Method and apparatus for determining a protocol data unit session service network element

Abstract

The application provides a method and device for determining a protocol data unit session service network element, which helps to control AMBR. The method comprises the following steps: a control plane function network element receives a first PDU session establishment request from a mobility management device, wherein the first PDU session establishment request comprises a first data network name (DNN); the control plane function network element determines that a PDU session corresponding to the first DNN needs to select the same control plane function network element and the same user plane function network element; and the control plane function network element sends first indication information to the mobility management device, wherein the first indication information is used for indicating that the PDU session corresponding to the first DNN needs to select the same control plane function network element.

Description

Technical Field

[0001] This application relates to the field of communications, and more specifically, to a method and apparatus for determining protocol data unit session service network elements in the field of communications. Background Technology

[0002] With the rapid development of wireless communication technology, fifth-generation (5G) mobile communication technology has emerged. In the early stages of network deployment, due to insufficient 5G network coverage, when the location of user equipment (UE) changes, the UE needs to switch between 5G and fourth-generation (4G) networks.

[0003] Establishing a packet data network (PDN) connection in a 4G network requires an access point name (APN) parameter, while creating a protocol data unit (PDU) session in 5G requires a data network name (DNN). The APN in 4G and the DNN in 5G are equivalent.

[0004] In 5G, a UE may establish one or more PDU sessions using the same DNN. Current technology does not specify how sessions with the same DNN should select a session management network element. Therefore, these one or more PDU sessions with the same DNN may choose different session management network elements. In 4G, to control the aggregated maximum bit rate (AMBR), one or more PDN connections with the same APN are required to select only one session management device. Therefore, when multiple PDU sessions with the same DNN but selected different session management network elements need to switch to the 4G network, AMBR cannot be controlled. Summary of the Invention

[0005] This application provides a method and apparatus for determining PDU session service network elements, which helps in controlling AMBR.

[0006] In a first aspect, a method for determining a PDU session service network element is provided, comprising: a control plane function network element receiving a first PDU session establishment request from a mobility management device, the first PDU session establishment request including a first data network name (DNN); the control plane function network element determining that the PDU session corresponding to the first DNN needs to select the same control plane function network element and the same user plane function network element; the control plane function network element sending first indication information to the mobility management device, the first indication information being used to indicate that the PDU session corresponding to the first DNN needs to select the same control plane function network element.

[0007] In the embodiments of this application, the control plane function network element selects the same control plane function network element and the same user plane function network element for multiple PDU sessions corresponding to the same DNN. In this way, when these multiple PDU sessions with the same DNN switch from 5G network to 4G network, they can still select the same control plane function network element and the same user plane function network element, thereby being able to control AMBR.

[0008] It should be understood that the PDU session corresponding to the first DNN refers to one or more PDU sessions that access the data network indicated by the first DNN. Specifically, the PDU session corresponding to the first DNN can be one or more PDU sessions established by a single terminal carrying the first DNN; alternatively, the PDU session corresponding to the first DNN can also be multiple PDU sessions established by different terminals carrying the first DNN.

[0009] In some implementations, the establishment request for the first PDU session also includes second indication information, which is used to indicate that the PDU session corresponding to the first DNN established by the terminal needs to select the same control plane function network element and the same user plane function network element.

[0010] Wherein, the control plane function network element determines that the PDU session corresponding to the first DNN needs to select the same control plane function network element and the same user plane function network element, including:

[0011] The control plane function network element determines, based on the second instruction information, that the PDU session corresponding to the first DNN established by the terminal needs to select the same control plane function network element and the same user plane function network element.

[0012] In other words, the second instruction information at this time is based on the terminal as the granularity, indicating that the PDU session corresponding to the first DNN established by the terminal needs to select the same control plane function network element and the same user plane function network element. In this way, multiple PDU sessions of the same DNN established by a terminal can be switched to the 4G network at the same time, which can ensure the continuity of the terminal's PDU sessions and also realize AMBR.

[0013] In some implementations, the second indication information is Session and Service Continuity (SSC) Mode 1.

[0014] In some implementations, the control plane function element determines that the PDU session corresponding to the first DNN needs to select the same control plane function element and the same user plane function element, including: the control plane function element determines that the PDU session corresponding to the first DNN needs to select the same control plane function element and the same user plane function element according to indication information, wherein the indication information is used to indicate that the PDU session corresponding to the first DNN needs to select the same control plane function element and the same user plane function element, and the indication information here can be the third indication information below, or it can be the fourth indication information.

[0015] In some implementations, the control plane function element determines that the PDU session corresponding to the first DNN needs to select the same control plane function element and the same user plane function element, including:

[0016] The control plane function network element determines, based on the third indication information, that the PDU session corresponding to the first DNN established by the terminal needs to select the same control plane function network element and the same user plane function network element. The third indication information is used to indicate that the PDU session corresponding to the first DNN established by the terminal needs to select the same control plane function network element and the same user plane function network element. The third indication information comes from the user data management network element or from the policy management network element.

[0017] In other words, the third instruction information at this time is based on the terminal as the granularity, indicating that the PDU session corresponding to the first DNN established by the terminal needs to select the same control plane function network element and the same user plane function network element. At this time, the third instruction information comes from the user data management network element or from the policy management network element.

[0018] In some implementations, the control plane function element determines that the PDU session corresponding to the first DNN needs to select the same control plane function element and the same user plane function element, including:

[0019] The control plane function network element determines, according to the fourth indication information, that the PDU session corresponding to the first DNN needs to select the same control plane function network element and the same user plane function network element. The fourth indication information is used to indicate that the PDU session corresponding to the first DNN needs to select the same control plane function network element and the same user plane function network element.

[0020] The fourth indication information comes from the policy management network element or from the control plane function network element.

[0021] In other words, the fourth indication information at this time indicates, at the DNN level, that the PDU session corresponding to the first DNN needs to select the same control plane function network element and the same user plane function network element. This fourth indication information originates from the control plane function network element itself or from the policy management network element. In this scenario, all PDU sessions within the same DNN can be simultaneously switched to the 4G network, improving handover efficiency and enabling AMBR (Advanced Mobile Broadcasting).

[0022] In some implementations, before the control plane function network element determines that the PDU session corresponding to the first DNN needs to select the same control plane function and the same user plane function network element, the method further includes: the control plane function network element determining that the first PDU session subsequently needs to be switched to the evolved packet core network (EPC).

[0023] Optionally, the control plane function network element can determine whether the first PDU session needs to be switched to EPC subsequently based on the SSC mode of the first PDU session. If the SSC mode of the first PDU session is mode 1, the control plane function network element determines that the first PDU session needs to be switched to EPC subsequently. If the SSC mode of the first PDU session is mode 2 or mode 3, the control plane function network element determines that the first PDU session does not need to be switched to EPC subsequently. PDU sessions corresponding to the same DNN established by a terminal have the same SSC mode; that is, once it is determined that the first PDU session established by a terminal needs to be switched to EPC subsequently, other PDU sessions carrying the first DNN established by that terminal also need to be switched to EPC subsequently.

[0024] In some implementations, after the control plane function element determines that the PDU session corresponding to the first DNN needs to select the same control plane function element and the same user plane function element, the method further includes: the control plane function element assigning a user plane function element to the first PDU session and storing the correspondence between the first DNN and the assigned user plane function element. Thus, when the control plane function element subsequently receives other PDU sessions carrying the first DNN, it can select the assigned user plane function element.

[0025] In some implementations, the method further includes: the control plane function network element receiving a second PDU session establishment request sent by the mobility management device, the second PDU session establishment request including the first DNN; the control plane function network element determining the user plane function network element of the first PDU session as the user plane function network element of the second PDU session.

[0026] In some implementations, the establishment request for the first PDU session further includes first single network slice auxiliary information (S-NSSAI); the PDU session corresponding to the first DNN is specifically a PDU session carrying the first DNN and the first S-NSSAI. The control plane function element can determine whether a PDU session carrying the first DNN and the first S-NSSAI has already been established. If a PDU session carrying the first DNN and the first S-NSSAI has already been established, the user plane function element selected by the control plane function element for the first PDU session is a user plane function element of an already established PDU session with the same first DNN and the first S-NSSAI. If no PDU session carrying the first DNN and the first S-NSSAI has been established, the control plane function element selects a user plane function element for the first PDU session according to existing technology.

[0027] Secondly, a method for determining a PDU session service network element is provided, comprising: the mobility management device receiving a second PDU session establishment request sent by a terminal, the second PDU session establishment request carrying a first data network name (DNN); the mobility management device determining a first control plane function network element as the control plane function network element of the second PDU session according to a first correspondence set, the first correspondence set being used to indicate that multiple PDU sessions carrying a specific DNN need to select the same specific control plane function network element; wherein, the first correspondence set includes the correspondence between the first DNN and the first control plane function network element; and the mobility management device sending the second PDU session establishment request to the first control plane function network element.

[0028] In this embodiment of the application, the mobility management device stores a first set of correspondences. When the mobility management device receives a second PDU session, it can query the first set of correspondences based on the DNN carried in the second PDU session. When the correspondence related to the DNN carried by the second PDU session is found, it is determined that the second PDU session needs to select the control plane function network element specified in the correspondence. In this way, PDU sessions with the same DNN can select the same control plane function network element.

[0029] In some implementations, the method further includes: the mobility management device receiving first indication information from the first control plane function network element, the first indication information being used to indicate that the PDU session corresponding to the first DNN needs to select the same control plane function network element; the mobility management device saving the correspondence between the first DNN and the first control plane function network element according to the first indication information.

[0030] Optionally, the mobility management device can receive first indication information sent by each of the multiple control plane functional network elements, thereby forming a first set of correspondences and storing it.

[0031] In some implementations, each element (correspondence) in the first set of correspondences is used to indicate whether a DNN corresponds to a control plane function element and whether the PDU session corresponding to a DNN needs to select the same control plane function element.

[0032] In some implementations, the establishment request for the second PDU session also includes the first single network slice auxiliary information S-NSSAI; the PDU session corresponding to the first DNN is specifically a PDU session carrying the first DNN and the first S-NSSAI.

[0033] In some implementations, the first mapping set is specifically used to indicate that multiple PDU sessions carrying a specific DNN and a specific S-NSSAI need to select the same specific control plane function element. The mobility management device searches in the first mapping set. When it finds a mapping related to the first DNN and the first S-NSSAI carried by the second PDU session, it determines that the second PDU session needs to select the control plane function element specified in the mapping set. In this way, PDU sessions with the same DNN and the same S-NSSAI can select the same control plane function element. In some implementations, the method further includes: the mobility management device receiving first indication information from the first control plane function element, the first indication information specifically used to indicate that the PDU sessions corresponding to the first DNN and the first S-NSSAI need to select the same control plane function element; the mobility management device saves the mapping relationship between the first DNN, S-NSSAI, and the first control plane function element according to the first indication information.

[0034] In some implementations, the establishment request for the second PDU session includes fifth indication information, which indicates that the PDU session corresponding to the first DNN needs to select the same user plane function network element. In a third aspect, a method for determining a PDU serving network element is provided, comprising: the mobility management device receiving a first PDU session establishment request sent by a terminal, the first PDU session establishment request including a first data network name (DNN); the mobility management device determining that the PDU session corresponding to the first DNN needs to select the same control plane function network element, or needs to select both the same control plane function network element and the same user plane function network element; and the mobility management device determining that the first control plane function network element is the control plane function network element of the first PDU session.

[0035] In some implementations, the mobility management device determines whether a PDU session with the same DNN has already been established; if a PDU session with the same DNN has already been established, the first control plane function element is the control plane function element of the established PDU session with the same DNN.

[0036] In some implementations, the establishment request of the first PDU session includes second indication information. The second indication information is used to indicate that the PDU session corresponding to the first DNN established by the terminal needs to select the same control plane function network element, or needs to select the same control plane function network element and the same user plane function network element. The mobility management device determines that the PDU session corresponding to the first DNN needs to select the same control plane function network element, or needs to select the same control plane function network element and the same user plane function network element, including: the mobility management device determines, according to the second indication information, that the PDU session corresponding to the first DNN established by the terminal needs to select the same control plane function network element, or needs to select the same control plane function network element and the same user plane function network element.

[0037] In some implementations, the second indication information is Session and Service Continuity (SSC) Mode 1.

[0038] In some implementations, the mobility management device determines that the PDU session corresponding to the first DNN needs to select the same control plane function network element, or needs to select the same control plane function network element and the same user plane function network element, including: the mobility management device determines, based on third indication information, that the PDU session corresponding to the first DNN established by the terminal needs to select the same control plane function network element, or needs to select the same control plane function network element and the same user plane function network element; the third indication information is used to indicate that the PDU session corresponding to the first DNN established by the terminal needs to select the same control plane function network element, or needs to select the same control plane function network element and the same user plane function network element; wherein, the third indication information comes from the user data management network element or from the policy management network element.

[0039] In some implementations, the mobility management device determines that the PDU session corresponding to the first DNN needs to select the same control plane function network element, or needs to select the same control plane function network element and the same user plane function network element, including: the mobility management device determines, based on fourth indication information, that the PDU session corresponding to the first DNN needs to select the same control plane function network element, or needs to select the same control plane function network element and the same user plane function network element; the fourth indication information is used to indicate that the PDU session corresponding to the first DNN needs to select the same control plane function network element, or needs to select the same control plane function network element and the same user plane function network element; wherein, the fourth indication information comes from the policy management network element or from the mobility management network element.

[0040] In some implementations, if the mobility management device determines that the PDU session corresponding to the first DNN needs to select the same control plane function network element and the same user plane function network element, the method further includes: the mobility management device sending fifth indication information to the first control plane function network element, the fifth indication information being used to indicate that the PDU session corresponding to the first DNN corresponds to the same user plane function network element.

[0041] In some implementations, the first PDU session is the first PDU session established by the terminal carrying the first DNN, or the first PDU session is a non-first PDU session established by the terminal carrying the first DNN.

[0042] In some implementations, the establishment request for the first PDU session may also include the first single network slice auxiliary information S-NSSAI; the PDU session corresponding to the first DNN is specifically a PDU session carrying the first DNN and the first S-NSSAI.

[0043] In some implementations, the mobility management device determines whether a PDU session carrying the first DNN and the first S-NSSAI has already been established. If a PDU session carrying the first DNN and the first S-NSSAI has already been established, the first control plane function element is the control plane function element of the already established PDU session with the same first DNN and first S-NSSAI. If no PDU session carrying the first DNN and the first S-NSSAI has been established, the mobility management device selects the first control plane function element for the first PDU session according to existing technology.

[0044] Thirdly, a method for determining the PDU session service network element is provided. The method includes: a mobility management device receiving a first PDU session establishment request sent by a terminal, the first PDU session establishment request including a first data network name (DNN); the mobility management device determining that the PDU session corresponding to the first DNN needs to select the same control plane function network element, or needs to select the same control plane function network element and the same user plane function network element; and the mobility management device determining the first control plane function network element as the control plane function network element of the first PDU session.

[0045] In some implementations, the method further includes: the mobility management device determining whether a PDU session with the same first DNN has already been established; if a PDU session with the same first DNN has already been established, the first control plane function network element is the control plane function network element of the established PDU session with the same first DNN.

[0046] In some implementations, the establishment request for the first PDU session includes second indication information. The second indication information is used to indicate that the PDU session corresponding to the first DNN established by the terminal needs to select the same control plane function network element, or needs to select the same control plane function network element and the same user plane function network element. The mobility management device determines that the PDU session corresponding to the first DNN needs to select the same control plane function network element, or needs to select the same control plane function network element and the same user plane function network element, including: the mobility management device determines, according to the second indication information, that the PDU session corresponding to the first DNN established by the terminal needs to select the same control plane function network element, or needs to select the same control plane function network element and the same user plane function network element.

[0047] In some implementations, the second instruction information is Session and Service Continuity (SSC) Mode 1.

[0048] In some implementations, the mobility management device determines that the PDU session corresponding to the first DNN needs to select the same control plane function network element, or needs to select the same control plane function network element and the same user plane function network element. This includes: the mobility management device determining, based on a first correspondence set and the first DNN, that the PDU session corresponding to the first DNN needs to select the same control plane function network element, or needs to select the same control plane function network element and the same user plane function network element; wherein, the first correspondence set is used to indicate that the establishment requests of multiple PDU sessions carrying a specific DNN need to select the same specific control plane function network element; wherein, the first correspondence set includes the correspondence between the first DNN and the first control plane function network element.

[0049] In some implementations, the method further includes: the mobility management device receiving first indication information from a first control plane function network element, the first indication information being used to indicate that the PDU session corresponding to the first DNN needs to select the same control plane function network element; the mobility management device saving the correspondence between the first DNN and the first control plane function network element according to the first indication information.

[0050] In some implementations, if the mobility management device determines that the PDU session corresponding to the first DNN needs to select the same control plane function network element and the same user plane function network element, the method further includes: the mobility management device sending a fifth indication information to the first control plane function network element, the fifth indication information being used to indicate that the PDU session corresponding to the first DNN needs to select the same user plane function network element.

[0051] In some implementations, the establishment request for the first PDU session also includes the first single network slice auxiliary information S-NSSAI; the PDU session corresponding to the first DNN is specifically a PDU session carrying the first DNN and the first S-NSSAI.

[0052] In some implementations, the method further includes: the mobility management device determining whether a PDU session carrying the first DNN and the first S-NSSAI has already been established; if a PDU session carrying the first DNN and the first S-NSSAI has already been established, the first control plane function network element is the control plane function network element of the established PDU session with the same first DNN and the first S-NSSAI.

[0053] Fourthly, a method for determining a PDU session service network element is provided, comprising: a control plane function network element receiving a first PDU session establishment request sent by a mobility management device, the first PDU session establishment request including a first data network name (DNN); the control plane function network element determining that the PDU session corresponding to the first DNN needs to select the same user plane function network element; and the control plane function network element determining that the first user plane function network element is the user plane function network element of the first PDU session.

[0054] In some implementations, the method further includes: the control plane function network element determining whether a PDU session with the same first DNN has already been established; if a PDU session with the same first DNN has already been established, the first user plane function network element is the user plane function network element with the established PDU session having the same first DNN.

[0055] In some implementations, the establishment request of the first PDU session includes second indication information, which is used to indicate that the PDU session corresponding to the first DNN established by the terminal needs to select the same user plane function network element; wherein, the control plane function network element determines that the PDU session corresponding to the first DNN needs to select the same user plane function network element, including: the control plane function network element determines that the PDU session corresponding to the first DNN needs to select the same user plane function network element according to the second indication information.

[0056] In some implementations, the second indication information is Session and Service Continuity (SSC) Mode 1.

[0057] In some implementations, the control plane function network element determines that the PDU session corresponding to the first DNN needs to select the same user plane function network element, including: the control plane function network element determines, according to third indication information, that the PDU session corresponding to the first DNN established by the terminal needs to select the same user plane function network element, wherein the third indication information is used to indicate that the PDU session corresponding to the first DNN established by the terminal needs to select the same user plane function network element; wherein the third indication information comes from the user data management network element or from the policy management network element.

[0058] In some implementations, the control plane function network element determines that the PDU session corresponding to the first DNN needs to select the same user plane function network element, including: the control plane function network element determines that the PDU session corresponding to the first DNN needs to select the same user plane function network element according to fourth indication information, wherein the fourth indication information is used to indicate that the PDU session corresponding to the first DNN needs to select the same user plane function network element; wherein the fourth indication information comes from the policy management network element or from the control plane function network element.

[0059] In some implementations, the establishment request for the first PDU session may also include the first single network slice auxiliary information S-NSSAI; the PDU session corresponding to the first DNN is specifically a PDU session carrying the first DNN and the first S-NSSAI.

[0060] In some implementations, the method further includes: the control plane function element determining whether a PDU session carrying the first DNN and the first S-NSSAI has already been established; if a PDU session carrying the first DNN and the first S-NSSAI has already been established, the first user plane function element is a user plane function element that has already established a PDU session with the same first DNN and the first S-NSSAI.

[0061] In some implementations, before the control plane function element determines that the PDU session corresponding to the first DNN needs to select the same control plane function element and the same user plane function element, the method further includes: the control plane function element determining that the first PDU session subsequently needs to be switched to the evolved packet core network (EPC).

[0062] Fifthly, an apparatus for determining a PDU session service network element is provided, for performing the method in the first aspect or any possible implementation thereof. Specifically, the apparatus includes a unit for performing the method in the first aspect or any possible implementation thereof.

[0063] In a sixth aspect, an apparatus for determining a PDU session service network element is provided, for performing the method in the second aspect or any possible implementation thereof. Specifically, the apparatus includes a unit for performing the method in the second aspect or any possible implementation thereof.

[0064] In a seventh aspect, an apparatus for determining a PDU session service network element is provided, for performing the method in the third aspect or any possible implementation thereof. Specifically, the apparatus includes a unit for performing the method in the third aspect or any possible implementation thereof.

[0065] Eighthly, an apparatus for determining a PDU session service network element is provided, for performing the method in the fourth aspect or any possible implementation thereof. Specifically, the apparatus includes a unit for performing the method in the fourth aspect or any possible implementation thereof.

[0066] A ninth aspect provides an apparatus for determining a PDU session service network element, the apparatus comprising: a transceiver (which may include a transmitter and a receiver), a memory, and a processor. The transceiver, the memory, and the processor communicate with each other via an internal connection path. The memory stores instructions, and the processor executes the instructions stored in the memory to control the receiver to receive signals and to control the transmitter to send signals, causing the apparatus to perform the method of the first aspect or any possible implementation thereof.

[0067] A tenth aspect provides an apparatus for determining a PDU session service network element, the apparatus comprising: a transceiver (which may include a transmitter and a receiver), a memory, and a processor. The transceiver, the memory, and the processor communicate with each other via an internal connection path. The memory stores instructions, and the processor executes the instructions stored in the memory to control the receiver to receive signals and to control the transmitter to send signals, causing the apparatus to perform the method of the second aspect or any possible implementation thereof.

[0068] Eleventhly, an apparatus for determining a PDU session service network element is provided. The apparatus includes a transceiver (which may include a transmitter and a receiver), a memory, and a processor. The transceiver, the memory, and the processor communicate with each other via an internal connection path. The memory stores instructions, and the processor executes the instructions stored in the memory to control the receiver to receive signals and to control the transmitter to send signals, causing the apparatus to perform the method of the third aspect or any possible implementation thereof.

[0069] In a twelfth aspect, an apparatus for determining a PDU session service network element is provided. The apparatus includes a transceiver (which may include a transmitter and a receiver), a memory, and a processor. The transceiver, the memory, and the processor communicate with each other via an internal connection path. The memory stores instructions, and the processor executes the instructions stored in the memory to control the receiver to receive signals and to control the transmitter to send signals, causing the apparatus to perform the method of the fourth aspect or any possible implementation thereof.

[0070] In a thirteenth aspect, a system for determining PDU session service network elements is provided, comprising the means of the fifth aspect or any optional implementation thereof and the means of the sixth aspect or any optional implementation thereof. Optionally, the system includes the means of the seventh aspect or any optional implementation thereof and the means of the eighth aspect or any optional implementation thereof. Optionally, the system includes the means of the ninth aspect or any optional implementation thereof and the means of the tenth aspect or any optional implementation thereof. Optionally, the system includes the means of the eleventh aspect or any optional implementation thereof and the means of the twelfth aspect or any optional implementation thereof.

[0071] In a fourteenth aspect, a computer-readable storage medium is provided, wherein instructions are stored therein, which, when executed on a computer, cause the computer to perform a method as described in the first aspect or any possible implementation thereof.

[0072] In a fifteenth aspect, a computer-readable storage medium is provided, wherein instructions are stored therein, which, when executed on a computer, cause the computer to perform the methods as described in the second aspect or any possible implementation thereof.

[0073] In a sixteenth aspect, a computer-readable storage medium is provided, wherein instructions are stored therein, which, when executed on a computer, cause the computer to perform the methods as described in the third aspect or any possible implementation thereof.

[0074] In a seventeenth aspect, a computer-readable storage medium is provided, wherein instructions are stored therein, which, when executed on a computer, cause the computer to perform a method as described in the fourth aspect or any possible implementation thereof.

[0075] In an eighteenth aspect, this application provides a computer program product containing instructions that, when run on a computer, cause the computer to perform the method described in the first aspect or any possible implementation thereof.

[0076] In a nineteenth aspect, this application provides a computer program product containing instructions that, when run on a computer, cause the computer to perform the methods in the second aspect or any possible implementation thereof.

[0077] In a twentieth aspect, this application provides a computer program product containing instructions that, when run on a computer, cause the computer to perform the methods in the third aspect or any possible implementation thereof.

[0078] In a twentieth aspect, this application provides a computer program product containing instructions that, when run on a computer, cause the computer to perform the methods in the fourth aspect or any possible implementation thereof.

[0079] In a twentieth aspect, this application provides a chip for determining a PDU session service network element, wherein instructions are stored that, when running on a control plane function network element or mobility management device, cause the control plane function network element or mobility management device to perform any of the methods described in the foregoing aspects. Attached Figure Description

[0080] Figure 1 This is a schematic diagram of the 4G and 5G network interconnection architecture system provided in the embodiments of this application.

[0081] Figure 2 This is a schematic diagram of the method for determining PDU session service network elements provided in the embodiments of this application.

[0082] Figure 3 This is a schematic diagram of another method for determining PDU session service network elements provided in an embodiment of this application.

[0083] Figure 4 This is a schematic diagram of another method for determining PDU session service network elements provided in an embodiment of this application.

[0084] Figure 5 This is a schematic diagram of another method for determining PDU session service network elements provided in the embodiments of this application.

[0085] Figure 6This is a schematic diagram of another method for determining PDU session service network elements provided in the embodiments of this application.

[0086] Figure 7 This is a schematic block diagram of the apparatus for determining PDU session service network elements provided in the embodiments of this application.

[0087] Figure 8 This is a schematic block diagram of another device for determining PDU session service network elements provided in the embodiments of this application.

[0088] Figure 9 This is a schematic block diagram of another device for determining PDU session service network elements provided in the embodiments of this application.

[0089] Figure 10 This is a schematic block diagram of another device for determining PDU session service network elements provided in the embodiments of this application.

[0090] Figure 11 This is a schematic block diagram of a system for determining PDU session service network elements provided in the embodiments of this application.

[0091] Figure 12 This is a schematic block diagram of another system for determining PDU session service network elements provided in the embodiments of this application.

[0092] Figure 13 This is a schematic block diagram of another device for determining PDU session service network elements provided in the embodiments of this application.

[0093] Figure 14 This is a schematic block diagram of another device for determining PDU session service network elements provided in the embodiments of this application.

[0094] Figure 15 This is a schematic block diagram of another device for determining PDU session service network elements provided in the embodiments of this application.

[0095] Figure 16 This is a schematic block diagram of another device for determining PDU session service network elements provided in the embodiments of this application. Detailed Implementation

[0096] To facilitate understanding of the technical solutions of the embodiments of this application, a brief introduction to the relevant technologies of this application is given below.

[0097] Embodiments of the present invention provide a mobility management method, which can be applied to, for example... Figure 1 In the 4G and 5G network interoperability architecture system 100 shown, such as Figure 1As shown, this includes the user plane function (UPF) shared by 4G and 5G networks, the PDN gateway user plane function (PGW-U), the session management function (SMF), the PDN gateway control plane function (PGW-C), the policy control function (PCF), the policy and charging rules function (PCRF), the home subscriber server (HSS), and the unified data management (UDM). Here, "+" indicates co-location. UPF represents the user plane function of the 5G network, PGW-U is the gateway user plane function of the 4G network corresponding to UPF, SMF is the session management function of the 5G network, PGW-C is the gateway control plane function of the 4G network corresponding to SMF, PCF is the policy control function of the 5G network, and PCRF is the policy and charging rules function of the 4G network corresponding to PCF. Here, "co-location" refers to a single device simultaneously possessing the functions of two entities. In this embodiment, for ease of description, the HSS+UDM entity is referred to as the User Data Management network element, the PGW-C entity+SMF entity as the Control Plane Functional Network element, and the UPF entity+PGW-U entity as the User Plane Functional Network element. This is a consistent explanation and will not be repeated below. Of course, the network device after the above co-location can also use other names, and this embodiment does not specifically limit this.

[0098] In addition, such as Figure 1As shown, the aforementioned 4G and 5G network interoperability architecture may also include a Mobility Management Entity (MME) and a Serving Gateway (SGW), as well as an Access and Mobility Management Function (AMF) entity in the 5G network. Specifically, terminals access the 4G network through evolved universal terrestrial radio access network (E-UTRAN) equipment, and access the 5G network through next-generation radio access network (NG-RAN) equipment. The E-UTRAN equipment communicates with the MME via the S1-MME interface, with the SGW via the S1-U interface, with the SGW via the S11 interface, with the User Data Management Entity via the S6a interface, with the AMF entity via the N26 interface, with the PGW-U entity + UPF entity via the S5-U interface, with the PGW-C entity + SMF entity via the S5-C interface, and with the NG-RAN equipment via the N3 interface. The N4 interface communicates with the PGW-C entity + SMF entity. The PGW-C entity + SMF entity communicates with the PCRF entity + PCF entity via the N7 interface. The HSS + UDM entity communicates with the PGW-C entity + SMF entity via the N10 interface. The HSS + UDM entity communicates with the AMF entity via the N8 interface. The PCRF entity + PCF entity communicates with the AMF entity via the N15 interface. The PGW-C entity + SMF entity communicates with the AMF entity via the N11 interface. The AMF entity communicates with the NG-RAN equipment via the N2 interface and with the terminal via the N1 interface. In the above interoperability architecture, the N26 interface between the MME and AMF may not exist in some scenarios. This N26 interface can be used for terminal context passing and handover processes. This application will describe the possible implementations for whether or not the N26 interface exists between the MME and AMF.

[0099] It should be noted that, Figure 1 Taking the terminal as the UE as an example, Figure 1 The interface names between the various network elements are just examples. In actual implementations, the interface names may be different. This application does not specifically limit this.

[0100] It should be noted that NG-RAN equipment in a 5G network can also be called access equipment. This access equipment refers to equipment that accesses the core network, such as base stations, broadband network gateways (BNGs), aggregation switches, and non-3GPP access equipment. Base stations can include various forms, such as macro base stations, micro base stations (also known as small stations), relay stations, and access points. This application embodiment does not specifically limit these types.

[0101] Of course, 4G and 5G networks can also include other network elements. For example, 4G networks can also include Serving GPRS Support Node (SGSN), and 5G networks can also include Authentication Server Function (AUSF) and Network Slice Selection Function (NSSF) entities. This application does not specifically limit these.

[0102] The terminals involved in the embodiments of this application may include various handheld devices, vehicle-mounted devices, wearable devices, computing devices, or other processing devices connected to a wireless modem with wireless communication capabilities; they may also include subscriber units, cellular phones, smartphones, wireless data cards, personal digital assistant (PDA) computers, tablet computers, wireless modems, handheld devices, laptop computers, cordless phones, wireless local loop (WLL) stations, machine-type communication (MTC) terminals, user equipment (UE), mobile stations (MS), terminal devices, etc. For ease of description, the devices mentioned above are collectively referred to as terminals in this application.

[0103] APN:

[0104] In a 4G network, when a terminal initiates a packet service, it can provide an Access Point Name (APN) to the Management Module (MME). Based on the APN provided by the terminal, the MME performs domain name resolution through a domain name server (DNS) to obtain the address of the session management network element (e.g., the Internet Protocol address), thereby connecting the terminal to the PDN corresponding to the APN.

[0105] DNN:

[0106] In a 5G network, when a terminal initiates a PDU session, it can provide the AMF with S-NSSAI and DNN. The AMF determines the address of the session management network element based on the S-NSSAI, DNN, and other information (such as the terminal's subscription information and local operator policies). The determined session management network element then establishes a PDU session for the terminal based on the S-NSSAI and DNN.

[0107] In 4G networks, the APN is equivalent to the DNN in 5G networks. In order to control the AMBR, in this embodiment of the application, the PDU sessions corresponding to the same DNN can select the same control plane function network element and the same user plane function network element. When the PDU session needs to switch from the 5G network to the 4G network, the continuity of the PDU session can be guaranteed, and the AMBR can also be controlled.

[0108] The method for determining PDU session service network elements provided in the embodiments of this application is described in detail below with reference to the accompanying drawings.

[0109] In this application embodiment, one possible application scenario is that the PDU session corresponding to the first DNN can select the same control plane function network element, or the same control plane function network element and the same user plane function network element. In another possible application scenario, the PDU session corresponding to the first DNN can be limited to PDU sessions with the same DNN and the same S-NSSAI, that is, PDU sessions with the same DNN and the same S-NSSAI can select the same control plane function network element, or the same control plane function network element and the same user plane function network element. For ease of description, the following example only illustrates that the PDU session corresponding to the first DNN can select the same control plane function network element and the same user plane function network element. The selection of the same control plane function network element, or the same control plane function network element and the same user plane function network element, is similar to the selection of the same control plane function network element and the same user plane function network element for the PDU session corresponding to the first DNN; therefore, it will not be described in detail here to avoid redundancy.

[0110] Figure 2 This application illustrates a method for determining a PDU session service network element according to an embodiment of the present application. The method 200 includes:

[0111] S210, the control plane function network element receives a request to establish a first PDU session from the mobility management device. The request to establish a first PDU session includes a first data network name (DNN). Optionally, the request to establish a first PDU session may further include at least one of the following: the session and service continuity (SSC) mode of the first PDU session, the session identifier of the first PDU session, the single network slice selection assistance information (S-NSSAI) corresponding to the first PDU session, and the terminal identifier of the terminal initiating the first PDU session.

[0112] S220, the control plane function element determines that the PDU session corresponding to the first DNN needs to select the same control plane function element and the same user plane function element.

[0113] It should be understood that the PDU session corresponding to the first DNN refers to one or more PDU sessions accessing the data network indicated by the first DNN. It should also be understood that the PDU session corresponding to the first DNN can be one or more PDU sessions initiated by a single terminal, or one or more PDU sessions initiated by different terminals; this application embodiment does not impose any limitations on this.

[0114] As an optional embodiment, after S210 and before S220, method 200 further includes: the control plane function element determining that the first PDU session needs to be subsequently switched to the evolved packet core (EPC). If it is determined that the first PDU session needs to be switched to the EPC, the control plane function element further determines whether the PDU session corresponding to the first DNN needs to select the same control plane function element and the same user plane function element. If it is determined that the first PDU session does not need to be switched to the EPC, the control plane function element can further select a user plane function element for the first PDU session according to existing technology.

[0115] In one possible implementation, the control plane function network element can determine whether a PDU session needs to be switched to EPC based on the SSC mode in the PDU session establishment request. Specifically, when a PDU session carries an SSC mode of SSC mode 1, the control plane function network element can determine that the PDU session needs to be switched to EPC; when a PDU session carries an SSC mode of SSC mode 2 or mode 3, the control plane function network element can determine that the PDU session does not need to be switched to EPC.

[0116] It can be assumed that multiple PDU sessions initiated by the same terminal carrying the same DNN have the same SSC mode. The control plane function network element can then determine whether the PDU session needs to be subsequently switched to EPC based on the SSC mode. For example, if multiple PDU sessions initiated by a terminal carrying a first DNN all have SSC mode 1, the control plane function network element can determine that the PDU session corresponding to the first DNN needs to be subsequently switched to EPC. When the SSC mode of the multiple PDU sessions carrying the first DNN is mode 2 or mode 3, the control plane function network element determines that the multiple PDU sessions carrying the first DNN do not need to be switched to EPC. The multiple PDU sessions carrying the first DNN include the first PDU session.

[0117] As an optional embodiment, it can be assumed that multiple PDU sessions initiated by the same terminal carrying the same DNN may have different S-NSSAIs, that is, the terminal may access the data network through different network slices (or network slice instances). In this scenario, the PDU session corresponding to the first DNN in S220 can be further limited to PDU sessions with the same DNN and the same S-NSSAI. The control plane function network element can select the same control plane function network element and the same user plane function network element for PDU sessions initiated by a terminal with the same DNN and the same S-NSSAI.

[0118] In S220, it can be determined that the first DNN-corresponding PDU session needs to select the same control plane function network element and the same user plane function network element through one or more of the following three methods.

[0119] In the first method, the establishment request for the first PDU session further includes second indication information. This second indication information is used to instruct the PDU session corresponding to the first DNN established by the terminal to select the same control plane function network element and the same user plane function network element. Specifically, step S220 includes: the control plane function network element determining, based on the second indication information, that the PDU session corresponding to the first DNN established by the terminal needs to select the same control plane function network element and the same user plane function network element. In this first method, there are two possible scenarios: First, the mobility management device determines that the PDU session corresponding to the first DNN established by the terminal needs to select the same control plane function network element and the same user plane function network element. For example, when the SSC mode of the first PDU session is mode 1, the mobility management device can determine that the PDU session corresponding to the first DNN established by the terminal needs to select the same control plane function network element and the same user plane function network element. Then, the mobility management device sends the second indication information to the control plane function network element to instruct the PDU session corresponding to the first DNN established by the terminal to select the same control plane function network element and the same user plane function network element. Second, the mobility management device directly sends a second indication message to the control plane function network element. In this case, the second indication message indicates that the Session and Service Continuity (SSC) of the first PDU session is in SSC mode 1. That is, the mobility management device forwards the SSC mode 1 in the establishment request of the first PDU session to the control plane function network element. After receiving the establishment request of the first PDU session, the control plane function network element, based on the SSC mode 1 carried in the establishment request, determines that the PDU session corresponding to the first DNN established by the terminal needs to select the same control plane function network element and the same user plane function network element.

[0120] The second method, S220, includes: the control plane function network element determines, according to the third indication information, that the PDU session corresponding to the first DNN established by the terminal needs to select the same control plane function network element and the same user plane function network element, wherein the third indication information is used to indicate that the PDU session corresponding to the first DNN established by the terminal needs to select the same control plane function network element and the same user plane function network element; wherein, the third indication information comes from the user data management network element or from the policy management network element.

[0121] In other words, the third indication information used to instruct the PDU session corresponding to the first DNN established by the terminal to select the same control plane function network element and the same user plane function network element can come from the UDM or the PCF. The third indication information can come from the subscription data of the UDM. For example, the third indication information in the subscription data of the UDM indicates that the PDU session initiated by the terminal carrying the first DNN needs to select the same control plane function network element and the same user plane function network element. Alternatively, the third indication information can come from the policy rules of the first DNN of the PCF.

[0122] The third method, S220, includes: the control plane function network element determines, according to the fourth indication information, that the PDU session corresponding to the first DNN needs to select the same control plane function network element and the same user plane function network element, wherein the fourth indication information is used to indicate that the PDU session corresponding to the first DNN needs to select the same control plane function network element and the same user plane function network element; wherein the fourth indication information comes from the policy management network element or from the control plane function network element.

[0123] In other words, the fourth indication information used to indicate that the PDU session corresponding to the first DNN needs to select the same control plane function element and the same user plane function element can come from the PCF or from the control plane function element itself, meaning that the control plane function element has locally configured the relevant rules for the DNN. For example, the control plane function element may configure certain specific DNNs so that the PDU sessions corresponding to them need to select the same control plane function element and the same user plane function element; while other specific DNNs may configure certain PDU sessions not to select the same control plane function element and the same user plane function element.

[0124] The difference between the second and third methods is as follows: In the second method, the third indication information indicates that the PDU session corresponding to the first DNN established by the terminal needs to select the same control plane function network element and user plane function network element. In the third method, the fourth indication information indicates that the PDU session corresponding to the first DNN needs to select the same control plane function network element and user plane function network element. That is, the third indication information is at the terminal level, while the fourth indication information is at the first DNN level. The PDU session corresponding to the first DNN can include one or more PDU sessions established by terminals corresponding to the first DNN. The sources of the indication information differ depending on the granularity. When the granularity is at the terminal level, the third indication information comes from the UDM or PCF; when the granularity is at the DNN level, the fourth indication information comes from the PCF or control plane function network element.

[0125] The above describes how the control plane function element determines that the PDU session corresponding to the first DNN needs to select the same control plane function element and the same user plane function element. In one possible implementation, the establishment request for the first PDU session includes the first DNN and the first single network slice auxiliary information (S-NSSAI). The following two methods describe how the control plane function element determines that the PDU session carrying the first DNN and the first S-NSSAI needs to select the same control plane function element and the same user plane function element.

[0126] In the first approach, the control plane function network element determines, based on third indication information, that a PDU session carrying the first DNN and the first S-NSSAI needs to select the same control plane function network element and the same user plane function network element. Specifically, the third indication information is used to instruct the terminal-initiated PDU session carrying the first DNN and the first S-NSSAI to select the same control plane function network element and the same user plane function network element. The third indication information may originate from subscription data in the user data management network element, which can instruct the terminal-initiated PDU session carrying the first DNN and the first S-NSSAI to select the same control plane function network element and the same user plane function network element.

[0127] In the second approach, the control plane function network element determines, based on the fourth indication information, that the PDU session carrying the first DNN and the first S-NSSAI needs to select the same control plane function network element and the same user plane function network element. The fourth indication information is used to indicate that the PDU session corresponding to the first DNN needs to select the same control plane function network element and the same user plane function network element. The fourth indication information comes from the policy management network element or from the control plane function network element.

[0128] In other words, the fourth indication information used to indicate that a PDU session carrying the first DNN and the first S-NSSAI needs to select the same control plane function element and the same user plane function element can come from the PCF or from the control plane function element itself; that is, the control plane function element has locally configured the relevant rules for DNN and S-NSSAI. For example, the control plane function element may configure that PDU sessions carrying certain specific DNNs and specific S-NSSAIs need to select the same control plane function element and the same user plane function element; while PDU sessions carrying other specific DNNs and other S-NSSAIs do not need to select the same control plane function element and the same user plane function element.

[0129] The difference between the second and third methods is as follows: In the second method, the third indication information indicates that the PDU session initiated by the terminal, carrying the first DNN and the first S-NSSAI, needs to select the same control plane function network element and user plane function network element. In the third method, the fourth indication information indicates that the PDU session carrying the first DNN and the first S-NSSAI needs to select the same control plane function network element and the same user plane function element. That is, the third indication information is based on the granularity of the PDU sessions initiated by the terminal having the same DNN and the same S-NSSAI. The fourth indication information is based on the granularity of the PDU sessions having the same DNN and the same S-NSSAI, without limiting whether the PDU sessions are initiated by the same terminal. In this case, the PDU sessions carrying the first DNN and the same DNN and the same S-NSSAI can include PDU sessions corresponding to the first DNN established by one or more terminals. The sources of indication information differ depending on the granularity. When the granularity is based on the PDU sessions initiated by the terminal having the same DNN and the same S-NSSAI, the third indication information comes from the UDM or PCF. When the granularity is based on the PDU sessions having the same DNN and the same S-NSSAI, the fourth indication information comes from the PCF or the control plane function element.

[0130] It should be understood that the second, third, and fourth indications indicate that the PDU session corresponding to the first DNN (or the PDU session carrying the first DNN and the first S-NSSAI) needs to select the same control plane function network element and the same user plane function network element. In S220, the control plane function network element can determine, based on at least one of the second, third, and fourth indications, whether the PDU session corresponding to the first DNN (or the PDU session carrying the first DNN and the first S-NSSAI) needs to select the same control plane function network element and the same user plane function network element. That is, the foregoing only describes the affirmative case. In practical applications, the second, third, and fourth indications indicate whether the PDU session corresponding to the first DNN (or the PDU session carrying the first DNN and the first S-NSSAI) needs to select the same control plane function network element and the same user plane function network element. When the PDU session corresponding to the first DNN (or the PDU session carrying the first DNN and the first S-NSSAI) indicated by the second, third, and fourth indication information does not need to select the same control plane function network element and the same user plane function network element, the control plane function network element can determine, based on at least one of the second, third, and fourth indication information, that the PDU session corresponding to the first DNN does not need to (or the PDU session carrying the first DNN and the first S-NSSAI) select the same control plane function network element and the same user plane function network element, and the control plane function network element will not execute the subsequent steps in the embodiments of this application.

[0131] Following S220, the control plane function element identifies itself as the control plane function element for the PDU session corresponding to the first DNN (or the PDU session carrying the first DNN and the first S-NSSAI). The control plane function element allocates user plane function elements to the first PDU session and stores the correspondence between the first DNN (or the first DNN and the first S-NSSAI) and the allocated user plane function elements. For example, the control plane function element can allocate user plane function elements to the first PDU session based on the location of user plane function elements in the current network topology or the load of user plane function elements. The user plane function elements allocated to this first PDU session are also the user plane function elements allocated to the PDU session corresponding to the first DNN (or the PDU session carrying the first DNN and the first S-NSSAI).

[0132] It should be understood that the correspondence between the first DNN (or the first DNN and the first S-NSSAI) and the allocated user plane function network elements can be stored in the context of the terminal, or it can be stored separately. This application embodiment does not impose any restrictions on the way the correspondence is stored.

[0133] As an optional embodiment, the control plane function network element receives a second PDU session establishment request sent by the mobility management device, the second PDU session establishment request including the first DNN; the control plane function network element determines the user plane function network element of the first PDU session as the user plane function network element of the second PDU session. Specifically, when the control plane function network element receives a second PDU session establishment request, and the DNN carried in the second PDU session establishment request is the same as the first DNN, the control plane function network element can use the user plane function network element allocated for the first PDU session as the user plane function network element of the second PDU session.

[0134] As an optional embodiment, if the establishment request of the second PDU session includes a first DNN and a first S-NSSAI, and the control plane function element stores the correspondence between the first DNN and the first S-NSSAI and the allocated user plane function element, then the control plane function element determines the user plane function element of the first PDU session as the user plane function element of the second PDU session.

[0135] As an optional embodiment, the establishment request for the second PDU session includes a fifth indication information, which is used to indicate that the PDU session corresponding to the first DNN (or the PDU session carrying the first DNN and the first S-NSSAI) needs to select the same user plane function network element;

[0136] The process of the control plane function network element determining the user plane function network element of the first PDU session as the user plane function network element of the second PDU session includes: the control plane function network element determining the user plane function network element of the first PDU session in the context of the terminal according to the fifth indication information; and the control plane function network element determining the user plane function network element of the first PDU session as the user plane function network element of the second PDU session.

[0137] As an optional embodiment, the control plane function element determines the user plane function element of the first PDU session as the user plane function element of the second PDU session, including: the control plane function element determines the user plane function element of the first PDU session according to the first DNN and the correspondence (the first DNN corresponds to the user plane function element of the first PDU session); or includes: the control plane function element determines the user plane function element of the first PDU session according to the first DNN, the first S-NSSAI and the correspondence (the first DNN, the first S-NSSAI correspond to the user plane function element of the first PDU session); the control plane function element determines the user plane function element of the first PDU session as the user plane function element of the second PDU session according to the fifth indication information.

[0138] S230, the control plane function network element sends a first indication information to the mobility management device. The first indication information is used to indicate that the PDU session corresponding to the first DNN (or the PDU session carrying the first DNN and the first S-NSSAI) needs to select the same control plane function network element.

[0139] S240, the mobility management device receives first indication information from the control plane function network element, and the mobility management device saves the correspondence between the first DNN and the control plane function network element according to the first indication information, or saves the correspondence between the first DNN, the first S-NSSAI and the control plane function network element.

[0140] The mobility management device can receive first indication information from N control plane functional network elements. Based on this information, the mobility management device can store the correspondence between N DNNs and N control plane functional network elements, forming a first correspondence set. Alternatively, it can store a one-to-one correspondence between N DNNs, N S-NSSAIs, and N control plane functional network elements, forming a first correspondence set where N is a positive integer.

[0141] S250, the mobility management device determines the first control plane function network element as the control plane function network element of the second PDU session according to the first correspondence set. The first correspondence set is used to indicate that when the mobility management device receives establishment requests for multiple PDU sessions carrying a specific DNN, it needs to select the same specific control plane function network element. The first correspondence set includes the correspondence between the first DNN and the first control plane function network element. That is, the first correspondence set includes one or more elements, each element being a DNN corresponding to a control plane function network element. When the mobility management device receives an establishment request for any PDU session carrying a certain DNN, it needs to select the control plane function network element corresponding to that DNN. Alternatively, the first correspondence set can be used to indicate that multiple PDU sessions carrying a specific DNN and a specific S-NSSAI need to select the same specific control plane function network element. The mobility management device searches in the first correspondence set. When it finds a correspondence related to the first DNN and the first S-NSSAI carried by the second PDU session, it determines that the second PDU session needs to select the control plane function network element specified in the correspondence. In this way, PDU sessions with the same DNN and the same S-NSSAI can select the same control plane function network element.

[0142] S260, the mobility management device sends a request to establish the second PDU session to the first control plane function network element.

[0143] Optionally, the establishment request for the second PDU session carries the first DNN. Alternatively, the establishment request for the second PDU session carries both the first DNN and the first S-NSSAI.

[0144] Therefore, in this embodiment, the control plane function element can determine that the PDU sessions corresponding to the same DNN (PDU sessions carrying the same DNN and the same S-NSSAI) need to select the same control plane function element and the same user plane function element. In this way, when switching from a 5G network to a 4G network, the same control plane function element and the same user plane function element can still be selected, thereby enabling control of the AMBR.

[0145] The preceding text describes how the control plane function network element needs to select the same control plane function network element and the same user plane function network element to determine the PDU session corresponding to the first DNN (or the PDU session carrying the first DNN and the first S-NSSAI). The following describes how the mobility management device needs to select the same control plane function network element, or the same user plane function network element and the same user plane function network element, to determine the PDU session corresponding to the first DNN (or the PDU session carrying the first DNN and the first S-NSSAI). The method for determining the mobility management network element is similar to that for determining the control plane function network element, and is briefly described below. Similarly, in method 300, the PDU session corresponding to the first DNN can be replaced with the PDU session carrying the first DNN and the first S-NSSAI; method 300 only uses the PDU session corresponding to the first DNN as an example for illustration.

[0146] Figure 3 This application illustrates a method 300 for determining a PDU session service network element, which includes:

[0147] S310, the mobility management device receives a first PDU session establishment request sent by the terminal, the first PDU session establishment request including a first data network name (DNN).

[0148] Optionally, the request to establish the first PDU session may further include at least one of the following: the SSC mode of the first PDU session, the session identifier of the first PDU session, the S-NSSAI corresponding to the first PDU session, and the terminal identifier of the terminal initiating the first PDU session.

[0149] S320, the mobility management device determines that the PDU session corresponding to the first DNN needs to select the same control plane function network element.

[0150] Alternatively, S320 may also be: the mobility management device determines that the PDU session corresponding to the first DNN needs to select the same control plane function network element and the same user plane function network element.

[0151] In S320, the same control plane function network element can be selected for the PDU session corresponding to the first DNN through one or more of the following three methods.

[0152] In the first method, the establishment request of the first PDU session further includes second indication information, which is used to indicate that the PDU session corresponding to the first DNN established by the terminal needs to select the same control plane function network element; S320, including: the mobility management device determines, according to the second indication information, that the PDU session corresponding to the first DNN established by the terminal needs to select the same control plane function network element.

[0153] In the first approach, there are two possible scenarios: First, the mobility management device (MMD) determines that the PDU session corresponding to the first DNN established by the terminal needs to select the same control plane function network element (CFA). For example, when the SSC mode of the first PDU session is mode 1, the MMD can determine that the PDU session corresponding to the first DNN established by the terminal needs to select the same CFA. Then, the MMD sends a second indication message to the CFA to indicate that the PDU session corresponding to the first DNN established by the terminal needs to select both the same CFA and the same user plane function network element. Second, the MMD directly sends the second indication message to the CFA. In this case, the second indication message indicates that the session and service continuity SSC of the first PDU session is in SSC mode 1. That is, the MMD forwards the SSC mode 1 in the establishment request of the first PDU session to the CFA. After receiving the establishment request of the first PDU session, the control plane function network element determines, based on the SSC mode 1 carried in the establishment request of the first PDU session, that the PDU session corresponding to the first DNN established by the terminal needs to select the same control plane function network element and the same user plane function network element.

[0154] The second method, S320, includes: the mobility management device determining, based on third indication information, that the PDU session corresponding to the first DNN established by the terminal needs to select the same control plane function network element; the third indication information is used to indicate that the PDU session corresponding to the first DNN established by the terminal needs to select the same control plane function network element, wherein the third indication information comes from the user data management network element or from the policy management network element.

[0155] In other words, the third indication information used to instruct the PDU session corresponding to the first DNN established by the terminal to select the same control plane function element can come from the UDM or the PCF. For example, the third indication information can come from the subscription data of the UDM, such as the third indication information in the subscription data of the UDM indicating that the PDU session initiated by the terminal carrying the first DNN needs to select the same control plane function element. Alternatively, the third indication information can come from the policy rules of the first DNN of the PCF.

[0156] The third method, S320, includes: the mobility management device determining, based on the fourth indication information, that the PDU session corresponding to the first DNN needs to select the same control plane function network element; the fourth indication information is used to indicate that the PDU session corresponding to the first DNN needs to select the same control plane function network element; wherein the fourth indication information comes from the policy management network element or from the mobility management network element.

[0157] In other words, the fourth indication information used to indicate that the PDU session corresponding to the first DNN needs to select the same control plane function network element can come from the PCF or from the mobility management device itself, that is, the mobility management device has locally configured the relevant rules of the DNN. For example, some specific DNNs require the PDU sessions to select the same control plane function network element; other specific DNNs do not require the PDU sessions to select the same control plane function network element.

[0158] The difference between the second and third methods is that in the second method, the third indication information indicates that the PDU session corresponding to the first DNN established by the terminal needs to select the same control plane function network element, while in the third method, the fourth indication information indicates that the PDU session corresponding to the first DNN needs to select the same control plane function network element. That is, the third indication information is at the terminal level, while the fourth indication information is at the first DNN level. The PDU session corresponding to the first DNN can include one or more PDU sessions established by terminals corresponding to the first DNN. The source of the indication information differs depending on the granularity. When the granularity is at the terminal level, the third indication information comes from the UDM or PCF; when the granularity is at the DNN level, the fourth indication information comes from the PCF or mobility management network element.

[0159] The mobility management device determines that the PDU session corresponding to the first DNN needs to select the same control plane function network element and the same user plane function network element. It may also determine that the PDU session corresponding to the first DNN needs to select the same control plane function network element and the same user plane function network element through one or more of the following three methods.

[0160] In the first method, the establishment request for the first PDU session includes second indication information. This second indication information indicates that the PDU session corresponding to the first DNN established by the terminal needs to select the same control plane function network element and the same user plane function network element. The mobility management device determines that the PDU session corresponding to the first DNN needs to select the same control plane function network element and the same user plane function network element by: the mobility management device determining, based on the second indication information, that the PDU session corresponding to the first DNN established by the terminal needs to select the same control plane function network element and the same user plane function network element.

[0161] In one possible implementation, the second indication information is Session and Service Continuity (SSC) Mode 1.

[0162] In the second method, the mobility management device determines that the PDU session corresponding to the first DNN needs to select the same control plane function network element and the same user plane function network element, including: the mobility management device determines, based on third indication information, that the PDU session established by the terminal corresponding to the first DNN needs to select the same control plane function network element and the same user plane function network element; the third indication information is used to indicate that the PDU session established by the terminal corresponding to the first DNN needs to select the same control plane function network element and the same user plane function network element, wherein the third indication information comes from the user data management network element or from the policy management network element.

[0163] In the third method, the mobility management device determines that the PDU session corresponding to the first DNN needs to select the same control plane function network element and the same user plane function network element, including: the mobility management device determines that the PDU session corresponding to the first DNN needs to select the same control plane function network element and the same user plane function network element according to the fourth indication information; the fourth indication information is used to indicate that the PDU session corresponding to the first DNN needs to select the same control plane function network element and the same user plane function network element, wherein the fourth indication information comes from the policy management network element or from the mobility management network element.

[0164] As an optional embodiment, S320 may include: when the mobility management device determines, based on a first correspondence set, that the first control plane function element is the control plane function element of the second PDU session, the mobility management device determines that the PDU session corresponding to the first DNN needs to select the same control plane function element, or needs to select the same control plane function element and the same user plane function element; wherein, the first correspondence set is used to indicate that when the mobility management device receives establishment requests for multiple PDU sessions carrying a specific DNN, the same specific control plane function element needs to be selected; wherein, the first correspondence set includes the correspondence between the first DNN and the first control plane function element.

[0165] In this embodiment of the application, in addition to determining, based on one or more of the three methods, that the PDU session corresponding to the first DNN needs to select the same control plane function network element, or the same control plane function network element and the same user plane function network element, the mobility management device can also determine that when the first control plane function network element is determined to be the control plane function network element of the second PDU session from the first correspondence set in S250, the mobility management device can determine that the PDU session corresponding to the first DNN needs to select the same control plane function network element, or the same control plane function network element and the same user plane function network element. That is, as long as a specific control plane function network element corresponding to the established first DNN is found in the first correspondence set, the mobility management device can determine that the PDU session corresponding to the first DNN needs to select that specific control plane function network element, or the same control plane function network element and the same user plane function network element.

[0166] As an optional embodiment, if the mobility management device determines that the PDU session corresponding to the first DNN needs to select the same control plane function network element and the same user plane function network element, the method further includes: the mobility management device sending fifth indication information to the first control plane function network element, the fifth indication information being used to indicate that the PDU session corresponding to the first DNN corresponds to the same user plane function network element. For example, the establishment request of the first PDU session can carry the fifth indication information.

[0167] S330, the mobility management device determines the first control plane function element as the control plane function element of the first PDU session.

[0168] S340, the mobility management device sends a first PDU session establishment request to the first control plane function network element, and the first control plane function network element receives the first PDU session establishment request sent by the mobility management device. The first PDU session establishment request includes a first data network name (DNN).

[0169] S350, the control plane function element determines that the PDU session corresponding to the first DNN needs to select the same user plane function element.

[0170] In S350, the requirement for the same user plane function network element to be selected for the PDU session corresponding to the first DNN can be determined in the following three ways:

[0171] In the first method, the establishment request of the first PDU session includes second indication information, which is used to indicate that the PDU session corresponding to the first DNN established by the terminal needs to select the same user plane function network element.

[0172] Wherein, the control plane function network element determines that the PDU session corresponding to the first DNN needs to select the same user plane function network element, including:

[0173] The control plane function element determines, based on the second indication information, that the PDU session corresponding to the first DNN needs to select the same user plane function element.

[0174] Optionally, the second indication information is Session and Service Continuity (SSC) Mode 1.

[0175] The second method, S350, includes: the control plane function network element determines, according to the third indication information, that the PDU session corresponding to the first DNN established by the terminal needs to select the same user plane function network element, wherein the third indication information is used to indicate that the PDU session corresponding to the first DNN established by the terminal needs to select the same user plane function network element; wherein the third indication information comes from the user data management network element or from the policy management network element.

[0176] The third method, S350, includes: the control plane function network element determines, according to the fourth indication information, that the PDU session corresponding to the first DNN needs to select the same user plane function network element, wherein the fourth indication information is used to indicate that the PDU session corresponding to the first DNN needs to select the same user plane function network element; wherein the fourth indication information comes from the policy management network element or from the control plane function network element.

[0177] It should be understood that the three ways in which the control plane function network element needs to select the same user plane function network element to determine the PDU session corresponding to the first DNN are the same as the three ways in which the control plane function network element needs to select the same control plane function network element and the same user plane function network element to determine the PDU session corresponding to the first DNN in S220. To avoid redundancy, this application embodiment will not describe this in detail.

[0178] As an optional embodiment, S350 includes: the control plane function network element determining, based on the fifth indication information, that the PDU session corresponding to the first DNN needs to select the same user plane function network element. In this case, the control plane function network element may not determine, based on the above three methods, that the PDU session corresponding to the first DNN needs to select the same user plane function network element, but instead directly determine it based on the fifth indication information sent by the mobility management network element. This helps to save signaling overhead on the control plane function network element.

[0179] S360, the control plane function element determines the first user plane function element as the user plane function element of the first PDU session.

[0180] As an optional embodiment, the control plane function network element determines whether a PDU session with the same first DNN has already been established. If a PDU session with the same first DNN has already been established, the first user plane function network element is the same user plane function network element as the established PDU session with the same first DNN. In this embodiment, the first PDU session can be the first PDU session established by the terminal carrying the first DNN, or it can be a non-first PDU session established by the terminal carrying the first DNN. If the first PDU is the first PDU session, the control plane function network element can determine the first user plane function network element based on the location of user plane function network elements in the current network topology or the load of user plane function network elements. If the first PDU session is a non-first PDU session, the control plane function network element determines the user plane function network element of the already established PDU session with the first DNN as the first user plane function network element.

[0181] It should be understood that the three methods by which the mobility management device selects the same control plane function network element and the same user plane function network element to determine the PDU session corresponding to the first DNN are similar to the three methods by which the control plane control network element selects the same control plane function network element and the same user plane function network element to determine the PDU session corresponding to the first DNN. To avoid redundancy, this embodiment will not describe this in detail.

[0182] It should be understood that, in the embodiments of this application, for example, the first control plane function network element can be any control plane function network element and does not represent the same device. That is, in the embodiments of this application, "first" and "second" do not specifically refer to any one, but rather refer to any one of them. For another example, in the embodiments of this application, the same term may have different meanings in different method embodiments. In method 200, the second indication information is used to indicate that the PDU session corresponding to the first DNN established by the terminal needs to select the same control plane function network element and the same user plane function network element; in method 300, the second indication information is used to indicate that the PDU session corresponding to the first DNN established by the terminal needs to select the same control plane function network element. The embodiments of this application do not impose any limitations on this.

[0183] The following is combined with Figures 4 to 6 This application describes a method for determining the PDU session service network element according to embodiments of the present application. Methods 400-600 are illustrated using the Mobility Management Function (AMF) device and the Control Plane Function (SMF+PGW-C) network element as examples, but the embodiments of the present application are not limited thereto.

[0184] Currently, there are no restrictions on choosing SMF+PGW-C or UPF for multiple PDU sessions within the same DNN. For example, different SMF+PGW-Cs may serve multiple PDU sessions within the same DNN. Furthermore, even if these PDU sessions share the same SMF+PGW-C, their UPF+PGW-Cs may differ. In this situation, if the APN equals the DNN, and all PDU sessions within the same DNN need to switch to the 4G network, a problem arises. Since it's impossible to guarantee that PDN connections with the same APN will select the same PGW-C on the 4G network, APN AMBR cannot be implemented.

[0185] To address the above issues, it is assumed that PDU sessions for DNNs requiring a switch to the 4G network are configured or restricted to the same network slice. If a terminal requests a PDU session from the same DNN, but the PDU session is in a different S-NSSAI, the network device can reject the terminal's request.

[0186] In the embodiments of this application, the following two scenarios are described: First, SMF+PGW-C determines to select the same SMF+PGW-C and UPF+PGW-U. Second, AMF determines to select the same SMF+PGW-C, or selects the same SMF+PGW-C and UPF+PGW-U.

[0187] In the first scenario, when the terminal first requests a PDU session for the DNN, the SMF detects that all PDU sessions for that DNN need to switch to the 4G network, or that they need to select the same SMF+PGW-C and the same UPF+PGW-U (e.g., based on the SMF's local configuration, an indication in the DNN's subscription data, or an indication received by the SMF from the PCF). The SMF+PGW-C stores the mapping between the DNN and UPF+PGW-U, and then instructs the AMF to select the same SMF+PGW-C the next time it receives a PDU session establishment request for the same DNN. The AMF stores the mapping between the DNN and the SMF. When the AMF receives a new PDU session establishment request for the same DNN, it selects the same SMF+PGW-C. The SMF+PGW-C uses the UPF+PGW-U of the previously established PDU session corresponding to that DNN as the UPF+PGW-U of the new PDU session. In this scenario, because all PDU sessions within the same DNN select the same SMF+PGW-C and the same UPF+PGW-U, all PDU sessions within the same DNN can switch to the 4G network without conflict.

[0188] Optionally, in the first scenario, when the terminal first requests to establish a PDU session carrying a specific DNN and S-NSSAI, the SMF detects that all PDU sessions related to that DNN and S-NSSAI need to switch to the 4G network or need to select the same SMF+PGW-C and the same UPF+PGW-U (e.g., based on the SMF's local configuration, indications in the DNN's subscription data, or indications received by the SMF from the PCF). The SMF+PGW-C stores the mapping between the DNN and UPF+PGW-U, and then instructs the AMF to select the same SMF+PGW-C the next time it receives a request to establish a PDU session with the same DNN and S-NSSAI. The AMF stores the mapping between the DNN, S-NSSAI, and SMF. When the AMF receives a request to establish a new PDU session carrying the same DNN and the same S-NSSAI, it selects the same SMF+PGW-C. SMF+PGW-C uses the UPF+PGW-U of the previously established PDU session corresponding to the DNN and S-NSSAI as the UPF+PGW-U of the new PDU session. In this case, because all PDU sessions of the same DNN and S-NSSAI select the same SMF+PGW-C and the same UPF+PGW-U, all PDU sessions of the same DNN and S-NSSAI can switch to the 4G network without conflict.

[0189] In the second scenario, when a terminal first requests a PDU session for a DNN, the AMF detects that all PDU sessions for that DNN need to switch to the 4G network. The AMF determines to select the same SMF+PGW-C for all PDU sessions of that DNN (e.g., based on the AMF's local configuration, an indication in the DNN's subscription data, or an indication received by the AMF from the PCF). The AMF stores the mapping between the DNN and SMF+PGW-C. Optionally, the AMF determines to select the same SMF+PGW-C and the same UPF+PGW-U for all PDU sessions of that DNN. The AMF instructs the SMF+PGW-C to select the same UPF+PGW-U for the DNN's PDU sessions. Optionally, the SMF+PGW-C itself determines to select the same UPF+PGW-U for the DNN's PDU sessions. When the AMF receives a new PDU session establishment request for that DNN (for the same terminal), the AMF selects SMF+PGW-C according to the mapping. SMF+PGW-C uses the UPF+PGW-U of the previously established PDU session corresponding to the DNN as the UPF+PGW-U of the new PDU session. In this case, because all PDU sessions on the same DNN select the same SMF+PGW-C and the same UPF+PGW-U, all PDU sessions on the same DNN can switch to the 4G network without conflict.

[0190] Optionally, in the second scenario, when the terminal first requests to establish a PDU session carrying a certain DNN and a certain S-NSSAI, the AMF detects that all PDU sessions of that DNN need to switch to the 4G network. The AMF determines to select the same SMF+PGW-C for all PDU sessions of that DNN and S-NSSAI (e.g., based on the AMF's local configuration, an indication in the DNN's subscription data, or an indication received by the AMF from the PCF). The AMF stores the correspondence between the DNN and S-NSSAI and the SMF+PGW-C. Optionally, the AMF determines to select the same SMF+PGW-C and the same UPF+PGW-U for all PDU sessions of that DNN and S-NSSAI. The AMF instructs the SMF+PGW-C to select the same UPF+PGW-U for the PDU sessions of that DNN and S-NSSAI. Optionally, the SMF+PGW-C itself determines that the PDU sessions of that DNN and S-NSSAI select the same UPF+PGW-U. When the AMF receives a new PDU session establishment request for the same DNN and S-NSSAI (for the same terminal), the AMF selects the SMF+PGW-C based on the correspondence. The SMF+PGW-C uses the UPF+PGW-U of the previously established PDU session corresponding to the DNN and S-NSSAI as the UPF+PGW-U of the new PDU session. In this case, because all PDU sessions for the same DNN and the same S-NSSAI select the same SMF+PGW-C and the same UPF+PGW-U, all PDU sessions for the same DNN and the same S-NSSAI can switch to the 4G network without conflict.

[0191] The following describes method 400 for determining the PDU session service network element in the first scenario, such as... Figure 4 As shown, method 400 includes:

[0192] S401, the terminal sends an establishment request to the AMF to request the establishment of a first PDU session. The establishment request for the first PDU session carries the identifier of the first PDU session and the first DNN.

[0193] Optionally, the request to establish the first PDU session may also carry at least one of the following information: terminal identifier, first S-NSSAI, and SSC mode.

[0194] S402, the AMF receives the first PDU session establishment request sent by the terminal, determines that the terminal is establishing access to the PDU session indicated by the first DNN for the first time, and then the AMF is the SMF+PGW-C determined by the first PDU session.

[0195] Specifically, after receiving a request from the terminal to establish a PDU session carrying the first DNN, the AMF checks in the terminal's relevant information stored in the AMF whether the terminal has established a PDU session with the first DNN. If not, the first PDU session is the first time the terminal has established a PDU session with the first DNN, and the AMF records the information of the first DNN in the terminal's relevant information so that when the first PDU session is received again, it can be determined that the next received PDU session with the first DNN is not the first session.

[0196] If it is determined that the terminal is establishing a PDU session with the first DNN indication for the first time, the AMF can determine the anchored SMF+PGW-C for the first PDU session according to existing technology. For example, the AMF determines the SMF+PGW-C based on the first S-NSSAI, DNN, terminal subscription information, and local operator policy in the establishment request of the first PDU session.

[0197] S403, AMF sends a request to establish a first PDU session to SMF+PGW-C determined in S402. The request to establish a first PDU session carries the identifier of the first PDU session and the first DNN.

[0198] S404, SMF+PGW-C receives the establishment request for the first PDU session sent by AMF, and determines whether the PDU session corresponding to the first DNN in the establishment request for the first PDU session needs to select the same SMF+PGW-C and the same UPF+PGW-U.

[0199] Specifically, in S404, it is determined whether the PDU session corresponding to the first DNN in the establishment request of the first PDU session needs to select the same SMF+PGW-C and the same UPF+PGW-U through one or more of the following five methods.

[0200] In the first method, SMF+PGW-C obtains the subscription data of the first DNN. The subscription data of the first DNN includes second indication information, which indicates whether all PDU sessions corresponding to the first DNN need to select the same SMF+PGW-C and the same UPF+PGW-U. Alternatively, the second indication information indicates whether all PDU sessions corresponding to the first DNN and S-NSSAI need to select the same SMF+PGW-C and the same UPF+PGW-U.

[0201] Specifically, the subscription data of the first DNN established by the terminal can be stored in the UDM, and the SMF+PGW-C can obtain the subscription data of the first DNN established by the terminal from the UDM. The subscription data of the first DNN established by multiple terminals can be stored in the UDM, SMF+PGW-C, or AMF, and the SMF+PGW-C can obtain the subscription data of the first DNN established by multiple terminals from the UDM, AMF, or locally.

[0202] In one possible implementation, when the SMF+PGW-C receives a request from the AMF to establish a first PDU session, the SMF+PGW-C requests the terminal's subscription data from the UDM. This subscription data includes the subscription data of the first DNN. Based on the subscription data of the first DNN, the SMF+PGW-C determines whether the currently received first PDU session carrying the first DNN should use the same SMF+PGW-C and the same UPF+PGW-U as other PDU sessions initiated by the terminal carrying the same first DNN. These other PDU sessions carrying the same first DNN can specifically be PDU sessions initiated by the terminal before the current PDU session, or PDU sessions that may be initiated subsequently.

[0203] The second approach involves SMF+PGW-C determining, based on preset rules, whether all PDU sessions corresponding to the first DNN need to select the same SMF+PGW-C and the same UPF+PGW-U. For example, the preset rules could be that one or more PDU sessions corresponding to certain specific DNNs need to select the same SMF+PGW-C and the same UPF+PGW-U, while one or more PDU sessions corresponding to certain specific DNNs do not need to select the same SMF+PGW-C and the same UPF+PGW-U. Alternatively, the preset rules could be that one or more PDU sessions corresponding to certain specific DNNs and specific S-NSSAIs need to select the same SMF+PGW-C and the same UPF+PGW-U, while one or more PDU sessions corresponding to certain specific DNNs and specific S-NSSAIs do not need to select the same SMF+PGW-C and the same UPF+PGW-U.

[0204] Specifically, when the SMF+PGW-C receives a request to establish the first PDU session from the AMF, the SMF+PGW-C finds the preset rules corresponding to the first DNN and determines whether the currently received first PDU session carrying the same first DNN needs to select the same SMF+PGW-C and the same UPF+PGW-U as other PDU sessions carrying the same first DNN. Alternatively, the SMF+PGW-C finds the preset rules corresponding to the first DNN and the first S-NSSAI (carried in the request to establish the first PDU session) and determines whether the currently received first PDU session carrying the same first DNN and the first S-NSSAI needs to select the same SMF+PGW-C and the same UPF+PGW-U as other PDU sessions carrying the same first DNN and the first S-NSSAI. Other PDU sessions carrying the same first DNN or the same first S-NSSAI can be PDU sessions initiated by different terminals before the current PDU session, or PDU sessions that may be initiated by different terminals subsequently. The PDU session corresponding to the first DNN can be a PDU session carrying the first DNN established by any different terminals, or the PDU session corresponding to the first DNN can be a PDU session carrying the first DNN established by a single terminal. This application embodiment does not impose any restrictions on this. Similarly, the PDU session carrying the first DNN and the first S-NSSAI can be a PDU session established by any different terminals, or the PDU session carrying the first DNN and the first S-NSSAI can be a PDU session established by a single terminal. This application embodiment does not impose any restrictions on this.

[0205] The third method involves the SMF+PGW-C determining, based on the SSC mode of the first PDU session, whether the PDU sessions established by the terminal carrying the first DNN need to select the same SMF+PGW-C and the same UPF+PGW-U. For example, if the SSC mode of the first PDU session is SSC mode 1, then the SMF+PGW-C determines that the PDU sessions established by the terminal carrying the first DNN (it can be assumed that the SSC modes of the PDU sessions established by the terminal carrying the first DNN are all the same) need to select the same SMF+PGW-C and the same UPF+PGW-U; if the SSC mode of the first PDU session is SSC mode 2 or SSC mode 3, then the SMF+PGW-C determines that the PDU session does not need to select the same SMF+PGW-C and the same UPF+PGW-U.

[0206] The fourth method involves the SMF+PGW-C obtaining third indication information from the PCF. This third indication information indicates whether all PDU sessions corresponding to the first DNN need to select the same SMF+PGW-C and the same UPF+PGW-U. In this method, all PDU sessions corresponding to the first DNN can be all PDU sessions carrying the first DNN established by a single terminal, or all PDU sessions carrying the first DNN established by different terminals. Alternatively, the SMF+PGW-C obtains third indication information from the PCF. This third indication information indicates whether all PDU sessions carrying the first DNN and the first S-NSSAI need to select the same SMF+PGW-C and the same UPF+PGW-U. In this method, the PDU sessions carrying the first DNN and the first S-NSSAI can be PDU sessions established by a single terminal, or PDU sessions established by different terminals.

[0207] When the SMF+PGW-C receives a request to establish a first PDU session from the AMF, the SMF+PGW-C sends a request message to the PCF to request the third indication information. Based on the third indication information, the SMF+PGW-C determines whether the currently received first PDU session carrying the first DNN needs to use the same SMF+PGW-C and the same UPF+PGW-U as other PDU sessions carrying the same first DNN. Alternatively, based on the third indication information, the SMF+PGW-C determines whether the currently received first PDU session carrying the first DNN and the first S-NSSAI needs to use the same SMF+PGW-C and the same UPF+PGW-U as other PDU sessions carrying the same first DNN and the first S-NSSAI. These other PDU sessions carrying the same first DNN can specifically be PDU sessions initiated by different terminals before the current PDU session, or PDU sessions that may be initiated by different terminals subsequently.

[0208] In the fifth method, the terminal carries fourth indication information in the establishment request of the first PDU session in S401. This fourth indication information indicates that all PDU sessions established by the terminal carrying the first DNN need to select the same SMF+PGW-C and the same UPF+PGW-U. Alternatively, this fourth indication information indicates that all PDU sessions established by the terminal carrying the first DNN and the first S-NSSAI need to select the same SMF+PGW-C and the same UPF+PGW-U. In S403, this fourth indication information is sent to the SMF+PGW-C through the establishment request of the first PDU session. The SMF+PGW-C determines, based on the fourth indication information in the establishment request of the first PDU session, that the PDU sessions established by the terminal carrying the first DNN (or PDU sessions carrying the first DNN and the first S-NSSAI) need to select the same SMF+PGW-C and the same UPF+PGW-U. For example, this fourth indication information can be SSC mode 1.

[0209] S405, if it is determined in S404 that the PDU session carrying the first DNN needs to select the same SMF+PGW-C and the same UPF+PGW-U, then SMF+PGW-C itself is the same SMF+PGW-C, and SMF+PGW-C selects the same UPF+PGW-U for the PDU session carrying the first DNN. Alternatively, if it is determined in S404 that the PDU sessions carrying the first DNN and the first S-NSSAI need to select the same SMF+PGW-C and the same UPF+PGW-U, then SMF+PGW-C itself is the same SMF+PGW-C, and SMF+PGW-C selects the same UPF+PGW-U for the PDU sessions carrying the first DNN and the first S-NSSAI.

[0210] Specifically, after receiving a request from the AMF to establish a PDU session carrying the first DNN, the SMF+PGW-C checks in the relevant information stored in the SMF+PGW-C whether a PDU session for the first DNN has been established. If not, the first PDU session is the first PDU session established with the first DNN, and the SMF+PGW-C records the information of the first DNN in the relevant information so that when the first PDU session is received again, it can be determined that the next PDU session received with the first DNN is not the first session.

[0211] If it is determined that the first PDU session is the first PDU session established carrying the first DNN, SMF+PGW-C can determine the anchored UPF+PGW-U for the first PDU session according to existing technology. For example, SMF+PGW-C can select the UPF+PGW-U for the first PDU session based on the location information, load information, etc. of the UPF+PGW-U.

[0212] Optionally, SMF+PGW-C saves the correspondence between the first DNN and the selected UPF+PGW-U. For example, as shown in Table 1, the first column represents the DNN and the second column represents the UPF+PGW-U identifier. That is, the PDU session corresponding to DNN1 needs to select SMF+PGW-C and UPF+PGW-U 1, and the PDU session corresponding to DNN2 needs to select SMF+PGW-C and UPF+PGW-U 2.

[0213] Table 1

[0214] DNN UPF+PGW-U logo DNN1 UPF+PGW-U 1 DNN2 UPF+PGW-U 2

[0215] Optionally, SMF+PGW-C saves the correspondence between DNN, S-NSSAI, and the selected UPF+PGW-U. For example, as shown in Table 2, the first column represents DNN, the second column represents S-NSSAI, and the third column represents the UPF+PGW-U identifier. That is, the PDU sessions corresponding to DNN1 and S-NSSAI1 need to select SMF+PGW-C and UPF+PGW-U 1, and the PDU sessions corresponding to DNN2 and S-NSSA2 need to select SMF+PGW-C and UPF+PGW-U 2.

[0216] Table 2

[0217] DNN S-NSSAI UPF+PGW-U logo DNN1 S-NSSAI1 UPF+PGW-U 1 DNN2 S-NSSAI2 UPF+PGW-U 2

[0218] S406, SMF+PGW-C sends a fifth indication message to AMF, which instructs AMF to select the same SMF+PGW-C when it receives the PDU session corresponding to the first DNN again. Alternatively, the fifth indication message instructs AMF to select the same SMF+PGW-C when it receives the PDU session corresponding to the first DNN and the first S-NSSAI again.

[0219] Optionally, SMF+PGW-C can send the fifth instruction message to AMF through the response message of the establishment request of the first PDU session, or SMF+PGW-C can send the fifth instruction message to AMF separately.

[0220] S407, the AMF receives the fifth indication information sent by the SMF+PGW-C. The AMF can receive the fifth indication information sent by multiple SMF+PGW-Cs and store the correspondence between multiple DNNs and multiple SMF+PGW-Cs. Alternatively, it can maintain the correspondence between multiple DNNs, multiple S-NSSAIs, and multiple SMF+PGW-Cs.

[0221] For example, as shown in Table 3, the first column represents the DNN, and the second column represents the SMF+PGW-C identifier. The AMF receives the fifth indication information sent by SMF+PGW-C 1 and SMF+PGW-C 2. The fifth indication information sent by SMF+PGW-C 1 is used to indicate that when the AMF receives the PDU session corresponding to DNN1 again, it should select SMF+PGW-C 1. The fifth indication information sent by SMF+PGW-C 2 is used to indicate that when the AMF receives the PDU session corresponding to DNN2 again, it should select SMF+PGW-C 2. That is, the PDU session corresponding to DNN1 needs to select SMF+PGW-C1, and the PDU session corresponding to DNN2 needs to select SMF+PGW-C 2.

[0222] Table 3

[0223] DNN SMF+PGW-C mark DNN1 SMF+PGW-C 1 DNN2 SMF+PGW-C 2

[0224] Alternatively, as shown in Table 4, the first column represents DNN, the second column represents S-NSSAI, and the third column represents the SMF+PGW-C identifier. The AMF receives the fifth indication information sent by SMF+PGW-C 1 and SMF+PGW-C 2. The fifth indication information sent by SMF+PGW-C 1 is used to instruct the AMF to select SMF+PGW-C 1 when it receives the PDU session corresponding to DNN1 and S-NSSAI1 again, and the fifth indication information sent by SMF+PGW-C 2 is used to instruct the AMF to select SMF+PGW-C 2 when it receives the PDU session corresponding to DNN2 and S-NSSAI2 again. That is, the PDU session corresponding to DNN1 and S-NSSAI1 needs to select SMF+PGW-C1, and the PDU session corresponding to DNN2 and S-NSSAI2 needs to select SMF+PGW-C 2.

[0225] Table 4

[0226] DNN S-NSSAI SMF+PGW-C mark DNN1 S-NSSAI1 SMF+PGW-C 1 DNN2 S-NSSAI2 SMF+PGW-C 2

[0227] It should be understood that one SMF+PGW-C can correspond to one or more DNNs, but one DNN corresponds to one SMF+PGW-C. If S-NSSAI is considered, then one DNN and one S-NSSAI correspond to one SMF+PGW-C.

[0228] Optionally, the AMF can save the mapping between DNNs and SMF+PGW-C, either within the terminal context or separately. Alternatively, the AMF can save the mapping between DNNs and SMF+PGW-C, as well as the indication information regarding whether the PDU sessions corresponding to the DNNs need to be selected in the same SMF+PGW-C, either within the terminal context or separately. For example, as shown in Table 5, the PDU sessions corresponding to DNN 1 can be selected in SMF+PGW-C 1, the PDU sessions corresponding to DNN 2 can be selected in SMF+PGW-C 2, and the PDU sessions corresponding to DNN 3 do not all need to be selected in SMF+PGW-C 3. Of course, when saving, only the first three columns of Table 5 can be saved, omitting the fourth column. In this case, the saved PDU sessions corresponding to the DNNs need to be selected in the same SMF+PGW-C.

[0229] Table 5

[0230]

[0231]

[0232] Optionally, the AMF can save the correspondence between DNN, S-NSSAI, and SMF+PGW-C, either within the terminal context or separately. Alternatively, the AMF can save the correspondence between DNN, S-NSSAI, and SMF+PGW-C, as well as the indication information regarding whether the PDU session corresponding to the DNN needs to be selected within the same SMF+PGW-C, either within the terminal context or separately. For example, as shown in Table 6, the PDU session corresponding to DNN 1 and S-NSSAI1 can be selected within SMF+PGW-C 1, the PDU session corresponding to DNN2 and S-NSSA2 can be selected within SMF+PGW-C2, and the PDU sessions corresponding to DNN3 and S-NSSAI3 do not all need to be selected within SMF+PGW-C 3. Of course, when saving, only the first four columns of Table 6 can be saved, omitting the fifth column. In this case, the saved PDU sessions corresponding to the DNN need to be selected within the same SMF+PGW-C.

[0233] Table 6

[0234]

[0235] S408, the process of establishing the first PDU session by the terminal, RAN, AMF, SMF+PGW-C, UDM+HSS, PCF, and UPF+PGW-U refers to the prior art. To avoid redundancy, the embodiments of this application will not be described in detail here.

[0236] S409, the terminal initiates a second PDU session establishment request to the AMF again. This second PDU session establishment request includes the identifier of the second PDU session and the first DNN. Here, it is assumed that the second PDU session has the same first DNN as the first PDU session, and the first DNN is assumed to be DNN1.

[0237] Optionally, the establishment request for the second PDU session may also carry at least one of the following information: terminal identifier, S-NSSAI, and SSC mode.

[0238] S410, the AMF can determine the SMF+PGW-C corresponding to DNN1 as SMF+PGW-C 1 according to Table 3 (SMF+PGW-C 1 is the aforementioned SMF+PGW-C). Alternatively, the AMF can determine the SMF+PGW-C corresponding to DNN1 as SMF+PGW-C 1 according to Table 5, and all PDU sessions corresponding to DNN1 can be selected to SMF+PGW-C 1. Alternatively, the AMF can determine the SMF+PGW-C corresponding to DNN1 and S-NSSAI1 as SMF+PGW-C 1 according to Table 4 (SMF+PGW-C 1 is the aforementioned SMF+PGW-C). Alternatively, the AMF can determine the SMF+PGW-C corresponding to DNN1 and S-NSSAI1 as SMF+PGW-C 1 according to Table 5, and all PDU sessions corresponding to DNN1 and S-NSSAI1 can be selected to SMF+PGW-C 1.

[0239] It should be understood that if the AMF does not determine the SMF+PGW-C corresponding to the second PDU session in S410, the AMF will determine the SMF+PGW-C according to the existing technology based on the S-NSSAI, DNN, terminal subscription information and local operator policy of the second PDU session.

[0240] S411, AMF sends a request to establish a second PDU session to SMF+PGW-C 1. The request to establish a second PDU session carries the identifier of the second PDU session and the DNN.

[0241] Optionally, the establishment request for the second PDU session may also carry at least one of the terminal's identifier, S-NSSAI, and SSC mode.

[0242] S412, SMF+PGW-C 1 selects UPF+PGW-U for the second PDU session. Based on the DNN and selected UPF+PGW-U correspondence saved in Table 1, if the DNN for the second PDU session is DNN1, then SMF+PGW-C determines the UPF+PGW-U for the second PDU session as UPF+PGW-U 1. Alternatively, based on the DNN, S-NSSAI, and selected UPF+PGW-U correspondence saved in Table 2, if the DNN for the second PDU session is DNN1 and the S-NSSAI for the second PDU session is S-NSSAI1, then SMF+PGW-C determines the UPF+PGW-U for the second PDU session as UPF+PGW-U 1.

[0243] S413, the process for establishing a second PDU session by the terminal, RAN, AMF, SMF+PGW-C, UDM+HSS, PCF, and UPF+PGW-U is described in the prior art. To avoid redundancy, the embodiments of this application will not be described in detail here.

[0244] In one possible implementation, the AMF can carry a sixth indication information in the establishment request for the second PDU session sent to SMF+PGW-C1 in S411. This indication information indicates that the currently received second PDU session carrying DNN1 needs to select the same UPF+PGW-U as other PDU sessions carrying the same DNN1. Optionally, SMF+

[0245] PGW-C 1 queries the PDU session context of the terminal based on DNN1. If the DNN of the established first PDU session is the same as the DNN of the current second PDU session, then SMF+PGW-C 1 obtains the UPF+PGW-U 1 selected for the first PDU session from the context of the first PDU session and determines the UPF+PGW-U 1 selected for the first PDU session as the UPF+PGW-U 1 of the second PDU session. Optionally, SMF+PGW-C 1 determines the UPF+PGW-U of the second PDU session as UPF+PGW-U 1 based on the separately saved DNN1 and the UPF+PGW-U 1 corresponding to that DNN1.

[0246] The following describes the method 500 for determining the PDU session service network element in the second scenario, such as... Figure 5 As shown, method 500 includes;

[0247] S501, same as S401. The request to establish the first PDU session may also carry the first S-NSSAI.

[0248] S502, the AMF determines whether the PDU session corresponding to the first DNN needs to be selected to the same SMF+PGW-C, and determines the SMF+PGW-C of the first PDU session. Alternatively, the AMF determines whether the PDU session carrying the first DNN and the first S-NSSA needs to be selected to the same SMF+PGW-C, and determines the SMF+PGW-C of the PDU session carrying the first DNN and the first S-NSSA.

[0249] In this process, the AMF determines whether the PDU session corresponding to the first DNN needs to be selected to the same SMF+PGW-C, or the AMF determines whether the PDU session carrying the first DNN and the first S-NSSAI needs to be selected to the same SMF+PGW-C. The specific determination method can be found in the five methods in S404 of method 400.

[0250] When it is determined that the PDU session corresponding to the first DNN needs to select the same SMF+PGW-C, the AMF determines that the same SMF+PGW-C is also the SMF+PGW-C corresponding to the first PDU session. The AMF determines the same SMF+PGW-C based on whether the first PDU session is the first PDU session established for the first DNN, which can be divided into two cases:

[0251] In the first scenario, if the first PDU session is the first PDU session corresponding to the first DNN, then the AMF determines the SMF+PGW-C based on the S-NSSAI, DNN, terminal subscription information, and local operator policy of the first PDU session, and saves the correspondence between the DNN and the SMF+PGW-C.

[0252] Optionally, in the first case, the first PDU session can also be the PDU session corresponding to the first DNN and the first S-NSSAI that is established for the first time. In this case, the AMF determines the SMF+PGW-C based on the S-NSSAI, DNN, terminal subscription information and local operator policy of the first PDU session, and saves the correspondence between DNN, S-NSSAI and SMF+PGW-C.

[0253] In the second scenario, if the first PDU session is not the first PDU session corresponding to the first DNN, then the AMF will determine the SMF+PGW-C corresponding to the first DNN saved in the first scenario as the SMF+PGW-C of the first PDU session.

[0254] Optionally, in the second case, if the first PDU session is not the first PDU session corresponding to the first DNN and the first S-NSSAI established, then the AMF will determine the SMF+PGW-C corresponding to the first DNN and the first S-NSSAI saved in the first case as the SMF+PGW-C of the first PDU session.

[0255] S503, AMF sends a request to establish the first PDU session to SMF+PGW-C of the first PDU session. The request to establish the first PDU session carries the identifier of the first PDU session and the first DNN.

[0256] Optionally, the establishment request for the first PDU session may also carry at least one of the following information: terminal identifier, S-NSSAI, and SSC mode.

[0257] S504, SMF+PGW-C selects a UPF+PGW-U for the PDU session corresponding to the first DNN. The following describes two cases:

[0258] In the first scenario, if the scenario described in S502 exists, SMF+PGW-C determines whether the PDU session corresponding to the first DNN needs to select the same UPF+PGW-U based on at least one of the five methods in S404. If so, SMF+PGW-C can select a UPF+PGW-U for the PDU session corresponding to the first DNN based on the location information, load information, etc. of the UPF+PGW-U. For example, in S405, SMF+PGW-C saves the correspondence between the DNN and the selected UPF+PGW-U.

[0259] Optionally, if the first scenario in S502 exists, the SMF+PGW-C determines, based on at least one of the five methods in S404, whether the PDU session carrying the first DNN and the first S-NSSAI needs to select the same UPF+PGW-U. If so, the SMF+PGW-C can select a UPF+PGW-U for the PDU session carrying the first DNN and the first S-NSSAI based on the location information, load information, etc. of the UPF+PGW-U. For example, in S405, the SMF+PGW-C saves the correspondence between the first DNN, the first S-NSSAI, and the selected UPF+PGW-U.

[0260] In the second scenario, if the second scenario in S502 exists, then in the correspondence between the DNN and the selected UPF+PGW-U stored in the first scenario in S504, UPF+PGW-U is selected for the first PDU session.

[0261] Optionally, if the second case in S502 exists, then in the correspondence between the first DNN, the first S-NSSAI and the selected UPF+PGW-U saved in the first case in S504, UPF+PGW-U is selected for the first PDU session.

[0262] S505, the process of establishing the first PDU session by the terminal, RAN, AMF, SMF+PGW-C, UDM+HSS, PCF, and UPF+PGW-U is described in the prior art. To avoid redundancy, the embodiments of this application will not be described in detail here.

[0263] The following describes method 600 for determining the PDU session service network element in the second scenario. Unlike method 500, where the AMF determines whether the PDU session corresponding to the first DNN needs to be selected to the same SMF+PGW-C; in method 600, the AMF determines whether the PDU session corresponding to the first DNN needs to be selected to the same SMF+PGW-C and the same UPF+PGW-U. Alternatively, in method 500, the AMF determines whether the PDU session carrying the first DNN and the first S-NSSAI needs to be selected to the same SMF+PGW-C; in method 600, the AMF determines whether the PDU session carrying the first DNN and the first S-NSSAI needs to be selected to the same SMF+PGW-C and the same UPF+PGW-U. Figure 6 As shown, method 600 includes:

[0264] S601, same as S401.

[0265] S602, AMF determines whether the PDU session corresponding to the first DNN needs to select the same SMF+PGW-C and the same UPF+PGW-U, and determines the SMF+PGW-C of the first PDU session.

[0266] In this process, the AMF determines whether the PDU session corresponding to the first DNN needs to be selected to the same SMF+PGW-C and the same UPF+PGW-U. The five methods in S404 can be used to determine whether the PDU session corresponding to the first DNN needs to be selected to the same SMF+PGW-C and the same UPF+PGW-U.

[0267] When determining that the PDU session corresponding to the first DNN needs to select the same SMF+PGW-C and the same UPF+PGW-U, the AMF first determines the same SMF+PGW-C in the same way as S502 in method 500.

[0268] Optionally, S602 may be: the AMF determines whether the PDU session carrying the first DNN and the first S-NSSAI needs to be selected to the same SMF+PGW-C and the same UPF+PGW-U, and determines the SMF+PGW-C of the first PDU session.

[0269] In this process, the AMF determines whether the PDU session carrying the first DNN and the first S-NSSAI needs to be selected to the same SMF+PGW-C and the same UPF+PGW-U. The five methods in S404 can be used to determine whether the PDU session carrying the first DNN and the first S-NSSAI needs to be selected to the same SMF+PGW-C and the same UPF+PGW-U.

[0270] When it is determined that the PDU session carrying the first DNN and the first S-NSSAI needs to select the same SMF+PGW-C and the same UPF+PGW-U, the AMF first determines the same SMF+PGW-C in the same way as S502 in method 500.

[0271] In S603, the AMF sends a request to establish the first PDU session to the SMF+PGW-C determined in S602. The request to establish the first PDU session carries the identifier of the first PDU session and the first DNN.

[0272] Optionally, the first PDU session establishment request may also carry the terminal identifier, at least one of S-NSSAI and SSC modes.

[0273] Optionally, the establishment request for the first PDU session includes a sixth indication, which instructs the PDU session corresponding to the first DNN to select the same UFP+PGW-U. Alternatively, the sixth indication is used to instruct the PDU session carrying the first DNN and the first S-NSSAI to select the same UFP+PGW-U.

[0274] S604, SMF+PGW-C selects a UPF+PGW-U for the PDU session corresponding to the first DNN. For the specific method of selecting UPF+PGW-U, refer to S504 of method 500.

[0275] Optionally, in one possible implementation of step 3, if the first PDU session is the first PDU session established corresponding to the first DNN, the AMF can send the establishment request for the first PDU session to the SMF+PGW-C carrying the sixth indication information. In the establishment request for subsequent PDU sessions, the sixth indication information is not carried. After the SMF+PGW-C selects UPF+PGW-U, the correspondence between the DNN and UPF+PGW-U is saved. When the SMF+PGW-C receives the next PDU session corresponding to the first DNN, it selects the same UPF+PGW-U as the first PDU session.

[0276] Optionally, in another possible implementation of step 3, the AMF may carry a sixth indication information in each PDU session establishment request sent to the SMF+PGW-C. In this way, after receiving each PDU session establishment request, the SMF+PGW-C looks up the context of the PDU session based on the DNN, determines the PDU session with the same DNN, and identifies the UPF+PGW-U selected by the already established PDU session with the same DNN as the UPF+PGW-U of the current PDU session.

[0277] Optionally, in S604, SMF+PGW-C selects a UPF+PGW-U for the PDU session carrying the first DNN and the first S-NSSAI. For the specific method of selecting UPF+PGW-U, refer to S504 of method 500.

[0278] Optionally, in one possible implementation of S603, if the first PDU session is the first PDU session established carrying the first DNN and the first S-NSSAI, the AMF can send the establishment request for the first PDU session to the SMF+PGW-C with the sixth indication information. In subsequent PDU session establishment requests, the sixth indication information is not carried. After the SMF+PGW-C selects UPF+PGW-U, the correspondence between the first DNN and the first S-NSSAI and UPF+PGW-U is saved. When the SMF+PGW-C receives the next PDU session carrying the first DNN and the first S-NSSAI, it selects the same UPF+PGW-U as the first PDU session.

[0279] Optionally, in another possible implementation of S603, the AMF may carry sixth indication information in each PDU session establishment request sent to the SMF+PGW-C. In this way, after receiving each PDU session establishment request, the SMF+PGW-C looks up the context of the PDU session based on the DNN, determines the PDU session with the same DNN, and identifies the UPF+PGW-U of the already established PDU session with the first DNN and the first S-NSSAI as the UPF+PGW-U of the current PDU session.

[0280] S605, the process for establishing the first PDU session by the terminal, RAN, AMF, SMF+PGW-C, UDM+HSS, PCF, and UPF+PGW-U is described in the prior art. To avoid redundancy, the embodiments of this application will not be described in detail here.

[0281] It should be understood that the embodiments of this application do not impose any limitation on the order of the steps in methods 200 to 600 described above. The step number in each method does not represent the order of steps. In practical applications, the order of steps in each method can be adjusted. For example, the order of steps in each method can be determined according to the internal logic.

[0282] The above text combines Figures 2 to 6 The method for determining PDU session service network elements according to embodiments of this application is described in detail below. Figures 7 to 16 This application provides a detailed description of the apparatus and system for determining PDU session service network elements according to embodiments of the present application.

[0283] Figure 7 This application illustrates an apparatus 700 for determining a PDU session service network element, which includes:

[0284] The transceiver unit 710 is configured to receive a first PDU session establishment request from the mobility management device, wherein the first PDU session establishment request includes a first data network name (DNN).

[0285] Processing unit 720 is used to determine that the PDU session corresponding to the first DNN needs to select the same control plane function network element and the same user plane function network element;

[0286] The transceiver unit 710 is further configured to: send a first indication information to the mobility management device, the first indication information being used to indicate that the PDU session corresponding to the first DNN needs to select the same control plane function network element.

[0287] As an optional embodiment, the establishment request of the first PDU session further includes second indication information, which is used to indicate that the PDU session corresponding to the first DNN established by the terminal needs to select the same control plane function network element and the same user plane function network element; the processing unit 720 is specifically used to: determine, according to the second indication information, that the PDU session corresponding to the first DNN established by the terminal needs to select the same control plane function network element and the same user plane function network element.

[0288] As an optional embodiment, the second indication information is Session and Service Continuity (SSC) Mode 1.

[0289] As an optional embodiment, the processing unit 720 is further configured to: determine that the first PDU session needs to be switched to the evolved Packet Core (EPC) network before determining that the PDU session corresponding to the first DNN needs to select the same control plane function and the same user plane function network element.

[0290] As an optional embodiment, the processing unit 720 is further configured to: after determining that the PDU session corresponding to the first DNN needs to select the same control plane function network element and the same user plane function network element, allocate user plane function network elements to the first PDU session, and save the correspondence between the first DNN and the allocated user plane function network element.

[0291] As an optional embodiment, the transceiver unit 710 is further configured to: receive a second PDU session establishment request sent by the mobility management device, wherein the second PDU session establishment request includes the first DNN; the processing unit 720 is further configured to: determine the user plane function network element of the first PDU session as the user plane function network element of the second PDU session.

[0292] As an optional embodiment, the establishment request of the first PDU session may further include the first single network slice auxiliary information S-NSSAI; the PDU session corresponding to the first DNN is specifically a PDU session carrying the first DNN and the first S-NSSAI.

[0293] It should be understood that the device 700 here is embodied in the form of a functional unit. The term "unit" here can refer to an application-specific integrated circuit (ASIC), electronic circuitry, a processor (e.g., a shared processor, a proprietary processor, or a group processor, etc.) and memory for executing one or more software or firmware programs, combined logic circuitry, and / or other suitable components supporting the described functions. In an alternative example, those skilled in the art will understand that the device 700 can specifically be a control plane functional network element in the above method embodiments. The device 700 can be used to execute the various processes and / or steps corresponding to the control plane functional network element in the above method embodiments; to avoid repetition, these will not be described further here.

[0294] Figure 8 This application illustrates an apparatus 800 for determining a PDU session service network element, which includes:

[0295] The transceiver unit 810 is used to receive a second PDU session establishment request sent by the terminal, wherein the second PDU session establishment request carries a first data network name (DNN).

[0296] Processing unit 820 is configured to determine a first control plane function network element as the control plane function network element of the second PDU session based on a first correspondence set. The first correspondence set is used to indicate that the establishment requests of multiple PDU sessions carrying a specific DNN need to select the same specific control plane function network element. The first correspondence set includes the correspondence between the first DNN and the first control plane function network element.

[0297] The transceiver unit 810 is further configured to: send a request to establish the second PDU session to the first control plane functional network element.

[0298] As an optional embodiment, the transceiver unit 810 is further configured to: receive first indication information from the first control plane function network element, the first indication information being used to indicate that the PDU session corresponding to the first DNN needs to select the same control plane function network element; the processing unit 820 is further configured to save the correspondence between the first DNN and the first control plane function network element according to the first indication information.

[0299] As an optional embodiment, each element in the first correspondence set is used to indicate whether a DNN corresponds to a control plane function element and whether the PDU session corresponding to a DNN needs to select the same control plane function element.

[0300] As an optional embodiment, the establishment request of the second PDU session includes a fifth indication information, which is used to indicate that the PDU session corresponding to the first DNN needs to select the same user plane function network element.

[0301] It should be understood that the device 800 here is embodied in the form of a functional unit. The term "unit" here can refer to an application-specific integrated circuit (ASIC), electronic circuitry, a processor (e.g., a shared processor, a proprietary processor, or a group processor, etc.) and memory for executing one or more software or firmware programs, integrated logic circuitry, and / or other suitable components supporting the described functions. In an alternative example, those skilled in the art will understand that the device 800 can specifically be the mobility management device in the above method embodiments. The device 800 can be used to execute the various processes and / or steps corresponding to the mobility management device in the above method embodiments; to avoid repetition, these will not be described again here.

[0302] Figure 9 This application illustrates an apparatus 900 for determining a PDU session service network element, which includes:

[0303] The transceiver unit 910 is used to receive a first PDU session establishment request sent by the terminal, wherein the first PDU session establishment request includes a first data network name (DNN).

[0304] The processing unit 920 is used to determine whether the PDU session corresponding to the first DNN needs to select the same control plane function network element, or whether it needs to select the same control plane function network element and the same user plane function network element.

[0305] The processing unit 920 is further configured to determine that the first control plane function element is the control plane function element of the first PDU session.

[0306] As an optional embodiment, the processing unit 920 is further configured to: determine whether a PDU session with the same first DNN has already been established; if a PDU session with the same first DNN has already been established, the first control plane function network element is the control plane function network element of the established PDU session with the same first DNN.

[0307] As an optional embodiment, the establishment request of the first PDU session includes second indication information. The second indication information is used to indicate that the PDU session corresponding to the first DNN established by the terminal needs to select the same control plane function network element, or needs to select the same control plane function network element and the same user plane function network element. The processing unit is specifically used to: determine, according to the second indication information, that the PDU session corresponding to the first DNN established by the terminal needs to select the same control plane function network element, or needs to select the same control plane function network element and the same user plane function network element.

[0308] As an optional embodiment, the second indication information is Session and Service Continuity (SSC) Mode 1.

[0309] As an optional embodiment, if the processing unit 920 determines that the PDU session corresponding to the first DNN needs to select the same control plane function network element and the same user plane function network element, the transceiver unit 910: sends a fifth indication information to the first control plane function network element, the fifth indication information being used to indicate that the PDU session corresponding to the first DNN corresponds to the same user plane function network element.

[0310] As an optional embodiment, the establishment request of the first PDU session may further include the first single network slice auxiliary information S-NSSAI; the PDU session corresponding to the first DNN is specifically a PDU session carrying the first DNN and the first S-NSSAI.

[0311] As an optional embodiment, the processing unit 920 is further configured to: determine whether a PDU session carrying the first DNN and the first S-NSSAI has already been established; if a PDU session carrying the first DNN and the first S-NSSAI has already been established, the first control plane function network element is a control plane function network element that has already been established with the same first DNN and first S-NSSAI.

[0312] It should be understood that the device 900 here is embodied in the form of a functional unit. The term "unit" here can refer to an application-specific integrated circuit (ASIC), electronic circuitry, a processor (e.g., a shared processor, a proprietary processor, or a group processor, etc.) and memory for executing one or more software or firmware programs, integrated logic circuitry, and / or other suitable components supporting the described functions. In an alternative example, those skilled in the art will understand that the device 900 can specifically be the mobility management device in the above method embodiments. The device 900 can be used to execute the various processes and / or steps corresponding to the mobility management device in the above method embodiments; to avoid repetition, these will not be described again here.

[0313] Figure 10 An apparatus 1000 for determining a PDU session service network element is shown in an embodiment of this application. The apparatus 1000 includes:

[0314] The transceiver unit 1010 is used to receive a first PDU session establishment request sent by the mobility management device, wherein the first PDU session establishment request includes a first data network name (DNN).

[0315] Processing unit 1020 is used to determine that the PDU session corresponding to the first DNN needs to select the same user plane function network element;

[0316] The processing unit 1020 is further configured to: determine the first user plane function network element as the user plane function network element of the first PDU session.

[0317] As an optional embodiment, the processing unit 1020 is further configured to: determine whether a PDU session with the same first DNN has already been established; if a PDU session with the same first DNN has already been established, the first user plane function network element is the user plane function network element with the established PDU session having the same first DNN.

[0318] As an optional embodiment, the establishment request of the first PDU session includes second indication information, which is used to indicate that the PDU session corresponding to the first DNN established by the terminal needs to select the same user plane function network element.

[0319] The processing unit 1020 is specifically used to: determine, based on the second indication information, that the PDU session corresponding to the first DNN needs to select the same user plane function network element.

[0320] As an optional embodiment, the second indication information is Session and Service Continuity (SSC) Mode 1.

[0321] As an optional embodiment, the establishment request of the first PDU session may further include the first single network slice auxiliary information S-NSSAI; the PDU session corresponding to the first DNN is specifically a PDU session carrying the first DNN and the first S-NSSAI.

[0322] As an optional embodiment, the processing unit 1020 is further configured to: determine whether a PDU session carrying the first DNN and the first S-NSSAI has already been established; if a PDU session carrying the first DNN and the first S-NSSAI has already been established, the first user plane function network element is a user plane function network element that has already been established with the same first DNN and first S-NSSAI PDU session.

[0323] As an optional embodiment, before determining that the PDU session corresponding to the first DNN needs to select the same control plane function network element and the same user plane function network element, the processing unit 1020 is further configured to: determine that the first PDU session needs to be switched to the evolved packet core network (EPC) in the future.

[0324] It should be understood that the device 1000 here is embodied in the form of a functional unit. The term "unit" here can refer to an application-specific integrated circuit (ASIC), electronic circuitry, a processor (e.g., a shared processor, a proprietary processor, or a group processor, etc.) and memory for executing one or more software or firmware programs, integrated logic circuitry, and / or other suitable components supporting the described functions. In an alternative example, those skilled in the art will understand that the device 1000 can be specifically a control plane functional network element in the above method embodiments. The device 1000 can be used to execute the various processes and / or steps corresponding to the control plane functional network element in the above method embodiments; to avoid repetition, these will not be described further here.

[0325] Figure 11 A communication system 1100 provided in an embodiment of this application is shown. The system 1100 includes a device 700 and a device 800. Figure 12 A communication system 1200 provided in an embodiment of this application is shown. The system 1200 includes a device 900 and a device 1000.

[0326] The aforementioned device 700 completely corresponds to the control plane functional network elements in the embodiments of methods 200 and 400; the aforementioned device 800 completely corresponds to the mobility management equipment in the embodiments of methods 200 and 400; the aforementioned device 900 completely corresponds to the mobility management equipment in the embodiments of methods 300, 500, or 600; and the aforementioned device 1000 completely corresponds to the control plane functional network elements in the embodiments of methods 300, 500, or 600. The corresponding units execute the corresponding steps. For example, the transceiver unit executes the transceiver steps in the method embodiments. Other steps besides transceiver can be executed by the processing module. The functions of specific modules can be referred to the corresponding method embodiments, and will not be detailed further.

[0327] The devices 700-1000 of the above-described schemes have the function of implementing the corresponding steps executed by the control plane functional network elements and mobility management network elements in the above methods; the functions can be implemented by hardware or by hardware executing corresponding software. The hardware or software includes one or more modules corresponding to the above functions; for example, the transmitting unit can be replaced by a transmitter, the receiving unit can be replaced by a receiver, and other units, such as the determining unit, can be replaced by a processor, which respectively executes the transmission and reception operations and related processing operations in each method embodiment.

[0328] In the embodiments of this application, Figures 7-10 The device mentioned can also be a chip or a chip system, such as a System on Chip (SoC). Correspondingly, the receiving unit and the transmitting unit can be the transceiver circuits of the chip, and there is no limitation here.

[0329] Figure 13 This application illustrates another apparatus 1300 for determining a PDU service network element according to an embodiment of the present application. The apparatus 1300 includes a processor 1310, a transceiver 1320, and a memory 1330. The processor 1310, transceiver 1320, and memory 1330 communicate with each other via an internal connection path. The memory 1330 stores instructions, and the processor 1310 executes the instructions stored in the memory 1330 to control the transceiver 1320 to transmit and / or receive signals.

[0330] Transceiver 1320 is used to receive a first PDU session establishment request from mobility management equipment, the first PDU session establishment request including a first data network name (DNN); processor 1310 is used to determine that the PDU session corresponding to the first DNN needs to select the same control plane function network element and the same user plane function network element.

[0331] The transceiver 1320 is further configured to: send a first indication message to the mobility management device, the first indication message being used to indicate that the PDU session corresponding to the first DNN needs to select the same control plane function network element.

[0332] It should be understood that the device 1300 may specifically be a control plane function network element in the above method embodiments, and may be used to execute the various steps and / or processes corresponding to the control plane function network element in the above method embodiments. Optionally, the memory 1330 may include read-only memory and random access memory, and provide instructions and data to the processor. A portion of the memory may also include non-volatile random access memory. For example, the memory may also store device type information. The processor 1310 may be used to execute instructions stored in the memory, and when the processor 1310 executes instructions stored in the memory, the processor 1310 is used to execute the various steps and / or processes of the above method embodiments corresponding to the control plane function network element.

[0333] Figure 14 This application illustrates another apparatus 1400 for determining a PDU service network element according to an embodiment of the present application. The apparatus 1400 includes a processor 1410, a transceiver 1420, and a memory 1430. The processor 1410, transceiver 1420, and memory 1430 communicate with each other via an internal connection path. The memory 1430 stores instructions, and the processor 1410 executes the instructions stored in the memory 1430 to control the transceiver 1420 to transmit and / or receive signals.

[0334] The transceiver 1420 is used to receive a second PDU session establishment request sent by a terminal, the second PDU session establishment request carrying a first data network name (DNN); the processor 1410 is used to determine a first control plane function element as the control plane function element of the second PDU session according to a first correspondence set, the first correspondence set being used to indicate that multiple PDU session establishment requests carrying a specific DNN need to select the same specific control plane function element; wherein, the first correspondence set includes the correspondence between the first DNN and the first control plane function element. The transceiver 1420 is further used to: send the second PDU session establishment request to the first control plane function element.

[0335] It should be understood that the apparatus 1400 may specifically be the mobility management device in the above method embodiments, and may be used to execute the various steps and / or processes corresponding to the mobility management device in the above method embodiments. Optionally, the memory 1430 may include read-only memory and random access memory, and provide instructions and data to the processor. A portion of the memory may also include non-volatile random access memory. For example, the memory may also store device type information. The processor 1410 may be used to execute instructions stored in the memory, and when the processor 1410 executes instructions stored in the memory, the processor 1410 is used to execute the various steps and / or processes of the above method embodiments corresponding to the mobility management device.

[0336] Figure 15 This application illustrates another apparatus 1500 for determining a PDU service network element according to an embodiment of the present application. The apparatus 1500 includes a processor 1510, a transceiver 1520, and a memory 1530. The processor 1510, transceiver 1520, and memory 1530 communicate with each other via an internal connection path. The memory 1530 stores instructions, and the processor 1510 executes the instructions stored in the memory 1530 to control the transceiver 1520 to transmit and / or receive signals.

[0337] The transceiver 1520 is used to receive a first PDU session establishment request sent by the terminal, the first PDU session establishment request including a first data network name (DNN). The processor 1510 is used to determine whether the PDU session corresponding to the first DNN needs to select the same control plane function network element, or whether it needs to select the same control plane function network element and the same user plane function network element. The processor 1510 is further used to determine that the first control plane function network element is the control plane function network element of the first PDU session.

[0338] It should be understood that the apparatus 1500 may specifically be the mobility management device in the above method embodiments, and may be used to execute the various steps and / or processes corresponding to the mobility management device in the above method embodiments. Optionally, the memory 1530 may include read-only memory and random access memory, and provide instructions and data to the processor. A portion of the memory may also include non-volatile random access memory. For example, the memory may also store device type information. The processor 1510 may be used to execute the instructions stored in the memory, and when the processor 1510 executes the instructions stored in the memory, the processor 1510 is used to execute the various steps and / or processes of the above method embodiments corresponding to the mobility management device.

[0339] Figure 16This application illustrates another apparatus 1600 for determining a PDU service network element according to an embodiment of the present application. The apparatus 1600 includes a processor 1610, a transceiver 1620, and a memory 1630. The processor 1610, transceiver 1620, and memory 1630 communicate with each other via an internal connection path. The memory 1630 stores instructions, and the processor 1610 executes the instructions stored in the memory 1630 to control the transceiver 1620 to transmit and / or receive signals.

[0340] The transceiver 1620 is used to receive a first PDU session establishment request sent by the mobility management device, the first PDU session establishment request including a first data network name (DNN); the processor 1610 is used to determine that the PDU session corresponding to the first DNN needs to select the same user plane function network element; the processor 1610 is further used to: determine that the first user plane function network element is the user plane function network element of the first PDU session.

[0341] It should be understood that the device 1600 may specifically be a control plane function network element in the above method embodiments, and may be used to execute the various steps and / or processes corresponding to the control plane function network element in the above method embodiments. Optionally, the memory 1630 may include read-only memory and random access memory, and provide instructions and data to the processor. A portion of the memory may also include non-volatile random access memory. For example, the memory may also store device type information. The processor 1410 may be used to execute instructions stored in the memory, and when the processor 1610 executes instructions stored in the memory, the processor 1610 is used to execute the various steps and / or processes of the above method embodiments corresponding to the control plane function network element.

[0342] It should be understood that the transceiver described above may include a transmitter and a receiver. The transceiver may further include an antenna, and the number of antennas may be one or more. The memory may be a separate device or integrated into the processor. The various devices or some of the devices described above may be integrated into a chip, such as into a baseband chip.

[0343] In the embodiments of this application, Figures 13-16 The transceiver in this context can also be a communication interface; no specific limitation is made here.

[0344] In the embodiments of this application, the control plane functional network element can be a physical physical device or a virtual functional network element, and no limitation is made here.

[0345] In the various embodiments of this application, numerous examples have been provided for ease of understanding. However, these examples are merely illustrative and do not imply the best way to implement this application.

[0346] In the various embodiments of this application, for ease of description, the names of request messages, response messages, and other various messages are used. However, these messages are merely examples to illustrate the content to be carried or the functions to be implemented, and the specific names of the messages are not limited to this application. For example, they can also be first messages, second messages, third messages, etc. These messages can be specific messages or certain fields within messages. These messages can also represent various service operations.

[0347] It should also be understood that, in the embodiments of this application, the processor of the above-described device can be a central processing unit (CPU), or it can be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or any conventional processor.

[0348] In implementation, each step of the above method can be completed by integrated logic circuits in the processor's hardware or by instructions in software. The steps of the method disclosed in the embodiments of this application can be directly manifested as execution by a hardware processor, or as a combination of hardware and software units within the processor. The software units can reside in random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, or other mature storage media in the art. This storage medium is located in memory, and the processor executes the instructions in the memory, combining them with its hardware to complete the steps of the above method. To avoid repetition, detailed descriptions are omitted here.

[0349] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that integrates one or more available media. The available medium can be magnetic media (e.g., floppy disks, hard disks, magnetic tapes), optical media (e.g., DVDs), or semiconductor media (e.g., solid-state disks (SSDs)).

[0350] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0351] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0352] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0353] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0354] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0355] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0356] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for determining Protocol Data Unit (PDU) session service network elements, characterized in that, include: The control plane function network element receives a first PDU session establishment request sent by the mobility management device, wherein the first PDU session establishment request includes a first data network name (DNN). The control plane functional network element determines that the first PDU session needs to be subsequently switched to the evolved packet core network (EPC). The control plane function network element determines the first user plane function network element to be selected for the first PDU session based on the first DNN that the first PDU session will connect to. The control plane function network element selects the first user function network element for the first PDU session. The first PDU session is the session corresponding to the first DNN. The PDU session corresponding to the first DNN is one or more PDU sessions initiated by a terminal, or one or more PDU sessions initiated by different terminals. The first user plane function network element also serves as a user plane function network element connected to the established PDU session of the first DNN.

2. The method according to claim 1, characterized in that, The method further includes: The control plane functional network element determines whether a PDU session with the same first DNN has already been established; If a PDU session with the same first DNN has already been established, the first user plane function network element is the user plane function network element with the established PDU session having the same first DNN.

3. The method according to claim 1 or 2, characterized in that, The establishment request of the first PDU session includes second indication information, which is used to indicate that the PDU session corresponding to the first DNN established by the terminal needs to select the same user plane function network element. Wherein, the control plane function network element determines that the PDU session corresponding to the first DNN needs to select the same user plane function network element, including: The control plane function element determines, based on the second instruction information, that the first PDU session corresponding to the first DNN needs to select the same user plane function element.

4. The method according to claim 3, characterized in that, The second indication information is Session and Service Continuity (SSC) Mode 1.

5. The method according to claim 1 or 2, characterized in that, The establishment request for the first PDU session also includes the first single network slice auxiliary information S-NSSAI; the PDU session corresponding to the first DNN is specifically a PDU session carrying the first DNN and the first S-NSSAI.

6. The method according to claim 5, characterized in that, The method further includes: The control plane function network element determines whether a PDU session carrying the first DNN and the first S-NSSAI has been established. If a PDU session carrying the first DNN and the first S-NSSAI has already been established, the first user plane function network element is the user plane function network element that has already established a PDU session with the same first DNN and the first S-NSSAI.

7. The method according to claim 1 or 2, characterized in that, The step of determining the first user plane function network element for the first PDU session includes: The control plane function network element determines the first user plane function network element for the first PDU session based on the user's subscription data.

8. An apparatus for determining a Protocol Data Unit (PDU) session service network element, characterized in that, include: The transceiver unit is used to receive a first PDU session establishment request sent by the mobility management device. The first PDU session establishment request includes a first data network name (DNN) and a terminal identifier. The processing unit is used to determine that the first PDU session needs to be switched to the evolved packet core network (EPC) in the future, and to determine that the first PDU session needs to select the first user plane function network element based on the first DNN that the first PDU session will connect to. The processing unit is further configured to: select a first user plane function network element for the first PDU session, wherein the first PDU session is a session corresponding to the first DNN, and the PDU session corresponding to the first DNN is one or more PDU sessions initiated by a terminal, or one or more PDU sessions initiated by different terminals; the first user plane function network element is also used as a user plane function network element connected to the established PDU session of the first DNN.

9. The apparatus according to claim 8, characterized in that, The processing unit is also used for: Determine if a PDU session with the same first DNN has already been established; If a PDU session with the same first DNN has already been established, the first user plane function network element is the user plane function network element with the established PDU session having the same first DNN.

10. The apparatus according to claim 8 or 9, characterized in that, The establishment request of the first PDU session includes second indication information, which is used to indicate that the PDU session corresponding to the first DNN established by the terminal needs to select the same user plane function network element. The processing unit is specifically used for: Based on the second indication information, it is determined that the PDU session corresponding to the first DNN needs to select the same user plane function network element.

11. The apparatus according to claim 10, characterized in that, The second indication information is Session and Service Continuity (SSC) Mode 1.

12. The apparatus according to claim 8 or 9, characterized in that, The establishment request for the first PDU session also includes the first single network slice auxiliary information S-NSSAI; the PDU session corresponding to the first DNN is specifically a PDU session carrying the first DNN and the first S-NSSAI.

13. The apparatus according to claim 12, characterized in that, The processing unit is also used for: Determine whether a PDU session carrying the first DNN and the first S-NSSAI has already been established; If a PDU session with the first DNN and the first S-NSSAI has already been established, the first user plane function network element is a user plane function network element with an established PDU session with the same first DNN and the first S-NSSAI.

14. The apparatus according to claim 8 or 9, characterized in that, The processing unit is further used for: Based on the user's subscription data, the first user plane function network element is selected for the first PDU session.

15. A computer-readable storage medium having a computer program or instructions stored thereon, characterized in that, When the computer program or instructions are executed, the method as described in any one of claims 1 to 7 is performed.

16. A chip for determining a PDU session service network element, wherein instructions are stored thereon, characterized in that, When the chip is running on a control plane function network element or a mobility management device, the control plane function network element or the mobility management device performs the method as described in any one of claims 1 to 7.

17. A method for determining Protocol Data Unit (PDU) session service network elements, characterized in that, include: The mobility management device sends a first PDU session establishment request to the control plane function network element, the first PDU session establishment request including a first data network name (DNN); The control plane functional network element determines that the first PDU session needs to be subsequently switched to the evolved packet core network (EPC). The control plane function network element determines the first user plane function network element to be selected for the first PDU session based on the first DNN that the first PDU session will connect to. The control plane function network element selects the first user function network element for the first PDU session. The first PDU session is the session corresponding to the first DNN. The PDU session corresponding to the first DNN is one or more PDU sessions initiated by a terminal, or one or more PDU sessions initiated by different terminals. The first user plane function network element also serves as a user plane function network element connected to the established PDU session of the first DNN.

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