WO2021057600A1 - 网络切片选择的方法、设备及系统 - Google Patents

网络切片选择的方法、设备及系统 Download PDF

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Publication number
WO2021057600A1
WO2021057600A1 PCT/CN2020/115959 CN2020115959W WO2021057600A1 WO 2021057600 A1 WO2021057600 A1 WO 2021057600A1 CN 2020115959 W CN2020115959 W CN 2020115959W WO 2021057600 A1 WO2021057600 A1 WO 2021057600A1
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WIPO (PCT)
Prior art keywords
network
network slice
session
slice
information
Prior art date
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Ceased
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PCT/CN2020/115959
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English (en)
French (fr)
Inventor
朱方园
李永翠
李岩
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Huawei Technologies Co Ltd
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Huawei Technologies Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Huawei Technologies Co Ltd filed Critical Huawei Technologies Co Ltd
Priority to EP20867172.7A priority Critical patent/EP4024953A4/en
Priority to EP25189025.7A priority patent/EP4654667A3/en
Publication of WO2021057600A1 publication Critical patent/WO2021057600A1/zh
Priority to US17/701,663 priority patent/US12302233B2/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W48/00—Access restriction; Network selection; Access point selection
    • H04W48/18—Selecting a network or a communication service
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/0005—Control or signalling for completing the hand-off
    • H04W36/0011—Control or signalling for completing the hand-off for data sessions of end-to-end connection
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/13—Cell handover without a predetermined boundary, e.g. virtual cells
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/24—Reselection being triggered by specific parameters
    • H04W36/32—Reselection being triggered by specific parameters by location or mobility data, e.g. speed data
    • H04W36/322—Reselection being triggered by specific parameters by location or mobility data, e.g. speed data by location data
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W8/00—Network data management
    • H04W8/02—Processing of mobility data, e.g. registration information at HLR [Home Location Register] or VLR [Visitor Location Register]; Transfer of mobility data, e.g. between HLR, VLR or external networks

Definitions

  • This application relates to the field of communication technology, and in particular to a method, device and system for network slice selection.
  • a network slice is a logically isolated network used to support specific network capabilities and network characteristics. It can include the entire end-to-end (E2E) network, or part of the network functions can be in multiple network slices. Sharing is a key technology to meet the needs of the 5th generation (5G) mobile communication technology for network differentiation proposed by the 3rd generation partnership project (3GPP).
  • 5G 5th generation
  • 3GPP 3rd generation partnership project
  • the network characteristics of different network slices are not the same, and the network slices are required to be isolated from each other without affecting each other.
  • the network slicing of augmented reality (AR) or virtual reality (VR) services requires large bandwidth and low latency services
  • the network slicing of Internet of Things (IOT) services requires massive terminal access , But the bandwidth is small and there is no requirement for delay.
  • AR augmented reality
  • VR virtual reality
  • IOT Internet of Things
  • a terminal device may move out of the service area of a certain network slice.
  • PDU packet data unit
  • AMF access and mobility management functions
  • SMF session management function
  • the embodiments of the present application provide a method, device, and system for network slice selection, which are used to solve the problem that in the prior art, when a terminal device moves out of the service area of a certain network slice, if the terminal device has established a PDU associated with the network slice Session, the PDU session cannot maintain the continuity of the session.
  • a method for network slice selection includes: a mobility management network element determines that a first network slice in a visited network of a terminal device can serve a first session of the terminal device; a mobility management network The meta triggers the migration of the first session from the second network slice to the first network slice, where the second network slice is the network slice currently associated with the first session in the visited network.
  • the mobility management network element triggers the corresponding session management network element to execute the session release process.
  • the first network slice can serve the first session of the terminal device, which triggers the migration of the first session from the second network slice to the first network slice, so that the continuity of the session can be maintained.
  • the mobility management network element determines that the first network slice in the visited network of the terminal device can serve the first session of the terminal device, including: the mobility management network element determines that the terminal device has moved out of the terminal device.
  • the service range of the second network slice, and the terminal device is currently located in the service range of the first network slice; wherein, the first network slice and the third network slice have a mapping relationship, and the third network slice is the first session
  • the network slice associated with the home network of the terminal device can also be understood as: the mobility management network element determines that the terminal device has moved out of the first session. 2.
  • the service range of the network slice, and the mobility management network element determines that the first session is associated with a first network slice other than the second network slice in the visited network, which is not specifically limited in the embodiment of the present application. Based on this solution, the mobility management network element can determine that the first network slice in the visited network of the terminal device can serve the first session of the terminal device.
  • the method further includes: the mobility management network element sends first indication information to the first session management network element, where the first indication information is used to instruct the first session management network element to initiate the first session management network element.
  • a session modification process the mobility management network element receives the first information and the second information from the first session management network element, where the first information includes the identifier of the first session and the list of the first network slice Network slice selection auxiliary information S-NSSAI, the second information includes the identifier of the first session, the S-NSSAI of the first network slice, and the S-NSSAI of the third network slice;
  • the mobility management network element connects to the first The network access device sends the first information; and, the mobility management network element sends the second information to the terminal device, where the first information and the second information are used to update the first session in the visited network The corresponding S-NSSAI.
  • the terminal device and the first access network device can update the S-NSSAI corresponding to the first session in the visited network in time.
  • the mobility management network element determining that the first network slice in the visited network of the terminal device can serve the first session of the terminal device includes: the mobility management network element receives from the first access network Second indication information of the device, where the second indication information is used to indicate that the first network slice supported by the first access network device can serve the first session. Based on this solution, the mobility management network element can determine that the first network slice in the visited network of the terminal device can serve the first session of the terminal device.
  • the method further includes: the mobility management network element determines that the first session is in the visited network Is associated with other network slices except the second network slice, where the other network slices have a mapping relationship with the third network slice, and the other network slices include the first network slice, and the third network slice is the first network slice.
  • a session is associated with the network slice of the home network of the terminal device; the mobility management network element sends the single network slice selection auxiliary information S-NSSAI of the other network slice to the second access network device, where the second access The network device is an access network device that supports the second network slice. Based on this solution, the second access network device can learn information about other network slices other than the second network slice associated with the first session in the visited network.
  • the method further includes: the mobility management network element sends third indication information to the terminal device, where the third indication information is used to instruct the terminal device to initiate the service request process associated with the first session;
  • the service request process is used to establish an air interface resource of the first session, where the air interface resource is associated with the first network slice. Based on this solution, the air interface resources of the first session can be established.
  • the method further includes: the mobility management network element sending a first message to the first session management network element, the first message being used to request the first session management network element to establish the first session
  • the method further includes: the mobility management network element sending the S-NSSAI of the first network slice and the S-NSSAI of the third network slice corresponding to the identifier of the first session to the terminal device
  • the third network slice is a network slice associated with the home network of the terminal device for the first session. Based on this solution, the terminal device can update the S-NSSAI corresponding to the first session in the visited network in time.
  • the mobility management network element triggering the migration of the first session from the second network slice to the first network slice includes: the mobility management network element sends a second message to the first session management network element The second message is used to request the establishment of user plane resources between the first user plane network element and the third user plane network element, wherein the first session management network element serves the first network slice in the first network slice.
  • the session management network element of the session, the first user plane network element is the user plane network element serving the first session in the first network slice
  • the third user plane network element is the user plane network element serving the first session in the third network slice
  • the third network slice is a network slice associated with the first session in the home network of the terminal device. Based on this solution, user plane resources between the first user plane network element and the third user plane network element can be established.
  • the mobility management network element triggering the migration of the first session from the second network slice to the first network slice includes: the mobility management network element obtains the status of the first session in the third network slice Context information, the third network slice is the network slice associated with the first session in the home network of the terminal device; the mobility management network element sends a third message to the first session management network element, and the third message includes the first session Context information of a session in the third network slice, the third message is used to request the establishment of user plane resources between the first user plane network element and the third user plane network element, wherein the first session management network element Is a session management network element serving the first session in the first network slice, the first user plane network element is a user plane network element serving the first session in the first network slice, and the third user plane network element It is a user plane network element serving the first session in the third network slice. Based on this solution, user plane resources between the first user plane network element and the third user plane network element can be established.
  • the mobility management network element acquiring the context information of the first session in the third network slice includes: the mobility management network element sends a fourth message to the second session management network element, and the fourth The message is used to request the context information of the first session in the third network slice.
  • the second session management network element is the session management network element serving the first session in the second network slice; the mobility management network element receives information from Context information of the first session of the second session management network element in the third network slice.
  • the method further includes: the mobility management network element sends the updated allowed NSSAI, the S-NSSAI of the first network slice and the S-NSSAI of the third network slice to the terminal device.
  • Mapping relationship wherein the updated allowed NSSAI includes the S-NSSAI of the first network slice, and the third network slice is a network slice associated with the first session in the home network of the terminal device.
  • the terminal device can timely update the allowed NSSAI and learn the information of the network slices other than the second network slice associated with the first session in the visited network.
  • a method for network slice selection includes: a first access network device receives from a second access network device the single network slice selection auxiliary information S-NSSAI and the second network slice of the first network slice.
  • S-NSSAI of network slices where the first network slice and the second network slice are network slices in which the first session of the terminal device has a mapping relationship between the visited network of the terminal device and the third network slice, and the second network slice
  • the second network slice is the network slice currently associated with the first session in the visited network
  • the third network slice is the network slice associated with the first session in the home network of the terminal device
  • the first access network device determines not The second network slice is supported, and the first network slice is supported
  • the first access network device sends second indication information to the mobility management network element, and the second indication information is used to indicate that the first network slice can serve the first network slice.
  • the mobility management network element triggers the corresponding session management network element to execute the session release process.
  • the mobility management network element triggers the corresponding session management network element to execute the session release process.
  • the mobility management network element triggers the migration of the first session from the second network slice to the first network slice, so that Maintain the continuity of the conversation.
  • a communication device for implementing the above-mentioned various methods.
  • the communication device may be the mobility management network element in the aforementioned first aspect or the following thirteenth aspect, or a device containing the aforementioned mobility management network element; or, the communication device may be the aforementioned second aspect or the following first aspect.
  • the tenth aspect or the first access network device in the twelfth aspect below, or an apparatus containing the above-mentioned first access network device; or, the communication device may be the second access network device in the following eleventh aspect Equipment, or a device containing the above-mentioned second access network equipment.
  • the communication device includes a module, unit, or means corresponding to the foregoing method, and the module, unit, or means can be realized by hardware, software, or by hardware executing corresponding software.
  • the hardware or software includes one or more modules or units corresponding to the above-mentioned functions.
  • a communication device including: a processor and a memory; the memory is used to store computer instructions, and when the processor executes the instructions, the communication device executes the method described in any of the above aspects.
  • the communication device may be the mobility management network element in the aforementioned first aspect or the following thirteenth aspect, or a device containing the aforementioned mobility management network element; or, the communication device may be the aforementioned second aspect or the following first aspect.
  • the tenth aspect or the first access network device in the twelfth aspect below, or an apparatus containing the above-mentioned first access network device; or, the communication device may be the second access network device in the following eleventh aspect Equipment, or a device containing the above-mentioned second access network equipment.
  • a communication device including: a processor; the processor is configured to couple with a memory, and after reading an instruction in the memory, execute the method according to any of the foregoing aspects according to the instruction.
  • the communication device may be the mobility management network element in the aforementioned first aspect or the following thirteenth aspect, or a device containing the aforementioned mobility management network element; or, the communication device may be the aforementioned second aspect or the following first aspect.
  • the tenth aspect or the first access network device in the twelfth aspect below, or an apparatus containing the above-mentioned first access network device; or, the communication device may be the second access network device in the following eleventh aspect Equipment, or a device containing the above-mentioned second access network equipment.
  • a computer-readable storage medium stores instructions that, when run on a computer, enable the computer to execute the method described in any of the above or the following aspects.
  • a computer program product containing instructions which when running on a computer, enables the computer to execute the method described in any of the above or the following aspects.
  • a communication device for example, the communication device may be a chip or a chip system
  • the communication device includes a processor for implementing the functions involved in any of the above or the following aspects.
  • the communication device further includes a memory for storing necessary program instructions and data.
  • the communication device is a chip system, it may be composed of chips, or may include chips and other discrete devices.
  • the technical effect brought by any one of the third aspect to the eighth aspect can be referred to the above-mentioned first aspect or second aspect or third aspect or the tenth aspect to the thirteenth aspect of the different design methods. The technical effect of the coming will not be repeated here.
  • a communication system in a ninth aspect, includes a mobility management network element and a first access network device; the first access network device is configured to receive a first network slice from a second access network device The single network slice selection auxiliary information S-NSSAI and the second network slice S-NSSAI, where the first network slice and the second network slice are the first session of the terminal device in the visited network of the terminal device and the second network slice.
  • Three network slices A network slice with a mapping relationship, and the second network slice is the network slice currently associated with the first session in the visited network, and the third network slice is the home network of the first session in the terminal device
  • the associated network slice the first access network device is also used to determine that the second network slice is not supported, and the first network slice is supported; the first access network device is also used to send the second network slice to the mobility management network element Indication information, where the second indication information is used to indicate that the first network slice can serve the first session.
  • the mobility management network element is configured to receive the second indication information from the first access network device and trigger the migration of the first session from the second network slice to the first network slice.
  • the technical effects brought about by the ninth aspect can be referred to the technical effects brought about by the above-mentioned first aspect or the second aspect, which is not repeated here.
  • a method for network slice selection includes: a first access network device receives information about a first network slice from a second access network device, where the first network slice is a terminal device The network slice associated with the session; the first access network device determines that the first network slice is not supported; the first access network device determines the second network slice, wherein the first access network device supports the second network slice, And the second network slice has a mapping relationship with the first network slice; the first access network device sends indication information to the session management network element, the indication information is used to indicate that the second network slice can serve the session.
  • the first access network device can perform slice mapping to determine the first access network
  • the second network slice that has a mapping relationship with the first network slice supported by the device can trigger the migration of the session of the terminal device from the first network slice to the second network slice, thereby maintaining the continuity of the session.
  • determining the second network slice by the first access network device includes: the first access network device according to the information of the first network slice, and the mapping information between the second network slice and the first network slice , Determine the second network slice.
  • the network slice selection method provided in the embodiment of the present application may further include: the first access network device sends the information of the second network slice to the mobility management network element; the first access network device Receiving the mapping information between the second network slice and the first network slice from the mobility management network element. Based on this solution, the first access network device can obtain the mapping information between the second network slice and the first network slice.
  • a method for network slice selection includes: a second access network device determines information about a first network slice and information about a second network slice, wherein the first network slice is a terminal device The second network slice has a mapping relationship with the first network slice; the second access network device sends the information of the first network slice and the information of the second network slice to the first access network device information.
  • the existing Xn interface switching process if the first access network device does not support the network slice associated with the session of the terminal device, the session of the terminal device is refused to be switched to the target side, resulting in that the session cannot maintain session continuity on the target side , Affecting the business experience of terminal equipment.
  • the second access network device can send the first network to the first access network device
  • the slice information and the information of the second network slice that has a mapping relationship with the first network slice supported by the first access network device, so that the first access network device can obtain the information of the first network slice and the information of the second network slice , which can trigger the migration of the session of the terminal device from the first network slice to the second network slice, so that the continuity of the session can be maintained.
  • the second access network device determining the information of the first network slice and the information of the second network slice includes: the second access network device receives the information of the second network slice from the mobility management network element Information and information of the first network slice.
  • the information of the second network slice and the information of the first network slice can be determined by the mobility management network element.
  • the second access network device determining the information of the first network slice and the information of the second network slice includes: the second access network device receives the information of the first network slice from the mobility management network element Information; the second access network device determines the information of the second network slice according to the information of the first network slice and the mapping information between the second network slice and the first network slice.
  • the second access network device can know the mapping information between the second network slice and the first network slice in advance, and then after the second access network device receives the information of the first network slice from the mobility management network element , The second access network device may determine the information of the second network slice based on the mapping information.
  • the first network slice is the network slice in the network slice indicated by the network slice selection auxiliary information NSSAI allowed by the terminal device.
  • the network slice selection method provided in the embodiment of the present application may further include: The second access network device receives the mapping information from the mobility management network element. Based on this solution, the second access network device can learn the mapping information between the second network slice and the first network slice.
  • a method for network slice selection comprising: a first access network device receives information about a first network slice and information about a second network slice from a second access network device, wherein, The first network slice is a network slice associated with the session of the terminal device, and the second network slice has a mapping relationship with the first network slice; the first access network device determines that it does not support the first network slice, but supports the second network Slice: The first access network device sends indication information to the session management network element, where the indication information is used to indicate that the second network slice can serve the session.
  • the session of the terminal device is refused to be switched to the target side, resulting in that the session cannot maintain session continuity on the target side , Affecting the business experience of terminal equipment.
  • the network slice selection method provided in the embodiments of the present application, even if the first access network device does not support the network slice associated with the session of the terminal device, because the first access network device can obtain the information of the first network slice and the first connection
  • the information of the second network slice that has a mapping relationship with the first network slice supported by the network access device can trigger the migration of the session of the terminal device from the first network slice to the second network slice, so the continuity of the session can be maintained.
  • a method for selecting a network slice includes: a mobility management network element determining information about a first network slice and information about a second network slice, wherein the second network slice is identical to the first network slice.
  • the network slice has a mapping relationship; the mobility management network element sends the mapping information of the first network slice and the second network slice to the access network device.
  • the first access network device can obtain the information of the first network slice and the first connection
  • the information of the second network slice that has a mapping relationship with the first network slice supported by the network access device can trigger the migration of the session of the terminal device from the first network slice to the second network slice, thereby maintaining the continuity of the session.
  • the mobility management network element determines the information of the first network slice and the information of the second network slice, including: the mobility management network element determines the information of the first network slice; the mobility management network element determines the information of the first network slice according to the The information of the first network slice and the mapping information of the second network slice and the first network slice are used to determine the information of the second network slice.
  • the first network slice is a network slice supported by the access network device.
  • the access network device can obtain the slice mapping information of the network slice supported by the access network device.
  • the first network slice is a network slice associated with a session of the terminal device.
  • the access network device can obtain the slice mapping information of the network slice associated with the session of the terminal device.
  • the first network slice is the network slice indicated by the network slice selection auxiliary information NSSAI allowed by the terminal device.
  • the access network device can obtain the slice mapping information of the network slice indicated by the NSSAI allowed by the terminal device.
  • the second network slice has a mapping relationship with the first network slice, including: the first network slice and the second network slice
  • the network slice can provide the same service type; or, the first network slice and the second network slice can share a network slice instance.
  • a communication system in a fourteenth aspect, includes a first access network device and a second access network device.
  • the second access network device is configured to send information of the first network slice to the first access network device, where the first network slice is a network slice associated with a session of the terminal device.
  • the first access network device is configured to receive information about the first network slice from the second access network device, and determine that the first access network device does not support the first network slice.
  • the first access network device is further configured to determine a second network slice, where the first access network device supports the second network slice, and the second network slice has a mapping relationship with the first network slice; the first access network device , Is also used to send instruction information to the session management network element, where the instruction information is used to indicate that the second network slice can serve the session.
  • the technical effects brought about by the fourteenth aspect can be referred to the technical effects brought about by the tenth aspect above, which will not be repeated here.
  • a communication system in a fifteenth aspect, includes a first access network device and a second access network device.
  • the second access network device is used to determine the information of the first network slice and the information of the second network slice, where the first network slice is a network slice associated with the session of the terminal device, and the second network slice has the same characteristics as the first network slice. Mapping relationship; the second access network device is also used to send the information of the first network slice and the information of the second network slice to the first access network device.
  • the first access network device is used to receive the information of the first network slice and the information of the second network slice from the second access network device, and determine that the first access network device does not support the first network slice and supports the second network slice. Network slicing.
  • the first access network device is further configured to send instruction information to the session management network element, where the instruction information is used to indicate that the second network slice can serve the session.
  • the technical effects brought about by the fifteenth aspect can be referred to the technical effects brought about by the eleventh aspect or the twelfth aspect, which will not be repeated here.
  • FIG. 1 is a first structural diagram of a communication system provided by an embodiment of this application.
  • Fig. 2a is a second structural diagram of a communication system provided by an embodiment of this application.
  • FIG. 2b is a third structural diagram of a communication system provided by an embodiment of this application.
  • FIG. 3a is a schematic diagram of a possible network architecture corresponding to the communication system shown in FIG. 2a provided by an embodiment of this application;
  • FIG. 3b is a schematic diagram of a possible network architecture corresponding to the communication system shown in FIG. 2b according to an embodiment of the application;
  • FIG. 4 is a schematic structural diagram of a communication device provided by an embodiment of this application.
  • FIG. 5 is a schematic flowchart of a method for network slice selection according to an embodiment of this application.
  • FIG. 6 is a schematic flowchart of another network slice selection method provided by an embodiment of this application.
  • FIG. 7 is a schematic diagram 1 of interaction of a method for network slice selection according to an embodiment of this application.
  • FIG. 8 is a schematic diagram of the N9 tunnel before and after the first session migration according to an embodiment of the application.
  • FIG. 9 is a second schematic diagram of interaction of a method for network slice selection according to an embodiment of this application.
  • FIG. 10 is a third schematic diagram of interaction of a method for selecting a network slice according to an embodiment of this application.
  • FIG. 11 is a fourth schematic diagram of interaction of a method for selecting a network slice according to an embodiment of this application.
  • FIG. 12 is a schematic structural diagram of a mobility management network element provided by an embodiment of this application.
  • FIG. 13 is a schematic structural diagram of a first access network device provided by an embodiment of this application.
  • FIG. 14 is a fourth structural diagram of a communication system provided by an embodiment of this application.
  • 15 is a schematic diagram of an example of a multi-slice shared network provided by an embodiment of the application.
  • FIG. 16 is a schematic diagram of a possible network architecture corresponding to the communication system shown in FIG. 14 provided by an embodiment of this application;
  • FIG. 17 is a schematic diagram of a cross-slice movement scene provided by an embodiment of the application.
  • 18 is a schematic diagram 5 of interaction of a method for network slice selection according to an embodiment of this application.
  • 19 is a sixth schematic diagram of interaction of a method for network slice selection provided by an embodiment of this application.
  • 20 is a schematic diagram 7 of interaction of a method for network slice selection according to an embodiment of this application.
  • FIG. 21 is a schematic flowchart of another method for network slice selection according to an embodiment of this application.
  • FIG. 22 is a schematic flowchart of another method for network slice selection according to an embodiment of this application.
  • FIG. 23 is a schematic flowchart of another method for network slice selection according to an embodiment of this application.
  • FIG. 24 is a schematic flowchart of another method for network slice selection according to an embodiment of this application.
  • FIG. 25 is a schematic structural diagram of a second access network device provided by an embodiment of this application.
  • At least one item (a) refers to any combination of these items, including any combination of a single item (a) or a plurality of items (a).
  • at least one of a, b, or c can mean: a, b, c, ab, ac, bc, or abc, where a, b, and c can be single or multiple .
  • words such as “first” and “second” are used to distinguish the same or similar items with substantially the same function and effect.
  • words such as “first” and “second” do not limit the quantity and execution order, and words such as “first” and “second” do not limit the difference.
  • words such as “exemplary” or “for example” are used as examples, illustrations, or illustrations. Any embodiment or design solution described as “exemplary” or “for example” in the embodiments of the present application should not be construed as being more preferable or advantageous than other embodiments or design solutions.
  • words such as “exemplary” or “for example” are used to present related concepts in a specific manner to facilitate understanding.
  • a communication system 10 provided by an embodiment of this application.
  • the communication system 10 is applied in a roaming scenario, where the first session of the terminal device is migrated from the second network slice to the first network slice.
  • the first network slice and the second network slice are network slices in which the first session of the terminal device is in the visited network of the terminal device and the third network slice has a mapping relationship, and the second network slice is the first session in the visited network
  • the currently associated network slice, and the third network slice is a network slice associated with the home network of the terminal device for the first session.
  • the communication system 10 includes a mobility management network element and a first session management network element.
  • the mobility management network element and the first session management network element are located in the visited network of the terminal device.
  • the first session management network element is a session management network element serving the first session in the first network slice.
  • the communication system 10 may further include a second session management network element, a third session management network element, a first user plane network element, a second user plane network element, and a third user plane network element.
  • Element or one or more of the network elements of the network slice selection function.
  • the second session management network element, the first user plane network element, the second user plane network element, and the network slice selection function network element are located in the visited network of the terminal device, and the third session management network element and the third user plane network The element is located in the home network of the terminal device.
  • the second session management network element is a session management network element serving the first session in the second network slice;
  • the third session management network element is a session management network element serving the first session in the third network slice, and the first user plane network element Is the user plane network element serving the first session in the first network slice, the second user plane network element is the user plane network element serving the first session in the second network slice, and the third user plane network element is the user plane network element in the third network slice User plane network element serving the first session.
  • the communication system 10 may also include a first access network device.
  • the terminal device accesses the core network through the first access network device, and the first access network device can communicate with the second user plane network element; after the migration of the first session, the terminal device By accessing the core network through the first access network device, the first access network device can communicate with the first user plane network element.
  • the access network device connected to the terminal device changes.
  • the communication system 10 may also include a first access network device and a second access network device.
  • the terminal device accesses the core network through the second access network device, and the second access network device can communicate with the second user plane network element; after the migration of the first session, the terminal device An access network device accesses the core network, and the first access network device can communicate with the first user plane network element.
  • the first access network device is different from the second access network device.
  • the communication system 140 is applied to the Xn interface switching process in roaming or non-roaming scenarios, and can make the session of the terminal device successfully migrate from the associated network slice to the network slice that has a mapping relationship with the network slice associated with the terminal device, thereby making the The session maintains session continuity on the target side, where the target access network device supports network slices in which the network slices associated with the terminal device have a mapping relationship.
  • the second network slice is the same as the first network slice.
  • the mapping relationship includes: the first network slice and the second network slice can provide the same service type; or, the first network slice and the second network slice can share network slice instances, which are explained here in a unified manner, and will not be repeated in the following.
  • the mapping relationship between slice A and slice X means one or more of the following:
  • Slice A and slice X provide the same service type, that is, slice A can provide the service type provided by slice X.
  • the single network slice selection assistance information (single network slice selection assistance information, S-NSSAI)-a component slice/service type (Slice/Service type, SST) of slice A and the identifier S of slice X -NSSAI-X contains the same SST, but the component of S-NSSAI-A, the slice differentiator (SD), is different from the SD contained in S-NSSAI-X. Since the SD is different but the SST is the same, indicating that S-NSSAI-A and S-NSSAI-X are different, but can provide the same service type, slice A may have a mapping relationship with slice X.
  • Slice A and slice X can share network slice instances. Specifically, for example, a network slice instance (network slice instance) in the network can serve both slice A and slice X.
  • the anchor point network element belongs to the network slice instance shared by slice A and slice X
  • the anchor point network element can serve slice A and slice X.
  • the anchor point of the session is located at slice X. If the terminal device moves out of the coverage of slice X, because slice A and There is a mapping relationship for slice X, and the terminal device can connect to the anchor point of the session by accessing slice A to ensure the business continuity of the session.
  • the communication system 140 includes a first access network device and a second access network device, where the first access network device is the access of the terminal device after the session transfer.
  • the network equipment may also be referred to as the target access network equipment; the second access network equipment is the access network equipment accessed before the session transfer of the terminal equipment, and may also be referred to as the source access network equipment.
  • the terminal device accesses the core network through the second access network device; after the session of the terminal device is migrated, the terminal device accesses the core network through the first access network device.
  • the communication system 140 may further include one or more of a mobility management network element, a session management network element, a user plane network element, or a network slice selection function network element.
  • a mobility management network element a session management network element, a user plane network element, or a network slice selection function network element.
  • the connection mode of the terminal device, the first access network device, the second access network device, the mobility management network element, the session management network element, the user plane network element, or the network slice selection function network element can refer to Figure 14. This will not be repeated here.
  • the terminal device in the embodiments of the present application may be a device used to implement wireless communication functions, such as a terminal or a chip that can be used in a terminal, etc., which may be deployed on land, including indoor or outdoor, handheld or vehicle-mounted ; It can also be deployed on the water surface (such as ships, etc.); it can also be deployed in the air (such as airplanes, balloons, and satellites, etc.).
  • a terminal or a chip that can be used in a terminal, etc.
  • the terminal device in the embodiments of the present application may be a device used to implement wireless communication functions, such as a terminal or a chip that can be used in a terminal, etc., which may be deployed on land, including indoor or outdoor, handheld or vehicle-mounted ; It can also be deployed on the water surface (such as ships, etc.); it can also be deployed in the air (such as airplanes, balloons, and satellites, etc.).
  • the terminal may be a user equipment (UE), an access terminal, a terminal unit, a terminal station, a mobile station, a mobile station, a user equipment (UE), an access terminal, a terminal unit, a terminal station, a mobile station, and a mobile station in a 5G network or a public land mobile network (PLMN) that will be evolved in the future.
  • UE user equipment
  • PLMN public land mobile network
  • the access terminal can be a cellular phone, a cordless phone, a session initiation protocol (SIP) phone, a wireless local loop (WLL) station, a personal digital assistant (PDA), with wireless communication Functional handheld devices, computing devices or other processing devices connected to wireless modems, vehicle-mounted devices or wearable devices, virtual reality (VR) terminal devices, augmented reality (AR) terminal devices, industrial control (industrial) Wireless terminal in control), wireless terminal in self-driving (self-driving), wireless terminal in remote medical (remote medical), wireless terminal in smart grid (smart grid), wireless terminal in transportation safety (transportation safety) Terminals, wireless terminals in smart cities, wireless terminals in smart homes, etc.
  • the terminal can be mobile or fixed.
  • the radio access network (RAN) device (including the first access network device or the second access network device) in this embodiment of the application is a device that provides wireless communication functions for terminal devices .
  • the access network equipment includes, but is not limited to: next-generation base stations (gnodeB, gNB), evolved node B (evolved node B, eNB), radio network controller (RNC), node B (node B) in 5G, for example.
  • B base station controller
  • BSC base transceiver station
  • BTS home base station
  • base station for example, home evolved nodeB, or home node B, HNB
  • baseband unit baseBand unit, BBU
  • TRP transmission point
  • TP transmission point
  • mobile switching center etc.
  • the mobility management network element in the embodiment of the present application is mainly used for mobility management in a mobile network, such as user location update, user registration network, user handover, and so on.
  • mobility management network elements can be access and mobility management function (AMF) network elements.
  • AMF mobility management function
  • Namf is a service-based interface provided by AMF network elements.
  • AMF network elements can use Namf
  • the mobility management network element may still be an AMF network element or have other names, which is not limited in the embodiment of the present application.
  • the session management network element (including the first session management network element, the second session management network element, or the third session management network element) in the embodiment of the present application is mainly used for session management in the mobile network, such as session management. Create, modify, and release. Specific functions include assigning Internet Protocol (IP) addresses to users, selecting user plane network elements that provide message forwarding functions, and so on.
  • IP Internet Protocol
  • a session management network element may be a session management function (session management function, SMF) network element.
  • Nsmf is a service-based interface provided by SMF, and SMF can communicate with other network functions through Nsmf.
  • the session management network element may still be an SMF network element or have other names, which is not limited in the embodiment of this application.
  • the user plane network elements (including the first user plane network element, the second user plane network element, or the third user plane network element) in the embodiment of the present application are mainly used to execute the user according to the routing rules of the session management network element. Forwarding of data packets.
  • the user management network element may be a user plane function (UPF) network element.
  • UPF user plane function
  • future communications such as 6G communication
  • the user management network element may still be a UPF network element, or have other names. The application embodiment does not limit this.
  • the network slice selection function network element in the embodiment of the present application is used to select network slices for terminal devices, etc.
  • the network slice selection function network element can be a network slice selection function (NSSF) network element, where Nnssf is a service-based interface provided by the NSSF network element, and the NSSF network element can communicate with other network elements through Nnssf. Network function communication.
  • Nnssf network slice selection function
  • the network slice selection function network element may still be an NSSF network element or have other names, which is not limited in the embodiment of the present application.
  • FIG. 3a a possible schematic diagram of a network architecture corresponding to the communication system shown in FIG. 2a applicable to the embodiment of this application, as shown in FIG. 3b, is applicable to this embodiment of the application
  • the network element or entity corresponding to the mobility management network element may be the AMF network element in the 5G communication system
  • the network element or entity corresponding to the first session management network element may be the first visited SMF in the 5G communication system (visited SMF, V-SMF) network element
  • the network element or entity corresponding to the second session management network element may be the second V-SMF network element in the 5G communication system
  • the entity may be the home SMF (home SMF, H-SMF) network element in the 5G communication system
  • the network element or entity corresponding to the first user plane network element may be the first visited UPF (visited) network element in the 5G communication system.
  • the network element or entity corresponding to the second user plane network element may be the second V-UPF network element in the 5G communication system
  • the network element or entity corresponding to the third user plane network element It can be the home UPF (home UPF, H-UPF) network element in the 5G communication system
  • the network element or entity corresponding to the network slice selection function network element can be the NSSF network element in the 5G communication system
  • the first access network The network element or entity corresponding to the device may be the first RAN device in the 5G communication system
  • the network element or entity corresponding to the second access network device may be the second RAN device in the 5G communication system.
  • the network element or entity corresponding to the mobility management network element may be the AMF network element in the 5G communication system
  • the network element or entity corresponding to the session management network element may be the SMF network element in the 5G communication system, or the user plane network.
  • the network element or entity corresponding to the element may be a UPF network element in the 5G communication system
  • the network element or entity corresponding to the network slice selection function network element may be an NSSF network element in the 5G communication system.
  • the corresponding network element or entity may be the first RAN device (also referred to as the target RAN device) in the 5G communication system, and the network element or entity corresponding to the second access network device may be the second RAN device in the 5G communication system.
  • RAN equipment also referred to as source RAN equipment).
  • the N1 interface in Figure 3a or Figure 3b or Figure 16 is the reference point between the terminal equipment and the AMF network element;
  • the N2 interface is the connection between the RAN equipment and the AMF network element (for example, between the first RAN equipment and the AMF network element).
  • N3 interface is between the RAN device and the V-UPF network element (for example, between the first RAN device and the first V-UPF network element, between the first RAN device and the second V-UPF network element, and the second RAN device and Between the second V-UPF network element) or between the RAN device and the UPF network element (as shown in Figure 16 between the first RAN device and the UPF network element, between the second RAN device and the UPF network element) Reference point, used to transmit user plane data, etc.; N4 interface is between SMF network element and UPF network element (such as between the first V-SMF network element and the first V-UPF network element, or the second V-SMF The reference point between the network element and the second V-UPF network element, or between the H-SMF network element and the H-UPF network element, or between the SMF
  • N9 interface is between UPF network element and UPF network element (for example, between the first V-UPF network element and H-UPF network element, or A reference point between the second V-UPF network element and the H-UPF network element).
  • the AMF network element, SMF network element shown in Figure 3a or Figure 3b or Figure 16 (such as the first V-SMF network element or the second V-SMF network element or H-SMF network element or the SMF network element in Figure 16
  • Control plane network elements such as NSSF network elements and NSSF network elements
  • NSSF network elements and NSSF network elements can interact with service-oriented interfaces.
  • the service-oriented interface provided by the AMF network element to the outside can be Namf
  • the service-oriented interface provided by the SMF network element can be Nsmf
  • the service-oriented interface provided by the PCF network element can be Npcf
  • the service interface provided by the NSSF network element Can be Nnssf.
  • the visited security edge protection proxy (vSEPP) in Figure 3a or Figure 3b is used for terminal equipment’s visited public land mobile network (visited public land mobile network, VPLMN) internal control plane interface information Filtering and policy control, as well as topology hiding, etc.;
  • the home security edge protection proxy (hSEPP) in Figure 3a or Figure 3b is used for the home public land mobile network (HPLMN) of terminal equipment ) Information filtering and policy control of the internal control plane interface, as well as topology hiding, etc.; vSEPP and hSEPP are connected through the N32 interface (N32 for short).
  • the aforementioned H-SMF network element can also be referred to as an anchor SMF network element
  • the aforementioned H-UPF network element can also be referred to as an anchor UPF network element
  • the aforementioned first V-UPF network element It can also be called new (new)
  • the above-mentioned second V-UPF network element may also be referred to as an old (old) V-UPF network element
  • the above-mentioned first V-SMF network element may also be referred to as a new V-SMF network element
  • the foregoing second V-SMF network element may also be referred to as an old V-SMF network element, which is not specifically limited in the embodiment of the present application.
  • the mobility management network element, the session management network element, the first access network device, the second access network device, the first session management network element, the second session management network element, and the The three-session management network element, the first user plane network element, the second user plane network element, the third user plane network element, or the network slice selection function network element can also be called a communication device, which can be a general-purpose device or A dedicated device, which is not specifically limited in the embodiment of this application.
  • the mobility management network element, the session management network element, the first access network device, the second access network device, the first session management network element, the second session management network element, and the The related functions of the three-session management network element, the first user plane network element, the second user plane network element, the third user plane network element, or the network slice selection function network element can be implemented by one device or shared by multiple devices Implementation may also be implemented by one or more functional modules in a device, which is not specifically limited in the embodiment of the present application. It is understandable that the above functions can be network elements in hardware devices, software functions running on dedicated hardware, or a combination of hardware and software, or instantiated on a platform (for example, a cloud platform) Virtualization function.
  • a platform for example, a cloud platform
  • FIG. 4 is a schematic structural diagram of a communication device 400 provided by an embodiment of the application.
  • the communication device 400 includes one or more processors 401, a communication line 402, and at least one communication interface (in FIG. 4, the communication interface 404 and one processor 401 are taken as an example for illustration), optional
  • the memory 403 may also be included.
  • the processor 401 can be a general-purpose central processing unit (central processing unit, CPU), a microprocessor, an application-specific integrated circuit (ASIC), or one or more programs used to control the execution of the program of this application. integrated circuit.
  • CPU central processing unit
  • ASIC application-specific integrated circuit
  • the communication line 402 may include a path for connecting different components.
  • the communication interface 404 may be a transceiver module for communicating with other devices or communication networks, such as Ethernet, RAN, wireless local area networks (WLAN), and so on.
  • the transceiver module may be a device such as a transceiver or a transceiver.
  • the communication interface 404 may also be a transceiver circuit located in the processor 401 to implement signal input and signal output of the processor.
  • the memory 403 may be a device having a storage function.
  • it can be read-only memory (ROM) or other types of static storage devices that can store static information and instructions, random access memory (RAM), or other types that can store information and instructions
  • Dynamic storage devices can also be electrically erasable programmable read-only memory (EEPROM), compact disc read-only memory (CD-ROM) or other optical disk storage, optical disc storage ( Including compact discs, laser discs, optical discs, digital versatile discs, Blu-ray discs, etc.), magnetic disk storage media or other magnetic storage devices, or can be used to carry or store desired program codes in the form of instructions or data structures and can be stored by a computer Any other media taken, but not limited to this.
  • the memory can exist independently and is connected to the processor through the communication line 402. The memory can also be integrated with the processor.
  • the memory 403 is used to store computer-executed instructions for executing the solution of the present application, and the processor 401 controls the execution.
  • the processor 401 is configured to execute computer-executable instructions stored in the memory 403, so as to implement the network slice selection method provided in the embodiment of the present application.
  • the processor 401 may also perform processing-related functions in the network slice selection method provided in the following embodiments of the present application, and the communication interface 404 is responsible for communicating with other devices or communication networks.
  • the embodiments of this application do not specifically limit this.
  • the computer-executable instructions in the embodiments of the present application may also be referred to as application program codes, which are not specifically limited in the embodiments of the present application.
  • the processor 401 may include one or more CPUs, such as CPU0 and CPU1 in FIG. 4.
  • the communication device 400 may include multiple processors, such as the processor 401 and the processor 408 in FIG. 4. Each of these processors can be a single-core processor or a multi-core processor.
  • the processor here may include but is not limited to at least one of the following: central processing unit (CPU), microprocessor, digital signal processor (DSP), microcontroller (microcontroller unit, MCU), or artificial intelligence
  • CPU central processing unit
  • DSP digital signal processor
  • MCU microcontroller unit
  • computing devices such as processors that run software.
  • Each computing device may include one or more cores for executing software instructions to perform operations or processing.
  • the communication device 400 may further include an output device 405 and an input device 406.
  • the output device 405 communicates with the processor 401, and can display information in a variety of ways.
  • the output device 405 may be a liquid crystal display (LCD), a light emitting diode (LED) display device, a cathode ray tube (CRT) display device, or a projector (projector) Wait.
  • the input device 406 communicates with the processor 401, and can receive user input in a variety of ways.
  • the input device 406 may be a mouse, a keyboard, a touch screen device, a sensor device, or the like.
  • the aforementioned communication device 400 may sometimes be referred to as a communication device, which may be a general-purpose device or a special-purpose device.
  • the communication device 400 may be a desktop computer, a portable computer, a network server, a personal digital assistant (PDA), a mobile phone, a tablet computer, a wireless terminal device, an embedded device, the foregoing terminal device, the foregoing network device, or a picture 4 similar structure equipment.
  • PDA personal digital assistant
  • the embodiment of the present application does not limit the type of the communication device 400.
  • a method for network slice selection provided by an embodiment of this application, the method includes the following steps:
  • the mobility management network element determines that the first network slice in the visited network of the terminal device can serve the first session of the terminal device.
  • the mobility management network element determines that the first network slice in the visited network of the terminal device can serve the first session of the terminal device, including: the mobility management network element determines that the terminal device has moved out of the second network The service range of the slice, and the terminal device is currently located within the service range of the first network slice.
  • the mobility management network element determines that the first session of the terminal device is associated with the first network slice in the visited network.
  • the first network slice and the third network slice have a mapping relationship
  • the third network slice is a network slice associated with the home network of the terminal device of the first session. This will be further described in conjunction with Figure 7, Figure 9, and Figure 10 below.
  • the mobility management network element determining that the first network slice in the visited network of the terminal device can serve the first session of the terminal device includes: the mobility management network element receives from the first access network The first indication information of the device, where the first indication information is used to indicate that the first network slice supported by the first access network device can serve the first session. This will be further described in conjunction with Figure 11 below.
  • the mobility management network element triggers the migration of the first session from the second network slice to the first network slice, where the second network slice is a network slice currently associated with the first session in the visited network.
  • the mobility management network element triggering the migration of the first session from the second network slice to the first network slice includes: the mobility management network element sends a first message to the first session management network element, and the first The message is used to request the establishment of user plane resources between the first user plane network element and the third user plane network element. This will be further described in conjunction with "Method 1" in Figure 7 below.
  • the mobility management network element triggering the migration of the first session from the second network slice to the first network slice includes: the mobility management network element obtains context information of the first session in the third network slice, The third network slice is the network slice associated with the first session in the home network of the terminal device; the mobility management network element sends a second message to the first session management network element, and the second message includes that the first session is in the third network The context information of the slice.
  • the second message is used to request the establishment of user plane resources between the first user plane network element and the third user plane network element. This will be further described in conjunction with "Method 2" in Figure 7 below.
  • the first session management network element is a session management network element serving the first session in the first network slice
  • the first user plane network element is a user plane network element serving the first session in the first network slice
  • the third user plane network element is The network element is a user plane network element serving the first session in the third network slice
  • the third network slice is a network slice associated with the home network of the terminal device for the first session.
  • the mobility management network element when the terminal device moves out of the service range of the second network slice, the mobility management network element triggers the corresponding session management network element to perform the session release procedure. In this way, the session is interrupted and therefore the continuity of the session cannot be maintained.
  • the mobility management network element determines that the terminal device is in the visited network
  • the first network slice can serve the first session of the terminal device, which triggers the migration of the first session from the second network slice to the first network slice, so that the continuity of the session can be maintained.
  • another network slice selection method provided by this embodiment of the application includes the following steps:
  • the first access network device receives the single network slice selection assistance information (S-NSSAI) of the first network slice from the second access network device and the S-NSSAI of the second network slice.
  • S-NSSAI single network slice selection assistance information
  • the first network slice and the second network slice are network slices in which the first session of the terminal device is in the visited network of the terminal device and the third network slice has a mapping relationship, and the second network slice is the first session in the visited network The currently associated network slice, and the third network slice is a network slice associated with the home network of the terminal device for the first session.
  • the first access network device determines that the second network slice is not supported, but supports the first network slice.
  • the first access network device sends first indication information to the mobility management network element, where the first indication information is used to indicate that the first network slice can serve the first session.
  • the mobility management network element when the terminal device moves out of the service range of the second network slice, the mobility management network element triggers the corresponding session management network element to perform the session release procedure, so that the session is interrupted, and therefore the continuity of the session cannot be maintained.
  • the method for network slice selection provided by the embodiments of the present application, for the first session of the established terminal device, when the terminal device moves out of the service range of the second network slice, if the first access network device determines to support the first network slice, The first indication information used to indicate that the first network slice can serve the first session is sent to the mobility management network element, and then the mobility management network element triggers the migration of the first session from the second network slice to the first network slice, so that Maintain the continuity of the conversation.
  • the application in the mobility registration update process includes the following steps:
  • a terminal device in an idle state initiates a mobility registration update process, and sends a message a to the AMF network element through the first RAN device.
  • the AMF network element receives the message a from the terminal device.
  • message a carries the globally unique temporary UE identity (5G-GUTI) and requested NSSAI (requested NSSAI) and other parameters.
  • the first RAN device can address the AMF network element according to 5G-GUTI. To repeat.
  • the AMF network element in the embodiment of the present application is located in the visited network of the terminal device, which is described here in a unified manner, and will not be repeated in the following.
  • the message a in the embodiment of the present application may be, for example, a mobility registration request (registration request) message or a periodic registration update request message as shown in FIG. 7, which is not limited in the present invention.
  • the AMF network element determines that the terminal device has moved out of the service range of the second network slice, and the terminal device is currently located in the service range of the first network slice.
  • the first network slice and the third network slice have a mapping relationship
  • the third network slice is a network slice associated with the first session of the terminal device in the home network of the terminal device.
  • the AMF network element may learn that the terminal device has established the first session according to the stored context of the terminal device. If the first session is a home-routed session, the AMF network element further determines the visited network S-NSSAI (visited PLMN S-NSSAI, VS-NSSAI) corresponding to the first session and the home network S- NSSAI (home PLMN S-NSSAI, HS-NSSAI). At the same time, the AMF network element determines that the terminal device has moved out of the VS-NSSAI according to the current location information of the terminal device (such as the tracking area identity (TAI)). 2. The service scope of network slicing. Further, the AMF network element can determine whether there is a mapping relationship between other network slices and the third network slice indicated by the H-S-NSSAI at the current location of the terminal device.
  • TAI tracking area identity
  • the AMF network element can determine whether there is a mapping relationship between other network slices and the third network slice indicated by HS-NSSAI at the current location of the terminal device. For example, the AMF network element is based on the stored VPLMN and HPLMN. The roaming protocol determines whether there is a specific mapping relationship between other network slices and the third network slice at the current location of the terminal device.
  • the terminal device is currently located within the service range of the first network slice, and the roaming agreement includes the mapping relationship between the S-NSSAI of the third network slice (ie HS-NSSAI) and the S-NSSAI of the first network slice, then the AMF network
  • the element can determine that the current location of the terminal device has a mapping relationship between the first network slice and the third network slice indicated by the HS-NSSAI.
  • the AMF network element can determine whether there is a mapping relationship between other network slices and the third network slice indicated by HS-NSSAI at the current location of the terminal device, for example: the AMF network element sends a query to the NSSF network element
  • the query message carries the home PLMN ID (HPLMN ID) of the terminal device, the current location information of the terminal device, and the NSSAI (HS-NSSAI) of the third network slice, which is used to request that the current location of the terminal device can be mapped to The information of the network slice of the visited network of the terminal device of the third network slice; further, the AMF network element receives the allowed NSSAI (allowed NSSAI) from the terminal device of the NSSF network element in the visited network, as well as the allowed NSSAI and the third network
  • the mapping of the sliced NSSAI mapping of allowed NSSAI
  • the AMF network element since the AMF network element determines that the current location of the terminal device has a mapping relationship between the first network slice and the third network slice indicated by HS-NSSAI, the AMF network element can determine to reserve the first session, However, the VS-NSSAI corresponding to the first session is updated, that is, the AMF network element triggers the migration of the first session from the second network slice to the first network slice. Two implementation manners in which the AMF network element triggers the migration of the first session from the second network slice to the first network slice are given below.
  • AMF triggers the first V-SMF network element to rebuild the N9 tunnel of the first session (such as the N9 tunnel between the first V-UPF network element and the H-UPF network element), but because the terminal The device is in an idle state, so in the mobility registration update process, the N3 tunnel of the first session does not need to be established (such as the N3 tunnel between the first V-UPF network element and the first RAN device), where the first V-SMF
  • the network element is selected by the AMF network element according to the S-NSSAI of the first network slice.
  • the network slice selection method provided by the embodiment of the present application further includes the following steps S703a-S708a:
  • the AMF network element sends a message b to the first V-SMF network element.
  • the first V-SMF network element receives the message b from the AMF network element.
  • the message b is used to request the establishment of user plane resources between the first V-UPF network element and the H-UPF network element.
  • the message b in the embodiment of the present application may carry the session identifier of the first session, the S-NSSAI of the first network slice, the identifier of the H-SMF network element, and the H-S-NSSAI.
  • the session identifier of the first session is the identifier of the first session previously established by the terminal device determined by the AMF network element according to the context of the terminal device, the identifier of the H-SMF network element is used to identify the H-SMF network element, and the HS-NSSAI is
  • the first session is the S-NSSAI associated with the HPLMN of the terminal device, that is, the S-NSSAI of the third network slice.
  • the message b may also carry indication information a, which is used to indicate that the first V-SMF network element only establishes the N9 tunnel corresponding to the first session, and the N3 tunnel does not need to be established.
  • the message b in the embodiment of the present application may be, for example, a create session management (session management, SM) context request (create SM context request) message as shown in FIG. 7.
  • the message b in the embodiment of the present application may also be a servicing call to Nsmf_PDUSession_CreateSMContext, which is not specifically limited in the embodiment of the present application.
  • the first V-SMF network element selects the first V-UPF network element according to the S-NSSAI of the first network slice, and obtains the information of the first N9 tunnel between the first V-UPF network element and the H-UPF network element The first tunnel information.
  • the first tunnel information may be allocated by the first V-SMF network element, or may be allocated by the first V-UPF network element, which is not specifically limited in the embodiment of the present application.
  • the first tunnel information can be understood as the downlink tunnel information of the first N9 tunnel corresponding to the first session, which is described here in a unified manner, and will not be described in detail below.
  • the first tunnel information may be, for example, a tunnel identifier of the first N9 tunnel on the side of the first V-UPF network element (which may be recorded as a core network tunnel identifier (CN tunnel ID)).
  • CN tunnel ID core network tunnel identifier
  • the first V-SMF network element addresses the H-SMF network element corresponding to the first session according to the H-SMF network element identifier, and sends a message c to the H-SMF network element.
  • the H-SMF network element receives the message c from the first V-SMF network element.
  • the message c carries the session identifier of the first session, the identifier of the first V-SMF network element, the first tunnel information of the HS-NSSAI and the first N9 tunnel, and is used to request the H-SMF network element to update the first session The context of the N9 tunnel.
  • the H-SMF network element after the H-SMF network element receives the message c, it can send the first tunnel information of the first N9 tunnel to the H-UPF network element, so that the subsequent H-UPF network element can send the message to the first V-
  • the UPF network element sends downlink data, which is not specifically limited in the embodiment of the present application.
  • the message c in the embodiment of the present application may be, for example, an update SM context request (update SM context request) message as shown in FIG. 7.
  • the message c in the embodiment of the present application may also call Nsmf_PDUSession_UpdateSMContext for servicing, which is not specifically limited in the embodiment of the present application.
  • the H-SMF network element sends a message d to the first V-SMF network element.
  • the first V-SMF network element receives the message d from the H-SMF network element.
  • the message d carries the second tunnel information of the first N9 tunnel between the first V-UPF network element and the H-UPF network element.
  • the second tunnel information may be allocated by the H-SMF network element, or may be allocated by the H-UPF network element, which is not specifically limited in the embodiment of the present application.
  • the second tunnel information can be understood as the uplink tunnel information of the first N9 tunnel corresponding to the first session, which is described here in a unified manner, and will not be described in detail below.
  • the second tunnel information may be, for example, the tunnel identifier of the first N9 tunnel on the H-UPF network element side.
  • the first V-SMF network element can send the second tunnel information of the first N9 tunnel to the first V-UPF network element, so as to facilitate the subsequent first V-UPF network element
  • the uplink data can be sent to the H-UPF network element, which is not specifically limited in the embodiment of the present application.
  • the message d in the embodiment of the present application may be, for example, an update SM context response (update SM context response) message as shown in FIG. 7.
  • the message d in the embodiment of the present application may also be a servicing call Nsmf_PDUSession_UpdateSMContext response, which is not specifically limited in the embodiment of the present application.
  • the first V-SMF network element sends a message e to the AMF network element.
  • the AMF network element receives the message e from the first V-SMF network element.
  • the message e in the embodiment of the present application may be, for example, a create SM context response (create SM context response) message as shown in FIG. 7.
  • the message e in the embodiment of the present application may also be a servicing call Nsmf_PDUSession_UpdateSMContext response, which is not specifically limited in the embodiment of the present application.
  • the H-SMF network element sends a message f to the second V-SMF network element.
  • the second V-SMF network element receives the message f from the H-SMF network element.
  • the message f carries the session identifier of the first session, and is used to trigger the second V-SMF network element to release the session context of the first session.
  • the message f in the embodiment of the present application may be, for example, a release SM context request (release SM context request) message as shown in FIG. 7.
  • the message f in the embodiment of the present application may also be a servicing call of Nsmf_PDUSession_ReleaseSMContext, which is not specifically limited in the embodiment of the present application.
  • the second V-SMF network element may also send a release SM context response (release SM context response) message to the H-SMF network element after releasing the session context of the first session, which is not done in the embodiment of this application.
  • release SM context response release SM context response
  • the AMF network element obtains the session context of the first session allocated by the H-SMF network element from the second V-SMF, and sends the session context of the first session allocated by the H-SMF network element to The first V-SMF network element triggers the first V-SMF network element to update the N9 tunnel of the first session with the H-SMF network element, where the first V-SMF network element is the S sliced by the AMF network element according to the first network -Selected by NSSAI.
  • the network slice selection method provided in the embodiment of the present application further includes the following steps S703b-S709b:
  • the AMF network element sends a message g to the second V-SMF network element.
  • the second V-SMF network element receives the message g from the AMF network element.
  • the message g carries the session identifier of the first session, and is used to request the session context of the first session allocated by the H-SMF network element.
  • the session context includes the third tunnel information of the H-SMF network element or the H-UPF network element being the second N9 tunnel between the second V-UPF network element and the H-UPF network element.
  • the third tunnel information can also be understood as the uplink tunnel information of the second N9 tunnel corresponding to the first session, which is described here in a unified manner, and will not be repeated in the following.
  • the third tunnel information may be, for example, the tunnel identifier of the second N9 tunnel on the H-UPF network element side.
  • the message g in the embodiment of the present application may be, for example, a context request (context request) message as shown in FIG. 7.
  • the second V-SMF network element sends a message h to the AMF network element.
  • the AMF network element receives the message h from the second V-SMF network element.
  • the message h carries the session context of the first session allocated by the H-SMF network element.
  • the message h in the embodiment of the present application may be, for example, a context response (context response) message as shown in FIG. 7.
  • the second V-SMF network element may also set a timer. After the timer expires, the second V-SMF network element may release the context of the first session locally.
  • the application embodiment does not specifically limit this.
  • the AMF network element sends a message i to the first V-SMF network element.
  • the first V-SMF network element receives the message i from the AMF network element.
  • the message i is used to request the establishment of user plane resources between the first V-UPF network element and the H-UPF network element.
  • the message i in the embodiment of the present application may carry the session identifier of the first session, the S-NSSAI of the first network slice, the identifier of the H-SMF network element, and the identifier of the first session allocated by the H-SMF network element.
  • Conversation context The session identifier of the first session is the identifier of the first session previously established by the terminal device determined by the AMF network element according to the context of the terminal device, and the identifier of the H-SMF network element is used to identify the H-SMF network element.
  • the message i in the embodiment of the present application may be, for example, a create SM context request (create SM context request) message as shown in FIG. 7.
  • the first V-SMF network element selects the first V-UPF network element according to the S-NSSAI of the first network slice, and obtains the information of the first N9 tunnel between the first V-UPF network element and the H-UPF network element. The first tunnel information.
  • the first tunnel information may be allocated by the first V-SMF network element, or may be allocated by the first V-UPF network element, which is not specifically limited in the embodiment of the present application.
  • the first tunnel information may be, for example, a tunnel identifier of the first N9 tunnel on the side of the first V-UPF network element.
  • the first V-SMF network element after the first V-SMF network element selects the first V-UPF network element, it can send the second V-UPF network element and the H-UPF network element to the first V-UPF network element.
  • the third tunnel information of the second N9 tunnel Before the session is migrated, the third tunnel information is for the second V-UPF network element to send uplink data to the H-UPF network element. Since the H-UPF network element remains unchanged after the session is migrated, the third tunnel information can be reused, that is, the second tunnel information of the first N9 tunnel between the first V-UPF network element and the H-UPF network element. In this way, the subsequent first V-UPF network element can send uplink data to the H-UPF network element, which is not specifically limited in the embodiment of the present application.
  • the first V-SMF network element addresses the H-SMF network element corresponding to the first session according to the H-SMF network element identifier, and sends a message j to the H-SMF network element.
  • the H-SMF network element receives the message j from the first V-SMF network element.
  • the message j carries the session identifier of the first session, the identifier of the first V-SMF network element, HS-NSSAI, the first tunnel information of the first N9 tunnel, and the session context of the first session allocated by the H-SMF network element , Used to request the H-SMF network element to create a context with the first V-SMF network element.
  • the message j carrying the session context of the first session allocated by the H-SMF network element is to request the H-SMF network element to update the session context of the first session stored on the H-SMF network element.
  • the H-SMF network element may store the fourth V-UPF network element in the second N9 tunnel between the H-UPF network element and the second V-UPF network element stored in the session context of the first session stored on the H-SMF network element.
  • the tunnel information is replaced with the first tunnel information of the first N9 tunnel between the first V-UPF network element and the H-UPF network element.
  • the fourth tunnel information can be understood as the downlink tunnel information of the second N9 tunnel corresponding to the first session, which is described here in a unified manner, and will not be described in detail below.
  • the fourth tunnel information may be, for example, the tunnel identifier of the second N9 tunnel on the second V-UPF network element side.
  • the H-SMF network element after the H-SMF network element receives the message j, it can send the first tunnel information of the first N9 tunnel to the H-UPF network element, so that the subsequent H-UPF network element can send the message to the first V-
  • the UPF network element sends downlink data, which is not specifically limited in the embodiment of the present application.
  • FIG. 8 it is a schematic diagram of the N9 tunnel before and after the first session migration provided in this embodiment of the present application.
  • Figure 8 (a) is a schematic diagram of the N9 tunnel before the migration of the first session
  • Figure 8 (b) is a schematic diagram of the N9 tunnel after the migration of the first session.
  • the second tunnel information and the third tunnel The information is all the tunnel information on the H-UPF network element side, so it can remain unchanged before and after the migration of the first session, that is, the second tunnel information and the third tunnel information can be the same.
  • the fourth tunnel information on the H-UPF network element side is replaced with the first tunnel information.
  • the message j in the embodiment of the present application may be, for example, an update SM context request (update SM context request) message as shown in FIG. 7.
  • the H-SMF network element sends a message k to the first V-SMF network element.
  • the first V-SMF network element receives the message k from the H-SMF network element.
  • the message k in the embodiment of the present application may be, for example, an update SM context response (update SM context response) message as shown in FIG. 7.
  • the first V-SMF network element sends a message 1 to the AMF network element.
  • the AMF network element receives the message 1 from the first V-SMF network element.
  • the message 1 in the embodiment of the present application may be, for example, a create SM context response (create SM context response) message as shown in FIG. 7.
  • the first session can be successfully migrated on the core network side.
  • the method for network slice selection provided in the embodiment of the present application further includes the following steps:
  • the AMF network element sends a message m to the terminal device.
  • the terminal device receives the message m from the AMF network element.
  • the message m carries the updated allowable NSSAI and the mapping relationship between the S-NSSAI of the first network slice and the S-NSSAI of the third network slice.
  • the updated allowable NSSAI includes the S-NSSAI of the first network slice. -NSSAI.
  • the message m in the embodiment of the present application may be, for example, a mobility registration acceptance (registration accept) message as shown in FIG. 7.
  • the AMF network element sends a message n to the first V-SMF network element.
  • the first V-SMF network element receives the message n from the AMF network element.
  • the message n carries indication information b, and the indication information b is used to instruct the first V-SMF network element to initiate a modification process of the first session to notify the terminal device that the V-S-NSSAI of the first session has changed.
  • the message n in the embodiment of the present application may be, for example, a PDU session update SM context (PDU session update SM context) message as shown in FIG. 7.
  • PDU session update SM context PDU session update SM context
  • the indication information b in the embodiment of the present application may also be referred to as the first indication information, which is described here in a unified manner, and the embodiment of the present application does not specifically limit this.
  • the first V-SMF network element initiates a session modification process according to the instruction in the message n. Specifically, the first V-SMF network element sends the message o to the AMF network element. Correspondingly, the AMF network element receives the message o from the first V-SMF network element. Among them, the message o carries an N2 SM container (N2 SM container) and a PDU session modification command (PDU session modification command).
  • N2 The SM container includes the session identifier of the first session and the S-NSSAI of the first network slice; the PDU session modification command includes the session identifier of the first session, the S-NSSAI of the first network slice, and the S-NSSAI of the third network slice.
  • NSSAI The S-NSSAI of the first network slice is the modified V-S-NSSAI corresponding to the first session, and the S-NSSAI of the third network slice is the H-S-NSSAI corresponding to the first session.
  • the message o in the embodiment of the present application may be, for example, an N1N2 message transfer (N1N2 message transfer) message as shown in FIG. 7.
  • N1N2 message transfer N1N2 message transfer
  • the AMF network element sends a message p to the first RAN device.
  • the first RAN device receives the message p from the AMF network element.
  • the message p carries an N2 SM container (N2 SM container) and a PDU session modification command (PDU session modification command).
  • the message p in the embodiment of the present application may be, for example, an N2 message (N2 message) as shown in FIG. 7.
  • the first RAN device sends a message q to the terminal device.
  • the terminal device receives the message q from the first RAN device.
  • the message q carries the above-mentioned PDU session modification command.
  • the message q in the embodiment of the present application may be, for example, a NAS message (NAS message) as shown in FIG. 7.
  • NAS message NAS message
  • the terminal device learns the S-NSSAI (ie VS-NSSAI) of the first network slice corresponding to the HS-NSSAI of the first session, so that the locally stored S-NSSAI of the second network slice corresponding to the first session can be modified It is the S-NSSAI of the first network slice that can serve the first session in the current location.
  • S-NSSAI ie VS-NSSAI
  • the AMF network element when the terminal device moves out of the service range of the second network slice, the AMF network element triggers the corresponding SMF network element (such as the second V-SMF network element in the embodiment of the present application) to perform the session release process. In this way, The session is interrupted, so the continuity of the session cannot be maintained.
  • the network slice selection method provided in the embodiments of this application, for the first session of the established terminal device, when the terminal device moves out of the service range of the second network slice, if the AMF network element determines that the terminal device is in the visited network If the first network slice can serve the first session of the terminal device, the migration of the first session from the second network slice to the first network slice is triggered, so that the continuity of the session can be maintained.
  • the actions of the AMF network element or the first V-SMF network element in the above steps S701 to S713 can be executed by the processor 401 in the communication device 400 shown in FIG.
  • the embodiment does not impose any limitation on this.
  • the first RAN device when the first session of the terminal device is in the active state and the terminal device switches from the second RAN device to the first RAN device, the first RAN device will determine whether it supports the network slice corresponding to the first session. If the network slice corresponding to the first session is not supported, the first RAN device will refuse to switch the first session from the second RAN device to the first RAN device, that is, the first session fails to switch, resulting in the failure of the first session to maintain the session. Continuity.
  • the communication system shown in FIG. 2b is applied to the 5G network shown in FIG. 3b as an example.
  • FIG. 9 a network provided by an embodiment of this application is shown in FIG.
  • the method of slice selection which is applied in the handover process, includes the following steps:
  • the first RAN device sends a message r to the AMF network element.
  • the AMF network element receives the message r from the first RAN device.
  • the message r carries the TAI corresponding to the first RAN device and the PDU session rejection list (list of PDU sessions rejected with a rejection cause) that carries the rejection reason value.
  • the rejection list includes the session identifier of the first session of the terminal device, and the reason for rejection is that the first RAN device does not support the second network slice associated with the first session in the visited network of the terminal device.
  • the message r in the embodiment of the present application may be, for example, an N2 path switch request (N2 path switch request) message as shown in FIG. 9.
  • N2 path switch request N2 path switch request
  • the AMF network element determines that the terminal device has moved out of the service range of the second network slice, and the terminal device is currently located in the service range of the first network slice.
  • the first network slice and the third network slice have a mapping relationship
  • the third network slice is a network slice associated with the first session of the terminal device in the home network of the terminal device.
  • the AMF network element may determine that the terminal device has moved out of the service range of the second network slice according to the PDU session rejection list carrying the rejection reason. Further, the AMF network element can determine whether there is a mapping relationship between other network slices and the third network slice indicated by the H-S-NSSAI at the current location of the terminal device. Among them, the AMF network element determines whether the current location of the terminal device has other network slices and
  • step S702 For the manner in which the third network slice indicated by the H-S-NSSAI has a mapping relationship, reference may be made to step S702 in the embodiment shown in FIG. 7, which will not be repeated here.
  • the AMF network element since the AMF network element determines that the current location of the terminal device has a mapping relationship between the first network slice and the third network slice indicated by HS-NSSAI, the AMF network element can determine to reserve the first session, However, the VS-NSSAI corresponding to the first session is updated, that is, the AMF network element triggers the migration of the first session from the second network slice to the first network slice. Two implementation manners in which the AMF network element triggers the migration of the first session from the second network slice to the first network slice are given below.
  • the network slice selection method provided in the embodiment of the present application further includes the following steps S903a-S908a:
  • S903a-S908a are the same as steps S703a-S708a in the embodiment shown in FIG. 7.
  • steps S703a-S708a are the same as steps S703a-S708a in the embodiment shown in FIG. 7.
  • the network slice selection method provided in the embodiment of the present application further includes the following steps S903b-S909b:
  • S903b-S909b are the same as steps S703b-S709b in the embodiment shown in FIG. 7.
  • steps S703b-S709b are the same as steps S703b-S709b in the embodiment shown in FIG. 7.
  • the first session can be successfully migrated on the core network side.
  • the method for network slice selection provided in the embodiment of the present application further includes the following steps:
  • the AMF network element sends a message s to the first RAN device.
  • the first RAN device receives the message s from the AMF network element.
  • the message s in the embodiment of the present application may be, for example, an N2 path switch response (N2 path switch response) message as shown in FIG. 9.
  • N2 path switch response N2 path switch response
  • the method for network slice selection provided by the embodiment of the present application further includes the following steps:
  • the terminal device initiates a mobility registration update process, and sends a message a'to the AMF network element through the first RAN device.
  • the AMF network element receives the message a'from the terminal device.
  • the message a' carries parameters such as 5G-GUTI, requested NSSAI (requested NSSAI), and PDU session status (PDU session status).
  • 5G-GUTI is used to address AMF network elements.
  • the PDU session state indicates the state of the session currently established by the terminal device on the terminal device side. For example, the second session is active on the terminal device side, and the third session is deactivated on the terminal device side. Status, etc.
  • the PDU session state is used to synchronize the session state between the terminal device and the core network. For details, please refer to the existing implementation manner, which is not repeated here.
  • the message a'in the embodiment of the present application may be, for example, a mobility registration request (registration request) message as shown in FIG. 9.
  • the AMF network element reserves the anchor point resources of the first session on the core network side, but the first session does not establish air interface resources and N3 tunnel resources on the target side, the AMF network element sends a message m'to the terminal device.
  • the terminal device receives the message m'from the AMF network element.
  • the message m' carries indication information c
  • the indication information c is used to instruct the terminal device to initiate a service request process associated with the first session, and the service request process is used to establish air interface resources of the first session, where the air interface resources of the first session Associated with the first network slice.
  • the indication information c may be, for example, the session identifier of the first session.
  • the message m'can also carry the PDU session status confirmed by the core network, the updated allowed NSSAI, and the mapping relationship between the S-NSSAI of the first network slice and the S-NSSAI of the third network slice.
  • the updated allowed NSSAI includes the S-NSSAI of the first network slice
  • the confirmed PDU session state indicates the state of all the sessions currently established by the terminal device on the core network side.
  • the session identifier of the first session, the S-NSSAI of the first network slice, and the S-NSSAI of the third network slice may be used for the terminal device to update the S-NSSAI associated with the first session in the visited network.
  • the indication information c in the embodiment of the present application may also be referred to as the third indication information, which is described here in a unified manner, and the embodiment of the present application does not specifically limit this.
  • the message m'in the embodiment of the present application may be, for example, a mobility registration acceptance (registration accept) message as shown in FIG. 9.
  • the terminal device initiates a service request process according to the instruction information c, so that the AMF network element establishes the N3 tunnel between the first RAN device and the first V-UPF network element and the air interface side resources of the first session, where the service request
  • the process is consistent with the service request process triggered by the terminal device in the prior art, and will not be repeated here.
  • the AMF network element may send the S-NSSAI of the first network device and the session identifier of the first session to the first RAN device, and the S-NSSAI of the first network device -The session identifier of the NSSAI and the first session is used to update the S-NSSAI corresponding to the first session in the visited network, which is not specifically limited in the embodiment of the present application.
  • the AMF network element when the terminal device moves out of the service range of the second network slice, the AMF network element triggers the corresponding SMF network element (such as the second V-SMF network element in the embodiment of the present application) to perform the session release process. In this way, The session is interrupted, so the continuity of the session cannot be maintained.
  • the network slice selection method provided in the embodiments of this application, for the first session of the terminal device that has been established, when the terminal device moves out of the service range of the second network slice, if the AMF network element determines that the terminal device is in the visited network If the first network slice can serve the first session of the terminal device, the migration of the first session from the second network slice to the first network slice is triggered, so that the continuity of the session can be maintained.
  • the actions of the AMF network element or the first V-SMF network element in the above steps S901 to S913 can be executed by the processor 401 in the communication device 400 shown in FIG. 4 calling the application program code stored in the memory 403.
  • the embodiment does not impose any limitation on this.
  • the network slice selection method is applied in the handover process, including the following steps:
  • S1001-S1010 are the same as steps S901-S910 in the embodiment shown in FIG. 9.
  • steps S901-S910 are the same as steps S901-S910 in the embodiment shown in FIG. 9.
  • the method for network slice selection provided by the embodiment of the present application further includes the following steps:
  • step S1011 is the same as step S911 in the embodiment shown in FIG. 9. For related descriptions, reference may be made to the embodiment shown in FIG. 9, which will not be repeated here.
  • the AMF network element sends a message t to the first V-SMF network element.
  • the first V-SMF network element receives the message t from the AMF network element.
  • the message t carries the session identifier of the first session, and is used to request the first V-SMF network element to establish the N3 tunnel between the first RAN device and the first V-UPF network element and the air interface side resources of the first session.
  • the air interface resource of the first session is associated with the first network slice.
  • the message t in the embodiment of the present application may be, for example, the update SM context request message 1 as shown in FIG. 10.
  • the first V-SMF network element selects the first V-UPF network element according to the S-NSSAI of the first network slice, and sends a message u to the first V-UPF network element.
  • the first V-UPF network element receives the message u from the first V-SMF network element.
  • the message u may carry fifth tunnel information of the N3 tunnel between the first RAN device and the first V-UPF network element, and the fifth tunnel information may be understood as the uplink N3 tunnel information corresponding to the first session.
  • the fifth tunnel information may be, for example, the tunnel identifier of the N3 tunnel in the first V-UPF network element.
  • the message u in the embodiment of the present application may be, for example, the N4 session modification request (N4 session modification request) message 1 as shown in FIG. 10.
  • the first V-UPF network element may also send an N4 session modification response (N4 session modification response) message 1 to the first V-SMF network element, which is not specifically limited in the embodiment of the present application.
  • N4 session modification response N4 session modification response
  • the fifth tunnel information of the N3 tunnel between the first RAN device and the first V-UPF network element in the embodiment of the present application may also be allocated by the first V-UPF network element.
  • the N4 The session modification response message 1 carries the fifth tunnel information, which is described here in a unified manner, and will not be described in detail below.
  • the first V-SMF network element sends a message v to the AMF network element.
  • the AMF network element receives the message v from the first V-SMF network element.
  • the message v carries N2 SM information.
  • the N2 SM information includes the S-NSSAI of the first network slice, the QoS file, and the fifth tunnel information of the N3 tunnel between the first RAN device and the first V-UPF network element.
  • the fifth tunnel information is used for the subsequent first RAN device to send uplink data to the first V-UPF network element through the N3 tunnel.
  • the message v in the embodiment of the present application may be, for example, the update SM context response message 1 as shown in FIG. 10.
  • the AMF network element sends a message w to the first RAN device.
  • the first RAN device receives the message w from the AMF network element.
  • the message w includes the above-mentioned N2 SM information and the registration acceptance message.
  • the registration acceptance message includes the confirmed PDU session status, the updated allowed NSSAI, and the S-NSSAI of the first network slice and the information of the third network slice.
  • the mapping relationship of S-NSSAI, wherein the updated allowed NSSAI includes the S-NSSAI of the first network slice.
  • the message w in the embodiment of the present application may be, for example, an N2 request message as shown in FIG. 10.
  • the first RAN device sends a registration acceptance message to the terminal device.
  • the terminal device receives the registration acceptance message from the first RAN device.
  • the first RAN device sends a message x to the AMF network element.
  • the AMF network element receives the message x from the first RAN device.
  • the message x carries the sixth tunnel information of the N3 tunnel between the first RAN device and the first V-UPF network element allocated by the first RAN device, and the sixth tunnel information can be understood as the downlink N3 tunnel corresponding to the first session information.
  • the sixth tunnel information may include, for example, the tunnel identifier of the N3 tunnel on the first RAN device side.
  • the message x in the embodiment of the present application may be, for example, an N2 request confirmation message as shown in FIG. 10.
  • the AMF network element sends a message y to the first V-SMF network element.
  • the first V-SMF network element receives the message y from the AMF network element.
  • the message y carries the sixth tunnel information of the N3 tunnel between the first RAN device and the first V-UPF network element.
  • the message y in the embodiment of the present application may be, for example, the update SM context request message 2 as shown in FIG. 10.
  • the first V-SMF network element sends a message z to the first V-UPF network element.
  • the first V-UPF network element receives the message z from the first V-SMF network element.
  • the message z carries the sixth tunnel information of the N3 tunnel between the first RAN device and the first V-UPF network element, and the sixth tunnel information is used for the subsequent first V-UPF network element to pass the N3 tunnel to the first
  • the RAN device sends downlink data.
  • the message z in the embodiment of the present application may be, for example, the N4 session modification request message 2 as shown in FIG. 10.
  • the first V-UPF network element may also send an N4 session modification response message 2 to the first V-SMF network element, and the first V-SMF network element may also send an update SM context response message 2 to the AMF network element.
  • This application The embodiment does not specifically limit this.
  • the AMF network element when the terminal device moves out of the service range of the second network slice, the AMF network element triggers the corresponding SMF network element (such as the second V-SMF network element in the embodiment of the present application) to perform the session release process. In this way, The session is interrupted, so the continuity of the session cannot be maintained.
  • the network slice selection method provided in the embodiments of this application, for the first session of the established terminal device, when the terminal device moves out of the service range of the second network slice, if the AMF network element determines that the terminal device is in the visited network If the first network slice can serve the first session of the terminal device, the migration of the first session from the second network slice to the first network slice is triggered, so that the continuity of the session can be maintained.
  • the actions of the AMF network element or the first V-SMF network element in the above steps S1001 to S1019 can be executed by the processor 401 in the communication device 400 shown in FIG. 4 calling the application code stored in the memory 403.
  • the embodiment does not impose any limitation on this.
  • the network slice selection method is applied in the handover process, including the following steps:
  • the terminal device initiates a session establishment process, and sends a message 1 to the AMF network element through the second RAN device.
  • the AMF network element receives the message 1 from the second RAN device.
  • message 1 carries the session identifier of the first session of the terminal device, the S-NSSAI (which can be recorded as HS-NSSAI) of the third network slice associated with the home network of the terminal device, and the first session in the terminal
  • the S-NSSAI of the second network slice currently associated with the visited network of the device can be denoted as VS-NSSAI2).
  • the second RAN device supports the second network slice.
  • the message 1 in the embodiment of the present application may be, for example, a PDU session establishment request (PDU session establishment request) message as shown in FIG. 11.
  • PDU session establishment request PDU session establishment request
  • AMF network element selects the second V-SMF network element and H-SMF network element respectively according to VS-NSSAI2 and HS-NSSAI1, and triggers the second V-SMF network element to establish a session with the H-SMF network element on the core network side
  • the second V-SMF network element sends message 2 to the AMF network element.
  • the AMF network element receives the message 2 from the second V-SMF network element.
  • message 2 carries the session identifier of the first session, N2 SM information, and N1 SM container (container).
  • N2 The SM information includes the session identifier of the first session and V-S-NSSAI2, and the N2 SM container includes a PDU session establishment accept message.
  • the message 2 in the embodiment of the present application may be, for example, an N1N2 message transfer request (N1N2 message transfer request) message as shown in FIG. 11.
  • N1N2 message transfer request N1N2 message transfer request
  • the AMF network element determines whether there are other network slices that have a mapping relationship with the third network slice indicated by the H-S-NSSAI.
  • the AMF network element determining whether there is a mapping relationship between other network slices and the third network slice indicated by HS-NSSAI may include: the AMF network element determining according to the roaming agreement of the stored VPLMN and HPLMN Whether there is a specific mapping relationship between other network slices and the third network slice in the VPLMN.
  • the terminal device is currently located in the service range of the second network slice, and the roaming agreement includes the mapping relationship between the S-NSSAI of the third network slice (ie HS-NSSAI) and the S-NSSAI of the first network slice, and the third The mapping relationship between the S-NSSAI of the network slice and the S-NSSAI of the second network slice, the AMF network element can determine that the network slice in the VPLMN that has a mapping relationship with the third network slice indicated by HS-NSSAI except for the second network slice In addition, there is the first network slice.
  • the AMF network element can determine that the network slice in the VPLMN that has a mapping relationship with the third network slice indicated by HS-NSSAI except for the second network slice.
  • the AMF network element determines whether there is a mapping relationship between other network slices and the third network slice indicated by HS-NSSAI, which may include: the AMF network element sends a query message to the NSSF network element, the query message Carrying the home PLMN ID (HPLMN ID) of the terminal device and the NSSAI (HS-NSSAI) of the third network slice, used to request the network slice of the visited network of the terminal device that can be mapped to the third network slice in the VPLMN Information; further, the AMF network element receives the S-NSSAI of the first network slice and the S-NSSAI of the second network slice from the NSSF network element, where the S-NSSAI of the first network slice and the S-NSSAI of the second network slice are respectively There is a mapping relationship with the NSSAI of the third network slice, so that the AMF network element can determine that the network slice in the VPLMN that has a mapping relationship with the third network slice indicated by HS-NSSAI has
  • the method for network slice selection provided in this embodiment of the application further includes the following steps:
  • the AMF network element sends message 3 to the second RAN device.
  • the second RAN device receives message 3 from the AMF network element.
  • the message 3 carries the S-NSSAI of the second network slice, the S-NSSAI of the first network slice, N2 SM information, and N1 SM container.
  • the second RAN device may store the S-NSSAI of the second network slice, the S-NSSAI of the first network slice, and N2 SM information.
  • the second RAN device supports the second network slice, but does not support the first network slice.
  • the embodiment of this application assumes that the AMF network element determines that there is a mapping relationship between the first network slice other than the second network slice and the third network slice indicated by HS-NSSAI as an example. Of course, there may be other than the first network slice. Network slices other than the second network slice have a mapping relationship with the third network slice indicated by the HS-NSSAI, and the processing method is similar to the embodiment of the present application, and will not be repeated here.
  • the message 3 in the embodiment of the present application may be, for example, an N2 PDU session request (N2 PDU session request) message as shown in FIG. 11.
  • N2 PDU session request N2 PDU session request
  • the second RAN device sends a message 4 to the terminal device.
  • the terminal device receives the message 4 from the second RAN device.
  • message 4 includes the N1 SM container.
  • the message 4 in the embodiment of the present application may be, for example, a NAS message as shown in FIG. 11.
  • the second RAN device sends a message 5 to the first RAN device part.
  • the first RAN device receives the message 5 from the second RAN device.
  • message 5 carries the S-NSSAI of the first network slice and the S-NSSAI of the second network slice.
  • the message 5 in the embodiment of the present application may be, for example, a handover request (handover request) message.
  • the first RAN device determines that the first RAN device does not support the second network slice and the first RAN device supports the first network slice, it is considered that the first session can be successfully handed over, and the first RAN device can send a message to the AMF network element 6.
  • the AMF network element receives the message 6 from the first RAN device.
  • the message 6 carries indication information d, and the indication information d is used to indicate that the first network slice can serve the first session.
  • the indication information 6 may be, for example, the session identifier of the first session and the S-NSSAI of the first network slice.
  • the message 6 in the embodiment of the present application may be, for example, an N2 path switching request message as shown in FIG. 11.
  • the AMF network element learns that the first network slice can serve the first session, it can trigger the migration of the first session from the second network slice to the first network slice, and establish the relationship between the first RAN device and the first V-UPF network element.
  • the AMF network element when the terminal device moves out of the service range of the second network slice, the AMF network element triggers the corresponding SMF network element (such as the second V-SMF network element in the embodiment of the present application) to perform the session release process. In this way, The session is interrupted, so the continuity of the session cannot be maintained.
  • the network slice selection method provided in the embodiments of this application, for the first session of the established terminal device, when the terminal device moves out of the service range of the second network slice, if the AMF network element determines that the terminal device is in the visited network If the first network slice can serve the first session of the terminal device, the migration of the first session from the second network slice to the first network slice is triggered, so that the continuity of the session can be maintained.
  • the actions of the AMF network element or the first V-SMF network element in the above steps S1101 to S1108 can be executed by the processor 401 in the communication device 400 shown in FIG. 4 calling the application code stored in the memory 403.
  • the embodiment does not impose any limitation on this.
  • the handover process when the terminal device is in the connected state, the handover process will be triggered as the terminal device moves. If there is an Xn interface between the source RAN device and the target RAN device to be handed over by the terminal device, the terminal device will be switched to the target side through the switching process of the Xn interface. However, in the existing Xn interface switching process, if the target RAN device does not support the network slice associated with the session of the terminal device, the session of the terminal device is rejected to be switched to the target side, so that the session cannot maintain session continuity on the target side. Affect the service experience of terminal equipment.
  • the embodiment of the application introduces the slice mapping relationship in the same PLMN: a mapping relationship between slices covered by different areas is formed to ensure that the session anchor point remains unchanged after the terminal device leaves the slice coverage area, thereby realizing services Continuity.
  • the coverage of slice X and slice Y are both limited geographic areas, that is, terminal devices can only be located within the coverage of slice X or slice Y to access the slice, and the network is also deployed There is a slice A, and the slice A has a mapping relationship with the slice X, and also has a mapping relationship with the slice Y.
  • the terminal device when the terminal device moves into the coverage of slice X or slice Y and establishes a session corresponding to slice X or slice Y, if the terminal device moves out of the coverage of slice X or slice Y, because slice A and slice X or slice Y exist For the mapping relationship, the terminal device can connect to the anchor point of the session through the access slice A to ensure the business continuity of the session.
  • RAN equipment including the following first RAN equipment and second RAN equipment
  • slice mapping information slice mapping
  • N2 setup N2 setup
  • the AMF network element delivers the slice mapping to the RAN device, which is stored locally by the RAN device.
  • the method for the AMF network element to obtain the slice mapping can be local configuration or from NSSF. Network element acquisition.
  • the first RAN device may determine a matching S-NSSAI (mapped S-NSSAI) based on the slice mapping and the S-NSSAI of the current session.
  • the method for network slice selection shown in FIG. 18 includes the following steps:
  • the AMF network element obtains a first mapping relationship list, where the first mapping relationship list includes slice mapping information of each network slice supported by the AMF network element.
  • the network slice indicated by S-NSSAI-X is the same as S-NSSAI-Z.
  • the network slice indicated by NSSAI-A has a mapping relationship
  • the network slice indicated by S-NSSAI-Y has a mapping relationship with the network slice indicated by S-NSSAI-B
  • the network slice indicated by S-NSSAI-Z has a mapping relationship with S-NSSAI-C.
  • the network slice of has a mapping relationship
  • the first mapping relationship list can be as shown in Table 1:
  • mapping relationship between the two network slices can refer to the foregoing embodiment, and details are not described herein again.
  • mapping relationship shown in Table 1 is one-to-one mapping
  • the mapping relationship of network slices may also be one-to-many mapping, that is, there may be multiple network slices and a certain one.
  • the network slice has a mapping relationship, which is not specifically limited in the embodiment of the present application.
  • the network slice that has a mapping relationship with the network slice supported by the AMF network element may be referred to as a mapped network slice for short.
  • AMF network elements can support all mapped network slices.
  • AMF network elements can support network slices indicated by S-NSSAI-A, network slices indicated by S-NSSAI-B and S-NSSAI-C indications Network slicing.
  • the AMF network element may not support any one of the mapped network slices.
  • the AMF network element may not support the network slice indicated by S-NSSAI-A, the network slice indicated by S-NSSAI-B and S-NSSAI -C indicates the network slice.
  • the AMF network element may support partially mapped network slices.
  • the AMF network element may support the network slice indicated by S-NSSAI-A, the network slice indicated by S-NSSAI-B, or the network slice indicated by S-NSSAI-C.
  • One or two of the network slices may be used. The embodiment of this application does not specifically limit whether the AMF network element supports mapped network slices.
  • the AMF network element may locally configure the first mapping relationship list.
  • acquiring the first mapping relationship list by the AMF network element includes: the AMF network element acquiring the preconfigured first mapping relationship list.
  • the first mapping relationship list is not configured locally on the AMF network element.
  • acquiring the first mapping relationship list by the AMF network element includes: the AMF network element acquiring the first mapping relationship list from the NSSF network element.
  • the AMF network element may send a slice mapping request (slice mapping request) to the NSSF network element, where the slice mapping request includes the NSSAI of the network slice supported by the AMF network element.
  • the NSSF network element may determine the first mapping relationship list according to the NSSAI of the network slice supported by the AMF network element, and send a slice mapping response (slice mapping response) to the AMF network element, where the slice mapping response includes the first mapping relationship list.
  • mapping relationship list in the embodiment of the present application may also be referred to as a mapping relationship set, which is not specifically limited in the embodiment of the present application.
  • the first RAN device sends an N2 message 1 to the AMF network element.
  • the AMF network element receives the N2 message 1 from the first RAN device.
  • the N2 message 1 includes the information of the first RAN device and the slice information list supported by the first RAN device (here, the slice information list may also be referred to as a slice information set).
  • the information of the first RAN device may include the identification of the first RAN device or the tracking area (TA) where the first RAN device is located, etc., which is not specifically described in the embodiment of this application. limited.
  • the N2 message 1 in the embodiment of the present application may be an N2 connection request (N2 connection request) message or an NG setup request (NG setup request) message, etc., which is not specifically limited in the embodiment of the present application.
  • the embodiment of the present application takes the interaction between the first RAN device and an AMF network element as an example for description.
  • the first RAN device needs to send the aforementioned N2 message 1 to the multiple AMF network elements respectively, which is not the case in this embodiment of the application. Make specific restrictions.
  • the slice information list supported by the first RAN device may be as shown in Table 2. :
  • the AMF network element sends an N2 message 2 to the first RAN device.
  • the first RAN device receives the N2 message 2 from the AMF network element.
  • the N2 message 2 includes slice mapping information of the network slice supported by the first RAN device.
  • the slice information list supported by the first RAN device includes S-NSSAI-A and S-NSSAI-C
  • the network slice indicated by S-NSSAI-A and the network slice indicated by S-NSSAI-X Network slices have a mapping relationship.
  • the network slice indicated by S-NSSAI-C and the network slice indicated by S-NSSAI-Z have a mapping relationship.
  • the slice mapping information of the network slice supported by the first RAN device may be as shown in Table 3:
  • the N2 message 2 may include the S-NSSAI of the network slice supported by the AMF network element, and the S-NSSAI of the network slice having a mapping relationship with the network slice supported by each AMF network element.
  • the first RAN device receives the slice mapping information as shown in Table 1.
  • the N2 message 2 may also include the S-NSSAI of the network slice supported by the AMF network element.
  • the N2 message 2 in the embodiment of the present application may be an N2 connection response (N2 connection response) message or an NG setup response (NG setup response) message, etc., which is not specifically limited in the embodiment of the present application.
  • the first RAN device stores slice mapping information of a network slice supported by the first RAN device.
  • the second RAN device sends an N2 message 3 to the AMF network element.
  • the AMF network element receives the N2 message 3 from the second RAN device.
  • the N2 message 3 includes the information of the second RAN device and the slice information list supported by the second RAN device (here, the slice information list may also be referred to as a slice information set).
  • the information of the second RAN device may include the identifier of the second RAN device or the TA where the first RAN device is located, etc., which is not specifically limited in the embodiment of the present application.
  • the N2 message 3 in the embodiment of the present application may be an N2 connection request (N2 connection request) message or an NG setup request (NG setup request) message, etc., which is not specifically limited in the embodiment of the present application.
  • the embodiment of the present application takes the interaction between the second RAN device and an AMF network element as an example for description.
  • the second RAN device needs to send the above N2 message 3 to multiple AMF network elements respectively, which is not the case in this embodiment of the application. Make specific restrictions.
  • the slice information list supported by the second RAN device may be as shown in Table 4 :
  • the AMF network element sends an N2 message 4 to the second RAN device.
  • the second RAN device receives the N2 message 4 from the AMF network element.
  • the N2 message 4 includes slice mapping information of the network slice supported by the second RAN device.
  • the slice information list supported by the second RAN device includes S-NSSAI-Y, S-NSSAI-X, the network slice indicated by S-NSSAI-X and the network slice indicated by S-NSSAI-A Network slices have a mapping relationship.
  • the network slice indicated by S-NSSAI-Y and the network slice indicated by S-NSSAI-B have a mapping relationship.
  • the slice mapping information of the network slice supported by the second RAN device may be as shown in Table 5:
  • the N2 message 2 may include the S-NSSAI of the network slice supported by the AMF network element, and the S-NSSAI of the network slice having a mapping relationship with the network slice supported by each AMF network element.
  • the second RAN device receives the slice mapping information as shown in Table 1.
  • the N2 message 4 may also include the S-NSSAI of the network slice supported by the AMF network element.
  • the N2 message 4 in the embodiment of the present application may be an N2 connection response (N2 connection response) message or an NG setup response (NG setup response) message, etc., which is not specifically limited in the embodiment of the present application.
  • the second RAN device stores the slice mapping information of the network slice supported by the second RAN device.
  • the first RAN device obtains the slice mapping information of the network slice supported by the first RAN device from the AMF network element
  • the second RAN device obtains the network supported by the second RAN device from the AMF network element.
  • the slice mapping information of the slice is described as an example.
  • other RAN equipment can also obtain this through the above steps S1802a-S1803a or the above steps S1802b-S1803b.
  • the slice mapping information of the network slices supported by the RAN device is not described in detail in the embodiment of the present application.
  • the terminal device can be registered on the AMF network element. Specifically, in the registration process, the terminal device may send a registration request message to the AMF network element, and the registration request message carries the requested NSSAI. After receiving the registration request message, the AMF network element determines the allowed NSSAI according to the subscription data of the terminal device and the requested NSSAI.
  • the allowed NSSAI includes at least one S-NSSAI, and at least one S-NSSAI included in the allowed NSSAI is the identifier of the network slice that the terminal device is allowed to access, and specifically may be the identifier of the network slice that the terminal device is allowed to access in the current registration area.
  • one or more sessions can be established, which is not specifically limited in the embodiment of the present application.
  • the terminal device has moved, which triggers the switching process of the Xn interface. Specifically, when the terminal device is in the connected state, the terminal device performs related measurements according to the measurement configuration message issued by the second RAN device, and sends a measurement report to the second RAN device, where the measurement report contains the target to be handed over to The information list of candidate RAN devices on the side (a list of candidate Target IDs), and the results of measurement indicators between each candidate RAN device and the terminal device.
  • the measurement indicators include the reference signal strength indication obtained by the terminal device. At least one of RSSI), reference signal receiving power (RSRP), reference signal receiving quality (RSRQ), and so on.
  • the second RAN device selects one of the multiple candidate RAN devices as the target RAN device (target RAN, T-RAN) (ie, the first RAN device described below) according to the result of the measurement index reported by the terminal device. Further, the first RAN device The second RAN device determines that there is an Xn interface with the first RAN, and then triggers an Xn based handover process, and executes the following step S1806.
  • the second RAN device sends a handover request (handover request) to the first RAN device.
  • the first RAN device receives the handover request from the second RAN device.
  • the handover request includes the S-NSSAI of the network slice associated with each session of the terminal device.
  • the handover request may also include identification information of the target cell or QoS profile (profile(s)) information corresponding to each session of the terminal device, etc., which is not specifically limited in the embodiment of the present application.
  • Session 1 of the terminal device takes Session 1 of the terminal device as an example for description.
  • the first RAN device determines that the network slice associated with session 1 of the terminal device is not supported.
  • network slice 1 the network slice associated with the session 1 of the terminal device is referred to as network slice 1, which will be described in a unified manner here, and will not be repeated in the following.
  • the identifier of the network slice 1 is included in the allowed NSSAI in step S1805.
  • the first RAN device determines that the network slice 1 is not supported, which can be understood as the first RAN device determines that the TA where the first RAN device is located does not support network slice 1, for example, the TA where the first RAN device is located does not deploy network slices 1.
  • the terminal device has moved out of the service range of the network slice 1, which is explained here in a unified manner, and will not be described in detail below.
  • the first RAN device determines network slice 2. Wherein, the first RAN device supports network slice 2, and network slice 2 and network slice 1 have a mapping relationship.
  • the first RAN device determining network slice 2 includes: the first RAN device determines network slice 2 according to the S-NSSAI of network slice 1 and the mapping information between network slice 1 and network slice 2. .
  • the mapping information between network slice 1 and network slice 2 may be stored by the first RAN device in step S1804a.
  • the first RAN device may select the network slice supported by the AMF network element as network slice 2.
  • the first RAN device does not support network slice 1, but the first RAN device supports S-NSSAI-A that has a mapping relationship with S-NSSAI-X If the indicated network slice is indicated, the first RAN device may determine that the network slice indicated by S-NSSAI-A is network slice 2, and then the first RAN device may allow session 1 to be switched to the first RAN device side.
  • the first RAN device does not support network slice 1, but the first RAN device supports S-NSSAI that has a mapping relationship with S-NSSAI-X -Network slice indicated by A and S-NSSAI-AA, and supported by the AMF network element connected to the first RAN device
  • the first RAN device may determine that the network slice indicated by S-NSSAI-A is network slice 2, and the first RAN device may allow Switch 1 session 1 to the first RAN device side.
  • the first RAN device determines that the AMF network element connected to the first RAN device supports the network slice indicated by S-NSSAI-A, and the method for not supporting the network slice indicated by S-NSSAI-AA may be: the first RAN device According to the S-NSSAI of the network slice supported by the AMF network element included in the N2 message 2 obtained in step 1802a, it is determined that the AMF network element supports the network slice indicated by S-NSSAI-A, but does not support the network slice indicated by S-NSSAI-AA.
  • the first RAN device sends an N2 path switch request (N2 path switch request) to the AMF network element.
  • N2 path switch request an N2 path switch request
  • the AMF network element receives the N2 path switching request from the first RAN device.
  • the N2 path switching request includes the location information of the terminal device and N2 SM information.
  • the N2SM information includes the identifier of session 1 and the S-NSSAI of network slice 2 that has a mapping relationship with network slice 1 associated with session 1.
  • the N2 SM information may further include first indication information, where the first indication information is used to indicate that the S-NSSAI is the identifier of the network slice 2 that has a mapping relationship with the network slice 1 associated with the session 1.
  • the AMF network element sends a session update SM context request (session update SM context request) to the SMF network element.
  • the SMF network element receives the session update SM context request from the AMF network element.
  • the session update SM context request includes the above-mentioned N2 SM information.
  • the SMF network element determines whether the S-NSSAI of the network slice 2 is the S-NSSAI supported by the contract of the terminal device.
  • the SMF network element determines according to the first indication information in the N2 SM information that the S-NSSAI contained in the N2 SM information is the identifier of the network slice 2 that has a mapping relationship with the network slice 1 associated with the session 1, further, the SMF network element determines The S-NSSAI of the network slice 2 is the mapped S-NSSAI supported by the subscription of the terminal device, and the following step S1812 is continued; otherwise, the switching process ends.
  • the SMF network element sends an N4 session modification request (N4 session modification request) to the UPF network element.
  • N4 session modification request N4 session modification request
  • the UPF network element receives the N4 session modification request from the SMF network element.
  • the UPF network element sends an N4 session modification response (N4 session modification reqsponse) to the SMF network element.
  • the SMF network element receives the N4 session modification response from the UPF network element.
  • the SMF network element sends a session update SM context response (session update SM context response) to the AMF network element.
  • the AMF network element receives the session update SM context response from the SMF network element.
  • the AMF network element sends an N2 path switch request acknowledgement (N2 path switch request ACK) to the first RAN device.
  • N2 path switch request ACK N2 path switch request acknowledgement
  • the first RAN device receives the N2 path switching request confirmation from the AMF network element.
  • steps S1807-S1815 are described by taking the switching process of one session (ie session 1) of the terminal device as an example. If the switching request in step S1806 includes the NSSAI of the network slices associated with multiple sessions of the terminal device, the switching process of each session can refer to the above steps S1807-S1815, which are described here in a unified manner, and will not be repeated in the following.
  • the terminal device After the handover, the terminal device initiates a registration update process.
  • the terminal device sends a registration request message to the AMF network element. Because the network slice identifier associated with the terminal device’s session has changed, during the registration update process, the AMF network element determines new allowed NSSAI for the terminal device and sets new The allowed NSSAI is sent to the terminal device through the registration acceptance message.
  • the new allowed NSSAI includes at least one S-NSSAI, and the at least one S-NSSAI included in the new allowed NSSAI is an identifier of a network slice that allows the terminal device to access in the registration area of the target RAN device (that is, the aforementioned first RAN device).
  • new allowed NSSAI contains the identifier of network slice 2.
  • the new allowed NSSAI can be an update to the allowed NSSAI in the previous step S1805. It can be understood that the allowed NSSAI determined by the AMF network element for the terminal device before the handover includes the identifier of the network slice 1. After the handover, the AMF network element is determined by the terminal device new allowed NSSAI contains the identifier of network slice 2 but not the identifier of network slice 1.
  • the SMF network element initiates a session modification process.
  • the SMF network element sends an N1 session management message to the terminal device.
  • the N1 session management message contains the terminal device’s session identifier and network slice 2
  • the identifier of is used to update the network slice associated with the session of the terminal device stored on the terminal device, which is described here in a unified manner, and will not be repeated in the following.
  • the terminal device's session is refused to switch to the target side, resulting in that the session cannot be in the target side.
  • the side maintains the continuity of the session, which affects the service experience of the terminal device.
  • the network slice selection method provided in the embodiments of this application, even if the first RAN device does not support network slice 1, since the first RAN device can perform slice mapping, the network associated with the session of the terminal device supported by the first RAN device is determined
  • the network slice with the mapping relationship that is, the above-mentioned network slice 2 is sliced, and the session of the terminal device is migrated from the network slice 1 to the network slice 2, so the continuity of the session can be maintained.
  • the actions of the first RAN device, the second RAN device, or the AMF network element in the above steps S1801 to S1816 may be executed by the processor 401 in the communication device 400 shown in FIG. 4 calling the application program code stored in the memory 403
  • This embodiment does not impose any limitation on this.
  • the network slice In the registration process, the AMF network element delivers the slice mapping to the second RAN device, and the second RAN device saves it locally.
  • the second RAN device may determine a matching S-NSSAI (mapped S-NSSAI) based on the slice mapping and the S-NSSAI of the current session.
  • the second RAN device may send the S-NSSAI matching the S-NSSAI of the current session to the first RAN device, so that the first RAN device can determine whether to support the S-NSSAI matching the S-NSSAI of the current session.
  • Network slice indicated by NSSAI includes the following steps:
  • the AMF network element obtains a first mapping relationship list, where the first mapping relationship list includes slice mapping information of each network slice supported by the AMF network element.
  • step S1901 For the related description of step S1901, reference may be made to step S1801 of the embodiment shown in FIG. 18, which will not be repeated here.
  • the terminal device connects to the network through the second RAN device, and sends a registration request to the AMF network element through the second RAN device.
  • the AMF network element receives the registration request from the terminal device.
  • the registration request includes NSSAI (requested NSSAI) requested by the terminal device.
  • the AMF network element determines an allowed NSSAI (allowed NSSAI).
  • the AMF network element may determine the allowed NSSAI according to the subscription data of the terminal device and the requested NSSAI. For details, please refer to the existing implementation manner, which will not be repeated here.
  • the AMF network element determines a second mapping relationship list, where the second mapping relationship list includes slice mapping information of the network slice indicated by the allowed NSSAI.
  • the network slice indicated by S-NSSAI-X has a mapping relationship with the network slice indicated by S-NSSAI-A
  • the network slice indicated by S-NSSAI-Y The network slice and the network slice indicated by S-NSSAI-B have a mapping relationship, and the second mapping relationship list may be as shown in Table 6:
  • the AMF network element may determine the second mapping relationship list according to allowed NSSAI and the first mapping relationship list obtained by the AMF network element in step S1901. Wherein, the first mapping relationship list includes the second mapping relationship list.
  • mapping relationship list in the embodiment of the present application may also be referred to as a mapping relationship set, which is not specifically limited in the embodiment of the present application.
  • the AMF network element sends an N2 message 1 to the second RAN device.
  • the second RAN device receives the N2 message 1 from the AMF network element.
  • the N2 message 1 includes the foregoing allowed NSSAI, the second mapping relationship list, and the registration acceptance (registration accept) message.
  • the second RAN device stores the second mapping relationship list.
  • the second RAN device sends a registration acceptance message to the terminal device.
  • the terminal device receives the registration acceptance message from the second RAN device.
  • S1908 The terminal device sends a session establishment request to the AMF network element.
  • the AMF network element receives the session establishment request from the terminal device.
  • the session establishment request includes the identifier of the session 1 of the terminal device, the S-NSSAI and DNN of the network slice associated with the session 1 and other parameters.
  • the S-NSSAI of the network slice associated with session 1 is included in the allowed NSSAI in step S1903.
  • network slice 1 the network slice associated with the session 1 of the terminal device is referred to as network slice 1, which will be described in a unified manner here, and will not be repeated in the following.
  • the AMF network element selects the SMF network element, and triggers the SMF network element to create a session context on the core network side.
  • SMF network element selects the SMF network element, and triggers the SMF network element to create a session context on the core network side.
  • the AMF network element sends an N2 session request (N2 session request) to the second RAN device.
  • the second RAN device receives the N2 session request from the AMF network element.
  • the N2 session request includes N2 SM information
  • N2 SM information includes the identifier of session 1 and the S-NSSAI of network slice 1 associated with session 1.
  • the second RAN device determines the S-NSSAI of the network slice that has a mapping relationship with the network slice 1.
  • the second RAN device may determine the S-NSSAI of the network slice that has a mapping relationship with the network slice 1 according to the S-NSSAI of the network slice 1 associated with the session 1 and the second mapping relationship stored in step S1906.
  • steps S1908-S1911 are described by taking the establishment process of a session (ie session 1) of the terminal device as an example.
  • the terminal device may establish multiple sessions, and the procedures for establishing each session can refer to the above steps S1908-S1911, which will not be repeated here.
  • the terminal device has moved, which triggers the switching process of the Xn interface. Specifically, when the terminal device is in the connected state, the terminal device performs related measurements according to the measurement configuration message issued by the second RAN device, and sends a measurement report to the second RAN device, where the measurement report contains the target to be handed over to A list of candidate RAN devices on the side (a list of candidate Target IDs), and the results of measurement indicators between each candidate RAN device and the terminal device.
  • the measurement indicators include RSSI, RSRP, or RSRQ obtained by the terminal device.
  • the second RAN device selects one of the multiple candidate RAN devices as the target RAN device (target RAN, T-RAN) (ie, the first RAN device described below) according to the result of the measurement index reported by the terminal device. Further, the first RAN device The second RAN device determines that there is an Xn interface with the first RAN, and then triggers an Xn based handover process, and executes the following step S1912.
  • the second RAN device sends a handover request (handover request) to the first RAN device.
  • the first RAN device receives the handover request from the second RAN device.
  • the handover request includes the S-NSSAI of the network slice associated with each session of the terminal device (for example, the S-NSSAI of network slice 1) and the S-NSSAI of the network slice that has a mapping relationship with the network slices associated with each session (for example, S-NSSAI of a network slice that has a mapping relationship with network slice 1).
  • the handover request may also include at least one of the first indication information and the second indication information, where the first indication information is used to indicate which S-NSSAI is a network slice associated with the session, and the second indication The information is used to indicate which S-NSSAIs are network slices that have a mapping relationship with the network slices associated with the session, which is not specifically limited in the embodiment of the present application.
  • the handover request may also include identification information of the target cell or QoS profile (profile(s)) information corresponding to each session of the terminal device, etc., which is not specifically limited in the embodiment of the present application.
  • Session 1 of the terminal device takes Session 1 of the terminal device as an example for description.
  • the first RAN device determines that it does not support network slice 1 associated with session 1 of the terminal device, and supports network slices that have a mapping relationship with network slice 1.
  • the first RAN device may preferentially determine whether to support the terminal device according to the first indication information.
  • Network slice 1 associated with session 1 If the first RAN device determines that the network slice 1 associated with session 1 of the terminal device is not supported, the first RAN device determines whether to support network slices that have a mapping relationship with network slice 1 according to the second indication information .
  • the first RAN device may, according to the first indication information or the second indication information, Know which S-NSSAIs are network slices associated with the session, and which S-NSSAIs are network slices that have a mapping relationship with the network slices associated with the session, and then the first RAN device can determine whether to support the network slice 1 associated with session 1 of the terminal device . If the first RAN device determines that the network slice 1 associated with the session 1 of the terminal device is not supported, the first RAN device may continue to determine whether to support the network slice that has a mapping relationship with the network slice 1.
  • the first RAN device may use all network slices sent by the second RAN device.
  • the S-NSSAI judges whether the first RAN device supports at least one of the S-NSSAIs, which is not specifically limited in the embodiment of the present application.
  • the first RAN device sends an N2 path switch request (N2 path switch request) to the AMF network element.
  • N2 path switch request an N2 path switch request
  • the AMF network element receives the N2 path switching request from the first RAN device.
  • the N2 path switching request includes the location information of the terminal device and N2 SM information.
  • the N2SM information includes the identifier of session 1 and the S-NSSAI of network slice 2 that has a mapping relationship with network slice 1 associated with session 1.
  • the N2 SM information may further include third indication information, where the third indication information is used to indicate that the S-NSSAI is the identifier of the network slice 2 that has a mapping relationship with the network slice 1 associated with the session 1.
  • the first RAN device may select the network slice supported by the AMF network element as the network slice 2.
  • the AMF network element sends a session update SM context request (session update SM context request) to the SMF network element.
  • the SMF network element receives the session update SM context request from the AMF network element.
  • the session update SM context request includes the above-mentioned N2 SM information.
  • the SMF network element determines whether the S-NSSAI of the network slice 2 is the S-NSSAI supported by the contract of the terminal device.
  • the SMF network element determines according to the third indication information in the N2 SM information that the S-NSSAI included in the N2 SM information is the identifier of the network slice 2 that has a mapping relationship with the network slice 1 associated with the session 1, further, the SMF network element determines The S-NSSAI of the network slice 2 is the mapped S-NSSAI supported by the subscription of the terminal device, and the following step S1916 is continued; otherwise, the switching process ends.
  • S1916-S1920 are the same as steps S1812-S1816 in the embodiment shown in FIG. 18.
  • steps S1812-S1816 are the same as steps S1812-S1816 in the embodiment shown in FIG. 18.
  • steps S1913-S1919 are described by taking the switching process of one session (ie session 1) of the terminal device as an example. If the handover request in step S1912 includes the NSSAI of the network slices associated with multiple sessions of the terminal device, the above steps S1913-S1919 can be referred to for the handover process of each session, which will be explained here and will not be repeated in the following.
  • the terminal device's session is refused to switch to the target side, resulting in that the session cannot be in the target side.
  • the side maintains the continuity of the session, which affects the service experience of the terminal device.
  • the first RAN device determines the network slice that has a mapping relationship with network slice 1, and will compare it with The S-NSSAI of the network slice with the mapping relationship of network slice 1 is sent to the first RAN device, so that the first RAN device triggers the slicing of the session of the terminal device from the network when the first RAN device supports the network slice with the mapping relationship with network slice 1.
  • the actions of the first RAN device, the second RAN device or the AMF network element in the above steps S1901 to S1920 may be executed by the processor 401 in the communication device 400 shown in FIG. 4 calling the application program code stored in the memory 403
  • This embodiment does not impose any limitation on this.
  • the network slice The selected method: During the session establishment process, the AMF network element delivers the slice mapping to the second RAN device, and the second RAN device saves it locally. In the subsequent Xn handover process, the second RAN device may send slice mapping to the first RAN device, so that the first RAN device can determine whether to support network slices that have a mapping relationship with the network slices associated with the session of the terminal device.
  • the method for network slice selection shown in FIG. 20 includes the following steps:
  • the terminal device is successfully registered to the AMF network element through the registration process.
  • S2002 The terminal device sends a session establishment request to the AMF network element.
  • the AMF network element receives the session establishment request from the terminal device.
  • the session establishment request includes the identifier of the session 1 of the terminal device, the S-NSSAI and DNN of the network slice associated with the session 1 and other parameters.
  • the S-NSSAI and DNN of the network slice associated with the session 1 include the identifier of the session 1 of the terminal device, the S-NSSAI and DNN of the network slice associated with the session 1 and other parameters.
  • network slice 1 the network slice associated with the session 1 of the terminal device is referred to as network slice 1, which will be described in a unified manner here, and will not be repeated in the following.
  • the AMF network element selects the SMF network element, and triggers the SMF network element to create a session context on the core network side.
  • S2003 the AMF network element selects the SMF network element, and triggers the SMF network element to create a session context on the core network side.
  • the AMF network element obtains the S-NSSAI of the network slice that has a mapping relationship with the network slice 1.
  • the AMF network element may obtain the first mapping relationship list in the embodiment shown in FIG. 18 in advance. At this time, the AMF network element may be based on the S-NSSAI of the network slice 1 and the first mapping relationship. List to determine the S-NSSAI of the network slice that has a mapping relationship with network slice 1.
  • the AMF network element does not obtain the first mapping relationship list in the embodiment shown in FIG. 18 in advance.
  • the AMF network element can obtain the network with the mapping relationship of the network slice 1 from the NSSF network element.
  • Sliced S-NSSAI Specifically, the AMF network element may send a slice mapping request (slice mapping request) to the NSSF network element, where the slice mapping request includes the S-NSSAI of network slice 1.
  • the NSSF network element may determine the S-NSSAI of the network slice that has a mapping relationship with the network slice 1, and send a slice mapping response to the AMF network element.
  • the slice mapping response includes a slice mapping response that has a mapping relationship with the network slice 1.
  • S-NSSAI for network slicing.
  • the AMF network element sends an N2 session request (N2 session request) to the second RAN device.
  • the second RAN device receives the N2 session request from the AMF network element.
  • the N2 session request includes N2 SM information
  • N2 SM information includes the identifier of session 1, the S-NSSAI of network slice 1 associated with session 1, and the S-NSSAI of network slice that has a mapping relationship with network slice 1.
  • the second RAN device obtains the S-NSSAI of the network slice 1 associated with session 1 and the S-NSSAI of the network slice that has a mapping relationship with the network slice 1, it can store the S-NSSAI of the network slice 1 associated with the session 1 and the S-NSSAI of the network slice 1 associated with the session 1.
  • the network slice 1 has the S-NSSAI of the network slice of the mapping relationship, which is not specifically limited in the embodiment of the present application.
  • steps S2002-S2005 are described by taking the establishment process of a session (ie session 1) of the terminal device as an example.
  • the terminal device may establish multiple sessions, and the procedures for establishing each session can refer to the above steps S2002-S2005, which will not be repeated here.
  • the terminal device has moved, which triggers the switching process of the Xn interface. Specifically, when the terminal device is in the connected state, the terminal device performs related measurements according to the measurement configuration message issued by the second RAN device, and sends a measurement report to the second RAN device, where the measurement report contains the target to be handed over to A list of candidate RAN devices on the side (a list of candidate Target IDs), and the results of measurement indicators between each candidate RAN device and the terminal device.
  • the measurement indicators include RSSI, RSRP, or RSRQ obtained by the terminal device.
  • the second RAN device selects one of the multiple candidate RAN devices as the target RAN device (target RAN, T-RAN) (ie, the first RAN device described below) according to the result of the measurement index reported by the terminal device. Further, the first RAN device The second RAN device determines that there is an Xn interface with the first RAN, and then triggers an Xn based handover process, and executes the following step S2006.
  • S2006-S2014 are the same as steps S1912-S1920 in the embodiment shown in FIG. 19.
  • steps S1912-S1920 in the embodiment shown in FIG. 19.
  • the terminal device's session is refused to switch to the target side, resulting in that the session cannot be in the target side.
  • the side maintains the continuity of the session, which affects the service experience of the terminal device.
  • S-NSSAI of a network slice with a mapping relationship for slice 1 is sent to the second RAN device, and sent by the second RAN device to the first RAN device, so that the first RAN device supports a network slice with a mapping relationship with network slice 1
  • the session of the terminal device is triggered to migrate from the network slice 1 to the network slice supported by the first RAN device that has a mapping relationship with the network slice 1 (such as the network slice 2 described above), so that the continuity of the session can be maintained.
  • the actions of the first RAN device, the second RAN device or the AMF network element in the above steps S2001 to S2014 may be executed by the processor 401 in the communication device 400 shown in FIG. 4 calling the application program code stored in the memory 403
  • This embodiment does not impose any limitation on this.
  • FIG. 21 a method for network slice selection provided by an embodiment of this application, the method includes the following steps:
  • the first access network device receives the information of the first network slice from the second access network device, where the first network slice is a network slice associated with a session of the terminal device.
  • the first access network device in the embodiment of the present application may be, for example, the first RAN device in the embodiment shown in FIG. 18, and the second access network device may be, for example, the first RAN device in the embodiment shown in FIG. The second RAN device.
  • the network slice information in the embodiment of the present application may be, for example, the S-NSSAI of the network slice.
  • the first access network device determines that the first access network device does not support the first network slicing.
  • the first access network device determines a second network slice, where the first access network device supports the second network slice, and the second network slice has a mapping relationship with the first network slice.
  • the second network slice has a mapping relationship with the first network slice, including: the first network slice and the second network slice can provide the same service type; or, the first network slice and the second network slice can provide the same service type.
  • Network slices can share network slice instances.
  • determining the second network slice by the first access network device includes: the first access network device according to the information of the first network slice, and the mapping between the second network slice and the first network slice Information, determine the second network slice.
  • the first access network device sends indication information to the session management network element, where the indication information is used to indicate that the second network slice can serve the session.
  • the indication information may be, for example, the session identifier of the terminal device and the S-NSSAI of the second network slice.
  • steps S2101-S2104 can refer to steps S1806-S1810 in the embodiment shown in FIG. 18, which will not be repeated here.
  • the method for selecting a network slice may further include: the first access network device sends information about the second network slice to the mobility management network element, and the first access network device receives information from the mobility management network element.
  • the first access network device sends information about the second network slice to the mobility management network element, and the first access network device receives information from the mobility management network element.
  • the first access network device can perform slice mapping to determine the first access network
  • the second network slice that has a mapping relationship with the first network slice supported by the device can trigger the migration of the session of the terminal device from the first network slice to the second network slice, thereby maintaining the continuity of the session.
  • the actions of the first access network device in the above steps S2101 to S2104 can be executed by the processor 401 in the communication device 400 shown in FIG. 4 calling the application program code stored in the memory 403, which is not done in this embodiment. Any restrictions.
  • a method for network slice selection provided in an embodiment of this application, the method includes the following steps:
  • the second access network device determines the information of the first network slice and the information of the second network slice, where the first network slice is a network slice associated with the session of the terminal device, and the second network slice has a mapping with the first network slice relationship.
  • the first access network device in the embodiment of the present application may be, for example, the first RAN device in the embodiment shown in FIG. 19 or FIG. 20, and the second access network device may be, for example, FIG. 19 or FIG. 20 The second RAN device in the illustrated embodiment.
  • the network slice information in the embodiment of the present application may be, for example, the S-NSSAI of the network slice.
  • the second network slice has a mapping relationship with the first network slice, including: the first network slice and the second network slice can provide the same service type; or, the first network slice and the second network slice can provide the same service type.
  • Network slices can share network slice instances.
  • the second access network device determining the information of the first network slice and the information of the second network slice includes: the second access network device receives from the mobility management network element The information of the second network slice and the information of the first network slice.
  • the second access network device determining the information of the first network slice and the information of the second network slice includes: the second access network device receives information from the mobility management network The information of the first network slice of the element; the second access network device determines the information of the second network slice according to the information of the first network slice and the mapping information between the second network slice and the first network slice.
  • the first network slice in the embodiment of the present application may be a network slice in the network slice indicated by the NSSAI allowed by the terminal device, and the method for selecting a network slice provided in the embodiment of the present application may further include: second access
  • the network equipment receives the above-mentioned mapping information from the mobility management network element.
  • the second access network device sends the first network slice information and the second network slice information to the first access network device.
  • step S2202 may refer to step S1912 in the embodiment shown in FIG. 19 or may refer to step S2006 in the embodiment shown in FIG. 20, which will not be repeated here.
  • steps S2201-S2202 can refer to steps S1910-S1912 in the embodiment shown in FIG. 19; or, in combination with specific scenarios, another possible implementation of steps S2201-S2202 Reference may be made to steps S2005-S2006 in the embodiment shown in FIG. 20, which will not be repeated here.
  • the session of the terminal device is refused to be switched to the target side, resulting in that the session cannot maintain session continuity on the target side , Affecting the business experience of terminal equipment.
  • the second access network device can send the first network to the first access network device
  • the slice information and the information of the second network slice that has a mapping relationship with the first network slice supported by the first access network device, so that the first access network device can obtain the information of the first network slice and the information of the second network slice , which can trigger the migration of the session of the terminal device from the first network slice to the second network slice, so that the continuity of the session can be maintained.
  • the actions of the second access network device in the above steps S2201 to S2202 can be executed by the processor 401 in the communication device 400 shown in FIG. 4 calling the application code stored in the memory 403, which is not done in this embodiment. Any restrictions.
  • a method for network slice selection provided in an embodiment of this application, the method includes the following steps:
  • the first access network device receives the information of the first network slice and the information of the second network slice from the second access network device, where the first network slice is the network slice associated with the session of the terminal device, and the second network The slice has a mapping relationship with the first network slice.
  • the first access network device in the embodiment of the present application may be, for example, the first RAN device in the embodiment shown in FIG. 19 or FIG. 20, and the second access network device may be, for example, FIG. 19 or FIG. 20 The second RAN device in the illustrated embodiment.
  • the network slice information in the embodiment of the present application may be, for example, the S-NSSAI of the network slice.
  • the second network slice has a mapping relationship with the first network slice, including: the first network slice and the second network slice can provide the same service type; or, the first network slice and the second network slice can provide the same service type.
  • Network slices can share network slice instances.
  • step S2301 may refer to step S1912 in the embodiment shown in FIG. 19 or may refer to step S2006 in the embodiment shown in FIG. 20, which will not be repeated here.
  • the first access network device determines that the first access network device does not support the first network slice but supports the second network slice.
  • step S2302 may refer to step S1913 in the embodiment shown in FIG. 19 or may refer to step S2007 in the embodiment shown in FIG. 20, which will not be repeated here.
  • the first access network device sends instruction information to the session management network element, where the instruction information is used to indicate that the second network slice can serve the session.
  • the indication information may be, for example, the session identifier of the terminal device and the S-NSSAI of the second network slice.
  • steps S2301-S2303 can refer to steps S1912-S1914 in the embodiment shown in FIG. 19; or, in combination with specific scenarios, another possible implementation of steps S2301-S2303 Reference may be made to steps S2006-S2008 in the embodiment shown in FIG. 20, which will not be repeated here.
  • the session of the terminal device is refused to be switched to the target side, resulting in that the session cannot maintain session continuity on the target side , Affecting the business experience of terminal equipment.
  • the network slice selection method provided in the embodiments of the present application, even if the first access network device does not support the network slice associated with the session of the terminal device, because the first access network device can obtain the information of the first network slice and the first connection
  • the information of the second network slice that has a mapping relationship with the first network slice supported by the network access device can trigger the migration of the session of the terminal device from the first network slice to the second network slice, so the continuity of the session can be maintained.
  • the actions of the first access network device in the above steps S2301 to S2303 can be executed by the processor 401 in the communication device 400 shown in FIG. 4 calling the application program code stored in the memory 403, which is not done in this embodiment. Any restrictions.
  • a method for network slice selection provided in an embodiment of this application, the method includes the following steps:
  • the mobility management network element determines the information of the first network slice and the information of the second network slice, where the second network slice has a mapping relationship with the first network slice.
  • the network slice information in the embodiment of the present application may be, for example, the S-NSSAI of the network slice.
  • the second network slice has a mapping relationship with the first network slice, including: the first network slice and the second network slice can provide the same service type; or, the first network slice and the second network slice can provide the same service type.
  • Network slices can share network slice instances.
  • the mobility management network element determines the information of the first network slice and the information of the second network slice, including: the mobility management network element determines the information of the first network slice; the mobility management network element According to the information of the first network slice and the mapping information between the second network slice and the first network slice, the information of the second network slice is determined.
  • the mobility management network element sends the mapping information of the first network slice and the second network slice to the access network device.
  • the first network slice is a network slice supported by the access network device.
  • steps S2401-S2402 can refer to steps S1802a-S1803a in the embodiment shown in FIG. 18 or steps S1802b-S1803b in the embodiment shown in FIG. 18, which will not be repeated here. Go into details.
  • the first network slice is a network slice associated with a session of the terminal device.
  • steps S2401-S2402 can refer to steps S2004-S2005 in the embodiment shown in FIG. 20, which will not be repeated here.
  • the first network slice is the network slice indicated by the NSSAI allowed by the terminal device.
  • steps S2401-S2402 can refer to steps S1903-S1905 in the embodiment shown in FIG. 19, which will not be repeated here.
  • the session of the terminal device is refused to be switched to the target side, resulting in that the session cannot maintain session continuity on the target side , Affecting the business experience of terminal equipment.
  • the network slice selection method provided in the embodiments of the present application, even if the first access network device does not support the network slice associated with the session of the terminal device, because the first access network device can obtain the information of the first network slice and the first connection
  • the information of the second network slice that has a mapping relationship with the first network slice supported by the network access device can trigger the migration of the session of the terminal device from the first network slice to the second network slice, thereby maintaining the continuity of the session.
  • the actions of the mobility management network element in the above steps S2401 to S2402 can be executed by the processor 401 in the communication device 400 shown in FIG. 4 calling the application code stored in the memory 403, and this embodiment does not do anything about this. limit.
  • the methods and/or steps implemented by the mobility management network element can also be implemented by components (such as chips or circuits) that can be used for the mobility management network element;
  • the methods and/or steps implemented by the network equipment can also be implemented by components (such as chips or circuits) that can be used in the first access network device;
  • the methods and/or steps implemented by the second access network device can also be implemented by the available Implementation of components (such as chips or circuits) in the second access network device.
  • an embodiment of the present application also provides a communication device.
  • the communication device may be the mobility management network element in the foregoing method embodiment, or a device including the foregoing mobility management network element, or may be a mobility management network element.
  • the communication device may be the first access network device in the foregoing method embodiment, or the device including the foregoing first access network device, or may be a component that can be used for the first access network device; or,
  • the communication device may be the second access network device in the foregoing method embodiment, or a device including the foregoing second access network device, or a component that can be used for the second access network device.
  • the communication device includes hardware structures and/or software modules corresponding to various functions.
  • the present application can be implemented in the form of hardware or a combination of hardware and computer software. Whether a function is executed by hardware or computer software-driven hardware depends on the specific application and design constraints of the technical solution. Professionals and technicians can use different methods for each specific application to implement the described functions, but such implementation should not be considered beyond the scope of this application.
  • FIG. 12 shows a schematic structural diagram of a mobility management network element 120.
  • the mobility management network element 120 includes a transceiver module 1201 and a processing module 1202.
  • the transceiver module 1201 may also be referred to as a transceiver unit to implement a transceiver function, for example, it may be a transceiver circuit, a transceiver, a transceiver or a communication interface.
  • the processing module 1202 is used to determine that the first network slice in the visited network of the terminal device can serve the first session of the terminal device; the processing module 1202 is also used to trigger the first session to slice from the second network through the transceiver module 1201. Migrate to the first network slice, where the second network slice is the network slice currently associated with the first session in the visited network.
  • the processing module 1202 is configured to determine that the first network slice in the visited network of the terminal device can serve the first session of the terminal device, including: determining that the terminal device has moved out of the service range of the second network slice, and The terminal device is currently located within the service range of the first network slice; where the first network slice and the third network slice have a mapping relationship, and the third network slice is a network slice associated with the first session in the home network of the terminal device.
  • the transceiver module 1201 is further configured to send first indication information to the first session management network element, where the first indication information is used to instruct the first session management network element to initiate a modification process of the first session; the transceiver module 1201 also Used to receive first information and second information from the first session management network element, where the first information includes the identifier of the first session and the S-NSSAI of the first network slice, and the second information includes the identifier of the first session, First network slice
  • the transceiver module 1201 is further configured to send first information to the first access network device; and, send second information to the terminal device, where the first information and the second The information is used to update the S-NSSAI corresponding to the visited network for the first session.
  • the processing module 1202 is configured to determine that the first network slice in the visited network of the terminal device can serve the first session of the terminal device, including: receiving the first session from the first access network device through the transceiver module 1201 Two indication information, where the second indication information is used to indicate that the first network slice supported by the first access network device can serve the first session.
  • the processing module 1202 is further configured to determine that the first session is associated with other network slices except the second network slice in the visited network, where the other network slices have a mapping relationship with the third network slice, and the other network slices
  • the slice includes the first network slice
  • the third network slice is the network slice associated with the home network of the terminal device for the first session
  • the transceiver module 1201 is also used to send the single network slice selection of other network slices to the second access network device
  • the auxiliary information S-NSSAI where the second access network device is an access network device that supports the second network slicing.
  • the transceiver module 1201 is further configured to send third indication information to the terminal device.
  • the third indication information is used to instruct the terminal device to initiate a service request process associated with the first session.
  • the service request process is used to establish an air interface for the first session. Resources, where the air interface resources are associated with the first network slice.
  • the transceiver module 1201 is further configured to send a first message to the first session management network element, where the first message is used to request the first session management network element to establish the air interface resource of the first session, where the air interface resource is the same as the first session management network element. Network slice association.
  • the transceiver module 1201 is further configured to send the S-NSSAI of the first network slice and the S-NSSAI of the third network slice corresponding to the identifier of the first session to the terminal device.
  • the network slice associated with the home network of the terminal device.
  • the processing module 1202 is configured to trigger the migration of the first session from the second network slice to the first network slice through the transceiver module 1201, and includes: is configured to send a second message to the first session management network element through the transceiver module 1201, The second message is used to request the establishment of user plane resources between the first user plane network element and the third user plane network element, where the first session management network element is the session management network serving the first session in the first network slice Element, the first user plane network element is the user plane network element serving the first session in the first network slice, the third user plane network element is the user plane network element serving the first session in the third network slice, and the third network slice The network slice associated with the home network of the terminal device for the first session.
  • the processing module 1202 is configured to trigger the migration of the first session from the second network slice to the first network slice through the transceiver module 1201, including: acquiring context information of the first session in the third network slice, and the third network
  • the slice is a network slice associated with the home network of the terminal device for the first session; a third message is sent to the first session management network element through the transceiver module 1201, and the third message includes the context information of the first session in the third network slice.
  • the three messages are used to request the establishment of user plane resources between the first user plane network element and the third user plane network element, where the first session management network element is the session management network element serving the first session in the first network slice , The first user plane network element is a user plane network element serving the first session in the first network slice, and the third user plane network element is a user plane network element serving the first session in the third network slice.
  • the processing module 1202 is configured to obtain context information of the first session in the third network slice, including: being configured to send a fourth message to the second session management network element through the transceiver module 1201, and the fourth message is used to request the second session management network element.
  • the context information of a session in the third network slice, the second session management network element is the session management network element serving the first session in the second network slice; the first session is received from the second session management network element through the transceiver module 1201 Context information of the third network slice.
  • the transceiver module 1201 is further configured to send the updated allowable NSSAI and the mapping relationship between the S-NSSAI of the first network slice and the S-NSSAI of the third network slice to the terminal device, where the updated allowable NSSAI
  • the NSSAI includes the S-NSSAI of the first network slice
  • the third network slice is the network slice associated with the first session in the home network of the terminal device.
  • the processing module 1202 is configured to determine the information of the first network slice and the information of the second network slice, where the second network slice has a mapping relationship with the first network slice.
  • the transceiver module 1201 is configured to send the mapping information of the first network slice and the second network slice to the access network device.
  • the processing module 1202 is specifically configured to: determine the information of the first network slice; and determine the information of the second network slice according to the information of the first network slice and the mapping information between the second network slice and the first network slice.
  • the first network slice is a network slice supported by the access network device; or, the first network slice is a network slice associated with the session of the terminal device; or, the first network slice is a network indicated by the NSSAI allowed by the terminal device slice.
  • the mobility management network element 120 is presented in the form of dividing various functional modules in an integrated manner.
  • the "module” here may refer to a specific ASIC, a circuit, a processor and memory that executes one or more software or firmware programs, an integrated logic circuit, and/or other devices that can provide the above-mentioned functions.
  • the mobility management network element 120 may take the form of the communication device 400 shown in FIG. 4.
  • the processor 401 in the communication device 400 shown in FIG. 4 may invoke the computer execution instructions stored in the memory 403 to enable the communication device 400 to execute the network slice selection method in the foregoing method embodiment.
  • the functions/implementation process of the transceiver module 1201 and the processing module 1202 in FIG. 12 may be implemented by the processor 401 in the communication device 400 shown in FIG. 4 calling the computer execution instructions stored in the memory 403.
  • the function/implementation process of the processing module 1202 in FIG. 12 can be implemented by the processor 401 in the communication device 400 shown in FIG. 4 calling a computer execution instruction stored in the memory 403, and the function of the transceiver module 1201 in FIG. 12
  • the implementation process can be implemented through the communication interface 404 in the communication device 400 shown in FIG. 4.
  • the mobility management network element 120 provided in this embodiment can perform the above-mentioned method of network slice selection, the technical effects that can be obtained can refer to the above-mentioned method embodiment, which will not be repeated here.
  • FIG. 13 shows a schematic structural diagram of a first access network device 130.
  • the first access network device 130 includes a transceiver module 1301 and a processing module 1302.
  • the transceiver module 1301 may also be referred to as a transceiver unit to implement a transceiver function, for example, it may be a transceiver circuit, a transceiver, a transceiver or a communication interface.
  • the transceiver module 1301 is configured to receive the S-NSSAI of the first network slice and the S-NSSAI of the second network slice from the second access network device, where the first network slice and the second network slice are the terminal device
  • the first session is a network slice that has a mapping relationship between the visited network of the terminal device and the third network slice
  • the second network slice is the network slice that the first session is currently associated with in the visited network
  • the third network slice is the network slice where the first session is currently associated.
  • the network slice associated with the home network of the terminal device is used to determine that the second network slice is not supported, and the first network slice is supported; the transceiver module 1301 is also used to send second indication information to the mobility management network element, The second indication information is used to indicate that the first network slice can serve the first session.
  • the transceiver module 1301 is configured to receive information about a first network slice from a second access network device, where the first network slice is a network slice associated with a session of the terminal device.
  • the processing module 1302 is configured to determine that the first access network device does not support the first network slicing.
  • the processing module 1302 is further configured to determine a second network slice, where the first access network device supports the second network slice, and the second network slice has a mapping relationship with the first network slice.
  • the transceiver module 1301 is further configured to send instruction information to the session management network element, where the instruction information is used to indicate that the second network slice can serve the session.
  • the processing module 1302 is configured to determine the second network slice, including: determining the second network slice according to information of the first network slice and mapping information between the second network slice and the first network slice.
  • the transceiver module 1301 is further configured to send the information of the second network slice to the mobility management network element.
  • the transceiver module 1301 is further configured to receive the mapping information between the second network slice and the first network slice from the mobility management network element.
  • the transceiver module 1301 is configured to receive information about a first network slice and information about a second network slice from a second access network device, where the first network slice is a network slice associated with the session of the terminal device, and the second network slice is connected to The first network slice has a mapping relationship.
  • the processing module 1302 is configured to determine that the first access network device does not support the first network slice but supports the second network slice.
  • the transceiver module 1301 is further configured to send indication information to the session management network element, where the indication information is used to indicate that the second network slice can serve the session.
  • the first access network device 130 is presented in the form of dividing various functional modules in an integrated manner.
  • the "module” here may refer to a specific ASIC, a circuit, a processor and memory that executes one or more software or firmware programs, an integrated logic circuit, and/or other devices that can provide the above-mentioned functions.
  • the first access network device 130 may take the form of the communication device 400 shown in FIG. 4.
  • the processor 401 in the communication device 400 shown in FIG. 4 may invoke the computer execution instructions stored in the memory 403 to enable the communication device 400 to execute the network slice selection method in the foregoing method embodiment.
  • the functions/implementation process of the transceiver module 1301 and the processing module 1302 in FIG. 13 may be implemented by the processor 401 in the communication device 400 shown in FIG. 4 calling the computer execution instructions stored in the memory 403.
  • the function/implementation process of the processing module 1302 in FIG. 13 can be implemented by the processor 401 in the communication device 400 shown in FIG. 4 calling a computer execution instruction stored in the memory 403, and the function of the transceiver module 1301 in FIG.
  • the implementation process can be implemented through the communication interface 404 in the communication device 400 shown in FIG. 4.
  • the first access network device 130 provided in this embodiment can perform the above-mentioned method of network slice selection, the technical effects that can be obtained can refer to the above-mentioned method embodiment, which will not be repeated here.
  • FIG. 25 shows a schematic structural diagram of a second access network device 250.
  • the second access network device 250 includes a transceiver module 2501 and a processing module 2502.
  • the transceiver module 2501 may also be referred to as a transceiver unit to implement a transceiver function, for example, it may be a transceiver circuit, transceiver, transceiver or communication interface.
  • the processing module 2502 is used to determine the information of the first network slice and the information of the second network slice.
  • the first network slice is the network slice associated with the session of the terminal device, and the second network slice has a mapping with the first network slice. relationship.
  • the transceiver module 2501 is configured to send the information of the first network slice and the information of the second network slice to the first access network device.
  • the processing module 2502 is specifically configured to receive the information of the second network slice and the information of the first network slice from the mobility management network element through the transceiver module 2501.
  • the processing module 2502 is specifically configured to: receive the information of the first network slice from the mobility management network element through the transceiver module 2501; according to the information of the first network slice, and the mapping between the second network slice and the first network slice Information, which determines the information of the second network slice.
  • the first network slice is a network slice in the network slice indicated by the NSSAI allowed by the terminal device; the transceiver module 2501 is further configured to receive the mapping information from the mobility management network element.
  • the second access network device 250 is presented in the form of dividing various functional modules in an integrated manner.
  • the "module” here may refer to a specific ASIC, a circuit, a processor and memory that executes one or more software or firmware programs, an integrated logic circuit, and/or other devices that can provide the above-mentioned functions.
  • the second access network device 250 may take the form of the communication device 400 shown in FIG. 4.
  • the processor 401 in the communication device 400 shown in FIG. 4 may invoke the computer execution instructions stored in the memory 403 to enable the communication device 400 to execute the network slice selection method in the foregoing method embodiment.
  • the functions/implementation process of the transceiver module 2501 and the processing module 2502 in FIG. 25 may be implemented by the processor 401 in the communication device 400 shown in FIG. 4 calling a computer execution instruction stored in the memory 403.
  • the function/implementation process of the processing module 2502 in FIG. 25 can be implemented by the processor 401 in the communication device 400 shown in FIG. 4 calling a computer execution instruction stored in the memory 403, and the function of the transceiver module 2501 in FIG. 25
  • the implementation process can be implemented through the communication interface 404 in the communication device 400 shown in FIG. 4.
  • the second access network device 250 provided in this embodiment can perform the above-mentioned method of network slice selection, the technical effects that can be obtained can refer to the above-mentioned method embodiment, which will not be repeated here.
  • one or more of the above modules or units can be implemented by software, hardware or a combination of both.
  • the software exists in the form of computer program instructions and is stored in the memory, and the processor can be used to execute the program instructions and implement the above method flow.
  • the processor can be built in SoC (system on chip) or ASIC, or it can be an independent semiconductor chip.
  • SoC system on chip
  • ASIC application specific integrated circuit
  • the processor's internal processing is used to execute software instructions to perform calculations or processing, and may further include necessary hardware accelerators, such as field programmable gate array (FPGA), PLD (programmable logic device) , Or a logic circuit that implements dedicated logic operations.
  • FPGA field programmable gate array
  • PLD programmable logic device
  • the hardware can be a CPU, a microprocessor, a digital signal processing (digital signal processing, DSP) chip, a microcontroller unit (MCU), an artificial intelligence processor, an ASIC, Any one or any combination of SoC, FPGA, PLD, dedicated digital circuit, hardware accelerator, or non-integrated discrete device can run necessary software or do not rely on software to perform the above method flow.
  • DSP digital signal processing
  • MCU microcontroller unit
  • an artificial intelligence processor an ASIC
  • Any one or any combination of SoC, FPGA, PLD, dedicated digital circuit, hardware accelerator, or non-integrated discrete device can run necessary software or do not rely on software to perform the above method flow.
  • an embodiment of the present application further provides a communication device (for example, the communication device may be a chip or a chip system), and the communication device includes a processor for implementing the method in any of the foregoing method embodiments.
  • the communication device further includes a memory.
  • the memory is used to store necessary program instructions and data, and the processor can call the program code stored in the memory to instruct the communication device to execute the method in any of the foregoing method embodiments.
  • the memory may not be in the communication device.
  • the communication device is a chip system, it may be composed of a chip, or may include a chip and other discrete devices, which is not specifically limited in the embodiment of the present application.
  • the computer may be implemented in whole or in part by software, hardware, firmware, or any combination thereof.
  • a software program it can be implemented in the form of a computer program product in whole or in part.
  • the computer program product includes one or more computer instructions.
  • the computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices.
  • the computer instructions may be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another computer-readable storage medium.
  • the computer instructions may be transmitted from a website, computer, server, or data center.
  • the computer-readable storage medium may be any available medium that can be accessed by a computer, or may include one or more data storage devices such as servers and data centers that can be integrated with the medium.
  • the usable medium may be a magnetic medium (for example, a floppy disk, a hard disk, and a magnetic tape), an optical medium (for example, a DVD), or a semiconductor medium (for example, a solid state disk (SSD)).

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Abstract

本申请实施例提供网络切片选择的方法、设备及系统，用于解决现有技术中，当终端设备移出某个网络切片的服务区域之后，若该终端设备已经建立了与该网络切片关联的PDU会话，该PDU会话无法保持会话的连续性的问题。方法包括：移动性管理网元确定终端设备的拜访地网络中的第一网络切片能够服务该终端设备的第一会话；移动性管理网元触发该第一会话从第二网络切片迁移到该第一网络切片，其中，该第二网络切片为该第一会话在该拜访地网络当前关联的网络切片。

Description

网络切片选择的方法、设备及系统
本申请要求于2019年09月23日提交国家知识产权局、申请号为201910900880.0、申请名称为“网络切片选择的方法、设备及系统”以及于2020年07月24日提交国家知识产权局、申请号为202010725203.2、申请名称为“网络切片选择的方法、设备及系统”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及通信技术领域，尤其涉及网络切片选择的方法、设备及系统。
背景技术
网络切片(network slice)是一个用于支持特定网络能力与网络特性的逻辑隔离的网络，可以包括端到端(end to end，E2E)的整个网络，也可以部分网络功能在多个网络切片中共享，是满足第三代合作伙伴项目(3rd generation partnership project，3GPP)提出的第五代(5th generation，5G)移动通信技术关于网络差异化需求的关键技术。通常，不同网络切片的网络特征并不相同，且要求网络切片之间相互隔离，互不影响。如增强实现(augmented reality，AR)或虚拟实现(virtual reality，VR)业务的网络切片要求大带宽、低时延业务；物联网(internet of things，IOT)业务的网络切片要求支持海量终端接入，但带宽小，对时延没要求。
由于网络切片在部署上具有区域性，因此当终端设备移动时，就可能会移出某个网络切片的服务区域。如果终端设备建立了与某个网络切片关联的分组数据网元(packet data unit，PDU)会话，当终端设备移出该网络切片的服务区域时，接入与移动性管理功能(access and mobility management function，AMF)网元会触发该PDU会话对应的会话管理功能(session management function，SMF)网元释放该PDU会话，进而SMF网元执行PDU会话释放流程，这将导致该PDU会话无法保持会话的连续性。
发明内容
本申请实施例提供网络切片选择的方法、设备及系统，用于解决现有技术中，当终端设备移出某个网络切片的服务区域之后，若该终端设备已经建立了与该网络切片关联的PDU会话，该PDU会话无法保持会话的连续性的问题。
为达到上述目的，本申请的实施例采用如下技术方案：
第一方面，提供了一种网络切片选择的方法，该方法包括：移动性管理网元确定终端设备的拜访地网络中的第一网络切片能够服务该终端设备的第一会话；移动性管理网元触发该第一会话从第二网络切片迁移到该第一网络切片，其中，该第二网络切片为该第一会话在该拜访地网络当前关联的网络切片。不像现有技术一样，当终端设备移出第二网络切片的服务范围，移动性管理网元触发对应的会话管理网元执行会话的释放流程。本申请实施例提供的网络切片选择的方法，对于已经建立的终端设备的第一会话，当终端设备移出第二网络切片的服务范围，若移动性管理网元确定终端设备的拜访地网络中的第一网络切片能够服务终端设备的第一会话，则触发第一会话从第二网络切片迁移到第一网络切片，从而可以保持会话的连续性。
在一种可能的设计中，移动性管理网元确定终端设备的拜访地网络中的第一网络切片能够服务该终端设备的第一会话，包括：移动性管理网元确定该终端设备移出了该第二网络切片的服务范围，且该终端设备当前位于该第一网络切片的服务范围内；其中，该第一网络切片与第三网络切片具有映射关系，该第三网络切片为该第一会话在该终端设备的归属地网络关联的网络切片。当然，上述移动性管理网元确定终端设备的拜访地网络中的第一网络切片能够服务该终端设备的第一会话的方式也可以理解为：移动性管理网元确定该终端设备移出了该第二网络切片的服务范围，且移动性管理网元确定该第一会话在该拜访地网络与除该第二网络切片之外的第一网络切片关联，本申请实施例对此不作具体限定。基于该方案，移动性管理网元可以确定终端设备的拜访地网络中的第一网络切片能够服务该终端设备的第一会话。
在一种可能的设计中，该方法还包括：移动性管理网元向该第一会话管理网元发送第一指示信息，该第一指示信息用于指示该第一会话管理网元发起该第一会话的修改流程；移动性管理网元接收来自该第一会话管理网元的第一信息和第二信息，其中，该第一信息包括该第一会话的标识和该第一网络切片的单网络切片选择辅助信息S-NSSAI，该第二信息包括该第一会话的标识、该第一网络切片的S-NSSAI和该第三网络切片的S-NSSAI；移动性管理网元向第一接入网设备发送该第一信息；以及，该移动性管理网元向该终端设备发送该第二信息，其中，该第一信息和该第二信息用于更新该第一会话在该拜访地网络对应的S-NSSAI。基于该方案，终端设备和第一接入网设备可以及时更新该第一会话在该拜访地网络对应的S-NSSAI。
在一种可能的设计中，移动性管理网元确定终端设备的拜访地网络中的第一网络切片能够服务该终端设备的第一会话，包括：移动性管理网元接收来自第一接入网设备的第二指示信息，该第二指示信息用于指示该第一接入网设备支持的该第一网络切片能够服务该第一会话。基于该方案，移动性管理网元可以确定终端设备的拜访地网络中的第一网络切片能够服务该终端设备的第一会话。
在一种可能的设计中，在该移动性管理网元接收来自第一接入网设备的第一指示信息之前，该方法还包括：移动性管理网元确定该第一会话在该拜访地网络与除该第二网络切片之外的其他网络切片关联，其中，该其他网络切片与第三网络切片具有映射关系，且该其他网络切片包括该第一网络切片，该第三网络切片为该第一会话在该终端设备的归属地网络关联的网络切片；移动性管理网元向第二接入网设备发送该其他网络切片的单网络切片选择辅助信息S-NSSAI，其中，该第二接入网设备为支持该第二网络切片的接入网设备。基于该方案，第二接入网设备可以获知该第一会话在拜访地网络关联的除第二网络切片之外的其他网络切片的信息。
在一种可能的设计中，该方法还包括：移动性管理网元向该终端设备发送第三指示信息，该第三指示信息用于指示该终端设备发起该第一会话关联的业务请求流程，该业务请求流程用于建立该第一会话的空口资源，其中，该空口资源与该第一网络切片关联。基于该方案，可以建立第一会话的空口资源。
在一种可能的设计中，该方法还包括：移动性管理网元向该第一会话管理网元发送第一消息，该第一消息用于请求该第一会话管理网元建立该第一会话的空口资源，其中，该空口资源与该第一网络切片关联。基于该方案，可以建立第一会话的空口资 源。
在一种可能的设计中，该方法还包括：移动性管理网元向该终端设备发送与该第一会话的标识对应的该第一网络切片的S-NSSAI和第三网络切片的S-NSSAI，该第三网络切片为该第一会话在该终端设备的归属地网络关联的网络切片。基于该方案，终端设备可以及时更新该第一会话在该拜访地网络对应的S-NSSAI。
在一种可能的设计中，该移动性管理网元触发该第一会话从第二网络切片迁移到该第一网络切片，包括：移动性管理网元向第一会话管理网元发送第二消息，该第二消息用于请求第一用户面网元与第三用户面网元之间的用户面资源的建立，其中，该第一会话管理网元为该第一网络切片中服务该第一会话的会话管理网元，该第一用户面网元为该第一网络切片中服务该第一会话的用户面网元，该第三用户面网元为第三网络切片中服务该第一会话的用户面网元，该第三网络切片为该第一会话在该终端设备的归属地网络关联的网络切片。基于该方案，可以建立第一用户面网元与第三用户面网元之间的用户面资源。
在一种可能的设计中，该移动性管理网元触发该第一会话从第二网络切片迁移到该第一网络切片，包括：移动性管理网元获取该第一会话在第三网络切片的上下文信息，该第三网络切片为该第一会话在该终端设备的归属地网络关联的网络切片；移动性管理网元向第一会话管理网元发送第三消息，该第三消息包括该第一会话在该第三网络切片的上下文信息，该第三消息用于请求第一用户面网元与第三用户面网元之间的用户面资源的建立，其中，该第一会话管理网元为该第一网络切片中服务该第一会话的会话管理网元，该第一用户面网元为该第一网络切片中服务该第一会话的用户面网元，该第三用户面网元为该第三网络切片中服务该第一会话的用户面网元。基于该方案，可以建立第一用户面网元与第三用户面网元之间的用户面资源。
在一种可能的设计中，该移动性管理网元获取该第一会话在第三网络切片的上下文信息，包括：移动性管理网元向第二会话管理网元发送第四消息，该第四消息用于请求该第一会话在该第三网络切片的上下文信息，该第二会话管理网元为该第二网络切片中服务该第一会话的会话管理网元；移动性管理网元接收来自该第二会话管理网元的该第一会话在该第三网络切片的上下文信息。
在一种可能的设计中，该方法还包括：移动性管理网元向该终端设备发送更新后的允许的NSSAI、以及该第一网络切片的S-NSSAI和第三网络切片的S-NSSAI的映射关系，其中，该更新后的允许的NSSAI中包括该第一网络切片的S-NSSAI，该第三网络切片为该第一会话在该终端设备的归属地网络关联的网络切片。基于该方案，终端设备可以及时更新允许的NSSAI以及获知第一会话在拜访地网络关联的除第二网络切片之外的其他网络切片的信息。
第二方面，提供了一种网络切片选择的方法，该方法包括：第一接入网设备接收来自第二接入网设备的第一网络切片的单网络切片选择辅助信息S-NSSAI和第二网络切片的S-NSSAI，其中，该第一网络切片和该第二网络切片是终端设备的第一会话在该终端设备的拜访地网络与第三网络切片具有映射关系的网络切片，且该第二网络切片为该第一会话在该拜访地网络当前关联的网络切片，该第三网络切片为该第一会话在该终端设备的归属地网络关联的网络切片；第一接入网设备确定不支持该第二网络 切片，支持该第一网络切片；第一接入网设备向移动性管理网元发送第二指示信息，该第二指示信息用于指示该第一网络切片能够服务该第一会话。不像现有技术一样，当终端设备移出第二网络切片的服务范围，移动性管理网元触发对应的会话管理网元执行会话的释放流程。本申请实施例提供的网络切片选择的方法，对于已经建立的终端设备的第一会话，当终端设备移出第二网络切片的服务范围，若第一接入网设备确定支持第一网络切片，可以向移动性管理网元发送用于指示第一网络切片能够服务第一会话的第一指示信息，进而由移动性管理网元触发第一会话从第二网络切片迁移到第一网络切片，从而可以保持会话的连续性。
第三方面，提供了一种通信装置用于实现上述各种方法。该通信装置可以为上述第一方面或者下述第十三方面中的移动性管理网元，或者包含上述移动性管理网元的装置；或者，该通信装置可以为上述第二方面或者下述第十方面或者下述第十二方面中的第一接入网设备，或者包含上述第一接入网设备的装置；或者，该通信装置可以为下述第十一方面中的第二接入网设备，或者包含上述第二接入网设备的装置。所述通信装置包括实现上述方法相应的模块、单元、或手段(means),该模块、单元、或means可以通过硬件实现，软件实现，或者通过硬件执行相应的软件实现。该硬件或软件包括一个或多个与上述功能相对应的模块或单元。
第四方面，提供了一种通信装置，包括：处理器和存储器；该存储器用于存储计算机指令，当该处理器执行该指令时，以使该通信装置执行上述任一方面所述的方法。该通信装置可以为上述第一方面或者下述第十三方面中的移动性管理网元，或者包含上述移动性管理网元的装置；或者，该通信装置可以为上述第二方面或者下述第十方面或者下述第十二方面中的第一接入网设备，或者包含上述第一接入网设备的装置；或者，该通信装置可以为下述第十一方面中的第二接入网设备，或者包含上述第二接入网设备的装置。
第五方面，提供了一种通信装置，包括：处理器；所述处理器用于与存储器耦合，并读取存储器中的指令之后，根据所述指令执行如上述任一方面所述的方法。该通信装置可以为上述第一方面或者下述第十三方面中的移动性管理网元，或者包含上述移动性管理网元的装置；或者，该通信装置可以为上述第二方面或者下述第十方面或者下述第十二方面中的第一接入网设备，或者包含上述第一接入网设备的装置；或者，该通信装置可以为下述第十一方面中的第二接入网设备，或者包含上述第二接入网设备的装置。
第六方面，提供了一种计算机可读存储介质，该计算机可读存储介质中存储有指令，当其在计算机上运行时，使得计算机可以执行上述或者下述任一方面所述的方法。
第七方面，提供了一种包含指令的计算机程序产品，当其在计算机上运行时，使得计算机可以执行上述或者下述任一方面所述的方法。
第八方面，提供了一种通信装置(例如，该通信装置可以是芯片或芯片系统)，该通信装置包括处理器，用于实现上述或者下述任一方面中所涉及的功能。在一种可能的设计中，该通信装置还包括存储器，该存储器，用于保存必要的程序指令和数据。该通信装置是芯片系统时，可以由芯片构成，也可以包含芯片和其他分立器件。
其中，第三方面至第八方面中任一种设计方式所带来的技术效果可参见上述第一 方面或第二方面或第三方面或第十方面至第十三方面中不同设计方式所带来的技术效果，此处不再赘述。
第九方面，提供了一种通信系统，该通信系统包括移动性管理网元和第一接入网设备；第一接入网设备，用于接收来自第二接入网设备的第一网络切片的单网络切片选择辅助信息S-NSSAI和第二网络切片的S-NSSAI，其中，该第一网络切片和该第二网络切片是终端设备的第一会话在该终端设备的拜访地网络与第三网络切片具有映射关系的网络切片，且该第二网络切片为该第一会话在该拜访地网络当前关联的网络切片，该第三网络切片为该第一会话在该终端设备的归属地网络关联的网络切片；第一接入网设备，还用于确定不支持该第二网络切片，支持该第一网络切片；第一接入网设备，还用于向移动性管理网元发送第二指示信息，该第二指示信息用于指示该第一网络切片能够服务该第一会话。移动性管理网元，用于接收来自第一接入网设备的第二指示信息，并触发该第一会话从第二网络切片迁移到第一网络切片。
其中，第九方面所带来的技术效果可参见上述第一方面或第二方面所带来的技术效果，此处不再赘述。
第十方面，提供了一种网络切片选择的方法，该方法包括：第一接入网设备接收来自第二接入网设备的第一网络切片的信息，其中，该第一网络切片为终端设备的会话关联的网络切片；第一接入网设备确定不支持该第一网络切片；第一接入网设备确定第二网络切片，其中，该第一接入网设备支持该第二网络切片，且该第二网络切片与该第一网络切片具有映射关系；第一接入网设备向会话管理网元发送指示信息，该指示信息用于指示该第二网络切片能够服务该会话。现有的Xn接口切换流程中，若第一接入网设备不支持终端设备的会话关联的网络切片，则拒绝终端设备的会话切换到目标侧，从而导致该会话无法在目标侧保持会话连续性，影响终端设备的业务体验。采用本申请实施例提供的网络切片选择的方法，即使第一接入网设备不支持终端设备的会话关联的网络切片，由于第一接入网设备可以执行切片映射，确定出第一接入网设备支持的与第一网络切片具有映射关系的第二网络切片，因此可以触发将终端设备的会话从第一网络切片迁移到第二网络切片，进而可以保持会话的连续性。
在一种可能的设计中，第一接入网设备确定第二网络切片，包括：第一接入网设备根据该第一网络切片的信息，以及第二网络切片与第一网络切片的映射信息，确定第二网络切片。
在一种可能的设计中，本申请实施例提供的网络切片选择的方法还可以包括：第一接入网设备向移动性管理网元发送该第二网络切片的信息；第一接入网设备接收来自移动性管理网元的第二网络切片与第一网络切片的映射信息。基于该方案，第一接入网设备可以获取第二网络切片与第一网络切片的映射信息。
第十一方面，提供了一种网络切片选择的方法，该方法包括：第二接入网设备确定第一网络切片的信息和第二网络切片的信息，其中，该第一网络切片为终端设备的会话关联的网络切片，该第二网络切片与该第一网络切片具有映射关系；第二接入网设备向第一接入网设备发送该第一网络切片的信息和该第二网络切片的信息。现有的Xn接口切换流程中，若第一接入网设备不支持终端设备的会话关联的网络切片，则拒绝终端设备的会话切换到目标侧，从而导致该会话无法在目标侧保持会话连续性，影 响终端设备的业务体验。采用本申请实施例提供的网络切片选择的方法，即使第一接入网设备不支持终端设备的会话关联的网络切片，由于第二接入网设备可以向第一接入网设备发送第一网络切片的信息和第一接入网设备支持的与第一网络切片具有映射关系的第二网络切片的信息，使得第一接入网设备可以获取第一网络切片的信息和第二网络切片的信息，进而可以触发将终端设备的会话从第一网络切片迁移到第二网络切片，因此可以保持会话的连续性。
在一种可能的设计中，第二接入网设备确定第一网络切片的信息和第二网络切片的信息，包括：第二接入网设备接收来自移动性管理网元的第二网络切片的信息和第一网络切片的信息。换言之，本方案中，可以由移动性管理网元确定第二网络切片的信息和第一网络切片的信息。
在一种可能的设计中，第二接入网设备确定第一网络切片的信息和第二网络切片的信息，包括：第二接入网设备接收来自移动性管理网元的第一网络切片的信息；第二接入网设备根据该第一网络切片的信息，以及第二网络切片与第一网络切片的映射信息，确定第二网络切片的信息。换言之，本方案中，第二接入网设备可以预先获知第二网络切片与第一网络切片的映射信息，进而第二接入网设备接收来自移动性管理网元的第一网络切片的信息之后，可以由第二接入网设备基于该映射信息确定第二网络切片的信息。
在一种可能的设计中，该第一网络切片为该终端设备允许的网络切片选择辅助信息NSSAI所指示的网络切片中的网络切片，本申请实施例提供的网络切片选择的方法还可以包括：第二接入网设备接收来自移动性管理网元的映射信息。基于该方案，第二接入网设备可以获知第二网络切片与第一网络切片的映射信息。
第十二方面，提供了一种网络切片选择的方法，该方法包括：第一接入网设备接收来自第二接入网设备的第一网络切片的信息和第二网络切片的信息，其中，该第一网络切片为终端设备的会话关联的网络切片，该第二网络切片与该第一网络切片具有映射关系；第一接入网设备确定不支持该第一网络切片，支持该第二网络切片；第一接入网设备向会话管理网元发送指示信息，该指示信息用于指示该第二网络切片能够服务该会话。现有的Xn接口切换流程中，若第一接入网设备不支持终端设备的会话关联的网络切片，则拒绝终端设备的会话切换到目标侧，从而导致该会话无法在目标侧保持会话连续性，影响终端设备的业务体验。采用本申请实施例提供的网络切片选择的方法，即使第一接入网设备不支持终端设备的会话关联的网络切片，由于第一接入网设备可以获取第一网络切片的信息和第一接入网设备支持的与第一网络切片具有映射关系的第二网络切片的信息，并且可以触发将终端设备的会话从第一网络切片迁移到第二网络切片，因此可以保持会话的连续性。
第十三方面，提供了一种网络切片选择的方法，该方法包括：移动性管理网元确定第一网络切片的信息和第二网络切片的信息，其中，该第二网络切片与该第一网络切片具有映射关系；移动性管理网元向接入网设备发送该第一网络切片与该第二网络切片的映射信息。现有的Xn接口切换流程中，若第一接入网设备不支持终端设备的会话关联的网络切片，则拒绝终端设备的会话切换到目标侧，从而导致该会话无法在目标侧保持会话连续性，影响终端设备的业务体验。采用本申请实施例提供的网络切 片选择的方法，即使第一接入网设备不支持终端设备的会话关联的网络切片，由于第一接入网设备可以获取第一网络切片的信息和第一接入网设备支持的与第一网络切片具有映射关系的第二网络切片的信息，因此可以触发将终端设备的会话从第一网络切片迁移到第二网络切片，进而可以保持会话的连续性。
在一种可能的设计中，移动性管理网元确定第一网络切片的信息和第二网络切片的信息，包括：移动性管理网元确定第一网络切片的信息；移动性管理网元根据该第一网络切片的信息，以及该第二网络切片与该第一网络切片的映射信息，确定该第二网络切片的信息。
在一种可能的设计中，该第一网络切片为该接入网设备支持的网络切片。基于该方案，接入网设备可以获取该接入网设备支持的网络切片的切片映射信息。
在一种可能的设计中，该第一网络切片为终端设备的会话关联的网络切片。基于该方案，接入网设备可以获取终端设备的会话关联的网络切片的切片映射信息。
在一种可能的设计中，该第一网络切片为终端设备允许的网络切片选择辅助信息NSSAI所指示的网络切片。基于该方案，接入网设备可以获取终端设备允许的NSSAI所指示的网络切片的切片映射信息。
结合上述第十方面至第十三方面中的任一方面，在一种可能的设计中，该第二网络切片与该第一网络切片具有映射关系，包括：该第一网络切片和该第二网络切片能够提供相同的业务类型；或者，该第一网络切片和该第二网络切片能够共享网络切片实例。
第十四方面，提供了一种通信系统，该通信系统包括第一接入网设备和第二接入网设备。其中，第二接入网设备，用于向第一接入网设备发送第一网络切片的信息，其中，第一网络切片为终端设备的会话关联的网络切片。第一接入网设备，用于接收来自第二接入网设备的第一网络切片的信息，并确定该第一接入网设备不支持第一网络切片。第一接入网设备，还用于确定第二网络切片，其中，第一接入网设备支持第二网络切片，且第二网络切片与第一网络切片具有映射关系；第一接入网设备，还用于向会话管理网元发送指示信息，该指示信息用于指示第二网络切片能够服务该会话。其中，第十四方面所带来的技术效果可参见上述第十方面所带来的技术效果，此处不再赘述。
第十五方面，提供了一种通信系统，该通信系统包括第一接入网设备和第二接入网设备。第二接入网设备，用于确定第一网络切片的信息和第二网络切片的信息，其中，第一网络切片为终端设备的会话关联的网络切片，第二网络切片与第一网络切片具有映射关系；第二接入网设备，还用于向第一接入网设备发送第一网络切片的信息和第二网络切片的信息。第一接入网设备，用于接收来自第二接入网设备的第一网络切片的信息和第二网络切片的信息，并确定第一接入网设备不支持第一网络切片，支持第二网络切片。第一接入网设备，还用于向会话管理网元发送指示信息，该指示信息用于指示第二网络切片能够服务该会话。其中，第十五方面所带来的技术效果可参见上述第十一方面或者第十二方面所带来的技术效果，此处不再赘述。
附图说明
图1为本申请实施例提供的通信系统的结构示意图一；
图2a为本申请实施例提供的通信系统的结构示意图二；
图2b为本申请实施例提供的通信系统的结构示意图三；
图3a为本申请实施例提供的一种可能的与图2a所示的通信系统对应的网络架构示意图；
图3b为本申请实施例提供的一种可能的与图2b所示的通信系统对应的网络架构示意图；
图4为本申请实施例提供的一种通信设备的结构示意图；
图5为本申请实施例提供的一种网络切片选择的方法的流程示意图；
图6为本申请实施例提供的另一种网络切片选择的方法的流程示意图；
图7为本申请实施例提供的网络切片选择的方法的交互示意图一；
图8为本申请实施例提供的第一会话迁移前后的N9隧道示意图；
图9为本申请实施例提供的网络切片选择的方法的交互示意图二；
图10为本申请实施例提供的网络切片选择的方法的交互示意图三；
图11为本申请实施例提供的网络切片选择的方法的交互示意图四；
图12为本申请实施例提供的移动性管理网元的结构示意图；
图13为本申请实施例提供的第一接入网设备的结构示意图；
图14为本申请实施例提供的通信系统的结构示意图四；
图15为本申请实施例提供的多切片共享网络实例的示意图；
图16为本申请实施例提供的一种可能的与图14所示的通信系统对应的网络架构示意图；
图17为本申请实施例提供的跨切片移动场景示意图；
图18为本申请实施例提供的网络切片选择的方法的交互示意图五；
图19为本申请实施例提供的网络切片选择的方法的交互示意图六；
图20为本申请实施例提供的网络切片选择的方法的交互示意图七；
图21为本申请实施例提供的又一种网络切片选择的方法的流程示意图；
图22为本申请实施例提供的又一种网络切片选择的方法的流程示意图；
图23为本申请实施例提供的又一种网络切片选择的方法的流程示意图；
图24为本申请实施例提供的又一种网络切片选择的方法的流程示意图；
图25为本申请实施例提供的第二接入网设备的结构示意图。
具体实施方式
下面将结合本申请实施例中的附图，对本申请实施例中的技术方案进行描述。其中，在本申请的描述中，除非另有说明，“/”表示前后关联的对象是一种“或”的关系，例如，A/B可以表示A或B；本申请中的“和/或”仅仅是一种描述关联对象的关联关系，表示可以存在三种关系，例如，A和/或B，可以表示：单独存在A，同时存在A和B，单独存在B这三种情况，其中A，B可以是单数或者复数。并且，在本申请的描述中，除非另有说明，“多个”是指两个或多于两个。“以下至少一项(个)”或其类似表达，是指的这些项中的任意组合，包括单项(个)或复数项(个)的任意组合。例如，a，b，或c中的至少一项(个)，可以表示：a，b，c，a-b，a-c，b-c，或a-b-c，其中a，b，c可以是单个，也可以是多个。另外，为了便于清楚描述本申请实施例的技术方案， 在本申请的实施例中，采用了“第一”、“第二”等字样对功能和作用基本相同的相同项或相似项进行区分。本领域技术人员可以理解“第一”、“第二”等字样并不对数量和执行次序进行限定，并且“第一”、“第二”等字样也并不限定一定不同。同时，在本申请实施例中，“示例性的”或者“例如”等词用于表示作例子、例证或说明。本申请实施例中被描述为“示例性的”或者“例如”的任何实施例或设计方案不应被解释为比其它实施例或设计方案更优选或更具优势。确切而言，使用“示例性的”或者“例如”等词旨在以具体方式呈现相关概念，便于理解。
此外，本申请实施例描述的网络架构以及业务场景是为了更加清楚的说明本申请实施例的技术方案，并不构成对于本申请实施例提供的技术方案的限定，本领域普通技术人员可知，随着网络架构的演变和新业务场景的出现，本申请实施例提供的技术方案对于类似的技术问题，同样适用。
如图1所示，为本申请实施例提供的一种通信系统10。该通信系统10应用于漫游场景下，终端设备的第一会话从第二网络切片迁移到第一网络切片的场景中。其中，第一网络切片和第二网络切片是终端设备的第一会话在终端设备的拜访地网络与第三网络切片具有映射关系的网络切片，且第二网络切片为第一会话在拜访地网络当前关联的网络切片，第三网络切片为第一会话在终端设备的归属地网络关联的网络切片。
如图1所示，该通信系统10包括移动性管理网元和第一会话管理网元。其中，移动性管理网元和第一会话管理网元位于终端设备的拜访地网络中。第一会话管理网元为第一网络切片中服务第一会话的会话管理网元。
可选的，如图1所示，该通信系统10还可以包括第二会话管理网元、第三会话管理网元、第一用户面网元、第二用户面网元、第三用户面网元、或者网络切片选择功能网元中的一个或多个。其中，第二会话管理网元、第一用户面网元、第二用户面网元和网络切片选择功能网元位于终端设备的拜访地网络中，第三会话管理网元和第三用户面网元位于终端设备的归属地网络中。第二会话管理网元为第二网络切片中服务第一会话的会话管理网元；第三会话管理网元为第三网络切片中服务第一会话的会话管理网元，第一用户面网元为第一网络切片中服务第一会话的用户面网元，第二用户面网元为第二网络切片中服务第一会话的用户面网元，第三用户面网元为第三网络切片中服务第一会话的用户面网元。
一种可能的实现方式中，第一会话发生迁移前后，与终端设备连接的接入网设备未发生改变。比如，如图2a所示，该通信系统10还可以包括第一接入网设备。其中，在第一会话发生迁移之前，终端设备通过第一接入网设备接入核心网络，第一接入网设备与第二用户面网元可以通信；在第一会话发生迁移之后，终端设备通过第一接入网设备接入核心网络，第一接入网设备与第一用户面网元可以通信。
另一种可能的实现方式中，第一会话发生迁移前后，与终端设备连接的接入网设备发生改变。比如，如图2b所示，该通信系统10还可以包括第一接入网设备和第二接入网设备。在第一会话发生迁移之前，终端设备通过第二接入网设备接入核心网络，第二接入网设备与第二用户面网元可以通信；在第一会话发生迁移之后，终端设备通过第一接入网设备接入核心网络，第一接入网设备与第一用户面网元可以通信。其中，第一接入网设备与第二接入网设备不同。
现有的Xn接口切换流程中，当终端设备移出终端设备的会话关联的网络切片的覆盖范围时，若目标接入网设备不支持终端设备的会话关联的网络切片，则拒绝终端设备的会话切换到目标侧，从而导致该会话无法在目标侧保持会话连续性，影响终端设备的业务体验。如图14所示，为本申请实施例提供的另一种通信系统140。该通信系统140应用于漫游或非漫游场景的Xn接口切换流程中，可以使得终端设备的会话从关联的网络切片成功迁移到与终端设备关联的网络切片具有映射关系的网络切片中，从而使得该会话在目标侧保持会话连续性，其中，目标接入网设备支持与终端设备关联的网络切片具有映射关系的网络切片。
本申请实施例中，假设终端设备的会话关联的网络切片为第一网络切片，与终端设备关联的网络切片具有映射关系的网络切片为第二网络切片，则第二网络切片与第一网络切片具有映射关系，包括：第一网络切片和第二网络切片能够提供相同的业务类型；或者，第一网络切片和第二网络切片能够共享网络切片实例，在此统一说明，以下不再赘述。
示例性的，以第一网络切片为切片A，第二网络切片为切片X为例，切片A与切片X具有映射关系意味着以下一种或多种：
1、切片A与切片X提供的业务类型相同，即切片A可以提供切片X提供的业务类型。具体地，比如，切片A的标识单网络切片选择辅助信息(single network slice selection assistance information，S-NSSAI)-A的组成部分切片/服务类型(Slice/Service type，SST)与切片X的标识S-NSSAI-X包含的SST是一样的，但是S-NSSAI-A的组成部分切片区分器(slice differentiator，SD)与S-NSSAI-X包含的SD是不一样的。由于SD不同但是SST相同，说明S-NSSAI-A和S-NSSAI-X不同，但是能提供相同的业务类型，则切片A可以与切片X存在映射关系。
2、切片A与切片X可以共享网络切片实例。具体地，比如，网络中存在网络切片实例(network slice instance)既可以服务切片A又可以服务切片X。当锚点网元属于切片A与切片X共享的网络切片实例时，则锚点网元既可以服务切片A又可以服务切片X。比如，如图15所示，当终端设备移入切片X的覆盖范围且建立了切片X对应的会话之后，该会话的锚点位于切片X，如果终端设备移出切片X的覆盖范围，由于切片A与切片X存在映射关系，终端设备可以通过接入切片A连接到该会话的锚点，保证该会话的业务连续性。
如图14所示，本申请实施例提供的通信系统140包括第一接入网设备和第二接入网设备，其中，第一接入网设备为终端设备的会话迁移后接入的接入网设备，也可以称之为目标接入网设备；第二接入网设备为终端设备的会话迁移前接入的接入网设备，也可以称之为源接入网设备。换言之，在终端设备的会话发生迁移之前，终端设备通过第二接入网设备接入核心网络；在终端设备的会话发生迁移之后，终端设备通过第一接入网设备接入核心网络。
可选的，如图14所示，该通信系统140还可以包括移动性管理网元、会话管理网元、用户面网元或者网络切片选择功能网元中的一个或多个。其中，终端设备、第一接入网设备、第二接入网设备、移动性管理网元、会话管理网元、用户面网元或者网络切片选择功能网元的连接方式可参考图14，在此不再赘述。
可选的，本申请实施例中的终端设备，可以是用于实现无线通信功能的设备，例如终端或者可用于终端中的芯片等，其可以部署在陆地上，包括室内或室外、手持或车载；也可以部署在水面上(如轮船等)；还可以部署在空中(例如飞机、气球和卫星上等)。其中，终端可以是5G网络或者未来演进的公共陆地移动网(public land mobile network，PLMN)中的用户设备(user equipment，UE)、接入终端、终端单元、终端站、移动站、移动台、远方站、远程终端、移动设备、无线通信设备、终端代理或终端装置等。接入终端可以是蜂窝电话、无绳电话、会话启动协议(session initiation protocol，SIP)电话、无线本地环路(wireless local loop，WLL)站、个人数字助理(personal digital assistant，PDA)、具有无线通信功能的手持设备、计算设备或连接到无线调制解调器的其它处理设备、车载设备或可穿戴设备，虚拟现实(virtual reality，VR)终端设备、增强现实(augmented reality，AR)终端设备、工业控制(industrial control)中的无线终端、无人驾驶(self driving)中的无线终端、远程医疗(remote medical)中的无线终端、智能电网(smart grid)中的无线终端、运输安全(transportation safety)中的无线终端、智慧城市(smart city)中的无线终端、智慧家庭(smart home)中的无线终端等。终端可以是移动的，也可以是固定的。
可选的，本申请实施例中的接入网(radio access network，RAN)设备(包括第一接入网设备或第二接入网设备)，是一种为终端设备提供无线通信功能的设备。接入网设备例如包括但不限于：5G中的下一代基站(gnodeB，gNB)、演进型节点B(evolved node B，eNB)、无线网络控制器(radio network controller，RNC)、节点B(node B，NB)、基站控制器(base station controller，BSC)、基站收发台(base transceiver station，BTS)、家庭基站(例如，home evolved nodeB，或home node B，HNB)、基带单元(baseBand unit，BBU)、传输点(transmitting and receiving point，TRP)、发射点(transmitting point，TP)、移动交换中心等。
可选的，本申请实施例中的移动性管理网元，主要用于移动网络中的移动性管理，如用户位置更新、用户注册网络、用户切换等。在5G通信系统中，移动性管理网元可以是接入与移动性管理功能(access and mobility management function，AMF)网元，Namf是AMF网元提供的基于服务的接口，AMF网元可以通过Namf与其他的网络功能通信，在未来通信如第六代(6th generation，6G)通信中，移动性管理网元仍可以是AMF网元，或者有其它名称，本申请实施例对此不作限定。
可选的，本申请实施例中的会话管理网元(包括第一会话管理网元或第二会话管理网元或第三会话管理网元)，主要用于移动网络中的会话管理，如会话建立、修改、释放。具体功能如为用户分配互联网协议(internet protocol，IP)地址、选择提供报文转发功能的用户面网元等。在5G系统中，会话管理网元可以是会话管理功能(session management function，SMF)网元，Nsmf是SMF提供的基于服务的接口，SMF可以通过Nsmf与其他的网络功能通信。在未来通信如6G中，会话管理网元仍可以是SMF网元，或有其它的名称，本申请实施例不做限定。
可选的，本申请实施例中的用户面网元(包括第一用户面网元或第二用户面网元或第三用户面网元)主要用于根据会话管理网元的路由规则执行用户数据包的转发。在5G通信系统中，用户管理网元可以是用户面功能(user plane function，UPF)网元， 在未来通信如6G通信中，用户管理网元仍可以是UPF网元，或者有其它名称，本申请实施例对此不作限定。
可选的，本申请实施例中的网络切片选择功能网元，用于为终端设备选择网络切片等。在5G通信系统中，网络切片选择功能网元可以是网络切片选择功能(network slice selection function，NSSF)网元，其中Nnssf是NSSF网元提供的基于服务的接口，NSSF网元可以通过Nnssf与其他的网络功能通信。在未来通信如6G通信中，网络切片选择功能网元仍可以是NSSF网元，或者有其它名称，本申请实施例对此不作限定。
以5G通信系统为例，如图3a所示，为本申请实施例适用的一种可能的与图2a所示的通信系统对应的网络架构示意图，如图3b所示，为本申请实施例适用的一种可能的与图2b所示的通信系统对应的网络架构示意图。其中，移动性管理网元所对应的网元或者实体可以为5G通信系统中的AMF网元，第一会话管理网元所对应的网元或者实体可以为5G通信系统中的第一拜访地SMF(visited SMF，V-SMF)网元，第二会话管理网元所对应的网元或者实体可以为5G通信系统中的第二V-SMF网元，第三会话管理网元所对应的网元或者实体可以为5G通信系统中的归属地SMF(home SMF，H-SMF)网元，第一用户面网元所对应的网元或者实体可以为5G通信系统中的第一拜访地UPF(visited UPF，V-UPF)网元，第二用户面网元所对应的网元或者实体可以为5G通信系统中的第二V-UPF网元，第三用户面网元所对应的网元或者实体可以为5G通信系统中的归属地UPF(home UPF，H-UPF)网元，网络切片选择功能网元所对应的网元或者实体可以为5G通信系统中的NSSF网元，第一接入网设备所对应的网元或者实体可以为5G通信系统中的第一RAN设备，第二接入网设备所对应的网元或者实体可以为5G通信系统中的第二RAN设备。
或者，以5G通信系统为例，如图16所示，为本申请实施例适用的一种可能的与图14所示的通信系统对应的网络架构示意图。其中，移动性管理网元所对应的网元或者实体可以为5G通信系统中的AMF网元，会话管理网元所对应的网元或者实体可以为5G通信系统中的SMF网元，用户面网元所对应的网元或者实体可以为5G通信系统中的UPF网元，网络切片选择功能网元所对应的网元或者实体可以为5G通信系统中的NSSF网元，第一接入网设备所对应的网元或者实体可以为5G通信系统中的第一RAN设备(也可以称之为目标RAN设备)，第二接入网设备所对应的网元或者实体可以为5G通信系统中的第二RAN设备(也可以称之为源RAN设备)。
其中，图3a或图3b或图16中的N1接口为终端设备与AMF网元之间的参考点；N2接口为RAN设备和AMF网元之间的(如第一RAN设备和AMF网元之间，或者第二RAN设备与AMF网元之间)参考点，用于非接入层(non-access stratum，NAS)消息和下一代应用协议(next generation application protocol，NGAP)消息的发送等；N3接口为RAN设备和V-UPF网元之间(如第一RAN设备和第一V-UPF网元之间，第一RAN设备和第二V-UPF网元之间，第二RAN设备和第二V-UPF网元之间)的参考点或者RAN设备与UPF网元之间(如图16中第一RAN设备和UPF网元之间，第二RAN设备和UPF网元之间)的参考点，用于传输用户面的数据等；N4接口为SMF网元和UPF网元之间(如第一V-SMF网元和第一V-UPF网元之间，或者第二V-SMF网元和第二V-UPF网元之间，或者H-SMF网元和H-UPF网元之间，或者图 16中的SMF与UPF网元之间)的参考点，用于传输例如N3连接的隧道标识信息，数据缓存指示信息，以及下行数据通知消息等信息；N9接口为UPF网元与UPF网元之间(如第一V-UPF网元和H-UPF网元之间，或者第二V-UPF网元和H-UPF网元之间)的参考点。
其中，图3a或图3b或图16所示的AMF网元、SMF网元(如第一V-SMF网元或者第二V-SMF网元或者H-SMF网元或者图16中的SMF网元)、NSSF网元等控制面网元可以采用服务化接口进行交互。比如，AMF网元对外提供的服务化接口可以为Namf；SMF网元对外提供的服务化接口可以为Nsmf；PCF网元对外提供的服务化接口可以为Npcf；NSSF网元对外提供的服务化接口可以为Nnssf。此外，图3a或图3b中的拜访地安全边缘保护代理(visited security edge protection proxy，vSEPP)用于终端设备的拜访地公共陆地移动网(visited public land mobile network，VPLMN)内部控制面接口的信息过滤和策略控制，以及拓扑隐藏等；图3a或图3b中的归属地安全边缘保护代理(home security edge protection proxy，hSEPP)用于终端设备的归属公共陆地移动网(home public land mobile network，HPLMN)内部控制面接口的信息过滤和策略控制，以及拓扑隐藏等；vSEPP与hSEPP通过N32接口(简称N32)连接。
需要说明的是，上述的H-SMF网元也可以称之为锚点SMF网元，上述的H-UPF网元也可以称之为锚点UPF网元，上述的第一V-UPF网元也可以称之为新(new)
V-UPF网元，上述的第二V-UPF网元也可以称之为旧(old)V-UPF网元，上述的第一V-SMF网元也可以称之为new V-SMF网元，上述的第二V-SMF网元也可以称之为old V-SMF网元，本申请实施例对此不做具体限定。
可选的，本申请实施例中的移动性管理网元、会话管理网元、第一接入网设备、第二接入网设备、第一会话管理网元、第二会话管理网元、第三会话管理网元、第一用户面网元、第二用户面网元、第三用户面网元、或者网络切片选择功能网元也可以称之为通信装置，其可以是一个通用设备或者是一个专用设备，本申请实施例对此不作具体限定。
可选的，本申请实施例中的移动性管理网元、会话管理网元、第一接入网设备、第二接入网设备、第一会话管理网元、第二会话管理网元、第三会话管理网元、第一用户面网元、第二用户面网元、第三用户面网元、或者网络切片选择功能网元的相关功能可以由一个设备实现，也可以由多个设备共同实现，还可以是由一个设备内的一个或多个功能模块实现，本申请实施例对此不作具体限定。可以理解的是，上述功能既可以是硬件设备中的网络元件，也可以是在专用硬件上运行的软件功能，或者是硬件与软件的结合，或者是平台(例如，云平台)上实例化的虚拟化功能。
例如，本申请实施例中的移动性管理网元、会话管理网元、第一接入网设备、第二接入网设备、第一会话管理网元、第二会话管理网元、第三会话管理网元、第一用户面网元、第二用户面网元、第三用户面网元、或者网络切片选择功能网元的相关功能可以通过图4中的通信设备400来实现。图4所示为本申请实施例提供的通信设备400的结构示意图。该通信设备400包括一个或多个处理器401，通信线路402，以及至少一个通信接口(图4中仅是示例性的以包括通信接口404，以及一个处理器401为例进行说明)，可选的还可以包括存储器403。
处理器401可以是一个通用中央处理器(central processing unit，CPU)，微处理器，特定应用集成电路(application-specific integrated circuit，ASIC)，或一个或多个用于控制本申请方案程序执行的集成电路。
通信线路402可包括一通路，用于连接不同组件之间。
通信接口404，可以是收发模块用于与其他设备或通信网络通信，如以太网，RAN，无线局域网(wireless local area networks，WLAN)等。例如，所述收发模块可以是收发器、收发机一类的装置。可选的，所述通信接口404也可以是位于处理器401内的收发电路，用以实现处理器的信号输入和信号输出。
存储器403可以是具有存储功能的装置。例如可以是只读存储器(read-only memory，ROM)或可存储静态信息和指令的其他类型的静态存储设备，随机存取存储器(random access memory，RAM)或者可存储信息和指令的其他类型的动态存储设备，也可以是电可擦可编程只读存储器(electrically erasable programmable read-only memory，EEPROM)、只读光盘(compact disc read-only memory，CD-ROM)或其他光盘存储、光碟存储(包括压缩光碟、激光碟、光碟、数字通用光碟、蓝光光碟等)、磁盘存储介质或者其他磁存储设备、或者能够用于携带或存储具有指令或数据结构形式的期望的程序代码并能够由计算机存取的任何其他介质，但不限于此。存储器可以是独立存在，通过通信线路402与处理器相连接。存储器也可以和处理器集成在一起。
其中，存储器403用于存储执行本申请方案的计算机执行指令，并由处理器401来控制执行。处理器401用于执行存储器403中存储的计算机执行指令，从而实现本申请实施例中提供的网络切片选择的方法。
或者，可选的，本申请实施例中，也可以是处理器401执行本申请下述实施例提供的网络切片选择的方法中的处理相关的功能，通信接口404负责与其他设备或通信网络通信，本申请实施例对此不作具体限定。
可选的，本申请实施例中的计算机执行指令也可以称之为应用程序代码，本申请实施例对此不作具体限定。
在具体实现中，作为一种实施例，处理器401可以包括一个或多个CPU，例如图4中的CPU0和CPU1。
在具体实现中，作为一种实施例，通信设备400可以包括多个处理器，例如图4中的处理器401和处理器408。这些处理器中的每一个可以是一个单核(single-core)处理器，也可以是一个多核(multi-core)处理器。这里的处理器可以包括但不限于以下至少一种：中央处理单元(central processing unit，CPU)、微处理器、数字信号处理器(DSP)、微控制器(microcontroller unit，MCU)、或人工智能处理器等各类运行软件的计算设备，每种计算设备可包括一个或多个用于执行软件指令以进行运算或处理的核。
在具体实现中，作为一种实施例，通信设备400还可以包括输出设备405和输入设备406。输出设备405和处理器401通信，可以以多种方式来显示信息。例如，输出设备405可以是液晶显示器(liquid crystal display，LCD)，发光二级管(light emitting diode，LED)显示设备，阴极射线管(cathode ray tube，CRT)显示设备，或投影仪(projector)等。输入设备406和处理器401通信，可以以多种方式接收用户的输入。 例如，输入设备406可以是鼠标、键盘、触摸屏设备或传感设备等。
上述的通信设备400有时也可以称为通信装置，其可以是一个通用设备或者是一个专用设备。例如通信设备400可以是台式机、便携式电脑、网络服务器、掌上电脑(personal digital assistant，PDA)、移动手机、平板电脑、无线终端设备、嵌入式设备、上述终端设备，上述网络设备、或具有图4中类似结构的设备。本申请实施例不限定通信设备400的类型。
如图5所示，为本申请实施例提供的一种网络切片选择的方法，该方法包括如下步骤：
S501、移动性管理网元确定终端设备的拜访地网络中的第一网络切片能够服务终端设备的第一会话。
一种可能的实现方式中，移动性管理网元确定终端设备的拜访地网络中的第一网络切片能够服务终端设备的第一会话，包括：移动性管理网元确定终端设备移出了第二网络切片的服务范围，且终端设备当前位于第一网络切片的服务范围内。换句话说，移动性管理网元确定终端设备的第一会话在拜访地网络与第一网络切片关联。其中，第一网络切片与第三网络切片具有映射关系，第三网络切片为第一会话在终端设备的归属地网络关联的网络切片。这将结合后面的图7、图9和图10进一步描述。
另一种可能的实现方式中，移动性管理网元确定终端设备的拜访地网络中的第一网络切片能够服务终端设备的第一会话，包括：移动性管理网元接收来自第一接入网设备的第一指示信息，第一指示信息用于指示第一接入网设备支持的第一网络切片能够服务第一会话。这将结合后面的图11进一步描述。
S502、移动性管理网元触发第一会话从第二网络切片迁移到第一网络切片，其中，第二网络切片为第一会话在拜访地网络当前关联的网络切片。
一种可能的实现方式中，移动性管理网元触发第一会话从第二网络切片迁移到第一网络切片，包括：移动性管理网元向第一会话管理网元发送第一消息，第一消息用于请求第一用户面网元与第三用户面网元之间的用户面资源的建立。这将结合后面的图7中的“方式一”进一步描述。
另一种可能的实现方式中，移动性管理网元触发第一会话从第二网络切片迁移到第一网络切片，包括：移动性管理网元获取第一会话在第三网络切片的上下文信息，第三网络切片为第一会话在终端设备的归属地网络关联的网络切片；移动性管理网元向第一会话管理网元发送第二消息，所述第二消息包括第一会话在第三网络切片的上下文信息，第二消息用于请求第一用户面网元与第三用户面网元之间的用户面资源的建立。这将结合后面的图7中的“方式二”进一步描述。
其中，第一会话管理网元为第一网络切片中服务第一会话的会话管理网元，第一用户面网元为第一网络切片中服务第一会话的用户面网元，第三用户面网元为第三网络切片中服务第一会话的用户面网元，第三网络切片为第一会话在终端设备的归属地网络关联的网络切片。
上述方案的具体实现将在后面图7、图9或图10所示的交互实施例中结合具体场景详细阐述，在此不予赘述。
现有技术中，当终端设备移出第二网络切片的服务范围，移动性管理网元触发对 应的会话管理网元执行会话的释放流程，这样，会话就中断了，因此无法保持会话的连续性。本申请实施例提供的网络切片选择的方法，对于已经建立的终端设备的第一会话，当终端设备移出第二网络切片的服务范围，若移动性管理网元确定终端设备的拜访地网络中的第一网络切片能够服务终端设备的第一会话，则触发第一会话从第二网络切片迁移到第一网络切片，从而可以保持会话的连续性。
如图6所示，为本申请实施例提供的另一种网络切片选择的方法，该方法包括如下步骤：
S601、第一接入网设备接收来自第二接入网设备的第一网络切片的单网络切片选择辅助信息(single network slice selection assistance information，S-NSSAI)和第二网络切片的S-NSSAI。
其中，第一网络切片和第二网络切片是终端设备的第一会话在终端设备的拜访地网络与第三网络切片具有映射关系的网络切片，且第二网络切片为第一会话在拜访地网络当前关联的网络切片，第三网络切片为第一会话在终端设备的归属地网络关联的网络切片。
S602、第一接入网设备确定不支持第二网络切片，支持第一网络切片。
S603、第一接入网设备向移动性管理网元发送第一指示信息，第一指示信息用于指示第一网络切片能够服务第一会话。
上述方案的具体实现将在后面图11所示的交互实施例中结合具体场景详细阐述，在此不予赘述。
现有技术中，当终端设备移出第二网络切片的服务范围，移动性管理网元触发对应的会话管理网元执行会话的释放流程，这样，会话就中断了，因此无法保持会话的连续性。本申请实施例提供的网络切片选择的方法，对于已经建立的终端设备的第一会话，当终端设备移出第二网络切片的服务范围，若第一接入网设备确定支持第一网络切片，可以向移动性管理网元发送用于指示第一网络切片能够服务第一会话的第一指示信息，进而由移动性管理网元触发第一会话从第二网络切片迁移到第一网络切片，从而可以保持会话的连续性。
下面将结合图1至图6对本申请实施例提供的网络切片选择的方法进行具体阐述。
需要说明的是，本申请下述实施例中各个网元之间的消息名字或消息中各参数的名字等只是一个示例，具体实现中也可以是其他的名字，本申请实施例对此不作具体限定。
首先，以图2a所示的通信系统应用于如图3a所示的5G网络为例，如图7所示，为本申请实施例提供的一种网络切片选择的方法，该网络切片选择的方法应用在移动性注册更新流程中，包括如下步骤：
S701、处于空闲状态的终端设备发起移动性注册更新流程，通过第一RAN设备向AMF网元发送消息a。相应的，AMF网元接收来自终端设备的消息a。
其中，消息a携带全球唯一临时UE标识(globally unique temporary UE identity，5G-GUTI)和请求的NSSAI(requested NSSAI)等参数，第一RAN设备可以根据5G-GUTI寻址AMF网元，在此不予赘述。
此外，需要说明的是，本申请实施例中的AMF网元位于终端设备的拜访地网络， 在此统一说明，以下不再赘述。
示例性的，本申请实施例中的消息a例如可以为如图7所示的移动性注册请求(registration request)消息或者周期性注册更新请求消息，本发明不做限定。
S702、AMF网元确定终端设备移出了第二网络切片的服务范围，且终端设备当前位于第一网络切片的服务范围内。其中，第一网络切片与第三网络切片具有映射关系，第三网络切片为终端设备的第一会话在终端设备的归属地网络关联的网络切片。
可选的，本申请实施例中，AMF网元可以根据存储的终端设备的上下文获知该终端设备已经建立第一会话。若该第一会话是家乡路由(home-routed)模式的会话，AMF网元进一步确定第一会话对应的拜访地网络S-NSSAI(visited PLMN S-NSSAI，V-S-NSSAI)和归属地网络S-NSSAI(home PLMN S-NSSAI，H-S-NSSAI)，同时，AMF网元根据终端设备当前的位置信息(如跟踪区标识(tracking area identity，TAI))确定终端设备移出了V-S-NSSAI所指示的第二网络切片的服务范围。进一步的，AMF网元可以确定终端设备的当前位置是否存在其他网络切片与H-S-NSSAI所指示的第三网络切片具有映射关系。
一种可能的实现方式中，AMF网元可以确定终端设备的当前位置是否存在其他网络切片与H-S-NSSAI所指示的第三网络切片具有映射关系，例如：AMF网元根据存储的VPLMN和HPLMN的漫游协议，确定终端设备的当前位置是否存在其他网络切片与第三网络切片具体映射关系。比如，终端设备当前位于第一网络切片的服务范围内，该漫游协议中包括第三网络切片的S-NSSAI(即H-S-NSSAI)和第一网络切片的S-NSSAI的映射关系，则AMF网元可以确定终端设备的当前位置存在第一网络切片与H-S-NSSAI所指示的第三网络切片具有映射关系。
另一种可能的实现方式中，AMF网元可以确定终端设备的当前位置是否存在其他网络切片与H-S-NSSAI所指示的第三网络切片具有映射关系，例如：AMF网元向NSSF网元发送查询消息，该查询消息携带终端设备的归属PLMN ID(即HPLMN ID)、终端设备当前的位置信息和第三网络切片的NSSAI(即H-S-NSSAI)，用于请求在终端设备的当前位置能映射到第三网络切片的终端设备的拜访地网络的网络切片的信息；进而，AMF网元接收来自NSSF网元的终端设备在拜访地网络允许的NSSAI(allowed NSSAI)、以及允许的NSSAI和第三网络切片的NSSAI的映射关系(mapping of allowed NSSAI)，其中，允许的NSSAI中包括第一网络切片的S-NSSAI，从而，AMF网元可以确定终端设备的当前位置存在第一网络切片与H-S-NSSAI所指示的第三网络切片具有映射关系。
进一步的，本申请实施例中，由于AMF网元确定终端设备的当前位置存在第一网络切片与H-S-NSSAI所指示的第三网络切片具有映射关系，因此AMF网元可以确定保留第一会话，但是更新第一会话对应的V-S-NSSAI，即AMF网元触发第一会话从第二网络切片迁移到第一网络切片。下面给出AMF网元触发第一会话从第二网络切片迁移到第一网络切片的两种实现方式。
一种可能的实现方式中，AMF触发第一V-SMF网元重建第一会话的N9隧道(如第一V-UPF网元和H-UPF网元之间的N9隧道)，但是由于该终端设备处于空闲态，因此在移动性注册更新流程中，第一会话的N3隧道无需建立(如第一V-UPF网元和 第一RAN设备之间的N3隧道)，其中，第一V-SMF网元是AMF网元根据第一网络切片的S-NSSAI选择的。具体的，如图7所示，本申请实施例提供的网络切片选择的方法还包括如下步骤S703a-S708a：
S703a、AMF网元向第一V-SMF网元发送消息b。相应的，第一V-SMF网元接收来自AMF网元的消息b。其中，消息b用于请求第一V-UPF网元与H-UPF网元之间的用户面资源的建立。
可选的，本申请实施例中的消息b中可以携带第一会话的会话标识，第一网络切片的S-NSSAI，H-SMF网元的标识，H-S-NSSAI。其中，第一会话的会话标识为AMF网元根据终端设备的上下文确定的终端设备之前建立的第一会话的标识，H-SMF网元的标识用于标识H-SMF网元，H-S-NSSAI为第一会话在终端设备的HPLMN关联的S-NSSAI，即第三网络切片的S-NSSAI。可选的，消息b还可以携带指示信息a，该指示信息a用来指示第一V-SMF网元只建立第一会话对应的N9隧道，N3隧道不用建立。
示例性的，本申请实施例中的消息b例如可以为如图7所示的创建会话管理(session management，SM)上下文请求(create SM context request)消息。当然，本申请实施例中的消息b还可以是服务化调用Nsmf_PDUSession_CreateSMContext，本申请实施例对此不做具体限定。
S704a、第一V-SMF网元根据第一网络切片的S-NSSAI选择第一V-UPF网元，并获得第一V-UPF网元和H-UPF网元之间的第一N9隧道的第一隧道信息。
其中，该第一隧道信息可以是第一V-SMF网元分配的，也可以是第一V-UPF网元分配的，本申请实施例对此不作具体限定。此外，该第一隧道信息可以理解为第一会话对应的第一N9隧道的下行隧道信息，在此统一说明，以下不再赘述。
示例性的，该第一隧道信息例如可以为第一N9隧道在第一V-UPF网元侧的隧道标识(可以记为核心网隧道标识(CN tunnel ID))。
S705a、第一V-SMF网元根据H-SMF网元的标识寻址第一会话对应的H-SMF网元，并向H-SMF网元发送消息c。相应的，H-SMF网元接收来自第一V-SMF网元的消息c。
其中，该消息c携带第一会话的会话标识，第一V-SMF网元的标识，H-S-NSSAI和第一N9隧道的第一隧道信息，用于请求H-SMF网元为第一会话更新N9隧道的上下文。
当然，本申请实施例中，H-SMF网元接收消息c之后，可以向H-UPF网元发送第一N9隧道的第一隧道信息，以便于后续H-UPF网元可以向第一V-UPF网元发送下行数据，本申请实施例对此不作具体限定。
示例性的，本申请实施例中的消息c例如可以为如图7所示的更新SM上下文请求(update SM context request)消息。当然，本申请实施例中的消息c也可以为服务化调用Nsmf_PDUSession_UpdateSMContext，本申请实施例对此不做具体限定。
S706a、H-SMF网元向第一V-SMF网元发送消息d。相应的，第一V-SMF网元接收来自H-SMF网元的消息d。
其中，该消息d携带第一V-UPF网元和H-UPF网元之间的第一N9隧道的第二隧 道信息。该第二隧道信息可以是H-SMF网元分配的，也可以是H-UPF网元分配的，本申请实施例对此不作具体限定。此外，该第二隧道信息可以理解为第一会话对应的第一N9隧道的上行隧道信息，在此统一说明，以下不再赘述。
示例性的，该第二隧道信息例如可以为第一N9隧道在H-UPF网元侧的隧道标识。
当然，本申请实施例中，第一V-SMF网元接收消息d之后，可以向第一V-UPF网元发送第一N9隧道的第二隧道信息，以便于后续第一V-UPF网元可以向H-UPF网元发送上行数据，本申请实施例对此不作具体限定。
示例性的，本申请实施例中的消息d例如可以为如图7所示的更新SM上下文响应(update SM context response)消息。当然，本申请实施例中的消息d还可以是服务化调用Nsmf_PDUSession_UpdateSMContext response，本申请实施例对此不做具体限定。
S707a、第一V-SMF网元向AMF网元发送消息e。相应的，AMF网元接收来自第一V-SMF网元的消息e。
示例性的，本申请实施例中的消息e例如可以为如图7所示的创建SM上下文响应(create SM context response)消息。当然，本申请实施例中的消息e还可以是服务化调用Nsmf_PDUSession_UpdateSMContext response，本申请实施例对此不做具体限定。
S708a、H-SMF网元向第二V-SMF网元发送消息f。相应的，第二V-SMF网元接收来自H-SMF网元的消息f。其中，消息f携带第一会话的会话标识，用于触发第二V-SMF网元释放第一会话的会话上下文。
示例性的，本申请实施例中的消息f例如可以为如图7所示的释放SM上下文请求(release SM context request)消息。当然，本申请实施例中的消息f还可以是服务化调用Nsmf_PDUSession_ReleaseSMContext，本申请实施例对此不做具体限定。
可选的，第二V-SMF网元还可以在释放第一会话的会话上下文之后，向H-SMF网元发送释放SM上下文响应(release SM context response)消息，本申请实施例对此不做具体限定。
另一种可能的实现方式中，AMF网元从第二V-SMF获取H-SMF网元分配的第一会话的会话上下文，并将H-SMF网元分配的第一会话的会话上下文发送至第一V-SMF网元，触发第一V-SMF网元与H-SMF网元更新第一会话的N9隧道，其中，第一V-SMF网元是AMF网元根据第一网络切片的S-NSSAI选择的。具体的，如图7所示，本申请实施例提供的网络切片选择的方法还包括如下步骤S703b-S709b：
S703b、AMF网元向第二V-SMF网元发送消息g。相应的，第二V-SMF网元接收来自AMF网元的消息g。
其中，消息g携带第一会话的会话标识，用于请求H-SMF网元分配的第一会话的会话上下文。该会话上下文中包括H-SMF网元或者H-UPF网元为第二V-UPF网元和H-UPF网元之间的第二N9隧道的第三隧道信息。此外，该第三隧道信息也可以理解为第一会话对应的第二N9隧道的上行隧道信息，在此统一说明，以下不再赘述。
示例性的，该第三隧道信息例如可以为第二N9隧道在H-UPF网元侧的隧道标识。
示例性的，本申请实施例中的消息g例如可以为如图7所示的上下文请求(context  request)消息。
S704b、第二V-SMF网元向AMF网元发送消息h。相应的，AMF网元接收来自第二V-SMF网元的消息h。其中，该消息h携带H-SMF网元分配的第一会话的会话上下文。
示例性的，本申请实施例中的消息h例如可以为如图7所示的上下文响应(context response)消息。
可选的，本申请实施例中，第二V-SMF网元还可以设置定时器(timer)，等定时器超时后，第二V-SMF网元可以在本地释放第一会话的上下文，本申请实施例对此不做具体限定。
S705b、AMF网元向第一V-SMF网元发送消息i。相应的，第一V-SMF网元接收来自AMF网元的消息i。其中，消息i用于请求第一V-UPF网元与H-UPF网元之间的用户面资源的建立。
可选的，本申请实施例中的消息i中可以携带第一会话的会话标识，第一网络切片的S-NSSAI，H-SMF网元的标识和H-SMF网元分配的第一会话的会话上下文。其中，第一会话的会话标识为AMF网元根据终端设备的上下文确定的终端设备之前建立的第一会话的标识，H-SMF网元的标识用于标识H-SMF网元。
示例性的，本申请实施例中的消息i例如可以为如图7所示的创建SM上下文请求(create SM context request)消息。
S706b、第一V-SMF网元根据第一网络切片的S-NSSAI选择第一V-UPF网元，并获得第一V-UPF网元和H-UPF网元之间的第一N9隧道的第一隧道信息。
其中，该第一隧道信息可以是第一V-SMF网元分配的，也可以是第一V-UPF网元分配的，本申请实施例对此不作具体限定。
示例性的，该第一隧道信息例如可以为第一N9隧道在第一V-UPF网元侧的隧道标识。
当然，本申请实施例中，第一V-SMF网元选择第一V-UPF网元之后，可以向第一V-UPF网元发送第二V-UPF网元和H-UPF网元之间的第二N9隧道的第三隧道信息。会话迁移之前，该第三隧道信息是为了第二V-UPF网元可以向H-UPF网元发送上行数据。由于会话迁移之后，H-UPF网元不变，因此该第三隧道信息可以重用，即为第一V-UPF网元和H-UPF网元之间的第一N9隧道的第二隧道信息。这样以便于后续第一V-UPF网元可以向H-UPF网元发送上行数据，本申请实施例对此不作具体限定。
S707b、第一V-SMF网元根据H-SMF网元的标识寻址第一会话对应的H-SMF网元，并向H-SMF网元发送消息j。相应的，H-SMF网元接收来自第一V-SMF网元的消息j。
其中，该消息j携带第一会话的会话标识，第一V-SMF网元的标识，H-S-NSSAI、第一N9隧道的第一隧道信息以及H-SMF网元分配的第一会话的会话上下文，用于请求H-SMF网元与第一V-SMF网元创建上下文。
其中，本申请实施例中，消息j中携带H-SMF网元分配的第一会话的会话上下文是为了请求H-SMF网元更新H-SMF网元上存储的第一会话的会话上下文。具体的， H-SMF网元可以将H-SMF网元上存储的第一会话的会话上下文中保存的第二V-UPF网元和H-UPF网元之间的第二N9隧道的第四隧道信息替换为第一V-UPF网元和H-UPF网元之间的第一N9隧道的第一隧道信息。此外，该第四隧道信息可以理解为第一会话对应的第二N9隧道的下行隧道信息，在此统一说明，以下不再赘述。
示例性的，该第四隧道信息例如可以为第二N9隧道在第二V-UPF网元侧的隧道标识。
当然，本申请实施例中，H-SMF网元接收消息j之后，可以向H-UPF网元发送第一N9隧道的第一隧道信息，以便于后续H-UPF网元可以向第一V-UPF网元发送下行数据，本申请实施例对此不作具体限定。
为方便理解，如图8所示，为本申请实施例提供的第一会话迁移前后的N9隧道示意图。其中，图8中的(a)为第一会话迁移之前的N9隧道示意图，图8中的(b)为第一会话迁移之后的N9隧道示意图，可以看出，第二隧道信息和第三隧道信息均是H-UPF网元侧的隧道信息，因此在第一会话迁移前后可以保持不变，即第二隧道信息和第三隧道信息可以相同。但是，由于第一会话迁移前后的V-UPF网元发生了改变，因此H-UPF网元侧的第四隧道信息被替换为第一隧道信息。
示例性的，本申请实施例中的消息j例如可以为如图7所示的更新SM上下文请求(update SM context request)消息。
S708b、H-SMF网元向第一V-SMF网元发送消息k。相应的，第一V-SMF网元接收来自H-SMF网元的消息k。
示例性的，本申请实施例中的消息k例如可以为如图7所示的更新SM上下文响应(update SM context response)消息。
S709b、第一V-SMF网元向AMF网元发送消息l。相应的，AMF网元接收来自第一V-SMF网元的消息l。
示例性的，本申请实施例中的消息l例如可以为如图7所示的创建SM上下文响应(create SM context response)消息。
其中，基于上述步骤S703a-S708a或者步骤S703b-S709b，第一会话在核心网侧可以迁移成功。进一步的，如图7所示，本申请实施例提供的网络切片选择的方法还包括如下步骤：
S710、AMF网元向终端设备发送消息m。相应的，终端设备接收来自AMF网元的消息m。
其中，消息m携带更新后的允许的NSSAI、以及第一网络切片的S-NSSAI和第三网络切片的S-NSSAI的映射关系，其中，更新后的允许的NSSAI中包括第一网络切片的S-NSSAI。
示例性的，本申请实施例中的消息m例如可以为如图7所示的移动性注册接受(registration accept)消息。
S711、AMF网元向第一V-SMF网元发送消息n。相应的，第一V-SMF网元接收来自AMF网元的消息n。其中，消息n中携带指示信息b，指示信息b用于指示第一V-SMF网元发起第一会话的修改流程，来通知终端设备该第一会话的V-S-NSSAI已经发生了变化。
示例性的，本申请实施例中的消息n例如可以为如图7所示的PDU会话更新SM上下文(PDU session update SM context)消息。
需要说明的是，本申请实施例中的指示信息b也可以称之为第一指示信息，在此统一说明，本申请实施例对此不作具体限定。
S712、第一V-SMF网元根据消息n中的指示发起会话修改流程。具体的，第一V-SMF网元向AMF网元发送消息o。相应的，AMF网元接收来自第一V-SMF网元的消息o。其中，消息o携带N2 SM容器(N2 SM container)和PDU会话修改命令(PDU session modification command)。N2 SM容器中包括第一会话的会话标识和第一网络切片的S-NSSAI；PDU会话修改命令中包括第一会话的会话标识、第一网络切片的S-NSSAI和第三网络切片的S-NSSAI。其中，第一网络切片的S-NSSAI为第一会话对应的修改后的V-S-NSSAI，第三网络切片的S-NSSAI为第一会话对应的H-S-NSSAI。
示例性的，本申请实施例中的消息o例如可以为如图7所示的N1N2消息传输(N1N2 message transfer)消息。
S713、AMF网元向第一RAN设备发送消息p。相应的，第一RAN设备接收来自AMF网元的消息p。其中，该消息p携带N2 SM容器(N2 SM container)和PDU会话修改命令(PDU session modification command)。
示例性的，本申请实施例中的消息p例如可以为如图7所示的N2消息(N2 message)。
S714、第一RAN设备向终端设备发送消息q。相应的，终端设备接收来自第一RAN设备的消息q。其中，消息q携带上述PDU会话修改命令。
示例性的，本申请实施例中的消息q例如可以为如图7所示的NAS消息(NAS message)。
至此，终端设备获知与第一会话的H-S-NSSAI对应的第一网络切片的S-NSSAI(即V-S-NSSAI)，从而可以将本地存储的第一会话对应的第二网络切片的S-NSSAI修改为当前位置下可以服务第一会话的第一网络切片的S-NSSAI。
现有技术中，当终端设备移出第二网络切片的服务范围，AMF网元触发对应的SMF网元(如本申请实施例中的第二V-SMF网元)执行会话的释放流程，这样，会话就中断了，因此无法保持会话的连续性。然而，采用本申请实施例提供的网络切片选择的方法，对于已经建立的终端设备的第一会话，当终端设备移出第二网络切片的服务范围，若AMF网元确定终端设备的拜访地网络中的第一网络切片能够服务终端设备的第一会话，则触发第一会话从第二网络切片迁移到第一网络切片，从而可以保持会话的连续性。
其中，上述步骤S701至S713中的AMF网元或者第一V-SMF网元的动作可以由图4所示的通信设备400中的处理器401调用存储器403中存储的应用程序代码来执行，本实施例对此不作任何限制。
现有技术中，当终端设备的第一会话处于激活状态，且该终端设备从第二RAN设备切换到第一RAN设备时，第一RAN设备会判断自己是否支持该第一会话对应的网络切片，如果不支持该第一会话对应的网络切片，第一RAN设备会拒绝第一会话从第二RAN设备切换到第一RAN设备，即第一会话切换失败，从而导致第一会话无法保 持会话的连续性。
为解决该问题，一种可能的实现方式中，以图2b所示的通信系统应用于如图3b所示的5G网络为例，如图9所示，为本申请实施例提供的一种网络切片选择的方法，该网络切片选择的方法应用在切换流程中，包括如下步骤：
S901、第一RAN设备向AMF网元发送消息r。相应的，AMF网元接收来自第一RAN设备的消息r。其中，消息r携带第一RAN设备对应的TAI以及携带拒绝原因值的PDU会话拒绝列表(list of PDU sessions rejected with a rejection cause)。拒绝列表中包括终端设备的第一会话的会话标识，拒绝原因为第一RAN设备不支持第一会话在终端设备的拜访地网络关联的第二网络切片。
示例性的，本申请实施例中的消息r例如可以为如图9所示的N2路径切换请求(N2 path switch request)消息。
S902、AMF网元确定终端设备移出了第二网络切片的服务范围，且终端设备当前位于第一网络切片的服务范围内。其中，第一网络切片与第三网络切片具有映射关系，第三网络切片为终端设备的第一会话在终端设备的归属地网络关联的网络切片。
可选的，本申请实施例中，AMF网元可以根据携带拒绝原因的PDU会话拒绝列表，确定终端设备移出了第二网络切片的服务范围。进一步的，AMF网元可以确定终端设备的当前位置是否存在其他网络切片与H-S-NSSAI所指示的第三网络切片具有映射关系。其中，AMF网元确定终端设备的当前位置是否存在其他网络切片与
H-S-NSSAI所指示的第三网络切片具有映射关系的方式可参考图7所示的实施例中的步骤S702，在此不再赘述。
进一步的，本申请实施例中，由于AMF网元确定终端设备的当前位置存在第一网络切片与H-S-NSSAI所指示的第三网络切片具有映射关系，因此AMF网元可以确定保留第一会话，但是更新第一会话对应的V-S-NSSAI，即AMF网元触发第一会话从第二网络切片迁移到第一网络切片。下面给出AMF网元触发第一会话从第二网络切片迁移到第一网络切片的两种实现方式。
一种可能的实现方式中，如图9所示，本申请实施例提供的网络切片选择的方法还包括如下步骤S903a-S908a：
S903a-S908a、同图7所示的实施例中的步骤S703a-S708a，相关描述可参考图7所示的实施例，在此不再赘述。
另一种可能的实现方式中，如图9所示，本申请实施例提供的网络切片选择的方法还包括如下步骤S903b-S909b：
S903b-S909b、同图7所示的实施例中的步骤S703b-S709b，相关描述可参考图7所示的实施例，在此不再赘述。
其中，基于上述步骤S903a-S908a或者步骤S903b-S909b，第一会话在核心网侧可以迁移成功。进一步的，如图9所示，本申请实施例提供的网络切片选择的方法还包括如下步骤：
S910、AMF网元向第一RAN设备发送消息s。相应的，第一RAN设备接收来自AMF网元的消息s。
示例性的，本申请实施例中的消息s例如可以为如图9所示的N2路径切换响应(N2  path switch response)消息。
其中，由于此时还未建立第一RAN设备和第一V-UPF网元之间的N3隧道以及第一会话的空口侧资源，因此为了使得第一会话在目标侧实现完整的切换，如图9所示，本申请实施例提供的网络切片选择的方法还包括如下步骤：
S911、终端设备发起移动性注册更新流程，通过第一RAN设备向AMF网元发送消息a’。相应的，AMF网元接收来自终端设备的消息a’。
其中，消息a’携带5G-GUTI、请求的NSSAI(requested NSSAI)和PDU会话状态(PDU session status)等参数。5G-GUTI用于寻址AMF网元，PDU会话状态表示终端设备当前建立的会话在终端设备侧的状态，如第二会话在终端设备侧处于激活状态，第三会话在终端设备侧处于去激活状态等。该PDU会话状态用于终端设备与核心网进行会话状态的同步，具体可参考现有的实现方式，在此不予赘述。
示例性的，本申请实施例中的消息a’例如可以为如图9所示的移动性注册请求(registration request)消息。
S912、AMF网元虽然在核心网侧保留了第一会话的锚点资源，但是第一会话在目标侧没有建立空口资源和N3隧道资源，因此AMF网元向终端设备发送消息m’。相应的，终端设备接收来自AMF网元的消息m’。其中，消息m’携带指示信息c，指示信息c用于指示终端设备发起第一会话关联的业务请求流程，该业务请求流程用于建立第一会话的空口资源，其中，第一会话的空口资源与第一网络切片关联。
示例性的，该指示信息c例如可以为第一会话的会话标识。
此外，可选的，该消息m’还可以携带核心网确认后的PDU会话状态、更新后的允许的NSSAI、以及第一网络切片的S-NSSAI和第三网络切片的S-NSSAI的映射关系，其中，更新后的允许的NSSAI中包括第一网络切片的S-NSSAI，确认后的PDU会话状态表示终端设备当前建立的所有会话在核心网侧的状态。其中，第一会话的会话标识、第一网络切片的S-NSSAI和第三网络切片的S-NSSAI可以用于终端设备更新第一会话在拜访地网络关联的S-NSSAI。
需要说明的是，本申请实施例中的指示信息c也可以称之为第三指示信息，在此统一说明，本申请实施例对此不作具体限定。
示例性的，本申请实施例中的消息m’例如可以为如图9所示的移动性注册接受(registration accept)消息。
S913、终端设备根据指示信息c发起业务请求流程，从而使得AMF网元建立第一RAN设备和第一V-UPF网元之间的N3隧道以及第一会话的空口侧资源，其中，该业务请求流程与现有技术中终端设备触发的业务请求流程一致，在此不再赘述。
需要说明的是，本申请实施例提供的业务请求流程中，AMF网元可以将第一网络设备的S-NSSAI和第一会话的会话标识发送给第一RAN设备，该第一网络设备的S-NSSAI和第一会话的会话标识用于更新第一会话在所述拜访地网络对应的S-NSSAI，本申请实施例对此不作具体限定。
现有技术中，当终端设备移出第二网络切片的服务范围，AMF网元触发对应的SMF网元(如本申请实施例中的第二V-SMF网元)执行会话的释放流程，这样，会话就中断了，因此无法保持会话的连续性。然而，采用本申请实施例提供的网络切片 选择的方法，对于已经建立的终端设备的第一会话，当终端设备移出第二网络切片的服务范围，若AMF网元确定终端设备的拜访地网络中的第一网络切片能够服务终端设备的第一会话，则触发第一会话从第二网络切片迁移到第一网络切片，从而可以保持会话的连续性。
其中，上述步骤S901至S913中的AMF网元或者第一V-SMF网元的动作可以由图4所示的通信设备400中的处理器401调用存储器403中存储的应用程序代码来执行，本实施例对此不作任何限制。
另一种可能的实现方式中，以图2b所示的通信系统应用于如图3b所示的5G网络为例，如图10所示，为本申请实施例提供的另一种网络切片选择的方法，该网络切片选择的方法应用在切换流程中，包括如下步骤：
S1001-S1010、同图9所示的实施例中的步骤S901-S910，相关描述可参考图9所示的实施例，在此不再赘述。
其中，由于此时还未建立第一RAN设备和第一V-UPF网元之间的N3隧道以及第一会话的空口侧资源，因此为了使得第一会话在目标侧实现完整的切换，如图10所示，本申请实施例提供的网络切片选择的方法还包括如下步骤：
S1011、同图9所示的实施例中的步骤S911，相关描述可参考图9所示的实施例，在此不再赘述。
S1012、AMF网元向第一V-SMF网元发送消息t。相应的，第一V-SMF网元接收来自AMF网元的消息t。其中，消息t携带第一会话的会话标识，用于请求第一V-SMF网元建立第一RAN设备和第一V-UPF网元之间的N3隧道以及第一会话的空口侧资源，该第一会话的空口资源与第一网络切片关联。
示例性的，本申请实施例中的消息t例如可以为如图10所示的更新SM上下文请求消息1。
S1013、第一V-SMF网元根据第一网络切片的S-NSSAI选择第一V-UPF网元，并向第一V-UPF网元发送消息u。相应的，第一V-UPF网元接收来自第一V-SMF网元的消息u。
可选的，消息u可以携带第一RAN设备和第一V-UPF网元之间的N3隧道的第五隧道信息，该第五隧道信息可以理解为第一会话对应的上行N3隧道信息。
示例性的，该第五隧道信息例如可以为该N3隧道在第一V-UPF网元的隧道标识。
示例性的，本申请实施例中的消息u例如可以为如图10所示的N4会话修改请求(N4 session modification request)消息1。
当然，第一V-UPF网元还可以向第一V-SMF网元发送N4会话修改响应(N4 session modification response)消息1，本申请实施例对此不作具体限定。
需要说明的是，本申请实施例中第一RAN设备和第一V-UPF网元之间的N3隧道的第五隧道信息也可以是由第一V-UPF网元分配的，此时上述N4会话修改响应消息1中携带该第五隧道信息，在此统一说明，以下不再赘述。
S1014、第一V-SMF网元向AMF网元发送消息v。相应的，AMF网元接收来自第一V-SMF网元的消息v。其中，消息v携带N2 SM信息，该N2 SM信息包括第一网络切片的S-NSSAI、QoS文件以及第一RAN设备和第一V-UPF网元之间的N3隧 道的第五隧道信息，该第五隧道信息用于后续第一RAN设备通过N3隧道可以向第一V-UPF网元发送上行数据。
示例性的，本申请实施例中的消息v例如可以为如图10所示的更新SM上下文响应消息1。
S1015、AMF网元向第一RAN设备发送消息w。相应的，第一RAN设备接收来自AMF网元的消息w。其中，消息w中包括上述N2 SM信息以及注册接受消息，该注册接受消息中包括确认后的PDU会话状态、更新后的允许的NSSAI、以及第一网络切片的S-NSSAI和第三网络切片的S-NSSAI的映射关系，其中，更新后的允许的NSSAI中包括第一网络切片的S-NSSAI。
示例性的，本申请实施例中的消息w例如可以为如图10所示的N2请求消息。
S1016、第一RAN设备向终端设备发送注册接受消息。相应的，终端设备接收来自第一RAN设备的注册接受消息。
S1017、第一RAN设备向AMF网元发送消息x。相应的，AMF网元接收来自第一RAN设备的消息x。其中，消息x携带第一RAN设备分配的第一RAN设备和第一V-UPF网元之间的N3隧道的第六隧道信息，该第六隧道信息可以理解为第一会话对应的下行N3隧道信息。
示例性的，该第六隧道信息例如可以包括该N3隧道在第一RAN设备侧的隧道标识。
示例性的，本申请实施例中的消息x例如可以为如图10所示的N2请求确认消息。
S1018、AMF网元向第一V-SMF网元发送消息y。相应的，第一V-SMF网元接收来自AMF网元的消息y。其中，消息y携带第一RAN设备和第一V-UPF网元之间的N3隧道的第六隧道信息。
示例性的，本申请实施例中的消息y例如可以为如图10所示的更新SM上下文请求消息2。
S1019、第一V-SMF网元向第一V-UPF网元发送消息z。相应的，第一V-UPF网元接收来自第一V-SMF网元的消息z。其中，消息z携带第一RAN设备和第一V-UPF网元之间的N3隧道的第六隧道信息，该第六隧道信息用于后续第一V-UPF网元通过N3隧道可以向第一RAN设备发送下行数据。
示例性的，本申请实施例中的消息z例如可以为如图10所示的N4会话修改请求消息2。
当然，第一V-UPF网元还可以向第一V-SMF网元发送N4会话修改响应消息2，第一V-SMF网元还可以向AMF网元发送更新SM上下文响应消息2，本申请实施例对此不作具体限定。
现有技术中，当终端设备移出第二网络切片的服务范围，AMF网元触发对应的SMF网元(如本申请实施例中的第二V-SMF网元)执行会话的释放流程，这样，会话就中断了，因此无法保持会话的连续性。然而，采用本申请实施例提供的网络切片选择的方法，对于已经建立的终端设备的第一会话，当终端设备移出第二网络切片的服务范围，若AMF网元确定终端设备的拜访地网络中的第一网络切片能够服务终端设备的第一会话，则触发第一会话从第二网络切片迁移到第一网络切片，从而可以保 持会话的连续性。
其中，上述步骤S1001至S1019中的AMF网元或者第一V-SMF网元的动作可以由图4所示的通信设备400中的处理器401调用存储器403中存储的应用程序代码来执行，本实施例对此不作任何限制。
又一种可能的实现方式中，以图2b所示的通信系统应用于如图3b所示的5G网络为例，如图11所示，为本申请实施例提供的又一种网络切片选择的方法，该网络切片选择的方法应用在切换流程中，包括如下步骤：
S1101、终端设备发起会话建立流程，通过第二RAN设备向AMF网元发送消息1。相应的，AMF网元接收来自第二RAN设备的消息1。其中，消息1携带终端设备的第一会话的会话标识、第一会话在终端设备的归属地网络关联的第三网络切片的S-NSSAI(可以记为H-S-NSSAI)、以及第一会话在终端设备的拜访地网络当前关联的第二网络切片的S-NSSAI(可以记为V-S-NSSAI2)。其中，第二RAN设备支持第二网络切片。
示例性的，本申请实施例中的消息1例如可以为如图11所示的PDU会话建立请求(PDU session establishment request)消息。
S1102、AMF网元根据V-S-NSSAI2和H-S-NSSAI1分别选择第二V-SMF网元和H-SMF网元，并触发第二V-SMF网元与H-SMF网元在核心网侧创建会话上下文，相关实现可参考现有技术，在此不予赘述。
S1103、第二V-SMF网元向AMF网元发送消息2。相应的，AMF网元接收来自第二V-SMF网元的消息2。其中，消息2携带第一会话的会话标识、N2 SM信息和N1 SM容器(container)。N2 SM信息中包括第一会话的会话标识和V-S-NSSAI2，N2 SM容器中包括PDU会话建立接受(PDU session establishment accept)消息。
示例性的，本申请实施例中的消息2例如可以为如图11所示的N1N2消息传输请求(N1N2 message transfer request)消息。
S1104、AMF网元确定是否存在其他网络切片与H-S-NSSAI所指示的第三网络切片具有映射关系。
其中，一种可能的实现方式中，AMF网元确定是否存在其他网络切片与H-S-NSSAI所指示的第三网络切片具有映射关系可以包括：AMF网元根据存储的VPLMN和HPLMN的漫游协议，确定VPLMN内是否存在其他网络切片与第三网络切片具体映射关系。比如，终端设备当前位于第二网络切片的服务范围内，该漫游协议中包括第三网络切片的S-NSSAI(即H-S-NSSAI)和第一网络切片的S-NSSAI的映射关系，以及第三网络切片的S-NSSAI和第二网络切片的S-NSSAI的映射关系，则AMF网元可以确定在VPLMN内与H-S-NSSAI所指示的第三网络切片具有映射关系的网络切片除了第二网络切片之外，还有第一网络切片。
另一种可能的实现方式中，AMF网元确定是否存在其他网络切片与H-S-NSSAI所指示的第三网络切片具有映射关系，可以包括：AMF网元向NSSF网元发送查询消息，该查询消息携带终端设备的归属PLMN ID(即HPLMN ID)和第三网络切片的NSSAI(即H-S-NSSAI)，用于请求在VPLMN内能映射到第三网络切片的终端设备的拜访地网络的网络切片的信息；进而，AMF网元接收来自NSSF网元的第一网络切 片的S-NSSAI和第二网络切片的S-NSSAI，其中第一网络切片的S-NSSAI和第二网络切片的S-NSSAI分别和第三网络切片的NSSAI的存在映射关系，从而，AMF网元可以确定在VPLMN内与H-S-NSSAI所指示的第三网络切片具有映射关系的网络切片除了第二网络切片之外，还有第一网络切片。
当AMF网元确定存在除第二网络切片之外的第一网络切片与H-S-NSSAI所指示的第三网络切片具有映射关系，则本申请实施例提供的网络切片选择的方法还包括如下步骤：
S1105、AMF网元向第二RAN设备发送消息3。相应的，第二RAN设备接收来自AMF网元的消息3。该消息3携带第二网络切片的S-NSSAI、第一网络切片的S-NSSAI、N2 SM信息和N1 SM容器(container)。
其中，本申请实施例中，第二RAN设备接收来自AMF网元的消息3之后，可以存储第二网络切片的S-NSSAI、第一网络切片的S-NSSAI以及N2 SM信息。
需要说明的是，本申请实施例中，第二RAN设备支持第二网络切片，不支持第一网络切片。本申请实施例以假设AMF网元确定存在除第二网络切片之外的第一网络切片与H-S-NSSAI所指示的第三网络切片具有映射关系为例进行说明，当然，也可能是存在除第二网络切片之外的其它网络切片与H-S-NSSAI所指示的第三网络切片具有映射关系，处理方法与本申请实施例类似，在此不再赘述。
示例性的，本申请实施例中的消息3例如可以为如图11所示的N2 PDU会话请求(N2 PDU session request)消息。
S1106、第二RAN设备向终端设备发送消息4。相应的，终端设备接收来自第二RAN设备的消息4。其中，消息4中包括N1 SM容器。
示例性的，本申请实施例中的消息4例如可以为如图11所示的NAS消息。
S1107、当终端设备发生了移动，执行Xn切换时，第二RAN设备向第一RAN设备部发送消息5。相应的，第一RAN设备接收来自第二RAN设备的消息5。其中，消息5携带第一网络切片的S-NSSAI和第二网络切片的S-NSSAI。
示例性的，如图11所示，本申请实施例中的消息5例如可以为切换请求(handover request)消息。
S1108、若第一RAN设备确定第一RAN设备不支持第二网络切片，第一RAN设备支持第一网络切片，则认为第一会话可以成功切换，进而第一RAN设备可以向AMF网元发送消息6。相应的，AMF网元接收来自第一RAN设备的消息6。其中，消息6携带指示信息d，指示信息d用于指示第一网络切片能够服务第一会话。
可选的，该指示信息6例如可以为第一会话的会话标识和第一网络切片的S-NSSAI。
示例性的，本申请实施例中的消息6例如可以为如图11所示的N2路径切换请求消息。
进一步的，AMF网元获知第一网络切片能够服务第一会话之后，可以触发第一会话从第二网络切片迁移到第一网络切片，以及建立第一RAN设备和第一V-UPF网元之间的N3隧道以及第一会话的空口侧资源，相关实现可参考图9所示的实施例中的步骤S903a-S913或者步骤S903b-S913，或者相关实现可参考图10所示的实施例中的 步骤S1003a-S1019或者步骤S1003b-S1019，在此不予赘述。
现有技术中，当终端设备移出第二网络切片的服务范围，AMF网元触发对应的SMF网元(如本申请实施例中的第二V-SMF网元)执行会话的释放流程，这样，会话就中断了，因此无法保持会话的连续性。然而，采用本申请实施例提供的网络切片选择的方法，对于已经建立的终端设备的第一会话，当终端设备移出第二网络切片的服务范围，若AMF网元确定终端设备的拜访地网络中的第一网络切片能够服务终端设备的第一会话，则触发第一会话从第二网络切片迁移到第一网络切片，从而可以保持会话的连续性。
其中，上述步骤S1101至S1108中的AMF网元或者第一V-SMF网元的动作可以由图4所示的通信设备400中的处理器401调用存储器403中存储的应用程序代码来执行，本实施例对此不作任何限制。
现有技术中，当终端设备处于连接态，随着终端设备的移动会触发切换流程。若源RAN设备与终端设备待切换的目标RAN设备之间存在Xn接口，就会通过Xn接口的切换流程将终端设备切换到目标侧。然而，现有的Xn接口切换流程中，若目标RAN设备不支持终端设备的会话关联的网络切片，则拒绝终端设备的会话切换到目标侧，从而导致该会话无法在目标侧保持会话连续性，影响终端设备的业务体验。为解决该问题，本申请实施例引入同一个PLMN内的切片映射关系：将不同区域覆盖的切片之间形成映射关系，保证终端设备离开切片覆盖区域之后，会话锚点保持不变，从而实现业务连续性。比如，如图17所示，切片X和切片Y的覆盖范围均为有限的地理区域，即终端设备只能位于切片X或者切片Y的覆盖范围内，才能接入该切片，同时网络中还部署一个切片A，且该切片A与切片X存在映射关系，与切片Y也存在映射关系。这样，当终端设备移入切片X或切片Y的覆盖范围且建立了切片X或切片Y对应的会话之后，如果终端设备移出切片X或切片Y的覆盖范围，由于切片A与切片X或切片Y存在映射关系，终端设备可以通过接入切片A连接到该会话的锚点，保证该会话的业务连续性。
下面将以结合图18至图20对本申请实施例提供的网络切片选择的方法进行具体阐述。
首先，以图14所示的通信系统应用于如图16所示的5G网络为例，如图18所示，为本申请实施例提供的一种网络切片选择的方法，该网络切片选择的方法中，RAN设备(包括下述的第一RAN设备和第二RAN设备)在N2建立(N2 setup)流程中获取切片映射信息(slice mapping)。比如，在N2连接建立(N2 connection setup)过程中，AMF网元将slice mapping下发至RAN设备，由RAN设备本地保存，其中，AMF网元获取slice mapping的方式可以是本地配置，或者从NSSF网元获取。后续Xn切换过程中，第一RAN设备可以基于slice mapping以及当前会话的S-NSSAI确定出匹配的S-NSSAI(mapped S-NSSAI)。具体的，图18所示的网络切片选择的方法包括如下步骤：
S1801、AMF网元获取第一映射关系列表，该第一映射关系列表包括AMF网元支持的每个网络切片的切片映射信息。
示例性的，假设AMF网元支持的每个网络切片的S-NSSAI分别为S-NSSAI-X、 S-NSSAI-Y和S-NSSAI-Z，S-NSSAI-X指示的网络切片与S-NSSAI-A指示的网络切片具有映射关系，S-NSSAI-Y指示的网络切片与S-NSSAI-B指示的网络切片具有映射关系，S-NSSAI-Z指示的网络切片与S-NSSAI-C指示的网络切片具有映射关系，则第一映射关系列表可以如表一所示：
表一
Figure PCTCN2020115959-appb-000001
其中，两个网络切片具有映射关系的相关描述可参考前述实施例，在此不再赘述。
需要说明的是，虽然表一所示的映射关系是一对一映射，但是本申请实施例中，网络切片的映射关系也可以是一对多映射，即，可以有多个网络切片与某个网络切片具有映射关系，本申请实施例对此不做具体限定。
需要说明的是，本申请实施例中，与AMF网元支持的网络切片具有映射关系的网络切片可以简称为映射的网络切片。其中，AMF网元可以支持所有映射的网络切片，比如，结合表一，AMF网元可以支持S-NSSAI-A指示的网络切片，S-NSSAI-B指示的网络切片和S-NSSAI-C指示的网络切片。或者，AMF网元可以不支持任何一个映射的网络切片，比如，结合表一，AMF网元可以不支持S-NSSAI-A指示的网络切片，S-NSSAI-B指示的网络切片和S-NSSAI-C指示的网络切片。或者，AMF网元可以支持部分映射的网络切片，比如，结合表一，AMF网元可以支持S-NSSAI-A指示的网络切片，S-NSSAI-B指示的网络切片或者S-NSSAI-C指示的网络切片中的一个或两个。本申请实施例对AMF网元是否支持映射的网络切片不做具体限定。
一种可能的实现方式中，AMF网元可以本地配置第一映射关系列表。相应的，AMF网元获取第一映射关系列表，包括：AMF网元获取预配置的第一映射关系列表。
另一种可能的实现方式中，AMF网元本地未配置第一映射关系列表。相应的，AMF网元获取第一映射关系列表，包括：AMF网元从NSSF网元获取第一映射关系列表。具体的，AMF网元可以向NSSF网元发送切片映射请求(slice mapping request)，该切片映射请求包括AMF网元支持的网络切片的NSSAI。进而，NSSF网元可以根据AMF网元支持的网络切片的NSSAI，确定第一映射关系列表，并向AMF网元发送切片映射响应(slice mapping response)，该切片映射响应包括第一映射关系列表。
需要说明的是，本申请实施例中的映射关系列表也可以称之为映射关系集合，本申请实施例对此不做具体限定。
S1802a、第一RAN设备向AMF网元发送N2消息1。相应的，AMF网元接收来自第一RAN设备的N2消息1。
其中，该N2消息1包括第一RAN设备的信息和第一RAN设备支持的切片信息列表(这里的切片信息列表也可以称为切片信息集合)。
可选的，本申请实施例中，第一RAN设备的信息可以包括第一RAN设备的标识或者第一RAN设备所在的跟踪区(tracking area，TA)等，本申请实施例对此不做具 体限定。
可选的，本申请实施例中的N2消息1可以是N2连接请求(N2 connection request)消息或者NG建立请求(NG setup request)消息等，本申请实施例对此不做具体限定。
需要说明的是，本申请实施例以第一RAN设备与一个AMF网元交互为例进行说明。当然，若第一RAN设备与多个AMF网元之间存在N2接口(或NG接口)，则第一RAN设备需要向多个AMF网元分别发送上述N2消息1，本申请实施例对此不做具体限定。
示例性的，假设第一RAN设备支持的网络切片包括S-NSSAI-A指示的网络切片和S-NSSAI-C指示的网络切片，则第一RAN设备支持的切片信息列表可以如表二所示：
表二
Figure PCTCN2020115959-appb-000002
S1803a、AMF网元向第一RAN设备发送N2消息2。相应的，第一RAN设备接收来自AMF网元的N2消息2。
例如，该N2消息2包括第一RAN设备支持的网络切片的切片映射信息。
示例性的，假设如表二所示，第一RAN设备支持的切片信息列表包括S-NSSAI-A和S-NSSAI-C，S-NSSAI-A指示的网络切片与S-NSSAI-X指示的网络切片具有映射关系，S-NSSAI-C指示的网络切片与S-NSSAI-Z指示的网络切片具有映射关系，则第一RAN设备支持的网络切片的切片映射信息可以如表三所示：
表三
Figure PCTCN2020115959-appb-000003
或者，该N2消息2可包括AMF网元支持的网络切片的S-NSSAI，以及与每个AMF网元支持的网络切片具有映射关系的网络切片的S-NSSAI。例如，第一RAN设备收到如上述表一的切片映射信息。
可选的，本申请实施例中，该N2消息2还可以包括AMF网元支持的网络切片的S-NSSAI。
可选的，本申请实施例中的N2消息2可以是N2连接响应(N2 connection response)消息或者NG建立响应(NG setup response)消息等，本申请实施例对此不做具体限定。
S1804a、第一RAN设备存储第一RAN设备支持的网络切片的切片映射信息。
S1802b、第二RAN设备向AMF网元发送N2消息3。相应的，AMF网元接收来自第二RAN设备的N2消息3。
其中，该N2消息3包括第二RAN设备的信息和第二RAN设备支持的切片信息列表(这里的切片信息列表也可以称为切片信息集合)。
可选的，本申请实施例中，第二RAN设备的信息可以包括第二RAN设备的标识或者第一RAN设备所在的TA等，本申请实施例对此不做具体限定。
可选的，本申请实施例中的N2消息3可以是N2连接请求(N2 connection request)消息或者NG建立请求(NG setup request)消息等，本申请实施例对此不做具体限定。
需要说明的是，本申请实施例以第二RAN设备与一个AMF网元交互为例进行说明。当然，若第二RAN设备与多个AMF网元之间存在N2接口(或NG接口)，则第二RAN设备需要向多个AMF网元分别发送上述N2消息3，本申请实施例对此不做具体限定。
示例性的，假设第二RAN设备支持的网络切片包括S-NSSAI-Y指示的网络切片和S-NSSAI-X指示的网络切片，则第二RAN设备支持的切片信息列表可以如表四所示：
表四
Figure PCTCN2020115959-appb-000004
S1803b、AMF网元向第二RAN设备发送N2消息4。相应的，第二RAN设备接收来自AMF网元的N2消息4。
其中，该N2消息4包括第二RAN设备支持的网络切片的切片映射信息。
示例性的，假设如表四所示，第二RAN设备支持的切片信息列表包括S-NSSAI-Y、S-NSSAI-X，S-NSSAI-X指示的网络切片与S-NSSAI-A指示的网络切片具有映射关系，S-NSSAI-Y指示的网络切片与S-NSSAI-B指示的网络切片具有映射关系，则第二RAN设备支持的网络切片的切片映射信息可以如表五所示：
表五
Figure PCTCN2020115959-appb-000005
类似的，或者，该N2消息2可包括AMF网元支持的网络切片的S-NSSAI，以及与每个AMF网元支持的网络切片具有映射关系的网络切片的S-NSSAI。例如，第二RAN设备收到如上述表一的切片映射信息。
可选的，本申请实施例中，该N2消息4还可以包括AMF网元支持的网络切片的S-NSSAI。
可选的，本申请实施例中的N2消息4可以是N2连接响应(N2 connection response)消息或者NG建立响应(NG setup response)消息等，本申请实施例对此不做具体限定。
S1804b、第二RAN设备存储第二RAN设备支持的网络切片的切片映射信息。
需要说明的是，本申请实施例分别以第一RAN设备从AMF网元获取第一RAN设备支持的网络切片的切片映射信息，以及第二RAN设备从AMF网元获取第二RAN设备支持的网络切片的切片映射信息为例进行说明。当然，若存在其它RAN设备与图 18中的AMF网元之间存在N2接口(或NG接口)，则其它RAN设备也可以通过上述步骤S1802a-S1803a的方式或者上述步骤S1802b-S1803b的方式获取该RAN设备支持的网络切片的切片映射信息，本申请实施例在此不再一一赘述。
S1805、终端设备注册到AMF网元上之后，发起会话建立流程。
其中，该会话建立流程的详细描述可参考现有技术，在此不再赘述。
通过注册流程，终端设备可以注册到AMF网元上。具体的，在注册流程中，终端设备可以向AMF网元发送注册请求消息，注册请求消息中携带请求的(requested)NSSAI。AMF网元接收到注册请求消息之后，根据终端设备的签约数据以及requested NSSAI确定允许的(allowed)NSSAI。allowed NSSAI包括至少一个S-NSSAI，allowed NSSAI包括的至少一个S-NSSAI为允许该终端设备接入的网络切片的标识，具体可以为允许该终端设备在当前注册区接入的网络切片的标识。
此外，本申请实施例中，终端设备注册到AMF网元上之后，可以建立一个或多个会话，本申请实施例对此不作具体限定。
进一步的，终端设备发生了移动，触发Xn接口的切换流程。具体地，当终端设备处于连接态时，终端设备根据第二RAN设备下发的测量配置消息进行相关测量，并将测量报告发送至第二RAN设备，其中，测量报告中包含了待切换至目标侧的候选RAN设备的信息列表(a list of candidate Target IDs)，以及每一个候选RAN设备与终端设备之间的测量指标的结果，测量指标包括终端设备获得的参考信号强度(reference signal strength indication，RSSI)、参考信号接收功率(reference signal receiving power，RSRP)、参考信号的接收质量(reference signal receiving quality，RSRQ)等中的至少一项。进而第二RAN设备根据终端设备上报的测量指标的结果从多个候选RAN设备中选出一个作为目标RAN设备(target RAN，T-RAN)(即下述第一RAN设备)，进一步地，第二RAN设备判断出与该第一RAN之间存在Xn接口，则触发Xn based切换流程，执行下述步骤S1806。
S1806、第二RAN设备向第一RAN设备发送切换请求(handover request)。相应的，第一RAN设备接收来自第二RAN设备的切换请求。
其中，该切换请求包括终端设备的各个会话关联的网络切片的S-NSSAI。
可选的，该切换请求还可以包括目标小区的标识信息或者终端设备的各个会话对应的QoS文件(profile(s))信息等，本申请实施例对此不作具体限定。
下面以终端设备的会话1为例进行说明。
S1807、第一RAN设备确定不支持终端设备的会话1关联的网络切片。
为方便下述说明，本申请实施例中，将终端设备的会话1关联的网络切片称之为网络切片1，在此统一说明，以下不再赘述。
其中，网络切片1的标识包含在步骤S1805中的allowed NSSAI中。本申请实施例中，第一RAN设备确定不支持网络切片1可以理解为，第一RAN设备确定第一RAN设备所在的TA不支持网络切片1，比如第一RAN设备所在的TA未部署网络切片1，终端设备移出了网络切片1的服务范围，在此统一说明，以下不再赘述。
S1808、第一RAN设备确定网络切片2。其中，第一RAN设备支持网络切片2，且网络切片2与网络切片1具有映射关系。
可选的，本申请实施例中，第一RAN设备确定网络切片2，包括：第一RAN设备根据网络切片1的S-NSSAI，以及网络切片1与网络切片2的映射信息，确定网络切片2。其中，网络切片1与网络切片2的映射信息可以是第一RAN设备在步骤S1804a中存储的。
可选的，本申请实施例中，若存在多个网络切片与网络切片1具有映射关系，则第一RAN设备可以选择AMF网元支持的网络切片作为网络切片2。
示例性的，假设网络切片1的S-NSSAI为S-NSSAI-X，第一RAN设备不支持网络切片1，但是第一RAN设备支持与S-NSSAI-X具有映射关系的S-NSSAI-A指示的网络切片，则第一RAN设备可以确定S-NSSAI-A指示的网络切片为网络切片2，进而第一RAN设备可以允许将会话1切换到第一RAN设备侧。
或者，示例性的，假设网络切片1的S-NSSAI为S-NSSAI-X，第一RAN设备不支持网络切片1，但是第一RAN设备支持与S-NSSAI-X具有映射关系的S-NSSAI-A和S-NSSAI-AA指示的网络切片，并且与第一RAN设备连接的AMF网元支持
S-NSSAI-A指示的网络切片，不支持S-NSSAI-AA指示的网络切片，则第一RAN设备可以确定S-NSSAI-A指示的网络切片为网络切片2，进而第一RAN设备可以允许将1会话1切换到第一RAN设备侧。
示例性的，第一RAN设备确定与第一RAN设备连接的AMF网元支持S-NSSAI-A指示的网络切片，不支持S-NSSAI-AA指示的网络切片的方法可以是：第一RAN设备根据步骤1802a获取的N2消息2中包括的AMF网元支持的网络切片的S-NSSAI确定AMF网元支持S-NSSAI-A指示的网络切片，不支持S-NSSAI-AA指示的网络切片。
S1809、第一RAN设备向AMF网元发送N2路径切换请求(N2 path switch request)。相应的，AMF网元接收来自第一RAN设备的N2路径切换请求。
其中，该N2路径切换请求包括终端设备的位置信息以及N2 SM信息。其中，N2SM信息包括会话1的标识，以及与会话1关联的网络切片1具有映射关系的网络切片2的S-NSSAI。
此外，该N2 SM信息中还可以包括第一指示信息，其中，第一指示信息用于指示该S-NSSAI是与会话1关联的网络切片1具有映射关系的网络切片2的标识。
S1810、AMF网元向SMF网元发送会话更新SM上下文请求(session update SM context request)。相应的，SMF网元接收来自AMF网元的会话更新SM上下文请求。
其中，该会话更新SM上下文请求包括上述N2 SM信息。
S1811、SMF网元确定网络切片2的S-NSSAI是否是终端设备的签约支持的S-NSSAI。
若SMF网元根据N2 SM信息中的第一指示信息确定N2 SM信息中包含的S-NSSAI是与会话1关联的网络切片1具有映射关系的网络切片2的标识，进一步地，SMF网元判断网络切片2的S-NSSAI是终端设备的签约支持的映射S-NSSAI，继续执行下述步骤S1812；否则，该切换流程结束。
S1812、SMF网元向UPF网元发送N4会话修改请求(N4 session modification request)。相应的，UPF网元接收来自SMF网元的N4会话修改请求。
S1813、UPF网元向SMF网元发送N4会话修改响应(N4 session modification  reqsponse)。相应的，SMF网元接收来自UPF网元的N4会话修改响应。
S1814、SMF网元向AMF网元发送会话更新SM上下文响应(session update SM context response)。相应的，AMF网元接收来自SMF网元的会话更新SM上下文响应。
S1815、AMF网元向第一RAN设备发送N2路径切换请求确认(N2 path switch request ACK)。相应的，第一RAN设备接收来自AMF网元的N2路径切换请求确认。
其中，上述步骤S1812-S1815的具体实现可参考现有技术，在此不再赘述。
需要说明的是，上述步骤S1807-S1815是以终端设备的一个会话(即会话1)的切换流程为例进行说明。若步骤S1806的切换请求中包括终端设备的多个会话关联的网络切片的NSSAI，则对于每个会话的切换流程均可参考上述步骤S1807-S1815，在此统一说明，以下不再赘述。
S1816、切换后，终端设备发起注册更新流程。
该过程中，终端设备向AMF网元发送注册请求消息，由于终端设备的会话关联的网络切片标识发生了变化，因此在注册更新流程中，AMF网元为终端设备确定new allowed NSSAI，并将new allowed NSSAI通过注册接受消息发送至终端设备。new allowed NSSAI包括至少一个S-NSSAI，new allowed NSSAI包括的至少一个S-NSSAI为允许该终端设备在目标RAN设备(即上述的第一RAN设备)的注册区接入的网络切片的标识。
其中，new allowed NSSAI包含网络切片2的标识。new allowed NSSAI可以是对前面步骤S1805中allowed NSSAI的更新，可以理解为，在切换前AMF网元为终端设备确定的allowed NSSAI包含网络切片1的标识，切换后，AMF网元为终端设备确定的new allowed NSSAI包含网络切片2的标识，而不包含网络切片1的标识。
移动性注册更新流程结束之后，SMF网元发起会话修改流程，在会话修改流程中，SMF网元向终端设备发送N1会话管理消息，该N1会话管理消息中包含终端设备的会话标识以及网络切片2的标识，用于更新终端设备上存储的终端设备的会话关联的网络切片，在此统一说明，以下不再赘述。
现有的Xn接口切换流程中，若第一RAN设备不支持终端设备的会话关联的网络切片(即上述网络切片1)，则拒绝终端设备的会话切换到目标侧，从而导致该会话无法在目标侧保持会话连续性，影响终端设备的业务体验。采用本申请实施例提供的网络切片选择的方法，即使第一RAN设备不支持网络切片1，由于第一RAN设备可以执行切片映射，确定出第一RAN设备支持的与终端设备的会话关联的网络切片具有映射关系的网络切片(即上述网络切片2)，并触发将终端设备的会话从网络切片1迁移到网络切片2，因此可以保持会话的连续性。
其中，上述步骤S1801至S1816中的第一RAN设备、第二RAN设备或者AMF网元的动作可以由图4所示的通信设备400中的处理器401调用存储器403中存储的应用程序代码来执行，本实施例对此不作任何限制。
可选的，以图14所示的通信系统应用于如图16所示的5G网络为例，如图19所示，为本申请实施例提供的另一种网络切片选择的方法，该网络切片选择的方法在注册流程中，AMF网元将slice mapping下发至第二RAN设备，由第二RAN设备本地保存。会话建立过程中，第二RAN设备可以基于slice mapping以及当前会话的 S-NSSAI确定出匹配的S-NSSAI(mapped S-NSSAI)。后续Xn切换过程中，第二RAN设备可以将与当前会话的S-NSSAI匹配的S-NSSAI发送给第一RAN设备，以便第一RAN设备确定是否支持与当前会话的S-NSSAI匹配的S-NSSAI指示的网络切片。具体的，图19所示的网络切片选择的方法包括如下步骤：
S1901、AMF网元获取第一映射关系列表，该第一映射关系列表包括AMF网元支持的每个网络切片的切片映射信息。
其中，步骤S1901的相关描述可参考图18所示的实施例的步骤S1801，在此不再赘述。
S1902、终端设备通过第二RAN设备连接到网络，并通过第二RAN设备向AMF网元发送注册请求。相应的，AMF网元接收来自终端设备的注册请求。
其中，该注册请求包括终端设备请求的NSSAI(requested NSSAI)。
S1903、AMF网元确定允许的NSSAI(allowed NSSAI)。
本申请实施例中，AMF网元可以根据终端设备的签约数据以及requested NSSAI确定allowed NSSAI，具体可参考现有的实现方式，在此不再赘述。
S1904、AMF网元确定第二映射关系列表，该第二映射关系列表包括allowed NSSAI指示的网络切片的切片映射信息。
示例性的，假设allowed NSSAI为S-NSSAI-X和S-NSSAI-Y，S-NSSAI-X指示的网络切片与S-NSSAI-A指示的网络切片具有映射关系，S-NSSAI-Y指示的网络切片与S-NSSAI-B指示的网络切片具有映射关系，则第二映射关系列表可以如表六所示：
表六
Figure PCTCN2020115959-appb-000006
可选的，本申请实施例中，AMF网元可以根据allowed NSSAI以及步骤S1901中AMF网元获取的第一映射关系列表，确定第二映射关系列表。其中，第一映射关系列表中包括第二映射关系列表。
需要说明的是，本申请实施例中的映射关系列表也可以称之为映射关系集合，本申请实施例对此不做具体限定。
S1905、AMF网元向第二RAN设备发送N2消息1。相应的，第二RAN设备接收来自AMF网元的N2消息1。
其中，N2消息1包括上述allowed NSSAI、第二映射关系列表和注册接受(registration accept)消息。
S1906、第二RAN设备存储第二映射关系列表。
S1907、第二RAN设备向终端设备发送注册接受消息。相应的，终端设备接收来自第二RAN设备的注册接受消息。
S1908、终端设备向AMF网元发送会话建立请求。相应的，AMF网元接收来自终端设备的会话建立请求。
其中，该会话建立请求包括终端设备的会话1的标识，会话1关联的网络切片的S-NSSAI和DNN等参数，具体可参考现有技术，在此不再赘述。此外，会话1关联的网络切片的S-NSSAI包含在步骤S1903中的allowed NSSAI中。
为方便下述说明，本申请实施例中，将终端设备的会话1关联的网络切片称之为网络切片1，在此统一说明，以下不再赘述。
S1909、AMF网元选择SMF网元，并触发SMF网元在核心网侧创建会话上下文，相关实现可参考现有技术，在此不予赘述。
S1910、AMF网元向第二RAN设备发送N2会话请求(N2 session request)。相应的，第二RAN设备接收来自AMF网元的N2会话请求。
其中，N2会话请求包括N2 SM information，N2 SM information包括会话1的标识以及会话1关联的网络切片1的S-NSSAI。
S1911、第二RAN设备确定与网络切片1具有映射关系的网络切片的S-NSSAI。
其中，第二RAN设备可以根据会话1关联的网络切片1的S-NSSAI，以及步骤S1906存储的第二映射关系，确定与网络切片1具有映射关系的网络切片的S-NSSAI。
需要说明的是，步骤S1908-S1911以终端设备的一个会话(即会话1)的建立流程为例进行说明。当然，终端设备可能建立多个会话，每个会话的建立流程均可参考上述步骤S1908-S1911，在此不再赘述。
进一步的，终端设备发生了移动，触发Xn接口的切换流程。具体地，当终端设备处于连接态时，终端设备根据第二RAN设备下发的测量配置消息进行相关测量，并将测量报告发送至第二RAN设备，其中，测量报告中包含了待切换至目标侧的候选RAN设备的信息列表(a list of candidate Target IDs)，以及每一个候选RAN设备与终端设备之间的测量指标的结果，测量指标包括终端设备获得的RSSI、RSRP、或者RSRQ等。进而第二RAN设备根据终端设备上报的测量指标的结果从多个候选RAN设备中选出一个作为目标RAN设备(target RAN，T-RAN)(即下述第一RAN设备)，进一步地，第二RAN设备判断出与该第一RAN之间存在Xn接口，则触发Xn based切换流程，执行下述步骤S1912。
S1912、第二RAN设备向第一RAN设备发送切换请求(handover request)。相应的，第一RAN设备接收来自第二RAN设备的切换请求。
其中，该切换请求包括终端设备的各个会话关联的网络切片的S-NSSAI(例如网络切片1的S-NSSAI)以及与各个会话关联的网络切片具有映射关系的网络切片的S-NSSAI(例如，与网络切片1具有映射关系的网络切片的S-NSSAI)。
可选的，该切换请求中还可以包括第一指示信息和第二指示信息中的至少一项，其中，第一指示信息用于指示哪些S-NSSAI是与会话关联的网络切片，第二指示信息用于指示哪些S-NSSAI是与会话关联的网络切片具有映射关系的网络切片，本申请实施例对此不作具体限定。
可选的，该切换请求还可以包括目标小区的标识信息或者终端设备的各个会话对应的QoS文件(profile(s))信息等，本申请实施例对此不作具体限定。
下面以终端设备的会话1为例进行说明。
S1913、第一RAN设备确定不支持终端设备的会话1关联的网络切片1，支持与 网络切片1具有映射关系的网络切片。
作为一种实现方式，若步骤S1912中，第一RAN设备从第二RAN设备接收了第一指示信息以及第二指示信息，则第一RAN设备可以根据第一指示信息优先判断是否支持终端设备的会话1关联的网络切片1，如果第一RAN设备确定不支持终端设备的会话1关联的网络切片1，则第一RAN设备根据第二指示信息判断是否支持与网络切片1具有映射关系的网络切片。
作为另一种实现方式，若步骤S1912中，第一RAN设备从第二RAN设备接收了第一指示信息或者第二指示信息，则第一RAN设备可以根据第一指示信息或者第二指示信息，获知哪些S-NSSAI是与会话关联的网络切片，哪些S-NSSAI是与会话关联的网络切片具有映射关系的网络切片，进而第一RAN设备可以确定是否支持终端设备的会话1关联的网络切片1。如果第一RAN设备确定不支持终端设备的会话1关联的网络切片1，则第一RAN设备可以继续确定是否支持与网络切片1具有映射关系的网络切片。
作为又一种实现方式，若步骤S1912中，第一RAN设备未从第二RAN设备接收第一指示信息和第二指示信息，则第一RAN设备可以根据第二RAN设备发送的所有网络切片的S-NSSAI进行判断该第一RAN设备是否支持其中至少一个S-NSSAI，本申请实施例对此不做具体限定。
S1914、第一RAN设备向AMF网元发送N2路径切换请求(N2 path switch request)。相应的，AMF网元接收来自第一RAN设备的N2路径切换请求。
其中，该N2路径切换请求包括终端设备的位置信息以及N2 SM信息。其中，N2SM信息包括会话1的标识，以及与会话1关联的网络切片1具有映射关系的网络切片2的S-NSSAI。
此外，该N2 SM信息中还可以包括第三指示信息，其中，第三指示信息用于指示该S-NSSAI是与会话1关联的网络切片1具有映射关系的网络切片2的标识。可选的，本申请实施例中，若第一RAN设备支持的网络切片中存在多个网络切片与网络切片1具有映射关系，则第一RAN设备可以选择AMF网元支持的网络切片作为网络切片2。
S1915、AMF网元向SMF网元发送会话更新SM上下文请求(session update SM context request)。相应的，SMF网元接收来自AMF网元的会话更新SM上下文请求。
其中，该会话更新SM上下文请求包括上述N2 SM信息。
SMF网元确定网络切片2的S-NSSAI是否是终端设备的签约支持的S-NSSAI。
若SMF网元根据N2 SM信息中的第三指示信息确定N2 SM信息中包含的S-NSSAI是与会话1关联的网络切片1具有映射关系的网络切片2的标识，进一步地，SMF网元判断网络切片2的S-NSSAI是终端设备的签约支持的映射S-NSSAI，继续执行下述步骤S1916；否则，该切换流程结束。
S1916-S1920、同图18所示的实施例中的步骤S1812-S1816，相关描述可参考图18所示的实施例，在此不再赘述。
需要说明的是，上述步骤S1913-S1919是以终端设备的一个会话(即会话1)的切换流程为例进行说明。若步骤S1912的切换请求中包括终端设备的多个会话关联的网络切片的NSSAI，则对于每个会话的切换流程均可参考上述步骤S1913-S1919，在 此统一说明，以下不再赘述。
现有的Xn接口切换流程中，若第一RAN设备不支持终端设备的会话关联的网络切片(即上述网络切片1)，则拒绝终端设备的会话切换到目标侧，从而导致该会话无法在目标侧保持会话连续性，影响终端设备的业务体验。采用本申请实施例提供的网络切片选择的方法，即使第一RAN设备不支持网络切片1，由于第二RAN设备可以执行切片映射，确定出与网络切片1具有映射关系的网络切片，并且将与网络切片1具有映射关系的网络切片的S-NSSAI发送给第一RAN设备，使得第一RAN设备在支持与网络切片1具有映射关系的网络切片的情况下，触发将终端设备的会话从网络切片1迁移到第一RAN设备支持的与网络切片1具有映射关系的网络切片(如上述网络切片2)上，因此可以保持会话的连续性。
其中，上述步骤S1901至S1920中的第一RAN设备、第二RAN设备或者AMF网元的动作可以由图4所示的通信设备400中的处理器401调用存储器403中存储的应用程序代码来执行，本实施例对此不作任何限制。
可选的，以图14所示的通信系统应用于如图16所示的5G网络为例，如图20所示，为本申请实施例提供的另一种网络切片选择的方法，该网络切片选择的方法在会话建立流程中，AMF网元将slice mapping下发至第二RAN设备，由第二RAN设备本地保存。后续Xn切换过程中，第二RAN设备可以将slice mapping发送给第一RAN设备，以便第一RAN设备确定是否支持与终端设备的会话关联的网络切片具有映射关系的网络切片。具体的，图20所示的网络切片选择的方法包括如下步骤：
S2001、终端设备通过注册流程，成功注册到AMF网元上。
S2002、终端设备向AMF网元发送会话建立请求。相应的，AMF网元接收来自终端设备的会话建立请求。
其中，该会话建立请求包括终端设备的会话1的标识，会话1关联的网络切片的S-NSSAI和DNN等参数，具体可参考现有技术，在此不再赘述。
为方便下述说明，本申请实施例中，将终端设备的会话1关联的网络切片称之为网络切片1，在此统一说明，以下不再赘述。
S2003、AMF网元选择SMF网元，并触发SMF网元在核心网侧创建会话上下文，相关实现可参考现有技术，在此不予赘述。
S2004、AMF网元获取与网络切片1具有映射关系的网络切片的S-NSSAI。
一种可能的实现方式中，AMF网元可以预先获取图18所示的实施例中的第一映射关系列表，此时，AMF网元可以根据网络切片1的S-NSSAI以及该第一映射关系列表，确定与网络切片1具有映射关系的网络切片的S-NSSAI。
另一种可能的实现方式中，AMF网元未预先获取图18所示的实施例中的第一映射关系列表，此时，AMF网元可以从NSSF网元获取网络切片1具有映射关系的网络切片的S-NSSAI。具体的，AMF网元可以向NSSF网元发送切片映射请求(slice mapping request)，该切片映射请求包括网络切片1的S-NSSAI。进而，NSSF网元可以确定与网络切片1具有映射关系的网络切片的S-NSSAI，并向AMF网元发送切片映射响应(slice mapping response)，该切片映射响应包括与网络切片1具有映射关系的网络切片的S-NSSAI。
S2005、AMF网元向第二RAN设备发送N2会话请求(N2 session request)。相应的，第二RAN设备接收来自AMF网元的N2会话请求。
其中，N2会话请求包括N2 SM information，N2 SM information包括会话1的标识、会话1关联的网络切片1的S-NSSAI以及与网络切片1具有映射关系的网络切片的S-NSSAI。
其中，第二RAN设备获取会话1关联的网络切片1的S-NSSAI以及与网络切片1具有映射关系的网络切片的S-NSSAI之后，可以存储会话1关联的网络切片1的S-NSSAI以及与网络切片1具有映射关系的网络切片的S-NSSAI，本申请实施例对此不做具体限定。
需要说明的是，步骤S2002-S2005以终端设备的一个会话(即会话1)的建立流程为例进行说明。当然，终端设备可能建立多个会话，每个会话的建立流程均可参考上述步骤S2002-S2005，在此不再赘述。
进一步的，终端设备发生了移动，触发Xn接口的切换流程。具体地，当终端设备处于连接态时，终端设备根据第二RAN设备下发的测量配置消息进行相关测量，并将测量报告发送至第二RAN设备，其中，测量报告中包含了待切换至目标侧的候选RAN设备的信息列表(a list of candidate Target IDs)，以及每一个候选RAN设备与终端设备之间的测量指标的结果，测量指标包括终端设备获得的RSSI、RSRP、或者RSRQ等。进而第二RAN设备根据终端设备上报的测量指标的结果从多个候选RAN设备中选出一个作为目标RAN设备(target RAN，T-RAN)(即下述第一RAN设备)，进一步地，第二RAN设备判断出与该第一RAN之间存在Xn接口，则触发Xn based切换流程，执行下述步骤S2006。
S2006-S2014、同图19所示的实施例中的步骤S1912-S1920，相关描述可参考图19所示的实施例，在此不再赘述。
现有的Xn接口切换流程中，若第一RAN设备不支持终端设备的会话关联的网络切片(即上述网络切片1)，则拒绝终端设备的会话切换到目标侧，从而导致该会话无法在目标侧保持会话连续性，影响终端设备的业务体验。采用本申请实施例提供的网络切片选择的方法，即使第一RAN设备不支持网络切片1，由于AMF网元可以执行切片映射，确定出与网络切片1具有映射关系的网络切片，并且将与网络切片1具有映射关系的网络切片的S-NSSAI发送给第二RAN设备，由第二RAN设备发送给第一RAN设备，使得第一RAN设备在支持与网络切片1具有映射关系的网络切片的情况下，触发将终端设备的会话从网络切片1迁移到第一RAN设备支持的与网络切片1具有映射关系的网络切片(如上述网络切片2)上，因此可以保持会话的连续性。
其中，上述步骤S2001至S2014中的第一RAN设备、第二RAN设备或者AMF网元的动作可以由图4所示的通信设备400中的处理器401调用存储器403中存储的应用程序代码来执行，本实施例对此不作任何限制。
上述图18至图20以具体实施例的方式给出了几种网络切片选择的方法。如图21所示，为本申请实施例提供的一种网络切片选择的方法，该方法包括如下步骤：
S2101、第一接入网设备接收来自第二接入网设备的第一网络切片的信息，其中，第一网络切片为终端设备的会话关联的网络切片。
示例性的，本申请实施例中的第一接入网设备例如可以为图18所示的实施例中的第一RAN设备，第二接入网设备例如可以为图18所示的实施例中的第二RAN设备。
可选的，本申请实施例中的网络切片的信息例如可以为网络切片的S-NSSAI。
S2102、第一接入网设备确定第一接入网设备不支持第一网络切片。
S2103、第一接入网设备确定第二网络切片，其中，第一接入网设备支持第二网络切片，且第二网络切片与第一网络切片具有映射关系。
可选的，本申请实施例中，第二网络切片与第一网络切片具有映射关系，包括：第一网络切片和第二网络切片能够提供相同的业务类型；或者，第一网络切片和第二网络切片能够共享网络切片实例。
可选的，本申请实施例中，第一接入网设备确定第二网络切片，包括：第一接入网设备根据第一网络切片的信息，以及第二网络切片与第一网络切片的映射信息，确定第二网络切片。
S2104、第一接入网设备向会话管理网元发送指示信息，该指示信息用于指示第二网络切片能够服务该会话。
示例性的，该指示信息例如可以为终端设备的会话标识以及第二网络切片的S-NSSAI。
其中，结合具体场景，步骤S2101-S2104的一种可能实现方式可参考上述图18所示的实施例中的步骤S1806-S1810，在此不再赘述。
可选的，本申请实施例中，该网络切片选择的方法还可以包括：第一接入网设备向移动性管理网元发送第二网络切片的信息，第一接入网设备接收来自移动性管理网元的第二网络切片与第一网络切片的映射信息。其中，该方案的一种可能实现方式可参考上述图18所示的实施例中的步骤S1802a-S1803a，在此不再赘述。
现有的Xn接口切换流程中，若第一接入网设备不支持终端设备的会话关联的网络切片，则拒绝终端设备的会话切换到目标侧，从而导致该会话无法在目标侧保持会话连续性，影响终端设备的业务体验。采用本申请实施例提供的网络切片选择的方法，即使第一接入网设备不支持终端设备的会话关联的网络切片，由于第一接入网设备可以执行切片映射，确定出第一接入网设备支持的与第一网络切片具有映射关系的第二网络切片，因此可以触发将终端设备的会话从第一网络切片迁移到第二网络切片，进而可以保持会话的连续性。
其中，上述步骤S2101至S2104中的第一接入网设备的动作可以由图4所示的通信设备400中的处理器401调用存储器403中存储的应用程序代码来执行，本实施例对此不作任何限制。
可选的，如图22所示，为本申请实施例提供的一种网络切片选择的方法，该方法包括如下步骤：
S2201、第二接入网设备确定第一网络切片的信息和第二网络切片的信息，其中，第一网络切片为终端设备的会话关联的网络切片，第二网络切片与第一网络切片具有映射关系。
示例性的，本申请实施例中的第一接入网设备例如可以为图19或图20所示的实施例中的第一RAN设备，第二接入网设备例如可以为图19或图20所示的实施例中的 第二RAN设备。
可选的，本申请实施例中的网络切片的信息例如可以为网络切片的S-NSSAI。
可选的，本申请实施例中，第二网络切片与第一网络切片具有映射关系，包括：第一网络切片和第二网络切片能够提供相同的业务类型；或者，第一网络切片和第二网络切片能够共享网络切片实例。
一种可能的实现方式中，本申请实施例中，第二接入网设备确定第一网络切片的信息和第二网络切片的信息，包括：第二接入网设备接收来自移动性管理网元的第二网络切片的信息和第一网络切片的信息。
另一种可能的实现方式中，本申请实施例中，第二接入网设备确定第一网络切片的信息和第二网络切片的信息，包括：第二接入网设备接收来自移动性管理网元的第一网络切片的信息；第二接入网设备根据第一网络切片的信息，以及第二网络切片与第一网络切片的映射信息，确定第二网络切片的信息。
可选的，本申请实施例中的第一网络切片可以为终端设备允许的NSSAI所指示的网络切片中的网络切片，本申请实施例提供的网络切片选择的方法还可以包括：第二接入网设备接收来自移动性管理网元的上述映射信息。其中，该方案的一种可能实现方式可参考上述图19所示的实施例中的步骤S1905，在此不再赘述。
S2202、第二接入网设备向第一接入网设备发送第一网络切片的信息和第二网络切片的信息。
其中，步骤S2202的一种可能实现方式可参考上述图19所示的实施例中的步骤S1912或者可参考上述图20所示的实施例中的步骤S2006，在此不再赘述。
其中，结合具体场景，步骤S2201-S2202的一种可能实现方式可参考上述图19所示的实施例中的步骤S1910-S1912；或者，结合具体场景，步骤S2201-S2202的另一种可能实现方式可参考上述图20所示的实施例中的步骤S2005-S2006，在此不再赘述。
现有的Xn接口切换流程中，若第一接入网设备不支持终端设备的会话关联的网络切片，则拒绝终端设备的会话切换到目标侧，从而导致该会话无法在目标侧保持会话连续性，影响终端设备的业务体验。采用本申请实施例提供的网络切片选择的方法，即使第一接入网设备不支持终端设备的会话关联的网络切片，由于第二接入网设备可以向第一接入网设备发送第一网络切片的信息和第一接入网设备支持的与第一网络切片具有映射关系的第二网络切片的信息，使得第一接入网设备可以获取第一网络切片的信息和第二网络切片的信息，进而可以触发将终端设备的会话从第一网络切片迁移到第二网络切片，因此可以保持会话的连续性。
其中，上述步骤S2201至S2202中的第二接入网设备的动作可以由图4所示的通信设备400中的处理器401调用存储器403中存储的应用程序代码来执行，本实施例对此不作任何限制。
可选的，如图23所示，为本申请实施例提供的一种网络切片选择的方法，该方法包括如下步骤：
S2301、第一接入网设备接收来自第二接入网设备的第一网络切片的信息和第二网络切片的信息，其中，第一网络切片为终端设备的会话关联的网络切片，第二网络切片与第一网络切片具有映射关系。
示例性的，本申请实施例中的第一接入网设备例如可以为图19或图20所示的实施例中的第一RAN设备，第二接入网设备例如可以为图19或图20所示的实施例中的第二RAN设备。
可选的，本申请实施例中的网络切片的信息例如可以为网络切片的S-NSSAI。
可选的，本申请实施例中，第二网络切片与第一网络切片具有映射关系，包括：第一网络切片和第二网络切片能够提供相同的业务类型；或者，第一网络切片和第二网络切片能够共享网络切片实例。
其中，步骤S2301的一种可能实现方式可参考上述图19所示的实施例中的步骤S1912或者可参考上述图20所示的实施例中的步骤S2006，在此不再赘述。
S2302、第一接入网设备确定第一接入网设备不支持第一网络切片，支持第二网络切片。
其中，步骤S2302的一种可能实现方式可参考上述图19所示的实施例中的步骤S1913或者可参考上述图20所示的实施例中的步骤S2007，在此不再赘述。
S2303、第一接入网设备向会话管理网元发送指示信息，该指示信息用于指示第二网络切片能够服务该会话。
示例性的，该指示信息例如可以为终端设备的会话标识以及第二网络切片的S-NSSAI。
其中，结合具体场景，步骤S2301-S2303的一种可能实现方式可参考上述图19所示的实施例中的步骤S1912-S1914；或者，结合具体场景，步骤S2301-S2303的另一种可能实现方式可参考上述图20所示的实施例中的步骤S2006-S2008，在此不再赘述。
现有的Xn接口切换流程中，若第一接入网设备不支持终端设备的会话关联的网络切片，则拒绝终端设备的会话切换到目标侧，从而导致该会话无法在目标侧保持会话连续性，影响终端设备的业务体验。采用本申请实施例提供的网络切片选择的方法，即使第一接入网设备不支持终端设备的会话关联的网络切片，由于第一接入网设备可以获取第一网络切片的信息和第一接入网设备支持的与第一网络切片具有映射关系的第二网络切片的信息，并且可以触发将终端设备的会话从第一网络切片迁移到第二网络切片，因此可以保持会话的连续性。
其中，上述步骤S2301至S2303中的第一接入网设备的动作可以由图4所示的通信设备400中的处理器401调用存储器403中存储的应用程序代码来执行，本实施例对此不作任何限制。
可选的，如图24所示，为本申请实施例提供的一种网络切片选择的方法，该方法包括如下步骤：
S2401、移动性管理网元确定第一网络切片的信息和第二网络切片的信息，其中，第二网络切片与第一网络切片具有映射关系。
可选的，本申请实施例中的网络切片的信息例如可以为网络切片的S-NSSAI。
可选的，本申请实施例中，第二网络切片与第一网络切片具有映射关系，包括：第一网络切片和第二网络切片能够提供相同的业务类型；或者，第一网络切片和第二网络切片能够共享网络切片实例。
可选的，本申请实施例中，移动性管理网元确定第一网络切片的信息和第二网络 切片的信息，包括：移动性管理网元确定第一网络切片的信息；移动性管理网元根据第一网络切片的信息，以及第二网络切片与第一网络切片的映射信息，确定第二网络切片的信息。
S2402、移动性管理网元向接入网设备发送第一网络切片与第二网络切片的映射信息。
一种可能的实现方式中，第一网络切片为接入网设备支持的网络切片。结合具体场景，步骤S2401-S2402的一种可能实现方式可参考上述图18所示的实施例中的步骤S1802a-S1803a或者上述图18所示的实施例中的步骤S1802b-S1803b，在此不再赘述。
另一种可能的实现方式中，第一网络切片为终端设备的会话关联的网络切片。结合具体场景，步骤S2401-S2402的一种可能实现方式可参考上述图20所示的实施例中的步骤S2004-S2005，在此不再赘述。
又一种可能的实现方式中，第一网络切片为终端设备允许的NSSAI所指示的网络切片。结合具体场景，步骤S2401-S2402的一种可能实现方式可参考上述图19所示的实施例中的步骤S1903-S1905，在此不再赘述。
现有的Xn接口切换流程中，若第一接入网设备不支持终端设备的会话关联的网络切片，则拒绝终端设备的会话切换到目标侧，从而导致该会话无法在目标侧保持会话连续性，影响终端设备的业务体验。采用本申请实施例提供的网络切片选择的方法，即使第一接入网设备不支持终端设备的会话关联的网络切片，由于第一接入网设备可以获取第一网络切片的信息和第一接入网设备支持的与第一网络切片具有映射关系的第二网络切片的信息，因此可以触发将终端设备的会话从第一网络切片迁移到第二网络切片，进而可以保持会话的连续性。
其中，上述步骤S2401至S2402中的移动性管理网元的动作可以由图4所示的通信设备400中的处理器401调用存储器403中存储的应用程序代码来执行，本实施例对此不作任何限制。
可以理解的是，以上各个实施例中，由移动性管理网元实现的方法和/或步骤，也可以由可用于移动性管理网元的部件(例如芯片或者电路)实现；由第一接入网设备实现的方法和/或步骤，也可以由可用于第一接入网设备的部件(例如芯片或者电路)实现；由第二接入网设备实现的方法和/或步骤，也可以由可用于第二接入网设备的部件(例如芯片或者电路)实现。
上述主要从各个网元之间交互的角度对本申请实施例提供的方案进行了介绍。相应的，本申请实施例还提供了通信装置，该通信装置可以为上述方法实施例中的移动性管理网元，或者包含上述移动性管理网元的装置，或者为可用于移动性管理网元的部件；或者，该通信装置可以为上述方法实施例中的第一接入网设备，或者包含上述第一接入网设备的装置，或者为可用于第一接入网设备的部件；或者，该通信装置可以为上述方法实施例中的第二接入网设备，或者包含上述第二接入网设备的装置，或者为可用于第二接入网设备的部件。可以理解的是，该通信装置为了实现上述功能，其包含了执行各个功能相应的硬件结构和/或软件模块。本领域技术人员应该很容易意识到，结合本文中所公开的实施例描述的各示例的单元及算法步骤，本申请能够以硬件或硬件和计算机软件的结合形式来实现。某个功能究竟以硬件还是计算机软件驱动 硬件的方式来执行，取决于技术方案的特定应用和设计约束条件。专业技术人员可以对每个特定的应用来使用不同方法来实现所描述的功能，但是这种实现不应认为超出本申请的范围。
比如，以通信装置为上述方法实施例中的移动性管理网元为例，图12示出了一种移动性管理网元120的结构示意图。该移动性管理网元120包括收发模块1201和处理模块1202。所述收发模块1201，也可以称为收发单元用以实现收发功能，例如可以是收发电路，收发机，收发器或者通信接口。
其中，处理模块1202，用于确定终端设备的拜访地网络中的第一网络切片能够服务终端设备的第一会话；处理模块1202，还用于通过收发模块1201触发第一会话从第二网络切片迁移到第一网络切片，其中，第二网络切片为第一会话在拜访地网络当前关联的网络切片。
可选的，处理模块1202，用于确定终端设备的拜访地网络中的第一网络切片能够服务终端设备的第一会话，包括：用于确定终端设备移出了第二网络切片的服务范围，且终端设备当前位于第一网络切片的服务范围内；其中，第一网络切片与第三网络切片具有映射关系，第三网络切片为第一会话在终端设备的归属地网络关联的网络切片。
可选的，收发模块1201，还用于向第一会话管理网元发送第一指示信息，第一指示信息用于指示第一会话管理网元发起第一会话的修改流程；收发模块1201，还用于接收来自第一会话管理网元的第一信息和第二信息，其中，第一信息包括第一会话的标识和第一网络切片的S-NSSAI，第二信息包括第一会话的标识、第一网络切片的
S-NSSAI和第三网络切片的S-NSSAI；收发模块1201，还用于向第一接入网设备发送第一信息；以及，向终端设备发送第二信息，其中，第一信息和第二信息用于更新第一会话在拜访地网络对应的S-NSSAI。
可选的，处理模块1202，用于确定终端设备的拜访地网络中的第一网络切片能够服务终端设备的第一会话，包括：用于通过收发模块1201接收来自第一接入网设备的第二指示信息，第二指示信息用于指示第一接入网设备支持的第一网络切片能够服务第一会话。
可选的，处理模块1202，还用于确定第一会话在拜访地网络与除第二网络切片之外的其他网络切片关联，其中，其他网络切片与第三网络切片具有映射关系，且其他网络切片包括第一网络切片，第三网络切片为第一会话在终端设备的归属地网络关联的网络切片；收发模块1201，还用于向第二接入网设备发送其他网络切片的单网络切片选择辅助信息S-NSSAI，其中，第二接入网设备为支持第二网络切片的接入网设备。
可选的，收发模块1201，还用于向终端设备发送第三指示信息，第三指示信息用于指示终端设备发起第一会话关联的业务请求流程，业务请求流程用于建立第一会话的空口资源，其中，空口资源与第一网络切片关联。
可选的，收发模块1201，还用于向第一会话管理网元发送第一消息，第一消息用于请求第一会话管理网元建立第一会话的空口资源，其中，空口资源与第一网络切片关联。
可选的，收发模块1201，还用于向终端设备发送与第一会话的标识对应的第一网络切片的S-NSSAI和第三网络切片的S-NSSAI，第三网络切片为第一会话在终端设备 的归属地网络关联的网络切片。
可选的，处理模块1202，用于通过收发模块1201触发第一会话从第二网络切片迁移到第一网络切片，包括：用于通过收发模块1201向第一会话管理网元发送第二消息，第二消息用于请求第一用户面网元与第三用户面网元之间的用户面资源的建立，其中，第一会话管理网元为第一网络切片中服务第一会话的会话管理网元，第一用户面网元为第一网络切片中服务第一会话的用户面网元，第三用户面网元为第三网络切片中服务第一会话的用户面网元，第三网络切片为第一会话在终端设备的归属地网络关联的网络切片。
可选的，处理模块1202，用于通过收发模块1201触发第一会话从第二网络切片迁移到第一网络切片，包括：用于获取第一会话在第三网络切片的上下文信息，第三网络切片为第一会话在终端设备的归属地网络关联的网络切片；通过收发模块1201向第一会话管理网元发送第三消息，第三消息包括第一会话在第三网络切片的上下文信息，第三消息用于请求第一用户面网元与第三用户面网元之间的用户面资源的建立，其中，第一会话管理网元为第一网络切片中服务第一会话的会话管理网元，第一用户面网元为第一网络切片中服务第一会话的用户面网元，第三用户面网元为第三网络切片中服务第一会话的用户面网元。
可选的，处理模块1202，用于获取第一会话在第三网络切片的上下文信息，包括：用于通过收发模块1201向第二会话管理网元发送第四消息，第四消息用于请求第一会话在第三网络切片的上下文信息，第二会话管理网元为第二网络切片中服务第一会话的会话管理网元；通过收发模块1201接收来自第二会话管理网元的第一会话在第三网络切片的上下文信息。
可选的，收发模块1201，还用于向终端设备发送更新后的允许的NSSAI、以及第一网络切片的S-NSSAI和第三网络切片的S-NSSAI的映射关系，其中，更新后的允许的NSSAI中包括第一网络切片的S-NSSAI，第三网络切片为第一会话在终端设备的归属地网络关联的网络切片。
另一种可能的实现方式中：
处理模块1202，用于确定第一网络切片的信息和第二网络切片的信息，其中，第二网络切片与第一网络切片具有映射关系。收发模块1201，用于向接入网设备发送第一网络切片与第二网络切片的映射信息。
可选的，处理模块1202具体用于：确定第一网络切片的信息；根据第一网络切片的信息，以及第二网络切片与第一网络切片的映射信息，确定第二网络切片的信息。
可选的，第一网络切片为接入网设备支持的网络切片；或者，第一网络切片为终端设备的会话关联的网络切片；或者，第一网络切片为终端设备允许的NSSAI所指示的网络切片。
其中，上述方法实施例涉及的各步骤的所有相关内容均可以援引到对应功能模块的功能描述，在此不再赘述。
在本实施例中，该移动性管理网元120以采用集成的方式划分各个功能模块的形式来呈现。这里的“模块”可以指特定ASIC，电路，执行一个或多个软件或固件程序的处理器和存储器，集成逻辑电路，和/或其他可以提供上述功能的器件。在一个简单的 实施例中，本领域的技术人员可以想到该移动性管理网元120可以采用图4所示的通信设备400的形式。
比如，图4所示的通信设备400中的处理器401可以通过调用存储器403中存储的计算机执行指令，使得通信设备400执行上述方法实施例中的网络切片选择的方法。
具体的，图12中的收发模块1201和处理模块1202的功能/实现过程可以通过图4所示的通信设备400中的处理器401调用存储器403中存储的计算机执行指令来实现。或者，图12中的处理模块1202的功能/实现过程可以通过图4所示的通信设备400中的处理器401调用存储器403中存储的计算机执行指令来实现，图12中的收发模块1201的功能/实现过程可以通过图4中所示的通信设备400中的通信接口404来实现。
由于本实施例提供的移动性管理网元120可执行上述的网络切片选择的方法，因此其所能获得的技术效果可参考上述方法实施例，在此不再赘述。
比如，以通信装置为上述方法实施例中的第一接入网设备为例，图13示出了一种第一接入网设备130的结构示意图。该第一接入网设备130包括收发模块1301和处理模块1302。所述收发模块1301，也可以称为收发单元用以实现收发功能，例如可以是收发电路，收发机，收发器或者通信接口。
其中，收发模块1301，用于接收来自第二接入网设备的第一网络切片的S-NSSAI和第二网络切片的S-NSSAI，其中，第一网络切片和第二网络切片是终端设备的第一会话在终端设备的拜访地网络与第三网络切片具有映射关系的网络切片，且第二网络切片为第一会话在拜访地网络当前关联的网络切片，第三网络切片为第一会话在终端设备的归属地网络关联的网络切片；处理模块1302，用于确定不支持第二网络切片，支持第一网络切片；收发模块1301，还用于向移动性管理网元发送第二指示信息，第二指示信息用于指示第一网络切片能够服务第一会话。
另一种可能的实现方式中：
收发模块1301，用于接收来自第二接入网设备的第一网络切片的信息，其中，第一网络切片为终端设备的会话关联的网络切片。处理模块1302，用于确定第一接入网设备不支持第一网络切片。处理模块1302，还用于确定第二网络切片，其中，第一接入网设备支持第二网络切片，且第二网络切片与第一网络切片具有映射关系。收发模块1301，还用于向会话管理网元发送指示信息，指示信息用于指示第二网络切片能够服务该会话。
可选的，处理模块1302用于确定第二网络切片，包括：用于根据第一网络切片的信息，以及第二网络切片与第一网络切片的映射信息，确定第二网络切片。
可选的，收发模块1301，还用于向移动性管理网元发送第二网络切片的信息。收发模块1301，还用于接收来自移动性管理网元的第二网络切片与第一网络切片的映射信息。
又一种可能的实现方式中：
收发模块1301，用于接收来自第二接入网设备的第一网络切片的信息和第二网络切片的信息，其中，第一网络切片为终端设备的会话关联的网络切片，第二网络切片与第一网络切片具有映射关系。处理模块1302，用于确定第一接入网设备不支持第一网络切片，支持第二网络切片。收发模块1301，还用于向会话管理网元发送指示信息， 该指示信息用于指示第二网络切片能够服务该会话。
其中，上述方法实施例涉及的各步骤的所有相关内容均可以援引到对应功能模块的功能描述，在此不再赘述。
在本实施例中，该第一接入网设备130以采用集成的方式划分各个功能模块的形式来呈现。这里的“模块”可以指特定ASIC，电路，执行一个或多个软件或固件程序的处理器和存储器，集成逻辑电路，和/或其他可以提供上述功能的器件。在一个简单的实施例中，本领域的技术人员可以想到该第一接入网设备130可以采用图4所示的通信设备400的形式。
比如，图4所示的通信设备400中的处理器401可以通过调用存储器403中存储的计算机执行指令，使得通信设备400执行上述方法实施例中的网络切片选择的方法。
具体的，图13中的收发模块1301和处理模块1302的功能/实现过程可以通过图4所示的通信设备400中的处理器401调用存储器403中存储的计算机执行指令来实现。或者，图13中的处理模块1302的功能/实现过程可以通过图4所示的通信设备400中的处理器401调用存储器403中存储的计算机执行指令来实现，图13中的收发模块1301的功能/实现过程可以通过图4中所示的通信设备400中的通信接口404来实现。
由于本实施例提供的第一接入网设备130可执行上述的网络切片选择的方法，因此其所能获得的技术效果可参考上述方法实施例，在此不再赘述。
比如，以通信装置为上述方法实施例中的第二接入网设备为例，图25示出了一种第二接入网设备250的结构示意图。该第二接入网设备250包括收发模块2501和处理模块2502。所述收发模块2501，也可以称为收发单元用以实现收发功能，例如可以是收发电路，收发机，收发器或者通信接口。
其中，处理模块2502，用于确定第一网络切片的信息和第二网络切片的信息，其中，第一网络切片为终端设备的会话关联的网络切片，第二网络切片与第一网络切片具有映射关系。收发模块2501，用于向第一接入网设备发送第一网络切片的信息和第二网络切片的信息。
可选的，处理模块2502具体用于：通过收发模块2501接收来自移动性管理网元的第二网络切片的信息和第一网络切片的信息。
可选的，处理模块2502具体用于：通过收发模块2501接收来自移动性管理网元的第一网络切片的信息；根据第一网络切片的信息，以及第二网络切片与第一网络切片的映射信息，确定第二网络切片的信息。
可选的，第一网络切片为终端设备允许的NSSAI所指示的网络切片中的网络切片；收发模块2501，还用于接收来自所述移动性管理网元的映射信息。
其中，上述方法实施例涉及的各步骤的所有相关内容均可以援引到对应功能模块的功能描述，在此不再赘述。
在本实施例中，该第二接入网设备250以采用集成的方式划分各个功能模块的形式来呈现。这里的“模块”可以指特定ASIC，电路，执行一个或多个软件或固件程序的处理器和存储器，集成逻辑电路，和/或其他可以提供上述功能的器件。在一个简单的实施例中，本领域的技术人员可以想到该第二接入网设备250可以采用图4所示的通信设备400的形式。
比如，图4所示的通信设备400中的处理器401可以通过调用存储器403中存储的计算机执行指令，使得通信设备400执行上述方法实施例中的网络切片选择的方法。
具体的，图25中的收发模块2501和处理模块2502的功能/实现过程可以通过图4所示的通信设备400中的处理器401调用存储器403中存储的计算机执行指令来实现。或者，图25中的处理模块2502的功能/实现过程可以通过图4所示的通信设备400中的处理器401调用存储器403中存储的计算机执行指令来实现，图25中的收发模块2501的功能/实现过程可以通过图4中所示的通信设备400中的通信接口404来实现。
由于本实施例提供的第二接入网设备250可执行上述的网络切片选择的方法，因此其所能获得的技术效果可参考上述方法实施例，在此不再赘述。
需要说明的是，以上模块或单元的一个或多个可以软件、硬件或二者结合来实现。当以上任一模块或单元以软件实现的时候，所述软件以计算机程序指令的方式存在，并被存储在存储器中，处理器可以用于执行所述程序指令并实现以上方法流程。该处理器可以内置于SoC(片上系统)或ASIC，也可是一个独立的半导体芯片。该处理器内处理用于执行软件指令以进行运算或处理的核外，还可进一步包括必要的硬件加速器，如现场可编程门阵列(field programmable gate array，FPGA)、PLD(可编程逻辑器件)、或者实现专用逻辑运算的逻辑电路。
当以上模块或单元以硬件实现的时候，该硬件可以是CPU、微处理器、数字信号处理(digital signal processing，DSP)芯片、微控制单元(microcontroller unit，MCU)、人工智能处理器、ASIC、SoC、FPGA、PLD、专用数字电路、硬件加速器或非集成的分立器件中的任一个或任一组合，其可以运行必要的软件或不依赖于软件以执行以上方法流程。
可选的，本申请实施例还提供了一种通信装置(例如，该通信装置可以是芯片或芯片系统)，该通信装置包括处理器，用于实现上述任一方法实施例中的方法。在一种可能的设计中，该通信装置还包括存储器。该存储器，用于保存必要的程序指令和数据，处理器可以调用存储器中存储的程序代码以指令该通信装置执行上述任一方法实施例中的方法。当然，存储器也可以不在该通信装置中。该通信装置是芯片系统时，可以由芯片构成，也可以包含芯片和其他分立器件，本申请实施例对此不作具体限定。
在上述实施例中，可以全部或部分地通过软件、硬件、固件或者其任意组合来实现。当使用软件程序实现时，可以全部或部分地以计算机程序产品的形式来实现。该计算机程序产品包括一个或多个计算机指令。在计算机上加载和执行计算机程序指令时，全部或部分地产生按照本申请实施例所述的流程或功能。所述计算机可以是通用计算机、专用计算机、计算机网络、或者其他可编程装置。所述计算机指令可以存储在计算机可读存储介质中，或者从一个计算机可读存储介质向另一个计算机可读存储介质传输，例如，所述计算机指令可以从一个网站站点、计算机、服务器或者数据中心通过有线(例如同轴电缆、光纤、数字用户线(digital subscriber line，DSL))或无线(例如红外、无线、微波等)方式向另一个网站站点、计算机、服务器或数据中心进行传输。所述计算机可读存储介质可以是计算机能够存取的任何可用介质或者是包含一个或多个可以用介质集成的服务器、数据中心等数据存储设备。所述可用介质可以是磁性介质(例如，软盘、硬盘、磁带)，光介质(例如，DVD)、或者半导体 介质(例如固态硬盘(solid state disk，SSD))等。
尽管在此结合各实施例对本申请进行了描述，然而，在实施所要求保护的本申请过程中，本领域技术人员通过查看所述附图、公开内容、以及所附权利要求书，可理解并实现所述公开实施例的其他变化。在权利要求中，“包括”(comprising)一词不排除其他组成部分或步骤，“一”或“一个”不排除多个的情况。单个处理器或其他单元可以实现权利要求中列举的若干项功能。相互不同的从属权利要求中记载了某些措施，但这并不表示这些措施不能组合起来产生良好的效果。
尽管结合具体特征及其实施例对本申请进行了描述，显而易见的，在不脱离本申请的精神和范围的情况下，可对其进行各种修改和组合。相应地，本说明书和附图仅仅是所附权利要求所界定的本申请的示例性说明，且视为已覆盖本申请范围内的任意和所有修改、变化、组合或等同物。显然，本领域的技术人员可以对本申请进行各种改动和变型而不脱离本申请的精神和范围。这样，倘若本申请的这些修改和变型属于本申请权利要求及其等同技术的范围之内，则本申请也意图包含这些改动和变型在内。

Claims (54)

  1. 一种网络切片选择的方法，其特征在于，所述方法包括：
    移动性管理网元确定终端设备的拜访地网络中的第一网络切片能够服务所述终端设备的第一会话；
    所述移动性管理网元触发所述第一会话从第二网络切片迁移到所述第一网络切片，其中，所述第二网络切片为所述第一会话在所述拜访地网络当前关联的网络切片。
  2. 根据权利要求1所述的方法，其特征在于，所述移动性管理网元确定终端设备的拜访地网络中的第一网络切片能够服务所述终端设备的第一会话，包括：
    所述移动性管理网元确定所述终端设备移出了所述第二网络切片的服务范围，且所述终端设备当前位于所述第一网络切片的服务范围内；
    其中，所述第一网络切片与第三网络切片具有映射关系，所述第三网络切片为所述第一会话在所述终端设备的归属地网络关联的网络切片。
  3. 根据权利要求2所述的方法，其特征在于，所述方法还包括：
    所述移动性管理网元向第一会话管理网元发送第一指示信息，所述第一指示信息用于指示所述第一会话管理网元发起所述第一会话的修改流程；
    所述移动性管理网元接收来自所述第一会话管理网元的第一信息和第二信息，其中，所述第一信息包括所述第一会话的标识和所述第一网络切片的单网络切片选择辅助信息S-NSSAI，所述第二信息包括所述第一会话的标识、所述第一网络切片的S-NSSAI和所述第三网络切片的S-NSSAI；
    所述移动性管理网元向第一接入网设备发送所述第一信息；以及，所述移动性管理网元向所述终端设备发送所述第二信息，其中，所述第一信息和所述第二信息用于更新所述第一会话在所述拜访地网络对应的S-NSSAI。
  4. 根据权利要求1所述的方法，其特征在于，所述移动性管理网元确定终端设备的拜访地网络中的第一网络切片能够服务所述终端设备的第一会话，包括：
    所述移动性管理网元接收来自第一接入网设备的第二指示信息，所述第二指示信息用于指示所述第一接入网设备支持的所述第一网络切片能够服务所述第一会话。
  5. 根据权利要求4所述的方法，其特征在于，在所述移动性管理网元接收来自第一接入网设备的第一指示信息之前，所述方法还包括：
    所述移动性管理网元确定所述第一会话在所述拜访地网络与除所述第二网络切片之外的其他网络切片关联，其中，所述其他网络切片与第三网络切片具有映射关系，且所述其他网络切片包括所述第一网络切片，所述第三网络切片为所述第一会话在所述终端设备的归属地网络关联的网络切片；
    所述移动性管理网元向第二接入网设备发送所述其他网络切片的单网络切片选择辅助信息S-NSSAI，其中，所述第二接入网设备为支持所述第二网络切片的接入网设备。
  6. 根据权利要求2、4或5所述的方法，其特征在于，所述方法还包括：
    所述移动性管理网元向所述终端设备发送第三指示信息，所述第三指示信息用于指示所述终端设备发起所述第一会话关联的业务请求流程，所述业务请求流程用于建立所述第一会话的空口资源，其中，所述空口资源与所述第一网络切片关联。
  7. 根据权利要求2、4或5所述的方法，其特征在于，所述方法还包括：
    所述移动性管理网元向第一会话管理网元发送第一消息，所述第一消息用于请求所述第一会话管理网元建立所述第一会话的空口资源，其中，所述空口资源与所述第一网络切片关联。
  8. 根据权利要求6或7所述的方法，其特征在于，所述方法还包括：
    所述移动性管理网元向所述终端设备发送与所述第一会话的标识对应的所述第一网络切片的S-NSSAI和第三网络切片的S-NSSAI，所述第三网络切片为所述第一会话在所述终端设备的归属地网络关联的网络切片。
  9. 根据权利要求1-8任一项所述的方法，其特征在于，所述移动性管理网元触发所述第一会话从第二网络切片迁移到所述第一网络切片，包括：
    所述移动性管理网元向第一会话管理网元发送第二消息，所述第二消息用于请求第一用户面网元与第三用户面网元之间的用户面资源的建立，其中，所述第一会话管理网元为所述第一网络切片中服务所述第一会话的会话管理网元，所述第一用户面网元为所述第一网络切片中服务所述第一会话的用户面网元，所述第三用户面网元为第三网络切片中服务所述第一会话的用户面网元，所述第三网络切片为所述第一会话在所述终端设备的归属地网络关联的网络切片。
  10. 根据权利要求1-8任一项所述的方法，其特征在于，所述移动性管理网元触发所述第一会话从第二网络切片迁移到所述第一网络切片，包括：
    所述移动性管理网元获取所述第一会话在第三网络切片的上下文信息，所述第三网络切片为所述第一会话在所述终端设备的归属地网络关联的网络切片；
    所述移动性管理网元向第一会话管理网元发送第三消息，所述第三消息包括所述第一会话在所述第三网络切片的上下文信息，所述第三消息用于请求第一用户面网元与第三用户面网元之间的用户面资源的建立，其中，所述第一会话管理网元为所述第一网络切片中服务所述第一会话的会话管理网元，所述第一用户面网元为所述第一网络切片中服务所述第一会话的用户面网元，所述第三用户面网元为所述第三网络切片中服务所述第一会话的用户面网元。
  11. 根据权利要求10所述的方法，其特征在于，所述移动性管理网元获取所述第一会话在第三网络切片的上下文信息，包括：
    所述移动性管理网元向第二会话管理网元发送第四消息，所述第四消息用于请求所述第一会话在所述第三网络切片的上下文信息，所述第二会话管理网元为所述第二网络切片中服务所述第一会话的会话管理网元；
    所述移动性管理网元接收来自所述第二会话管理网元的所述第一会话在所述第三网络切片的上下文信息。
  12. 根据权利要求1-11任一项所述的方法，其特征在于，所述方法还包括：
    所述移动性管理网元向所述终端设备发送更新后的允许的NSSAI、以及所述第一网络切片的S-NSSAI和第三网络切片的S-NSSAI的映射关系，其中，所述更新后的允许的NSSAI中包括所述第一网络切片的S-NSSAI，所述第三网络切片为所述第一会话在所述终端设备的归属地网络关联的网络切片。
  13. 一种网络切片选择的方法，其特征在于，所述方法包括：
    第一接入网设备接收来自第二接入网设备的第一网络切片的单网络切片选择辅助信息S-NSSAI和第二网络切片的S-NSSAI，其中，所述第一网络切片和所述第二网络切片是终端设备的第一会话在所述终端设备的拜访地网络与第三网络切片具有映射关系的网络切片，且所述第二网络切片为所述第一会话在所述拜访地网络当前关联的网络切片，所述第三网络切片为所述第一会话在所述终端设备的归属地网络关联的网络切片；
    所述第一接入网设备确定不支持所述第二网络切片，支持所述第一网络切片；
    所述第一接入网设备向移动性管理网元发送第二指示信息，所述第二指示信息用于指示所述第一网络切片能够服务所述第一会话。
  14. 一种移动性管理网元，其特征在于，所述移动性管理网元包括：处理模块和收发模块；
    所述处理模块，用于确定终端设备的拜访地网络中的第一网络切片能够服务所述终端设备的第一会话；
    所述处理模块，还用于通过所述收发模块触发所述第一会话从第二网络切片迁移到所述第一网络切片，其中，所述第二网络切片为所述第一会话在所述拜访地网络当前关联的网络切片。
  15. 根据权利要求14所述的移动性管理网元，其特征在于，所述处理模块，用于确定终端设备的拜访地网络中的第一网络切片能够服务所述终端设备的第一会话，包括：
    用于确定所述终端设备移出了所述第二网络切片的服务范围，且所述终端设备当前位于所述第一网络切片的服务范围内；其中，所述第一网络切片与第三网络切片具有映射关系，所述第三网络切片为所述第一会话在所述终端设备的归属地网络关联的网络切片。
  16. 根据权利要求15所述的移动性管理网元，其特征在于，所述收发模块，还用于向第一会话管理网元发送第一指示信息，所述第一指示信息用于指示所述第一会话管理网元发起所述第一会话的修改流程；
    所述收发模块，还用于接收来自所述第一会话管理网元的第一信息和第二信息，其中，所述第一信息包括所述第一会话的标识和所述第一网络切片的单网络切片选择辅助信息S-NSSAI，所述第二信息包括所述第一会话的标识、所述第一网络切片的S-NSSAI和所述第三网络切片的S-NSSAI；
    所述收发模块，还用于向第一接入网设备发送所述第一信息；以及，向所述终端设备发送所述第二信息，其中，所述第一信息和所述第二信息用于更新所述第一会话在所述拜访地网络对应的S-NSSAI。
  17. 根据权利要求14所述的移动性管理网元，其特征在于，所述处理模块，用于确定终端设备的拜访地网络中的第一网络切片能够服务所述终端设备的第一会话，包括：
    用于通过所述收发模块接收来自第一接入网设备的第二指示信息，所述第二指示信息用于指示所述第一接入网设备支持的所述第一网络切片能够服务所述第一会话。
  18. 根据权利要求17所述的移动性管理网元，其特征在于，所述处理模块，还用 于确定所述第一会话在所述拜访地网络与除所述第二网络切片之外的其他网络切片关联，其中，所述其他网络切片与第三网络切片具有映射关系，且所述其他网络切片包括所述第一网络切片，所述第三网络切片为所述第一会话在所述终端设备的归属地网络关联的网络切片；
    所述收发模块，还用于向第二接入网设备发送所述其他网络切片的单网络切片选择辅助信息S-NSSAI，其中，所述第二接入网设备为支持所述第二网络切片的接入网设备。
  19. 根据权利要求15、17或18所述的移动性管理网元，其特征在于，所述收发模块，还用于向所述终端设备发送第三指示信息，所述第三指示信息用于指示所述终端设备发起所述第一会话关联的业务请求流程，所述业务请求流程用于建立所述第一会话的空口资源，其中，所述空口资源与所述第一网络切片关联。
  20. 根据权利要求15、17或18所述的移动性管理网元，其特征在于，所述收发模块，还用于向第一会话管理网元发送第一消息，所述第一消息用于请求所述第一会话管理网元建立所述第一会话的空口资源，其中，所述空口资源与所述第一网络切片关联。
  21. 根据权利要求19或20所述的移动性管理网元，其特征在于，所述收发模块，还用于向所述终端设备发送与所述第一会话的标识对应的所述第一网络切片的S-NSSAI和第三网络切片的S-NSSAI，所述第三网络切片为所述第一会话在所述终端设备的归属地网络关联的网络切片。
  22. 根据权利要求14-21任一项所述的移动性管理网元，其特征在于，所述处理模块，用于通过所述收发模块触发所述第一会话从第二网络切片迁移到所述第一网络切片，包括：
    用于通过所述收发模块向第一会话管理网元发送第二消息，所述第二消息用于请求第一用户面网元与第三用户面网元之间的用户面资源的建立，其中，所述第一会话管理网元为所述第一网络切片中服务所述第一会话的会话管理网元，所述第一用户面网元为所述第一网络切片中服务所述第一会话的用户面网元，所述第三用户面网元为第三网络切片中服务所述第一会话的用户面网元，所述第三网络切片为所述第一会话在所述终端设备的归属地网络关联的网络切片。
  23. 根据权利要求14-21任一项所述的移动性管理网元，其特征在于，所述处理模块，用于通过所述收发模块触发所述第一会话从第二网络切片迁移到所述第一网络切片，包括：
    用于获取所述第一会话在第三网络切片的上下文信息，所述第三网络切片为所述第一会话在所述终端设备的归属地网络关联的网络切片；通过所述收发模块向第一会话管理网元发送第三消息，所述第三消息包括所述第一会话在所述第三网络切片的上下文信息，所述第三消息用于请求第一用户面网元与第三用户面网元之间的用户面资源的建立，其中，所述第一会话管理网元为所述第一网络切片中服务所述第一会话的会话管理网元，所述第一用户面网元为所述第一网络切片中服务所述第一会话的用户面网元，所述第三用户面网元为所述第三网络切片中服务所述第一会话的用户面网元。
  24. 根据权利要求23所述的移动性管理网元，其特征在于，所述处理模块，用于 获取所述第一会话在第三网络切片的上下文信息，包括：
    用于通过所述收发模块向第二会话管理网元发送第四消息，所述第四消息用于请求所述第一会话在所述第三网络切片的上下文信息，所述第二会话管理网元为所述第二网络切片中服务所述第一会话的会话管理网元；通过所述收发模块接收来自所述第二会话管理网元的所述第一会话在所述第三网络切片的上下文信息。
  25. 根据权利要求14-24任一项所述的移动性管理网元，其特征在于，所述收发模块，还用于向所述终端设备发送更新后的允许的NSSAI、以及所述第一网络切片的S-NSSAI和第三网络切片的S-NSSAI的映射关系，其中，所述更新后的允许的NSSAI中包括所述第一网络切片的S-NSSAI，所述第三网络切片为所述第一会话在所述终端设备的归属地网络关联的网络切片。
  26. 一种第一接入网设备，其特征在于，所述第一接入网设备包括：处理模块和收发模块；
    所述收发模块，用于接收来自第二接入网设备的第一网络切片的单网络切片选择辅助信息S-NSSAI和第二网络切片的S-NSSAI，其中，所述第一网络切片和所述第二网络切片是终端设备的第一会话在所述终端设备的拜访地网络与第三网络切片具有映射关系的网络切片，且所述第二网络切片为所述第一会话在所述拜访地网络当前关联的网络切片，所述第三网络切片为所述第一会话在所述终端设备的归属地网络关联的网络切片；
    所述处理模块，用于确定不支持所述第二网络切片，支持所述第一网络切片；
    所述收发模块，还用于向移动性管理网元发送第二指示信息，所述第二指示信息用于指示所述第一网络切片能够服务所述第一会话。
  27. 一种网络切片选择的方法，其特征在于，所述方法包括：
    第一接入网设备接收来自第二接入网设备的第一网络切片的信息，其中，所述第一网络切片为终端设备的会话关联的网络切片；
    所述第一接入网设备确定所述第一接入网设备不支持所述第一网络切片；
    所述第一接入网设备确定第二网络切片，其中，所述第一接入网设备支持所述第二网络切片，且所述第二网络切片与所述第一网络切片具有映射关系；
    所述第一接入网设备向会话管理网元发送指示信息，所述指示信息用于指示所述第二网络切片能够服务所述会话。
  28. 根据权利要求27所述的方法，其特征在于，所述第一接入网设备确定第二网络切片，包括：
    所述第一接入网设备根据所述第一网络切片的信息，以及所述第二网络切片与所述第一网络切片的映射信息，确定所述第二网络切片。
  29. 根据权利要求28所述的方法，其特征在于，所述方法还包括：
    所述第一接入网设备向移动性管理网元发送所述第二网络切片的信息；
    所述第一接入网设备接收来自所述移动性管理网元的所述第二网络切片与所述第一网络切片的映射信息。
  30. 一种网络切片选择的方法，其特征在于，所述方法包括：
    第二接入网设备确定第一网络切片的信息和第二网络切片的信息，其中，所述第 一网络切片为终端设备的会话关联的网络切片，所述第二网络切片与所述第一网络切片具有映射关系；
    所述第二接入网设备向第一接入网设备发送所述第一网络切片的信息和所述第二网络切片的信息。
  31. 根据权利要求30所述的方法，其特征在于，所述第二接入网设备确定第一网络切片的信息和第二网络切片的信息，包括：
    所述第二接入网设备接收来自移动性管理网元的所述第二网络切片的信息和所述第一网络切片的信息。
  32. 根据权利要求30所述的方法，其特征在于，所述第二接入网设备确定第一网络切片的信息和第二网络切片的信息，包括：
    所述第二接入网设备接收来自移动性管理网元的所述第一网络切片的信息；
    所述第二接入网设备根据所述第一网络切片的信息，以及所述第二网络切片与所述第一网络切片的映射信息，确定所述第二网络切片的信息。
  33. 根据权利要求32所述的方法，其特征在于，所述第一网络切片为所述终端设备允许的网络切片选择辅助信息NSSAI所指示的网络切片中的网络切片，所述方法还包括：
    所述第二接入网设备接收来自所述移动性管理网元的所述映射信息。
  34. 一种网络切片选择的方法，其特征在于，所述方法包括：
    第一接入网设备接收来自第二接入网设备的第一网络切片的信息和第二网络切片的信息，其中，所述第一网络切片为终端设备的会话关联的网络切片，所述第二网络切片与所述第一网络切片具有映射关系；
    所述第一接入网设备确定所述第一接入网设备不支持所述第一网络切片，支持所述第二网络切片；
    所述第一接入网设备向会话管理网元发送指示信息，所述指示信息用于指示所述第二网络切片能够服务所述会话。
  35. 一种网络切片选择的方法，其特征在于，所述方法包括：
    移动性管理网元确定第一网络切片的信息和第二网络切片的信息，其中，所述第二网络切片与所述第一网络切片具有映射关系；
    所述移动性管理网元向接入网设备发送所述第一网络切片与所述第二网络切片的映射信息。
  36. 根据权利要求35所述的方法，其特征在于，所述移动性管理网元确定第一网络切片的信息和第二网络切片的信息，包括：
    所述移动性管理网元确定第一网络切片的信息；
    所述移动性管理网元根据所述第一网络切片的信息，以及所述第二网络切片与所述第一网络切片的映射信息，确定所述第二网络切片的信息。
  37. 根据权利要求35或36所述的方法，其特征在于，所述第一网络切片为所述接入网设备支持的网络切片。
  38. 根据权利要求35或36所述的方法，其特征在于，所述第一网络切片为终端设备的会话关联的网络切片。
  39. 根据权利要求35或36所述的方法，其特征在于，所述第一网络切片为终端设备允许的网络切片选择辅助信息NSSAI所指示的网络切片。
  40. 根据权利要求27-39任一项所述的方法，其特征在于，所述第二网络切片与所述第一网络切片具有映射关系，包括：
    所述第一网络切片和所述第二网络切片能够提供相同的业务类型；
    或者，所述第一网络切片和所述第二网络切片能够共享网络切片实例。
  41. 一种第一接入网设备，其特征在于，所述第一接入网设备包括：收发模块和处理模块；
    所述收发模块，用于接收来自第二接入网设备的第一网络切片的信息，其中，所述第一网络切片为终端设备的会话关联的网络切片；
    所述处理模块，用于确定所述第一接入网设备不支持所述第一网络切片；
    所述处理模块，还用于确定第二网络切片，其中，所述第一接入网设备支持所述第二网络切片，且所述第二网络切片与所述第一网络切片具有映射关系；
    所述收发模块，还用于向会话管理网元发送指示信息，所述指示信息用于指示所述第二网络切片能够服务所述会话。
  42. 根据权利要求41所述的第一接入网设备，其特征在于，所述处理模块用于确定第二网络切片，包括：
    用于根据所述第一网络切片的信息，以及所述第二网络切片与所述第一网络切片的映射信息，确定所述第二网络切片。
  43. 根据权利要求42所述的第一接入网设备，其特征在于，
    所述收发模块，还用于向移动性管理网元发送所述第二网络切片的信息；
    所述收发模块，还用于接收来自所述移动性管理网元的所述第二网络切片与所述第一网络切片的映射信息。
  44. 一种第二接入网设备，其特征在于，所述第二接入网设备包括：处理模块和收发模块；
    所述处理模块，用于确定第一网络切片的信息和第二网络切片的信息，其中，所述第一网络切片为终端设备的会话关联的网络切片，所述第二网络切片与所述第一网络切片具有映射关系；
    所述收发模块，用于向第一接入网设备发送所述第一网络切片的信息和所述第二网络切片的信息。
  45. 根据权利要求44所述的第二接入网设备，其特征在于，所述处理模块具体用于：
    通过所述收发模块接收来自移动性管理网元的所述第二网络切片的信息和所述第一网络切片的信息。
  46. 根据权利要求44所述的第二接入网设备，其特征在于，所述处理模块具体用于：
    通过所述收发模块接收来自移动性管理网元的所述第一网络切片的信息；根据所述第一网络切片的信息，以及所述第二网络切片与所述第一网络切片的映射信息，确定所述第二网络切片的信息。
  47. 根据权利要求46所述的第二接入网设备，其特征在于，所述第一网络切片为所述终端设备允许的网络切片选择辅助信息NSSAI所指示的网络切片中的网络切片；
    所述收发模块，还用于接收来自所述移动性管理网元的所述映射信息。
  48. 一种第一接入网设备，其特征在于，所述第一接入网设备包括：处理模块和收发模块；
    所述收发模块，用于接收来自第二接入网设备的第一网络切片的信息和第二网络切片的信息，其中，所述第一网络切片为终端设备的会话关联的网络切片，所述第二网络切片与所述第一网络切片具有映射关系；
    所述处理模块，用于确定所述第一接入网设备不支持所述第一网络切片，支持所述第二网络切片；
    所述收发模块，还用于向会话管理网元发送指示信息，所述指示信息用于指示所述第二网络切片能够服务所述会话。
  49. 一种移动性管理网元，其特征在于，所述移动性管理网元包括：处理模块和收发模块；
    所述处理模块，用于确定第一网络切片的信息和第二网络切片的信息，其中，所述第二网络切片与所述第一网络切片具有映射关系；
    所述收发模块，用于向接入网设备发送所述第一网络切片与所述第二网络切片的映射信息。
  50. 根据权利要求49所述的移动性管理网元，其特征在于，所述处理模块具体用于：
    确定第一网络切片的信息；根据所述第一网络切片的信息，以及所述第二网络切片与所述第一网络切片的映射信息，确定所述第二网络切片的信息。
  51. 根据权利要求49或50所述的移动性管理网元，其特征在于，所述第一网络切片为所述接入网设备支持的网络切片。
  52. 根据权利要求49或50所述的移动性管理网元，其特征在于，所述第一网络切片为终端设备的会话关联的网络切片。
  53. 根据权利要求49或50所述的移动性管理网元，其特征在于，所述第一网络切片为终端设备允许的网络切片选择辅助信息NSSAI所指示的网络切片。
  54. 根据权利要求41-43任一项所述的第一接入网设备或者权利要求44-47任一项所述的第二接入网设备或者权利要求48所述的第一接入网设备或者权利要求49-53任一项所述的移动性管理网元，其特征在于，所述第二网络切片与所述第一网络切片具有映射关系，包括：
    所述第一网络切片和所述第二网络切片能够提供相同的业务类型；
    或者，所述第一网络切片和所述第二网络切片能够共享网络切片实例。
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