WO2019033369A1 - 一种通信系统间移动方法及装置 - Google Patents

一种通信系统间移动方法及装置 Download PDF

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Publication number
WO2019033369A1
WO2019033369A1 PCT/CN2017/097937 CN2017097937W WO2019033369A1 WO 2019033369 A1 WO2019033369 A1 WO 2019033369A1 CN 2017097937 W CN2017097937 W CN 2017097937W WO 2019033369 A1 WO2019033369 A1 WO 2019033369A1
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WIPO (PCT)
Prior art keywords
communication system
core network
network device
information
pdn connection
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PCT/CN2017/097937
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English (en)
French (fr)
Inventor
金辉
欧阳国威
窦凤辉
杨皓睿
李小娟
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.)
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Publication date
Application filed by 华为技术有限公司 filed Critical 华为技术有限公司
Priority to CN201780082017.8A priority Critical patent/CN110140385B/zh
Priority to CN202011150362.0A priority patent/CN112399512B/zh
Priority to CN202210228337.2A priority patent/CN114710813B/zh
Priority to PCT/CN2017/097937 priority patent/WO2019033369A1/zh
Publication of WO2019033369A1 publication Critical patent/WO2019033369A1/zh

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/0005—Control or signalling for completing the hand-off
    • H04W36/0011—Control or signalling for completing the hand-off for data sessions of end-to-end connection
    • H04W36/0033—Control or signalling for completing the hand-off for data sessions of end-to-end connection with transfer of context information
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/0005—Control or signalling for completing the hand-off
    • H04W36/0055—Transmission or use of information for re-establishing the radio link
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/14—Reselecting a network or an air interface
    • 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

Definitions

  • the present application relates to the field of communications technologies, and in particular, to a method and an apparatus for moving between communication systems.
  • the 5th Generation (5G) mobile communication technology is an extension of the fourth generation (Forth Generation, 4G) mobile communication technology, featuring high performance, low latency and high capacity, and the highest data transmission speed can reach dozens. Above Gbps, the data transmission speed is 1000 times faster than the existing 4th generation (4G) network.
  • the UE may establish a Protocol Data Network (PDN) connection in the 4G network.
  • PDN Protocol Data Network
  • MME mobility management entity
  • the Access and Mobility Management Function (AMF) sends the context information of the UE, where the context information includes PDN connection information established by the UE in the 4G network, where the PDN connection information includes the PDN.
  • PGW IP address of the gateway
  • the embodiment of the present invention provides a method and an apparatus for moving between communication systems for moving a UE from a first communication system to a second communication system, which solves the problem of long processing delay in the UE mobile process in the prior art.
  • a method for moving between communication systems comprising: establishing, by a user equipment UE, at least one PDN connection in a first communication system, for example, the first communication system is a 4G communication system; and the UE generates a first PDU session
  • the first PDU session state information is used to indicate a PDU session corresponding to the PDN connection that is supported in the at least one PDN connection to the second communication system.
  • the first PDU session state information is an identifier of the PDU session.
  • the UE sends a registration message to the core network device of the second communication system, where the registration message includes the first PDU session state information.
  • the second communication system is a 5G communication system, and the core network device is access and mobility in the 5G. Management function AMF); the UE receives a registration accept message sent by the core network device of the second communication system.
  • the UE generates first PDU session state information by using a PDN connection supported in the at least one PDN to move to the second communication system, and sends the first PDU session state information to the core network of the second communication system by using a registration message.
  • a device such that the core network device of the second communication system sends a registration acceptance to the UE a message, thereby moving the UE from the first communication system to the second communication system based on the PDU session corresponding to the PDN connection that supports moving to the second communication system, thereby preventing the UE from being unreachable during the mobile process because the PDN gateway is unreachable
  • the problem of prolonged processing during the move is a device, such that the core network device of the second communication system sends a registration acceptance to the UE a message, thereby moving the UE from the first communication system to the second communication system based on the PDU session corresponding to the PDN connection that supports moving to the second communication system, thereby preventing the UE from being unreachable during the mobile process because the
  • the UE establishes at least one PDN connection in the first communications system, including: the UE is to a core network device of the first communications system, for example, the core network device is 4G.
  • the mobility management entity (MME) in the network sends a first message, where the first message is used by the UE to establish a PDN connection in the first communication system.
  • the first message may be an attach request or a PDN connection request; the UE receives The first information, the first information is used by the UE to determine whether the PDN connection supports or does not support moving to the second communication system, and the first information may be included in an attach accept message or a PDN connection accept message.
  • the UE may acquire information that each PDN connection supports or does not support moving to the second communication system during the establishment of the PDN connection, so that the UE can be accurately connected from the at least one PDN based on the information.
  • a PDN connection that supports moving to the second communication system is determined.
  • the UE generates first PDU session state information, including: the UE generates a first PDU by using an identifier of a PDU session corresponding to a PDN connection that is supported to be moved to the second communications system. Session status information.
  • the UE may generate the first PDU session state information by using the identifier of the corresponding PDU session, so that the PDU session can be indicated by the identifier simply and effectively.
  • the UE generates the first PDU session state information by using an identifier of the PDU session corresponding to the PDN connection that is moved to the second communication system, including: the UE moves to the support according to the support.
  • the identity of the PDN connection of the second communication system obtains the identity of the PDU session.
  • the identifier of the PDN connection is processed according to a certain rule to obtain an identifier of the corresponding PDU session, and the identifier of the PDN connection is increased or decreased by a fixed value to obtain an identifier of the corresponding PDN session.
  • the UE obtains the identifier of the PDU session according to the identifier of the PDN connection that supports moving to the second communications system, including: the UE will support the PDN connection moving to the second communications system
  • the identifier of the PDU session is set as the identifier of the corresponding PDU session.
  • the first information includes first indication information, where the first indication information is used to indicate that the PDN connection of the UE supports moving to the second communications system
  • the method further includes: the UE Determining, according to the first indication information, that the PDN connection supports moving to the second communication system; or, the first information includes second indication information, where the second indication information is used to indicate that the PDN connection of the UE does not support moving to the second communication system, the method The method further includes: determining, by the UE according to the second indication information, that the PDN connection does not support moving to the second communication system.
  • the UE may determine that the PDN connection supports or does not support moving to the second communication system by using the first information and the different indication information.
  • the first information includes session information of a PDU session corresponding to the PDN connection, where the session information includes at least one of the following information: a session AMBR, a QoS rule, an SSC mode, or a PDU.
  • the session identifier the method further includes: the UE determining, according to the session information, that the PDN connection supports moving to the second communication system.
  • an indication method is provided, that is, the UE may determine that the UE supports the mobile to the second communication system by using the session information of the PDU session in the first information.
  • the first information is included in a protocol configuration option PCO, where the PCO is used for parameter information transmission between the UE and the PDN gateway, and the UE and the PDN gateway Other devices between the devices do not resolve the PCO.
  • the first information is included in the PCO, which can reduce signaling interaction in the network.
  • the method before the UE generates the first PDU session state information, the method further includes: determining, by the UE, that the UE needs to be moved from the first communications system to the second communications system, that is, the UE is in the UE. In the idle state, the UE may actively initiate a process of moving from the first communication system to the second communication system.
  • the registration accept message includes the second PDU session state information, where the second PDU session state information is used to indicate the PDU session used by the UE in the second communications system, that is, the first
  • the core network device in the second communication system determines the PDU session used by the UE in the second communication system from the PDU session indicated by the first PDU session state information; the method further includes: deleting, by the UE, the session state with the second PDU The PDN connection other than the PDN connection corresponding to the PDU session indicated by the information, that is, the UE may delete the context information of the PDN connection that is not transferred to the second communication system.
  • the consistency of the context information of the connection and the storage used on the UE can be ensured by deleting the context information of the PDN connection that is not transferred to the second communication system. At the same time, it can also save a certain amount of storage space.
  • the first communication system is a fourth generation 4G communication system
  • the second communication system is a fifth generation 5G communication system.
  • a method for moving between communication systems comprising: determining, by a core network device of a first communication system, that a user equipment UE needs to move to a second communication system; and a core network device of the first communication system to a second communication system
  • the core network device sends context information of the PDN connection supported by the UE to the second communication system, and the context information of the PDN connection is used by the core network device of the second communication system to establish a PDU session corresponding to the PDN connection, so that the When the UE moves from the first communication system to the second communication system, the core network device of the second communication system establishes a PDU session corresponding to the PDN connection in the second communication system according to the context information of the PDN connection.
  • the core network device of the first communication system after determining that the UE needs to move to the second communication system, sends the context information of the PDN connection supported by the UE to the second communication system to the core of the second communication system.
  • a network device such that the core network device of the second communication system establishes a PDU session corresponding to the PDN connection, so that the UE is based on the PDU session corresponding to the PDN connection supporting the second communication system from the first communication system to the second communication
  • the system moves, avoiding the problem of prolonged processing during the mobile process because the PDN gateway is unreachable during the mobile process.
  • the method before the core network device of the first communication system sends the context information of the PDN connection on the UE that supports moving to the second communication system to the core network device of the second communication system, the method also includes the core network device of the first communication system determining that the PDN connection supports or does not support moving to the second communication system.
  • the core network device of the first communications system may obtain information that each PDN connection supports or does not support moving to the second communications system during the establishment of the PDN connection, so as to determine, according to the information, that the UE supports moving to the first The PDN connection of the two communication systems.
  • the core network device of the first communications system determines that the user equipment UE needs to move to the second communications system, including: the core network device of the first communications system receives the sending by the base station Switching the request; the core network device of the first communication system determines that the UE needs to move to the second communication system according to the handover request.
  • the base station of the first communication system may send a handover request to the core network device of the first communication system, to switch the UE from the first communication system to the second communication system. .
  • the method further includes: deleting, by the core network device of the first communications system, a PDN connection that does not support moving to the second communications system on the UE.
  • the first communication system may delete the PDN connection that is not transferred to the second communication system, which may save certain transmission resources.
  • the core network device of the first communications system determines that the user equipment UE needs to move to the second communications system, including: the core network device of the first communications system receives the context request message; The core network device of a communication system belongs to the second communication system according to the sender of the context request message, and determines that the UE needs to move to the second communication system.
  • the core network device of the first communication system may determine that the UE needs to move to the second communication system by the sender of the context request message belonging to the second communication system.
  • the context request message includes the second information, where the second information is used to indicate that the sender of the context request message belongs to the second communication system; or the context request message includes the GUTI of the UE.
  • the method further includes: the core network device of the first communication system determines that the sender of the context request message belongs to the second communication system according to the GUTI of the UE being mapped from the GUTI of the second communication system.
  • the core network device of the first communication system can quickly and accurately determine that the sender belongs to the second communication system by using the information in the context request message.
  • the method further includes: determining, by the core network device of the first communications system, that the UE does not support moving to a PDN connection in the second communications system, the core of the first communications system.
  • the network device sends a session deletion request, and the session deletion request includes an operation indication flag.
  • the receiver of the session deletion request is deleted to delete the corresponding connection, thereby saving certain network resources.
  • the first communication system is a fourth generation 4G communication system
  • the second communication system is a fifth generation 5G communication system.
  • a method for inter-system mobility comprising: acquiring, by a first core network device of a second communication system, for example, an access and mobility management function (AMF in a 5G communication system)
  • the PDN in the communication system is connected to the address of the corresponding PDN gateway; the first core network device sends the first information to the second core network device (for example, the network storage function entity NRF) of the second communication system, where the first information includes the PDN gateway.
  • the second core network device for example, the network storage function entity NRF
  • the first core network device receives the second information sent by the second core network device, where the second information is used to indicate that the address of the PDN gateway is reachable or unreachable; when the address of the PDN gateway is reachable, the first core network The device sends the context information of the PDN connection to the PDN gateway, and the context information of the PDN connection is used by the PDN gateway to establish a PDU session corresponding to the PDN connection in the second communication system, so as to implement the UE moving from the first communication system to the second communication system. .
  • the first core network device after acquiring the address of the PDN gateway corresponding to the PDN connection of the UE in the first communication system, the first core network device sends the PDN to the PDN gateway only after determining that the address of the PDN gateway is reachable. Context information of the connection, so that the PDN gateway establishes a connection with the PDN in the second communication system
  • the PDU session should be in order to move the UE from the first communication system to the second communication system, thereby avoiding the problem of prolonged processing during the movement because the PDN gateway is unreachable during the movement.
  • the first core network device acquires an address of the PDN gateway corresponding to the PDN connection of the UE in the first communications system, where the first core network device receives the UE at the first Context information of the PDN connection in the communication system (for example, the context information may be sent by the mobility management entity MME in the 4G communication system to the AMF); the first core network device acquires the PDN corresponding to the PDN connection according to the context information.
  • the address of the gateway that is, the address of the corresponding PDN gateway that contains the PDN connection in the context information, and the address may be an IP address or a full-name domain name FQDN.
  • the first core network device may obtain the address of the corresponding PDN gateway by using the context information of the PDN connection.
  • the method before the first core network device sends the first information to the second core network device of the second communications system, the method further includes: determining, by the first core network device, the PDN gateway Correspondingly, the first core network device sends the first information to the second core network device of the second communication system, specifically: when the address of the PDN gateway is unreachable, the first core network device is second. The core network device sends the first information.
  • the method further includes: determining, by the first core network device, whether the UE is in a roaming state according to an address of the PDN gateway; where, when the UE is in a roaming state, the first The information also includes a Data Network Name (DNN) and a Public Land Mobile Network (PLMN) identity.
  • the first core network device may send the DNN and the PLMN identifier of the network where the UE is located to the second core network device when the UE is in the roaming state, so that the second core network device determines the roaming Ground.
  • the second information further includes an address of the v-SMF
  • the v-SMF is a session management network element when the UE is roaming.
  • the second core network device may further send the first core network device to the address of the v-SMF where the UE is in the roaming manner, so that the first core network device passes the The v-SMF communicates with the PDN gateway corresponding to the PDN connection.
  • the method further includes: the first core network device receiving the EPS included in the PDN connection sent by the PDN gateway And the first core network device generates the EPS bearer setup information according to the identifier set of the EPS bearer, and sends the EPS bearer setup information to the core network device of the first communications system, where the EPS bearer setup information is used by the first communications system.
  • the core network device determines an EPS bearer that the UE successfully switches.
  • the first core network device may notify the core network device of the first communication system by using the EPS bearer setup information and the EPS bearer successfully switched by the UE.
  • the first communication system is a fourth generation 4G communication system
  • the second communication system is a fifth generation 5G communication system.
  • a user equipment includes: a processing unit, configured to establish at least one PDN connection in the first communication system; and a processing unit, configured to generate first PDU session state information, first The PDU session state information is used to indicate a PDU session corresponding to the PDN connection supported by the second communication system in the at least one PDN connection; the sending unit is configured to send a registration message to the core network device of the second communication system, in the registration message The first PDU session state information is included, and the receiving unit is configured to receive a registration accept message sent by the core network device of the second communication system.
  • the sending unit is further configured to: go to the first communications system
  • the core network device sends a first message, where the first message is used to establish a PDN connection in the first communication system
  • the receiving unit is further configured to receive the first information, where the first information is used by the UE to determine whether the PDN connection supports or does not support moving to Second communication system.
  • the processing unit is further configured to: generate the first PDU session state information by using an identifier of the PDU session corresponding to the PDN connection that supports moving to the second communications system.
  • the processing unit is further configured to: set an identifier of the PDN connection that supports moving to the second communication system as an identifier of the PDU session; or move to the second according to the support.
  • the identity of the PDN connection of the communication system obtains the identity of the PDU session.
  • the first information includes first indication information, where the first indication information is used to indicate that the PDN connection of the UE supports moving to the second communications system
  • the processing unit is further configured to: Determining, according to the first indication information, that the PDN connection supports moving to the second communication system; or, the first information includes second indication information, where the second indication information is used to indicate that the PDN connection of the UE does not support moving to the second communication system, the processing unit And being further configured to: determine, according to the second indication information, that the PDN connection does not support moving to the second communication system.
  • the first information includes session information of a PDU session corresponding to the PDN connection, where the session information includes at least one of the following information: a session AMBR, a QoS rule, an SSC mode, or a PDU.
  • the session identifier the processing unit, is further configured to: determine, according to the session information, that the PDN connection supports moving to the second communication system.
  • the first information is included in a protocol configuration option PCO.
  • the processing unit is further configured to: determine that the moving from the first communications system to the second communications system is required.
  • the registration accept message includes the second PDU session state information, where the second PDU session state information is used to indicate the PDU session used by the UE in the second communications system, and the processing unit And for: deleting other PDN connections except the PDN connection corresponding to the PDU session indicated by the second PDU session state information.
  • the first communication system is a fourth generation 4G communication system
  • the second communication system is a fifth generation 5G communication system.
  • the fifth aspect provides a core network device, where the core network device is a core network device of the first communication system, and includes: a processing unit, configured to determine that the user equipment UE needs to move to the second communication system; and a sending unit, configured to The core network device of the second communication system sends context information of the PDN connection supported by the UE to the second communication system, and the context information of the PDN connection is used by the core network device of the second communication system to establish a PDU session corresponding to the PDN connection.
  • the core network device of the second communication system In order to move the UE from the first communication system to the second communication system, the core network device of the second communication system establishes a PDU session corresponding to the PDN connection in the second communication system according to the context information of the PDN connection.
  • the processing unit before the sending unit sends the context information of the PDN connection supported by the UE to the second communication system to the core network device of the second communication system, the processing unit is further configured to: : Determining that the PDN connection supports or does not support moving to the second communication system.
  • the core network device further includes: a receiving unit, configured to receive a handover request sent by the base station, and a processing unit, configured to determine, according to the handover request, that the UE needs to move to Second communication system.
  • the processing unit is further configured to: delete the PDN connection on the UE that does not support moving to the second communication system.
  • the receiving unit is further configured to receive a context request message
  • the processing unit is further configured to: according to the sender of the context request message, belong to the second communications system, determine that the UE needs to move to Second communication system.
  • the context request message includes the second information, where the second information is used to indicate that the sender of the context request message belongs to the second communications system; or the context request message includes the GUTI of the UE.
  • the processing unit is further configured to: the core network device of the first communication system is mapped according to the GUTI of the UE according to the GUTI of the second communication system, and the sender of the Context Request message belongs to the second communication system.
  • the processing unit is further configured to: determine that the PDN connection in the second communication system is not supported on the UE, and the sending unit is further configured to send a session deletion request, the session The delete request contains an action indicator.
  • the first communication system is a fourth generation 4G communication system
  • the second communication system is a fifth generation 5G communication system.
  • the sixth aspect provides a core network device, where the core network device is a first core network device of the second communication system, and includes: an acquiring unit, configured to acquire a PDN corresponding to the PDN connection of the user equipment UE in the first communication system An address of the gateway, where the sending unit is configured to send the first information to the second core network device of the second communications system, where the first information includes an address of the PDN gateway, and the acquiring unit is further configured to receive the second The second information is used to indicate that the address of the PDN gateway is reachable or unreachable.
  • the sending unit is further configured to: when the address of the PDN gateway is reachable, send the context information of the PDN connection to the PDN gateway, and the context information of the PDN connection.
  • a PDN gateway is used to establish a PDU session corresponding to the PDN connection in the second communication system to implement the UE moving from the first communication system to the second communication system.
  • the acquiring unit is further configured to: receive context information of the PDN connection established by the UE in the first communications system, and acquire, according to the context information, the PDN gateway corresponding to the PDN connection address.
  • the core network device before the sending unit sends the first information to the second core network device of the second communications system, the core network device further includes: a processing unit, configured to determine the PDN gateway The address is reachable.
  • the sending unit is further configured to send the first information to the second core network device when the address of the PDN gateway is unreachable.
  • the processing unit is further configured to: determine, according to an address of the PDN gateway, whether the UE is in a roaming state; where, when the UE is in a roaming state, the first information further includes Data Network Name (DNN) and Public Land Mobile Network (PLMN) identity.
  • DNN Data Network Name
  • PLMN Public Land Mobile Network
  • the second information further includes an address of the v-SMF, and the v-SMF is a session management network element when the UE is roaming.
  • the sending unit after the sending unit sends the context information of the PDN connection to the PDN gateway, the acquiring unit is further configured to receive the identifier set of the EPS bearer included in the PDN connection sent by the PDN gateway; The unit is further configured to generate an EPS bearer setup information according to the identifier set of the EPS bearer, and the sending unit is further configured to send, by the core network device of the first communications system, the EPS bearer setup information, and the EPS bearer setup information. The core network device used by the first communication system determines the EPS bearer that the UE successfully switches.
  • a seventh aspect of the present application provides a user equipment, including a memory, a processor, a communication interface, and a bus, wherein the memory stores code and data, and the processor, the memory, and the communication interface are connected by a bus, and the processor runs in the memory.
  • the code causes the user equipment to perform the inter-communication system movement method provided by the first aspect or any of the possible implementations of the first aspect.
  • An eighth aspect of the present application provides a core network device, which is a core network device of a first communication system, including: a memory, a processor, a communication interface, and a bus, storing code and data in the memory, a processor, and a memory.
  • the communication interface is connected by a bus, and the code in the processor running the memory causes the core network device to perform the inter-communication system movement method provided by the second aspect or any possible implementation manner of the second aspect.
  • a ninth aspect of the present application provides a core network device, where the core network device is a core network device of the second communication system, including: a memory, a processor, a communication interface, and a bus, the memory stores code and data, the processor, the memory, and The communication interface is connected by a bus, and the processor runs the code in the memory to cause the core network device to perform the inter-communication system movement method provided by any of the above third aspect or the third aspect.
  • a further aspect of the present application provides a system, comprising: a user equipment, a core network entity of a first communication system, and a core network entity of a second communication system; wherein the user equipment is any of the fourth aspect or the fourth aspect a possible implementation, or the user equipment provided by the seventh aspect; and/or the core network entity of the first communication system is any one of the possible implementations of the fifth aspect or the fifth aspect, or the eighth aspect
  • the core network device; and/or the core network entity of the second communication system is any one of the possible implementation manners of the sixth aspect or the sixth aspect, or the core network device provided by the ninth aspect.
  • Yet another aspect of the present application provides a computer readable storage medium having stored therein instructions that, when executed on a computer, cause the computer to perform the methods described in the above aspects.
  • Yet another aspect of the present application provides a computer program product comprising instructions which, when run on a computer, cause the computer to perform the methods described in the various aspects above.
  • FIG. 1 is a system architecture diagram of a communication system according to an embodiment of the present application.
  • FIG. 2 is a schematic structural diagram of a user equipment according to an embodiment of the present disclosure
  • FIG. 3 is a flowchart of a method for moving between communication systems according to an embodiment of the present application
  • FIG. 4 is a flowchart of establishing a PDN connection according to an embodiment of the present application.
  • FIG. 5 is a schematic diagram 1 of a UE moving from 4G to a 5G communication system according to an embodiment of the present disclosure
  • FIG. 6 is a second example of a UE moving from 4G to a 5G communication system according to an embodiment of the present disclosure
  • FIG. 7 is a flowchart of another method for moving between communication systems according to an embodiment of the present application.
  • FIG. 8 is a third example of a UE moving from 4G to a 5G communication system according to an embodiment of the present application.
  • FIG. 9 is a flowchart of still another UE moving to a second communication system according to an embodiment of the present application.
  • FIG. 10 is a fourth example of a UE moving from 4G to a 5G communication system according to an embodiment of the present application.
  • FIG. 11 is a schematic diagram 5 of a UE moving from 4G to a 5G communication system according to an embodiment of the present disclosure
  • FIG. 12 is a schematic structural diagram of a user equipment according to an embodiment of the present disclosure.
  • FIG. 13 is a schematic structural diagram of another user equipment according to an embodiment of the present disclosure.
  • FIG. 14 is a schematic structural diagram of a core network device of a first communication system according to an embodiment of the present disclosure.
  • FIG. 15 is a schematic structural diagram of another core network device of a first communication system according to an embodiment of the present disclosure.
  • FIG. 16 is a schematic structural diagram of a core network device of a second communication system according to an embodiment of the present disclosure.
  • FIG. 17 is a schematic structural diagram of a core network device of another second communication system according to an embodiment of the present disclosure.
  • PDN Protocol Data Network
  • APN Access Point Name
  • PDN connection context includes the IP address used by the PDN connection, the APN, the PGW address, and the context information of each EPS bearer.
  • PDU Session A combination of a set of QoS flows established on a UE within a second communication system (eg, a 5G network) having the same IP address and data network name (Data Network Name, DNN).
  • a QoS flow refers to a data transmission channel within a second communication system (eg, within a 5G network).
  • a PDU session is identified by an IP address and a DNN.
  • PDU Session Context Includes the IP address, APN, SMF, and UPF address used by the PDU session, as well as context information for each QoS flow.
  • PCO Protocol Configuration Option
  • the system architecture of the communication system to which the embodiment of the present application is applied is as shown in FIG. 1.
  • the system architecture includes a first communication system and a second communication system.
  • the first communication system is a 4G communication system
  • the second communication system is used.
  • a 5G communication system will be described as an example.
  • the communication system includes a UE, an evolved UMTS Terrestrial Radio Access Network (E-UERAN), a mobility management entity MME, a Serving Gateway (S-GW), and a user plane.
  • PPF User Plane Function
  • PGW-U PDN Gateway-User plane
  • SMF Session Management Function
  • PGW PDN Gateway-Control plane
  • PCF Policy and Charging Rules Function
  • HSS Home Subscriber Server
  • UDM Unified Data Management
  • UDM Unified Data Management
  • AMF Access and Mobility Management Function
  • 5G-RAN 5G Radio Access Network
  • the E-UTRAN is a 4G-side base station, and the UE can access the 4G communication system through the base station;
  • the 5G-RAN is a 5G-side base station, and the UE can access the 5G communication system through the base station, and the 5G-RAN can be further evolved by the E-UTRAN.
  • the UE can access the base station of the 5G communication system through the base station, or 5G-RAN can It is a base station dedicated to the UE accessing the 5G communication system.
  • the MME is a 4G core network device, which is responsible for authentication, authorization, mobility management, and session management of the UE.
  • the associated EPS bearer ID (LBI) of the UE in the 4G PDN connection is allocated by the device.
  • the S-GW is a 4G core network device (core network gateway), which is responsible for data forwarding, downlink data storage, and the like.
  • UPF+PGW-U is the core network equipment shared by 4G and 5G, that is, the core network equipment of 4G and 5G, including the functions of UPF and PGW-U.
  • the UPF is a user plane device of the 5G core network, and provides a user plane service for the PDU session of the UE, and is an interface gateway between the operator network and the external network.
  • the PGW-U is a user plane device of the 4G core network, and provides user plane services for the PDN connection of the UE, and is an interface gateway between the operator network and the external network.
  • UPF+PGW-U can also be called PGW-U+UPF, as long as it is a device that includes UPF and PGW-U functions.
  • SMF+PGW-C is the core network equipment shared by 4G and 5G, that is, the core network equipment of 4G and 5G, including the functions of SMF and PGW-C.
  • the SMF is a control plane device of the 5G core network, and provides a control plane service for the PDU session of the UE; manages the 5G PDU session, manages the 5G QoS, and is responsible for allocating an IP address for the UE, and is responsible for selecting the UPF for the UE.
  • the PGW-C is a control plane device of the 4G core network, and provides user plane services for the PDN connection of the UE. It is responsible for allocating an IP address for the UE and establishing an EPS bearer for the UE.
  • SMF+PGW-C can also be called PGW-C+SMF, as long as it is a device that includes SMF and PGW-C functions.
  • PCF+PCRF is a core network device shared by 4G and 5G, that is, 4G and 5G core network devices, including PCF and PCRF.
  • the PCRF is a 4G core network device, and is responsible for generating a policy for a user to establish a data bearer.
  • PCF is a 5G core network device, similar to the PCRF function.
  • PCF+PCRF may also be referred to as PCRF+PCF, as long as it is a device containing PCF and PCRF functions.
  • UDM+HSS is a core network device shared by 4G and 5G, that is, 4G and 5G core network devices, including HSS and UDM.
  • the HSS is a 4G core network device and is used to store subscription data of the user.
  • the SDM is a 5G core network device and is used to store user subscription data.
  • UDM+HSS can also be called HSS+UDM, as long as it is a device that includes both HSS and UDM functions.
  • AMF is a 5G core network device, which is used to authenticate and authorize users and manage user mobility.
  • the N26 interface is an interface between the MME and the AMF. Currently, the interface is optional.
  • the UE context can be transmitted through the N26 interface.
  • the PDN connection established by the UE in the 4G network can be seamlessly transferred to the 5G network, the MME selects 5G and 4G for the UE.
  • the network element SMF+PGW-C seamless transfer means that the IP address is unchanged and the PGW-C is unchanged.
  • FIG. 2 is a schematic structural diagram of a user equipment according to an embodiment of the present disclosure.
  • the user equipment may be a mobile phone, a tablet computer, a notebook computer, an UMPC (Ultra-mobile Personal Computer), a netbook, or a PDA (Personal Digital). Assistant, personal digital assistant), mobile phone chip (eg, modem modem chip), mobile station, wearable device, in-vehicle device, or terminal device, and the like.
  • the devices mentioned above are collectively referred to as user equipments or UEs in this application. .
  • the embodiment of the present application is described by using a UE as a mobile phone.
  • the UE includes an RF (radio frequency) circuit 210, a memory 220, an input unit 230, a display unit 240, a gravity sensor 250, and an audio circuit 260.
  • the processor 270, and the power supply 280 and the like are included in the mobile phone in conjunction with Figure 2:
  • the RF circuit 210 can be used for receiving and transmitting signals during the transmission or reception of information or during a call. Specifically, after receiving the downlink information of the base station, the processor 270 processes the uplink information. In addition, the uplink data is sent to the base station. Generally, RF circuit 210 includes, but is not limited to, an antenna, at least one amplifier, a transceiver, a coupler, a Low Noise Amplifier (LNA), a duplexer, and the like. In addition, RF circuitry 210 can also communicate with the network and other devices via wireless communication.
  • the processor 270 may include an application processor (AP) and a modem processor. The operating system, user interface, and application of the mobile phone run processing on the AP, and the communication function is processed on the modem processor.
  • AP application processor
  • the memory 220 can be used to store software programs and modules, and the processor 270 executes various functional applications and data processing of the mobile phone by running software programs and modules stored in the memory 220.
  • the memory 220 may mainly include a storage program area and a storage data area, wherein the storage program area may store an operating system, an application required for at least one function (for example, a call function, a video playing function, etc.), and the like; the storage data area may be stored according to Data created by the use of the mobile phone (eg, phone book, photo album, etc.).
  • memory 220 can include high speed random access memory, and can also include non-volatile memory, such as at least one magnetic disk storage device, flash memory device, or other volatile solid state storage device.
  • the input unit 230 can be configured to receive input numeric or character information and to generate key signal inputs related to user settings and function controls of the handset.
  • the input unit 230 may include a touch panel 231 and other input devices 232.
  • the touch panel 231 also referred to as a touch screen, can collect touch operations on or near the user (eg, the user uses a finger, a stylus, or the like on the touch panel 231 or near the touch panel 231. Operation) and drive the corresponding connection device according to a preset program.
  • the touch panel 231 can include two parts: a touch detection device and a touch controller.
  • the touch detection device detects the touch orientation of the user, and detects a signal brought by the touch operation, and transmits the signal to the touch controller; the touch controller receives the touch information from the touch detection device, converts the touch information into contact coordinates, and sends the touch information.
  • the processor 270 is provided and can receive commands from the processor 270 and execute them.
  • the touch panel 231 can be implemented in various types such as resistive, capacitive, infrared, and surface acoustic waves.
  • the input unit 230 may also include other input devices 232.
  • other input devices 232 may include, but are not limited to, one or more of a physical keyboard, function keys (such as volume control buttons, power switch buttons, etc.), trackballs, mice, joysticks, and the like.
  • the display unit 240 can be used to display information input by the user or information provided to the user as well as various menus of the mobile phone.
  • the display unit 240 may include a display panel 241.
  • the display panel 241 may be configured in the form of a liquid crystal display (LCD), an organic light-emitting diode (OLED), or the like.
  • the touch panel 231 can cover the display panel 241. When the touch panel 231 detects a touch operation on or near the touch panel 231, the touch panel 231 transmits to the processor 270 to determine the type of the touch event, and then the processor 270 according to the touch event. The type provides a corresponding visual output on display panel 241.
  • the touch panel 231 and the display panel 241 are used as two independent components to implement the input and output functions of the mobile phone in FIG. 2, in some embodiments, the touch panel 231 may be integrated with the display panel 241. Realize the input and output functions of the phone.
  • Gravity sensor 250 which can detect the phone in all directions (usually three axes) The magnitude of the acceleration, the magnitude and direction of gravity can be detected at rest, and can be used to identify the gesture of the mobile phone (such as horizontal and vertical screen switching, related games, magnetometer attitude calibration), vibration recognition related functions (such as pedometer, tap) Wait.
  • the phone can also include other sensors, such as light sensors.
  • the light sensor can include an ambient light sensor and a proximity light sensor.
  • the ambient light sensor can adjust the brightness of the display panel 241 according to the brightness of the ambient light; the proximity light sensor can detect whether an object approaches or contacts the mobile phone, and can close the display panel 241 and/or the backlight when the mobile phone moves to the ear.
  • Other sensors such as gyroscopes, barometers, hygrometers, thermometers, and infrared sensors that can be configured on the mobile phone are not described here.
  • Audio circuitry 260, speaker 261, microphone 262 can provide an audio interface between the user and the handset.
  • the audio circuit 260 can transmit the converted electrical data of the received audio data to the speaker 261, and convert it into a sound signal output by the speaker 261.
  • the microphone 262 converts the collected sound signal into an electrical signal, and the audio circuit 260 After receiving, it is converted into audio data, and then the audio data is output to the RF circuit 210 for transmission to, for example, another mobile phone, or the audio data is output to the memory 220 for further processing.
  • the processor 270 is the control center of the handset, and connects various portions of the entire handset using various interfaces and lines, by executing or executing software programs and/or modules stored in the memory 220, and invoking data stored in the memory 220, executing The phone's various functions and processing data, so that the overall monitoring of the phone.
  • the processor 270 may include one or more processing units; preferably, the processor 270 may integrate an application processor and a modem processor, where the application processor mainly processes an operating system, a user interface, an application, and the like.
  • the modem processor primarily handles wireless communications. It can be understood that the above modem processor may not be integrated into the processor 270.
  • the handset also includes a power source 280 (such as a battery) that powers the various components.
  • a power source can be logically coupled to the processor 270 via a power management system to manage functions such as charging, discharging, and power management through the power management system.
  • the mobile phone may further include a WiFi module, a Bluetooth module, and the like, and details are not described herein again. It will be understood by those skilled in the art that the structure of the handset shown in FIG. 2 does not constitute a limitation to the handset, and may include more or less components than those illustrated, or some components may be combined, or different component arrangements.
  • FIG. 3 is a flowchart of a method for moving between communication systems according to an embodiment of the present application. Referring to FIG. 3, the method includes the following steps.
  • S301 The UE establishes at least one PDN connection in the first communication system.
  • the at least one PDN connection may include one or more PDN connections.
  • the UE may establish a PDN connection in the first communication system by the following method, as described below.
  • the UE sends a first message to the core network device of the first communications system, where the first message is used to establish a PDN connection in the first communications system, where the first message may be an attach request or a PDN connection request.
  • the core network device of the first communication system receives the first message, it may be determined whether the PDN connection supports moving to the second communication system.
  • the core network device of the first communications system may determine whether the PDN connection supports moving to the second communications system according to the capability of the UE to report when registering, and the subscription data of the UE.
  • the core network device of the first communication system saves information that the PDN connection supports or does not support moving to the second communication system.
  • PDN connection support network interworking can be understood as the PDN connection can be moved (Move or Transfer) from the first communication system to the second communication system. That is, establishing a PDU corresponding to the PDN connection in the second communication system Session, the PDN connection and the PDU session satisfy one or more of the following conditions: the IP address of the PDU session is the same as the IP address of the PDN connection, the PDU session is the same as the PDN gateway to which the PDN is connected, and the DNN used by the PDU session is The APN used by the PDN connection corresponds, or the context of the PDU session corresponds to the context of the PDN connection.
  • the core network device of the first communication system selects the PDN gateway of the first communication system and the second communication system.
  • the core network device of the first communication system sends a session creation request to the PDN gateway and receives a session creation response returned by the PDN gateway.
  • the first information can be included in the session creation response returned by the PDN gateway.
  • the core network device of the first communication system may send the first information to the UE, so that the UE receives the first information, where the first information is used by the UE to determine whether the PDN connection supports or does not support moving to the second.
  • the communication system that is, the first information is used to notify the UE of the current PDN connection support or does not support network interworking.
  • the first information received by the UE may be sent by a PDN gateway (for example, a PGW), or may be sent by a core network device (for example, an AMF) in the second communication system.
  • the first information may include first indication information, where the first indication information is used to indicate that the PDN connection of the UE supports moving to the second communication system.
  • the first indication information when the UE receives the first information, it may be determined that the PDN connection supports moving to the second communication system according to the first indication information; or the first information includes second indication information, where the second indication information is used to indicate the The PDN connection of the UE does not support moving to the second communication system.
  • the UE receives the first information it may be determined according to the second indication information that the PDN connection does not support moving to the second communication system.
  • the first indication information or the second indication information may be used to explicitly indicate that the PDN connection supports or does not support moving to the second communication system.
  • the first indication information and the second indication information may be the same parameter, and are distinguished by different values; or, the first indication information and the second indication information may be different parameters.
  • the first information may include session information of the PDU session corresponding to the PDN connection, where the session information includes at least one of the following information: Aggregated Maximum Bit Rate (AMBR), QoS rule, and PDU session. Service and Session Continuity (SSC) mode or PDU session identification.
  • the UE receives the first information, it may be determined that the PDN connection supports moving to the second communication system according to the first information including the session information.
  • the session information is not included in the first information, it may be determined that the PDN connection does not support moving to the second communication system. Whether the PDN connection supports or does not support moving to the second communication system may be indicated by whether the first information includes the session information.
  • the first information may be included in a protocol configuration option PCO.
  • the first communication system may be a fourth generation (4G) communication system, and the second communication system may be a fifth generation (5G) communication system.
  • the core network device of the first communication system may be an MME, and the MME is taken as an example in FIG.
  • the core network device of the first communication system is the MME
  • the PDN gateway is the SMF+PGW-C.
  • the process of establishing the PDN connection in the 4G communication system of the UE may be as follows.
  • Figure 4 shows. Specifically, the method includes: S401.
  • the UE sends an attach request or a PDN connection request to the MME; S402.
  • the MME determines that the PDN connection can be moved to 5G, and then selects 4G and 5G SMF+PGW-C; S403.MME to S-GW Sending a create session request; S404.S-GW sends a create session request to SMF+PGW-C; S405.SMF+PGW-C sends a create session response to the S-GW, the create session response includes a PCO, and the PCO includes a notification
  • the current PDN connection of the UE supports network interworking information; S406.S-GW responds to the creation session Forwarding to the MME; S407.
  • the MME saves the information that the PDN connection supports network interworking; S408.
  • the MME sends an attach accept message or a PDN connection accept message including the PCO to the UE, where the PCO includes the PDN connection support for notifying the UE.
  • the information of the network interworking enables the PDN connection to be established, and the UE can also save the information that the PDN connection supports network interworking.
  • the PDN connection support network interworking is taken as an example, and the eNB is a base station in the 4G communication system.
  • the UE generates first PDU session state information, where the first PDU session state information is used to indicate a PDU session corresponding to a PDN connection supported by the second communication system in the at least one PDN connection.
  • the UE may generate the first PDU session state information by using the identifier of the PDU session corresponding to the PDN connection that is supported to the second communication system, that is, the UE may acquire at least one PDN connection and support moving to the second communication system.
  • the session identifier list of the PDU session corresponding to the PDN connection, and the first PDU session status information (PDU Session Status) is generated by using the session identifier list.
  • the first PDU session state information is used to indicate a PDU session corresponding to the PDN connection supported by the UE to the second communication system.
  • the first PDU session state information may only include an identifier of a PDU session corresponding to a PDN connection that supports moving to the second communication system; or, in a bitmap, a PDN connection phase that supports moving to the second communication system
  • the bit of the corresponding PDU session is set to 1 and the other bits are set to 0.
  • the PDU session IDs shown in Table 1 are 0 to 15.
  • the corresponding values are shown in Table 1.
  • the value of the PDU session identifiers 5 and 7 in the following Table 1 is 1, indicating that there is a corresponding PDU session.
  • the other values are 0, indicating that there is no corresponding PDU session identifier.
  • the UE When the UE acquires a session identifier list supporting a PDU session corresponding to a PDN connection of the second communication system, the UE may set an identifier of a PDN connection supporting the mobility to the second communication system to a session identifier of the corresponding PDU session. . Alternatively, the UE obtains the session identifier of its corresponding PDU session by some means according to the identifier of the PDN connection that supports moving to the second communication system.
  • the UE directly sets the PDN connection identifier to the PDU session identifier; the UE obtains the PDU session identifier after increasing or decreasing the PDN connection identifier by a specific value; or, the UE allocates the PDU session identifier during the establishment of the PDN connection, And sent to the SMF+PGW-C, the SMF+PGW-C returns to the UE for confirmation by the PCO, and the UE locally saves the correspondence between the PDN connection identifier and the PDU session identifier; or, the UE establishes the PDN connection process, the SMF+ The PGW-C requests the AMF to allocate the PDU session identifier, and the SMF+PGW-C sends the PDU session identifier to the UE through the PCO, and the UE locally saves the correspondence between the PDN connection identifier and the PDU session identifier.
  • the UE may determine whether the PDN connection saved in FIG. 4 supports the network interworking information. If a PDN connection supports network interworking, the PDN connection supports moving to the second communication system; if a PDN connection does not support network interworking, the PDN connection does not support moving to the second communication system.
  • the method may further include: The UE determines that it needs to move from the first communication system to the second communication system, that is, when the UE is in an idle state (Idle), the UE can actively initiate a process of moving from the first communication system to the second communication system, thereby acquiring more High network services.
  • Idle idle state
  • S303 The UE sends a registration message to the core network device of the second communications system, where the registration message includes the first PDU session state information.
  • the UE may send a registration message to the core network device of the second communication system, and send the first PDU session state information to the core network device of the second communication system by using the registration message. So that the core network device of the second communication system returns a registration accept message to the UE.
  • the core network device of the second communication system may be an AMF, that is, a core network device for managing mobility of the user in the second communication system, in FIG.
  • the core network device of the second communication system is an AMF as an example.
  • S304 The UE receives a registration accept message sent by the core network device of the second communications system, to implement the UE moving from the first communications system to the second communications system.
  • the UE When the UE receives the registration accept message, the UE has moved from the first communication system to the second communication system, since the UE is based on a PDU session corresponding to the PDN connection supporting the mobile to the second communication system in the at least one PDN connection. Transmitting a registration message to the core network device of the second communication system, that is, the UE moves from the first communication system to the second communication system based on the PDN connection supporting the movement to the second communication system, thereby avoiding the PDN during the movement
  • the gateway is unreachable, causing problems in processing during the move.
  • the registration accept message sent by the core network device of the second communication system to the UE may include second PDU session state information, where the second PDU session state information is used to indicate a PDU session used by the UE in the second communication system.
  • the PDU session indicated by the second PDU session state information belongs to a subset of the PDU session indicated by the first PDU session state information, that is, after the UE moves to the second communication system, the mobile control to the second communication system may be used.
  • the core network device of the second communication system can obtain the second PDU session state information by using two different methods.
  • the difference between the two methods is: in the first method, the core network device of the second communication system is from the first communication.
  • the core network device of the system (for example, the MME in 4G) obtains context information of all PDN connections on the UE; in the second method, the core network device of the second communication system is from the core network device of the first communication system (for example The MME in 4G only obtains the context information of the PDN connection supported on the UE to the second communication system, as described below.
  • the first method when the core network device of the second communication system receives the registration message, the core network device of the second communication system acquires context information of all PDN connections on the UE from the core network device of the first communication system, and according to The first PDU session state information included in the context information and the registration message determines that the PDN connection to the second communication system is supported. Further, the core network device of the second communication system may also obtain an address of the PDN gateway corresponding to the PDN connection that supports moving to the second communication system, and a session identifier of the PDU session corresponding to the PDN connection. Thereafter, the core network device of the second communication system can also obtain the session identifier of the PDN gateway corresponding to the PDN connection that supports moving to the second communication system to send its corresponding PDU session.
  • the identifier of all the PDN connections may be obtained according to the context information, and the identifier of each PDN connection is mapped to the session identifier of the PDU session.
  • the session identifier of the PDU session obtained by the mapping is in the first PDU session state information
  • the UE may also delete other PDN connections except the PDN connection corresponding to the PDU session indicated by the second PDU session state information, that is, delete all the UEs.
  • the context information of the PDN connection not transferred to the second communication system, the PDN connection not transferred to the second communication system may include a PDN connection that does not support moving to the second communication system, and support for moving to the second communication The system does not establish a PDN connection for the corresponding PDU session in the second communication system. For example, because the RAN side or the gateway side resources are insufficient, some PDU sessions are not successfully established, and the PDN connection corresponding to the unestablished successful PDU session needs to be deleted.
  • the core network device of the second communication system may be an AMF
  • the core network device of the first communication system may be an MME
  • the PDN gateway may be an SMF+PGW-C.
  • the UE can move to the second communication system through the flow shown in FIG.
  • the method includes: S501.
  • the UE determines that it needs to move from 4G to 5G, obtains a session identifier list that supports a PDU session corresponding to the PDN connection that is moved to the 5G, and generates a first PDU session state information by using the session identifier list; S502.
  • the AMF sends a registration request, where the registration request includes the first PDU session state information; S503.
  • the AMF sends a context request to the MME, where the context request is used to obtain context information of all PDN connections on the UE; S504.MME to AMF Returning a context response containing the context information; S505.
  • AMF sends an acknowledgment (ACK) to the MME; S506.
  • AMF sends an Update Location Request to the UDM+HSS; S507.
  • UDM+HSS returns an update location to the AMF S508.
  • UDM+HSS sends a Cancel Location to the MME; S509. MME returns a Cancel Location Confirmation to the UDM+HSS; S510.
  • the AMF determines to support moving to the second communication according to the context information and the first PDU session state information.
  • the AMF sends a registration accept message to the UE, where the registration accept message includes the second PDU session state information; S514.
  • the UE returns a registration complete message to the AMF; S515.
  • the UE may The second PDU session state information obtains an identifier (ID) of the corresponding PDN connection, and deletes the context information of the PDN connection other than the acquired ID of the PDN connection.
  • the second method when the core network device of the second communication system receives the registration message, the core network device of the second communication system acquires the PDN connection that only supports moving to the second communication system from the core network device of the first communication system. Context information, and based on the context information, determining a PDN connection that supports moving to the second communication system.
  • the core network device of the second communication system may send a context request message to the core network device of the first communication system, where the core network device of the first communication system belongs to the second communication system according to the sender of the context request message, and determines the The UE needs to move to the second communication system. Thereafter, the core network device of the first communication system can acquire a PDN connection supporting the move to the second communication system, and return context information supporting only the PDN connection moved to the second communication system to the core network device of the second communication system.
  • the core network device of the first communications system determines that the sender of the context request belongs to the second communications system, and includes: the context request message includes second information, where the second information is used to indicate that the sender of the context request message belongs to The second communication system, such that the core network device of the first communication system can determine that the sender of the context request belongs to the second communication system based on the second information.
  • the context request message includes a Globally Unique Temporary UE Identity (GUTI) of the UE, and the first communication system The core network device maps from the GUTI of the second communication system according to the GUTI of the UE, and indeed the sender of the context request message belongs to the second communication system.
  • GUI Globally Unique Temporary UE Identity
  • the UE may also delete other PDN connections except the PDN connection corresponding to the PDU session indicated by the second PDU session state information, that is, delete all the UEs.
  • the context information of the PDN connection not transferred to the second communication system, the PDN connection not transferred to the second communication system may include a PDN connection that does not support moving to the second communication system, and support for moving to the second communication The system does not establish a PDN connection for the corresponding PDU session in the second communication system. For example, because the RAN side or the gateway side resources are insufficient, some PDU sessions are not successfully established, and the PDN connection corresponding to the unestablished successful PDU session needs to be deleted. .
  • the core network device of the first communication system can also initiate a session deletion process.
  • the operation of the deletion session sent by the core network device of the first communication system does not carry an operation indication flag (Operation Indication Flag) for supporting the PDN connection to the second communication system.
  • the deletion session request sent by the core network device of the first communication system carries an operation indication flag.
  • the core network device of the second communication system may be an AMF
  • the core network device of the first communication system may be an MME
  • the PDN gateway may be an SMF+PGW-C.
  • the UE can move to the second communication system through the flow shown in FIG. 6.
  • the method includes: S601.
  • the UE determines that it needs to move from 4G to 5G, obtains a session identifier list that supports a PDU session corresponding to the PDN connection that is moved to the 5G, and generates a first PDU session state information by using the session identifier list; S602.
  • the AMF sends a registration request, where the registration request includes the first PDU session state information; S603.
  • the AMF sends a context request message to the MME, where the context request message carries a 5G indication, and the 5G indication is used to indicate the sender of the context request message. It belongs to the 5G communication system; S604.
  • the MME determines, according to the 5G indication, that the UE needs to move to the 5G communication system, thereby acquiring a PDN connection that supports moving to 5G; S605.
  • the MME returns a context response to the AMF, where the context response includes support for moving to 5G.
  • AMF sends a context confirmation (ACK) to the MME; S607.
  • AMF sends an Update Location Request to the UDM+HSS; S608.
  • UDM+HSS returns an update location response to the AMF; S609.
  • the UDM+HSS sends a Cancel Location message to the MME; S610.MME returns a Cancel Location Confirm message to the UDM+HSS; S611.
  • AMF sends an N11 message to the SMF+PGW-C, N 11 message carries an identifier (ID(s)) of the PDU session corresponding to the PDN connection that supports moving to 5G;
  • S612.SMF+PGW-C returns an N11 response to the AMF; S613.
  • AMF sends a registration accept message to the UE, the registration The receiving message includes the second PDU session state information; S614.
  • the UE returns a registration completion message to the AMF; S615.
  • the UE may obtain the identifier (ID) of the corresponding PDN connection according to the second PDU session state information, and delete the acquired PDN.
  • the MME obtains a PDN connection that does not support moving to the 5G; S617.
  • the MME sends a delete session request to the S-GW, where the delete session request carries an operation indication flag; S618. Carrying the operation indication flag, the S-GW sends a deletion session request to the SMF+PGW-C; S619.
  • the MME obtains a PDN connection that supports moving to the 5G; S620.
  • the MME sends a deletion session request to the S-GW, and the deletion session request does not carry Operation indicator.
  • the process of the MME initiating the deletion session in FIG. 6 includes steps S616-S620, where steps S616-S618 are used to delete the PDN connection that does not support moving to 5G, that is, delete the connection between the MME and the S-GW, and the S-GW and the SMF+.
  • steps S616-S618 are used to delete the PDN connection that does not support moving to 5G, that is, delete the connection between the MME and the S-GW, and the S-GW and the SMF+.
  • a connection between the PGW and the C; the S619-S620 is used to delete the PDN connection that supports moving to the 5G, that is, only the connection between the MME and the S-GW is deleted.
  • the UE may generate the first PDU session state information according to the PDN connection that is supported in the at least one PDN connection in the first communication system, and supports moving to the second communication system, and
  • the core network device of the second communication system sends a registration message including the first PDU session state information, and receives a registration accept message sent by the core network device of the second communication system, where the registration accept message includes indicating that the UE is in the second communication system.
  • the PDU session is used to move the UE from the first communication system to the second communication system.
  • the PDU session that the UE can use in the second communication system moves from the first communication system to the second communication system, thereby avoiding the PDN gateway being unavailable during the mobile process. Up, causing problems during processing during the move.
  • FIG. 7 is a flowchart of a method for moving between communication systems according to an embodiment of the present application. Referring to FIG. 7, the method includes the following steps.
  • the core network device of the first communication system determines that the UE needs to move to the second communication system.
  • the base station of the first communication system may actively send a handover request to the core network device of the first communication system when the UE is in the Connected state.
  • the handover request is for requesting handover of the UE to the second communication system such that the core network device of the first communication system can determine that the UE needs to move to the second communication system.
  • the core network device of the first communication system may belong to the second communication system according to the identifier of the target base station, and determine that the UE needs to move to the second communication system.
  • the first communication system may be a fourth generation (4G) communication system
  • the second communication system is a fifth generation (5G) communication system
  • the core network device of the first communication system may be an MME
  • the base station of the first communication system may For E-UTRAN, the MME is taken as an example in FIG.
  • the core network device of the first communication system sends the context information of the PDN connection supported by the UE to the second communication system to the core network device of the second communication system, where the context information of the PDN connection is used by the second communication system.
  • the core network device establishes a PDU session corresponding to the PDN connection.
  • the core network device of the first communication system may determine to support the PDN connection that is moved to the second communication system according to the PDN connection on the UE that is saved in advance or does not support the information moved to the second communication system. Thereafter, the core network device of the first communication system can transmit context information supporting only the PDN connection moving to the second communication system to the core network device of the second communication system.
  • the core network device of the second communication system may be an AMF, and the AMF is used as an example in FIG. 7 .
  • the PDN connection of the UE saved in the core network device of the first communication system, or the information that is not supported to be moved to the second communication system may be information that is saved by the UE when establishing the PDN connection, when the first
  • the core network device of the communication system is the MME
  • the core network device of the second communication system receives the context information of the PDN connection, and establishes a PDU session corresponding to the PDN connection according to the context information of the PDN connection, so as to implement the UE moving from the first communication system to the second communication system. .
  • the core network device of the second communication system may connect the PDN according to the address of the PDN gateway included in the context information of the PDN connection.
  • the context information is sent to the PDN gateway (eg, 4G and 5G core network devices SMF+PGW-C) to establish a PDU session corresponding to the PDN connection.
  • the address of the PDN gateway may be an IP address, or a Fully Qualified Domain Name (FQDN), FQDN. It can also be called a full name domain name.
  • FQDN Fully Qualified Domain Name
  • the context information of the PDN connection sent by the core network device of the second communication system to the PDN gateway may be the context of the PDN connection sent by the MME or a subset of the PDN connection context sent by the MME. For example, it can be the identity of the bearer contained in the PDN connection.
  • the core network device of the first communication system may send a handover command to the base station of the first communication system, so that the base station sends a handover command (Handover Command) to the UE.
  • the UE can move from the first communication system to the second communication system. Since the UE is moved from the first communication system to the second communication system based on the PDN connection supporting the movement to the second communication system, the problem of prolonged processing during the movement due to the unreachable PDN gateway during the movement is avoided. .
  • the core network device of the first communication system may also initiate a deletion process for deleting the PDN connection on the UE that does not support moving to the second communication system.
  • the core network device of the second communication system may be an AMF
  • the core network device of the first communication system may be an MME
  • the PDN gateway may be an SMF+PGW-C.
  • the UE can move to the second communication system through the flow shown in FIG. Specifically, the method includes: S801.
  • the E-UTRAN sends a handover request to the MME, where the handover request is used to request to switch the UE to 5G; and the S802.MME determines that the target system is 5G, that is, the UE needs to be moved to the 5G, according to the saved
  • the PDN connection on the UE supports the network interworking information, and only sends the context information supporting the PDN connection to the 5G to the AMF.
  • the S803 sends a Forward Relocation Request to the AMF, where the request includes the UE in the 4G network.
  • the information of the PDN connection established in the PDN connection information includes the IP address of the PDN gateway (for example, SMF+PGW-C) used by the PDN connection; S804.
  • AMF obtains the IP address of the PDN gateway in the PDN connection context, and The IP address sends a PDU session switching request, and the PDU session switching request includes context information of the PDN connection; S805.SMF+PGW-C sends a PDU session switching response message to the AMF, where the PDU session switching response message includes context information of the 5G PDU session.
  • the AMF sends a handover request (Handover Request) to the 5G RAN (the 5G base station), the handover request includes information of the PDU session; and the S807.5G RAN sends a handover request acknowledgement (ACK) to the AMF; S808.
  • AMF SMF+PGW-C sends a modify PDU session request; S809.SMF+PGW-C returns a modified PDU session response to the AMF; S810.AMF sends a Forward Relocation Response to the MME; S811.MME sends a handover to the E-UTRAN Command (Handover Command); S812. E-UTRAN sends a handover command to the UE; S813.
  • the UE sends a Handover Complete message to the 5G RAN; S814.5G RAN sends a Handover Notify to the AMF; S815.AMF
  • the MME sends a Forward Relocation Complete Notification (Sward).
  • S816. The MME initiates a process of deleting a PDN connection that does not support moving to the 5G.
  • the S817.MME sends a Forward Relocation Complete Notification (ACK) to the AMF.
  • ACK Forward Relocation Complete Notification
  • the core network device of the first communication system when determining that the UE needs to move to the second communication system, sends the UE to the core network device of the second communication system to support the mobile device.
  • the context information of the PDN connection of the second communication system, the context information of the PDN connection is used by the core network device of the second communication system to establish a PDU session corresponding to the PDN connection, and then the core network device of the first communication system sends the PDU session to the UE A command is switched to move the UE from the first communication system to the second communication system.
  • the UE is moved from the first communication system to the second communication system based on the PDU session corresponding to the PDN connection that supports moving to the second communication system, thereby avoiding processing during the mobile process because the PDN gateway is unreachable during the mobile process.
  • the problem is extended.
  • FIG. 9 is a flowchart of a method for moving between communication systems according to an embodiment of the present application. Referring to FIG. 9, the method includes the following steps.
  • the first core network device of the second communication system acquires an address of the PDN gateway corresponding to the PDN connection of the UE in the first communication system.
  • the PDN connection established by the UE in the first communication system may include one or more PDN connections, and the first core network device may acquire the address of the PDN gateway corresponding to each PDN connection.
  • the address of the PDN gateway may be an IP address of the PDN gateway or a Fully Qualified Domain Name (FQDN).
  • the FQDN may also be referred to as a full-name domain name.
  • the first core network device may receive the context information of the PDN connection established by the UE in the first communication system, and the established PDN connection may be one or multiple PDN connections.
  • the context information includes the address of the PDN gateway corresponding to all the PDN connections, so that the first core network device can obtain the address of the PDN gateway corresponding to each PDN connection from the context information.
  • the first communication system may be a 4G communication system
  • the second communication system may be a 5G communication system
  • the first core network device may be an AMF
  • the PDN gateway corresponding to the PDN connection may be a 4G and 5G core network device SMF+ PGW-C
  • the core network device in the first communication system is the MME
  • MME, AMF, and SMF+PGW-C are taken as an example in FIG.
  • the first core network device sends the first information to the second core network device of the second communication system, where the first information includes an address of the PDN gateway.
  • the second core network device is configured to determine, by the first core network device, whether the address of the PDN gateway is reachable.
  • the second core network device may be a Network Repository Function (NRF) in the 5G communication system, and the NRF is illustrated in FIG. 9 as an example.
  • NRF Network Repository Function
  • the first core network device may determine, by itself, whether the address of the PDN gateway is reachable, when the first core network device determines When the address of the PDN gateway is unreachable, the first core network device may send the first information including the address of the PDN gateway to the second core network device.
  • the first core network device determines that the address of the PDN gateway is unreachable, and the first core network device determines that the address of the PDN gateway is unreachable according to the saved information, or the first core network device cannot determine the address of the PDN gateway. Whether it is reachable.
  • the first core network device may further determine, according to the address of the PDN gateway, whether the UE is in a roaming state. When determining that the UE is in a roaming state, the first core network device may determine that the address of the PDN gateway is not available.
  • the first information sent to the second core network device may further include a data network name DNN and a Public Land Mobile Network (PLMN) identifier. That is, when the first core network device determines that the UE is in the roaming state, and the address of the PDN gateway is unreachable, the first information sent to the second core network device includes the following information: the address of the PDN gateway, the DNN, and the PLMN identifier. .
  • PLMN Public Land Mobile Network
  • the second core network device may determine the PDN network when the second core network device receives the first information. Whether the address of the PDN gateway is reachable or not, and the second information is used to indicate whether the address of the PDN gateway is reachable. When the second core network device determines that the address of the PDN gateway is reachable, then S904 is performed; otherwise, the UE cannot move from the first communication system to the second communication system, and the process ends.
  • the second information may include first indication information, where the first indication information is used to indicate that the address of the PDN gateway is reachable;
  • the second information may include the second indication information, where the second indication information is used to indicate that the address of the PDN gateway is unreachable.
  • the second information sent by the second core network device to the first core network device may further include the address of the v-SMF.
  • the v-SMF is a session management network element when the UE is roaming.
  • the PDN gateway receives the context information of the PDN connection, and establishes a PDU session corresponding to the PDN connection according to the context information of the PDN connection, so that the UE moves from the first communication system to the second communication information.
  • the first core network device may send the PDN connection context information to the PDN gateway, when the PDN gateway receives After the context information is obtained, a PDU session corresponding to the PDN connection can be established based on the context information. After establishing a PDU session corresponding to the PDN connection, the UE can move from the first communication system to the second communication system.
  • the PDN gateway may go to the first core.
  • the network device sends an identifier set of the EPS bearers included in the PDN connection.
  • the first core network device receives an identifier set (EBIs) of the EPS bearers included in the PDN connection, generates EPS bearer setup information according to the identifier set of the EPS bearer, and sends an EPS bearer to the core network device of the first communication system.
  • EBIs identifier set
  • the EPS bearer setup information is used by the core network device of the first communication system to determine the EPS bearer that the UE successfully switches.
  • the EPS bearer setup information may be an EPS Bearer Setup List.
  • the core network device of the first communications system receives the EPS bearer setup list, the EPS bearer that the UE successfully switches may be determined.
  • the first core network device may be an AMF
  • the second core network device may be an NRF, a PDN gateway.
  • the flow may be SMF+PGW-C, in conjunction with the method shown in FIG. 9, the flow of the UE moving from the first communication system to the second communication system may be as shown in FIG.
  • the method includes: S1001.
  • the E-UTRAN sends a handover request to the MME, where the handover request is used to request the UE to be handed over to the 5G; and the S1002.
  • the MME sends a Forward Relocation Request to the AMF, where the request includes the UE in the 4G.
  • the information of the PDN connection established in the network includes the IP address of the PDN gateway (for example, SMF+PGW-C) used by the PDN connection; S1003.AMF obtains the IP address of the PDN gateway in the PDN connection context, and judges The IP address Whether it is reachable, and whether the UE is in the roaming state (S1004 is performed when it is unreachable, and S1006 is performed when it is reachable); S1004.
  • the PDN gateway for example, SMF+PGW-C
  • AMF obtains the IP address of the PDN gateway in the PDN connection context, and judges The IP address Whether it is reachable, and whether the UE is in the roaming state (S1004 is performed when it is unreachable, and S1006 is performed when it is reachable); S1004.
  • the AMF sends an NF discovery request to the NRF (when it is determined that the UE is in a roaming state in S1003) When carrying DNN and PLMN); S1005.NRF returns NF discovery response to AMF (when the UE is in roaming state, it carries v-SMF address); S1006.AMF obtains IP address of PDN gateway in PDN connection context, and The PDU session switching request is sent by the IP address, and the PDU session switching request includes the context information of the PDN connection; S1007.SMF+PGW-C sends a PDU session switching response message to the AMF, where the PDU session switching response message includes context information of the 5G PDU session; S1008.
  • the AMF sends a handover request to the 5G RAN (ie, the 5G base station), where the handover request includes information of the PDU session; the S1009.5G RAN sends a handover request acknowledgement to the AMF; and the S1010.AMF sends a modify PDU session request to the SMF+PGW-C.
  • S1011.SMF+PGW-C determines that the UE needs to move from 4G to 5G, and then returns a modified PDU session response to the AMF, where the response carries the set of identifiers (EBIs) of the EPS bearers of the PDN connection corresponding to the PDU session; S1012.
  • EBIs set of identifiers
  • AMF collects all SMF+PGW After the message returned by -C, an EPS bearer setup list is generated; S1013.
  • AMF sends a forward migration response including an EPS bearer setup list to the MME; S1014.
  • MME sends a handover command to the E-UTRAN; S1015.
  • E-UTRAN sends a handover command to the UE S1016.
  • the UE sends a handover complete message to the 5G RAN; the S1017.5G RAN sends a handover notification to the AMF; S1018.
  • the AMF sends a Forward Migration Complete Notification to the MME; and S1019.
  • the MME sends a Forward Migration Complete Notification Confirmation to the AMF.
  • the first core network device may be an AMF
  • the second core network device may be an NRF, a PDN gateway.
  • the flow may be SMF+PGW-C, in conjunction with the method shown in FIG. 9, the flow of the UE moving from the first communication system to the second communication system may be as shown in FIG.
  • the method includes: S1101. The UE determines that it needs to move from 4G to 5G, obtains a session identifier list that supports a PDU session corresponding to the PDN connection that is moved to the 5G, and generates a first PDU session state information by using the session identifier list; S1102.
  • the AMF sends a registration request, where the registration request includes the first PDU session state information; S1103.
  • the AMF sends a context request to the MME, where the context request is used to obtain context information of all PDN connections on the UE; S1104.
  • the MME returns to the AMF to include the Context response of the context information; S1105.
  • the AMF sends a context confirmation to the MME; S1106.
  • the AMF sends an update location request to the UDM+HSS; S1107.
  • UDM+HSS returns an update location response to the AMF; S1108.
  • UDM+HSS sends a cancellation location to the MME; S1109.
  • the MME returns a canceled location confirmation to the UDM+HSS; the S1110.AMF obtains the PDN gateway's context information from the PDN gateway, and determines whether the IP address is reachable and whether the UE is in a roaming state. S1111, when it is reachable, step S1113) is performed; S1111.AMF sends an NF discovery request to the NRF (when the step is determined to be unreachable in step S1110 and the UE is in the roaming state, the DN is carried. N1 and PLMN); S1112.
  • the NRF returns an NF discovery response to the AMF (when the UE is in the roaming state, it carries the v-SMF address); S1113.AMF sends an N11 message to the SMF+PGW-C, and the N11 message carries the support to move to The identifier of the corresponding PDU session of the 5G PDN connection (ID(s)); S1114.SMF+PGW-C returns an N11 response to the AMF; S1115.AMF sends a registration accept message to the UE, and the registration accept message includes the second PDU Session state information; S1116. The UE returns a registration completion message to the AMF; S1117. The UE may obtain an identifier (ID) of the corresponding PDN connection according to the second PDU session state information, and delete other PDNs other than the acquired PDN connection ID. Context information for the connection.
  • first PDU session state information, the second PDU session state information, and the PDN connection that supports moving to 5G in the foregoing embodiment are consistent with the explanation in the embodiment in FIG. 5, and specifically refer to FIG. 5. The description of the embodiments in the present application is not described herein again.
  • the first core network device obtains the address of the PDN gateway corresponding to the PDN connection of the UE in the first communication system, only after determining that the address of the PDN gateway is reachable Transmitting the context information of the PDN connection to the PDN gateway, so that the PDN gateway establishes a PDU session corresponding to the PDN connection in the second communication system, so that the UE moves from the first communication system to the second communication system, Therefore, the problem that the processing is prolonged during the mobile process is avoided because the PDN gateway is unreachable during the mobile process.
  • each network element such as a user equipment, a core network device of the first communication system, and a core network device of the second communication system, etc., in order to implement the above functions, includes hardware structures and/or software corresponding to performing respective functions. Module.
  • the present application can be implemented in a combination of hardware or hardware and computer software in conjunction with the network elements and algorithm steps of the various examples described in the embodiments disclosed herein. Whether a function is implemented in hardware or computer software to drive hardware depends on the specific application and design constraints of the solution. A person skilled in the art can use different methods to implement the described functions for each particular application, but such implementation should not be considered to be beyond the scope of the present application.
  • the embodiment of the present application may perform functional module division on the user equipment, the core network device of the first communication system, and the core network device of the second communication system according to the foregoing method.
  • each functional module may be divided according to each function, or may be Two or more functions are integrated in one processing module.
  • the above integrated modules can be implemented in the form of hardware or in the form of software functional modules. It should be noted that the division of the module in the embodiment of the present application is schematic, and is only a logical function division, and the actual implementation may have another division manner.
  • FIG. 12 is a schematic diagram showing a possible structure of the user equipment involved in the foregoing embodiment, where the user equipment includes: a processing unit 1201, a sending unit 1202, and a receiving unit 1203. .
  • the processing unit 1201, the sending unit 1202, and the receiving unit 1203 are configured to support the user equipment to perform S301 in FIG. 3; the processing unit 1201 is further configured to support the user equipment to perform S302 in FIG. 3; the sending unit 1202 is further configured to support the user equipment.
  • S303 in FIG. 3 is executed; the receiving unit 1203 is further configured to support the user equipment to execute S304 in FIG. 3. All the related content of the steps involved in the foregoing method embodiments may be referred to the functional description of the corresponding functional modules, and details are not described herein again.
  • the processing unit 1201 may be a processor; the sending unit 1202 may be a transmitter, the receiving unit 1203 may be a receiver, and the transmitter and the receiver may form a communication interface.
  • FIG. 13 is a schematic diagram showing a possible logical structure of a user equipment involved in the foregoing embodiment provided by an embodiment of the present application.
  • the user equipment includes a processor 1302, a communication interface 1303, a memory 1301, and a bus 1304.
  • the processor 1302, the communication interface 1303, and the memory 1301 are connected to each other through a bus 1304.
  • the processor 1302 is configured to perform control management on actions of the user equipment, for example, the processor 1302 is configured to support the user equipment to perform S301 and S302 in FIG. 3, and/or used in the description herein. Other processes of technology.
  • the communication interface 1303 is configured to support user equipment for communication.
  • the memory 1301 is configured to store program codes and data of the user equipment.
  • the processor 1302 may be a central processing unit, a general purpose processor, a digital signal processor, an application specific integrated circuit, a field programmable gate array or other programmable logic device, a transistor logic device, and a hard Parts or any combination thereof. It is possible to implement or carry out the various illustrative logical blocks, modules and circuits described in connection with the present disclosure.
  • the processor may also be a combination of computing functions, for example, including one or more microprocessor combinations, combinations of digital signal processors and microprocessors, and the like.
  • the bus 1304 may be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus or the like.
  • PCI Peripheral Component Interconnect
  • EISA Extended Industry Standard Architecture
  • FIG. 14 is a schematic diagram showing a possible structure of a core network device of a first communication system involved in the foregoing embodiment, for example, the core network device may be 4G. MME in the network.
  • the core network device of the first communication system includes a processing unit 1401, a transmitting unit 1402, and a receiving unit 1403.
  • the processing unit 1401 is configured to support the core network device to perform S701 in FIG. 7;
  • the sending unit 1402 is configured to support the core network device to perform S702 in FIG. 7;
  • the processing unit 1401, the sending unit 1402, and the receiving unit 1403 are configured to support
  • the core network device performs S703 in Figure 7, and/or other processes for the techniques described herein. All the related content of the steps involved in the foregoing method embodiments may be referred to the functional description of the corresponding functional modules, and details are not described herein again.
  • the processing unit 1401 may be a processor
  • the sending unit 1402 may be a transmitter
  • the receiving unit 1403 may be a receiver
  • the receiver and the transmitter may form a communication interface.
  • FIG. 15 is a schematic diagram of a possible logical structure of a core network device of a first communication system involved in the foregoing embodiment provided by the embodiment of the present application.
  • the core network device may be an MME in a 4G network.
  • the core network device of the first communication system includes a processor 1502, a communication interface 1503, a memory 1501, and a bus 1504.
  • the processor 1502, the communication interface 1503, and the memory 1501 are connected to one another via a bus 1504.
  • the processor 1502 is configured to control and manage the action of the core network device.
  • the processor 1502 is configured to support the core network device to perform S701 in FIG. 7, and/or used in the description herein. Other processes of technology.
  • the communication interface 1503 is configured to support the core network device for communication.
  • the memory 1501 is configured to store program code and data of the core network device.
  • the processor 1502 can be a central processing unit, a general purpose processor, a digital signal processor, an application specific integrated circuit, a field programmable gate array or other programmable logic device, a transistor logic device, a hardware component, or any combination thereof. It is possible to implement or carry out the various illustrative logical blocks, modules and circuits described in connection with the present disclosure.
  • the processor may also be a combination of computing functions, for example, including one or more microprocessor combinations, combinations of digital signal processors and microprocessors, and the like.
  • the bus 1504 may be a peripheral component interconnect standard PCI bus or an extended industry standard architecture EISA bus or the like. The bus can be divided into an address bus, a data bus, a control bus, and the like. For ease of representation, only one thick line is shown in Figure 15, but it does not mean that there is only one bus or one type of bus.
  • FIG. 16 is a schematic diagram showing a possible structure of a core network device of a second communication system involved in the foregoing embodiment.
  • the core network device may be 5G. AMF in the network.
  • the core network device of the second communication system includes: an obtaining unit 1601, a transmitting unit 1602, and a processing unit 1603.
  • the obtaining unit 1601 is configured to support the core network device to perform S901 in FIG. 9 and to support the core network device to receive the second information sent by S903 in FIG. 9;
  • the sending unit 1602 is configured to support the core network device to perform FIG. S902 and S904;
  • acquisition unit 1601, transmission unit 1602 and processing unit 1603 is for supporting the core network device to perform S905 in FIG. 9, and/or other processes for the techniques described herein. All the related content of the steps involved in the foregoing method embodiments may be referred to the functional description of the corresponding functional modules, and details are not described herein again.
  • the processing unit 1603 may be a processor; the obtaining unit 1601 may be a receiver, the sending unit 1603 may be a transmitter, and the receiver and the receiver may constitute a communication interface.
  • FIG. 17 is a schematic diagram of a possible logical structure of a core network device of a second communication system involved in the foregoing embodiment provided by the embodiment of the present application.
  • the core network device may be an AMF in a 5G network.
  • the core network device of the second communication system includes a processor 1702, a communication interface 1703, a memory 1701, and a bus 1704.
  • the processor 1702, the communication interface 1703, and the memory 1701 are connected to one another via a bus 1704.
  • the processor 1702 is configured to control and manage the actions of the core network device, for example, the processor 1702 is configured to support the core network device to perform S905 in FIG. 9, and/or for the description herein. Other processes of technology.
  • the communication interface 1703 is configured to support the core network device for communication.
  • the memory 1701 is configured to store program code and data of the core network device.
  • the processor 1702 can be a central processing unit, a general purpose processor, a digital signal processor, an application specific integrated circuit, a field programmable gate array or other programmable logic device, a transistor logic device, a hardware component, or any combination thereof. It is possible to implement or carry out the various illustrative logical blocks, modules and circuits described in connection with the present disclosure.
  • the processor may also be a combination of computing functions, for example, including one or more microprocessor combinations, combinations of digital signal processors and microprocessors, and the like.
  • the bus 1704 can be a peripheral component interconnect standard PCI bus or an extended industry standard architecture EISA bus or the like. The bus can be divided into an address bus, a data bus, a control bus, and the like. For ease of representation, only one thick line is shown in Figure 17, but it does not mean that there is only one bus or one type of bus.
  • a readable storage medium comprising instructions for causing a device (which may be a microcontroller, a chip, etc.) or a processor to perform various embodiments of the present invention All or part of the steps of the method may specifically perform the steps of any one of the methods for moving between communication systems provided by any of the diagrams of FIG. 3 to FIG.
  • the foregoing readable storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk, and the like, which can store program codes. Medium.
  • a computer program product comprising computer executed instructions stored in a computer readable storage medium; at least one processor of the device can be a computer readable storage medium Reading the computer to execute the instruction, the at least one processor executing the computer to execute the instruction, so that the device performs all or part of the steps of the method according to various embodiments of the present invention, and specifically, the communication system provided by any of the diagrams of FIG. 3 to FIG. 11 may be executed. The step of moving any of the devices in the method.
  • a system is further provided, where the system includes a user equipment, a core network device of the first communication system, and a core network device of the second communication system; wherein the user equipment is the foregoing FIG. 2 12 or the user equipment provided in FIG. 13; and/or, the core network device of the first communication system is the core network device provided in FIG. 14 or FIG. 15 above; and/or the core network device of the second communication system is the above The core network device provided in Figure 16 or Figure 17.
  • the UE may move from the first communication system to the second communication system based on the PDU session corresponding to the PDN connection that supports moving to the second communication system, or determine the PDN of the UE. After the address of the corresponding PDN gateway is reachable, it is moved from the first communication system to the second communication system, thereby avoiding the problem that the UE is prone to processing during the mobile process because the PDN gateway is unreachable during the mobile process.

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Abstract

本申请实施例提供一种通信系统间移动方法及装置，涉及通信技术领域，解决了现有技术中UE移动过程中处理时延长的问题。所述方法包括：用户设备UE在第一通信系统内建立至少一个PDN连接；所述UE生成第一PDU会话状态信息，所述第一PDU会话状态信息用于指示所述至少一个PDN连接中支持移动至第二通信系统的PDN连接所对应的PDU会话；所述UE向所述第二通信系统的核心网设备发送注册消息，所述注册消息中包含所述第一PDU会话状态信息；所述UE接收所述第二通信系统的核心网设备发送的注册接受消息，以实现所述UE从所述第一通信系统移动至所述第二通信系统。

Description

一种通信系统间移动方法及装置 技术领域
本申请涉及通信技术领域，尤其涉及一种通信系统间移动方法及装置。
背景技术
随着通信技术的快速发展，出现了诸如智能手机、平板电脑、便携式设备等多种用户设备(User Equipment，UE)，这些UE可以同时支持不同代的移动通信网络，且可以在不同代的移动通信网络之间进行切换。第五代(5th Generation，5G)移动通信技术是对第四代(Forth Generation，4G)移动通信技术的延伸，具有高性能、低延迟和高容量等特性，其最高数据传输速度可达到数十Gbps以上，比现有的第4代(4G)网络的数据传输速度快1000倍。
现有技术中，UE可以在4G网络中建立协议数据网络(Protocol Data Network，PDN)连接，当UE需要切换至5G网络中时，4G网络中的移动性管理实体(MME)可以向5G网络的接入与移动性管理功能(Access and Mobility Management Function，AMF)发送该UE的上下文(Context)信息，该上下文信息中包括该UE在4G网络内建立的PDN连接信息，该PDN连接信息中包括PDN网关(PGW)的IP地址。当AMF接收到该上下文信息后，AMF向IP地址所指示的PGW发送切换流程，以将UE切换至5G网络中。
但是，由于4G网络和5G网络中PDN网关的差异，有的PDN连接可以切换至5G网络，有的PDN连接不能切换至5G网络。当PDN连接不能切换至5G网络时，AMF向IP地址所指示的PGW发送的切换流程不可达，从而导致AMF等待较长的时间，进而增加了UE移动至5G的处理时延。
发明内容
本申请的实施例提供一种通信系统间移动方法及装置，用于将UE从第一通信系统移动至第二通信系统，解决了现有技术中UE移动过程中处理时延较长的问题。
为达到上述目的，本申请的实施例采用如下技术方案：
第一方面，提供一种通信系统间移动方法，该方法包括：用户设备UE在第一通信系统内建立至少一个PDN连接，比如，第一通信系统为4G通信系统；该UE生成第一PDU会话状态信息，第一PDU会话状态信息用于指示该至少一个PDN连接中支持移动至第二通信系统的PDN连接所对应的PDU会话，可选的，第一PDU会话状态信息为PDU会话的标识；该UE向第二通信系统的核心网设备发送注册消息，注册消息中包含第一PDU会话状态信息(比如，第二通信系统为5G通信系统，该核心网设备为5G中的接入与移动性管理功能AMF)；该UE接收第二通信系统的核心网设备发送的注册接受消息。
上述技术方案中，该UE通过至少一个PDN中支持移动至第二通信系统的PDN连接生成第一PDU会话状态信息，并通过注册消息将第一PDU会话状态信息发送给第二通信系统的核心网设备，以使第二通信系统的核心网设备向该UE发送注册接受 消息，从而将该UE基于支持移动至第二通信系统的PDN连接所对应的PDU会话从第一通信系统移动至第二通信系统，避免了该UE在移动过程中因为PDN网关不可达，而造成移动过程中处理时延长的问题。
在第一方面的第一种可能的实现方式中，该UE在第一通信系统内建立至少一个PDN连接，包括：该UE向第一通信系统的核心网设备(比如，该核心网设备为4G网络中的移动性管理实体MME)发送第一消息，第一消息用于该UE在第一通信系统内建立PDN连接，可选的，第一消息可以为附着请求或者PDN连接请求；该UE接收第一信息，第一信息用于该UE确定PDN连接支持或不支持移动至第二通信系统，该第一信息可以包含在附着接受消息或者PDN连接接受消息中。上述可能的实现方式中，该UE可以在建立PDN连接过程中，获取每个PDN连接支持或不支持移动至第二通信系统的信息，从而基于该信息可以使该UE准确的从至少一个PDN连接中确定出支持移动至第二通信系统的PDN连接。
在第一方面的第一种可能的实现方式中，该UE生成第一PDU会话状态信息，包括：该UE使用支持移动至第二通信系统的PDN连接相对应的PDU会话的标识生成第一PDU会话状态信息。上述可能的实现方式中，该UE可以通过对应的PDU会话的标识生成第一PDU会话状态信息，从而可以简单有效的通过标识指示PDU会话。
在第一方面的第一种可能的实现方式中，该UE使用支持移动至第二通信系统的PDN连接相对应的PDU会话的标识生成第一PDU会话状态信息，包括：该UE根据支持移动至第二通信系统的PDN连接的标识获得PDU会话的标识。可选的，即按照一定的规则处理PDN连接的标识，以获得其对应的PDU会话的标识，将PDN连接的标识增加或者减小固定数值，得到对应的PDN会话的标识。
在第一方面的第一种可能的实现方式中，该UE根据支持移动至第二通信系统的PDN连接的标识获得PDU会话的标识，包括：该UE将支持移动至第二通信系统的PDN连接的标识设置为PDU会话的标识，即将PDN连接的标识作为其对应PDU会话的标识。上述可能的实现方式中，提供了几种基于PDN连接的标识生成其对应的PDU会话的标识的方法。
在第一方面的第一种可能的实现方式中，第一信息包括第一指示信息，第一指示信息用于指示该UE的PDN连接支持移动至第二通信系统，该方法还包括：该UE根据第一指示信息确定PDN连接支持移动至第二通信系统；或者，第一信息包括第二指示信息，第二指示信息用于指示该UE的PDN连接不支持移动至第二通信系统，该方法还包括：该UE根据第二指示信息确定PDN连接不支持移动至第二通信系统。上述可能的实现方式中，该UE可以简单有效的通过第一信息包括不同的指示信息，确定该PDN连接支持或不支持移动至第二通信系统。
在第一方面的第一种可能的实现方式中，第一信息包括PDN连接对应的PDU会话的会话信息，该会话信息包括以下信息中的至少一项：会话AMBR、QoS规则、SSC模式或PDU会话标识，该方法还包括：该UE根据会话信息，确定PDN连接支持移动至第二通信系统。上述可能的实现方式中，提供了一种指示方法，即该UE可以通过第一信息中包含PDU会话的会话信息确定该UE支持支持移动至第二通信系统。
结合第一方面，在第一方面的第一种可能的实现方式中，第一信息包含在协议配置选项PCO中，其中，PCO用于UE与PDN网关间进行信息传递的参数，UE与PDN网关之间的其他设备不解析该PCO。上述可能的实现方式中，将第一信息包含在PCO中，可以减少网络中信令的交互。
在第一方面的第一种可能的实现方式中，该UE生成第一PDU会话状态信息之前，该方法还包括：该UE确定需要从第一通信系统移动至第二通信系统，即该UE处于空闲态时，该UE可以主动发起从第一通信系统移动至第二通信系统的流程。
在第一方面的第一种可能的实现方式中，注册接受消息中包含第二PDU会话状态信息，第二PDU会话状态信息用于指示该UE在第二通信系统中使用的PDU会话，即第二通信系统中的核心网设备从第一PDU会话状态信息所指示的PDU会话中确定的该UE在第二通信系统中使用的PDU会话；该方法还包括：该UE删除与第二PDU会话状态信息所指示的PDU会话相对应的PDN连接之外的其他PDN连接，即该UE可以删除未转移到第二通信系统中的PDN连接的上下文信息。上述可能的实现方式中，该UE在移动至第二通信系统后，通过删除未转移到第二通信系统中的PDN连接的上下文信息可以保证该UE上使用的连接和存储的上下文信息的一致性，同时还可以节省一定的存储空间。
在第一方面的第一种可能的实现方式中，第一通信系统为第四代4G通信系统，第二通信系统为第五代5G通信系统。
第二方面，提供一种通信系统间移动方法，该方法包括：第一通信系统的核心网设备确定用户设备UE需要移动至第二通信系统；第一通信系统的核心网设备向第二通信系统的核心网设备发送该UE上支持移动至第二通信系统的PDN连接的上下文信息，该PDN连接的上下文信息用于第二通信系统的核心网设备建立与PDN连接对应的PDU会话，以使该UE从第一通信系统移动至第二通信系统时，第二通信系统的核心网设备根据该PDN连接的上下文信息，在第二通信系统中建立与该PDN连接对应的PDU会话。
上述技术方案中，第一通信系统的核心网设备在确定UE需要移动至第二通信系统后，将该UE上支持移动至第二通信系统的PDN连接的上下文信息发送给第二通信系统的核心网设备，以使第二通信系统的核心网设备建立与PDN连接对应的PDU会话，从而该UE是基于支持移动至第二通信系统的PDN连接对应的PDU会话从第一通信系统向第二通信系统移动，避免了在移动过程中因为PDN网关不可达，而造成移动过程中处理时延长的问题。
在第二方面的第一种可能的实现方式中，第一通信系统的核心网设备向第二通信系统的核心网设备发送该UE上支持移动至第二通信系统的PDN连接的上下文信息之前，该方法还包括：第一通信系统的核心网设备确定PDN连接支持或不支持移动至第二通信系统。可选的，第一通信系统的核心网设备可以在建立PDN连接过程中，获取每个PDN连接支持或不支持移动至第二通信系统的信息，从而基于该信息确定该UE上支持移动至第二通信系统的PDN连接。
在第二方面的第一种可能的实现方式中，第一通信系统的核心网设备确定用户设备UE需要移动至第二通信系统，包括：第一通信系统的核心网设备接收基站发送的 切换请求；第一通信系统的核心网设备根据切换请求，确定该UE需要移动至第二通信系统。上述可能的实现方式中，当该UE处于连接态时，第一通信系统的基站可以向第一通信系统的核心网设备发送切换请求，以将该UE从第一通信系统切换至第二通信系统。
在第二方面的第一种可能的实现方式中，该方法还包括：第一通信系统的核心网设备删除该UE上不支持移动至第二通信系统的PDN连接。上述可能的实现方式中，在该UE移动至第二通信系统后，第一通信系统可以删除未转移到第二通信系统中的PDN连接可以节省一定的传输资源。
在第二方面的第一种可能的实现方式中，第一通信系统的核心网设备确定用户设备UE需要移动至第二通信系统，包括：第一通信系统的核心网设备接收上下文请求消息；第一通信系统的核心网设备根据上下文请求消息的发送方属于第二通信系统，确定该UE需要移动至第二通信系统。上述可能的实现方式中，第一通信系统的核心网设备可以通过上下文请求消息的发送方属于第二通信系统，确定该UE需要移动至第二通信系统。
在第二方面的第一种可能的实现方式中，上下文请求消息包含第二信息，第二信息用于指示上下文请求消息的发送方属于第二通信系统；或者，上下文请求消息包含该UE的GUTI，该方法还包括：第一通信系统的核心网设备根据该UE的GUTI是从第二通信系统的GUTI映射的，确定上下文请求消息的发送方属于第二通信系统。上述可能的实现方式中，第一通信系统的核心网设备可以通过上下文请求消息中的信息快速准确的确定其发送方属于第二通信系统。
在第二方面的第一种可能的实现方式中，该方法还包括：第一通信系统的核心网设备确定该UE上不支持移动至第二通信系统中的PDN连接，第一通信系统的核心网设备发送会话删除请求，会话删除请求包含操作指示标志。上述可能的实现方式中，通过在会话删除请求中包含操作指示标志，以指示会话删除请求的接收方删除相应的连接，从而可以节省一定的网络资源。
在第二方面的第一种可能的实现方式中，第一通信系统为第四代4G通信系统，第二通信系统为第五代5G通信系统。
第三方面，提供一种系统间移动方法，该方法包括：第二通信系统的第一核心网设备(比如，5G通信系统中的接入与移动性管理功能AMF)获取用户设备UE在第一通信系统中的PDN连接对应的PDN网关的地址；第一核心网设备向第二通信系统的第二核心网设备(比如，网络存储功能实体NRF)发送第一信息，第一信息包括PDN网关的地址；第一核心网设备接收第二核心网设备发送的第二信息，第二信息用于指示PDN网关的地址可达或不可达；当该PDN网关的地址可达时，则第一核心网设备向PDN网关发送PDN连接的上下文信息，PDN连接的上下文信息用于PDN网关在第二通信系统内建立与PDN连接对应的PDU会话，以实现该UE从第一通信系统移动至第二通信系统。
上述技术方案中，第一核心网设备在获取该UE在第一通信系统中的PDN连接对应的PDN网关的地址后，只有在确定该PDN网关的地址可达时，才向该PDN网关发送PDN连接的上下文信息，以使该PDN网关在第二通信系统内建立与该PDN连接对 应的PDU会话，以使该UE从第一通信系统移动至第二通信系统，从而避免了在移动过程中因为PDN网关不可达，而造成移动过程中处理时延长的问题。
在第三方面的第一种可能的实现方式中，第一核心网设备获取UE在第一通信系统中的PDN连接对应的PDN网关的地址，包括：第一核心网设备接收该UE在第一通信系统中的该PDN连接的上下文信息(比如，该上下文信息可以是4G通信系统中的移动性管理实体MME发送给AMF的)；第一核心网设备根据该上下文信息，获取PDN连接对应的PDN网关的地址，即该上下文信息中包含PDN连接的对应的PDN网关的地址，该地址可以是IP地址或者全称域名FQDN。上述可能的实现方式中，第一核心网设备可以通过PDN连接的上下文信息获取对应的PDN网关的地址。
在第三方面的第一种可能的实现方式中，第一核心网设备向第二通信系统的第二核心网设备发送第一信息之前，该方法还包括：第一核心网设备判断PDN网关的地址是否可达；相应的，第一核心网设备向第二通信系统的第二核心网设备发送第一信息，具体为：当PDN网关的地址不可达时，则第一核心网设备向第二核心网设备发送第一信息。
在第三方面的第一种可能的实现方式中，该方法还包括：第一核心网设备根据PDN网关的地址，判断该UE是否处于漫游状态；其中，当该UE处于漫游状态时，第一信息还包括数据网络名称(DNN)和公共陆地移动网络(PLMN)标识。上述可能的实现方式中，第一核心网设备可以在该UE处于漫游状态时，将该UE所在网络的DNN和PLMN标识发送给第二核心网设备，以使第二核心网设备确定所在的漫游地。
在第三方面的第一种可能的实现方式中，第二信息还包括v-SMF的地址，v-SMF为该UE处于漫游时的会话管理网元。上述可能的实现方式中，在该UE处于漫游状态时，第二核心网设备还可以将该UE处于漫游地的v-SMF的地址发送第一核心网设备，以使第一核心网设备通过该v-SMF与PDN连接对应的PDN网关通信。
在第三方面的第一种可能的实现方式中，第一核心网设备向PDN网关发送PDN连接的上下文信息之后，该方法还包括：第一核心网设备接收PDN网关发送的PDN连接包括的EPS承载的标识集；第一核心网设备根据EPS承载的标识集，生成EPS承载建立信息，并向第一通信系统的核心网设备发送EPS承载建立信息，EPS承载建立信息用于第一通信系统的核心网设备确定该UE成功切换的EPS承载。上述可能的实现方式中，第一核心网设备可以通过EPS承载建立信息，将该UE成功切换的EPS承载通知给第一通信系统的核心网设备。
在第三方面的第一种可能的实现方式中，第一通信系统为第四代4G通信系统，第二通信系统为第五代5G通信系统。
第四方面，提供一种用户设备(UE)，该UE包括：处理单元，用于在第一通信系统内建立至少一个PDN连接；处理单元，还用于生成第一PDU会话状态信息，第一PDU会话状态信息用于指示该至少一个PDN连接中支持移动至第二通信系统的PDN连接所对应的PDU会话；发送单元，用于向第二通信系统的核心网设备发送注册消息，注册消息中包含第一PDU会话状态信息；接收单元，用于接收第二通信系统的核心网设备发送的注册接受消息。
在第四方面的第一种可能的实现方式中，发送单元，还用于：向第一通信系统的 核心网设备发送第一消息，第一消息用于在第一通信系统内建立PDN连接；接收单元，还用于接收第一信息，第一信息用于该UE确定PDN连接支持或不支持移动至第二通信系统。
在第四方面的第一种可能的实现方式中，处理单元，还用于：使用支持移动至第二通信系统的PDN连接相对应的PDU会话的标识生成第一PDU会话状态信息。
在第四方面的第一种可能的实现方式中，处理单元，还具体用于：将支持移动至第二通信系统的PDN连接的标识设置为PDU会话的标识；或者，根据支持移动至第二通信系统的PDN连接的标识获得PDU会话的标识。
在第四方面的第一种可能的实现方式中，第一信息包括第一指示信息，第一指示信息用于指示该UE的PDN连接支持移动至第二通信系统，处理单元，还用于：根据第一指示信息确定PDN连接支持移动至第二通信系统；或者，第一信息包括第二指示信息，第二指示信息用于指示该UE的PDN连接不支持移动至第二通信系统，处理单元，还用于：根据第二指示信息确定PDN连接不支持移动至第二通信系统。
在第四方面的第一种可能的实现方式中，第一信息包括PDN连接对应的PDU会话的会话信息，该会话信息包括以下信息中的至少一项：会话AMBR、QoS规则、SSC模式或PDU会话标识，处理单元，还用于：根据会话信息，确定PDN连接支持移动至第二通信系统。
结合第四方面，在第四方面的第一种可能的实现方式中，第一信息包含在协议配置选项PCO中。
在第四方面的第一种可能的实现方式中，处理单元，还用于：确定需要从第一通信系统移动至第二通信系统。
在第四方面的第一种可能的实现方式中，注册接受消息中包含第二PDU会话状态信息，第二PDU会话状态信息用于指示该UE在第二通信系统中使用的PDU会话，处理单元，还用于：删除与第二PDU会话状态信息所指示的PDU会话相对应的PDN连接之外的其他PDN连接。
在第四方面的第一种可能的实现方式中，第一通信系统为第四代4G通信系统，第二通信系统为第五代5G通信系统。
第五方面，提供一种核心网设备，该核心网设备为第一通信系统的核心网设备，包括：处理单元，用于确定用户设备UE需要移动至第二通信系统；发送单元，用于向第二通信系统的核心网设备发送该UE上支持移动至第二通信系统的PDN连接的上下文信息，PDN连接的上下文信息用于第二通信系统的核心网设备建立与PDN连接对应的PDU会话，以使该UE从第一通信系统移动至第二通信系统时，第二通信系统的核心网设备根据该PDN连接的上下文信息，在第二通信系统中建立与该PDN连接对应的PDU会话。
在第五方面的第一种可能的实现方式中，在发送单元向第二通信系统的核心网设备发送该UE上支持移动至第二通信系统的PDN连接的上下文信息之前，处理单元还用于：确定PDN连接支持或不支持移动至第二通信系统。
在第五方面的第一种可能的实现方式中，该核心网设备还包括：接收单元，用于接收基站发送的切换请求；处理单元，还用于根据切换请求，确定该UE需要移动至 第二通信系统。
在第五方面的第一种可能的实现方式中，处理单元，还用于：删除该UE上不支持移动至第二通信系统的PDN连接。
在第五方面的第一种可能的实现方式中，接收单元，还用于接收上下文请求消息；处理单元，还用于根据上下文请求消息的发送方属于第二通信系统，确定该UE需要移动至第二通信系统。
在第五方面的第一种可能的实现方式中，上下文请求消息包含第二信息，第二信息用于指示上下文请求消息的发送方属于第二通信系统；或者，上下文请求消息包含该UE的GUTI，处理单元，还用于：第一通信系统的核心网设备根据该UE的GUTI是从第二通信系统的GUTI映射的，确实上下文请求消息的发送方属于第二通信系统。
在第五方面的第一种可能的实现方式中，处理单元，还用于：确定该UE上不支持移动至第二通信系统中的PDN连接；发送单元，还用于发送会话删除请求，会话删除请求包含操作指示标志。
在第五方面的第一种可能的实现方式中，第一通信系统为第四代4G通信系统，第二通信系统为第五代5G通信系统。
第六方面，提供一种核心网设备，该核心网设备为第二通信系统的第一核心网设备，包括：获取单元，用于获取用户设备UE在第一通信系统中的PDN连接对应的PDN网关的地址；发送单元，用于向第二通信系统的第二核心网设备发送第一信息，第一信息包括PDN网关的地址；获取单元，还用于接收第二核心网设备发送的第二信息，第二信息用于指示PDN网关的地址可达或不可达；发送单元，还用于当该PDN网关的地址可达时，则向PDN网关发送PDN连接的上下文信息，PDN连接的上下文信息用于PDN网关在第二通信系统内建立与PDN连接对应的PDU会话，以实现该UE从第一通信系统移动至第二通信系统。
在第六方面的第一种可能的实现方式中，获取单元，还用于：接收该UE在第一通信系统中建立的PDN连接的上下文信息；根据上下文信息，获取PDN连接对应的PDN网关的地址。
在第六方面的第一种可能的实现方式中，在发送单元向第二通信系统的第二核心网设备发送第一信息之前，该核心网设备还包括：处理单元，用于判断PDN网关的地址是否可达；相应的，发送单元，还具体用于当PDN网关的地址不可达时，则向第二核心网设备发送第一信息。
在第六方面的第一种可能的实现方式中，处理单元，还用于：根据PDN网关的地址，判断该UE是否处于漫游状态；其中，当该UE处于漫游状态时，第一信息还包括数据网络名称(DNN)和公共陆地移动网络(PLMN)标识。
在第六方面的第一种可能的实现方式中，第二信息还包括v-SMF的地址，v-SMF为该UE处于漫游时的会话管理网元。
在第六方面的第一种可能的实现方式中，在发送单元向PDN网关发送PDN连接的上下文信息之后，获取单元，还用于接收PDN网关发送的PDN连接包括的EPS承载的标识集；处理单元，还用于根据EPS承载的标识集，生成EPS承载建立信息；发送单元，还用于第一通信系统的核心网设备发送EPS承载建立信息，EPS承载建立信 息用于第一通信系统的核心网设备确定该UE成功切换的EPS承载。
本申请的第七方面提供一种用户设备，该用户设备包括存储器、处理器、通信接口和总线，存储器中存储代码和数据，处理器、存储器和通信接口通过总线连接，处理器运行存储器中的代码使得用户设备执行上述第一方面或第一方面的任一种可能的实现方式所提供的通信系统间移动方法。
本申请的第八方面提供一种核心网设备，该核心网设备为第一通信系统的核心网设备，包括：存储器、处理器、通信接口和总线，存储器中存储代码和数据，处理器、存储器和通信接口通过总线连接，处理器运行存储器中的代码使得核心网设备执行上述第二方面或第二方面的任一种可能的实现方式所提供的通信系统间移动方法。
本申请的第九方面提供一种核心网设备，该核心网设备为第二通信系统的核心网设备包括：存储器、处理器、通信接口和总线，存储器中存储代码和数据，处理器、存储器和通信接口通过总线连接，处理器运行存储器中的代码使得核心网设备执行上述第三方面或第三方面的任一种可能的实现方式所提供的通信系统间移动方法。
本申请的又一方面提供一种系统，该系统包括用户设备、第一通信系统的核心网实体和第二通信系统的核心网实体；其中，用户设备为第四方面或第四方面任一种可能的实现方式、或者第七方面所提供的用户设备；和/或，第一通信系统的核心网实体为第五方面或第五方面任一种可能的实现方式、或者第八方面所提供的核心网设备；和/或，第二通信系统的核心网实体为第六方面或第六方面任一种可能的实现方式、或者第九方面所提供的核心网设备。
本申请的又一方面提供了一种计算机可读存储介质，所述计算机可读存储介质中存储有指令，当其在计算机上运行时，使得计算机执行上述各方面所述的方法。
本申请的又一方面提供了一种包含指令的计算机程序产品，当其在计算机上运行时，使得计算机执行上述各方面所述的方法。
可以理解地，上述提供的任一种通信移动方法的装置、计算机存储介质或者计算机程序产品均用于执行上文所提供的对应的方法，因此，其所能达到的有益效果可参考上文所提供的对应的方法中的有益效果，此处不再赘述。
附图说明
图1为本申请实施例提供的一种通信系统的系统架构图；
图2为本申请实施例提供的一种用户设备的结构示意图；
图3为本申请实施例提供的一种通信系统间移动方法的流程图；
图4为本申请实施例提供的一种建立PDN连接的流程图；
图5为本申请实施例提供的UE从4G移动至5G通信系统的示例图一；
图6为本申请实施例提供的UE从4G移动至5G通信系统的示例图二；
图7为本申请实施例提供的另一种通信系统间移动方法的流程图；
图8为本申请实施例提供的UE从4G移动至5G通信系统的示例图三；
图9为本申请实施例提供的又一种UE移动至第二通信系统的流程图；
图10为本申请实施例提供的UE从4G移动至5G通信系统的示例图四；
图11为本申请实施例提供的UE从4G移动至5G通信系统的示例图五；
图12为本申请实施例提供的一种用户设备的结构示意图；
图13为本申请实施例提供的另一种用户设备的结构示意图；
图14为本申请实施例提供的一种第一通信系统的核心网设备的结构示意图；
图15为本申请实施例提供的另一种第一通信系统的核心网设备的结构示意图；
图16为本申请实施例提供的一种第二通信系统的核心网设备的结构示意图；
图17为本申请实施例提供的另一种第二通信系统的核心网设备的结构示意图。
具体实施方式
在介绍本申请之前，首先对本申请实施例涉及的技术名词进行介绍说明。
协议数据网络(Protocol Data Network，PDN)连接(Connection或Connectivity)：第一通信系统内(比如，4G网络内)，UE上建立的一组EPS承载的组合，这些EPS承载具有相同的IP地址和接入点名称(Access Point Name，APN)，EPS承载是指在第一通信系统内(比如，4G网络内)的数据传输通道。在UE和网络侧，通过IP地址和APN来标识一个PDN连接。
PDN连接上下文(Context)：包括该PDN连接使用的IP地址，APN，PGW地址，以及每个EPS承载的上下文信息。
PDU会话(Session)：在第二通信系统(比如，5G网络)内，UE上建立的一组QoS流(flow)的组合，这些QoS流具有相同的IP地址和数据网络名称(Data Network Name，DNN)。QoS流是指在第二通信系统内(比如，5G网络内)的数据传输通道。在UE和网络侧，通过IP地址和DNN来标识一个PDU会话。
PDU会话上下文：包括该PDU会话使用的IP地址，APN，SMF及UPF地址，以及每个QoS流的上下文信息。
协议配置选项(Protocol Configuration Option，PCO)：UE与PDN网关(PDN Gateway，PGW)间进行信息传递的参数，移动性管理实体(Mobility Management Entity，MME)及基站不解析该PCO。
本申请的实施例所应用的通信系统的系统架构如图1所示，该系统架构包括第一通信系统和第二通信系统，图1中以第一通信系统为4G通信系统、第二通信系统为5G通信系统为例进行说明。
参见图1，该通信系统包括UE、演进的UMTS陆地无线接入网(Evolved UMTS Terrestrial Radio Access Network，E-UERAN)、移动性管理实体MME、服务网关(Serving Gateway，S-GW)、用户面功能(User Plane Function，UPF)+PDN网关的用户面(PDN Gateway-User plane，PGW-U)、会话管理功能(Session Management Function，SMF)+PDN网关的控制面(PDN Gateway-Control plane，PGW-C)、策略控制功能(policy control Function，PCF)+策略与计费规则功能单元(Policy and Charging Rules Function，PCRF)、归属签约服务器(Home Subscriber Server，HSS)+统一数据管理(Unified Data Management，UDM)、接入与移动性管理功能(Access and Mobility management Function，AMF)以及5G无线接入网(5G Radio Access Network，5G-RAN)。
其中，E-UTRAN为4G侧基站，UE通过该基站可以接入4G通信系统；5G-RAN为5G侧基站，UE通过该基站可以接入5G通信系统，5G-RAN可以是E-UTRAN进一步演进后的基站，UE可以通过该基站接入5G通信系统的基站，或5G-RAN可 以是专门用于UE接入5G通信系统的基站。
MME为4G核心网设备，负责对UE进行鉴权、授权，移动性管理，会话管理；UE在4G的PDN连接的关联EPS承载标识(Linked EPS Bearer ID，LBI)由该设备分配。
S-GW为4G核心网设备(核心网网关)，负责数据的转发，下行数据存储等。
UPF+PGW-U为4G和5G共用的核心网设备，即4G和5G合设的核心网设备，包括UPF和PGW-U的功能。其中，UPF是5G核心网的用户面设备，为UE的PDU会话提供用户面服务，是运营商网络与外部网络间的接口网关。PGW-U是4G核心网的用户面设备，为UE的PDN连接提供用户面服务，是运营商网络与外部网络间的接口网关。UPF+PGW-U也可被称为PGW-U+UPF，只要是包含UPF和PGW-U功能的设备均与本设备相同。
SMF+PGW-C为4G和5G共用的核心网设备，即4G和5G合设的核心网设备，包括SMF和PGW-C的功能。其中，SMF是5G核心网的控制面设备，为UE的PDU会话提供控制面服务；对5G的PDU会话进行管理，对5G的QoS进行管理，负责为UE分配IP地址，负责为UE选择UPF。PGW-C为4G核心网的控制面设备，为UE的PDN连接提供用户面服务；负责为UE分配IP地址，为UE建立EPS承载。SMF+PGW-C也可被称为PGW-C+SMF，只要是包含SMF和PGW-C功能的设备均与本设备相同。
PCF+PCRF为4G和5G共用的核心网设备，即4G和5G合设的核心网设备，包括PCF和PCRF。其中，PCRF为4G核心网设备，负责产生用户建立数据承载(Bearer)的策略。PCF为5G核心网设备，与PCRF功能类似。PCF+PCRF也可被称为PCRF+PCF，只要是包含PCF和PCRF功能的设备均与本设备相同。
UDM+HSS为4G和5G共用的核心网设备，即4G和5G合设的核心网设备，包括HSS和UDM。其中，HSS为4G核心网设备，用于保存用户的签约数据。SDM为5G核心网设备，用于保存用户的签约数据。UDM+HSS也可被称为HSS+UDM，只要是包含HSS和UDM功能的设备均与本设备相同。
AMF为5G核心网设备，用于对用户进行鉴权、授权，对用户的移动性进行管理。
N26接口是MME和AMF间的接口，目前该接口是可选的。当UE在4G和5G间移动时，通过N26接口可以进行UE上下文的传递，当UE在4G网络内建立的PDN连接可以被无缝转移到5G网络时，MME为UE选择5G与4G合设的网元SMF+PGW-C，无缝转移是指IP地址不变，PGW-C不变。
图2为本申请实施例提供的一种用户设备的结构示意图，该用户设备可以为手机、平板电脑、笔记本电脑、UMPC(Ultra-mobile Personal Computer，超级移动个人计算机)、上网本、PDA(Personal Digital Assistant，个人数字助理)、手机芯片(例如，调制解调器modem芯片)、移动台、可穿戴设备、车载设备、或终端设备等等。为方便描述，本申请中将上面提到的设备统称为用户设备或UE。。本申请实施例以UE为手机为例进行说明，该UE包括：RF(radio frequency，射频)电路210、存储器220、输入单元230、显示单元240、重力传感器250、音频电路260、 处理器270、以及电源280等部件。下面结合图2对手机的各个构成部件进行具体的介绍：
RF电路210可用于收发信息或通话过程中，信号的接收和发送，特别地，将基站的下行信息接收后，给处理器270处理；另外，将上行的数据发送给基站。通常，RF电路210包括但不限于天线、至少一个放大器、收发信机、耦合器、低噪声放大器(Low Noise Amplifier，LNA)、双工器等。此外，RF电路210还可以通过无线通信与网络和其他设备通信。其中，处理器270可以包括应用处理器(Application Processor，AP)和modem处理器，手机的操作系统、用户界面和应用程序等在AP上运行处理，通信功能在modem处理器上处理。
存储器220可用于存储软件程序以及模块，处理器270通过运行存储在存储器220的软件程序以及模块，从而执行手机的各种功能应用以及数据处理。存储器220可主要包括存储程序区和存储数据区，其中，存储程序区可存储操作系统、至少一个功能所需的应用程序(比如，通话功能、视频播放功能等)等；存储数据区可存储根据手机的使用所创建的数据(比如，电话本、相册等)等。此外，存储器220可以包括高速随机存取存储器，还可以包括非易失性存储器，例如至少一个磁盘存储器件、闪存器件、或其他易失性固态存储器件。
输入单元230可用于接收输入的数字或字符信息，以及产生与手机的用户设置以及功能控制有关的键信号输入。具体地，输入单元230可包括触控面板231以及其他输入设备232。触控面板231，也称为触摸屏，可收集用户在其上或附近的触摸操作(比如，用户使用手指、触笔等任何适合的物体或附件在触控面板231上或在触控面板231附近的操作)，并根据预先设定的程式驱动相应的连接装置。可选的，触控面板231可包括触摸检测装置和触摸控制器两个部分。其中，触摸检测装置检测用户的触摸方位，并检测触摸操作带来的信号，将信号传送给触摸控制器；触摸控制器从触摸检测装置上接收触摸信息，并将它转换成触点坐标，再送给处理器270，并能接收处理器270发来的命令并加以执行。此外，可以采用电阻式、电容式、红外线以及表面声波等多种类型实现触控面板231。除了触控面板231，输入单元230还可以包括其他输入设备232。具体地，其他输入设备232可以包括但不限于物理键盘、功能键(比如音量控制按键、电源开关按键等)、轨迹球、鼠标、操作杆等中的一种或多种。
显示单元240可用于显示由用户输入的信息或提供给用户的信息以及手机的各种菜单。显示单元240可包括显示面板241，可选的，可以采用液晶显示器(Liquid Crystal Display，LCD)、有机发光二极管(Organic Light-Emitting Diode，OLED)等形式来配置显示面板241。进一步的，触控面板231可覆盖显示面板241，当触控面板231检测到在其上或附近的触摸操作后，传送给处理器270以确定触摸事件的类型，随后处理器270根据触摸事件的类型在显示面板241上提供相应的视觉输出。虽然在图2中，触控面板231与显示面板241是作为两个独立的部件来实现手机的输入和输出功能，但是在某些实施例中，可以将触控面板231与显示面板241集成而实现手机的输入和输出功能。
重力传感器(gravity sensor)250，可以检测手机在各个方向上(一般为三轴) 加速度的大小，静止时可检测出重力的大小及方向，可用于识别手机姿态的应用(比如横竖屏切换、相关游戏、磁力计姿态校准)、振动识别相关功能(比如计步器、敲击)等。手机还可以包括其它传感器，比如光传感器。具体地，光传感器可包括环境光传感器及接近光传感器。其中，环境光传感器可根据环境光线的明暗来调节显示面板241的亮度；接近光传感器可以检测是否有物体靠近或接触手机，可在手机移动到耳边时，关闭显示面板241和/或背光。手机还可配置的陀螺仪、气压计、湿度计、温度计、红外线传感器等其他传感器，在此不再赘述。
音频电路260、扬声器261、麦克风262可提供用户与手机之间的音频接口。音频电路260可将接收到的音频数据转换后的电信号，传输到扬声器261，由扬声器261转换为声音信号输出；另一方面，麦克风262将收集的声音信号转换为电信号，由音频电路260接收后转换为音频数据，再将音频数据输出至RF电路210以发送给比如另一手机，或者将音频数据输出至存储器220以便进一步处理。
处理器270是手机的控制中心，利用各种接口和线路连接整个手机的各个部分，通过运行或执行存储在存储器220内的软件程序和/或模块，以及调用存储在存储器220内的数据，执行手机的各种功能和处理数据，从而对手机进行整体监控。可选的，处理器270可包括一个或多个处理单元；优选的，处理器270可集成应用处理器和调制解调处理器，其中，应用处理器主要处理操作系统、用户界面和应用程序等，调制解调处理器主要处理无线通信。可以理解的是，上述调制解调处理器也可以不集成到处理器270中。
手机还包括给各个部件供电的电源280(比如电池)，优选的，电源可以通过电源管理系统与处理器270逻辑相连，从而通过电源管理系统实现管理充电、放电、以及功耗管理等功能。
尽管未示出，手机还可以包括WiFi模块、蓝牙模块等，在此不再赘述。本领域技术人员可以理解，图2中示出的手机结构并不构成对手机的限定，可以包括比图示更多或更少的部件，或者组合某些部件，或者不同的部件布置。
图3为本申请实施例提供的一种通信系统间移动方法的流程图，参见图3，该方法包括以下几个步骤。
S301：UE在第一通信系统内建立至少一个PDN连接。
其中，至少一个PDN连接可以包括一个或者多个PDN连接，对于至少一个PDN连接中的每个PDN连接，该UE可以通过以下方法在第一通信系统内建立PDN连接，具体如下所述。
具体的，该UE向第一通信系统的核心网设备发送第一消息，第一消息用于在第一通信系统内建立PDN连接，第一消息可以为附着请求或者PDN连接请求。当第一通信系统的核心网设备接收到第一消息时，可以确定该PDN连接是否支持移动至第二通信系统。可选的，第一通信系统的核心网设备可以根据该UE在注册时上报的能力、以及该UE的签约数据等，确定该PDN连接是否支持移动至第二通信系统。第一通信系统的核心网设备保存该PDN连接支持或不支持移动至第二通信系统的信息。PDN连接支持网络互通可以理解为该PDN连接可以从第一通信系统移动(Move或Transfer)至第二通信系统。即在第二通信系统中建立一个与该PDN连接对应的PDU 会话，该PDN连接和PDU会话满足以下一个或多个条件：该PDU会话的IP地址与该PDN连接的IP地址相同，该PDU会话与该PDN连接的PDN网关相同，该PDU会话使用的DNN与该PDN连接使用的APN相对应，或者，该PDU会话的上下文与该PDN连接的上下文相对应。
当确定该PDN连接支持移动至第二通信系统时，则第一通信系统的核心网设备选择第一通信系统和第二通信系统合设的PDN网关。第一通信系统的核心网设备向该PDN网关发送会话创建请求，并接收该PDN网关返回的会话创建响应。PDN网关返回的会话创建响应中可以包含第一信息。之后，第一通信系统的核心网设备可以向该UE发送该第一信息，从而使该UE接收到该第一信息，第一信息用于该UE确定该PDN连接支持或不支持移动至第二通信系统，即第一信息用于通知该UE当前的PDN连接支持或不支持网络互通(Interworking)。其中，UE接收的第一信息，可以是由PDN网关(比如，PGW)发送的，也可以是由第二通信系统中的核心网设备(比如，AMF)发送的。
其中，第一信息中可以包括第一指示信息，第一指示信息用于指示该UE的PDN连接支持移动至第二通信系统。相应的，当该UE接收到第一信息时，可以根据第一指示信息确定该PDN连接支持移动至第二通信系统；或者，第一信息包括第二指示信息，第二指示信息用于指示该UE的PDN连接不支持移动至第二通信系统，相应的，当该UE接收到第一信息时，可以根据第二指示信息确定该PDN连接不支持移动至第二通信系统。通过第一指示信息或第二指示信息可以显性的指示该PDN连接支持或不支持移动至第二通信系统。在具体实现中，第一指示信息和第二指示信息可以是同一个参数，通过不同的取值进行区分；或者，第一指示信息和第二指示信息可以是不同的参数。
或者，第一信息可以包括该PDN连接对应的PDU会话的会话信息，该会话信息包括以下信息中的至少一项：会话聚合最大比特速率(Aggregated Maximum Bit Rate，AMBR)、QoS规则、PDU会话的业务和会话连续性(Service and Session Continuity，SSC)模式或PDU会话标识。相应的，当该UE接收到第一信息时，可以根据第一信息包含该会话信息，确定该PDN连接支持移动至第二通信系统。当第一信息中不包括该会话信息时，则可以确定该PDN连接不支持移动至第二通信系统。通过第一信息是否包括该会话信息，可以指示该PDN连接支持或不支持移动至第二通信系统。
可选的，第一信息可以包含在协议配置选项PCO中。第一通信系统可以为第四代(4G)通信系统，第二通信系统为第五代(5G)通信系统，第一通信系统的核心网设备可以为MME，图3中以为MME为例说明。
以图1所示的4G和5G通信系统为例，第一通信系统的核心网设备为MME，该PDN网关为SMF+PGW-C，则该UE在4G通信系统内建立PDN连接的过程可以如图4所示。具体包括：S401.该UE向MME发送附着请求或者PDN连接请求；S402.MME确定该PDN连接可移动至5G，则选择4G和5G合设的SMF+PGW-C；S403.MME向S-GW发送创建会话请求；S404.S-GW向SMF+PGW-C发送创建会话请求；S405.SMF+PGW-C向S-GW发送创建会话响应，该创建会话响应中包含PCO，该PCO中包含通知该UE当前的PDN连接支持网络互通的信息；S406.S-GW将该创建会话响应 转发给MME；S407.MME保存该PDN连接支持网络互通的信息；S408.MME向该UE发送包含PCO的附着接受消息或者PDN连接接受消息，其中，该PCO中包含通知该UE当前的PDN连接支持网络互通的信息，从而建立该PDN连接，同时该UE还可以保存该PDN连接支持网络互通的信息。图4中以该PDN连接支持网络互通为例进行说明，eNB为4G通信系统中的基站。
S302：该UE生成第一PDU会话状态信息，第一PDU会话状态信息用于指示至少一个PDN连接中支持移动至第二通信系统的PDN连接所对应的PDU会话。
其中，该UE可以使用支持移动至第二通信系统的PDN连接相对应的PDU会话的标识生成第一PDU会话状态信息，即该UE可以获取至少一个PDN连接中，支持移动至第二通信系统的PDN连接所对应的PDU会话的会话标识列表，使用该会话标识列表生成第一PDU会话状态信息(PDU Session Status)。该第一PDU会话状态信息用于指示该UE上支持移动至第二通信系统的PDN连接相对应的PDU会话。该第一PDU会话状态信息可以仅包括支持移动至第二通信系统的PDN连接相对应的PDU会话的标识；或者，在位图(bitmap)中，将支持移动至第二通信系统的PDN连接相对应的PDU会话的标识所在的位设置为1，其他位设置为0，如表1所示的PDU会话标识分别为0～15，其对应的取值具体如表1。下述表1中PDU会话标识为5和7对应的取值为1，表示存在对应的PDU会话，其他取值为0，表示都不存在对应PDU会话标识。
表1
PDU会话标识 7 6 5 4 3 2 1 0
取值 1 0 1 0 0 0 0 0
PDU会话标识 15 14 13 12 11 10 9 8
取值 0 0 0 0 0 0 0 0
该UE获取支持移动至第二通信系统的PDN连接所对应的PDU会话的会话标识列表时，该UE可以将支持移动至第二通信系统的PDN连接的标识设置为其对应的PDU会话的会话标识。或者，该UE根据支持移动至第二通信系统的PDN连接的标识，通过某种方式映射获得其对应的PDU会话的会话标识。例如，该UE直接将PDN连接标识设置为PDU会话标识；该UE将PDN连接标识增加或减小特定值后获得PDU会话标识；或者，该UE在建立PDN连接过程中，UE分配PDU会话标识，并发送给SMF+PGW-C，SMF+PGW-C通过PCO返回给UE进行确认，该UE本地保存PDN连接标识和PDU会话标识的对应关系；或者，该UE在建立PDN连接过程中，SMF+PGW-C请求AMF分配PDU会话标识，SMF+PGW-C通过PCO将该PDU会话标识发送给该UE，该UE本地保存PDN连接标识和PDU会话标识的对应关系。
另外，该UE确定至少一个PDN连接中支持移动至第二通信系统的PDN连接时，该UE可以通过上述图4中保存的PDN连接是否支持网络互通的信息进行确定。若一个PDN连接支持网络互通，则该PDN连接支持移动至第二通信系统；若一个PDN连接不支持网络互通，则该PDN连接不支持移动至第二通信系统。
进一步的，在该UE生成第一PDU会话状态信息之前，该方法还可以包括：该 UE确定需要从第一通信系统移动至第二通信系统，即当该UE处于空闲态(Idle)时，该UE可以主动地发起从第一通信系统移动至第二通信系统的流程，从而获取更高的网络服务。
S303：该UE向第二通信系统的核心网设备发送注册(Registration)消息，该注册消息中包含第一PDU会话状态信息。
当该UE生成第一PDU会话状态信息时，该UE可以向第二通信系统的核心网设备发送注册消息，并将第一PDU会话状态信息通过该注册消息发送给第二通信系统的核心网设备，以使第二通信系统的核心网设备向该UE返回注册接受消息。
其中，当第二通信系统为5G通信系统时，第二通信系统的核心网设备可以是AMF，即第二通信系统中用于对用户的移动性进行管理的核心网设备，图3中以第二通信系统的核心网设备为AMF为例说明。
S304：该UE接收第二通信系统的核心网设备发送的注册接受消息，以实现该UE从第一通信系统移动至第二通信系统。
当该UE接收到注册接受消息时，该UE已经从第一通信系统移动至第二通信系统，由于该UE是基于至少一个PDN连接中支持移动至第二通信系统的PDN连接所对应的PDU会话，向第二通信系统的核心网设备发送注册消息，即该UE基于支持移动至第二通信系统移动的PDN连接从第一通信系统向第二通信系统移动，从而避免了在移动过程中因为PDN网关不可达，而造成移动过程中处理时延长的问题。
进一步的，第二通信系统的核心网设备发送给该UE的注册接受消息可以包括第二PDU会话状态信息，第二PDU会话状态信息用于指示该UE在第二通信系统中使用的PDU会话。其中，第二PDU会话状态信息所指示的PDU会话属于第一PDU会话状态信息所指示的PDU会话的子集，即该UE移动至第二通信系统后，可以使用支持移动至第二通信系统的PDN连接所对应的PDU会话。
其中，第二通信系统的核心网设备可以通过以下两种不同的方法获取第二PDU会话状态信息，两种方法的区别在于：第一种方法中第二通信系统的核心网设备从第一通信系统的核心网设备(比如，4G中的MME)中获取了该UE上所有PDN连接的上下文信息；第二种方法中第二通信系统的核心网设备从第一通信系统的核心网设备(比如，4G中的MME)仅获取了该UE上支持移动至第二通信系统的PDN连接的上下文信息，具体如下所述。
第一种方法、当第二通信系统的核心网设备接收到注册消息时，第二通信系统的核心网设备从第一通信系统的核心网设备获取该UE上所有PDN连接的上下文信息，并根据上下文信息和注册消息中包含的第一PDU会话状态信息，确定支持移动至第二通信系统的PDN连接。进一步的，第二通信系统的核心网设备还可以获取支持移动至第二通信系统的PDN连接对应的PDN网关的地址，以及该PDN连接对应的PDU会话的会话标识。之后，第二通信系统的核心网设备还可以获得支持移动至第二通信系统的PDN连接对应的PDN网关发送其对应的PDU会话的会话标识。
可选的，第二通信系统的核心网设备确定支持移动至第二通信系统的PDN连接时，可以根据上下文信息获取所有PDN连接的标识，将每个PDN连接的标识映射为PDU会话的会话标识，当映射得到的PDU会话的会话标识在第一PDU会话状态信息 所指示的PDU会话中时，则确定该PDN连接支持移动至第二通信系统。
进一步的，当注册接受消息包括第二PDU会话状态信息时，该UE还可以删除与第二PDU会话状态信息所指示的PDU会话相对应的PDN连接之外的其他PDN连接，即删除该UE所有PDN连接中，未转移到第二通信系统中的PDN连接的上下文信息，未转移到第二通信系统的PDN连接可以包括不支持移动至第二通信系统的PDN连接、以及支持移动至第二通信系统但未在第二通信系统中建立对应PDU会话的PDN连接。例如，由于RAN侧或网关侧资源不足，一些PDU会话未建立成功，则未建立成功的PDU会话对应的PDN连接需要被删除。
以图1所示的4G和5G通信系统为例，则第二通信系统的核心网设备可以为AMF，第一通信系统的核心网设备可以为MME，PDN网关可以为SMF+PGW-C，该UE可以通过图5所示的流程移动至第二通信系统。具体包括：S501.该UE确定需要从4G移动至5G，获取支持移动至5G的PDN连接对应的PDU会话的会话标识列表，并使用会话标识列表生成第一PDU会话状态信息；S502.该UE向AMF发送注册请求，该注册请求中包括第一PDU会话状态信息；S503.AMF向MME发送上下文(Context)请求，该上下文请求用于获取该UE上所有PDN连接的上下文信息；S504.MME向AMF返回包含该上下文信息的上下文响应；S505.AMF向MME发送上下文确认(Acknowledgement，ACK)；S506.AMF向UDM+HSS发送更新位置请求(Update Location Request)；S507.UDM+HSS向AMF返回更新位置响应；S508.UDM+HSS向MME发送取消位置(Cancel Location)；S509.MME向UDM+HSS返回取消位置确认；S510.AMF根据上下文信息和第一PDU会话状态信息，确定支持移动至第二通信系统的PDN连接；S511.AMF向SMF+PGW-C发送N11消息，N11消息中携带支持移动至5G的PDN连接对应的PDU会话的标识(ID(s))；S512.SMF+PGW-C向AMF返回N11响应；S513.AMF向该UE发送注册接受消息，该注册接受消息中包含第二PDU会话状态信息；S514.该UE向AMF返回注册完成消息；S515.该UE可以根据第二PDU会话状态信息获得对应的PDN连接的标识(ID)，并删除获取的PDN连接的ID以外的其他PDN连接的上下文信息。
第二种方法、当第二通信系统的核心网设备接收到注册消息时，第二通信系统的核心网设备从第一通信系统的核心网设备获取仅支持移动至第二通信系统的PDN连接的上下文信息，并根据该上下文信息确定支持移动至第二通信系统的PDN连接。具体的，第二通信系统的核心网设备可以向第一通信系统的核心网设备发送上下文请求消息，第一通信系统的核心网设备根据该上下文请求消息的发送方属于第二通信系统，确定该UE需要移动至第二通信系统。之后，第一通信系统的核心网设备可以获取支持移动至第二通信系统的PDN连接，并向第二通信系统的核心网设备返回仅支持移动至第二通信系统的PDN连接的上下文信息。
可选的，第一通信系统的核心网设备确定该上下文请求的发送方属于第二通信系统，包括：该上下文请求消息包含第二信息，第二信息用于指示该上下文请求消息的发送方属于第二通信系统，从而第一通信系统的核心网设备可以根据第二信息确定该上下文请求的发送方属于第二通信系统。或者，该上下文请求消息包含该UE的全球唯一临时UE标识(Globally Unique Temporary UE Identity，GUTI)，第一通信系统的 核心网设备根据该UE的GUTI是从第二通信系统的GUTI映射的，确实该上下文请求消息的发送方属于第二通信系统。
进一步的，当注册接受消息包括第二PDU会话状态信息时，该UE还可以删除与第二PDU会话状态信息所指示的PDU会话相对应的PDN连接之外的其他PDN连接，即删除该UE所有PDN连接中，未转移到第二通信系统中的PDN连接的上下文信息，未转移到第二通信系统的PDN连接可以包括不支持移动至第二通信系统的PDN连接、以及支持移动至第二通信系统但未在第二通信系统中建立对应PDU会话的PDN连接。例如，由于RAN侧或网关侧资源不足，一些PDU会话未建立成功，则未建立成功的PDU会话对应的PDN连接需要被删除。。
此外，第一通信系统的核心网设备还可以发起会话删除流程。其中，对于支持移动至第二通信系统的PDN连接，第一通信系统的核心网设备发送的删除会话请求中不携带操作指示标志(Operation Indication Flag)。对于不支持移动至第二通信系统的PDN连接，第一通信系统的核心网设备发送的删除会话请求中携带操作指示标志。
以图1所示的4G和5G通信系统为例，则第二通信系统的核心网设备可以为AMF，第一通信系统的核心网设备可以为MME，PDN网关可以为SMF+PGW-C，该UE可以通过图6所示的流程移动至第二通信系统。具体包括：S601.该UE确定需要从4G移动至5G，获取支持移动至5G的PDN连接对应的PDU会话的会话标识列表，并使用会话标识列表生成第一PDU会话状态信息；S602.该UE向AMF发送注册请求，该注册请求中包括第一PDU会话状态信息；S603.AMF向MME发送上下文(Context)请求消息，该上下文请求消息中携带5G指示，5G指示用于指示上下文请求消息的发送方属于第5G通信系统；S604.MME根据5G指示确定该UE需要移动至5G通信系统，从而获取支持移动至5G的PDN连接；S605.MME向AMF返回上下文响应，该上下文响应中包含支持移动至5G的PDN连接的上下文信息；S606.AMF向MME发送上下文确认(ACK)；S607.AMF向UDM+HSS发送更新位置请求(Update Location Request)；S608.UDM+HSS向AMF返回更新位置响应；S609.UDM+HSS向MME发送取消位置(Cancel Location)消息；S610.MME向UDM+HSS返回取消位置确认消息；S611.AMF向SMF+PGW-C发送N11消息，N11消息中携带支持移动至5G的PDN连接对应的PDU会话的标识(ID(s))；S612.SMF+PGW-C向AMF返回N11响应；S613.AMF向该UE发送注册接受消息，该注册接受消息中包含第二PDU会话状态信息；S614.该UE向AMF返回注册完成消息；S615.该UE可以根据第二PDU会话状态信息获得对应的PDN连接的标识(ID)，并删除获取的PDN连接的ID以外的其他PDN连接的上下文信息；S616.MME获取不支持移动至5G的PDN连接；S617.MME向S-GW发送删除会话请求，该删除会话请求中携带操作指示标志；S618.由于携带操作指示标志，S-GW向SMF+PGW-C发送删除会话请求；S619.MME获取支持移动至5G的PDN连接；S620.MME向S-GW发送删除会话请求，该删除会话请求中不携带操作指示标志。图6中MME发起删除会话流程包括步骤S616-S620，其中步骤S616-S618用于删除不支持移动至5G的PDN连接，即删除MME与S-GW之间的连接、以及S-GW与SMF+PGW-C之间的连接；S619-S620用于删除支持移动至5G的PDN连接，即仅删除MME与S-GW之间的连接。
本申请实施例提供的通信系统间移动方法中，该UE可以根据第一通信系统内建立至少一个PDN连接中，支持移动至第二通信系统的PDN连接生成第一PDU会话状态信息，并向第二通信系统的核心网设备发送包含第一PDU会话状态信息的注册消息，接收第二通信系统的核心网设备发送的注册接受消息，注册接受消息中包含用于指示该UE在第二通信系统中使用的PDU会话，从而将该UE从第一通信系统移动至第二通信系统。由于该UE是基于第二通信系统的核心网设备确定的该UE可在第二通信系统使用的PDU会话从第一通信系统向第二通信系统移动，从而避免了在移动过程中因为PDN网关不可达，而造成移动过程中处理时延长的问题。
图7为本申请实施例提供的一种通信系统间移动方法的流程图，参见图7，该方法包括以下几个步骤。
S701：第一通信系统的核心网设备确定UE需要移动至第二通信系统。
其中，当该UE处于连接态(Connected)时，第一通信系统的基站可以主动的向第一通信系统的核心网设备发送切换请求，当第一通信系统的核心网设备接收到切换请求时，该切换请求用于请求将该UE切换至第二通信系统，从而第一通信系统的核心网设备可以确定该UE需要移动至第二通信系统。具体的，第一通信系统的核心网设备可以根据目标基站的标识属于第二通信系统，确定该UE需要移动至第二通信系统。
另外，第一通信系统可以为第四代(4G)通信系统，第二通信系统为第五代(5G)通信系统，第一通信系统的核心网设备可以为MME，第一通信系统的基站可以为E-UTRAN，图7中以MME为例说明。
S702：第一通信系统的核心网设备向第二通信系统的核心网设备发送该UE上支持移动至第二通信系统的PDN连接的上下文信息，该PDN连接的上下文信息用于第二通信系统的核心网设备建立与该PDN连接对应的PDU会话。
其中，第一通信系统的核心网设备可以根据事先保存的该UE上的PDN连接支持或不支持移动至第二通信系统的信息，确定支持移动至第二通信系统的PDN连接。之后，第一通信系统的核心网设备可以向第二通信系统的核心网设备发送仅支持移动至第二通信系统的PDN连接的上下文信息。可选的，第二通信系统的核心网设备可以为AMF，图7中以AMF为例说明。
可选的，第一通信系统的核心网设备中事先保存的该UE的PDN连接支持或不支持移动至第二通信系统的信息，可以是该UE在建立PDN连接时保存的信息，当第一通信系统的核心网设备为MME时，则具体可以参见图4中的描述。
S703：第二通信系统的核心网设备接收该PDN连接的上下文信息，并根据该PDN连接的上下文信息建立该PDN连接对应的PDU会话，以实现该UE从第一通信系统移动至第二通信系统。
其中，当第二通信系统的核心网设备接收到该PDN连接的上下文信息时，第二通信系统的核心网设备可以根据该PDN连接的上下文信息中包含的PDN网关的地址，将该PDN连接的上下文信息发送给该PDN网关(比如，4G和5G合设的核心网设备SMF+PGW-C)，从而建立与该PDN连接对应的PDU会话。其中，PDN网关的地址可以是IP地址，也可以是完全合格域名(Fully Qualified Domain Name，FQDN)，FQDN 也可以称为全称域名。第二通信系统的核心网设备向PDN网关发送的PDN连接的上下文信息可以是MME发送的PDN连接的上下文，或者是MME发送的PDN连接上下文的子集。例如，可以是PDN连接包含的承载的标识。
之后，当建立该PDN连接对应的PDU会话之后，第一通信系统的核心网设备可以向第一通信系统的基站发送切换命令，以使该基站向该UE发送切换命令(Handover Command)，当该UE接收到切换命令时，该UE可以从第一通信系统移动至第二通信系统。由于该UE是基于支持移动至第二通信系统的PDN连接从第一通信系统向第二通信系统移动，从而避免了在移动过程中因为PDN网关不可达，而造成移动过程中处理时延长的问题。
进一步的，在该UE从第一通信系统移动至第二通信系统之后，第一通信系统的核心网设备还可以发起删除流程，用于删除该UE上不支持移动至第二通信系统的PDN连接。
以图1所示的4G和5G通信系统为例，则第二通信系统的核心网设备可以为AMF，第一通信系统的核心网设备可以为MME，PDN网关可以为SMF+PGW-C，该UE可以通过图8所示的流程移动至第二通信系统。具体包括：S801.E-UTRAN向MME发送切换请求，该切换请求用于请求将该UE切换至5G；S802.MME确定目标系统为5G，即确定该UE需要移动至5G，则根据保存的该UE上的PDN连接支持网络互通的信息，仅向AMF发送支持移动至5G的PDN连接的上下文信息；S803.MME向AMF发送转发迁移请求(Forward Relocation Request)，该请求中包含该UE在4G网络内建立的PDN连接的信息，PDN连接信息中包含该PDN连接所使用的PDN网关(比如，SMF+PGW-C)的IP地址；S804.AMF获得PDN连接上下文中PDN网关的IP地址，并向该IP地址发送PDU会话切换请求，PDU会话切换请求包含PDN连接的上下文信息；S805.SMF+PGW-C向AMF发送PDU会话切换响应消息，该PDU会话切换响应消息中包含5G PDU会话的上下文信息；S806.AMF向5G RAN(即5G基站)发送切换请求(Handover Request)，该切换请求中包含PDU会话的信息；S807.5G RAN向AMF发送切换请求确认(ACK)；S808.AMF向SMF+PGW-C发送修改PDU会话请求；S809.SMF+PGW-C向AMF返回修改PDU会话响应；S810.AMF向MME发送转发迁移响应(Forward Relocation Response)；S811.MME向E-UTRAN发送切换命令(Handover Command)；S812.E-UTRAN向UE发送切换命令；S813.UE向5G RAN发送切换完成(Handover Complete)消息；S814.5G RAN向AMF发送切换通知(Handover Notify)；S815.AMF向MME发送转发迁移完成通知(Forward Relocation Complete Notification)；S816.MME发起删除不支持移动至5G的PDN连接的流程；S817.MME向AMF发送转发迁移完成通知确认(Forward Relocation Complete Notification ACK)。
本申请实施例提供的通信系统间移动方法中，第一通信系统的核心网设备在确定UE需要移动至第二通信系统时，向第二通信系统的核心网设备发送该UE上支持移动至第二通信系统的PDN连接的上下文信息，该PDN连接的上下文信息用于第二通信系统的核心网设备建立与该PDN连接对应的PDU会话，之后，第一通信系统的核心网设备向该UE发送切换命令，以使该UE从第一通信系统移动至第二通信系统。由 于该UE是基于支持移动至第二通信系统的PDN连接对应的PDU会话从第一通信系统向第二通信系统移动，从而避免了在移动过程中因为PDN网关不可达，而造成移动过程中处理时延长的问题。
图9为本申请实施例提供的一种通信系统间移动方法的流程图，参见图9，该方法包括以下几个步骤。
S901：第二通信系统的第一核心网设备获取UE在第一通信系统中的PDN连接对应的PDN网关的地址。
其中，该UE在第一通信系统中建立的PDN连接可以包括一个或者多个PDN连接，第一核心网设备可以获取每个PDN连接对应的PDN网关的地址。该PDN网关的地址可以是该PDN网关的IP地址，也可以是完全合格域名(Fully Qualified Domain Name，FQDN)，FQDN也可以称为全称域名。
具体的，第一核心网设备可以接收第一通信系统中的核心网设备发送的该UE在第一通信系统中建立的PDN连接的上下文信息，建立的PDN连接可以是一个或者多个PDN连接，该上下文信息中包含所有PDN连接对应的PDN网关的地址，从而第一核心网设备可以从该上下文信息中获取每个PDN连接对应的PDN网关的地址。
比如，第一通信系统可以为4G通信系统，第二通信系统可以为5G通信系统，第一核心网设备可以为AMF，PDN连接对应的PDN网关可以为4G和5G合设的核心网设备SMF+PGW-C，第一通信系统中的核心网设备为MME，图9中以MME、AMF和SMF+PGW-C为例说明。
S902：第一核心网设备向第二通信系统的第二核心网设备发送第一信息，第一信息包括PDN网关的地址。
其中，第二核心网设备用于为第一核心网设备判断该PDN网关的地址是否可达。比如，第二核心网设备可以为5G通信系统中的网络存储功能实体(Network Repository Function，NRF)，图9中以NRF为例说明。
具体的，第一核心网设备向第二通信系统的第二核心网设备发送第一信息之前，第一核心网设备可以自身先判断该PDN网关的地址是否可达，当第一核心网设备确定该PDN网关的地址不可达时，则第一核心网设备可以第二核心网设备发送包含该PDN网关的地址的第一信息。第一核心网设备确定该PDN网关的地址不可达可以包括：该第一核心网设备根据保存的信息确定该PDN网关的地址不可达，或者，该第一核心网设备无法确定该PDN网关的地址是否可达。
进一步的，第一核心网设备还可以根据该PDN网关的地址，判断该UE是否处于漫游状态，当确定该UE处于漫游状态时，则第一核心网设备可以在自身判断该PDN网关的地址不可达时，向第二核心网设备发送的第一信息还可以包括数据网络名称DNN和公共陆地移动网络(Public Land Mobile Network，PLMN)标识。即第一核心网设备在确定该UE处于漫游状态，且该PDN网关的地址不可达时，向第二核心网设备发送的第一信息中包括以下信息：该PDN网关的地址、DNN和PLMN标识。
S903：当第二核心网设备接收到第一信息时，第二核心网设备向第一核心网设备发送第二信息，第二信息用于指示该PDN网关的地址是否可达。
其中，当第二核心网设备接收到第一信息时，第二核心网设备可以判断该PDN网 关的地址是否可达，并将判断结果通过第二信息发送给第一核心网设备，即第二信息用于指示该PDN网关的地址是否可达。当第二核心网设备确定该PDN网关的地址可达时，则执行S904；否则，该UE无法从第一通信系统移动至第二通信系统，流程结束。
可选的，当第二核心网设备确定该PDN网关的地址可达时，则第二信息可以包括第一指示信息，第一指示信息用于指示该PDN网关的地址可达；当第二核心网设备确定该PDN网关的地址不可达时，则第二信息可以包括第二指示信息，第二指示信息用于指示该PDN网关的地址不可达。
进一步的，当第二核心网设备确定该PDN网关的地址可达，且该UE处于漫游状态时，第二核心网设备发送给第一核心网设备的第二信息还可以包括v-SMF的地址，v-SMF为该UE处于漫游时的会话管理网元。
S904：当第一核心网设备确定该PDN网关的地址可达时，则第一核心网设备向该PDN网关发送该PDN连接的上下文信息，该PDN连接的上下文信息用于该PDN网关在第二通信系统内建立与该PDN连接对应的PDU会话。
S905：该PDN网关接收该PDN连接的上下文信息，并根据该PDN连接的上下文信息建立与该PDN连接对应的PDU会话，以使该UE从第一通信系统与移动至第二通信信息。
当第一核心网设备接收到第二信息，并根据第二信息确定该PDN网关的地址可达时，第一核心网设备可以向该PDN网关发送该PDN连接的上下文信息，当该PDN网关接收到该上下文信息后，可以基于该上下文信息建立与该PDN连接对应的PDU会话。当建立与该PDN连接对应的PDU会话后，该UE可以从第一通信系统移动至第二通信系统。
进一步的，在第一核心网设备向该PDN网关发送该PDN连接的上下文信息，该PDN网关根据该PDN连接的上下文信息建立与该PDN连接对应的PDU会话之后，该PDN网关可以向第一核心网设备发送PDN连接包括的EPS承载的标识集。相应的，第一核心网设备接收该PDN连接包括的EPS承载的标识集(EBIs)，根据该EPS承载的标识集，生成EPS承载建立信息，并向第一通信系统的核心网设备发送EPS承载建立信息，EPS承载建立信息用于第一通信系统的核心网设备确定该UE成功切换的EPS承载。其中，EPS承载建立信息可以为EPS承载建立列表(EPS Bearer Setup List)，当第一通信系统的核心网设备接收到该EPS承载建立列表时，可以确定该UE成功切换的EPS承载。
示例性的，当该UE处于连接态(Connected)时，以图1所示的4G和5G通信系统为例，则第一核心网设备可以为AMF，第二核心网设备可以为NRF，PDN网关可以为SMF+PGW-C，结合图9所示的方法，该UE从第一通信系统移动至第二通信系统的流程可以如图10所示。具体包括：S1001.E-UTRAN向MME发送切换请求，该切换请求用于请求将该UE切换至5G；S1002.MME向AMF发送转发迁移请求(Forward Relocation Request)，该请求中包含该UE在4G网络内建立的PDN连接的信息，PDN连接信息中包含该PDN连接所使用的PDN网关(比如，SMF+PGW-C)的IP地址；S1003.AMF获得PDN连接上下文中PDN网关的IP地址，判断该IP地址 是否可达，以及UE是否处于漫游状态(当不可达时则执行S1004，当可达时则执行S1006)；S1004.AMF向NRF发送NF发现请求(当S1003中确定不可达且该UE处于漫游状态时则携带DNN和PLMN)；S1005.NRF向AMF返回NF发现响应(当该UE处于漫游状态时则携带v-SMF地址)；S1006.AMF获得PDN连接上下文中PDN网关的IP地址，并向该IP地址发送PDU会话切换请求，PDU会话切换请求包含PDN连接的上下文信息；S1007.SMF+PGW-C向AMF发送PDU会话切换响应消息，该PDU会话切换响应消息中包含5G PDU会话的上下文信息；S1008.AMF向5G RAN(即5G基站)发送切换请求，该切换请求中包含PDU会话的信息；S1009.5G RAN向AMF发送切换请求确认；S1010.AMF向SMF+PGW-C发送修改PDU会话请求；S1011.SMF+PGW-C判断出该UE需要从4G移动至5G，则向AMF返回修改PDU会话响应，该响应中携带PDU会话对应的PDN连接的EPS承载的标识集(EBIs)；S1012.AMF收集所有SMF+PGW-C返回的消息后，生成EPS承载建立列表；S1013.AMF向MME发送包含EPS承载建立列表的转发迁移响应；S1014.MME向E-UTRAN发送切换命令；S1015.E-UTRAN向UE发送切换命令；S1016.UE向5G RAN发送切换完成消息；S1017.5G RAN向AMF发送切换通知；S1018.AMF向MME发送转发迁移完成通知；S1019.MME向AMF发送转发迁移完成通知确认。
示例性的，当该UE处于空闲态(Idle)时，以图1所示的4G和5G通信系统为例，则第一核心网设备可以为AMF，第二核心网设备可以为NRF，PDN网关可以为SMF+PGW-C，结合图9所示的方法，该UE从第一通信系统移动至第二通信系统的流程可以如图11所示。具体包括：S1101.该UE确定需要从4G移动至5G，获取支持移动至5G的PDN连接对应的PDU会话的会话标识列表，并使用会话标识列表生成第一PDU会话状态信息；S1102.该UE向AMF发送注册请求，该注册请求中包括第一PDU会话状态信息；S1103.AMF向MME发送上下文请求，该上下文请求用于获取该UE上所有PDN连接的上下文信息；S1104.MME向AMF返回包含该上下文信息的上下文响应；S1105.AMF向MME发送上下文确认；S1106.AMF向UDM+HSS发送更新位置请求；S1107.UDM+HSS向AMF返回更新位置响应；S1108.UDM+HSS向MME发送取消位置；S1109.MME向UDM+HSS返回取消位置确认；S1110.AMF获取PDN连接的上下文信息中PDN网关从IP地址，判断该IP地址是否可达以及该UE是否处于漫游状态(当不可达时则执行步骤S1111，当可达时则执行步骤S1113)；S1111.AMF向NRF发送NF发现请求(当步骤S1110中确定不可达且该UE处于漫游状态时则携带DNN和PLMN)；S1112.NRF向AMF返回NF发现响应(当该UE处于漫游状态时则携带v-SMF地址)；S1113.AMF向SMF+PGW-C发送N11消息，N11消息中携带支持移动至5G的PDN连接对应的PDU会话的标识(ID(s))；S1114.SMF+PGW-C向AMF返回N11响应；S1115.AMF向该UE发送注册接受消息，该注册接受消息中包含第二PDU会话状态信息；S1116.该UE向AMF返回注册完成消息；S1117.该UE可以根据第二PDU会话状态信息获得对应的PDN连接的标识(ID)，并删除获取的PDN连接的ID以外的其他PDN连接的上下文信息。
需要说明的是，上述实施例中的第一PDU会话状态信息、第二PDU会话状态信息和支持移动至5G的PDN连接，与图5所在的实施例中的解释一致，具体参见图5 所在的实施例中的描述，本申请实施例在此不再赘述。
本申请实施例提供的通信系统间移动方法中，第一核心网设备在获取该UE在第一通信系统中的PDN连接对应的PDN网关的地址后，只有在确定该PDN网关的地址可达时，才向该PDN网关发送PDN连接的上下文信息，以使该PDN网关在第二通信系统内建立与该PDN连接对应的PDU会话，以使该UE从第一通信系统移动至第二通信系统，从而避免了在移动过程中因为PDN网关不可达，而造成移动过程中处理时延长的问题。
上述主要从各个网元之间交互的角度对本申请实施例提供的方案进行了介绍。可以理解的是，各个网元，例如用户设备、第一通信系统的核心网设备和第二通信系统的核心网设备等为了实现上述功能，其包含了执行各个功能相应的硬件结构和/或软件模块。本领域技术人员应该很容易意识到，结合本文中所公开的实施例描述的各示例的网元及算法步骤，本申请能够以硬件或硬件和计算机软件的结合形式来实现。某个功能究竟以硬件还是计算机软件驱动硬件的方式来执行，取决于技术方案的特定应用和设计约束条件。专业技术人员可以对每个特定的应用来使用不同方法来实现所描述的功能，但是这种实现不应认为超出本申请的范围。
本申请实施例可以根据上述方法示例对用户设备、第一通信系统的核心网设备和第二通信系统的核心网设备进行功能模块的划分，例如，可以对应各个功能划分各个功能模块，也可以将两个或两个以上的功能集成在一个处理模块中。上述集成的模块既可以采用硬件的形式实现，也可以采用软件功能模块的形式实现。需要说明的是，本申请实施例中对模块的划分是示意性的，仅仅为一种逻辑功能划分，实际实现时可以有另外的划分方式。
在采用对应各个功能划分各个功能模块的情况下，图12示出了上述实施例中所涉及的用户设备的一种可能的结构示意图，用户设备包括：处理单元1201、发送单元1202和接收单元1203。其中，处理单元1201、发送单元1202和接收单元1203用于支持用户设备执行图3中的S301；处理单元1201还用于支持用户设备执行图3中的S302；发送单元1202还用于支持用户设备执行图3中的S303；接收单元1203还用于支持用户设备执行图3中的S304。上述方法实施例涉及的各步骤的所有相关内容均可以援引到对应功能模块的功能描述，在此不再赘述。
在硬件实现上，上述处理单元1201可以为处理器；发送单元1202可以为发送器，接收单元1203可以为接收器，发送器与接收器可以构成通信接口。
图13所示，为本申请的实施例提供的上述实施例中所涉及的用户设备的一种可能的逻辑结构示意图。用户设备包括：处理器1302、通信接口1303、存储器1301以及总线1304。处理器1302、通信接口1303以及存储器1301通过总线1304相互连接。在本申请的实施例中，处理器1302用于对用户设备的动作进行控制管理，例如，处理器1302用于支持用户设备执行图3中的S301和S302，和/或用于本文所描述的技术的其他过程。通信接口1303用于支持用户设备进行通信。存储器1301，用于存储用户设备的程序代码和数据。
其中，处理器1302可以是中央处理器单元，通用处理器，数字信号处理器，专用集成电路，现场可编程门阵列或者其他可编程逻辑器件、晶体管逻辑器件、硬 件部件或者其任意组合。其可以实现或执行结合本申请公开内容所描述的各种示例性的逻辑方框，模块和电路。所述处理器也可以是实现计算功能的组合，例如包含一个或多个微处理器组合，数字信号处理器和微处理器的组合等等。总线1304可以是外设部件互连标准(Peripheral Component Interconnect，PCI)总线或扩展工业标准结构(Extended Industry Standard Architecture，EISA)总线等。所述总线可以分为地址总线、数据总线、控制总线等。为便于表示，图13中仅用一条粗线表示，但并不表示仅有一根总线或一种类型的总线。
在采用对应各个功能划分各个功能模块的情况下，图14示出了上述实施例中所涉及的第一通信系统的核心网设备的一种可能的结构示意图，比如，该核心网设备可以为4G网络中的MME。第一通信系统的核心网设备包括：处理单元1401、发送单元1402和接收单元1403。其中，处理单元1401用于支持该核心网设备执行图7中的S701；发送单元1402用于支持该核心网设备执行图7中的S702；处理单元1401、发送单元1402和接收单元1403用于支持该核心网设备执行图7中的S703，和/或用于本文所描述的技术的其他过程。上述方法实施例涉及的各步骤的所有相关内容均可以援引到对应功能模块的功能描述，在此不再赘述。
在硬件实现上，上述处理单元1401可以为处理器，发送单元1402可以为发送器，接收单元1403可以为接收器，接收器与发送器可以构成通信接口。
图15所示，为本申请的实施例提供的上述实施例中所涉及的第一通信系统的核心网设备的一种可能的逻辑结构示意图，比如，该核心网设备可以为4G网络中的MME。第一通信系统的核心网设备包括：处理器1502、通信接口1503、存储器1501以及总线1504。处理器1502、通信接口1503以及存储器1501通过总线1504相互连接。在申请的实施例中，处理器1502用于对该核心网设备的动作进行控制管理，例如，处理器1502用于支持该核心网设备执行图7中的S701，和/或用于本文所描述的技术的其他过程。通信接口1503用于支持该核心网设备进行通信。存储器1501，用于存储该核心网设备的程序代码和数据。
其中，处理器1502可以是中央处理器单元，通用处理器，数字信号处理器，专用集成电路，现场可编程门阵列或者其他可编程逻辑器件、晶体管逻辑器件、硬件部件或者其任意组合。其可以实现或执行结合本申请公开内容所描述的各种示例性的逻辑方框，模块和电路。所述处理器也可以是实现计算功能的组合，例如包含一个或多个微处理器组合，数字信号处理器和微处理器的组合等等。总线1504可以是外设部件互连标准PCI总线或扩展工业标准结构EISA总线等。所述总线可以分为地址总线、数据总线、控制总线等。为便于表示，图15中仅用一条粗线表示，但并不表示仅有一根总线或一种类型的总线。
在采用对应各个功能划分各个功能模块的情况下，图16示出了上述实施例中所涉及的第二通信系统的核心网设备的一种可能的结构示意图，比如，该核心网设备可以为5G网络中的AMF。第二通信系统的核心网设备包括：获取单元1601、发送单元1602和处理单元1603。其中，获取单元1601用于支持该核心网设备执行图9中的S901、以及支持该核心网设备接收图9中的S903发送的第二信息；发送单元1602用于支持该核心网设备执行图9中的S902和S904；获取单元1601、发送单元 1602和处理单元1603用于支持该核心网设备执行图9中的S905，和/或用于本文所描述的技术的其他过程。上述方法实施例涉及的各步骤的所有相关内容均可以援引到对应功能模块的功能描述，在此不再赘述。
在硬件实现上，上述处理单元1603可以为处理器；获取单元1601可以为接收器，发送单元1603可以为发送器，接收器与接收器可以构成通信接口。
图17所示，为本申请的实施例提供的上述实施例中所涉及的第二通信系统的核心网设备的一种可能的逻辑结构示意图，比如，该核心网设备可以为5G网络中的AMF。第二通信系统的核心网设备包括：处理器1702、通信接口1703、存储器1701以及总线1704。处理器1702、通信接口1703以及存储器1701通过总线1704相互连接。在申请的实施例中，处理器1702用于对该核心网设备的动作进行控制管理，例如，处理器1702用于支持该核心网设备执行图9中的S905，和/或用于本文所描述的技术的其他过程。通信接口1703用于支持该核心网设备进行通信。存储器1701，用于存储该核心网设备的程序代码和数据。
其中，处理器1702可以是中央处理器单元，通用处理器，数字信号处理器，专用集成电路，现场可编程门阵列或者其他可编程逻辑器件、晶体管逻辑器件、硬件部件或者其任意组合。其可以实现或执行结合本申请公开内容所描述的各种示例性的逻辑方框，模块和电路。所述处理器也可以是实现计算功能的组合，例如包含一个或多个微处理器组合，数字信号处理器和微处理器的组合等等。总线1704可以是外设部件互连标准PCI总线或扩展工业标准结构EISA总线等。所述总线可以分为地址总线、数据总线、控制总线等。为便于表示，图17中仅用一条粗线表示，但并不表示仅有一根总线或一种类型的总线。
在本申请的另一实施例中，还提供一种可读存储介质中，可读存储介质中包括若干指令用以使得一个设备(可以是单片机，芯片等)或处理器执行本发明各个实施例所述方法的全部或部分步骤，具体可以执行图3-图11任一图示所提供的通信系统间移动方法中任一设备的步骤。而前述的可读存储介质包括：U盘、移动硬盘、只读存储器(Read-Only Memory，ROM)、随机存取存储器(Random Access Memory，RAM)、磁碟或者光盘等各种可以存储程序代码的介质。
在本申请的另一方面还提供一种计算机程序产品，该计算机程序产品包括计算机执行指令，该计算机执行指令存储在计算机可读存储介质中；设备的至少一个处理器可以从计算机可读存储介质读取该计算机执行指令，至少一个处理器执行该计算机执行指令使得设备执行本发明各个实施例所述方法的全部或部分步骤，具体可以执行图3-图11任一图示所提供的通信系统间移动方法中任一设备的步骤。
在本申请的另一实施例中，还提供一种系统，该系统包括用户设备、第一通信系统的核心网设备和第二通信系统的核心网设备；其中，用户设备为上述图2、图12或图13所提供的用户设备；和/或，第一通信系统的核心网设备为上述图14或图15所提供的核心网设备；和/或，第二通信系统的核心网设备为上述图16或图17所提供的核心网设备。
在本申请实施例提供的系统中，该UE可以基于支持移动至第二通信系统的PDN连接对应的PDU会话从第一通信系统移动至第二通信系统，或者在确定该UE的PDN 连接对应的PDN网关的地址可达后从第一通信系统移动至第二通信系统，从而避免了该UE在移动过程中因为PDN网关不可达，而造成移动过程中处理时延长的问题。
以上所述，仅为本发明的具体实施方式，但本发明的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本发明揭露的技术范围内，可轻易想到变化或替换，都应涵盖在本发明的保护范围之内。因此，本发明的保护范围应以所述权利要求的保护范围为准。

Claims (53)

  1. 一种通信系统间移动方法，其特征在于，所述方法包括：
    用户设备UE在第一通信系统内建立至少一个PDN连接；
    所述UE生成第一PDU会话状态信息，所述第一PDU会话状态信息用于指示所述至少一个PDN连接中支持移动至第二通信系统的PDN连接所对应的PDU会话；
    所述UE向所述第二通信系统的核心网设备发送注册消息，所述注册消息中包含所述第一PDU会话状态信息；
    所述UE接收所述第二通信系统的核心网设备发送的注册接受消息。
  2. 根据权利要求1所述的方法，其特征在于，所述UE在第一通信系统内建立至少一个PDN连接，包括：
    所述UE向第一通信系统的核心网设备发送第一消息，所述第一消息用于所述UE在所述第一通信系统内建立PDN连接；
    所述UE接收第一信息，所述第一信息用于所述UE确定所述PDN连接支持或不支持移动至所述第二通信系统。
  3. 根据权利要求1或2所述的方法，其特征在于，所述UE生成第一PDU会话状态信息，包括：
    所述UE使用支持移动至第二通信系统的PDN连接相对应的PDU会话的标识生成所述第一PDU会话状态信息。
  4. 根据权利要求3所述的方法，其特征在于，所述UE使用支持移动至第二通信系统的PDN连接相对应的PDU会话的标识生成所述第一PDU会话状态信息，包括：
    所述UE根据所述支持移动至第二通信系统的PDN连接的标识获得所述PDU会话的标识。
  5. 根据权利要求4所述的方法，其特征在于，所述UE根据所述支持移动至第二通信系统的PDN连接的标识获得所述PDU会话的标识，包括：
    所述UE将所述支持移动至第二通信系统的PDN连接的标识设置为所述PDU会话的标识。
  6. 根据权利要求2-5任一项所述的方法，其特征在于，
    所述第一信息包括第一指示信息，所述第一指示信息用于指示所述UE的PDN连接支持移动至所述第二通信系统，所述方法还包括：所述UE根据所述第一指示信息确定所述PDN连接支持移动至所述第二通信系统；或者，
    所述第一信息包括第二指示信息，所述第二指示信息用于指示所述UE的PDN连接不支持移动至所述第二通信系统，所述方法还包括：所述UE根据所述第二指示信息确定所述PDN连接不支持移动至所述第二通信系统。
  7. 根据权利要求2-6任一项所述的方法，其特征在于，所述第一信息包括所述PDN连接对应的PDU会话的会话信息，所述会话信息包括以下信息中的至少一项：会话AMBR、QoS规则、SSC模式或PDU会话标识，所述方法还包括：
    所述UE根据所述会话信息，确定所述PDN连接支持移动至所述第二通信系统。
  8. 根据权利要求2-7任一项所述的方法，其特征在于，所述第一信息包含在协议配置选项PCO中。
  9. 根据权利要求1-8任一项所述的方法，其特征在于，所述UE生成第一PDU会话状态信息之前，所述方法还包括：
    所述UE确定需要从所述第一通信系统移动至所述第二通信系统。
  10. 根据权利要求1-9任一项所述的方法，其特征在于，所述注册接受消息中包含第二PDU会话状态信息，所述第二PDU会话状态信息用于指示所述UE在所述第二通信系统中使用的PDU会话，所述方法还包括：
    所述UE删除与所述第二PDU会话状态信息所指示的PDU会话相对应的PDN连接之外的其他PDN连接。
  11. 根据权利要求1-10任一项所述的方法，其特征在于，所述第一通信系统为第四代4G通信系统，所述第二通信系统为第五代5G通信系统。
  12. 一种通信系统间移动方法，其特征在于，所述方法包括：
    第一通信系统的核心网设备确定用户设备UE需要移动至第二通信系统；
    所述第一通信系统的核心网设备向所述第二通信系统的核心网设备发送所述UE上支持移动至所述第二通信系统的PDN连接的上下文信息，所述PDN连接的上下文信息用于所述第二通信系统的核心网设备建立与所述PDN连接对应的PDU会话，以实现所述UE从所述第一通信系统移动至所述第二通信系统。
  13. 根据权利要求12所述的方法，其特征在于，所述第一通信系统的核心网设备向所述第二通信系统的核心网设备发送所述UE上支持移动至所述第二通信系统的PDN连接的上下文信息之前，所述方法还包括：
    所述第一通信系统的核心网设备确定所述PDN连接支持或不支持移动至所述第二通信系统。
  14. 根据权利要求12或13所述的方法，其特征在于，所述第一通信系统的核心网设备确定用户设备UE需要移动至第二通信系统，包括：
    所述第一通信系统的核心网设备接收基站发送的切换请求；
    所述第一通信系统的核心网设备根据所述切换请求，确定所述UE需要移动至第二通信系统。
  15. 根据权利要求12-14任一项所述的方法，其特征在于，所述方法还包括：
    所述第一通信系统的核心网设备删除所述UE上不支持移动至所述第二通信系统的PDN连接。
  16. 根据权利要求12或13所述的方法，其特征在于，所述第一通信系统的核心网设备确定用户设备UE需要移动至第二通信系统，包括：
    所述第一通信系统的核心网设备接收上下文请求消息；
    所述第一通信系统的核心网设备根据所述上下文请求消息的发送方属于所述第二通信系统，确定所述UE需要移动至所述第二通信系统。
  17. 根据权利要求16所述的方法，其特征在于，
    所述上下文请求消息包含第二信息，所述第二信息用于指示所述上下文请求消息的发送方属于所述第二通信系统；或者，
    所述上下文请求消息包含所述UE的GUTI，所述方法还包括：所述第一通信系统的核心网设备根据所述UE的GUTI是从所述第二通信系统的GUTI映射的，确定所述 上下文请求消息的发送方属于所述第二通信系统。
  18. 根据权利要求17所述的方法，其特征在于，所述方法还包括：
    所述第一通信系统的核心网设备确定所述UE上不支持移动至所述第二通信系统中的PDN连接，所述第一通信系统的核心网设备发送会话删除请求，所述会话删除请求包含操作指示标志。
  19. 一种系统间移动方法，其特征在于，所述方法包括：
    第二通信系统的第一核心网设备获取用户设备UE在第一通信系统中的PDN连接对应的PDN网关的地址；
    所述第一核心网设备向所述第二通信系统的第二核心网设备发送第一信息，所述第一信息包括所述PDN网关的地址；
    所述第一核心网设备接收所述第二核心网设备发送的第二信息，所述第二信息用于指示所述PDN网关的地址可达或不可达；
    当所述PDN网关的地址可达时，则所述第一核心网设备向所述PDN网关发送所述PDN连接的上下文信息，所述PDN连接的上下文信息用于所述PDN网关在所述第二通信系统内建立与所述PDN连接对应的PDU会话，以实现所述UE从所述第一通信系统移动至所述第二通信系统。
  20. 根据权利要求19所述的方法，其特征在于，所述第一核心网设备获取UE在第一通信系统中的PDN连接对应的PDN网关的地址，包括：
    所述第一核心网设备接收所述UE在第一通信系统中的所述PDN连接的上下文信息；
    所述第一核心网设备根据所述上下文信息，获取所述PDN连接对应的PDN网关的地址。
  21. 根据权利要求19或20所述的方法，其特征在于，所述第一核心网设备向所述第二通信系统的第二核心网设备发送第一信息之前，所述方法还包括：
    所述第一核心网设备判断所述PDN网关的地址是否可达；
    所述第一核心网设备向所述第二通信系统的第二核心网设备发送第一信息，包括：
    当所述PDN网关的地址不可达时，所述第一核心网设备向所述第二核心网设备发送第一信息。
  22. 根据权利要求19-21任一项所述的方法，其特征在于，所述方法还包括：
    所述第一核心网设备根据所述PDN网关的地址，判断所述UE是否处于漫游状态；
    当所述UE处于漫游状态时，所述第一信息还包括数据网络名称(DNN)和公共陆地移动网络(PLMN)标识。
  23. 根据权利要求22所述的方法，其特征在于，所述第二信息还包括v-SMF的地址，所述v-SMF为所述UE处于漫游时的会话管理网元。
  24. 根据权利要求19-23任一项所述的方法，其特征在于，所述第一核心网设备向所述PDN网关发送所述PDN连接的上下文信息之后，所述方法还包括：
    所述第一核心网设备接收所述PDN网关发送的PDN连接包括的EPS承载的标识集；
    所述第一核心网设备根据所述EPS承载的标识集，生成EPS承载建立信息，并向 所述第一通信系统的核心网设备发送所述EPS承载建立信息，所述EPS承载建立信息用于所述第一通信系统的核心网设备确定所述UE成功切换的EPS承载。
  25. 一种用户设备，其特征在于，所述用户设备包括：
    处理单元，用于在第一通信系统内建立至少一个PDN连接；
    所述处理单元，还用于生成第一PDU会话状态信息，所述第一PDU会话状态信息用于指示所述至少一个PDN连接中支持移动至第二通信系统的PDN连接所对应的PDU会话；
    发送单元，用于向所述第二通信系统的核心网设备发送注册消息，所述注册消息中包含所述第一PDU会话状态信息；
    接收单元，用于接收所述第二通信系统的核心网设备发送的注册接受消息。
  26. 一种核心网设备，其特征在于，所述核心网设备为第一通信系统的核心网设备，包括：
    处理单元，用于确定用户设备UE需要移动至第二通信系统；
    发送单元，用于向所述第二通信系统的核心网设备发送所述UE上支持移动至所述第二通信系统的PDN连接的上下文信息，所述PDN连接的上下文信息用于所述第二通信系统的核心网设备建立与所述PDN连接对应的PDU会话，以实现所述UE从所述第一通信系统移动至所述第二通信系统。
  27. 一种核心网设备，其特征在于，所述核心网设备为第二通信系统的第一核心网设备，包括：
    获取单元，用于获取用户设备UE在第一通信系统中的PDN连接对应的PDN网关的地址；
    发送单元，用于向所述第二通信系统的第二核心网设备发送第一信息，所述第一信息包括所述PDN网关的地址；
    所述获取单元，还用于接收所述第二核心网设备发送的第二信息，所述第二信息用于指示所述PDN网关的地址可达或不可达；
    所述发送单元，还用于当所述PDN网关的地址可达时，向所述PDN网关发送所述PDN连接的上下文信息，所述PDN连接的上下文信息用于所述PDN网关在所述第二通信系统内建立与所述PDN连接对应的PDU会话，以实现所述UE从所述第一通信系统移动至所述第二通信系统。
  28. 一种用户设备，其特征在于，所述用户设备包括存储器、处理器、通信接口和总线，所述存储器中存储代码和数据，所述处理器、所述存储器和所述通信接口通过所述总线连接；其中，
    所述处理器，用于在第一通信系统内建立至少一个PDN连接；
    所述处理器，还用于生成第一PDU会话状态信息，所述第一PDU会话状态信息用于指示所述至少一个PDN连接中支持移动至第二通信系统的PDN连接所对应的PDU会话；
    所述通信接口，用于通过向所述第二通信系统的核心网设备发送注册消息，所述注册消息中包含所述第一PDU会话状态信息；
    所述通信接口，还用于接收所述第二通信系统的核心网设备发送的注册接受消 息。
  29. 根据权利要求28所述的用户设备，其特征在于，
    所述通信接口，还用于向第一通信系统的核心网设备发送第一消息，所述第一消息用于所述UE在所述第一通信系统内建立PDN连接；
    所述通信接口，还用于接收第一信息，所述第一信息用于所述UE确定所述PDN连接支持或不支持移动至所述第二通信系统。
  30. 根据权利要求28或29所述的用户设备，其特征在于，所述处理器，还用于：
    使用支持移动至第二通信系统的PDN连接相对应的PDU会话的标识生成所述第一PDU会话状态信息。
  31. 根据权利要求30所述的用户设备，其特征在于，所述处理器，还用于：
    根据所述支持移动至第二通信系统的PDN连接的标识获得所述PDU会话的标识。
  32. 根据权利要求31所述的用户设备，其特征在于，所述处理器，具体用于：
    将所述支持移动至第二通信系统的PDN连接的标识设置为所述PDU会话的标识。
  33. 根据权利要求29-32任一项所述的用户设备，其特征在于，
    所述第一信息包括第一指示信息，所述第一指示信息用于指示所述UE的PDN连接支持移动至所述第二通信系统，所述处理器，还用于根据所述第一指示信息确定所述PDN连接支持移动至所述第二通信系统；或者，
    所述第一信息包括第二指示信息，所述第二指示信息用于指示所述UE的PDN连接不支持移动至所述第二通信系统，所述处理器，还用于根据所述第二指示信息确定所述PDN连接不支持移动至所述第二通信系统。
  34. 根据权利要求29-33任一项所述的用户设备，其特征在于，所述第一信息包括所述PDN连接对应的PDU会话的会话信息，所述会话信息包括以下信息中的至少一项：会话AMBR、QoS规则、SSC模式或PDU会话标识，所述处理器，还用于：
    根据所述会话信息，确定所述PDN连接支持移动至所述第二通信系统。
  35. 根据权利要求29-34任一项所述的用户设备，其特征在于，所述第一信息包含在协议配置选项PCO中。
  36. 根据权利要求28-35任一项所述的用户设备，其特征在于，所述处理器，还用于：
    确定需要从所述第一通信系统移动至所述第二通信系统。
  37. 根据权利要求28-36任一项所述的用户设备，其特征在于，所述注册接受消息中包含第二PDU会话状态信息，所述第二PDU会话状态信息用于指示所述UE在所述第二通信系统中使用的PDU会话，所述处理器，还用于：
    删除与所述第二PDU会话状态信息所指示的PDU会话相对应的PDN连接之外的其他PDN连接。
  38. 根据权利要求28-37任一项所述的用户设备，其特征在于，所述第一通信系统为第四代4G通信系统，所述第二通信系统为第五代5G通信系统。
  39. 一种核心网设备，其特征在于，所述核心网设备为第一通信系统的核心网设备，包括存储器、处理器、通信接口和总线，所述存储器中存储代码和数据，所述处理器、所述存储器和所述通信接口通过所述总线连接；其中，
    所述处理器，用于确定用户设备UE需要移动至第二通信系统；
    所述通信接口，用于向所述第二通信系统的核心网设备发送所述UE上支持移动至所述第二通信系统的PDN连接的上下文信息，所述PDN连接的上下文信息用于所述第二通信系统的核心网设备建立与所述PDN连接对应的PDU会话，以实现所述UE从所述第一通信系统移动至所述第二通信系统。
  40. 根据权利要求39所述的核心网设备，其特征在于，所述处理器，还用于：
    确定所述PDN连接支持或不支持移动至所述第二通信系统。
  41. 根据权利要求39或40所述的核心网设备，其特征在于，
    所述通信接口，还用于接收基站发送的切换请求；
    所述处理器，还用于根据所述切换请求，确定所述UE需要移动至第二通信系统。
  42. 根据权利要求39-41任一项所述的核心网设备，其特征在于，所述处理器，还用于：
    删除所述UE上不支持移动至所述第二通信系统的PDN连接。
  43. 根据权利要求39或40所述的核心网设备，其特征在于，
    所述通信接口，还用于接收上下文请求消息；
    所述处理器，还用于根据所述上下文请求消息的发送方属于所述第二通信系统，确定所述UE需要移动至所述第二通信系统。
  44. 根据权利要求43所述的核心网设备，其特征在于，
    所述上下文请求消息包含第二信息，所述第二信息用于指示所述上下文请求消息的发送方属于所述第二通信系统；或者，
    所述上下文请求消息包含所述UE的GUTI，所述处理器还用于根据所述UE的GUTI是从所述第二通信系统的GUTI映射的，确定所述上下文请求消息的发送方属于所述第二通信系统。
  45. 根据权利要求44所述的核心网设备，其特征在于，所述处理器，还用于：
    确定所述UE上不支持移动至所述第二通信系统中的PDN连接，所述第一通信系统的核心网设备发送会话删除请求，所述会话删除请求包含操作指示标志。
  46. 一种核心网设备，其特征在于，所述核心网设备为第二通信系统的第一核心网设备，包括存储器、处理器、通信接口和总线，所述存储器中存储代码和数据，所述处理器、所述存储器和所述通信接口通过所述总线连接；其中，
    所述处理器，用于获取用户设备UE在第一通信系统中的PDN连接对应的PDN网关的地址；
    所述通信接口，用于向所述第二通信系统的第二核心网设备发送第一信息，所述第一信息包括所述PDN网关的地址；
    所述通信接口，还用于接收所述第二核心网设备发送的第二信息，所述第二信息用于指示所述PDN网关的地址可达或不可达；
    所述通信接口，还用于当所述PDN网关的地址可达时，向所述PDN网关发送所 述PDN连接的上下文信息，所述PDN连接的上下文信息用于所述PDN网关在所述第二通信系统内建立与所述PDN连接对应的PDU会话，以实现所述UE从所述第一通信系统移动至所述第二通信系统。
  47. 根据权利要求46所述的核心网设备，其特征在于，
    所述通信接口，还用于接收所述UE在第一通信系统中的所述PDN连接的上下文信息；
    所述处理器，还用于根据所述上下文信息，获取所述PDN连接对应的PDN网关的地址。
  48. 根据权利要求46或47所述的核心网设备，其特征在于，
    所述处理器，还用于判断所述PDN网关的地址是否可达；
    所述通信接口，还用于当所述PDN网关的地址不可达时，所述第一核心网设备向所述第二核心网设备发送第一信息。
  49. 根据权利要求46-48任一项所述的核心网设备，其特征在于，所述处理器，还用于：
    根据所述PDN网关的地址，判断所述UE是否处于漫游状态；
    当所述UE处于漫游状态时，所述第一信息还包括数据网络名称(DNN)和公共陆地移动网络(PLMN)标识。
  50. 根据权利要求49所述的核心网设备，其特征在于，所述第二信息还包括v-SMF的地址，所述v-SMF为所述UE处于漫游时的会话管理网元。
  51. 根据权利要求46-50任一项所述的核心网设备，其特征在于，
    所述通信接口，还用于接收所述PDN网关发送的PDN连接包括的EPS承载的标识集；
    所述处理器，还用于根据所述EPS承载的标识集，生成EPS承载建立信息；
    所述通信接口，还用于向所述第一通信系统的核心网设备发送所述EPS承载建立信息，所述EPS承载建立信息用于所述第一通信系统的核心网设备确定所述UE成功切换的EPS承载。
  52. 一种可读存储介质，其特征在于，所述可读存储介质中存储有指令，当所述可读存储介质在设备上运行时，使得所述设备执行上述权利要求1-11任一项所述的通信系统间移动方法、或者执行上述权利要求12-18任一项所述的通信系统间移动方法、或者执行上述权利要求19-24任一项所述的通信系统间移动方法。
  53. 一种计算机程序产品，其特征在于，当所述计算机程序产品在计算机上运行时，使得所述计算机执行上述权利要求1-11任一项所述的通信系统间移动方法、或者执行上述权利要求12-18任一项所述的通信系统间移动方法、或者执行上述权利要求19-24任一项所述的通信系统间移动方法。
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