WO2019214407A1 - 一种网元选择方法及装置 - Google Patents

一种网元选择方法及装置 Download PDF

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Publication number
WO2019214407A1
WO2019214407A1 PCT/CN2019/082963 CN2019082963W WO2019214407A1 WO 2019214407 A1 WO2019214407 A1 WO 2019214407A1 CN 2019082963 W CN2019082963 W CN 2019082963W WO 2019214407 A1 WO2019214407 A1 WO 2019214407A1
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WO
WIPO (PCT)
Prior art keywords
network element
subscription information
communication system
session management
management function
Prior art date
Application number
PCT/CN2019/082963
Other languages
English (en)
French (fr)
Inventor
姚琦
时书锋
Original Assignee
华为技术有限公司
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
Priority claimed from CN201810481106.6A external-priority patent/CN110461013A/zh
Application filed by 华为技术有限公司 filed Critical 华为技术有限公司
Priority to KR1020197027905A priority Critical patent/KR102285054B1/ko
Priority to EP19783965.7A priority patent/EP3598796B1/en
Priority to JP2019547504A priority patent/JP6825793B2/ja
Priority to BR112019022249-9A priority patent/BR112019022249A2/pt
Priority to EP21193229.8A priority patent/EP3979698A1/en
Priority to US16/584,242 priority patent/US10856218B2/en
Publication of WO2019214407A1 publication Critical patent/WO2019214407A1/zh
Priority to US17/013,127 priority patent/US11284341B2/en

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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
    • H04W28/00—Network traffic management; Network resource management
    • H04W28/02—Traffic management, e.g. flow control or congestion control
    • H04W28/08—Load balancing or load distribution
    • H04W28/09—Management thereof
    • H04W28/0958—Management thereof based on metrics or performance parameters
    • H04W28/0967—Quality of Service [QoS] parameters
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W28/00—Network traffic management; Network resource management
    • H04W28/16—Central resource management; Negotiation of resources or communication parameters, e.g. negotiating bandwidth or QoS [Quality of Service]
    • H04W28/18—Negotiating wireless communication parameters
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W28/00—Network traffic management; Network resource management
    • H04W28/02—Traffic management, e.g. flow control or congestion control
    • H04W28/0215—Traffic management, e.g. flow control or congestion control based on user or device properties, e.g. MTC-capable devices
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W8/00—Network data management
    • H04W8/18—Processing of user or subscriber data, e.g. subscribed services, user preferences or user profiles; Transfer of user or subscriber data
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W8/00—Network data management
    • H04W8/22—Processing or transfer of terminal data, e.g. status or physical capabilities
    • H04W8/24—Transfer of terminal data
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W88/00—Devices specially adapted for wireless communication networks, e.g. terminals, base stations or access point devices
    • H04W88/02—Terminal devices
    • H04W88/06—Terminal devices adapted for operation in multiple networks or having at least two operational modes, e.g. multi-mode terminals

Definitions

  • the present application relates to the field of wireless communication technologies, and in particular, to a network element selection method and apparatus.
  • the fifth generation (Fifth Generation, 5G) mobile communication technology came into being.
  • the coverage of the 5G network is insufficient. Therefore, when the location of the user equipment (User Equipment, UE) changes, the UE needs to switch sessions between the 5G network and the fourth generation (4G) network.
  • UE User Equipment
  • the MME Mobility Management Entity
  • the MME determines that the UE can support the 4G system and the 5G system
  • the MME selects the UE for the UE.
  • the session management function network element establishes a connection.
  • the UE does not need to use the services of the 5G network or the services of the 5G network, that is, the UEs supporting the 4G system and the 5G system do not have interworking requirements. Therefore, the MME does not need to be the UE at this time. Select the connected session management function network element.
  • the above situation has a problem that the network element selection is unreasonable, and may cause the load of the combined session management function network element to be heavy.
  • the embodiment of the present application provides a network element selection method and device, which are used to implement a network element that supports a 4G system and a 5G system without interworking requirements.
  • the application provides a network element selection method, where the method includes:
  • the first network element in the first communication system receives the first message sent by the terminal device, where the first message is used to request to establish a session; and in response to the first message, the first network element in the first communication system Determining a target session management function network element according to the first subscription information and the second subscription information, where the first subscription information includes subscription information of the terminal device in the first communication system, and the second subscription information includes the terminal The subscription information of the device in the second communication system.
  • the first network element in the first communication system can select a suitable network element as the target session management function network element according to the first subscription information and the second subscription information, compared to whether the terminal device supports 4G according to the prior art.
  • the system and the 5G system select the network element, and the terminal device that supports the 4G system and the 5G system and does not have the interworking requirement can reasonably select the network element, and can reduce the load of the network element of the combined session management function.
  • the first subscription information may be subscription information corresponding to one or more data network identifiers of the terminal device in the first communication system.
  • the second subscription information may also be subscription information corresponding to one or more data network identifiers of the terminal device in the second communication system.
  • the first subscription information may be an indication information indicating whether the terminal device has subscribed to a certain data network identifier in the first communication system, and the second subscription information may also be an indication information indicating that the terminal device is in the second communication system. Whether a data network identifier has been signed.
  • the first network element in the first communication system determines the target session management function network element according to the first subscription information and the second subscription information, and specifically, according to the terminal device capability, the first The subscription information and the second subscription information determine the target session management function network element.
  • the first network element in the first communication system can determine the target session management function network element in combination with the terminal device capability, and the first subscription information and the second subscription information.
  • the first communication system is a 4G system
  • the second communication system is a 5G system
  • the first network element in the first communication system is an MME.
  • the first network element in the first communication system determines the target session management function network element according to the terminal device capability, the first subscription information, and the second subscription information, if the terminal device supports The first communication system and the second communication system, and the first subscription information and the second subscription information each include subscription information corresponding to the data network identifier of the session, and the MME selects a combined session management.
  • the function network element is used as the target session management network element, wherein the network management element having the session management capability of the 5G system and the session management capability of the 4G system is a combined session management function network element.
  • the MME may select the set session management function network element as the target session management function network element for the terminal device having the interworking capability and the interworking requirement.
  • the first communication system is a 4G system
  • the second communication system is a 5G system
  • the first network element in the first communication system is an MME.
  • the first network element in the first communication system determines the target session management function network element according to the terminal device capability, the first subscription information, and the second subscription information, if the terminal device supports The first communication system and the second communication system, and the first subscription information includes subscription information corresponding to the data network identifier of the session, and the second subscription information does not include a data network identifier corresponding to the session.
  • the MME selects the session management function network element in the 4G system as the target session management network element.
  • the MME can select the session management function network element in the 4G system as the target session management network element for the terminal device that has the interworking capability but does not have the interworking requirement (that is, the service that does not need to use the 5G network or the service that does not subscribe to the 5G network). It can meet the needs of the session, and thus can reduce the load of the network elements of the combined session management function.
  • the first communication system is a 5G system
  • the second communication system is a 4G system
  • the first network element in the first communication system is an AMF.
  • the first network element in the first communication system determines the target session management function network element according to the terminal device capability, the first subscription information, and the second subscription information, if the terminal device supports The first communication system and the second communication system, and the first subscription information and the second subscription information each include subscription information corresponding to the data network identifier of the session, and the AMF selects a combined session management.
  • the function network element is used as the target session management network element, wherein the network management element having the session management capability of the 5G system and the session management capability of the 4G system is a combined session management function network element.
  • the AMF can select the set session management function network element as the target session management function network element for the terminal device having the interworking capability and the interworking requirement.
  • the first communication system is a 5G system
  • the second communication system is a 4G system
  • the first network element in the first communication system is an AMF.
  • the first network element in the first communication system determines the target session management function network element according to the terminal device capability, the first subscription information, and the second subscription information, if the terminal device supports The first communication system and the second communication system, and the first subscription information includes subscription information corresponding to the data network identifier of the session, and the second subscription information does not include a subscription corresponding to the data network identifier of the session.
  • the AMF selects a session management function network element in the 5G system as the target session management network element.
  • the AMF can select the session management function network element in the 5G system as the target session management network element for the terminal device that has the interworking capability but does not have the interworking requirement (that is, the service that does not need to use the 4G network or the service that does not subscribe to the 4G network). It can meet the needs of the session, and thus can reduce the load of the network elements of the combined session management function.
  • the method further includes: the first network element in the first communication system sends a second message to the target session management function network element, so that the target session management function network element Determining a policy control network element and a charging system according to the second message.
  • the second message includes a policy control network element and a charging system indicating that the target session management function network element selects the connection or a policy control network element and a charging system in the first communication system.
  • the MME may indicate that the set session management function network element has the interworking capability through the second message.
  • the terminal device that does not have the interworking requirement that is, the service that does not need to use the 5G network or the service that does not sign the 5G network selects the policy control network element and the charging system in the 4G system, thereby reducing the combined policy control network element and meter. The load of the fee system.
  • the AMF may indicate that the set session management function network element has the interworking capability through the second message.
  • the terminal device that does not have the interworking requirement selects the policy control network element and the charging system in the 5G system, thereby reducing the combined policy control network element and meter. The load of the fee system.
  • the present application provides another method for selecting a network element, where the method includes:
  • the first network element in the first communication system receives the first message sent by the terminal device, where the first message is used to request to establish a session; and in response to the first message, the first network element in the first communication system Determining a target session management function network element according to the terminal device capability and the third subscription information of the terminal.
  • the first network element in the first communication system can select a suitable network element as the target session management function network element according to the third subscription information of the terminal, compared to whether the terminal device supports the 4G system according to the prior art.
  • the 5G system selects the network element, and the terminal device supporting the 4G system and the 5G system without interworking requirements can reasonably select the network element, and can reduce the load of the combined session management function network element.
  • the first communication system is a 4G system
  • the second communication system is a 5G system
  • the first network element in the first communication system is an MME.
  • the third subscription information of the terminal may be an indication information indicating whether the data network identifier APN corresponding to the session supports interworking with the 5G system (or 5GC).
  • the indicating that the data network identifier APN corresponding to the session supports interworking with the 5G system (or 5GC) further includes: the third subscription information of the terminal is an indication information indicating a data network corresponding to the session. Identifies whether the APN supports interworking with a DNN and a network slice identifier S-NSSAI.
  • the target session management function network element Determining, by the first network element in the first communication system, the target session management function network element according to the terminal device capability and the third subscription information of the terminal, including: if the terminal device supports the first communication system, a second communication system, and the third subscription information of the terminal indicates that the data network identifier APN corresponding to the session supports interworking with the 5G system, and the MME selects a combined session management function network element as the target session management network.
  • the set session management function network element may be a network element that has both the session management capability of the 4G system and the session management capability of the 5G system, such as SMF+PGW-C. Therefore, the MME may select the set session management function network element as the target session management function network element for the terminal device having the interworking capability and the interworking requirement.
  • the first communication system is a 4G system
  • the second communication system is a 5G system
  • the first network element in the first communication system is an MME.
  • the third subscription information of the terminal may be an indication information indicating whether the data network identifier APN corresponding to the session supports interworking with the 5G system (or 5GC).
  • the indicating that the data network identifier APN corresponding to the session supports interworking with the 5G system (or 5GC) further includes: the third subscription information of the terminal is an indication information indicating a data network corresponding to the session. Identifies whether the APN supports interworking with a DNN and a network slice identifier S-NSSAI.
  • the target session management function network element Determining, by the first network element in the first communication system, the target session management function network element according to the terminal device capability and the third subscription information of the terminal, including: if the terminal device supports the first communication system, a second communication system, and the third subscription information indicates that the data network identifier APN of the session does not support interworking with the 5G system, and the MME does not select the set session management function network element as the target session management network element. .
  • the MME does not select the associated session management function network element as the target session management network element, and the MME selects a session management function network element that is not used for interworking as the target session management network element.
  • the MME can select the session management function network element in the 4G system as the target session management network element for the terminal device that has the interworking capability but does not have the interworking requirement (that is, the APN that does not support the interworking with the 5G), and can satisfy the session requirement, and thus can Reduce the load of the network element of the combined session management function.
  • the first communication system is a 5G system
  • the second communication system is a 4G system
  • the first network element in the first communication system is an AMF.
  • the third subscription information of the terminal may be an indication information indicating whether the data network identifier DNN corresponding to the session supports interworking with a 4G system (or EPS).
  • the indicating that the data network identifier DNN corresponding to the session supports interworking with the 4G system (or EPS) further includes: the third subscription information of the terminal is an indication information indicating a data network corresponding to the session Identifies whether the DNN and the network slice identifier S-NSSAI support interworking with 4G (or EPS).
  • the target session management function network element Determining, by the first network element in the first communication system, the target session management function network element according to the terminal device capability and the third subscription information of the terminal, including: if the terminal device supports the first communication system, a second communication system, and the third subscription information of the terminal indicates that the data network identifier DNN corresponding to the session supports interworking with the 4G system (or EPS), and the AMF selects the combined session management function network element as The target session management network element.
  • the set session management function network element may be a network element that has both the session management capability of the 5G system and the session management capability of the 4G system, such as SMF+PGW-C. Therefore, the AMF can select the set session management function network element as the target session management function network element for the terminal device having the interworking capability and the interworking requirement.
  • the first communication system is a 5G system
  • the second communication system is a 4G system
  • the first network element in the first communication system is an AMF.
  • the third subscription information of the terminal may be an indication information indicating whether the data network identifier DNN corresponding to the session supports interworking with a 4G system (or EPS).
  • the indicating that the data network identifier DNN corresponding to the session supports interworking with the 4G system (or EPS) further includes: the third subscription information of the terminal is an indication information indicating a data network corresponding to the session Identifies whether the DNN and the network slice identifier S-NSSAI support interworking with 4G (or EPS).
  • the target session management function network element Determining, by the first network element in the first communication system, the target session management function network element according to the terminal device capability and the third subscription information of the terminal, including: if the terminal device supports the first communication system, a second communication system, and the third subscription information indicates that the data network identifier DNN of the session does not support interworking with the 4G system, and the AMF does not select a combined session management function network element as the target session management network element. .
  • the AMF does not select the associated session management function network element as the target session management network element, and the AMF selects a session management function network element that is not used for interworking to serve as the target session management network element.
  • the AMF can select the session management function network element in the 5G system as the target session management network element for the terminal device that has the interworking capability but does not have the interworking requirement (that is, the DNN that does not support the interworking with the 4G), and can satisfy the session requirement, and thus can Reduce the load of the network element of the combined session management function.
  • the method further includes: the first network element in the first communication system sends a second message to the target session management function network element, so that the target session management function network element Determining a policy control network element and a charging system according to the second message.
  • the second message includes a policy control network element and a charging system indicating that the target session management function network element selects the connection or the policy control network element and the charging system in the first communication system.
  • the MME may indicate that the set session management function network element has the interworking capability through the second message.
  • the terminal device that does not have the interworking requirement that is, the service that does not need to use the 5G network or the service that does not sign the 5G network selects the policy control network element and the charging system in the 4G system, thereby reducing the combined policy control network element and meter. The load of the fee system.
  • the AMF may indicate that the set session management function network element has the interworking capability through the second message.
  • the terminal device that does not have the interworking requirement selects the policy control network element and the charging system in the 5G system, thereby reducing the combined policy control network element and meter. The load of the fee system.
  • a third aspect a network element selecting apparatus, the apparatus comprising: a receiving unit, configured to receive a first message sent by a terminal device, where the first message is used to request to establish a session; and the processing unit is configured to respond to the first a message, the target session management function network element is determined according to the first subscription information and the second subscription information, where the first subscription information includes subscription information of the terminal device in the first communication system, and the second subscription information includes The subscription information of the terminal device in the second communication system.
  • the processing unit is specifically configured to: determine the target session management function network element according to the terminal device capability, the first subscription information, and the second subscription information.
  • the first communication system is a 4G system
  • the second communication system is a 5G system
  • the device is an MME
  • the processing unit is specifically configured to: if the terminal device supports the The first communication system and the second communication system are described, and the first subscription information and the second subscription information each include subscription information corresponding to the data network identifier of the session, and then the combined session management function network element is selected as The target session management network element, wherein the network management element having the session management capability of the 5G system and the session management capability of the 4G system is a combined session management function network element.
  • the first communication system is a 4G system
  • the second communication system is a 5G system
  • the device is an MME
  • the processing unit is specifically configured to: if the terminal device supports the The first communication system and the second communication system, and the first subscription information includes subscription information corresponding to the data network identifier of the session, and the second subscription information does not include a subscription corresponding to the data network identifier of the session.
  • the session management function network element in the 4G system is selected as the target session management network element.
  • the first communication system is a 5G system
  • the second communication system is a 4G system
  • the device is an AMF
  • the processing unit is specifically configured to: if the terminal device supports the The first communication system and the second communication system are described, and the first subscription information and the second subscription information each include subscription information corresponding to the data network identifier of the session, and then the combined session management function network element is selected as The target session management network element, wherein the network management element having the session management capability of the 5G system and the session management capability of the 4G system is a combined session management function network element.
  • the first communication system is a 5G system
  • the second communication system is a 4G system
  • the device is an AMF
  • the processing unit is specifically configured to: if the terminal device supports the The first communication system and the second communication system, and the first subscription information includes subscription information corresponding to the data network identifier of the session, and the second subscription information does not include subscription information corresponding to the data network identifier of the session. Then, the session management function network element in the 5G system is selected as the target session management network element.
  • the method further includes: a sending unit, configured to send a second message to the target session management function network element, so that the target session management function network element determines a policy control network according to the second message Yuan and billing system.
  • a fourth aspect of the present invention discloses another apparatus for selecting a network element, the apparatus comprising:
  • a receiving unit configured to receive a first message sent by the terminal device, where the first message is used to request to establish a session
  • the processing unit is configured to determine, according to the terminal device capability and the third subscription information of the terminal, the target session management function network element in response to the first message.
  • the first communication system is a 5G system
  • the second communication system is a 4G system
  • the network element selection device is an access and mobility management function network element AMF in the 5G system.
  • the processing unit is specifically configured to: if the terminal device supports the first communication system and the second communication system, and the third subscription information of the terminal indicates that the data network identifier DNN corresponding to the session supports the 4G system interworking Then, the set session management function network element is selected as the target session management network element.
  • the first communication system is a 5G system
  • the second communication system is a 4G system
  • the network element selection device is an access and mobility management function network element AMF in the 5G system.
  • the processing unit is specifically configured to: if the terminal device supports the first communication system and the second communication system, and the third subscription information indicates that the data network identifier DNN of the session does not support interworking with the 4G system,
  • the set session management function network element is not selected as the target session management network element.
  • the selecting the session management function network element as the target session management network element includes: selecting a session management function network element in the 5G system as the target session management network element.
  • the first communication system is a 4G system
  • the second communication system is a 5G system
  • the device selected by the network element is a mobility management function network element MME in the 4G system
  • the processing unit is specifically configured to: if the terminal device supports the first communication system and the second communication system, and the third subscription information of the terminal indicates that the data network identifier APN corresponding to the session supports the 5G system interworking Then, the set session management function network element is selected as the target session management network element.
  • the first communication system is a 4G system
  • the second communication system is a 5G system
  • the device selected by the network element is a mobility management function network element MME in the 4G system:
  • the processing unit is specifically configured to: if the terminal device supports the first communication system and the second communication system, and the third subscription information indicates that the data network identifier APN of the session does not support interworking with the 5G system,
  • the set session management function network element is not selected as the target session management network element.
  • the selecting the session management function network element as the target session management network element includes: selecting the session management function network element in the 4G system as the target session management network element.
  • the device further includes:
  • a sending unit configured to send a second message to the target session management function network element, so that the target session management function network element determines a policy control network element and a charging system according to the second message.
  • the embodiment of the present application provides a network element selection device, where the device may be a first network element in the first communication system, or a chip in the first network element in the first communication system.
  • the apparatus can include a processing unit and a transceiver unit.
  • the processing unit may be a processor, and the transceiver unit may be a transceiver;
  • the first network element in the first communication system may further include a storage unit, where The storage unit may be a memory; the storage unit is configured to store an instruction, the processing unit executes an instruction stored by the storage unit, so that the first network element in the first communication system performs the first aspect or the first aspect Possible methods in design.
  • the processing unit may be a processor, and the transceiver unit may be an input/output interface, a pin or a circuit, etc.; the processing unit executes the storage unit
  • the stored instruction unit is used to store an instruction, and the storage unit may be a storage unit (for example, a register, a cache, etc.) in the chip, or may be located in the first network element in the first communication system.
  • a storage unit external to the chip eg, read only memory, random access memory, etc. to cause the first network element in the first communication system to perform the method of any of the first aspect or the first aspect of the first aspect
  • the embodiment of the present application further provides a computer readable storage medium, where the computer readable storage medium stores a computer program, when the computer program is run on a computer, causing the computer to perform the first aspect or the second aspect Said method.
  • the embodiment of the present application further provides a computer program product comprising a program, when executed on a computer, causing the computer to perform the method of the first aspect or the second aspect.
  • FIG. 1 is a schematic diagram of an interworking architecture between a 4G system and a 5G system in the embodiment of the present application;
  • FIG. 2 is a flowchart of an overview of a method for selecting a network element in an embodiment of the present application
  • FIG. 3 is a schematic diagram of a specific process of establishing a session connection in a 4G network by the UE in the embodiment of the present application;
  • FIG. 4 is a second schematic flowchart of a process for establishing a session connection in a 4G network by the UE in the embodiment of the present application;
  • FIG. 5 is a schematic diagram of a specific process of establishing a session connection in a 5G network by the UE in the embodiment of the present application;
  • FIG. 6 is a second schematic flowchart of a process for a UE to establish a session connection in a 5G network according to an embodiment of the present application
  • FIG. 7 is a schematic structural diagram of a network element selecting apparatus according to an embodiment of the present application.
  • FIG. 8 is a schematic structural diagram of a first network element in a first communication system according to an embodiment of the present application.
  • FIG. 9 is a third schematic flowchart of a process for a UE to establish a session connection in a 4G network according to an embodiment of the present application.
  • FIG. 10 is a third schematic flowchart of a process for a UE to establish a session connection in a 5G network according to an embodiment of the present application.
  • FIG. 1 is a schematic diagram of a specific application scenario of the embodiment of the present application. It should be understood that FIG. 1 is only an example and is not limited to the present application.
  • the 4G network and the 5G network share a User Plane Function (UPF) + a Packet Data Network Gateway User Plane Function (Packet Data Network Gateway User Plane Function, PGW-U), Session Management Function (SMF)+Protocol Data Unit Gateway Control plane function (PGW-C), Policy Control Function (PCF)+(Policy) And Charging Rules Function (PCRF) policy and charging rules function, Home Subscriber Server (HSS) + Unified Data Management (UDM).
  • UPF User Plane Function
  • PGW-U Packet Data Network Gateway User Plane Function
  • SMF Session Management Function
  • PGW-C Session Management Function
  • PCF Policy Control Function
  • PCF Policy Control Function
  • PCF Policy and Charging Rules Function
  • HSS Home Subscriber Server
  • UDM Unified Data Management
  • the UPF is a 5G user plane function network element
  • the PGW-U is a 4G PDU gateway user plane function network element corresponding to the UPF.
  • the UPF+PGW-U is a combined user plane function network element, and has a 5G system user.
  • SMF is the 5G session management function network element
  • PGW-C is the PDU gateway control plane function network element in 4G corresponding to SMF
  • SMF+PGW-C is the set session Management function network element, with 5G system session management capability and 4G system session management capability
  • PCF is 5G policy and charging rule function network element
  • PCRF is 4G policy control function network element
  • online charging system Online charging system (OCS) and offline charging system (OFCS)
  • PCF+PCRF is a combined policy and charging rule function network element, with 5G system strategy and meter The fee rule function and the policy and charging rule function of the 4G system
  • the UDM is used to manage 5G user data, for example, the 5G user data includes the user's 5G subscription information, and the HSS corresponds to the UDM to manage the 4G user data.
  • 4G user data 4G comprises subscription information of the user, HSS + UDM Joint user data management NE.
  • the Next Generation Radio Access Networks (NG-RAN) in FIG. 1 is a 5G access network device
  • an evolved UMTS Terrestrial Radio Access Network (Evolved UMTS Terrestrial Radio Access Network, E -UTRAN) is a 4G access network device.
  • the MME and the E-UTRAN communicate with the UPF+PGW-U or the SMF+PGW-C through a Serving Gateway (SGW).
  • SGW Serving Gateway
  • the foregoing interworking architecture may also include a simple 4G network element, for example, at least one of PGW-U, PGW-C, PCRF, and HSS.
  • the interworking architecture may also include a simple 5G network element. For example, at least one of UPF, SMF, PCF, and UDM may be included.
  • the AMF Access and Mobility Management Function
  • the AMF determines that the UE can support the 4G system and the 5G system
  • the AMF selects the UE for the UE.
  • the session management function network element establishes a connection.
  • the UE does not need to use the services of the 4G network or the services of the 4G network, that is, the UE supporting the 4G system and the 5G system may not have the interoperability request. Therefore, at this time, the AMF does not need to select a set session management function network element for the UE. Therefore, when the UE accesses the 5G system, there is also a problem that the network element selection is unreasonable.
  • the embodiment of the present application provides a network element selection method.
  • the UE that supports the 4G system and the 5G system and has no interworking requirement selects the network element reasonably.
  • the method includes:
  • Step 200 The first network element in the first communication system receives the first message sent by the terminal device, where the first message is used to request to establish a session.
  • the first message is used to request to establish a session.
  • the first network element determines, according to the message type or message name of the first message, that the message is used to request to establish a session, for example, the first message is a PDU session.
  • a PDU Session Establishment Request or the first message is a PDN Connectivity Request
  • the first network element may determine, according to the message name, that the message is used to request to establish a session, or the first message is an attach request (Attach) Request), the first network element may determine, according to the message type, that the UE needs to request to establish a session after successfully registering on the network side.
  • Step 210 The first network element in the first communication system determines, according to the first subscription information, the target session management function network element according to the first subscription information and the second subscription information, where the first subscription information includes the terminal device in the first communication system.
  • the subscription information includes the subscription information of the terminal device in the second communication system.
  • the first subscription information may be subscription information corresponding to one or more data network identifiers of the terminal device in the first communication system.
  • the second subscription information may also be subscription information corresponding to one or more data network identifiers of the terminal device in the second communication system.
  • the first subscription information may be an indication information indicating whether the terminal device has subscribed to a certain data network identifier in the first communication system
  • the second subscription information may also be an indication information indicating the terminal. Whether the device has signed a certain data network identifier in the second communication system.
  • the first network element in the first communication system needs to acquire the first subscription information and the second subscription information.
  • the first network element in the first communication system sends a third message to the set user data management network element, where the third message is used to obtain the first subscription information and Second signing information.
  • the first network element in the first communication system saves the first subscription information and the second subscription information.
  • the first network element in the first communication system queries the user data management network element in the first communication system for the first subscription information, and queries the user data management network element in the second communication system for the second subscription information. Therefore, the first network element in the first communication system can save the first subscription information and the second subscription information in advance.
  • the first network element in the first communication system sends a fourth message to the set user data management network element, wherein the fourth message is used for The first contract information and the second contract information are queried.
  • the first network element in the first communication system queries the user data management network element in the first communication system for the first subscription information, and queries the user data management network element in the second communication system for the second subscription information. Therefore, the first network element in the first communication system can query the first subscription information and the second subscription information in real time.
  • the combined user data management network element may be an HSS+UDM as shown in FIG. 1.
  • the first network element in the first communication system may further determine the data network identifier of the current session before acquiring the first subscription information and the second subscription information, and then obtain the corresponding data network identifier of the terminal device in the first communication system.
  • the subscription information is used as the first subscription information
  • the subscription information corresponding to the data network identifier corresponding to the data network identifier in the second communication system is obtained as the second subscription information.
  • the application does not limit the order in which the first network element in the first communication system acquires the first subscription information and the second subscription information, that is, the first network element can simultaneously acquire the first subscription information and the second subscription. Information, you can also get the first signing information, and then get the second signing information.
  • the first network element in the first communication system first obtains the first subscription information, and if it is determined that the first subscription information exists, the second subscription information is acquired, and if it is determined that the first subscription information does not exist, The current session establishment request is rejected, and optionally, the second subscription information is no longer obtained.
  • the first network element in the first communication system may determine the target session management function network element according to the terminal device capability, the first subscription information, and the second subscription information.
  • the first network element in the first communication system receives a non-access stratum (NAS) message sent by the terminal device, where the NAS message carries the terminal device capability information.
  • the first message carries terminal device capability information.
  • the terminal device capability information includes information on whether the terminal device supports the first communication system and whether the terminal device supports information of the second communication system, or the terminal device capability information includes an indication of whether the terminal device is the first communication system and the second communication system. information. Therefore, the first network element in the first communication system can determine whether the terminal device supports the first communication system and the second communication system according to the terminal device capability information.
  • the first communication system is a 4G system
  • the second communication system is a 5G system
  • the first network element in the first communication system is an MME.
  • Scenario 1 can specifically include two possible scenarios:
  • the first possible case if the terminal device supports the first communication system and the second communication system, and the first subscription information and the second subscription information both include subscription information corresponding to the data network identifier of the session, the MME selects the set session.
  • the management function network element serves as a target session management network element, such as SMF+PGW-C as shown in FIG.
  • the second possible case is as follows: if the terminal device supports the first communication system and the second communication system, and the first subscription information includes the subscription information corresponding to the data network identifier of the session, and the second subscription information does not include the data network identifier of the session.
  • the subscription information, the MME selects the session management function network element in the 4G system as the target session management network element, for example, PGW-C as shown in FIG.
  • the MME needs to determine the target session management network element by using two determining steps.
  • the application sequence of the two determining steps is not limited in this application:
  • One of the determining steps is whether the terminal device supports the first communication system and the second communication system.
  • the MME may determine, according to the terminal device capability information, that the terminal device supports the first communication system and the second communication system;
  • Another determining step is whether the first subscription information and the second subscription information both include subscription information corresponding to the data network identifier of the session.
  • the MME needs to determine the data network identity of the session.
  • the data network identifier of the session is an Access Point Name (APN).
  • APN Access Point Name
  • the first message carries the data network identifier of the session, and the MME may determine the data network identifier of the session according to the first message.
  • the first message does not carry the data network identifier, and the MME may determine an APN, for example, a default APN, or determine a configured APN for the session according to a local policy or a local configuration.
  • the method for determining the data network identifier of the session by the MME is the same as that here, and the repeated description is not repeated.
  • the MME determines or acquires the first subscription information and the second subscription information according to the determined APN.
  • the first subscription information is the subscription information of the APN of the terminal device in the 4G system, and may also be an indication information. Indicates whether the terminal device has signed the APN.
  • the second subscription information is the subscription information of the data network name (DNN) corresponding to the APN of the terminal device in the 5G system, and may also be an indication information indicating whether the terminal device has signed the DNN, wherein the APN and the DNN
  • the second subscription information is the subscription information of the DNN+Single Network Slice Selection Assistance information (S-NSSAI) corresponding to the APN of the terminal device in the 5G system, and may also be an indication information indicating Whether the terminal device has signed the DNN+S-NSSAI, wherein the APN corresponds to the DNN+S-NSSAI.
  • DNN data network name
  • S-NSSAI DNN+Single Network Slice Selection Assistance information
  • the MME determines that the first subscription information and the second subscription information both include the subscription information corresponding to the data network identifier of the session: the terminal device has the APN subscription information in the 4G system, and the terminal device In the 5G system, there is DNN subscription information corresponding to the APN; or, the terminal device has the APN subscription information in the 4G system, and the terminal device has DNN+S-NSSAI subscription information corresponding to the APN in the 5G system.
  • the MME determines that the first subscription information includes the subscription information corresponding to the data network identifier of the session, and the second subscription information does not include the subscription information corresponding to the data network identifier of the session: the terminal device has the 4G system.
  • the APN subscription information, and the terminal device does not have the DNN subscription information corresponding to the APN in the 5G system; or the terminal device has the APN subscription information in the 4G system, and the terminal device does not have the DNN corresponding to the APN in the 5G system.
  • +S-NSSAI signing information it is worth noting that the DNN+S-NSSAI subscription information in this application refers to the DNN plus S-NSSAI granular subscription information.
  • the DNN+S-NSSAI subscription information mentioned below has the same meaning here, and the repetition is not Let me repeat.
  • the MME first obtains all the subscription information of the terminal device in the 4G system and all the subscription information of the 5G system.
  • the first subscription information includes subscription information corresponding to each APN contracted by the terminal device in the 4G system
  • the second subscription information includes subscription information corresponding to each DNN contracted by the terminal device in the 5G system, or the second subscription information includes the terminal.
  • the MME determines that the first subscription information and the second subscription information both include the subscription information corresponding to the data network identifier of the session: the MME determines that the first subscription information includes the subscription information corresponding to the APN.
  • the second subscription information includes the DNN subscription information corresponding to the APN; or the first subscription information includes the subscription information corresponding to the APN, and the second subscription information includes the DNN+S corresponding to the APN.
  • -NSSAI signing information For the second possibility, the MME determines that the first subscription information includes the subscription information corresponding to the data network identifier of the session, and the second subscription information does not include the subscription information corresponding to the data network identifier of the session: the MME determines the first subscription information.
  • the subscription information corresponding to the APN is included, and the second subscription information does not include the DNN subscription information corresponding to the APN; or the MME determines that the first subscription information includes the subscription information corresponding to the APN, and the second subscription information is included in the second subscription information.
  • the DNN+S-NSSAI subscription information corresponding to the APN is not included.
  • the MME first obtains all the subscription information of the terminal device in the 4G system, where the first subscription information includes subscription information corresponding to each APN contracted by the terminal device in the 4G system, and then the MME determines according to the determined APN. Or obtaining the second subscription information, where the second subscription information is the DNN subscription information corresponding to the APN in the 5G system, or an indication information indicating whether the terminal device has signed the DNN, or the second subscription information is The DNN+S-NSSAI subscription information corresponding to the APN in the 5G system may also be an indication information indicating whether the terminal device has subscribed to the DNN+S-NSSAI.
  • the MME determines that the first subscription information and the second subscription information both include the subscription information corresponding to the data network identifier of the session, where the first subscription information includes the subscription information corresponding to the APN, and The terminal device has the DNN subscription information corresponding to the APN in the 5G system; or the first subscription information includes the subscription information corresponding to the APN, and the terminal device has the DNN+S-NSSAI corresponding to the APN in the 5G system. Signing information.
  • the MME determines that the first subscription information includes the subscription information corresponding to the data network identifier of the session, and the second subscription information does not include the subscription information corresponding to the data network identifier of the session: the first subscription information includes The subscription information corresponding to the APN, and the terminal device does not have the DNN subscription information corresponding to the APN in the 5G system; or the first subscription information includes the subscription information corresponding to the APN, and the terminal device does not have the same in the 5G system.
  • the DNN+S-NSSAI subscription information corresponding to the APN is the first subscription information includes the subscription information corresponding to the data network identifier of the session.
  • not all the subscription information corresponding to each APN included in the first subscription information has one-to-one correspondence with the DNN in the second subscription information, and only a part of the APN subscription information exists in the 5G system.
  • DNN subscription information corresponding to one of the ones is not the subscription information corresponding to each APN included in the first subscription information.
  • the subscription information corresponding to each APN included in the first subscription information has the one-to-one corresponding DNN+S-NSSAI subscription information in the second subscription information, and only a part of the APN subscription information is in the 5G system.
  • the MME sends a fifth message to the set user data management network element, where the fifth message is used.
  • the MME receives the query result sent by the user data management network element, and if the query result indicates that the subscription information corresponding to the APN has the subscription information corresponding to the DNN corresponding to the APN, the MME selects the set session management function network element.
  • the MME selects the session management function network element in the 4G system. Or, if the terminal device supports the first communication system and the second communication system, after the MME determines the APN, the MME sends a fifth message to the set user data management network element, where the fifth message is used to query whether the subscription information corresponding to the APN is There is subscription information corresponding to the DNN+S-NSSAI corresponding to the APN.
  • the MME receives the query result sent by the user data management network element, and if the query result indicates that the subscription information corresponding to the APN has the subscription information corresponding to the DNN+S-NSSAI corresponding to the APN, the MME selects the combined session management.
  • the function network element if the query result indicates that the subscription information corresponding to the APN does not have the subscription information corresponding to the DNN+S-NSSAI corresponding to the APN, the MME selects the session management function network element in the 4G system.
  • the MME sends a sixth message to the set user data management network element, where the sixth message is used to obtain a mapping relationship between the APN and the DNN, where the mapping relationship indicates that the APN subscription information has a corresponding DNN subscription.
  • the MME receives the mapping relationship sent by the user data management network element and saves the mapping relationship. For example, the MME may send the sixth message to the set user data management network element before receiving the first message sent by the terminal device. Or, the MME may send the sixth message to the set user data management network element after receiving the first message sent by the terminal device. After determining the APN, the MME queries the mapping relationship according to the APN.
  • the MME selects a set session management function network element, and if the mapping relationship indicates that the APN does not have a corresponding DNN. Then, the MME selects the session management function network element in the 4G system.
  • the above design also applies to the case where APN corresponds to DNN and S-NSSAI, and will not be described here.
  • the terminal device signs 3 APNs in the 4G system, including APN1, APN2, and APN3, and signs 4 DNNs in the 5G system, including DNN1, DNN2, DNN3, and DNN4, where APN1 corresponds to DNN2, and APN3 corresponds to DNN3.
  • the mapping relationship includes APN1 and DNN2, and APN3 and DNN3. If the MME determines the APN2, the APN is queried according to the APN2 to determine that the corresponding DNN does not exist in the APN2, and the MME selects the session management function network element in the 4G system. If the MME determines the APN3, the APN3 queries the mapping relationship to determine that the APN4 exists. The DNN is DNN3, and the MME selects the set session management function network element.
  • the MME can select the set session management function network element as the target session management function network element for the terminal device having the interworking capability and the interworking requirement.
  • the MME can select the session management function network element in the 4G system as the target session management network element for the terminal device that has the interworking capability but does not have the interworking requirement (that is, the service that does not need to use the 5G network or the service that does not subscribe to the 5G network). Session requirements, and can reduce the load of the combined session management function network element.
  • the first communication system is a 5G system
  • the second communication system is a 4G system
  • the first network element in the first communication system is an AMF.
  • Scenario 2 can specifically include two possible scenarios:
  • the first possible case if the terminal device supports the first communication system and the second communication system, and the first subscription information and the second subscription information both include the subscription information corresponding to the data network identifier of the session, the AMF selects the set session.
  • the management function network element serves as a target session management network element, such as SMF+PGW-C as shown in FIG.
  • the second possible case if the terminal device supports the first communication system and the second communication system, and the first subscription information includes the subscription information corresponding to the data network identifier of the session, the second subscription information does not include the data network identifier corresponding to the session.
  • the AMF selects the session management function network element in the 5G system as the target session management network element, wherein the session management function network element in the 5G communication system is the SMF.
  • the AMF needs to determine the target session management network element through two determining steps, and the execution order of the two determining steps is not limited:
  • a determining step is whether the terminal device supports the first communication system and the second communication system. Specifically, the AMF may determine, according to the terminal device capability information, that the terminal device supports the first communication system and the second communication system;
  • Another determining step is that the AMF determines whether the first subscription information and the second subscription information both include subscription information corresponding to the data network identifier of the session.
  • the AMF determines the data network identity of the current session.
  • the data network identifier of the session is DNN, or DNN and S-NSSAI.
  • the specific method for determining the specific manner of the DNN or the DNN and the S-NSSAI is not limited.
  • the first message carries the data network identifier of the session, and the AMF may determine the data network identifier of the session according to the first message.
  • the first message does not carry the data network identifier
  • the AMF can determine a DNN or DNN and S-NSSAI, for example, a default DNN or DNN and S-NSSAI, or according to local policies or local The configuration, etc., determines a configured DNN or DNN and S-NSSAI for the session.
  • the method for determining the data network identifier of the session by the AMF is the same as that here, and the repeated description will not be repeated.
  • the AMF determines or acquires the first subscription information and the second subscription information according to the determined DNN.
  • the first subscription information is the subscription information of the DNN of the terminal device in the 5G system, and may also be an indication information. , indicating whether the terminal device has signed the DNN.
  • the second subscription information is the APN subscription information corresponding to the DNN of the terminal device in the 4G system, where the APN corresponds to the DNN, or the second subscription information is the APN corresponding to the DNN and the S-NSSAI in the 4G system of the terminal device.
  • the subscription information wherein the APN corresponds to the DNN+S-NSSAI, and may also be an indication message indicating whether the terminal device has subscribed to the APN.
  • the AMF determines that the first subscription information and the second subscription information both include the subscription information corresponding to the data network identifier of the session: the terminal device has the DNN subscription information in the 5G system, and the terminal device There is an APN subscription information corresponding to the DNN in the 4G system; or, the terminal device has the DNN+S-NSSAI subscription information in the 5G system, and the terminal device has an APN corresponding to the DNN+S-NSSAI in the 4G system. Signing information.
  • the AMF determines that the first subscription information includes the subscription information corresponding to the data network identifier of the session, and the second subscription information does not include the subscription information corresponding to the data network identifier of the session: the terminal device has a 5G system.
  • the DNN signing information, and the terminal device does not have the APN subscription information corresponding to the DNN in the 4G system; or the terminal device has the DNN+S-NSSAI subscription information in the 5G system, and the terminal device does not have the same in the 4G system.
  • APN subscription information corresponding to DNN+S-NSSAI is mapped to the terminal device.
  • the AMF first obtains all the subscription information of the terminal device in the 4G system and all the subscription information of the 5G system.
  • the first subscription information includes subscription information corresponding to each DNN contracted by the terminal device in the 5G system, or the first subscription information includes subscription information corresponding to each DNN+S-NSSAI contracted by the terminal device in the 5G system.
  • the second subscription information includes subscription information of each APN contracted by the terminal device in the 4G system.
  • the AMF determines that the first subscription information and the second subscription information both include the subscription information corresponding to the data network identifier of the session: the AMF determines that the first subscription information includes the subscription information corresponding to the DNN.
  • the second subscription information includes the APN subscription information corresponding to the DNN.
  • the AMF determines that the first subscription information includes the subscription information corresponding to the DNN+S-NSSAI, and the second subscription information includes the APN subscription information corresponding to the DNN+S-NSSAI.
  • the AMF determines that the first subscription information includes the subscription information corresponding to the data network identifier of the session, and the second subscription information does not include the subscription information corresponding to the data network identifier of the session: the AMF determines the first subscription information.
  • the subscription information corresponding to the DNN is included, and the second subscription information does not include the APN subscription information corresponding to the DNN.
  • the AMF determines that the first subscription information includes the subscription information corresponding to the DNN+S-NSSAI, and the second subscription information does not include the APN subscription information corresponding to the DNN+S-NSSAI.
  • the AMF first obtains all the subscription information of the terminal device in the 5G system, where the first subscription information includes subscription information of each DNN that the terminal device subscribes to in the 5G system, or the first subscription information includes the terminal device.
  • the AMF determines or acquires the second subscription information according to the determined DNN or the DNN+S-NSSA, where the second subscription information is the APN subscription information corresponding to the DNN or the DNN+S-NSSA in the 4G system, or may be a
  • the indication information indicates whether the terminal device has subscribed to the APN.
  • the AMF determines that the first subscription information and the second subscription information both include the subscription information corresponding to the data network identifier of the session: the first subscription information includes the subscription information corresponding to the DNN, and The terminal device has the APN subscription information corresponding to the DNN in the 4G system; or the first subscription information includes the subscription information corresponding to the DNN+S-NSSAI, and the terminal device has the DNN+S- in the 4G system.
  • the AMF determines that the first subscription information includes the subscription information corresponding to the data network identifier of the session, and the second subscription information does not include the subscription information corresponding to the data network identifier of the session: the first subscription information includes The DNN corresponds to the subscription information, and the terminal device does not have the APN subscription information corresponding to the DNN in the 4G system; or the first subscription information includes the subscription information corresponding to the DNN+S-NSSAI, and the terminal device is in the 4G system. There is no APN subscription information corresponding to the DNN+S-NSSAI.
  • not all the subscription information corresponding to each DNN included in the first subscription information has the subscription information of the APN corresponding to the one-to-one correspondence in the second subscription information, and only a part of the subscription information of the DNN exists in the 4G system.
  • not all the subscription information corresponding to each DNN+S-NSSAI included in the first subscription information has one-to-one corresponding APN subscription information in the second subscription information, and only a part of DNN+S-NSSAI is signed.
  • the information has one-to-one APN subscription information in the 4G system.
  • the AMF sends a seventh message to the set user data management network element, where the seventh message is used for querying. Whether the subscription information corresponding to the DNN has subscription information corresponding to the APN corresponding to the DNN.
  • the AMF receives the query result sent by the user data management network element, and if the query result indicates that the subscription information corresponding to the APN corresponding to the DNN exists, the AMF selects the session management function network element, if the query result indicates If the subscription information corresponding to the DNN does not have subscription information corresponding to the APN corresponding to the DNN, the AMF selects the session management function network element in the 5G system.
  • the AMF determines the DNN+S-NSSAI
  • the AMF sends a seventh message to the set user data management network element, and the seventh message is used to query the DNN+ Whether the subscription information corresponding to the S-NSSAI has APN subscription information corresponding to the DNN+S-NSSAI.
  • the AMF receives the query result sent by the user data management network element, and if the query result indicates that there is the subscription information corresponding to the APN corresponding to the DNN+S-NSSAI, the AMF selects the set session management function network element, if The query result indicates that the subscription information corresponding to the DNN+S-NSSAI does not have the subscription information corresponding to the APN corresponding to the DNN+S-NSSAI, and the AMF selects the session management function network element in the 5G system.
  • the AMF sends an eighth message to the set user data management network element, where the eighth message is used to obtain the mapping between the DNN and the APN. Relationship, the AMF receives the mapping relationship sent by the user data management network element, and saves the mapping relationship. For example, the AMF may send the eighth message to the set user data management network element before receiving the first message sent by the terminal device. Alternatively, the AMF may send an eighth message to the set user data management network element after receiving the first message sent by the terminal device. After determining the DNN, the AMF queries the mapping relationship according to the DNN.
  • the AMF selects the set session management function network element, if the mapping relationship indicates that the DNN does not have a corresponding APN. Then, AMF selects the session management function network element in the 5G system.
  • the above design is also applicable to the case where the DNN+S-NSSAI corresponds to the APN, and details are not described herein again.
  • the terminal device signs 3 APNs in the 4G system, including APN1, APN2, and APN3, and signs 4 DNNs in the 5G system, including DNN1, DNN2, DNN3, and DNN4, where APN1 corresponds to DNN2, and APN3 corresponds to DNN3.
  • the mapping relationship includes APN1 and DNN2, and APN3 and DNN3. If the AMF determines the DNN2, the DNN2 queries the mapping relationship to determine that the corresponding APN of the DNN2 is APN1, and the AMF selects the set session management function network element. If the AMF determines the DNN1, the DNN1 queries the mapping relationship to determine that the DNN1 does not exist. APN, then AMF selects the session management function network element in the 5G system.
  • the AMF may select a set session management function network element as a target session management function network element for a terminal device having interworking capability and interworking requirements.
  • the AMF can select the session management function network element in the 5G system as the target session management network element for the terminal device that has the interworking capability but does not have the interworking requirement (that is, the service that does not need to use the 4G network or the service that does not subscribe to the 4G network). Session requirements, and can reduce the load of the combined session management function network element.
  • the first network element in the first communication system may further determine the second message according to the terminal device capability, the first subscription information, and the second subscription information, and send the second message to the target session management function network element, so that the target session management is performed.
  • the function network element determines the policy control network element and the charging system according to the second message.
  • the second message includes a policy control network element and a charging system indicating that the target session management function network element selects the connection or a policy control network element and a charging system in the first communication system.
  • the first communication system is a 4G system
  • the second communication system is a 5G system
  • the first network element in the first communication system is an MME.
  • the MME selects The MME sends a second message to the set session management function network element, so that the set session management function network element determines the policy control network element and the charging system as the 4G system according to the second message.
  • the policy controls the network element and the billing system.
  • the second message includes the indication information indicating that the set session management function network element selects the policy control network element and the charging system in the 4G system.
  • the MME may indicate, by using the second message, that the set session management function network element is selected in the 4G system for the terminal device that has the interworking capability but does not have the interworking requirement (that is, the service that does not need to use the 5G network or the service that does not sign the 5G network).
  • the policy controls the network element and the charging system to reduce the load of the combined policy control network element and the charging system.
  • the PGW-C is upgraded to SMF+PGW-C, but the policy control network element and the charging system network element are not upgraded, that is, the 4G policy control network element can be a PCRF.
  • the fee system network element can be OCS and OFCS.
  • the MME may send a second message to the SMF+PGW-C, the second message including a policy control network element and a charging system indicating that the information indicates SMF+PGW-C selection and access to 4G.
  • the MME when the MME selects the session management function network element of 4G, the session management function network element of the 4G selects the 4G policy control network element and the charging system, and when the MME selects the set session management function network element The combined session management function network element selects the combined policy control network element and the charging system.
  • the MME can instruct the network element of the session management function to select the policy control network element and the charging system in the 4G system, thereby implementing the mitigation of the policy control network element and the charging system. Load.
  • the first communication system is a 5G system
  • the second communication system is a 4G system
  • the first network element in the first communication system is an AMF.
  • the AMF selects The associated session management function network element, the AMF sends a second message to the set session management function network element, so that the set session management function network element determines the policy control network element and the charging system to be 5G according to the second message.
  • the policy controls the network element and the billing system.
  • the second message includes the indication information indicating that the set session management function network element selects the policy control network element and the charging system in the 5G system.
  • the AMF can indicate, by using the second message, that the set session management function network element selects the terminal device in the 5G system for the terminal device that has the interworking capability but does not have the interworking requirement (that is, the service that does not need to use the 4G network or the service that does not sign the 4G network).
  • the policy controls the network element and the charging system to reduce the load of the combined policy control network element and the charging system.
  • SMF+PGW-C is all upgraded on the PGW-C, but the policy control network element and the charging system are related to the network.
  • the element is not upgraded. Therefore, AMF can only select SMF+PGW-C.
  • AMF sends a second message to SMF+PGW-C.
  • the second message includes the instruction information indicating that SMF+PGW-C selects and accesses the 5G policy control network.
  • Meta and billing systems such as PCF.
  • the AMF selects the 5G session management function network element
  • the 5G session management function network element selects the 5G policy control network element and the charging system
  • the AMF selects the set session management function network element
  • the combined session management function network element selects the combined policy control network element and the charging system.
  • the AMF can instruct the network element of the session management function to select the policy control network element and the charging system in the 5G system, thereby implementing the mitigation of the policy control network element and the charging system. Load.
  • FIG. 3 one of the specific processes for the UE to establish a session connection in a 4G network is shown.
  • Step 301 The MME acquires UE capability information.
  • the UE sends a NAS message to the MME, where the NAS message carries UE capability information, where The UE capabilities include information such as whether the UE supports the 4G system, whether the UE supports the 5G system, or the UE capabilities include indication information of whether the UE supports both the 4G system and the 5G system.
  • the MME saves UE capabilities.
  • Step 302 The UE sends a request session message to the MME, and the request session message may also be included in an attach request.
  • the session request message can be a NAS message.
  • Step 303 The MME determines the APN.
  • the request session message carries the APN.
  • the APN is not carried in the request session message, and the MME may determine an APN, for example, a default APN.
  • Step 304 The MME determines the target session management function network element according to the UE capability information, the first subscription information, and the second subscription information. If the terminal device supports the 4G system and the 5G system, and the first subscription information and the second subscription information both include the subscription information corresponding to the APN, the MME performs step 305a; if the terminal device supports the 4G system and the 5G system, and the first subscription information includes the APN. Corresponding contract information, and the second subscription information does not include the subscription information corresponding to the APN, and the MME performs step 305b. It should be understood that the specific process of determining the target session management function network element by the MME according to the UE capability information, the first subscription information, and the second subscription information may refer to the possible implementation manners in the foregoing scenario 1.
  • the MME before step 302, for example, in an Attach process or a TAU process, the MME sends a third message to the HSS+UDM, wherein the third message is used to obtain the first subscription information and the second subscription information. .
  • the MME saves the first subscription information and the second subscription information.
  • the MME after step 303, the MME sends a fourth message to the HSS+UDM, wherein the fourth message is used to query the first subscription information and the second subscription information.
  • Step 305a The MME selects SMF+PGW-C as the target session management network element, and sends a request session message to the SMF+PGW-C.
  • Step 305b The MME selects the PGW-C as the target session management network element, and sends a request session message to the PGW-C.
  • the subsequent session establishment process mainly includes configuration of a radio resource, establishment of a user plane tunnel, and the like, and may refer to the prior art.
  • the PGW-C is upgraded to SMF+PGW-C, but the network elements of the policy control network element and the charging system are not upgraded.
  • the 4G policy control network element is PCRF
  • the 4G charging system network element is OCS and
  • the OFCS, 5G policy control network element and charging system is PCF.
  • Steps 401 - 403 are the same as steps 301 - 303.
  • Step 404 The MME determines, according to the UE capability information, the first subscription information, and the second subscription information, whether the target policy controls the network element and the charging system. If the terminal device supports the 4G system and the 5G system, and the first subscription information and the second subscription information both include the subscription information corresponding to the APN, the MME performs step 405a; if the terminal device supports the 4G system and the 5G system, and the first subscription information includes the APN. The MME performs step 405b, corresponding to the subscription information, and the second subscription information does not include the subscription information corresponding to the APN.
  • Step 405a The MME sends a request session message to the SMF+PGW-C.
  • the request session message may not carry the indication information or carry the first indication information, and the first indication information indicates that the SMF+PGW-C selects the set policy control network element and the charging system. Therefore, the target policy control network element and the charging system are a combined policy control network element and a charging system.
  • Step 405b The MME sends a request session message to the SMF+PGW-C, where the request session request message carries the second indication information, where the second indication information instructs the SMF+PGW-C to select the 4G policy control network element and the charging system. Therefore, the target policy control network element and the charging system are 4G policy control network elements and charging systems.
  • FIG. 5 one of the specific processes for the UE to establish a session connection in a 5G network is shown.
  • the following is a description of the DNN and the APN as an example.
  • the processing procedure of the DNN+S-NSSAI and the APN is similar, and is not described here.
  • Step 501 The AMF acquires UE capability information.
  • the UE in a registration process or a re-registration process, the UE sends a NAS message to the AMF, where the NAS message carries UE capabilities, where the UE capabilities include the UE.
  • the 4G system is supported, whether the UE supports the 5G system, or the UE capability includes whether the UE supports the indication information of the 4G system and the 5G system at the same time.
  • AMF saves UE capabilities.
  • Step 502 The UE sends a request session message to the AMF, where the session request message is a NAS message.
  • Step 503 The AMF determines the DNN.
  • the request session message carries the DNN.
  • the DNN is not carried in the request session message, and the AMF can determine an APN, for example, a default DNN.
  • Step 504 The AMF determines the target session management function network element according to the UE capability information, the first subscription information, and the second subscription information. If the terminal device supports the 4G system and the 5G system, and the first subscription information and the second subscription information both include the subscription information corresponding to the DNN, the AMF performs step 505a; if the terminal device supports the 4G system and the 5G system, and the first subscription information includes the DNN Corresponding subscription information, and the second subscription information does not include the subscription information corresponding to the DNN, and the AMF performs step 505b.
  • the specific process of determining the target session management function network element by the AMF according to the UE capability information, the first subscription information, and the second subscription information may refer to the possible implementation manners in the foregoing scenario 2, and the repeated description is not repeated.
  • the AMF before step 502, for example, in a Registration process or a Re-registration process, the AMF sends a third message to the HSS+UDM, wherein the third message is used to obtain the first subscription information and the second message. Signing information. The AMF saves the first subscription information and the second subscription information. In another possible design, after step 503, the AMF sends a fourth message to the HSS+UDM, wherein the fourth message is used to query the first subscription information and the second subscription information.
  • Step 505a The AMF selects SMF+PGW-C as the target session management network element, and sends a request session message to the SMF+PGW-C.
  • Step 505b The AMF selects the SMF as the target session management network element, and sends a request session message to the SMF.
  • the subsequent session establishment process mainly includes configuration of a radio resource, establishment of a user plane tunnel, and the like, and may refer to the prior art.
  • the second process of establishing a session connection in a 5G network by the UE is shown.
  • the simple SMF device has not been deployed yet, that is, SMF+PGW-C are all upgraded on the PGW-C, but the network elements of the policy control network element and the charging system are not upgraded, such as 4G policy control.
  • the network element is PCRF
  • the 4G charging system is OCS and OFCS.
  • Steps 601 - 603 are the same as steps 501 - 503.
  • Step 604 The AMF determines the target policy control network element and the charging system according to the UE capability information, the first subscription information, and the second subscription information. If the terminal device supports the 4G system and the 5G system, and the first subscription information and the second subscription information Each includes the subscription information corresponding to the DNN, and the AMF performs step 605a. If the terminal device supports the 4G system and the 5G system, and the first subscription information includes the subscription information corresponding to the DNN, and the second subscription information does not include the subscription information corresponding to the DNN, the AMF performs Step 605b.
  • Step 605a The AMF sends a request session message to the SMF+PGW-C.
  • the request session message may not carry the indication information or carry the first indication information, and the first indication information indicates that the SMF+PGW-C selects the set policy control network element and the charging system. Therefore, the target policy control network element and the charging system are a combined policy control network element and a charging system.
  • Step 605b The AMF sends a request session message to the SMF+PGW-C, where the session request message carries the second indication information, where the second indication information indicates that the SMF+PGW-C selects and accesses the 5G policy control network element and the charging. system. Therefore, the target policy control network element and the charging system are 4G policy control network elements and charging systems.
  • the embodiment of the present application provides a network element selecting apparatus. As shown in FIG. 7, the apparatus 700 includes:
  • the receiving unit 701 is configured to receive a first message sent by the terminal device, where the first message is used to request to establish a session;
  • the processing unit 702 is configured to determine a target session management function network element according to the first subscription information and the second subscription information, where the first subscription information includes the terminal device in the first communication system, in response to the first message
  • the subscription information includes the subscription information of the terminal device in the second communication system.
  • the processing unit 702 is specifically configured to: determine the target session management function network element according to the terminal device capability, the first subscription information, and the second subscription information.
  • the first communication system is a 4G system
  • the second communication system is a 5G system
  • the device is an MME.
  • the processing unit 702 is specifically configured to: if the terminal device supports And the first communication system and the second communication system, and the first subscription information and the second subscription information each include subscription information corresponding to the data network identifier of the session, and then the selected session management function network element is selected.
  • the target session management network element the network management element having the session management capability of the 5G system and the session management capability of the 4G system is a combined session management function network element.
  • the first communication system is a 4G system
  • the second communication system is a 5G system
  • the device is an MME.
  • the processing unit 702 is specifically configured to: if the terminal device supports The first communication system and the second communication system, and the first subscription information includes subscription information corresponding to the data network identifier of the session, and the second subscription information does not include a data network identifier corresponding to the session.
  • the session management function network element in the 4G system is selected as the target session management network element.
  • the first communication system is a 5G system
  • the second communication system is a 4G system
  • the device is an AMF.
  • the processing unit 702 is specifically configured to: if the terminal device supports And the first communication system and the second communication system, and the first subscription information and the second subscription information each include subscription information corresponding to the data network identifier of the session, and then the selected session management function network element is selected.
  • the target session management network element the network management element having the session management capability of the 5G system and the session management capability of the 4G system is a combined session management function network element.
  • the first communication system is a 5G system
  • the second communication system is a 4G system
  • the device is an AMF.
  • the processing unit 702 is specifically configured to: if the terminal device supports The first communication system and the second communication system, and the first subscription information includes subscription information corresponding to the data network identifier of the session, and the second subscription information does not include a subscription corresponding to the data network identifier of the session.
  • the session management function network element in the 5G system is selected as the target session management network element.
  • the method further includes: a sending unit 703, configured to send, to the target session management function network element, a second message, so that the target session management function network element determines policy control according to the second message Network element and billing system.
  • each unit above is only a division of logical functions, and the actual implementation may be integrated into one physical entity in whole or in part, or may be physically separated.
  • these units may all be implemented in the form of software by means of processing component calls; they may all be implemented in the form of hardware, and some units may be implemented in software in the form of processing component calls, and some units are implemented in hardware.
  • each step of the above method or each of the above units may be completed by an integrated logic circuit of hardware in the processor element or an instruction in a form of software.
  • the above units may be one or more integrated circuits configured to implement the above methods, such as one or more Application Specific Integrated Circuits (ASICs), or one or more microprocessors (digital) Signal processor, DSP), or one or more Field Programmable Gate Arrays (FPGAs).
  • ASICs Application Specific Integrated Circuits
  • DSP digital signal processor
  • FPGAs Field Programmable Gate Arrays
  • the processing element can be a general purpose processor, such as a central processing unit (CPU) or other processor that can invoke the program.
  • CPU central processing unit
  • these units can be integrated and implemented in the form of a system-on-a-chip (SOC).
  • SOC system-on-a-chip
  • the embodiment of the present application provides a network element selecting apparatus.
  • it may be a chip, and the apparatus includes a processor and an interface, and the interface may be an input/output interface.
  • the processor completes the functions of the processing unit 702, and the interface completes the functions of the receiving unit 701 and the sending unit 702.
  • the apparatus can also include a memory for storing a program executable on the processor, which when executed by the processor implements the method of the embodiment shown in FIG.
  • the embodiment of the present application further provides a first network element in the first communication system.
  • the network element 800 includes: a transceiver 801, a processor 802, and a memory 803.
  • the memory 803 is used to store a computer program; the processor 802 calls a computer program stored in the memory 803, and the method shown in FIG. 2 is executed by the transceiver 801.
  • the processor may be a CPU, a network processor (NP), a hardware chip, or any combination thereof.
  • the memory may include a volatile memory such as a random access memory (RAM), or may include a non-volatile memory such as a read-only memory. ROM), flash memory, hard disk drive (HDD) or solid-state drive (SSD), the memory may also include a combination of the above types of memories.
  • the foregoing apparatus in the embodiment shown in FIG. 7 can be implemented by the network element 800 shown in FIG. 8.
  • the processing unit 702 can be implemented by the processor 802
  • the receiving unit 701 and the sending unit 703 can be implemented by the transceiver 801.
  • the structure of the network element 800 does not constitute a limitation on the embodiments of the present application.
  • FIG. 9 one of the specific processes for the UE to establish a session connection in a 4G network is shown.
  • Step 901 The MME acquires UE capability information.
  • the UE sends a NAS message to the MME, where the NAS message carries UE capability information, where The UE capabilities include information such as whether the UE supports the 4G system, whether the UE supports the 5G system, or the UE capabilities include indication information of whether the UE supports both the 4G system and the 5G system.
  • the MME saves UE capabilities.
  • Step 902 The UE sends a request session message to the MME, and the request session message may also be included in an attach request.
  • the session request message can be a NAS message.
  • Step 903 The MME determines the APN.
  • the request session message in step 902 carries the APN.
  • the APN is not carried in the request session message, and the MME may determine an APN, for example, a default APN. The manner of determining the APN is as described above and will not be described again.
  • Step 904 The MME determines the target session management function network element according to the UE capability information (or terminal capability) and the third subscription information. Specifically, if the terminal capability indicates that the UE supports the 4G system and the 5G system, the third subscription of the terminal indicates that the data network identifier APN corresponding to the session supports interworking with the 5G system (or 5GC), and the MME selects The session management function network element is configured as the target session management network element, and step 905a is performed.
  • the terminal capability indicates that the UE supports the 4G system and the 5G system
  • the third subscription of the terminal indicates that the data network identifier APN corresponding to the session supports interworking with the 5G system (or 5GC)
  • the MME selects
  • the session management function network element is configured as the target session management network element, and step 905a is performed.
  • the third subscription of the terminal indicates that the data network identifier of the session corresponds to the APN support and the 5G system (or 5GC) interworking further includes: the third subscription information of the terminal is an indication information indicating the session
  • the corresponding data network identifier APN supports interworking with a certain DNN and a certain network slice identifier S-NSSAI.
  • the set session management function network element may be a network element that has both the session management capability of the 4G system and the session management capability of the 5G system, such as SMF+PGW-C.
  • the MME does not select a combined session management function network.
  • the element is used as the target session management network element, and step 905b is performed.
  • the MME does not select the associated session management function network element as the target session management network element, and the MME selects, as the target session management network element, a session management function network element that is not used for interworking. For example, a PGW-C or PGW in a simple 4G system. Therefore, the MME may select the set session management function network element as the target session management function network element for the terminal device having the interworking capability and the interworking requirement.
  • the MME may further determine the second message according to the terminal device capability and the third subscription information, and send the second message to the target session management function network element, so that the target session management function network element determines the policy control network element and the meter according to the second message.
  • the second message includes a policy control network element and a charging system indicating that the target session management function network element selects a set or a policy control network element and a charging system in the first communication system.
  • Step 905a The MME selects SMF+PGW-C as the target session management network element, and sends a request session message to the SMF+PGW-C.
  • Step 905b The MME selects the PGW-C as the target session management network element, and sends a request session message to the PGW-C.
  • the subsequent session establishment process mainly includes configuration of a radio resource, establishment of a user plane tunnel, and the like, and may refer to the prior art.
  • the MME can select the session management function network element in the 4G system as the target session management network element for the terminal device that has the interworking capability but does not have the interworking requirement (that is, does not support interworking with the 5G), so that the session requirement can be met, and the Set the session management function to load the network element.
  • the MME may indicate that the set session management network element selects a policy control network element and a charging system in the 4G system for the terminal device that has the interworking capability but does not have the interworking requirement (that is, does not support interworking with the 5G), thereby further reducing The combined policy controls the load of the network element and the billing system.
  • the logical structure of the MME in FIG. 9 can be as shown in FIG. 7, and the steps described in FIG. 9 can be implemented by the processing unit, the receiving unit, and the transmitting unit in FIG. It can be understood that the foregoing apparatus in the embodiment shown in FIG. 7 can be implemented by the network element 800 shown in FIG. 8. Specifically, the processing unit 702 can be implemented by the processor 802, and the receiving unit 701 and the sending unit 703 can be implemented by the transceiver 801.
  • the structure of the network element 800 does not constitute a limitation on the embodiments of the present application.
  • FIG. 10 one of the specific processes for the UE to establish a session connection in a 5G network is shown.
  • Step 1001 The AMF acquires UE capability information.
  • the UE in a registration process or a re-registration process, the UE sends a NAS message to the AMF, where the NAS message carries UE capabilities, where the UE capabilities include the UE.
  • the 4G system is supported, whether the UE supports the 5G system, or the UE capability includes whether the UE supports the indication information of the 4G system and the 5G system at the same time.
  • AMF saves UE capabilities.
  • Step 1002 The UE sends a request session message to the AMF, where the session request message is a NAS message.
  • Step 1003 The AMF determines the DNN.
  • the request session message in step 1002 carries the DNN.
  • the DNN is not carried in the request session message, and the AMF can determine an APN, for example, a default DNN.
  • the way to determine the DNN is as described above and will not be described again.
  • Step 1004 The AMF determines the target session management function network element according to the UE capability information (or terminal capability) and the third subscription information. Specifically, if the terminal capability indicates that the UE supports the 4G system and the 5G system, the third subscription of the terminal indicates that the data network identifier DNN corresponding to the session supports interworking with the 4G system (or EPS, or EPC), The AMF selects the associated session management function network element as the target session management network element, and performs step 1005a.
  • the terminal capability indicates that the UE supports the 4G system and the 5G system
  • the third subscription of the terminal indicates that the data network identifier DNN corresponding to the session supports interworking with the 4G system (or EPS, or EPC)
  • the AMF selects the associated session management function network element as the target session management network element, and performs step 1005a.
  • the third subscription of the terminal indicates that the data network identifier DNN corresponding to the session and the 4G system (or EPS, or EPC) intercommunication further include: the third subscription information of the terminal is an indication information, indicating The data network identifier DNN corresponding to the session and the network slice identifier S-NSSAI support interworking.
  • the set session management function network element may be a network element that has both the session management capability of the 4G system and the session management capability of the 5G system, such as SMF+PGW-C.
  • the AMF does not select a combined session management function network.
  • the element is used as the target session management network element, and step 1005b is performed.
  • the AMF does not select the associated session management function network element as the target session management network element, and the AMF selects a session management function network element that is not used for interworking, as the target session management network element. For example, a simple 5G system SMF. Therefore, the AMF can select the set session management function network element as the target session management function network element for the terminal device having the interworking capability and the interworking requirement.
  • the AMF may further determine the second message according to the terminal device capability and the third subscription information, and send the second message to the target session management function network element, so that the target session management function network element determines the policy control network element and the meter according to the second message.
  • the second message includes a policy control network element and a charging system indicating that the target session management function network element selects a set or a policy control network element and a charging system in the first communication system.
  • Step 1005a The AMF selects SMF+PGW-C as the target session management network element, and sends a request session message to the SMF+PGW-C.
  • Step 1005b The AMF selects the SMF as the target session management network element, and sends a request session message to the SMF.
  • the subsequent session establishment process mainly includes configuration of a radio resource, establishment of a user plane tunnel, and the like, and may refer to the prior art.
  • the AMF can select the session management function network element in the 5G system as the target session management network element for the terminal device that has the interworking capability but does not have the interworking requirement (that is, does not support the interworking with the 4G), so that the session requirement can be satisfied, and the session can be reduced.
  • the AMF may indicate that the set session management network element selects a policy control network element and a charging system in the 5G system for the terminal device that has the interworking capability but does not have the interworking requirement (that is, does not support interworking with the 4G), thereby further reducing
  • the combined policy controls the load of the network element and the billing system.
  • the logical structure of the AMF in FIG. 10 can be as shown in FIG. 7, and the steps described in FIG. 10 can be implemented by the processing unit, the receiving unit, and the transmitting unit in FIG. It can be understood that the foregoing apparatus in the embodiment shown in FIG. 7 can be implemented by the network element 800 shown in FIG. 8. Specifically, the processing unit 702 can be implemented by the processor 802, and the receiving unit 701 and the sending unit 703 can be implemented by the transceiver 801.
  • the structure of the network element 800 does not constitute a limitation on the embodiments of the present application.
  • the embodiment of the present application further provides a computer readable storage medium, where the computer readable storage medium stores a computer program, and when the computer program runs on a computer, causes the computer to execute the method of the embodiment shown in FIG.
  • the processor is caused to perform the steps corresponding to the MME as shown in FIG. 9; the processor may also be caused to perform the steps corresponding to the AMF as shown in FIG.
  • the first network element in the first communication system receives the first message sent by the terminal device, where the first message is used to request to establish a session, in response to the first message, by using the method provided by the embodiment of the present application.
  • the first network element in the first communication system determines the target session management function network element according to the first subscription information and the second subscription information, and selects the network element according to whether the terminal device supports the 4G system and the 5G system according to the prior art.
  • the terminal device supporting the 4G system and the 5G system and having no interworking requirements can reasonably select the network element, and can reduce the load of the combined session management function network element.
  • the MME may select a set for the terminal device that has the interworking capability and has the interworking requirement.
  • the session management function network element is the target session management function network element.
  • the MME can select the session management function network element in the 4G system as the target session management network element for the terminal device that has the interworking capability but does not have the interworking requirement (that is, the service that does not need to use the 5G network or the service that does not subscribe to the 5G network). Session requirements, and can reduce the load of the combined session management function network element.
  • the AMF can select a combined session management for a terminal device having interworking capability and having interworking requirements.
  • the function network element is the target session management function network element.
  • the AMF can select the session management function network element in the 5G system as the target session management network element for the terminal device that has the interworking capability but does not have the interworking requirement (that is, the service that does not need to use the 4G network or the service that does not subscribe to the 4G network). Session requirements, and can reduce the load of the combined session management function network element.
  • the MME may indicate that the set session management function network element has the interworking capability through the second message.
  • the terminal device that does not have the interworking requirement that is, the service that does not need to use the 5G network or the service that does not sign the 5G network
  • the AMF may indicate that the set session management function network element has the interworking capability through the second message.
  • the terminal device that does not have the interworking requirement that is, the service that does not need to use the 4G network or the service that does not subscribe to the 4G network
  • embodiments of the present application can be provided as a method, system, or computer program product. Therefore, the embodiments of the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Moreover, embodiments of the present application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) including computer usable program code.
  • computer-usable storage media including but not limited to disk storage, CD-ROM, optical storage, etc.
  • Embodiments of the present application are described with reference to flowchart illustrations and/or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present application. It will be understood that each flow and/or block of the flowchart illustrations and/or FIG.
  • These computer program instructions can be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing device to produce a machine for the execution of instructions for execution by a processor of a computer or other programmable data processing device.
  • the computer program instructions can also be stored in a computer readable memory that can direct a computer or other programmable data processing device to operate in a particular manner, such that the instructions stored in the computer readable memory produce an article of manufacture comprising the instruction device.
  • the apparatus implements the functions specified in one or more blocks of a flow or a flow and/or block diagram of the flowchart.
  • These computer program instructions can also be loaded onto a computer or other programmable data processing device such that a series of operational steps are performed on a computer or other programmable device to produce computer-implemented processing for execution on a computer or other programmable device.
  • the instructions provide steps for implementing the functions specified in one or more of the flow or in a block or blocks of a flow diagram.

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Abstract

本申请公开了一种网元选择方法及装置，该方法包括：第一通信系统中的第一网元接收终端设备发送的第一消息，响应于第一消息，第一通信系统中的第一网元根据第一签约信息和第二签约信息确定目标会话管理功能网元。上述方法可以实现支持4G系统和5G系统且没有互通需求的终端设备合理选择网元。

Description

一种网元选择方法及装置
本申请要求了2018年5月8日提交的、申请号为201810432656.9、发明名称为“一种网元选择方法及装置”的中国申请的优先权，以及2018年5月18日提交的、申请号为201810481106.6、发明名称为“一种网元选择方法及装置”的中国申请的优先权,其全部内容通过引用结合在本申请中。
技术领域
本申请涉及无线通信技术领域，特别涉及一种网元选择方法及装置。
背景技术
随着通信技术的快速发展，第五代(Fifth Generation，5G)移动通信技术应运而生。在网络部署初期，由于5G网络覆盖不足，因此，当用户设备(User Equipment，UE)的位置发生变化时，UE需要在5G网络和第四代(Fourth Generation，4G)网络之间切换会话。
现有技术中，如图1所示，当UE在4G系统接入时，如果移动性管理实体(Mobility Management Entity，MME)确定UE能够支持4G系统和5G系统，则MME为该UE选择合设的会话管理功能网元建立连接。但是，在某些场景下，UE并不需要使用5G网络的服务或没有签约5G网络的服务，即支持4G系统和5G系统的UE并没有互通需求，因此，此时MME并不需要为该UE选择合设的会话管理功能网元。
因此，上述情况存在网元选择不合理的问题，且可能导致合设的会话管理功能网元的负载较重。
发明内容
本申请实施例提供一种网元选择方法及装置，用以实现支持4G系统和5G系统且没有互通需求的UE合理选择网元。
第一方面，本申请提供一种网元选择方法，该方法包括：
第一通信系统中的第一网元接收终端设备发送的第一消息，所述第一消息用于请求建立会话；响应于所述第一消息，所述第一通信系统中的第一网元根据第一签约信息和第二签约信息确定目标会话管理功能网元，所述第一签约信息包括所述终端设备在所述第一通信系统的签约信息，所述第二签约信息包括所述终端设备在第二通信系统中的签约信息。
因此，第一通信系统中的第一网元可以根据第一签约信息和第二签约信息选择合适的网元作为目标会话管理功能网元，相较于现有技术中仅根据终端设备是否支持4G系统和5G系统选择网元，可以实现支持4G系统和5G系统且没有互通需求的终端设备合理地选择网元，且可以减轻合设的会话管理功能网元的负载。
可选地，第一签约信息可以是终端设备在第一通信系统的一个或多个数据网络标识所对应的签约信息。第二签约信息也可以是终端设备在第二通信系统的一个或多个数据网络标识所对应的签约信息。或者，第一签约信息可以是一个指示信息，指示终端设备在第一通信系统中是否签约了某个数据网络标识，第二签约信息也可以是一个指示信息，指示终端设备在第二通信系统中是否签约了某个数据网络标识。
在一种可能的设计中，所述第一通信系统中的第一网元根据第一签约信息和第二签约信息确定目标会话管理功能网元，具体可以根据所述终端设备能力、所述第一签约信息和所述第二签约信息确定所述目标会话管理功能网元。
因此，第一通信系统中的第一网元可以结合终端设备能力，以及第一签约信息和第二签约信息确定目标会话管理功能网元。
在一种可能的设计中，所述第一通信系统为4G系统，所述第二通信系统为5G系统，所述第一通信系统中的第一网元为MME。所述第一通信系统中的第一网元在根据所述终端设备能力、所述第一签约信息和所述第二签约信息确定所述目标会话管理功能网元时，若所述终端设备支持所述第一通信系统和第二通信系统，且所述第一签约信息和所述第二签约信息均包括所述会话的数据网络标识对应的签约信息，则所述MME选择合设的会话管理功能网元作为所述目标会话管理网元，其中，具备5G系统的会话管理能力以及具备4G系统的会话管理能力的网元为合设的会话管理功能网元。
因此，MME可以为有互通能力且有互通需求的终端设备选择合设的会话管理功能网元为目标会话管理功能网元。
在一种可能的设计中，所述第一通信系统为4G系统，所述第二通信系统为5G系统，所述第一通信系统中的第一网元为MME。所述第一通信系统中的第一网元在根据所述终端设备能力、所述第一签约信息和所述第二签约信息确定所述目标会话管理功能网元时，若所述终端设备支持所述第一通信系统和第二通信系统，且所述第一签约信息包括所述会话的数据网络标识对应的签约信息，且所述第二签约信息不包括所述会话的数据网络标识对应的签约信息，则所述MME选择所述4G系统中的会话管理功能网元作为所述目标会话管理网元。
因此，MME可以为有互通能力但没有互通需求(即不需要使用5G网络的服务或没有签约5G网络的服务)的终端设备选择4G系统中的会话管理功能网元作为目标会话管理网元，就能够满足会话需求，进而可以减轻合设的会话管理功能网元的负载。
在一种可能的设计中，所述第一通信系统为5G系统，所述第二通信系统为4G系统，所述第一通信系统中的第一网元为AMF。所述第一通信系统中的第一网元在根据所述终端设备能力、所述第一签约信息和所述第二签约信息确定所述目标会话管理功能网元时，若所述终端设备支持所述第一通信系统和第二通信系统，且所述第一签约信息和所述第二签约信息均包括所述会话的数据网络标识对应的签约信息，则所述AMF选择合设的会话管理功能网元作为所述目标会话管理网元，其中，具备5G系统的会话管理能力以及具备4G系统的会话管理能力的网元为合设的会话管理功能网元。
因此，AMF可以为有互通能力且有互通需求的终端设备选择合设的会话管理功能网元为目标会话管理功能网元。
在一种可能的设计中，所述第一通信系统为5G系统，所述第二通信系统为4G系统，所述第一通信系统中的第一网元为AMF。所述第一通信系统中的第一网元在根据所述终端设备能力、所述第一签约信息和所述第二签约信息确定所述目标会话管理功能网元时，若所述终端设备支持所述第一通信系统和第二通信系统，且所述第一签约信息包括所述会话的数据网络标识对应的签约信息，所述第二签约信息不包括所述会话的数据网络标识对应的签约信息，则所述AMF选择所述5G系统中的会话管理功能网元作为所述目标会话管理网元。
因此，AMF可以为有互通能力但没有互通需求(即不需要使用4G网络的服务或没有 签约4G网络的服务)的终端设备选择5G系统中的会话管理功能网元作为目标会话管理网元，就能够满足会话需求，进而可以减轻合设的会话管理功能网元的负载。
在一种可能的设计中，所述方法还包括：所述第一通信系统中的第一网元向所述目标会话管理功能网元发送第二消息，以使得所述目标会话管理功能网元根据所述第二消息确定策略控制网元和计费系统。
可选地，第二消息中包括指示信息指示目标会话管理功能网元选择合设的策略控制网元和计费系统或者第一通信系统中的策略控制网元和计费系统。当第一通信系统为4G系统，第二通信系统为5G系统，第一通信系统中的第一网元为MME时，MME可以通过第二消息指示合设的会话管理功能网元为有互通能力但没有互通需求(即不需要使用5G网络的服务或没有签约5G网络的服务)的终端设备选择4G系统中的策略控制网元和计费系统，进而可以减轻合设的策略控制网元和计费系统的负载。当第一通信系统为5G系统，第二通信系统为4G系统，第一通信系统中的第一网元为AMF时，AMF可以通过第二消息指示合设的会话管理功能网元为有互通能力但没有互通需求(即不需要使用4G网络的服务或没有签约4G网络的服务)的终端设备选择5G系统中的策略控制网元和计费系统，进而可以减轻合设的策略控制网元和计费系统的负载。
第二方面，本申请提供了另一一种网元选择方法，该方法包括：
第一通信系统中的第一网元接收终端设备发送的第一消息，所述第一消息用于请求建立会话；响应于所述第一消息，所述第一通信系统中的第一网元根据所述终端设备能力和所述终端的第三签约信息确定目标会话管理功能网元。
因此，第一通信系统中的第一网元可以根据所述终端的第三签约信息选择合适的网元作为目标会话管理功能网元，相较于现有技术中仅根据终端设备是否支持4G系统和5G系统选择网元，可以实现支持4G系统和5G系统且没有互通需求的终端设备合理地选择网元，且可以减轻合设的会话管理功能网元的负载。
在一种可能的设计中，所述第一通信系统为4G系统，所述第二通信系统为5G系统，所述第一通信系统中的第一网元为MME。所述终端的第三签约信息可以是一个指示信息，指示所述会话对应的数据网络标识APN是否支持和5G系统(或称为5GC)互通。可选的，所述指示所述会话对应的数据网络标识APN是否支持和5G系统(或称为5GC)互通还包括：终端的第三签约信息是一个指示信息，指示所述会话对应的数据网络标识APN是否支持和某个DNN以及某个网络切片标识S-NSSAI互通。所述第一通信系统中的第一网元根据所述终端设备能力和所述终端的第三签约信息确定目标会话管理功能网元，包括：若所述终端设备支持所述第一通信系统和第二通信系统，且所述终端的第三签约信息指示所述会话对应的数据网络标识APN支持和5G系统互通，则所述MME选择合设的会话管理功能网元作为所述目标会话管理网元。其中，合设的会话管理功能网元可以为同时具备4G系统的会话管理能力以及5G系统的会话管理能力的网元，比如SMF+PGW-C。，因此，MME可以为有互通能力且有互通需求的终端设备选择合设的会话管理功能网元为目标会话管理功能网元。
在一种可能的设计中，所述第一通信系统为4G系统，所述第二通信系统为5G系统，所述第一通信系统中的第一网元为MME。所述终端的第三签约信息可以是一个指示信息，指示所述会话对应的数据网络标识APN是否支持和5G系统(或称为5GC)互通。可选的，所述指示所述会话对应的数据网络标识APN是否支持和5G系统(或称为5GC)互通还包括：终端的第三签约信息是一个指示信息，指示所述会话对应的数据网络标识APN是否 支持和某个DNN以及某个网络切片标识S-NSSAI互通。所述第一通信系统中的第一网元根据所述终端设备能力和所述终端的第三签约信息确定目标会话管理功能网元，包括：若所述终端设备支持所述第一通信系统和第二通信系统，且所述第三签约信息指示所述会话的数据网络标识APN不支持和5G系统互通，则所述MME不选择合设的会话管理功能网元作为所述目标会话管理网元。所述MME不选择合设的会话管理功能网元作为所述目标会话管理网元，包括：所述MME选择一个不是用于专门做互通的会话管理功能网元作为所述目标会话管理网元。因此，MME可以为有互通能力但没有互通需求(即不支持与5G互通的APN)的终端设备选择4G系统中的会话管理功能网元作为目标会话管理网元，就能够满足会话需求，进而可以减轻合设的会话管理功能网元的负载。
在一种可能的设计中，所述第一通信系统为5G系统，所述第二通信系统为4G系统，所述第一通信系统中的第一网元为AMF。所述终端的第三签约信息可以是一个指示信息，指示所述会话对应的数据网络标识DNN是否支持和4G系统(或称为EPS)互通。可选的，所述指示所述会话对应的数据网络标识DNN是否支持和4G系统(或称为EPS)互通还包括：终端的第三签约信息是一个指示信息，指示所述会话对应的数据网络标识DNN和网络切片标识S-NSSAI是否支持和4G(或称为EPS)互通。所述第一通信系统中的第一网元根据所述终端设备能力和所述终端的第三签约信息确定目标会话管理功能网元，包括：若所述终端设备支持所述第一通信系统和第二通信系统，且所述终端的第三签约信息指示所述会话对应的数据网络标识DNN支持和4G系统(或称为EPS)互通，则所述AMF选择合设的会话管理功能网元作为所述目标会话管理网元。其中，合设的会话管理功能网元可以为同时具备5G系统的会话管理能力以及4G系统的会话管理能力的网元，比如SMF+PGW-C。，因此，AMF可以为有互通能力且有互通需求的终端设备选择合设的会话管理功能网元为目标会话管理功能网元。
在一种可能的设计中，所述第一通信系统为5G系统，所述第二通信系统为4G系统，所述第一通信系统中的第一网元为AMF。所述终端的第三签约信息可以是一个指示信息，指示所述会话对应的数据网络标识DNN是否支持和4G系统(或称为EPS)互通。可选的，所述指示所述会话对应的数据网络标识DNN是否支持和4G系统(或称为EPS)互通还包括：终端的第三签约信息是一个指示信息，指示所述会话对应的数据网络标识DNN和网络切片标识S-NSSAI是否支持和4G(或称为EPS)互通。所述第一通信系统中的第一网元根据所述终端设备能力和所述终端的第三签约信息确定目标会话管理功能网元，包括：若所述终端设备支持所述第一通信系统和第二通信系统，且所述第三签约信息指示所述会话的数据网络标识DNN不支持和4G系统互通，则所述AMF不选择合设的会话管理功能网元作为所述目标会话管理网元。所述AMF不选择合设的会话管理功能网元作为所述目标会话管理网元，包括：所述AMF选择一个不是用于专门做互通的会话管理功能网元作为所述目标会话管理网元。因此，AMF可以为有互通能力但没有互通需求(即不支持与4G互通的DNN)的终端设备选择5G系统中的会话管理功能网元作为目标会话管理网元，就能够满足会话需求，进而可以减轻合设的会话管理功能网元的负载。
在一种可能的设计中，所述方法还包括：所述第一通信系统中的第一网元向所述目标会话管理功能网元发送第二消息，以使得所述目标会话管理功能网元根据所述第二消息确定策略控制网元和计费系统。
可选地，第二消息中包括指示信息指示目标会话管理功能网元选择合设的策略控制 网元和计费系统或者第一通信系统中的策略控制网元和计费系统。当第一通信系统为4G系统，第二通信系统为5G系统，第一通信系统中的第一网元为MME时，MME可以通过第二消息指示合设的会话管理功能网元为有互通能力但没有互通需求(即不需要使用5G网络的服务或没有签约5G网络的服务)的终端设备选择4G系统中的策略控制网元和计费系统，进而可以减轻合设的策略控制网元和计费系统的负载。当第一通信系统为5G系统，第二通信系统为4G系统，第一通信系统中的第一网元为AMF时，AMF可以通过第二消息指示合设的会话管理功能网元为有互通能力但没有互通需求(即不需要使用4G网络的服务或没有签约4G网络的服务)的终端设备选择5G系统中的策略控制网元和计费系统，进而可以减轻合设的策略控制网元和计费系统的负载。
第三方面，一种网元选择装置，该装置包括：接收单元，用于接收终端设备发送的第一消息，所述第一消息用于请求建立会话；处理单元，用于响应于所述第一消息，根据第一签约信息和第二签约信息确定目标会话管理功能网元，所述第一签约信息包括所述终端设备在所述第一通信系统的签约信息，所述第二签约信息包括所述终端设备在第二通信系统中的签约信息。
在一种可能的设计中，所述处理单元，具体用于：根据所述终端设备能力、所述第一签约信息和所述第二签约信息确定所述目标会话管理功能网元。
在一种可能的设计中，所述第一通信系统为4G系统，所述第二通信系统为5G系统，所述装置为MME；所述处理单元，具体用于：若所述终端设备支持所述第一通信系统和第二通信系统，且所述第一签约信息和所述第二签约信息均包括所述会话的数据网络标识对应的签约信息，则选择合设的会话管理功能网元作为所述目标会话管理网元，其中，具备5G系统的会话管理能力以及具备4G系统的会话管理能力的网元为合设的会话管理功能网元。
在一种可能的设计中，所述第一通信系统为4G系统，所述第二通信系统为5G系统，所述装置为MME；所述处理单元，具体用于：若所述终端设备支持所述第一通信系统和第二通信系统，且所述第一签约信息包括所述会话的数据网络标识对应的签约信息，且所述第二签约信息不包括所述会话的数据网络标识对应的签约信息，则选择所述4G系统中的会话管理功能网元作为所述目标会话管理网元。
在一种可能的设计中，所述第一通信系统为5G系统，所述第二通信系统为4G系统，所述装置为AMF；所述处理单元，具体用于：若所述终端设备支持所述第一通信系统和第二通信系统，且所述第一签约信息和所述第二签约信息均包括所述会话的数据网络标识对应的签约信息，则选择合设的会话管理功能网元作为所述目标会话管理网元，其中，具备5G系统的会话管理能力以及具备4G系统的会话管理能力的网元为合设的会话管理功能网元。
在一种可能的设计中，所述第一通信系统为5G系统，所述第二通信系统为4G系统，所述装置为AMF；所述处理单元，具体用于：若所述终端设备支持所述第一通信系统和第二通信系统，且所述第一签约信息包括所述会话的数据网络标识对应的签约信息，所述第二签约信息不包括所述会话的数据网络标识对应的签约信息，则择所述5G系统中的会话管理功能网元作为所述目标会话管理网元。
在一种可能的设计中，还包括：发送单元，用于向所述目标会话管理功能网元发送第二消息，以使得所述目标会话管理功能网元根据所述第二消息确定策略控制网元和计费系统。
本发明第四方面公开了另一种网元选择的装置，该装置包括：
接收单元，用于接收终端设备发送的第一消息，所述第一消息用于请求建立会话；
处理单元，用于响应于所述第一消息，根据所述终端设备能力和所述终端的第三签约信息确定目标会话管理功能网元。
在一种可能的实现方式中，第一通信系统为5G系统，第二通信系统为4G系统，所述网元选择装置为5G系统中的接入和移动性管理功能网元AMF，
所述处理单元，具体用于若所述终端设备支持所述第一通信系统和第二通信系统，且所述终端的第三签约信息指示所述会话对应的数据网络标识DNN支持和4G系统互通，则选择合设的会话管理功能网元作为所述目标会话管理网元。
在一种可能的实现方式中，第一通信系统为5G系统，第二通信系统为4G系统，所述网元选择装置为5G系统中的接入和移动性管理功能网元AMF，
所述处理单元，具体用于若所述终端设备支持所述第一通信系统和第二通信系统，且所述第三签约信息指示所述会话的数据网络标识DNN不支持和4G系统互通，则不选择合设的会话管理功能网元作为所述目标会话管理网元。具体的，所述不选择合设的会话管理功能网元作为所述目标会话管理网元，包括：选择所述5G系统中的会话管理功能网元作为所述目标会话管理网元。
在一种可能的实现方式中，第一通信系统为4G系统，第二通信系统为5G系统，所述网元选择的装置为4G系统中的移动性管理功能网元MME；
所述处理单元，具体用于若所述终端设备支持所述第一通信系统和第二通信系统，且所述终端的第三签约信息指示所述会话对应的数据网络标识APN支持和5G系统互通，则选择合设的会话管理功能网元作为所述目标会话管理网元。
在一种可能的实现方式中，第一通信系统为4G系统，第二通信系统为5G系统，所述网元选择的装置为所述4G系统中的移动性管理功能网元MME：
所述处理单元，具体用于若所述终端设备支持所述第一通信系统和第二通信系统，且所述第三签约信息指示所述会话的数据网络标识APN不支持和5G系统互通，则不选择合设的会话管理功能网元作为所述目标会话管理网元。具体的，所述不选择合设的会话管理功能网元作为所述目标会话管理网元，包括：所述选择所述4G系统中的会话管理功能网元作为所述目标会话管理网元。
在一种可能的实现方式中，所述装置还包括：
发送单元，用于向所述目标会话管理功能网元发送第二消息，以使得所述目标会话管理功能网元根据所述第二消息确定策略控制网元和计费系统。
第五方面，本申请实施例提供一种网元选择装置，该装置可以是第一通信系统中的第一网元，也可以第一通信系统中的第一网元内的芯片。该装置可以包括处理单元和收发单元。当该装置是第一通信系统中的第一网元时，该处理单元可以是处理器，该收发单元可以是收发器；该第一通信系统中的第一网元还可以包括存储单元，该存储单元可以是存储器；该存储单元用于存储指令，该处理单元执行该存储单元所存储的指令，以使该第一通信系统中的第一网元执行第一方面或第一方面任意一种可能的设计中的方法。当该装置是第一通信系统中的第一网元内的芯片时，该处理单元可以是处理器，该收发 单元可以是输入/输出接口、管脚或电路等；该处理单元执行存储单元所存储的指令，该存储单元用于存储指令，该存储单元可以是该芯片内的存储单元(例如，寄存器、缓存等)，也可以是该第一通信系统中的第一网元内的位于该芯片外部的存储单元(例如，只读存储器、随机存取存储器等)，以使该第一通信系统中的第一网元执行第一方面或第一方面任意一种可能的设计中的方法
第六方面，本申请实施例还提供一种计算机可读存储介质，该计算机可读存储介质存储有计算机程序，当该计算机程序在计算机上运行时，使得计算机执行上述第一方面或第二方面所述的方法。
第六方面，本申请实施例还提供一种包含程序的计算机程序产品，当其在计算机上运行时，使得计算机执行上述第一方面或第二方面所述的方法。
附图说明
图1为本申请实施例中4G系统与5G系统的互通架构的示意图；
图2为本申请实施例中网元选择方法的概述流程图；
图3为本申请实施例中UE在4G网络中建立会话连接的具体流程示意图之一；
图4为本申请实施例中UE在4G网络中建立会话连接的具体流程示意图之二；
图5为本申请实施例中UE在5G网络中建立会话连接的具体流程示意图之一；
图6为本申请实施例中UE在5G网络中建立会话连接的具体流程示意图之二；
图7为本申请实施例中网元选择装置的结构示意图；
图8为本申请实施例第一通信系统中的第一网元的结构示意图；
图9为本申请实施例中UE在4G网络中建立会话连接的具体流程示意图之三；
图10为本申请实施例中UE在5G网络中建立会话连接的具体流程示意图之三。
具体实施方式
下面结合附图，对本申请的实施例进行描述。
参阅图1所示为本申请实施例的具体应用场景示意图，应理解的是，图1仅为举例，不作为本申请的限定。
在如图1所示的4G系统与5G系统的互通架构中，4G网络与5G网络共用用户面功能(User Plane Function，UPF)+分组数据网络网关用户面功能(Packet Data Network Gateway User Plane Function，PGW-U)、会话管理功能(Session Management Function，SMF)+协议数据单元网关控制面功能(Protocol Data Unit Gateway Control plane function，PGW-C)、策略控制功能(Policy Control Function，PCF)+(Policy and Charging Rules Function，PCRF)策略与计费规则功能、归属签约用户服务器(Home Subscriber Server，HSS)+统一数据管理(Unified Data Management，UDM)。这里“+”表示合设，这里的“合设”是指同一个设备同时具备两个实体的功能。其中，UPF是5G的用户面功能网元，PGW-U是与UPF对应的4G的PDU网关用户面功能网元，UPF+PGW-U为合设的用户面功能网元，具备5G系统的用户面功能以及具备4G系统的用户面功能；SMF是5G的会话管理功能网元，PGW-C是与SMF对应的4G中的PDU网关控制面功能网元，SMF+PGW-C为合设的会话管理功能网元，具备5G系统的会话管理能力以及具备4G系统的会话管理能力；PCF是5G的策略与计费规则功能网元、PCRF为4G中的策略控制功能 网元，在线计费系统(online charging system，OCS)和离线计费系统(offline charging system，OFCS)为4G的计费系统网元，PCF+PCRF为合设的策略与计费规则功能网元，具备5G系统的策略与计费规则功能以及具备4G系统的策略与计费规则功能；UDM用于管理5G的用户数据，例如5G的用户数据包括用户在5G的签约信息，HSS与UDM对应，用于管理4G的用户数据，例如，4G的用户数据包括用户在4G的签约信息，HSS+UDM为合设的用户数据管理网元。需要说明的是，图1中下一代无线接入网(Next Generation Radio Access Networks，NG-RAN)是5G的接入网设备，演进的UMTS陆地无线接入网(Evolved UMTS Terrestrial Radio Access Network，E-UTRAN)是4G的接入网设备。在上述互通架构中，MME和E-UTRAN通过服务网关(Serving Gateway，SGW)与UPF+PGW-U或者SMF+PGW-C进行通信。此外，上述互通架构中还可以包括单纯的4G网元，例如，可以包括PGW-U、PGW-C、PCRF、HSS中至少一种，同理，上述互通架构中还可以包括单纯的5G网元，例如，可以包括UPF、SMF、PCF、UDM中至少一种。
应理解的是，当UE在5G系统接入时，如果接入和移动性管理功能(Core Access and Mobility Management Function，AMF)确定UE能够支持4G系统和5G系统，则AMF为该UE选择合设的会话管理功能网元建立连接。在某些场景下，UE并不需要使用4G网络的服务或没有签约4G网络的服务，即支持4G系统和5G系统的UE可能并没有互通的诉求。因此，此时AMF并不需要为该UE选择合设的会话管理功能网元。因此，当UE在5G系统接入时同样存在网元选择不合理的问题。因此，为了解决网元选择不合理的问题，本申请实施例提供一种网元选择方法，参阅图2所示，用以实现支持4G系统和5G系统且没有互通需求的UE合理选择网元，该方法包括：
步骤200：第一通信系统中的第一网元接收终端设备发送的第一消息，其中，第一消息用于请求建立会话。其中，第一消息用于请求建立会话，在一种可能的设计中，第一网元根据第一消息的消息类型或消息名称来确定该消息用于请求建立会话，比如第一消息为PDU会话建立请求(PDU Session Establishment Request),或者，第一消息为PDU连接请求(PDN Connectivity Request)，第一网元可以根据消息名称确定该消息用于请求建立会话，或者第一消息为附着请求(Attach Request)，第一网元可以根据消息类型确定UE在网络侧注册成功后需请求建立一个会话。
步骤210：第一通信系统中的第一网元响应于第一消息，根据第一签约信息和第二签约信息确定目标会话管理功能网元，第一签约信息包括终端设备在第一通信系统的签约信息，第二签约信息包括终端设备在第二通信系统中的签约信息。在一种可能的设计中，第一签约信息可以是终端设备在第一通信系统的一个或多个数据网络标识所对应的签约信息。第二签约信息也可以是终端设备在第二通信系统的一个或多个数据网络标识所对应的签约信息。在另一种可能的设计中，第一签约信息可以是一个指示信息，指示终端设备在第一通信系统中是否签约了某个数据网络标识，第二签约信息也可以是一个指示信息，指示终端设备在第二通信系统中是否签约了某个数据网络标识。
第一通信系统中的第一网元需要获取第一签约信息和第二签约信息。在一种可能的设计中，在步骤200之前，第一通信系统中的第一网元向合设的用户数据管理网元发送第三消息，其中，第三消息用于获取第一签约信息和第二签约信息。第一通信系统中的第一网元保存第一签约信息和第二签约信息。或者，第一通信系统中的第一网元分别向第一通信系统中的用户数据管理网元查询第一签约信息，向第二通信系统中的用户数据 管理网元查询第二签约信息。因此，第一通信系统中的第一网元可以提前保存第一签约信息和第二签约信息。在另一种可能的设计中，在步骤200之后，在步骤210之前，第一通信系统中的第一网元向合设的用户数据管理网元发送第四消息，其中，第四消息用于查询第一签约信息和第二签约信息。或者，第一通信系统中的第一网元分别向第一通信系统中的用户数据管理网元查询第一签约信息，向第二通信系统中的用户数据管理网元查询第二签约信息。因此，第一通信系统中的第一网元可以实时查询第一签约信息和第二签约信息。应理解的是，合设的用户数据管理网元可以为如图1所示的HSS+UDM。此外，第一通信系统中的第一网元在获取第一签约信息和第二签约信息之前，还可以确定当前会话的数据网络标识，然后获取终端设备在第一通信系统中该数据网络标识对应的签约信息作为第一签约信息，获取终端设备在第二通信系统中与该数据网络标识对应的数据网络标识所对应签约信息作为第二签约信息。
应理解的是，本申请对第一通信系统中的第一网元获取第一签约信息和第二签约信息的顺序不做限定，即第一网元可以同时获取第一签约信息和第二签约信息，也可以先获取第一签约信息，然后再获取第二签约信息。在一种可能的设计中，第一通信系统中的第一网元先获取第一签约信息，若确定存在第一签约信息，再获取第二签约信息，若确定不存在第一签约信息，则拒绝当前的会话建立请求，可选地，不再获取第二签约信息。
针对步骤210的一种可能实现方式，第一通信系统中的第一网元可以根据终端设备能力、第一签约信息和第二签约信息确定目标会话管理功能网元。可选的，在步骤200之前，第一通信系统中的第一网元接收终端设备发送的非接入层(Non Access Stratum，NAS)消息，该NAS消息中携带终端设备能力信息。或者，第一消息携带终端设备能力信息。例如，终端设备能力信息包括终端设备是否支持第一通信系统的信息和终端设备是否支持第二通信系统的信息，或者，终端设备能力信息包括终端设备是否第一通信系统和第二通信系统的指示信息。因此，第一通信系统中的第一网元根据终端设备能力信息可以确定终端设备是否支持第一通信系统和第二通信系统。
下面结合具体应用场景说明第一通信系统中的第一网元根据终端设备能力、第一签约信息和第二签约信息确定目标会话管理功能网元的具体过程。
场景1：第一通信系统为4G系统，所述第二通信系统为5G系统，第一通信系统中的第一网元为MME。
场景1可以具体包括两种可能的情况：
第一种可能的情况：若终端设备支持第一通信系统和第二通信系统，且第一签约信息和第二签约信息均包括会话的数据网络标识对应的签约信息，则MME选择合设的会话管理功能网元作为目标会话管理网元，例如如图1中所示的SMF+PGW-C。
第二种可能的情况：若终端设备支持第一通信系统和第二通信系统，且第一签约信息包括会话的数据网络标识对应的签约信息，且第二签约信息不包括会话的数据网络标识对应的签约信息，则MME选择4G系统中的会话管理功能网元作为目标会话管理网元，例如如图1中所示的PGW-C。
在上述两种可能的情况中，MME均需要通过两个判断步骤确定目标会话管理网元，本申请对于两个判断步骤的执行顺序不做限定：
其中一个判断步骤为终端设备是否支持第一通信系统和第二通信系统，具体的，MME 可以根据终端设备能力信息确定终端设备支持第一通信系统和第二通信系统；
另一个判断步骤为第一签约信息和第二签约信息是否均包括会话的数据网络标识对应的签约信息。
首先，MME需要确定会话的数据网络标识。当第一通信系统为4G系统，第二通信系统为5G系统时，会话的数据网络标识为接入点名称(Access Point Name，APN)。本申请对确定APN的具体方式不作限定。在一种可能的设计中，第一消息中携带会话的数据网络标识，MME可以根据第一消息确定会话的数据网络标识。在另一种可能的设计中，第一消息中未携带数据网络标识，MME可以确定一个APN，例如，一个默认的APN，或者根据本地策略或本地配置等为该会话确定一个配置的APN。下文中MME确定会话的数据网络标识的方法与此处一致，重复之处不再赘述。
在第一种实现方式中，MME根据确定的APN确定或获取第一签约信息和第二签约信息，此时第一签约信息为终端设备在4G系统该APN的签约信息，也可以是一个指示信息，指示终端设备是否签约了该APN。第二签约信息为终端设备在5G系统中与APN对应的数据网络名称(Data Network Name，DNN)的签约信息，也可以是一个指示信息，指示终端设备是否签约了该DNN，其中，APN与DNN对应，或者，第二签约信息为终端设备在5G系统中与APN对应的DNN+单网络切片选择辅助信息(Single Network Slice Selection Assistance information，S-NSSAI)的签约信息，也可以是一个指示信息，指示终端设备是否签约了该DNN+S-NSSAI，其中，APN与DNN+S-NSSAI对应。具体地，针对第一种可能，MME判断第一签约信息和第二签约信息均包括会话的数据网络标识对应的签约信息的方式为：终端设备在4G系统中有该APN签约信息，且终端设备在5G系统中有与该APN对应的DNN签约信息；或者，终端设备在4G系统中有该APN签约信息，且终端设备在5G系统中有与该APN对应的DNN+S-NSSAI签约信息。针对第二种可能，MME判断第一签约信息包括会话的数据网络标识对应的签约信息，且第二签约信息不包括会话的数据网络标识对应的签约信息的方式为：终端设备在4G系统中有该APN签约信息，且终端设备在5G系统中没有与该APN对应的DNN签约信息；或者，终端设备在4G系统中有该APN签约信息，且终端设备在5G系统中没有与该APN对应的DNN+S-NSSAI签约信息。值得注意的是，本申请中DNN+S-NSSAI签约信息是指DNN加上S-NSSAI粒度的签约信息，下文中提到的DNN+S-NSSAI签约信息与此处含义相同，重复之处不再赘述。
在第二种可能的实现方式中，MME首先获取终端设备在4G系统的所有签约信息和5G系统的所有签约信息。此时，第一签约信息包括终端设备在4G系统签约的各个APN分别对应的签约信息，第二签约信息包括终端设备在5G系统签约的各个DNN分别对应的签约信息，或者第二签约信息包括终端设备在5G系统签约的各个DNN+S-NSSAI分别对应的签约信息。具体地，针对第一种可能，MME判断第一签约信息和第二签约信息均包括会话的数据网络标识对应的签约信息的方式为：MME判断第一签约信息中包含了该APN对应的签约信息，且第二签约信息中包含了与该APN对应的DNN签约信息；或者，第一签约信息中包含了该APN对应的签约信息，且第二签约信息中包含了与该APN对应的DNN+S-NSSAI签约信息。针对第二种可能，MME判断第一签约信息包括会话的数据网络标识对应的签约信息，且第二签约信息不包括会话的数据网络标识对应的签约信息的方式为：MME判断第一签约信息中包含了该APN对应的签约信息，且第二签约信息中没有包含与该APN对应的DNN签约信息；或者，MME判断第一签约信息中包含了该APN对应的签约信息，且第二签约信息中没有包含与该APN对应的DNN+S-NSSAI签约信息。
在第三种可能的实现方式中，MME首先获取终端设备在4G系统的所有签约信息，第一签约信息包括终端设备在4G系统签约的各个APN分别对应的签约信息，然后MME根据确定的APN确定或获取第二签约信息，第二签约信息为终端设备在5G系统中与该APN对应的DNN签约信息，也可以是一个指示信息，指示终端设备是否签约了该DNN，或者，第二签约信息为终端设备在5G系统中与该APN对应的DNN+S-NSSAI签约信息，也可以是一个指示信息，指示终端设备是否签约了该DNN+S-NSSAI。具体地，针对第一种可能，MME判断第一签约信息和第二签约信息均包括会话的数据网络标识对应的签约信息的方式为：第一签约信息中包含了该APN对应的签约信息，且终端设备在5G系统中有与该APN对应的DNN签约信息；或者，第一签约信息中包含了该APN对应的签约信息，且终端设备在5G系统中有与该APN对应的DNN+S-NSSAI签约信息。针对第二种可能，MME判断第一签约信息包括会话的数据网络标识对应的签约信息，且第二签约信息不包括会话的数据网络标识对应的签约信息的方式为：第一签约信息中包含了该APN对应的签约信息，且终端设备在5G系统中没有与该APN对应的DNN签约信息；或者，第一签约信息中包含了该APN对应的签约信息，且终端设备在5G系统中没有与该APN对应的DNN+S-NSSAI签约信息。
应理解的是，并非第一签约信息中包括的各个APN分别对应的签约信息都在第二签约信息中存在与之一一对应的DNN的签约信息，只有一部分APN的签约信息在5G系统中存在与之一一对应的DNN签约信息。同理，并非第一签约信息中包括的各个APN分别对应的签约信息都在第二签约信息中存在与之一一对应的DNN+S-NSSAI的签约信息，只有一部分APN的签约信息在5G系统中存在与之一一对应的DNN+S-NSSAI签约信息。
在第四种可能的实现方式中，若终端设备支持第一通信系统和第二通信系统，在MME确定APN后，MME向合设的用户数据管理网元发送第五消息，第五消息用于查询该APN对应的签约信息是否存在与该APN对应的DNN对应的签约信息。MME接收合设的用户数据管理网元发送的查询结果，若该查询结果指示该APN对应的签约信息存在与该APN对应的DNN对应的签约信息，则MME选择合设的会话管理功能网元，若该查询结果指示该APN对应的签约信息不存在与该APN对应的DNN对应的签约信息，则MME选择4G系统中的会话管理功能网元。或者，若终端设备支持第一通信系统和第二通信系统，在MME确定APN后，MME向合设的用户数据管理网元发送第五消息，第五消息用于查询该APN对应的签约信息是否存在与该APN对应的DNN+S-NSSAI对应的签约信息。MME接收合设的用户数据管理网元发送的查询结果，若该查询结果指示该APN对应的签约信息存在与该APN对应的DNN+S-NSSAI对应的签约信息，则MME选择合设的会话管理功能网元，若该查询结果指示该APN对应的签约信息不存在与该APN对应的DNN+S-NSSAI对应的签约信息，则MME选择4G系统中的会话管理功能网元。
在第五种可能的实现方式中，MME向合设的用户数据管理网元发送第六消息，第六消息用于获取APN与DNN的映射关系，该映射关系指示APN签约信息存在对应的DNN签约信息，MME接收合设的用户数据管理网元发送的映射关系，并保存该映射关系，例如，MME可以在接收终端设备发送的第一消息前向合设的用户数据管理网元发送第六消息，或者，MME可以在接收终端设备发送的第一消息后向合设的用户数据管理网元发送第六消息。MME在确定APN后，根据该APN查询该映射关系，若该映射关系指示该APN存在对应的DNN，则MME选择合设的会话管理功能网元，若该映射关系指示该APN不存在对应的DNN，则MME选择4G系统中的会话管理功能网元。同理，上述设计也适用于APN与 DNN和S-NSSAI对应的情况，此处不再赘述。
例如，终端设备在4G系统签约3个APN，包括APN1、APN2和APN3，并在5G系统签约4个DNN，包括DNN1、DNN2、DNN3和DNN4，其中，APN1与DNN2对应，APN3与DNN3对应，则该映射关系包括APN1与DNN2，以及APN3与DNN3。若MME确定APN2，则根据APN2查询该映射关系确定APN2不存在对应的DNN，则MME选择4G系统中的会话管理功能网元，若MME确定APN3，则根据APN3查询该映射关系确定APN4存在对应的DNN为DNN3，则MME选择合设的会话管理功能网元。
因此，通过上述各种可能的实现方式，MME可以为有互通能力且有互通需求的终端设备选择合设的会话管理功能网元为目标会话管理功能网元。MME可以为有互通能力但没有互通需求(即不需要使用5G网络的服务或没有签约5G网络的服务)的终端设备选择4G系统中的会话管理功能网元作为目标会话管理网元，就能够满足会话需求，且可以减轻合设的会话管理功能网元的负载。
场景2：第一通信系统为5G系统，第二通信系统为4G系统，第一通信系统中的第一网元为AMF。
场景2可以具体包括两种可能的情况：
第一种可能的情况：若终端设备支持第一通信系统和第二通信系统，且第一签约信息和第二签约信息均包括会话的数据网络标识对应的签约信息，则AMF选择合设的会话管理功能网元作为目标会话管理网元，例如如图1中所示的SMF+PGW-C。
第二种可能的情况：若终端设备支持第一通信系统和第二通信系统，且第一签约信息包括会话的数据网络标识对应的签约信息，第二签约信息不包括会话的数据网络标识对应的签约信息，则AMF选择5G系统中的会话管理功能网元作为目标会话管理网元，其中，5G通信系统中的会话管理功能网元为SMF。
与场景1类似，在上述两种可能的情况中，AMF均需要通过两个判断步骤确定目标会话管理网元，对于两个判断步骤的执行顺序不做限定：
一个判断步骤为终端设备是否支持第一通信系统和第二通信系统，具体的，AMF可以根据终端设备能力信息确定终端设备支持第一通信系统和第二通信系统；
另外一个判断步骤为AMF判断第一签约信息和第二签约信息是否均包括会话的数据网络标识对应的签约信息。
首先，AMF确定当前会话的数据网络标识。当第一通信系统为5G系统，第二通信系统为4G系统时，会话的数据网络标识为DNN，或者DNN和S-NSSAI。本申请对确定DNN的具体方式或者DNN和S-NSSAI的具体方式不作限定。在一种可能的设计中，第一消息中携带会话的数据网络标识，AMF可以根据第一消息确定会话的数据网络标识。在另一种可能的设计中，第一消息中未携带数据网络标识，AMF可以确定一个DNN或DNN和S-NSSAI，例如，一个默认的DNN或DNN和S-NSSAI，或者根据本地策略或本地配置等为该会话确定一个配置的DNN或DNN和S-NSSAI。下文中AMF确定会话的数据网络标识的方法与此处一致，重复之处不再赘述。
在第一种实现方式中，AMF根据确定的DNN确定或获取第一签约信息和第二签约信息，此时第一签约信息为终端设备在5G系统该DNN的签约信息，也可以是一个指示信息，指示终端设备是否签约了该DNN。第二签约信息为终端设备在4G系统中与该DNN对应的APN签约信息，其中，APN与DNN对应，或者，第二签约信息为终端设备在4G系统中与 该DNN和S-NSSAI对应的APN的签约信息，其中，APN与DNN+S-NSSAI对应，也可以是一个指示信息，指示终端设备是否签约了该APN。具体地，针对第一种可能，AMF判断第一签约信息和第二签约信息均包括会话的数据网络标识对应的签约信息的方式为：终端设备在5G系统中有该DNN签约信息，且终端设备在4G系统中有与该DNN对应的APN签约信息；或者，终端设备在5G系统中有该DNN+S-NSSAI签约信息，且终端设备在4G系统中有与该DNN+S-NSSAI对应的APN签约信息。针对第二种可能，AMF判断第一签约信息包括会话的数据网络标识对应的签约信息，且第二签约信息不包括会话的数据网络标识对应的签约信息的方式为：终端设备在5G系统中有该DNN签约信息，且终端设备在4G系统中没有与该DNN对应的APN签约信息；或者，终端设备在5G系统中有该DNN+S-NSSAI签约信息，且终端设备在4G系统中没有与该DNN+S-NSSAI对应的APN签约信息。
在第二种可能的实现方式中，AMF首先获取终端设备在4G系统的所有签约信息和5G系统的所有签约信息。此时，第一签约信息包括终端设备在5G系统签约的各个DNN分别对应的签约信息，或者第一签约信息包括终端设备在5G系统签约的各个DNN+S-NSSAI分别对应的签约信息。第二签约信息包括终端设备在4G系统签约的各个APN的签约信息。具体地，针对第一种可能，AMF判断第一签约信息和第二签约信息均包括会话的数据网络标识对应的签约信息的方式为：AMF判断第一签约信息中包含了该DNN对应的签约信息，且第二签约信息中包含了与该DNN对应的APN签约信息。或者，AMF判断第一签约信息中包含了该DNN+S-NSSAI对应的签约信息，且第二签约信息中包含了与该DNN+S-NSSAI对应的APN签约信息。针对第二种可能，AMF判断第一签约信息包括会话的数据网络标识对应的签约信息，且第二签约信息不包括会话的数据网络标识对应的签约信息的方式为：AMF判断第一签约信息中包含了该DNN对应的签约信息，且第二签约信息中没有包含与该DNN对应的APN签约信息。或者，AMF判断第一签约信息中包含了该DNN+S-NSSAI对应的签约信息，且第二签约信息中没有包含与该DNN+S-NSSAI对应的APN签约信息。
在第三种可能的实现方式中，AMF首先获取终端设备在5G系统的所有签约信息，第一签约信息包括终端设备在5G系统签约的各个DNN的签约信息，或者第一签约信息包括终端设备在5G系统签约的各个DNN+S-NSSAI分别对应的签约信息。AMF根据确定的DNN或者DNN+S-NSSA确定或获取第二签约信息，第二签约信息为终端设备在4G系统中与该DNN或者该DNN+S-NSSA对应的APN签约信息，也可以是一个指示信息，指示终端设备是否签约了该APN。具体地，针对第一种可能，AMF判断第一签约信息和第二签约信息均包括会话的数据网络标识对应的签约信息的方式为：第一签约信息中包含了该DNN对应的签约信息，且终端设备在4G系统中有与该DNN对应的APN签约信息；或者，第一签约信息中包含了该DNN+S-NSSAI对应的签约信息，且终端设备在4G系统中有与该DNN+S-NSSAI对应的APN签约信息。针对第二种可能，AMF判断第一签约信息包括会话的数据网络标识对应的签约信息，且第二签约信息不包括会话的数据网络标识对应的签约信息的方式为：第一签约信息中包含了该DNN对应的签约信息，且终端设备在4G系统中没有与该DNN对应的APN签约信息；或者，第一签约信息中包含了该DNN+S-NSSAI对应的签约信息，且终端设备在4G系统中没有与该DNN+S-NSSAI对应的APN签约信息。
应理解的是，并非第一签约信息中包括的各个DNN分别对应的签约信息都在第二签约信息中存在与之一一对应的APN的签约信息，只有一部分DNN的签约信息在4G系统中 存在与之一一对应的APN签约信息。同理，并非第一签约信息中包括的各个DNN+S-NSSAI分别对应的签约信息都在第二签约信息中存在与之一一对应的APN的签约信息，只有一部分DNN+S-NSSAI的签约信息在4G系统中存在与之一一对应的APN签约信息。
在第四种可能的实现方式中，若终端设备支持第一通信系统和第二通信系统，AMF确定DNN后，AMF向合设的用户数据管理网元发送第七消息，第七消息用于查询该DNN对应的签约信息是否存在与该DNN对应的APN对应的签约信息。AMF接收合设的用户数据管理网元发送的查询结果，若该查询结果指示确定存在与该DNN对应的APN对应的签约信息，则AMF选择合设的会话管理功能网元，若该查询结果指示该DNN对应的签约信息不存在与该DNN对应的APN对应的签约信息，则AMF选择5G系统中的会话管理功能网元。或者，若终端设备支持第一通信系统和第二通信系统，在AMF确定DNN+S-NSSAI后，AMF向合设的用户数据管理网元发送第七消息，第七消息用于查询该DNN+S-NSSAI对应的签约信息是否存在与该DNN+S-NSSAI对应的APN签约信息。AMF接收合设的用户数据管理网元发送的查询结果，若该查询结果指示确定存在与该DNN+S-NSSAI对应的APN对应的签约信息，则AMF选择合设的会话管理功能网元，若该查询结果指示该DNN+S-NSSAI对应的签约信息不存在与该DNN+S-NSSAI对应的APN对应的签约信息，则AMF选择5G系统中的会话管理功能网元。
在第五种可能的实现方式中，若终端设备支持第一通信系统和第二通信系统，AMF向合设的用户数据管理网元发送第八消息，第八消息用于获取DNN与APN的映射关系，AMF接收合设的用户数据管理网元发送的映射关系，并保存该映射关系，例如，AMF可以在接收终端设备发送的第一消息前向合设的用户数据管理网元发送第八消息，或者，AMF可以在接收终端设备发送的第一消息后向合设的用户数据管理网元发送第八消息。AMF在确定DNN后，根据该DNN查询该映射关系，若该映射关系指示该DNN存在对应的APN，则AMF选择合设的会话管理功能网元，若该映射关系指示该DNN不存在对应的APN，则AMF选择5G系统中的会话管理功能网元。同理，上述设计也适用于DNN+S-NSSAI与APN对应的情况，此处不再赘述。
例如，终端设备在4G系统签约3个APN，包括APN1、APN2和APN3，并在5G系统签约4个DNN，包括DNN1、DNN2、DNN3和DNN4，其中，APN1与DNN2对应，APN3与DNN3对应，则该映射关系包括APN1与DNN2，以及APN3与DNN3。若AMF确定DNN2，则根据DNN2查询该映射关系确定DNN2存在对应的APN为APN1，则AMF选择合设的会话管理功能网元，若AMF确定DNN1，则根据DNN1查询该映射关系确定DNN1不存在对应的APN，则AMF选择5G系统中的会话管理功能网元。
因此，通过上述各种可能的实现方式，AMF可以为有互通能力且有互通需求的终端设备选择合设的会话管理功能网元为目标会话管理功能网元。AMF可以为有互通能力但没有互通需求(即不需要使用4G网络的服务或没有签约4G网络的服务)的终端设备选择5G系统中的会话管理功能网元作为目标会话管理网元，就能够满足会话需求，且可以减轻合设的会话管理功能网元的负载。
此外，第一通信系统中的第一网元还可以根据终端设备能力、第一签约信息和第二签约信息确定第二消息，向目标会话管理功能网元发送第二消息，以使得目标会话管理功能网元根据第二消息确定策略控制网元和计费系统。其中，第二消息中包括指示信息指示目标会话管理功能网元选择合设的策略控制网元和计费系统或者第一通信系统中的 策略控制网元和计费系统。
下面分别针对场景1和场景2进行具体说明。
场景1：第一通信系统为4G系统，所述第二通信系统为5G系统，第一通信系统中的第一网元为MME。
若终端设备支持第一通信系统和第二通信系统，且第一签约信息包括会话的数据网络标识对应的签约信息，且第二签约信息不包括会话的数据网络标识对应的签约信息，MME选择了合设的会话管理功能网元，MME向合设的会话管理功能网元发送第二消息，以使得合设的会话管理功能网元根据第二消息确定策略控制网元和计费系统为4G系统的策略控制网元和计费系统。其中，第二消息中包括指示信息指示合设的会话管理功能网元选择4G系统中的策略控制网元和计费系统。因此，MME可以通过第二消息指示合设的会话管理功能网元为有互通能力但没有互通需求(即不需要使用5G网络的服务或没有签约5G网络的服务)的终端设备选择4G系统中的策略控制网元和计费系统，可以减轻合设的策略控制网元和计费系统的负载。
例如，在一种可能的组网中，PGW-C全部升级成了SMF+PGW-C，但策略控制网元和计费系统网元没有升级，即4G的策略控制网元可以为PCRF，计费系统网元可以为OCS和OFCS，在这种情况下，MME虽然选择到了SMF+PGW-C，但SMF+PGW-C并不感知当前UE没有互通需求，即不会接入到5G系统中。因此，MME可向SMF+PGW-C发送第二消息，第二消息包括指示信息指示SMF+PGW-C选择并且接入到4G的策略控制网元和计费系统。
应理解的是，一般地，当MME选择4G的会话管理功能网元，4G的会话管理功能网元会选择4G的策略控制网元和计费系统，当MME选择合设的会话管理功能网元，合设的会话管理功能网元会选择合设的策略控制网元和计费系统。而采用本申请实施例提供的方法，MME可以指示合设的会话管理功能网元选择4G系统中的策略控制网元和计费系统，进而可以实现减轻合设的策略控制网元和计费系统的负载。
场景2：第一通信系统为5G系统，第二通信系统为4G系统，第一通信系统中的第一网元为AMF。
若终端设备支持第一通信系统和第二通信系统，且第一签约信息包括会话的数据网络标识对应的签约信息，且第二签约信息不包括会话的数据网络标识对应的签约信息，AMF选择了合设的会话管理功能网元，AMF向合设的会话管理功能网元发送第二消息，以使得合设的会话管理功能网元根据第二消息确定策略控制网元和计费系统为5G的策略控制网元和计费系统。其中，第二消息中包括指示信息指示合设的会话管理功能网元选择5G系统中的策略控制网元和计费系统。因此，AMF可以通过第二消息指示合设的会话管理功能网元为有互通能力但没有互通需求(即不需要使用4G网络的服务或没有签约4G网络的服务)的终端设备选择5G系统中的策略控制网元和计费系统，可以减轻合设的策略控制网元和计费系统的负载。
例如，在一种可能的组网中，单纯的SMF设备还未开始部署，即SMF+PGW-C全部都是在PGW-C上做的升级，但策略控制网元和计费系统的相关网元没有升级，因此，AMF只能选择SMF+PGW-C，AMF向SMF+PGW-C发送第二消息，第二消息包括指示信息指示SMF+PGW-C选择并接入到5G的策略控制网元和计费系统，比如，PCF。
应理解的是，一般地，当AMF选择5G的会话管理功能网元，5G的会话管理功能网元会选择5G的策略控制网元和计费系统，当AMF选择合设的会话管理功能网元，合设的会话管理功能网元会选择合设的策略控制网元和计费系统。而采用本申请实施例提供的 方法，AMF可以指示合设的会话管理功能网元选择5G系统中的策略控制网元和计费系统，进而可以实现减轻合设的策略控制网元和计费系统的负载。
下面结合附图对具体说明本申请实施例的网元选择过程。
参阅图3所示为UE在4G网络中建立会话连接的具体过程之一。
步骤301：MME获取UE能力信息。在一种可能的设计中，在附着(Attach)流程中或跟踪区更新(Track area update，TAU)流程中，UE发送NAS消息给MME，该NAS消息中携带UE能力信息(UE capabilities)，其中UE capabilities包括UE是否支持4G系统、UE是否支持5G系统等信息，或者UE capabilities包括UE是否同时支持4G系统和5G系统的指示信息。MME保存UE capabilities。
步骤302：UE向MME发送请求会话消息，该请求会话消息也可以包括在附着请求(Attach request)中。该会话请求消息可以为NAS消息。
步骤303：MME确定APN。在一种可能的设计中，请求会话消息中携带APN。在另一种可能的设计中，请求会话消息中未携带APN，MME可以确定一个APN，例如，默认的APN。
步骤304：MME根据UE能力信息、第一签约信息和第二签约信息确定目标会话管理功能网元。若终端设备支持4G系统和5G系统，且第一签约信息和第二签约信息均包括APN对应的签约信息，MME执行步骤305a；若终端设备支持4G系统和5G系统，且第一签约信息包括APN对应的签约信息，且第二签约信息不包括APN对应的签约信息，MME执行步骤305b。应理解的是，MME根据UE能力信息、第一签约信息和第二签约信息确定目标会话管理功能网元的具体过程可以参照上述场景1中的可能的实现方式，重复之处不再赘述。
在一种可能的设计中，在步骤302之前，例如，在Attach流程或TAU流程中，MME向HSS+UDM发送第三消息，其中，第三消息用于获取第一签约信息和第二签约信息。MME保存第一签约信息和第二签约信息。在另一种可能的设计中，在步骤303之后，MME向HSS+UDM发送第四消息，其中，第四消息用于查询第一签约信息和第二签约信息。
步骤305a：MME选择SMF+PGW-C作为目标会话管理网元，向SMF+PGW-C发送请求会话消息。
步骤305b：MME选择PGW-C作为目标会话管理网元，向PGW-C发送请求会话消息。后续会话建立流程，主要包括无线资源的配置、用户面隧道的建立等，具体可参照现有技术。
参阅图4所示为UE在4G网络中建立会话连接的具体过程之二。其中，PGW-C全部升级成了SMF+PGW-C，但策略控制网元和计费系统的相关网元没有升级，4G的策略控制网元为PCRF，4G的计费系统网元为OCS和OFCS，5G的策略控制网元和计费系统为PCF。
步骤401-步骤403与步骤301-步骤303相同。
步骤404：MME根据UE能力信息、第一签约信息和第二签约信息是否确定目标策略控制网元和计费系统。若终端设备支持4G系统和5G系统，且第一签约信息和第二签约信息均包括APN对应的签约信息，MME执行步骤405a；若终端设备支持4G系统和5G系统，且第一签约信息包括APN对应的签约信息，且第二签约信息不包括APN对应的签约信息，MME执行步骤405b。
步骤405a：MME向SMF+PGW-C发送请求会话消息。该请求会话消息可以不携带指示信息，或者携带第一指示信息，该第一指示信息指示SMF+PGW-C选择合设的策略控制网 元和计费系统。因此，目标策略控制网元和计费系统为合设的策略控制网元和计费系统。
步骤405b：MME向SMF+PGW-C发送请求会话消息，该请求会话请求消息携带第二指示信息，该第二指示信息指示SMF+PGW-C选择4G的策略控制网元和计费系统。因此，目标策略控制网元和计费系统为4G的策略控制网元和计费系统。
参阅图5所示为UE在5G网络中建立会话连接的具体过程之一。以下仅以DNN与APN对应为例进行说明，DNN+S-NSSAI与APN对应的处理流程类似，此处不再赘述。
步骤501：AMF获取UE能力信息。在一种可能的设计中，在注册(Registration)流程或重新注册(Re-registration)流程中，UE发送NAS消息给AMF，该NAS消息中携带UE能力信息(UE capabilities)，其中UE capabilities包括UE是否支持4G系统、UE是否支持5G系统等信息，或者UE capabilities包括UE是否同时支持4G系统和5G系统的指示信息。AMF保存UE capabilities。
步骤502：UE向AMF发送请求会话消息，该会话请求消息为NAS消息。
步骤503：AMF确定DNN。在一种可能的设计中，请求会话消息中携带DNN。在另一种可能的设计中，请求会话消息中未携带DNN，AMF可以确定一个APN，例如，默认的DNN。
步骤504：AMF根据UE能力信息、第一签约信息和第二签约信息确定目标会话管理功能网元。若终端设备支持4G系统和5G系统，且第一签约信息和第二签约信息均包括DNN对应的签约信息，AMF执行步骤505a；若终端设备支持4G系统和5G系统，且第一签约信息包括DNN对应的签约信息，且第二签约信息不包括DNN对应的签约信息，AMF执行步骤505b。应理解的是，AMF根据UE能力信息、第一签约信息和第二签约信息确定目标会话管理功能网元的具体过程可以参照上述场景2中的可能的实现方式，重复之处不再赘述。
在一种可能的设计中，在步骤502之前，例如，在Registration流程或Re-registration流程中，AMF向HSS+UDM发送第三消息，其中，第三消息用于获取第一签约信息和第二签约信息。AMF保存第一签约信息和第二签约信息。在另一种可能的设计中，在步骤503之后，AMF向HSS+UDM发送第四消息，其中，第四消息用于查询第一签约信息和第二签约信息。
步骤505a：AMF选择SMF+PGW-C作为目标会话管理网元，向SMF+PGW-C发送请求会话消息。
步骤505b：AMF选择SMF作为目标会话管理网元，向SMF发送请求会话消息。
后续会话建立流程，主要包括无线资源的配置、用户面隧道的建立等，具体可参照现有技术。
参阅图6所示为UE在5G网络中建立会话连接的具体过程之二。其中，单纯的SMF设备还未开始部署，即SMF+PGW-C全部都是在PGW-C上做的升级，但策略控制网元和计费系统的相关网元没有升级，比如4G的策略控制网元为PCRF，4G的计费系统为OCS和OFCS。在5G也有独立的策略控制网元和计费系统，比如PCF。
步骤601-步骤603与步骤501-步骤503相同。
步骤604：AMF根据UE能力信息、第一签约信息和第二签约信息是否确定目标策略控制网元和计费系统，若终端设备支持4G系统和5G系统，且第一签约信息和第二签约信息均包括DNN对应的签约信息，AMF执行步骤605a；若终端设备支持4G系统和5G系统，且第一签约信息包括DNN对应的签约信息，且第二签约信息不包括DNN对应的签约信息，AMF执行步骤605b。
步骤605a：AMF向SMF+PGW-C发送请求会话消息。该请求会话消息可以不携带指示信息，或者携带第一指示信息，该第一指示信息指示SMF+PGW-C选择合设的策略控制网元和计费系统。因此，目标策略控制网元和计费系统为合设的策略控制网元和计费系统。
步骤605b：AMF向SMF+PGW-C发送请求会话消息，该会话请求消息携带第二指示信息，该第二指示信息指示SMF+PGW-C选择并接入到5G的策略控制网元和计费系统。因此，目标策略控制网元和计费系统为4G的策略控制网元和计费系统。
基于以上实施例，本申请实施例提供一种网元选择装置，如图7所示，该装置700包括：
接收单元701，用于接收终端设备发送的第一消息，所述第一消息用于请求建立会话；
处理单元702，用于响应于所述第一消息，根据第一签约信息和第二签约信息确定目标会话管理功能网元，所述第一签约信息包括所述终端设备在所述第一通信系统的签约信息，所述第二签约信息包括所述终端设备在第二通信系统中的签约信息。
在一种可能的设计中，所述处理单元702，具体用于：根据所述终端设备能力、所述第一签约信息和所述第二签约信息确定所述目标会话管理功能网元。
在一种可能的设计中，所述第一通信系统为4G系统，所述第二通信系统为5G系统，所述装置为MME；所述处理单元702，具体用于：若所述终端设备支持所述第一通信系统和第二通信系统，且所述第一签约信息和所述第二签约信息均包括所述会话的数据网络标识对应的签约信息，则选择合设的会话管理功能网元作为所述目标会话管理网元，其中，具备5G系统的会话管理能力以及具备4G系统的会话管理能力的网元为合设的会话管理功能网元。
在一种可能的设计中，所述第一通信系统为4G系统，所述第二通信系统为5G系统，所述装置为MME；所述处理单元702，具体用于：若所述终端设备支持所述第一通信系统和第二通信系统，且所述第一签约信息包括所述会话的数据网络标识对应的签约信息，且所述第二签约信息不包括所述会话的数据网络标识对应的签约信息，则选择所述4G系统中的会话管理功能网元作为所述目标会话管理网元。
在一种可能的设计中，所述第一通信系统为5G系统，所述第二通信系统为4G系统，所述装置为AMF；所述处理单元702，具体用于：若所述终端设备支持所述第一通信系统和第二通信系统，且所述第一签约信息和所述第二签约信息均包括所述会话的数据网络标识对应的签约信息，则选择合设的会话管理功能网元作为所述目标会话管理网元，其中，具备5G系统的会话管理能力以及具备4G系统的会话管理能力的网元为合设的会话管理功能网元。
在一种可能的设计中，所述第一通信系统为5G系统，所述第二通信系统为4G系统，所述装置为AMF；所述处理单元702，具体用于：若所述终端设备支持所述第一通信系统和第二通信系统，且所述第一签约信息包括所述会话的数据网络标识对应的签约信息，所述第二签约信息不包括所述会话的数据网络标识对应的签约信息，则择所述5G系统中的会话管理功能网元作为所述目标会话管理网元。
在一种可能的设计中，还包括：发送单元703，用于向所述目标会话管理功能网元发送第二消息，以使得所述目标会话管理功能网元根据所述第二消息确定策略控制网元和计费系统。
可以理解的，关于图7的网元选择装置包括的功能模块的具体实现方式及相应的有益效果，可参考前述图2所示实施例的具体介绍，这里不赘述。
应理解以上各个单元的划分仅仅是一种逻辑功能的划分，实际实现时可以全部或部分集成到一个物理实体上，也可以物理上分开。且这些单元可以全部以软件通过处理元件调用的形式实现；也可以全部以硬件的形式实现，还可以部分单元以软件通过处理元件调用的形式实现，部分单元以硬件的形式实现。在实现过程中，上述方法的各步骤或以上各个单元可以通过处理器元件中的硬件的集成逻辑电路或者软件形式的指令完成。
例如，以上这些单元可以是被配置成实施以上方法的一个或多个集成电路，例如：一个或多个特定集成电路(Application Specific Integrated Circuit，ASIC)，或，一个或多个微处理器(digital signal processor，DSP)，或，一个或者多个现场可编程门阵列(Field Programmable Gate Array，FPGA)等。再如，当以上某个单元通过处理元件调度程序的形式实现时，该处理元件可以是通用处理器，例如中央处理器(Central Processing Unit，CPU)或其它可以调用程序的处理器。再如，这些单元可以集成在一起，以片上系统(system-on-a-chip，SOC)的形式实现。
作为另一种可选的变形，本申请实施例提供一种网元选择装置，示例性地，可以为一种芯片，该装置包括处理器和接口，该接口可以为输入/输出接口。其中，处理器完成上述处理单元702的功能，接口完成上述接收单元701和发送单元702的功能。该装置还可以包括存储器，存储器用于存储可在处理器上运行的程序，处理器执行该程序时实现上述如图2所示实施例的方法。
基于以上实施例，本申请实施例还提供了一种第一通信系统中的第一网元，参阅图8所示，该网元800中包括：收发器801、处理器802、存储器803。其中，存储器803用于存储计算机程序；处理器802调用存储器803存储的计算机程序，通过收发器801执行上述如图2所示的方法。其中，处理器可以是CPU，网络处理器(network processor，NP)，硬件芯片或者其任意组合。存储器可以包括易失性存储器(volatile memory)，例如随机存取存储器(random access memory，RAM)，也可以包括非易失性存储器(non-volatile memory)，例如只读存储器(read-only memory，ROM)，快闪存储器(flash memory)，硬盘(hard disk drive，HDD)或固态硬盘(solid-state drive，SSD)，存储器还可以包括上述种类的存储器的组合。
可以理解的，上述图7所示实施例中的装置可以以图8所示的网元800实现。具体的，处理单元702可以由处理器802实现，接收单元701和发送单元703可以由收发器801实现。网元800的结构并不构成对本申请实施例的限定。
参阅图9所示为UE在4G网络中建立会话连接的具体过程之一。
步骤901：MME获取UE能力信息。在一种可能的设计中，在附着(Attach)流程中或跟踪区更新(Track area update，TAU)流程中，UE发送NAS消息给MME，该NAS消息中携带UE能力信息(UE capabilities)，其中UE capabilities包括UE是否支持4G系统、UE是否支持5G系统等信息，或者UE capabilities包括UE是否同时支持4G系统和5G系统的指示信息。MME保存UE capabilities。
步骤902：UE向MME发送请求会话消息，该请求会话消息也可以包括在附着请求(Attach request)中。该会话请求消息可以为NAS消息。
步骤903：MME确定APN。在一种可能的设计中，步骤902中的请求会话消息携带APN。 在另一种可能的设计中，请求会话消息中未携带APN，MME可以确定一个APN，例如，默认的APN。确定APN的方式如前所述，不再赘述。
步骤904：MME根据UE能力信息(或称为终端能力)、第三签约信息确定目标会话管理功能网元。具体的，若终端能力指示UE支持4G系统和5G系统，所述终端的第三签约指示所述会话对应的数据网络标识APN支持和5G系统(或称为5GC)互通，则所述MME选择合设的会话管理功能网元作为所述目标会话管理网元，执行步骤905a。可选的，所述终端的第三签约指示所述会话对应的数据网络标识APN支持和5G系统(或称为5GC)互通还包括：终端的第三签约信息是一个指示信息，指示所述会话对应的数据网络标识APN支持和某个DNN以及某个网络切片标识S-NSSAI互通。其中，合设的会话管理功能网元可以为同时具备4G系统的会话管理能力以及5G系统的会话管理能力的网元，比如SMF+PGW-C。若所述终端能力指示UE支持4G系统和5G系统，且所述第三签约信息指示所述会话的数据网络标识APN不支持和5G系统互通，则所述MME不选择合设的会话管理功能网元作为所述目标会话管理网元，执行步骤905b。所述MME不选择合设的会话管理功能网元作为所述目标会话管理网元，包括：所述MME选择一个不是用于专门做互通的会话管理功能网元作为所述目标会话管理网元,比如一个单纯的4G系统中的PGW-C或PGW。因此，MME可以为有互通能力且有互通需求的终端设备选择合设的会话管理功能网元为目标会话管理功能网元。
此外，MME还可以根据终端设备能力、第三签约信息确定第二消息，向目标会话管理功能网元发送第二消息，以使得目标会话管理功能网元根据第二消息确定策略控制网元和计费系统。其中，第二消息中包括指示信息指示目标会话管理功能网元选择合设的策略控制网元和计费系统或者第一通信系统中的策略控制网元和计费系统。具体过程，可参考前图4所对应的实施例。
步骤905a：MME选择SMF+PGW-C作为目标会话管理网元，向SMF+PGW-C发送请求会话消息。
步骤905b：MME选择PGW-C作为目标会话管理网元，向PGW-C发送请求会话消息。
后续会话建立流程，主要包括无线资源的配置、用户面隧道的建立等，具体可参照现有技术。
因此，MME可以为有互通能力但没有互通需求(即不支持与5G互通)的终端设备选择4G系统中的会话管理功能网元作为目标会话管理网元，就能够满足会话需求，进而可以减轻合设的会话管理功能网元的负载。可选地，MME可以指示合设的会话管理网元为有互通能力但没有互通需求(即不支持与5G互通)的终端设备选择4G系统中的策略控制网元和计费系统，进而可以减轻合设的策略控制网元和计费系统的负载。
进一步，可以理解的是，图9所对应的实施例中所涉及的描述，如有不清楚的地方，可参考前述实施例的解释。
另外，图9中MME的逻辑结构可如图7所示，可通过图7中的处理单元、接收单元以及发送单元实现图9所描述的步骤。可以理解的，上述图7所示实施例中的装置可以以图8所示的网元800实现。具体的，处理单元702可以由处理器802实现，接收单元701和发送单元703可以由收发器801实现。网元800的结构并不构成对本申请实施例的限定。
参阅图10所示为UE在5G网络中建立会话连接的具体过程之一。
步骤1001：AMF获取UE能力信息。在一种可能的设计中，在注册(Registration)流程或重新注册(Re-registration)流程中，UE发送NAS消息给AMF，该NAS消息中携带UE能力信息(UE capabilities)，其中UE capabilities包括UE是否支持4G系统、UE是否支持5G系统等信息，或者UE capabilities包括UE是否同时支持4G系统和5G系统的指示信息。AMF保存UE capabilities。
步骤1002：UE向AMF发送请求会话消息，该会话请求消息为NAS消息。
步骤1003：AMF确定DNN。在一种可能的设计中，步骤1002中的请求会话消息携带DNN。在另一种可能的设计中，请求会话消息中未携带DNN，AMF可以确定一个APN，例如，默认的DNN。确定DNN的方式如前所述，不再赘述。
步骤1004：AMF根据UE能力信息(或称为终端能力)、第三签约信息确定目标会话管理功能网元。具体的，若终端能力指示UE支持4G系统和5G系统，所述终端的第三签约指示所述会话对应的数据网络标识DNN支持和4G系统(或称为EPS，或EPC)互通，则所述AMF选择合设的会话管理功能网元作为所述目标会话管理网元，执行步骤1005a。可选的，所述终端的第三签约指示所述会话对应的数据网络标识DNN支持和4G系统(或称为EPS，或EPC)互通还包括：终端的第三签约信息是一个指示信息，指示所述会话对应的数据网络标识DNN和网络切片标识S-NSSAI支持互通。其中，合设的会话管理功能网元可以为同时具备4G系统的会话管理能力以及5G系统的会话管理能力的网元，比如SMF+PGW-C。若所述终端能力指示UE支持4G系统和5G系统，且所述第三签约信息指示所述会话的数据网络标识DNN不支持和4G系统互通，则所述AMF不选择合设的会话管理功能网元作为所述目标会话管理网元，执行步骤1005b。所述AMF不选择合设的会话管理功能网元作为所述目标会话管理网元，包括：所述AMF选择一个不是用于专门做互通的会话管理功能网元作为所述目标会话管理网元,比如一个单纯的5G系统中的SMF。因此，AMF可以为有互通能力且有互通需求的终端设备选择合设的会话管理功能网元为目标会话管理功能网元。
此外，AMF还可以根据终端设备能力、第三签约信息确定第二消息，向目标会话管理功能网元发送第二消息，以使得目标会话管理功能网元根据第二消息确定策略控制网元和计费系统。其中，第二消息中包括指示信息指示目标会话管理功能网元选择合设的策略控制网元和计费系统或者第一通信系统中的策略控制网元和计费系统。具体过程，可参考前图6所对应的实施例。
步骤1005a：AMF选择SMF+PGW-C作为目标会话管理网元，向SMF+PGW-C发送请求会话消息。
步骤1005b：AMF选择SMF作为目标会话管理网元，向SMF发送请求会话消息。
后续会话建立流程，主要包括无线资源的配置、用户面隧道的建立等，具体可参照现有技术。
因此，AMF可以为有互通能力但没有互通需求(即不支持与4G互通)的终端设备选择5G系统中的会话管理功能网元作为目标会话管理网元，就能够满足会话需求，进而可以减轻合设的会话管理功能网元的负载。可选地，AMF可以指示合设的会话管理网元为有互通能力但没有互通需求(即不支持与4G互通)的终端设备选择5G系统中的策略控制网元和计费系统，进而可以减轻合设的策略控制网元和计费系统的负载。
进一步，可以理解的是，图10所对应的实施例中所涉及的描述，如有不清楚的地方，可参考前述实施例的解释。
另外，图10中AMF的逻辑结构可如图7所示，可通过图7中的处理单元、接收单元以及发送单元实现图10所描述的步骤。可以理解的，上述图7所示实施例中的装置可以以图8所示的网元800实现。具体的，处理单元702可以由处理器802实现，接收单元701和发送单元703可以由收发器801实现。网元800的结构并不构成对本申请实施例的限定。
本申请实施例还提供一种计算机可读存储介质，该计算机可读存储介质存储有计算机程序，当该计算机程序在计算机上运行时，使得计算机执行上述如图2所示实施例的方法，可以使得处理器执行如图9所示的MME所对应的步骤；还可以使得处理器执行如图10所示的AMF所对应的步骤。
综上所述，采用本申请实施例提供的方法，第一通信系统中的第一网元接收终端设备发送的第一消息，该第一消息用于请求建立会话，响应于所述第一消息，第一通信系统中的第一网元根据第一签约信息和第二签约信息确定目标会话管理功能网元，相较于现有技术中仅根据终端设备是否支持4G系统和5G系统选择网元，可以实现支持4G系统和5G系统且没有互通需求的终端设备合理地选择网元，且可以减轻合设的会话管理功能网元的负载。
当第一通信系统为4G系统，所述第二通信系统为5G系统，第一通信系统中的第一网元为MME时，MME可以为有互通能力且有互通需求的终端设备选择合设的会话管理功能网元为目标会话管理功能网元。MME可以为有互通能力但没有互通需求(即不需要使用5G网络的服务或没有签约5G网络的服务)的终端设备选择4G系统中的会话管理功能网元作为目标会话管理网元，就能够满足会话需求，且可以减轻合设的会话管理功能网元的负载。
当第一通信系统为5G系统，第二通信系统为4G系统，第一通信系统中的第一网元为AMF时，AMF可以为有互通能力且有互通需求的终端设备选择合设的会话管理功能网元为目标会话管理功能网元。AMF可以为有互通能力但没有互通需求(即不需要使用4G网络的服务或没有签约4G网络的服务)的终端设备选择5G系统中的会话管理功能网元作为目标会话管理网元，就能够满足会话需求，且可以减轻合设的会话管理功能网元的负载。
当第一通信系统为4G系统，第二通信系统为5G系统，第一通信系统中的第一网元为MME时，MME可以通过第二消息指示合设的会话管理功能网元为有互通能力但没有互通需求(即不需要使用5G网络的服务或没有签约5G网络的服务)的终端设备选择4G系统中的策略控制网元和计费系统，可以减轻合设的策略控制网元和计费系统的负载。当第一通信系统为5G系统，第二通信系统为4G系统，第一通信系统中的第一网元为AMF时，AMF可以通过第二消息指示合设的会话管理功能网元为有互通能力但没有互通需求(即不需要使用4G网络的服务或没有签约4G网络的服务)的终端设备选择5G系统中的策略控制网元和计费系统，可以减轻合设的策略控制网元和计费系统的负载。
本领域内的技术人员应明白，本申请实施例可提供为方法、系统、或计算机程序产品。因此，本申请实施例可采用完全硬件实施例、完全软件实施例、或结合软件和硬件方面的实施例的形式。而且，本申请实施例可采用在一个或多个其中包含有计算机可用 程序代码的计算机可用存储介质(包括但不限于磁盘存储器、CD-ROM、光学存储器等)上实施的计算机程序产品的形式。
本申请实施例是参照根据本申请实施例的方法、设备(系统)、和计算机程序产品的流程图和/或方框图来描述的。应理解可由计算机程序指令实现流程图和/或方框图中的每一流程和/或方框、以及流程图和/或方框图中的流程和/或方框的结合。可提供这些计算机程序指令到通用计算机、专用计算机、嵌入式处理机或其他可编程数据处理设备的处理器以产生一个机器，使得通过计算机或其他可编程数据处理设备的处理器执行的指令产生用于实现在流程图一个流程或多个流程和/或方框图一个方框或多个方框中指定的功能的装置。
这些计算机程序指令也可存储在能引导计算机或其他可编程数据处理设备以特定方式工作的计算机可读存储器中，使得存储在该计算机可读存储器中的指令产生包括指令装置的制造品，该指令装置实现在流程图一个流程或多个流程和/或方框图一个方框或多个方框中指定的功能。
这些计算机程序指令也可装载到计算机或其他可编程数据处理设备上，使得在计算机或其他可编程设备上执行一系列操作步骤以产生计算机实现的处理，从而在计算机或其他可编程设备上执行的指令提供用于实现在流程图一个流程或多个流程和/或方框图一个方框或多个方框中指定的功能的步骤。
显然，本领域的技术人员可以对本申请实施例进行各种改动和变型而不脱离本申请的精神和范围。这样，倘若本申请实施例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 (38)

  1. 一种网元选择方法，其特征在于，该方法包括：
    第一通信系统中的第一网元接收终端设备发送的第一消息，所述第一消息用于请求建立会话；
    响应于所述第一消息，所述第一通信系统中的第一网元根据第一签约信息和第二签约信息确定目标会话管理功能网元，所述第一签约信息包括所述终端设备在所述第一通信系统的签约信息，所述第二签约信息包括所述终端设备在第二通信系统中的签约信息。
  2. 根据权利要求1所述的方法，其特征在于，所述第一通信系统中的第一网元根据第一签约信息和第二签约信息确定目标会话管理功能网元，包括：
    所述第一通信系统中的第一网元根据所述终端设备能力、所述第一签约信息和所述第二签约信息确定所述目标会话管理功能网元。
  3. 如权利要求2所述的方法，其特征在于，所述第一通信系统为4G系统，所述第二通信系统为5G系统，所述第一通信系统中的第一网元为移动性管理实体MME；
    所述第一通信系统中的第一网元根据所述终端设备能力、所述第一签约信息和所述第二签约信息确定所述目标会话管理功能网元，包括：
    若所述终端设备支持所述第一通信系统和第二通信系统，且所述第一签约信息和所述第二签约信息均包括所述会话的数据网络标识对应的签约信息，则所述MME选择合设的会话管理功能网元作为所述目标会话管理网元，其中，具备5G系统的会话管理能力以及具备4G系统的会话管理能力的网元为合设的会话管理功能网元。
  4. 如权利要求2所述的方法，其特征在于，所述第一通信系统为4G系统，所述第二通信系统为5G系统，所述第一通信系统中的第一网元为MME；
    所述第一通信系统中的第一网元根据所述终端设备能力、所述第一签约信息和所述第二签约信息确定所述目标会话管理功能网元，包括：
    若所述终端设备支持所述第一通信系统和第二通信系统，且所述第一签约信息包括所述会话的数据网络标识对应的签约信息，且所述第二签约信息不包括所述会话的数据网络标识对应的签约信息，则所述MME选择所述4G系统中的会话管理功能网元作为所述目标会话管理网元。
  5. 如权利要求2所述的方法，其特征在于，所述第一通信系统为5G系统，所述第二通信系统为4G系统，所述第一通信系统中的第一网元为接入和移动性管理功能AMF；
    所述第一通信系统中的第一网元根据所述终端设备能力、所述第一签约信息和所述第二签约信息确定所述目标会话管理功能网元，包括：
    若所述终端设备支持所述第一通信系统和第二通信系统，且所述第一签约信息和所述第二签约信息均包括所述会话的数据网络标识对应的签约信息，则所述AMF选择合设的会话管理功能网元作为所述目标会话管理网元，其中，具备5G系统的会话管理能力以及具备4G系统的会话管理能力的网元为合设的会话管理功能网元。
  6. 如权利要求2所述的方法，其特征在于，所述第一通信系统为5G系统，所述第二通信系统为4G系统，所述第一通信系统中的第一网元为AMF；
    所述第一通信系统中的第一网元根据所述终端设备能力、所述第一签约信息和所述第二签约信息确定所述目标会话管理功能网元，包括：
    若所述终端设备支持所述第一通信系统和第二通信系统，且所述第一签约信息包括 所述会话的数据网络标识对应的签约信息，所述第二签约信息不包括所述会话的数据网络标识对应的签约信息，则所述AMF选择所述5G系统中的会话管理功能网元作为所述目标会话管理网元。
  7. 如权利要求1至6任一所述的方法，其特征在于，还包括：
    所述第一通信系统中的第一网元向所述目标会话管理功能网元发送第二消息，以使得所述目标会话管理功能网元根据所述第二消息确定策略控制网元和计费系统。
  8. 一种网元选择方法，其特征在于，该方法包括：
    第一通信系统中的第一网元接收终端设备发送的第一消息，所述第一消息用于请求建立会话；
    响应于所述第一消息，所述第一通信系统中的第一网元根据所述终端设备能力和所述终端的第三签约信息确定目标会话管理功能网元。
  9. 如权利要求8所述的方法，其特征在于，所述第一通信系统中的第一网元为接入和移动性管理功能网元AMF，所述第一通信系统中的第一网元根据所述终端设备能力和所述终端的第三签约信息确定目标会话管理功能网元，包括：
    若所述终端设备支持所述第一通信系统和第二通信系统，且所述终端的第三签约信息指示所述会话对应的数据网络标识DNN支持和4G系统互通，则所述AMF选择合设的会话管理功能网元作为所述目标会话管理网元；其中，所述第一通信系统为5G系统，所述第二通信系统为4G系统。
  10. 如权利要求8所述的方法，其特征在于，所述第一通信系统中的第一网元为接入和移动性管理功能网元AMF，所述第一通信系统中的第一网元根据所述终端设备能力和所述终端的第三签约信息确定目标会话管理功能网元，包括：
    若所述终端设备支持所述第一通信系统和第二通信系统，且所述第三签约信息指示所述会话的数据网络标识DNN不支持和4G系统互通，则所述AMF不选择合设的会话管理功能网元作为所述目标会话管理网元；其中，所述第一通信系统为5G系统，所述第二通信系统为4G系统。
  11. 如权利要求10所述的方法，其特征在于，所述AMF不选择合设的会话管理功能网元作为所述目标会话管理网元，包括：所述AMF选择所述5G系统中的会话管理功能网元作为所述目标会话管理网元。
  12. 如权利要求8所述的方法，其特征在于，所述第一通信系统中的第一网元为移动性管理功能网元MME，所述第一通信系统中的第一网元根据所述终端设备能力和所述终端的第三签约信息确定目标会话管理功能网元，包括：
    若所述终端设备支持所述第一通信系统和第二通信系统，且所述终端的第三签约信息指示所述会话对应的数据网络标识APN支持和5G系统互通，则所述MME选择合设的会话管理功能网元作为所述目标会话管理网元；其中，所述第一通信系统为4G系统，所述第二通信系统为5G系统。
  13. 如权利要求8所述的方法，其特征在于，所述第一通信系统中的第一网元为移动性管理功能网元MME，所述第一通信系统中的第一网元根据所述终端设备能力和所述终端的第三签约信息确定目标会话管理功能网元，包括：
    若所述终端设备支持所述第一通信系统和第二通信系统，且所述第三签约信息指示 所述会话的数据网络标识APN不支持和5G系统互通，则所述MME不选择合设的会话管理功能网元作为所述目标会话管理网元；其中，所述第一通信系统为4G系统，所述第二通信系统为5G系统。
  14. 如权利要求13所述的方法，其特征在于，所述MME不选择合设的会话管理功能网元作为所述目标会话管理网元，包括：所述MME选择所述4G系统中的会话管理功能网元作为所述目标会话管理网元。
  15. 如权利要求8至14任一所述的方法，其特征在于，还包括：
    所述第一通信系统中的第一网元向所述目标会话管理功能网元发送第二消息，以使得所述目标会话管理功能网元根据所述第二消息确定策略控制网元和计费系统。
  16. 一种网元选择装置，其特征在于，该装置包括：
    接收单元，用于接收终端设备发送的第一消息，所述第一消息用于请求建立会话；
    处理单元，用于响应于所述第一消息，根据第一签约信息和第二签约信息确定目标会话管理功能网元，所述第一签约信息包括所述终端设备在所述第一通信系统的签约信息，所述第二签约信息包括所述终端设备在第二通信系统中的签约信息。
  17. 根据权利要求16所述的装置，其特征在于，所述处理单元，具体用于：
    根据所述终端设备能力、所述第一签约信息和所述第二签约信息确定所述目标会话管理功能网元。
  18. 如权利要求17所述的装置，其特征在于，所述第一通信系统为4G系统，所述第二通信系统为5G系统，所述装置为MME；
    所述处理单元，具体用于：
    若所述终端设备支持所述第一通信系统和第二通信系统，且所述第一签约信息和所述第二签约信息均包括所述会话的数据网络标识对应的签约信息，则选择合设的会话管理功能网元作为所述目标会话管理网元，其中，具备5G系统的会话管理能力以及具备4G系统的会话管理能力的网元为合设的会话管理功能网元。
  19. 如权利要求17所述的装置，其特征在于，所述第一通信系统为4G系统，所述第二通信系统为5G系统，所述装置为MME；
    所述处理单元，具体用于：
    若所述终端设备支持所述第一通信系统和第二通信系统，且所述第一签约信息包括所述会话的数据网络标识对应的签约信息，且所述第二签约信息不包括所述会话的数据网络标识对应的签约信息，则选择所述4G系统中的会话管理功能网元作为所述目标会话管理网元。
  20. 如权利要求17所述的装置，其特征在于，所述第一通信系统为5G系统，所述第二通信系统为4G系统，所述装置为AMF；
    所述处理单元，具体用于：
    若所述终端设备支持所述第一通信系统和第二通信系统，且所述第一签约信息和所述第二签约信息均包括所述会话的数据网络标识对应的签约信息，则选择合设的会话管理功能网元作为所述目标会话管理网元，其中，具备5G系统的会话管理能力以及具备4G系统的会话管理能力的网元为合设的会话管理功能网元。
  21. 如权利要求17所述的装置，其特征在于，所述第一通信系统为5G系统，所述第二通信系统为4G系统，所述装置为AMF；
    所述处理单元，具体用于：
    若所述终端设备支持所述第一通信系统和第二通信系统，且所述第一签约信息包括所述会话的数据网络标识对应的签约信息，所述第二签约信息不包括所述会话的数据网络标识对应的签约信息，则择所述5G系统中的会话管理功能网元作为所述目标会话管理网元。
  22. 如权利要求16至21任一所述的装置，其特征在于，还包括：
    发送单元，用于向所述目标会话管理功能网元发送第二消息，以使得所述目标会话管理功能网元根据所述第二消息确定策略控制网元和计费系统。
  23. 一种网元选择的装置，其特征在于，该装置包括：
    接收单元，用于接收终端设备发送的第一消息，所述第一消息用于请求建立会话；
    处理单元，用于响应于所述第一消息，根据所述终端设备能力和所述终端的第三签约信息确定目标会话管理功能网元。
  24. 如权利要求23所述的装置，其特征在于，所述处理单元，具体用于若所述终端设备支持所述第一通信系统和第二通信系统，且所述终端的第三签约信息指示所述会话对应的数据网络标识DNN支持和4G系统互通，则选择合设的会话管理功能网元作为所述目标会话管理网元；第一通信系统为5G系统，第二通信系统为4G系统，所述网元选择装置为5G系统中的接入和移动性管理功能网元AMF。
  25. 如权利要求23所述的装置，其特征在于，所述处理单元，具体用于若所述终端设备支持所述第一通信系统和第二通信系统，且所述第三签约信息指示所述会话的数据网络标识DNN不支持和4G系统互通，则不选择合设的会话管理功能网元作为所述目标会话管理网元；其中，第一通信系统为5G系统，第二通信系统为4G系统，所述网元选择装置为5G系统中的接入和移动性管理功能网元AMF。
  26. 如权利要求25所述的装置，其特征在于，所述不选择合设的会话管理功能网元作为所述目标会话管理网元，包括：选择所述5G系统中的会话管理功能网元作为所述目标会话管理网元。
  27. 如权利要求23所述的装置，其特征在于，所述处理单元，具体用于若所述终端设备支持所述第一通信系统和第二通信系统，且所述终端的第三签约信息指示所述会话对应的数据网络标识APN支持和5G系统互通，则选择合设的会话管理功能网元作为所述目标会话管理网元；其中，第一通信系统为4G系统，第二通信系统为5G系统，所述网元选择的装置为4G系统中的移动性管理功能网元MME。
  28. 如权利要求23所述的装置，其特征在于，
    所述处理单元，具体用于若所述终端设备支持所述第一通信系统和第二通信系统，且所述第三签约信息指示所述会话的数据网络标识APN不支持和5G系统互通，则不选择合设的会话管理功能网元作为所述目标会话管理网元；其中，第一通信系统为4G系统，第二通信系统为5G系统，所述网元选择的装置为所述4G系统中的移动性管理功能网元MME。
  29. 如权利要求28所述的装置，其特征在于，所述不选择合设的会话管理功能网元作为所述目标会话管理网元，包括：所述选择所述4G系统中的会话管理功能网元作为所 述目标会话管理网元。
  30. 如权利要求23至29任一所述的装置，其特征在于，所述装置还包括：
    发送单元，用于向所述目标会话管理功能网元发送第二消息，以使得所述目标会话管理功能网元根据所述第二消息确定策略控制网元和计费系统。
  31. 一种计算机存储介质，其特征在于，所述计算机存储介质中存储有计算机软件指令，当所述计算机指令被执行时，所述权利要求1至7任一所述的方法会被运行。
  32. 一种计算机存储介质，其特征在于，所述计算机存储介质中存储有计算机软件指令，当所述计算机指令被执行时，所述权利要求8至15任一所述的方法会被运行。
  33. 一种计算机程序产品，其特征在于，所述计算机程序产品包含指令，当所述指令所执行时，所述权利要求1至7任一所述的方法会被运行。
  34. 一种计算机程序产品，其特征在于，所述计算机程序产品包含指令，当所述指令所执行时，所述权利要求8至15任一所述的方法会被运行。
  35. 一种获取密钥的装置，其特征在于，所述装置包括处理器和收发器；所述处理器被配置为支持所述装置执行权利要求1至7任一所述的方法中相应的功能；所述收发器用于支持该所述装置与其他网络设备之间的通信。
  36. 一种获取密钥的装置，其特征在于，所述装置包括处理器和收发器；所述处理器被配置为支持所述装置执行权利要求8至15任一所述的方法中相应的功能；所述收发器用于支持该所述装置与其他网络设备之间的通信。
  37. 一种获取密钥的装置，其特征在于，所述装置用于执行权利要求1至7任一所述的方法。
  38. 一种获取密钥的装置，其特征在于，所述装置用于执行权利要求8至15任一所述的方法。
PCT/CN2019/082963 2018-05-08 2019-04-17 一种网元选择方法及装置 WO2019214407A1 (zh)

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