node Name of PGW-C.

In a first implementation, after step 2405, steps 2406a to 2408a are performed, and in a second implementation, after step 2405, steps 2406b to 2408b are performed.

2406a, AMF derives SGW Node Name from PGW Node Name of I-SMF 3.

The specific derivation method can be referred to below, and will not be described in detail. Of course, the SGW Node Name of the I-SMF3 may also be configured on the AMF, which is not limited in this application.

2407a, AMF sends a first message to HSS+UDM to report the SGW Node Name information of I-SMF+SGW-C+PGW-C+A-SMF corresponding to the session of the terminal to HSS+UDM.

2408a, HSS+UDM returns the first response to AMF according to the updated SGW Node Name information of the first message record.

The specific implementation of step 2407a and step 2408a are similar to steps 806a and 807a, respectively, and only need to be understood by replacing SGW-C+I-SMF with I-SMF+SGW-C+PGW-C+A-SMF.

2406b, I-SMF3 derives SGW Node Name from PGW Node Name of I-SMF 3.

The specific derivation method can be referred to below, and will not be described in detail. Of course, the SGW Node Name of the I-SMF3 may also be configured on the I-SMF3, which is not limited in this application.

2407b, I-SMF3 sends a registration request as I-SMF to HSS+UDM.

2408b, hss+udm records the information in the registration request, and returns a corresponding registration response to I-SMF 3.

After step 2408a or 2408b, steps 2409a and 2410a are performed if the MME is registered with hss+udm for the terminal, and steps 2409b and 2410b are performed if the MME is not registered with hss+udm for the terminal.

2409a, hss+udm sends a second message to MME.

2410a, MME records terminal level SGW Node Name or session level SGW Node Name according to the second message, and returns a second response to hss+udm.

2409b, MME sends registration request to hss+udm.

2410b, hss+udm sends a registration response to MME, where the registration response includes a terminal-level SGW Node Name or a session-level SGW Node Name. After receiving the registration response, the MME records information in the registration response.

Step 2409a, step 2410a, step 2409b and step 2410b are similar to step 808a, step 809a, step 808b and step 809b, respectively, and only need to be understood by replacing SGW-c+i-SMF with I-smf+sgw-c+pgw-c+a-SMF.

The terminal is accessed in the 4G network, and due to the reasons of session establishment, position area change of the terminal and the like, the MME needs to select SGW-C for the session (denoted as session 4) in a process similar to that of fig. 9, and only needs to replace SGW-C+I-SMF with I-SMF+SGW-C+PGW-C+A-SMF for understanding. In addition, after 909a or 906b, the AMF acquires the SGW Node Name, and may derive the PGW Node Name according to the received SGW Node Name, so as to determine which Node the current Node is.

Sixth section: selection of intermediate session management network elements during network migration

In the sixth section, when the terminal moves from the 5G network to the 4G network, for the I-SMF being used by the terminal, if the I-SMF is I-smf+sgw-c+pgw-c+a-SMF, the AMF derives the identification information of the SGW-C (i.e., the SGW Node Name of the SGW-C) using the PGW-C identification information (i.e., the PGW Node Name of the PGW-C) included in the I-SMF according to the rule, or the I-smf+sgw-c+pgw-c+a-SMF derives the SGW Node Name of the SGW-C using the PGW Node Name of the PGW-C according to the rule and then transmits the derived SGW Node Name to the AMF. If there is an N26 interface between the AMF and the MME, the AMF may send the SGW Node Name of the SGW-C to the MME through the N26 interface, where the latter preferably provides services for the terminal by the I-SMF. If the N26 interface does not exist between the AMF and the MME, the MME and the AMF exchange information through HSS+UDM.

In the sixth section, when the terminal moves from the 4G network to the 5G network, for the SGW-C being used by the terminal, if the SGW-C is I-smf+sgw-c+pgw-c+a-SMF and there is an N26 interface between the AMF and MME, the MME transfers the SGW Node Name of the SGW-C to the AMF through the N26 interface, and the AMF derives the PGW Node Name of the PGW-C when the SGW-C is used as the PGW Node Name of the PGW-C by using the SGW Node Name of the SGW-C, preferably the I-SMF including the PGW Node Name provides the service for the terminal. If the N26 interface does not exist between the AMF and the MME, the MME and the AMF exchange information through HSS+UDM.

Application scenario 1: presence of N26 interface between AMF and MME

In the application scenario 1, information can be directly interacted between the AMF and the MME. The selection process of the intermediate session management network element in the network migration process can be seen in fig. 10, and the SGW-c+i-SMF in the intermediate session management network element is replaced by I-smf+sgw-c+pgw-c+a-SMF for understanding.

The flow of the terminal migrating from the 5G network to the 4G network is similar to the process shown in fig. 12, except that in step 1203, the rest of the contents are understood by replacing SGW-c+i-SMF with I-smf+sgw-c+pgw-c+a-SMF.

Step 1203 is different in that in one case, the session context response message further includes the SGW Node Name when I-smf+sgw-c+pgw-c+a-SMF is used as SGW-C and the SGW F-TEID allocated to the terminal when I-smf+sgw-c+pgw-c+a-SMF is used as SGW-C. The AMF can determine whether an I-SMF is I-SMF+SGW-C+PGW-C+A-SMF according to whether the I-SMF has the information of the corresponding SGW Node Name. The SGW Node Name included in the session context response message may be derived according to a PGW Node Name carried when the SGW Node Name is registered with the NRF, and a method for deriving the SGW Node Name may be described below, which is not described herein. Of course, the SGW Node Name may also be configured in the I-SMF+SGW-C+PGW-C+A-SMF, which is not limited in this application.

In another case, the session context response message may not include the SGW Node Name, but include the PGW Node Name, and after the AMF receives the session context response message, derive the SGW Node Name according to the received PGW Node Name. Of course, the AMF may be configured with I-SMF+SGW-C+PGW-C+A-SMF as SGW Node Name when SGW-C, which is not limited in this application.

The flow of terminal migration from the 4G network to the 5G network is similar to the procedure shown in fig. 14, except that step 1402, step 1403 and step 1404 are performed, and the rest of the contents are understood by replacing SGW-c+i-SMF with I-smf+sgw-c+pgw-c+a-SMF.

Step 1402 differs in that after step 1402, the AMF derives the PGW Node Name for I-SMF+SGW-C+PGW-C+A-SMF as PGW-C from the SGW Node Name for I-SMF+SGW-C+PGW-C+A-SMF as SGW-C. Of course, the AMF may be configured with I-SMF+SGW-C+PGW-C+A-SMF as SGW Node Name when SGW-C, which is not limited in this application.

Step 1403 is different in that in the first case, the discovery request includes the SGW Node Name or the AMF derived PGW Node Name. In the second case, the discovery request includes information such as the location of the terminal.

The difference in step 1404 is that, in the case that the discovery request includes the SGW Node Name or the AMF derived PGW Node Name, the discovery response includes the address information of the I-SMF requested by the AMF. Under the condition that the discovery request comprises information such as the position of the terminal and the like, the discovery response comprises a candidate I-SMF list, the list comprises one or more pieces of address information of I-SMF capable of providing relevant services for the terminal, and for I-SMF+SGW-C+PGW-C+A-SMF, the discovery response also comprises a PGW Node Name when the discovery response is used as the PGW-C, and after the AMF receives the PGW Node Name, the I-SMF+SGW-C+PGW-C+A-SMF can be deduced as the SGW Node Name when the SGW-C is used. In the subsequent process of selecting the I-SMF, the selection may be performed based on the PGW Node Name, or may be performed based on the SGW Node Name, which is not limited in this application.

Application scenario 2: absence of an N26 interface between AMF and MME

In application scenario 2, the present application provides a communication method, and the selection process of an intermediate session management network element in the network migration process may refer to fig. 15, where the SGW-c+i-SMF is replaced with I-smf+sgw-c+pgw-c+a-SMF for understanding.

The process of migrating the terminal from the 5G network to the 4G network is similar to the process shown in fig. 16, and the SGW-c+i-SMF is replaced by I-smf+sgw-c+pgw-c+a-SMF, so as to understand the process.

The flow of terminal migration from the 4G network to the 5G network is similar to the process shown in fig. 17, except that in step 1702, step 1703 and step 1704, the rest of the contents are understood by replacing SGW-c+i-SMF with I-smf+sgw-c+pgw-c+a-SMF.

Step 1702 differs in that after step 1702, the AMF derives the PGW Node Name for I-SMF+SGW-C+PGW-C+A-SMF as PGW-C from the SGW Node Name for I-SMF+SGW-C+PGW-C+A-SMF as SGW-C. Of course, the AMF may be configured with I-SMF+SGW-C+PGW-C+A-SMF as SGW Node Name when SGW-C, which is not limited in this application.

Step 1703 is different in that in the first case, the discovery request contains an AMF derived PGW Node Name. In the second case, the discovery request includes information such as the location of the terminal.

Step 1704 is different in that, in the case where the discovery request includes the PGW Node Name derived by the AMF, the discovery response includes address information of the I-SMF of the AMF request. In the second case, the discovery response includes a candidate I-SMF list, where the list includes one or more address information of I-SMFs capable of providing related services for the terminal, and for I-smf+sgw-c+pgw-c+a-SMF, the discovery response further includes a PGW Node Name when the I-smf+sgw-c+pgw-c+a-SMF is used as the PGW Node Name, and after the AMF receives the PGW Node Name, the I-smf+sgw-c+pgw-c+a-SMF may be derived as the SGW Node Name when the SGW-C is used as the SGW Node Name. In the subsequent process of selecting the I-SMF, the selection may be performed based on the PGW Node Name, or may be performed based on the SGW Node Name, which is not limited in this application.

The following describes the derivation procedure between the SGW Node Name when I-smf+sgw-c+pgw-c+a-SMF is used as SGW-C and the PGW Node Name when PGW-C is used in the above embodiment.

According to the definition of 3GPP technical Specification (technical specification, TS) 29.303, the hostnames (Host Name or Node Name) of SGW-C and PGW-C are in the same format, and are:

<"topon"|"topoff">.<single-label-interface-name>.<canonical-node-name>。

wherein the first field < "topon" | "topoff" > indicates whether the closest node is configured and preferred topology. The first field is the same when I-SMF+SGW-C+PGW-C+A-SMF is SGW-C and PGW-C. Therefore, the first field of the PGW Node Name may be used as the first field of the SGW Node Name.

The second field < single-label-interface-name > is used to name the identity of a particular interface on a node. According to the 3GPP TS 23.003 definition, MME discovers that in the use scenario of SGW-C and PGW-C, the interface capability related to SGW-C comprises s5, s8 and s11, and the interface capability related to PGW-C comprises s5 and s8.

A set of "service-parameters" name lists for "services" defined in section 6.5 of the internet engineering task force (internet engineering task force, IETF) request for comments (request for comments, RFC) 3958 in DNS resolution are specified in 3gpp TS 23.003, as shown in table 4.9.4-1 (in this application denoted as table 2) in 3gpp TS 23.003:

Table 2 'app-service' (application service) and 'app-protocol' (application protocol) name list

Therefore, AMF or I-SMF+SGW-C+PGW-C+A-SMF may derive the second field in PGW Node Name when I-SMF+SGW-C+PGW-C+A-SMF is PGW-C as the second field in SGW Node Name when I-SMF+SGW-C+PGW-C+A-SMF is SGW-C, and vice versa, according to the interface capability defined by 3GPP above. Specifically, the interface information in the second field of the PGW Node Name is replaced with the interface information of the SGW-C, which is just required to be used as the second field of the SGW Node Name. For example, PGW-s5 in the second field of PGW Node Name is replaced with SGW-s11, or PGW-s5-s8 in the second field of PGW Node Name is replaced with SGW-s11. Specifically, the form of the interface information in the second field of the PGW Node Name is merely exemplary herein, and may be other, and is not limited. In addition, the second field of the Node Name when I-SMF+SGW-C+PGW-C+A-SMF is used as SGW-C and when PGW-C is used, can also be configured on AMF or I-SMF+SGW-C+PGW-C+A-SMF.

The third field < Canonical-node-name > is the canonical node name for the particular node. This field typically contains the physical location of the network element and the domain name (Realm). The standard format of 4G network Realm is defined in 3gpp TS 23.003, specifically: node. Eps. Nc. Node. Epc. MCC < MNC >. MCC < MCC >.3gpp network. Org. And the physical locations of PGW-C and SGW-C are the same for I-SMF+SGW-C+PGW-C+A-SMF. Therefore, the third field of the PGW Node Name may be used as the third field of the SGW Node Name.

Thus, the third field of the PGW Node Name may be considered the same when I-SMF+SGW-C+PGW-C+A-SMF is SGW-C and PGW-C. In addition, the third field of the Node Name when I-SMF+SGW-C+PGW-C+A-SMF is used as SGW-C and when PGW-C is used, can be configured on AMF or I-SMF+SGW-C+PGW-C+A-SMF.

For example, I-SMF+SGW-C+PGW-C+A-SMF may be referred to in Table 3 as SGW Node Name (i.e., SGW Host Name) for SGW-C and PGW Node Name (i.e., PGW Host Name) for PGW-C.

TABLE 3 Table 3

In summary, the I-smf+sgw-c+pgw-c+a-SMF may be configured on the AMF or I-smf+sgw-c+pgw-c+a-SMF according to the above feature, or according to a format specified by the operator, by performing conversion between the SGW Node Name when serving as SGW-C and the PGW Node Name when serving as PGW-C.

The foregoing description of the embodiments of the present application has been presented primarily from a method perspective. It will be appreciated that the respective network elements, e.g. the mobility management network element and the converged intermediate session management network element, in order to achieve the above described functionality, comprise at least one of a corresponding hardware structure and software module for performing the respective functionality. Those of skill in the art will readily appreciate that the elements and algorithm steps of the examples described in connection with the embodiments disclosed herein may be implemented as hardware or combinations of hardware and computer software. Whether a function is implemented as hardware or computer software driven hardware depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.

According to the embodiment of the application, the mobile management network element and the converged intermediate session management network element can be divided according to the method example, for example, each functional unit can be divided corresponding to each function, and two or more functions can be integrated in one processing unit. The integrated units may be implemented in hardware or in software functional units. It should be noted that, in the embodiment of the present application, the division of the units is schematic, which is merely a logic function division, and other division manners may be implemented in actual practice.

By way of example, fig. 18 shows a schematic diagram of one possible configuration of the communication device (denoted as communication device 180) involved in the above-described embodiment, the communication device 180 including a processing unit 1801. Optionally, a communication unit 1802 and/or a storage unit 1803 are also included. The structure diagram shown in fig. 18 may be used to illustrate the structure of the mobility management element or the converged intermediate session management element involved in the above embodiment.

While the schematic diagram shown in fig. 18 is used to illustrate the structure of the converged intermediate session management network element in the above embodiment, the processing unit 1801 is used to control and manage the actions of the converged intermediate session management network element, for example, the processing unit 1801 is used to perform 301 and 302 in fig. 3, 402 in fig. 4, 503 in fig. 5, 604 and 605 in fig. 6, 704 and 705 in fig. 7, 804, 805, 806b and 807b in fig. 8, 904 and 905 in fig. 9, 1209 to 1213 in fig. 12, 1409 to 1411 in fig. 14, 1605 to 1608 and 1610 and 1612 in fig. 16, 1705 to 1710 and 1712 and 1714 in fig. 17, 2201 and 2202 in fig. 22 (in this case, the converged intermediate session management network element may be I-smf+sgw-c+pgw-c+a-SMF), 2302 in fig. 23 (in this case, the converged intermediate session management network element may be I-smf+sgw-c+c-c+pgw-C), and 2404 in this case, the converged intermediate session management network element may be I-smf+sgw-C-c+c-C, and the converged intermediate session management element 2404 is performed in fig. 2. The processing unit 1801 may communicate with other network entities, for example, with the NRF in fig. 3, through the communication unit 1802. The storage unit 1803 is used to store program codes and data for fusing intermediate session management network elements.

While the schematic structure shown in fig. 18 is used to illustrate the structure of the first mobility management element according to the above embodiment, the processing unit 1801 is configured to control and manage the actions of the first mobility management element, for example, the processing unit 1801 is configured to perform actions 501 and 502 in fig. 5, 601 to 605 in fig. 6 (where the first mobility management element is an AMF), 701 to 705 in fig. 7 (where the first mobility management element is an MME), 801 to 807a in fig. 8 (where the first mobility management element is an AMF), 901 to 907 in fig. 9 (where the first mobility management element is an MME), 2401 to 2408a in fig. 24 (where the first mobility management element is an AMF), and/or actions performed by the first mobility management element in other procedures described in the embodiments of the present application. The processing unit 1801 may communicate with other network entities, such as with the I-SMF1 shown in fig. 6, via the communication unit 1802. The storage unit 1803 is configured to store program codes and data of the first mobility management element.

While the schematic structural diagram shown in fig. 18 is used to illustrate the structure of the second mobility management element according to the above embodiment, the processing unit 1801 is used to control and manage the actions of the second mobility management element, for example, the processing unit 1801 is used to perform actions 1001 and 1002 in fig. 10, 1201 to 1205 and 1208 (where the second mobility management element is an AMF) in fig. 12, 1402 to 1407 and 1409, 1410 and 1412 (where the second mobility management element is an AMF) in fig. 14, and/or actions performed by the second mobility management element in other processes described in the embodiments of the present application. The processing unit 1801 may communicate with other network entities, e.g., with the MME shown in fig. 12, via the communication unit 1802. The storage unit 1803 is configured to store program codes and data of the second mobility management element.

While the schematic structure shown in fig. 18 is used to illustrate the structure of the third mobility management element according to the above embodiment, the processing unit 1801 is configured to control and manage the actions of the third mobility management element, for example, the processing unit 1801 is configured to perform actions 1205 to 1209 and 1213 and 1214 (in this case, the third mobility management element is an MME) in fig. 12, 1401, 1402, 1406 and 1413 (in this case, the third mobility management element is an MME) in fig. 14, and/or actions performed by the third mobility management element in other procedures described in the embodiments of the present application. The processing unit 1801 may communicate with other network entities, such as with the AMF shown in fig. 12, via the communication unit 1802. The storage unit 1803 is configured to store program codes and data of the third mobility management element.

When the schematic structural diagram shown in fig. 18 is used to illustrate the structure of the fourth mobility management element according to the above embodiment, the processing unit 1801 is used to control and manage the actions of the fourth mobility management element, for example, the processing unit 1801 is used to perform the actions performed by the fourth mobility management element 1501 to 1503 in fig. 15, 1601 to 1605 and 1608 and 1609 (in this case, the fourth mobility management element is an MME), 1701 to 1705 and 1708 to 1711 (in this case, the fourth mobility management element is an AMF) in fig. 17, and/or the fourth mobility management element in other procedures described in the embodiments of the present application. The processing unit 1801 may communicate with other network entities, for example, with the terminal shown in fig. 16, through the communication unit 1802. The storage unit 1803 is configured to store program codes and data of the fourth mobility management element.

The schematic structure shown in fig. 18 may also be used to illustrate the structure of other network elements (e.g., NRF, uss+udm, DNS server, etc.) involved in the present application, where each unit in fig. 18 is used to perform an action of a corresponding network element, and specific reference may be made to the method section for understanding, which is not described herein.

The communication device 180 may be a device or a chip in the device. When the communication apparatus 180 is a device, the processing unit 1801 may be a processor or a controller, and the communication unit 1802 may be a communication interface, a transceiver circuit, a transceiver apparatus, or the like. The communication interface is a generic term and may include one or more interfaces. The storage unit 1803 may be a memory. When the communication device 180 is a chip within an apparatus, the processing unit 1801 may be a processor or a controller, and the communication unit 1802 may be an input/output interface, pins or circuits, etc. The storage unit 1803 may be a storage unit (e.g., a register, a cache, etc.) in the chip, or a storage unit (e.g., a read-only memory, a random access memory, etc.) located outside the chip in the device.

Wherein the communication unit may also be referred to as transceiver unit. The antenna and the control circuit having a transmitting and receiving function in the communication device 180 can be regarded as a communication unit 1802 of the communication device 180, and the processor having a processing function can be regarded as a processing unit 1801 of the communication device 180. Alternatively, the device for implementing the receiving function in the communication unit 1802 may be regarded as a receiving unit, where the receiving unit is configured to perform the step of receiving in the embodiment of the present application, and the receiving unit may be a receiver, a receiving circuit, or the like. The means for implementing the transmission function in the communication unit 1802 may be regarded as a transmission unit for performing the steps of transmission in the embodiments of the present application, and the transmission unit may be a transmitter, a transmission circuit, or the like.

The integrated units of fig. 18, if implemented in the form of software functional modules and sold or used as stand-alone products, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the embodiments of the present application may be essentially or a part contributing to the prior art or all or part of the technical solution may be embodied in the form of a software product stored in a storage medium, including several instructions to cause a computer device (which may be a personal computer, a server, or a network device, etc.) or a processor (processor) to perform all or part of the steps of the methods described in the embodiments of the present application. The storage medium storing the computer software product includes: a U-disk, a removable hard disk, a read-only memory (ROM), a random access memory (random access memory, RAM), a magnetic disk, or an optical disk, or other various media capable of storing program codes.

By way of example, fig. 19 also shows a schematic diagram of one possible structure of a mobility management network element (denoted mobility management network element 190) as referred to in the above embodiments, which mobility management network element 190 comprises an acquisition unit 1901 and a determination unit 1902. Optionally, a communication unit 1903 is also included. The communication unit 1903 may include a transmitting unit and/or a receiving unit.

While the schematic structural diagram shown in fig. 19 is used to illustrate the structure of the first mobility management element referred to in the above embodiment, the acquiring unit 1901 is used to perform 501 in fig. 5, the determining unit 1902 is used to perform 502 in fig. 5, and/or other actions performed by the acquiring unit 1901 and the determining unit 1902 in the process described in the embodiments of the present application. The communication unit 1903 is used for communication with other network entities, for example, with the I-SMF1 shown in fig. 6.

When the schematic structural diagram shown in fig. 19 is used to illustrate the structure of the second mobility management element referred to in the above embodiment, the acquiring unit 1901 is used to perform 1001 in fig. 10, the determining unit 1902 is used to perform 1002 in fig. 10, and/or other actions performed by the acquiring unit 1901 and the determining unit 1902 in the process described in the embodiment of the present application. The communication unit 1903 is used for communication with other network entities, for example, with the MME shown in fig. 12.

When the schematic structural diagram shown in fig. 19 is used to illustrate the structure of the fourth mobility management element related to the above embodiment, the acquiring unit 1901 is used to execute 1501 and 1502 in fig. 15, the determining unit 1902 is used to execute 1503 in fig. 15, and/or other actions executed by the acquiring unit 1901 and the determining unit 1902 in the process described in the embodiment of the present application. The communication unit 1903 is used for communication with other network entities, for example, with the terminal shown in fig. 16.

The schematic structure shown in fig. 19 may also be used to illustrate the structure of other network elements (e.g., NRF, uss+udm, DNS server, etc.) related to the present application, where each unit in fig. 19 is used to perform an action of a corresponding network element, and specific reference may be made to the method section for understanding, which is not described herein.

The units in fig. 18 and 19 may also be referred to as modules, for example, the processing unit may be referred to as a processing module, and the determination unit may be referred to as a determination module.

The embodiment of the present application further provides a schematic hardware structure of a communication device, referring to fig. 20 or fig. 21, where the communication device includes a processor 2001, and optionally, a memory 2002 connected to the processor 2001.

The processor 2001 may be a general purpose central processing unit (central processing unit, CPU), microprocessor, application-specific integrated circuit (ASIC), or one or more integrated circuits for controlling the execution of programs in accordance with aspects of the present application. The processor 2001 may also include multiple CPUs, and the processor 2001 may be a single-core (single-CPU) processor or a multi-core (multi-CPU) processor. A processor herein may refer to one or more devices, circuits, or processing cores for processing data (e.g., computer program instructions).

Memory 2002 may be a ROM or other type of static storage device, a RAM or other type of dynamic storage device that can store static information and instructions, or that can store information and instructions, or an electrically erasable programmable read-only memory (EEPROM), a CD-ROM or other optical disk storage, a compact disk storage (including compact disk, laser disk, optical disk, digital versatile disk, blu-ray disk, etc.), magnetic disk storage media or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer, as the embodiments of the present application are not limited in this regard. The memory 2002 may be provided separately, in which case the memory 2002 may be provided within the communication device or external to the communication device. Memory 2002 may also be integrated with processor 2001. Wherein the memory 2002 may include computer program code. The processor 2001 is configured to execute computer program code stored in the memory 2002, thereby implementing the methods provided by the embodiments of the present application.

In a first possible implementation, see fig. 20, the communication device further comprises a transceiver 2003. The processor 2001, memory 2002 and transceiver 2003 are connected by a bus. The transceiver 2003 is used to communicate with other devices or communication networks. Alternatively, the transceiver 2003 may include a transmitter and a receiver. The means for implementing the receiving function in the transceiver 2003 may be regarded as a receiver for performing the steps of receiving in the embodiments of the present application. The means for implementing the transmission function in the transceiver 2003 can be regarded as a transmitter for performing the steps of transmission in the embodiments of the present application.

Based on a first possible implementation, the structural diagram shown in fig. 20 may be used to illustrate the structure of the mobility management element or the converged intermediate session management element involved in the above embodiment.

While the schematic diagram shown in fig. 20 is used to illustrate the structure of the converged intermediate session management network element in the above embodiment, the processor 2001 is used to control and manage the actions of the converged intermediate session management network element, for example, the processor 2001 is used to execute 301 and 302 in fig. 3, 402 in fig. 4, 503 in fig. 5, 604 and 605 in fig. 6, 704 and 705 in fig. 7, 804, 805, 806b and 807b in fig. 8, 904 and 905 in fig. 9, 1209 to 1213 in fig. 12, 1409 to 1411 in fig. 14, 1605 to 1608 and 1610 and 1612 in fig. 16, 1705 to 1710 and 1712 and 1714 in fig. 17, 2201 and 2202 in fig. 22 (in this case, the converged intermediate session management network element may be I-smf+sgw-c+pgw-c+a-SMF), 2302 in fig. 23 (in this case, the converged intermediate session management network element may be I-smf+sgw-c+pgw-c+c-C), and 2404 in this case, the converged intermediate session management network element may be I-smf+sgw-c+c-C, and the converged intermediate session management element is performed in fig. 16, and the intermediate session management element is 2405 to 1714. Processor 2001 may communicate with other network entities, such as NRF in fig. 3, through transceiver 2003. Memory 2002 is used to store program codes and data for the converged intermediate session management network element.

While the schematic diagram shown in fig. 20 is used to illustrate the structure of the first mobility management element according to the above embodiment, the processor 2001 is used to control and manage the actions of the first mobility management element, for example, the processor 2001 is used to perform actions 501 and 502 in fig. 5, 601 to 605 in fig. 6 (where the first mobility management element is an AMF), 701 to 705 in fig. 7 (where the first mobility management element is an MME), 801 to 807a in fig. 8 (where the first mobility management element is an AMF), 901 to 907 in fig. 9 (where the first mobility management element is an MME), 2401 to 2408a in fig. 24 (where the first mobility management element is an AMF), and/or actions performed by the first mobility management element in other processes described in the embodiments of the present application. The processor 2001 may communicate with other network entities, such as with the I-SMF1 shown in fig. 6, through the transceiver 2003. Memory 2002 is used to store program codes and data for the first mobility management element.

While the schematic diagram shown in fig. 20 is used to illustrate the structure of the second mobility management element according to the above embodiment, the processor 2001 is used to control and manage the actions of the second mobility management element, for example, the processor 2001 is used to perform 1001 and 1002 in fig. 10, 1201 to 1205 and 1208 (in this case, the second mobility management element is an AMF) in fig. 12, 1402 to 1407 and 1409, 1410 and 1412 (in this case, the second mobility management element is an AMF) in fig. 14, and/or actions performed by the second mobility management element in other procedures described in the embodiments of the present application. The processor 2001 may communicate with other network entities, e.g. with the MME shown in fig. 12, through a transceiver 2003. Memory 2002 is used to store program codes and data for the second mobility management element.

While the schematic structure shown in fig. 20 is used to illustrate the structure of the third mobility management element according to the above embodiment, the processor 2001 is used to control and manage the actions of the third mobility management element, for example, the processor 2001 is used to perform the actions 1205 to 1209 and 1213 and 1214 (in this case, the third mobility management element is an MME) in fig. 12, 1401, 1402, 1406 and 1413 (in this case, the third mobility management element is an MME) in fig. 14, and/or the actions performed by the third mobility management element in other procedures described in the embodiments of the present application. Processor 2001 may communicate with other network entities, such as with the AMF shown in fig. 12, through transceiver 2003. The memory 2002 is used for storing program codes and data of the third mobility management element.

While the schematic structural diagram shown in fig. 20 is used to illustrate the structure of the fourth mobility management element according to the above embodiment, the processor 2001 is used to control and manage the actions of the fourth mobility management element, for example, the processor 2001 is used to perform the actions performed by 1501 to 1503 in fig. 15, 1601 to 1605 and 1608 and 1609 (in this case, the fourth mobility management element is MME), 1701 to 1705 and 1708 to 1711 (in this case, the fourth mobility management element is AMF) in fig. 17, and/or the fourth mobility management element in other procedures described in the embodiments of the present application. The processor 2001 may communicate with other network entities, for example, with the terminal shown in fig. 16, through the transceiver 2003. The memory 2002 is used for storing program codes and data of the fourth mobility management element.

The schematic structural diagram shown in fig. 20 may also be used to illustrate the structure of other network elements (e.g., NRF, uss+udm, DNS server, etc.) involved in the present application, where each device in fig. 20 is used to perform an action of a corresponding network element, and specific reference may be made to a method section for understanding, which is not described herein.

In a second possible implementation, the processor 2001 includes logic circuits as well as input interfaces and/or output interfaces. Wherein the output interface is for performing the act of transmitting in the respective method and the input interface is for performing the act of receiving in the respective method.

Based on a second possible implementation, referring to fig. 21, the structural diagram shown in fig. 21 may be used to illustrate the structure of the mobility management network element or the converged intermediate session management network element involved in the above embodiment.

While the schematic diagram shown in fig. 21 is used to illustrate the structure of the converged intermediate session management network element in the above embodiment, the processor 2001 is used to control and manage the actions of the converged intermediate session management network element, for example, the processor 2001 is used to execute 301 and 302 in fig. 3, 402 in fig. 4, 503 in fig. 5, 604 and 605 in fig. 6, 704 and 705 in fig. 7, 804, 805, 806b and 807b in fig. 8, 904 and 905 in fig. 9, 1209 to 1213 in fig. 12, 1409 to 1411 in fig. 14, 1605 to 1608 and 1610 and 1612 in fig. 16, 1705 to 1710 and 1712 and 1714 in fig. 17, 2201 and 2202 in fig. 22 (in this case, the converged intermediate session management network element may be I-smf+sgw-c+pgw-c+a-SMF), 2302 in fig. 23 (in this case, the converged intermediate session management network element may be I-smf+sgw-c+pgw-c+c-C), and 2404 in this case, the converged intermediate session management network element may be performed as a PGW-c+sgw-C-c+c-C, and the converged intermediate session management element in fig. 2404 (fig. 2). The processor 2001 may communicate with other network entities through at least one of an input interface and an output interface, for example, with the NRF in fig. 3. Memory 2002 is used to store program codes and data for the converged intermediate session management network element.

While the schematic diagram shown in fig. 21 is used to illustrate the structure of the first mobility management element according to the above embodiment, the processor 2001 is used to control and manage the actions of the first mobility management element, for example, the processor 2001 is used to perform actions 501 and 502 in fig. 5, 601 to 605 in fig. 6 (where the first mobility management element is an AMF), 701 to 705 in fig. 7 (where the first mobility management element is an MME), 801 to 807a in fig. 8 (where the first mobility management element is an AMF), 901 to 907 in fig. 9 (where the first mobility management element is an MME), 2401 to 2408a in fig. 24 (where the first mobility management element is an AMF), and/or actions performed by the first mobility management element in other processes described in the embodiments of the present application. The processor 2001 may communicate with other network entities through at least one of an input interface and an output interface, for example, with the I-SMF1 shown in fig. 6. Memory 2002 is used to store program codes and data for the first mobility management element.

While the schematic diagram shown in fig. 21 is used to illustrate the structure of the second mobility management element according to the above embodiment, the processor 2001 is used to control and manage the actions of the second mobility management element, for example, the processor 2001 is used to perform 1001 and 1002 in fig. 10, 1201 to 1205 and 1208 (in this case, the second mobility management element is an AMF) in fig. 12, 1402 to 1407 and 1409, 1410 and 1412 (in this case, the second mobility management element is an AMF) in fig. 14, and/or actions performed by the second mobility management element in other procedures described in the embodiments of the present application. The processor 2001 may communicate with other network entities through at least one of an input interface and an output interface, for example, with the MME shown in fig. 12. Memory 2002 is used to store program codes and data for the second mobility management element.

While the schematic structure shown in fig. 21 is used to illustrate the structure of the third mobility management element according to the above embodiment, the processor 2001 is used to control and manage the actions of the third mobility management element, for example, the processor 2001 is used to perform the actions 1205 to 1209 and 1213 and 1214 (in this case, the third mobility management element is an MME) in fig. 12, 1401, 1402, 1406 and 1413 (in this case, the third mobility management element is an MME) in fig. 14, and/or the actions performed by the third mobility management element in other procedures described in the embodiments of the present application. The processor 2001 may communicate with other network entities through at least one of an input interface and an output interface, for example, with the AMF shown in fig. 12. The memory 2002 is used for storing program codes and data of the third mobility management element.

While the schematic diagram shown in fig. 21 is used to illustrate the structure of the fourth mobility management element according to the above embodiment, the processor 2001 is used to control and manage the actions of the fourth mobility management element, for example, the processor 2001 is used to perform the actions performed by 1501 to 1503 in fig. 15, 1601 to 1605 and 1608 and 1609 (in this case, the fourth mobility management element is MME), 1701 to 1705 and 1708 to 1711 (in this case, the fourth mobility management element is AMF) in fig. 17, and/or the fourth mobility management element in other procedures described in the embodiments of the present application. The processor 2001 may communicate with other network entities through at least one of an input interface and an output interface, for example, with the terminal shown in fig. 16. The memory 2002 is used for storing program codes and data of the fourth mobility management element.

The schematic structure shown in fig. 21 may also be used to illustrate the structure of other network elements (e.g., NRF, uss+udm, DNS server, etc.) related to the present application, where each device in fig. 21 is used to perform an action of a corresponding network element, and specific reference may be made to a method section for understanding, which is not described herein.

Embodiments of the present application also provide a computer-readable storage medium comprising instructions that, when run on a computer, cause the computer to perform any of the methods described above.

Embodiments of the present application also provide a computer program product comprising instructions which, when run on a computer, cause the computer to perform any of the methods described above.

The embodiment of the application also provides a communication system, which comprises: the at least two network elements according to the embodiments of the present application, for example, the second AMF and the third MME.

In the above embodiments, it may be implemented in whole or in part by software, hardware, firmware, or any combination thereof. When implemented using a software program, it may be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the processes or functions described in accordance with embodiments of the present application are produced in whole or in part. The computer may be a general purpose computer, a special purpose computer, a computer network, or other programmable apparatus. The computer instructions may be stored in or transmitted from one computer-readable storage medium to another, for example, a website, computer, server, or data center via a wired (e.g., coaxial cable, fiber optic, digital subscriber line (digital subscriber line, DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. Computer readable storage media can be any available media that can be accessed by a computer or data storage devices including one or more servers, data centers, etc. that can be integrated with the media. The usable medium may be a magnetic medium (e.g., a floppy disk, a hard disk, a magnetic tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a Solid State Disk (SSD)), or the like.

Although the present application has been described herein in connection with various embodiments, other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed application, from a review of the figures, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the "a" or "an" does not exclude a plurality. A single processor or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Although the present application has been described in connection with specific features and embodiments thereof, it will be apparent that various modifications and combinations can be made without departing from the spirit and scope of the application. Accordingly, the specification and drawings are merely exemplary illustrations of the present application as defined in the appended claims and are considered to cover any and all modifications, variations, combinations, or equivalents that fall within the scope of the present application. It will be apparent to those skilled in the art that various modifications and variations can be made in the present application without departing from the spirit or scope of the application. Thus, if such modifications and variations of the present application fall within the scope of the claims and the equivalents thereof, the present application is intended to cover such modifications and variations.

Claims

1. A method of communication, comprising:

a first mobility management network element in a first network obtains information of N intermediate session management network elements capable of serving a terminal in the first network, wherein the N intermediate session management network elements comprise a converged intermediate session management network element, the converged intermediate session management network element can provide session management in the first network and can provide session management in a second network, and N is an integer greater than 0;

the first mobility management network element determines that the converged intermediate session management network element is a first intermediate session management network element corresponding to a first session of the terminal in the first network.

2. The method of claim 1, wherein the first network is a fifth generation 5G network and the second network is a fourth generation 4G network, the method being applied in the following scenario:

the first session is a first session established by the terminal on the first mobility management network element; or alternatively, the process may be performed,

the intermediate session management network element corresponding to the session which has been established by the terminal on the first mobility management network element is not the converged intermediate session management network element.

3. The method of claim 1, wherein the first network is a 5G network and the second network is a 4G network, wherein the first mobility management element determining that the converged intermediate session management element is a first intermediate session management element corresponding to a first session of the terminal in the first network comprises:

And under the condition that the intermediate session management network element corresponding to at least one session which is established on the first mobile management network element by the terminal is the converged intermediate session management network element, the first mobile management network element determines that the converged intermediate session management network element is the first intermediate session management network element corresponding to the first session.

4. The method of claim 1, wherein the first network is a 4G network and the second network is a 5G network, the method being applied in the following scenario:

the first session is a first session established by the terminal on the first mobility management network element.

5. The method according to any one of claims 1-4, wherein the intermediate session management network element including the indication information in the information of the N intermediate session management network elements is a converged intermediate session management network element, the method further comprising:

and the first mobility management network element determines the converged intermediate session management network element according to the indication information.

6. The method according to claim 5, wherein the indication information is a node name when the converged intermediate session management network element is an intermediate session management network element in a 4G network.

7. The method of claim 5, wherein the converged intermediate session management network element further merges anchor session management network elements in a 4G network, and wherein the indication information is a node name when the converged intermediate session management network element is used as an anchor session management network element in the 4G network.

8. A method of communication, comprising:

when a terminal needs to be migrated from a source network to a target network, a second mobile management network element in a first network acquires information of N intermediate session management network elements corresponding to a session of the terminal in the source network, wherein the information of the N intermediate session management network elements is used for indicating types of each intermediate session management network element in the N intermediate session management network elements, the types comprise converged intermediate session management network elements, and the converged intermediate session management network elements can provide session management in the first network and session management in the second network; the source network is the first network, the target network is the second network, or the source network is the second network, the target network is the first network, and N is an integer greater than 0;

And the second mobility management network element determines a second intermediate session management network element corresponding to the session of the terminal in the target network according to the types of the N intermediate session management network elements.

9. The method according to claim 8, wherein the source network is the first network, the first network is a fifth generation 5G network, the target network is the second network, the second network is a fourth generation 4G network, the second mobility management element determines a second intermediate session management element corresponding to a session of the terminal in the target network according to the type of the N intermediate session management elements, comprising:

and if the N intermediate session management network elements comprise the converged intermediate session management network element, the second mobile management network element selects the converged intermediate session management network element from the N intermediate session management network elements as a second intermediate session management network element corresponding to the session of the terminal in the second network.

10. The method according to claim 8 or 9, characterized in that the method further comprises:

the second mobility management network element sends a relocation request to a third mobility management network element in the second network, wherein the relocation request comprises information of the second intermediate session management network element and indication information, and the indication information is used for indicating the second intermediate session management network element to be a converged intermediate session management network element.

11. The method according to claim 10, wherein the indication information is a node name when the converged intermediate session management network element is an intermediate session management network element in a 4G network.

12. The method according to claim 10, wherein the converged intermediate session management network element is further converged with an anchor session management network element in a 4G network, the indication information is a node name when the converged intermediate session management network element is used as an intermediate session management network element in the 4G network, and the node name when the converged intermediate session management network element is used as an intermediate session management network element in the 4G network is associated with the node name when the converged intermediate session management network element is used as an anchor session management network element in the 4G network.

13. The method of claim 8, wherein the source network is the second network, the second network is a 4G network, the target network is the first network, the first network is a 5G network, N = 1, the method further comprising:

the second mobility management network element obtains information of M intermediate session management network elements capable of serving the terminal in the first network, wherein the information of the M intermediate session management network elements is used for indicating the type of each intermediate session management network element in the M intermediate session management network elements;

The second mobility management network element determines a second intermediate session management network element corresponding to the session of the terminal in the target network according to the types of the N intermediate session management network elements, including:

the second mobility management network element determines a second intermediate session management network element corresponding to a second session of the terminal in the first network according to the type of the N intermediate session management network elements and the type of the M intermediate session management network elements.

14. The method according to claim 13, wherein the second mobility management element determines a second intermediate session management element corresponding to a second session of the terminal in the first network according to the type of the N intermediate session management elements and the type of the M intermediate session management elements, comprising:

if the N intermediate session management network elements include a converged intermediate session management network element, and the converged intermediate session management network element belongs to the M intermediate session management network elements, the second mobility management network element preferentially selects the converged intermediate session management network element from the M intermediate session management network elements as a second intermediate session management network element corresponding to the second session; or alternatively, the process may be performed,

If the N intermediate session management network elements do not include the converged intermediate session management network element, or the N intermediate session management network elements include the converged intermediate session management network element but the converged intermediate session management network element does not belong to the M intermediate session management network elements, the second mobility management network element preferentially selects the converged intermediate session management network element from the M intermediate session management network elements as a second intermediate session management network element corresponding to the second session.

15. The method of claim 14, wherein the method further comprises:

the second mobility management network element sends a request message to the converged intermediate session management network element, wherein the request message is used for requesting the converged intermediate session management network element to update the second session; the request message contains session identification allocated by the converged intermediate session management network element for the terminal in the second network.

16. A method of communication, comprising:

a third mobility management network element in a second network receives a relocation request from a second mobility management network element in a first network, wherein the relocation request comprises information of a second intermediate session management network element and indication information, the second intermediate session management network element is an intermediate session management network element corresponding to a session of a terminal in the second network, which is determined by the second mobility management network element for the terminal, and the indication information is used for indicating the second intermediate session management network element to be a converged intermediate session management network element; the converged intermediate session management network element is capable of providing session management in the first network and session management in the second network;

The third mobility management element obtains information of M intermediate session management elements capable of serving the terminal in the second network;

and the third mobile management network element determines a converged intermediate session management network element as an intermediate session management network element corresponding to the session of the terminal in the second network according to the relocation request and the M intermediate session management network elements.

17. The method according to claim 16, wherein the indication information is a node name when the converged intermediate session management network element is an intermediate session management network element in a 4G network.

18. The method of claim 16, wherein the converged intermediate session management network element further merges anchor session management network elements in a 4G network, wherein the indication information is a node name when the converged intermediate session management network element is an intermediate session management network element in the 4G network, and wherein the node name when the converged intermediate session management network element is an intermediate session management network element in the 4G network is associated with the node name when the converged intermediate session management network element is an anchor session management network element in the 4G network.

19. The method according to any one of claims 16-18, further comprising:

If the second intermediate session management network element belongs to the M intermediate session management network elements, the third mobility management network element determines that the second intermediate session management network element is an intermediate session management network element corresponding to a session of the terminal in the second network;

and if the second intermediate session management network element does not belong to the M intermediate session management network elements, the third mobility management network element determines that one of the M intermediate session management network elements merges the intermediate session management network element into an intermediate session management network element corresponding to the session of the terminal in the second network.

20. A method of communication, comprising:

when a terminal needs to be migrated from a first network to a second network, a fourth mobility management network element in the second network acquires information of N intermediate session management network elements capable of providing services for the terminal in the second network;

the fourth mobility management network element obtains information of M intermediate session management network elements serving the terminal in the first network from a user data management network element;

if the session newly established by the terminal on the fourth mobility management network element is a first session, the fourth mobility management network element determines an intermediate session management network element corresponding to the first session according to the types of the N intermediate session management network elements and the M intermediate session management network elements, wherein the types include an independent intermediate session management network element and a converged intermediate session management network element, the converged intermediate session management network element can provide session management in the first network and can provide session management in the second network, and the independent intermediate session management network element can only provide session management in one of the first network and the second network.

21. The method of claim 20, wherein the fourth mobility management element determines an intermediate session management element corresponding to the first session based on the N intermediate session management elements and the M intermediate session management elements' types, comprising:

if the converged intermediate session management network element belongs to the M intermediate session management network elements and also belongs to the N intermediate session management network elements, the fourth mobile management network element selects the converged intermediate session management network element which belongs to the M intermediate session management network elements and also belongs to the N intermediate session management network elements as the intermediate session management network element corresponding to the first session;

if the M intermediate session management network elements do not include the converged intermediate session management network element, or the M intermediate session management network elements include the converged intermediate session management network element but the converged intermediate session management network element of the M intermediate session management network elements does not belong to the N intermediate session management network elements, the fourth mobility management network element preferentially selects the converged intermediate session management network element of the N intermediate session management network elements as the intermediate session management network element corresponding to the first session.

22. The method of claim 20 or 21, wherein the first network is a fourth generation 4G network and the second network is a fifth generation 5G network, the method further comprising:

if the newly-built session of the terminal on the fourth mobility management network element is not the first session, the fourth mobility management network element preferentially selects a converged intermediate session management network element in the intermediate session management network elements corresponding to the established session of the terminal on the fourth mobility management network element as an intermediate session management network element corresponding to the newly-built session.

23. A communication device, located in a first network, comprising:

an obtaining unit, configured to obtain information of N intermediate session management network elements capable of serving a terminal in the first network, where the N intermediate session management network elements include a converged intermediate session management network element, where the converged intermediate session management network element is capable of providing session management in the first network and capable of providing session management in a second network, and N is an integer greater than 0;

and the determining unit is used for determining the converged intermediate session management network element as a first intermediate session management network element corresponding to the first session of the terminal in the first network.

24. The apparatus of claim 23, wherein the first network is a fifth generation 5G network, the second network is a fourth generation 4G network, and the first session is a first session established by the terminal on the apparatus; or the intermediate session management network element corresponding to the session which the terminal has established on the device is not the converged intermediate session management network element.

25. The apparatus of claim 23, wherein the first network is a 5G network and the second network is a 4G network;

the determining unit is specifically configured to determine that the converged intermediate session management network element is a first intermediate session management network element corresponding to the first session when the intermediate session management network element corresponding to at least one session that has been established by the terminal on the device is the converged intermediate session management network element.

26. The apparatus of claim 23, wherein the first network is a 4G network and the second network is a 5G network, and wherein the first session is a first session established by the terminal on the apparatus.

27. A communication device, located in a first network, comprising:

An obtaining unit, configured to obtain, when a terminal needs to migrate from a source network to a target network, information of N intermediate session management network elements corresponding to a session of the terminal in the source network, where the information of the N intermediate session management network elements is used to indicate a type of each intermediate session management network element in the N intermediate session management network elements, where the type includes a converged intermediate session management network element, where the converged intermediate session management network element is capable of providing session management in the first network and is capable of providing session management in the second network; the source network is the first network, the target network is the second network, or the source network is the second network, the target network is the first network, and N is an integer greater than 0;

and the determining unit is used for determining a second intermediate session management network element corresponding to the session of the terminal in the target network according to the types of the N intermediate session management network elements.

28. The apparatus of claim 27, wherein the source network is the first network, the first network is a fifth generation 5G network, the target network is the second network, the second network is a fourth generation 4G network,

The determining unit is specifically configured to select, when the N intermediate session management network elements include a converged intermediate session management network element, the converged intermediate session management network element of the N intermediate session management network elements as a second intermediate session management network element corresponding to a session of the terminal in the second network.

29. The apparatus of claim 27, wherein the source network is the second network, the second network is a 4G network, the target network is the first network, the first network is a 5G network, and N = 1;

the acquiring unit is further configured to acquire information of M intermediate session management network elements capable of serving the terminal in the first network, where the information of the M intermediate session management network elements is used to indicate a type of each intermediate session management network element in the M intermediate session management network elements;

the determining unit is specifically configured to determine a second intermediate session management network element corresponding to a second session of the terminal in the first network according to the type of the N intermediate session management network elements and the type of the M intermediate session management network elements.

30. A communication device, located in a second network, comprising:

A communication unit, configured to receive a relocation request from a second mobility management network element in a first network, where the relocation request includes information of a second intermediate session management network element and indication information, where the second intermediate session management network element is an intermediate session management network element corresponding to a session of the terminal in the second network determined by the second mobility management network element for the terminal, and the indication information is used to indicate that the second intermediate session management network element is a converged intermediate session management network element; the converged intermediate session management network element is capable of providing session management in the first network and session management in the second network;

a processing unit, configured to obtain information of M intermediate session management network elements capable of serving the terminal in the second network;

the processing unit is further configured to determine, according to the relocation request and the M intermediate session management network elements, that one converged intermediate session management network element is an intermediate session management network element corresponding to a session of the terminal in the second network.

31. A communication device, located in a second network, comprising:

an acquiring unit, configured to acquire information of N intermediate session management network elements capable of providing services for a terminal in a second network when the terminal needs to migrate from the first network to the second network;

The acquiring unit is further configured to acquire information of M intermediate session management network elements serving the terminal in the first network from a user data management network element;

a determining unit, configured to determine, when a session newly created by the terminal on the device is a first session, an intermediate session management network element corresponding to the first session according to types of the N intermediate session management network elements and the M intermediate session management network elements, where the types include an independent intermediate session management network element and a converged intermediate session management network element, where the converged intermediate session management network element is capable of providing session management in the first network and is capable of providing session management in the second network, and where the independent intermediate session management network element is only capable of providing session management in one of the first network and the second network.

32. The apparatus of claim 31, wherein the device comprises a plurality of sensors,

the determining unit is specifically configured to select, when there is a converged intermediate session management network element that belongs to both the M intermediate session management network elements and the N intermediate session management network elements, an intermediate session management network element that belongs to both the M intermediate session management network elements and the N intermediate session management network elements as an intermediate session management network element corresponding to the first session;

The determining unit is specifically configured to, when the M intermediate session management network elements do not include a converged intermediate session management network element, or when the M intermediate session management network elements include a converged intermediate session management network element but the converged intermediate session management network element of the M intermediate session management network elements does not belong to the N intermediate session management network elements, preferentially select the converged intermediate session management network element of the N intermediate session management network elements as the intermediate session management network element corresponding to the first session.

33. A communication device, comprising: a processor;

the processor is connected to a memory for storing computer-executable instructions that the processor executes to cause the apparatus to implement the method of any one of claims 1-7.

34. A communication device, comprising: a processor;

the processor is connected to a memory for storing computer-executable instructions that the processor executes to cause the apparatus to implement the method of any one of claims 8-15.

35. A communication device, comprising: a processor;

the processor is connected to a memory for storing computer-executable instructions that the processor executes to cause the apparatus to implement the method of any one of claims 16-19.

36. A communication device, comprising: a processor;

the processor is connected to a memory for storing computer-executable instructions that the processor executes to cause the apparatus to implement the method of any one of claims 20-22.