CN111356162A

CN111356162A - Session switching method and device

Info

Publication number: CN111356162A
Application number: CN201811565580.3A
Authority: CN
Inventors: 王胡成
Original assignee: China Academy of Telecommunications Technology CATT
Current assignee: Datang Mobile Communications Equipment Co Ltd
Priority date: 2018-12-20
Filing date: 2018-12-20
Publication date: 2020-06-30
Anticipated expiration: 2038-12-20
Also published as: CN111356162B

Abstract

The application discloses a session switching method and device, which are used for avoiding switching a PDU session which does not support roaming to a target PLMN when the PDU session is switched across PLMNs. The session switching method provided by the embodiment of the application comprises the following steps: judging whether the protocol data unit PDU session can be switched across public land mobile network PLMN or not; and switching the PDU session capable of switching to the target PLMN, or informing the next generation access network NG RAN of the PDU session capable of switching across PLMNs.

Description

Session switching method and device

Technical Field

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

Background

In existing 5G systems, the base station may be shared by multiple operators, but only Radio Access Network (RAN) sharing is supported in release 15(Rel 15). In a deployment scenario of such Network sharing (PLMN), a handover may occur across Public Land Mobile Networks (PLMNs). However, a Protocol Data Unit (PDU) session established by a User Equipment (UE) may be roaming-enabled (Home routed type) or roaming-not-enabled (Localbreakout type). The Home routed roaming access refers to that a roaming user accesses and acquires services provided by a Home network through a gateway (H-PGW) of the Home network. Local breakout roaming access means that a roaming user accesses and acquires corresponding services through a gateway (V-PGW) of a visited network, and a service provider can be a home network or a visited network.

If the PDU Session does not support roaming, it will become a roaming type PDU Session after handover across PLMNs is completed, i.e. the anchor Session Management Function (SMF) is still in the source PLMN, which will result in network errors, e.g. charging errors.

Disclosure of Invention

The embodiment of the application provides a session switching method and device, which are used for avoiding switching a PDU session which does not support roaming to a target PLMN when the PDU session is switched across PLMNs.

The session switching method provided by the embodiment of the application comprises the following steps:

judging whether the protocol data unit PDU session can be switched across public land mobile network PLMN or not;

and switching the PDU session capable of switching to the target PLMN, or informing the next generation access network NG RAN of the PDU session capable of switching across PLMNs.

By the method, whether the protocol data unit PDU session can be switched across the public land mobile network PLMN is judged; and switching the PDU session capable of being switched to the target PLMN, or informing the next generation access network NG RAN of the PDU session capable of being switched across the PLMN, so that the PDU session which does not support roaming is prevented from being switched to the target PLMN when the PDU session is switched across the PLMN.

Optionally, the determining whether the protocol data unit PDU session can perform a PLMN handover across a public land mobile network includes:

and if the PDU session is the PDU session allowing home routing, determining that the PDU session is switched to the target PLMN.

Optionally, before determining that the PDU session is handed over to the target PLMN, the method further includes:

and determining that the user equipment is currently in a visited public land mobile network VPLMN, and the target public land mobile network PLMN is a home public land mobile network HPLMN.

Optionally, switching the PDU session capable of being switched to the target PLMN specifically includes:

sending the PDU session capable of being switched to a target access and mobility management function (AMF) entity; or

And requesting a Session Management Function (SMF) entity to perform session update on the PDU session capable of being switched.

Optionally, the method further comprises:

requesting a Session Management Function (SMF) entity to delete the PDU session which is not allowed to be switched; or

Notifying the target NG RAN of the PDU session that cannot be handed over, such that the target NG RAN releases the air interface resources of the PDU session that cannot be handed over.

Optionally, in a session establishment or service request process, a PDU session capable of performing cross-PLMN handover is indicated to the NG RAN, so that when the NG RAN initiates the cross-PLMN handover, the PDU session capable of being handed over to the target network is carried in the to-be-handed PDU session list.

Correspondingly, another session switching method provided in the embodiment of the present application includes:

receiving a message which is sent by an access and mobility management function (AMF) entity and carries whether Protocol Data Unit (PDU) conversation can be switched across Public Land Mobile Networks (PLMN);

and when cross-PLMN switching is initiated, carrying the PDU session capable of being switched to the target network in a PDU session list to be switched according to the indication information.

Correspondingly, an embodiment of the present application provides a session switching apparatus, including:

a memory for storing program instructions;

a processor for calling the program instructions stored in the memory and executing according to the obtained program:

Optionally, before determining that the PDU session is handed over to the target PLMN, the processor is further configured to:

Optionally, the processor is further configured to call a program instruction stored in the memory, and execute, according to the obtained program:

Optionally, the processor indicates, to the NG RAN, a PDU session capable of performing cross-PLMN handover in a session establishment or service request process, so that the NG RAN carries the PDU session capable of being switched to a target network in a to-be-switched PDU session list when initiating the cross-PLMN handover.

Another session switching apparatus provided in an embodiment of the present application includes:

a memory for storing program instructions;

the judging unit is used for judging whether the protocol data unit PDU session can carry out cross-public land mobile network PLMN switching;

and the switching unit is used for switching the PDU session capable of being switched to the target PLMN or informing the next generation access network NG RAN of the PDU session capable of being switched across the PLMN.

the receiving unit is used for receiving a message which is sent by an access and mobility management function (AMF) entity and carries whether Protocol Data Unit (PDU) conversation can be switched across Public Land Mobile Networks (PLMN);

and the switching initiating unit is used for carrying the PDU session capable of being switched to the target network in a PDU session list to be switched according to the indication information when the cross-PLMN switching is initiated.

Another embodiment of the present application provides a computing device, which includes a memory and a processor, wherein the memory is used for storing program instructions, and the processor is used for calling the program instructions stored in the memory and executing any one of the above methods according to the obtained program.

Another embodiment of the present application provides a computer storage medium having stored thereon computer-executable instructions for causing a computer to perform any one of the methods described above.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a schematic diagram of a network sharing architecture according to an embodiment of the present application;

fig. 2 is a schematic diagram of an Xn handover process provided in the embodiment of the present application;

fig. 3 is a schematic diagram of an N2 handover process according to an embodiment of the present application;

fig. 4 is a schematic diagram of an Xn handover process provided in the embodiment of the present application;

fig. 5 is a schematic diagram of a PDU session establishment process according to an embodiment of the present application;

fig. 6 is a schematic diagram illustrating a service request process provided in an embodiment of the present application;

fig. 7 is a flowchart illustrating a session handover method at an AMF entity according to an embodiment of the present application;

fig. 8 is a flowchart illustrating a session handover method at the NG RAN entity side according to an embodiment of the present application;

fig. 9 is a schematic structural diagram of a session switching apparatus on the AMF entity side according to an embodiment of the present application;

fig. 10 is a schematic structural diagram of a session handover apparatus on the NG RAN entity side according to an embodiment of the present application;

fig. 11 is a schematic structural diagram of another session switching apparatus at the AMF entity side according to an embodiment of the present application.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

The method and the device are based on the same application concept, and because the principles of solving the problems of the method and the device are similar, the implementation of the device and the method can be mutually referred, and repeated parts are not repeated.

The technical scheme provided by the embodiment of the application can be suitable for various systems, particularly 5G systems. For example, the applicable system may be a global system for mobile communication (GSM) system, a Code Division Multiple Access (CDMA) system, a Wideband Code Division Multiple Access (WCDMA) General Packet Radio Service (GPRS) system, a Long Term Evolution (LTE) system, an LTE Frequency Division Duplex (FDD) system, an LTE Time Division Duplex (TDD), a Universal Mobile Telecommunications System (UMTS), a universal microwave Access (WiMAX) system, a 5G NR system, and the like. These various systems include terminal devices and network devices.

The terminal device referred to in the embodiments of the present application may refer to a device providing voice and/or data connectivity to a user, a handheld device having a wireless connection function, or other processing device connected to a wireless modem. The names of the terminal devices may also be different in different systems, for example, in a 5G system, the terminal devices may be referred to as User Equipments (UEs). Wireless terminal devices, which may be mobile terminal devices such as mobile telephones (or "cellular" telephones) and computers with mobile terminal devices, e.g., mobile devices that may be portable, pocket, hand-held, computer-included, or vehicle-mounted, communicate with one or more core networks via the RAN. Examples of such devices include Personal Communication Service (PCS) phones, cordless phones, Session Initiated Protocol (SIP) phones, Wireless Local Loop (WLL) stations, Personal Digital Assistants (PDAs), and the like. The wireless terminal device may also be referred to as a system, a subscriber unit (subscriber unit), a subscriber station (subscriber station), a mobile station (mobile), a remote station (remote station), an access point (access point), a remote terminal device (remote terminal), an access terminal device (access terminal), a user terminal device (user terminal), a user agent (user agent), and a user device (user device), which are not limited in this embodiment.

The network device according to the embodiment of the present application may be a base station, and the base station may include a plurality of cells. A base station may also be referred to as an access point, or a device in an access network that communicates over the air-interface, through one or more sectors, with wireless terminal devices, or by other names, depending on the particular application. The network device may be configured to interconvert received air frames with Internet Protocol (IP) packets as a router between the wireless terminal device and the rest of the access network, which may include an Internet Protocol (IP) communication network. The network device may also coordinate attribute management for the air interface. For example, the network device according to the embodiment of the present application may be a Base Transceiver Station (BTS) in a global system for mobile communications (GSM) or a Code Division Multiple Access (CDMA), may also be a network device (NodeB) in a Wideband Code Division Multiple Access (WCDMA), may also be an evolved network device (eNB or e-NodeB) in a long term evolution (long term evolution, LTE) system, a 5G base station in a 5G network architecture (next generation system), or may also be a home evolved node B (HeNB), a relay node (HeNB), a home base station (femto), a pico base station (pico), and the like, which are not limited in the embodiments of the present application.

Various embodiments of the present application will be described in detail below with reference to the accompanying drawings. It should be noted that the display sequence of the embodiment of the present application only represents the sequence of the embodiment, and does not represent the merits of the technical solutions provided by the embodiments.

Referring to fig. 1, a 5G network sharing architecture allows multiple operators to share network resources, mainly access network resources at present. The operators providing the shared network allocate resources to the operators participating in the sharing according to deployment, demand and SLA. In a network sharing scenario, multiple operators are allowed to use multiple PLMN IDs to differentiate their networks.

Referring to fig. 2, Xn handover refers to handover of a UE from a source NG-RAN node to a target NG-RAN node based on an Xn interface. The trigger for this process may be radio signal conditions, load balancing or due to special traffic. When switching to a shared network, the source NG-RAN needs to decide the PLMN to be used in the target network. If the serving PLMN is changed during Xn handover, the source NG-RAN node should send the PLMN used in the target network to the target NG-RAN node.

After the base station side completes the handover execution phase, the target NG-RAN sends an N2 path switching request (to-be-switched PDU session list, rejected PDU session list) to an Authentication Management Function (AMF). In the cross-PLMN handover, the selected PLMN ID is also included in the message.

After receiving the message, the AMF sends a Request (Nsmf _ PDUSESION _ UpdateSMContext Request) message for updating a PDU session management context to a related SMF for each PDU session in a PDU session list to be switched in the N2 path switching Request, wherein the message carries N3tunnel information distributed by the NG-RAN; for each PDU session in the PDU session list that is rejected in the N2 path switch request, the Nsmf _ pdusesion _ UpdateSMContextRequest message carries the value of the reason for the rejection.

For the PDU session to be switched, the SMF sends an N4 session modification request to the UPF; for the rejected PDU session, the SMF initiates a session release process or a session deactivation process after the switching is completed.

To assist the target NG-RAN in completing the reordering of packets, the UPF sends one or more "end marker" packets on the old path immediately after switching paths. The UPF starts sending downlink data to the target NG-RAN.

For each successfully transferred PDU session, the SMF sends an update PDU session management context Response (Nsmf _ PDU _ update smcontext Response) (CN tunnel information) to the AMF. For the PDU session with the user plane resource being deactivated or released, the message of Nsmf _ PDUSESION _ UpdateSMContext Response sent by the SMF to the AMF does not carry CN tunnel information, and then the SMF releases the PDU session needing to be released.

When the AMF receives Nsmf _ pdusesion _ update smcontext Response from all SMFs, the AMF collects CN tunnel information and sends the information to the target NG-RAN through an N2 path switch request acknowledgement message. If none of the requested PDU sessions are successfully transferred, the AMF sends an N2 path switch request failure message to the target NG-RAN.

The target NG-RAN sends a release resource message to the source NG-RAN to confirm that the handover was successful. This will trigger the source NG-RAN to release the resources.

The main difference between the N2 handover and the Xn handover is that the information interaction between the source NG-RAN and the target NG-RAN is through the core network. When the source NG-RAN decides to initiate an N2 Handover to the target NG-RAN, the source NG-RAN sends a Handover request (Handover Required) message to the AMF. If the source NG-RAN is switched to the shared network, the source NG-RAN also needs to determine the PLMN used by the target network, and the Handover Required message carries the PLMN ID. And the AMF sends a Handover Request to the target NG-RAN according to the target NG-RAN information in the Handover Required message.

In a network sharing scenario, if an Xn handover (Xn HO) across PLMNs occurs, the target base station may request the AMF to establish all PDU sessions. However, for non-Home routed PDU sessions, the connection between the target base station and the anchor UPF may not be established or cross-PLMN charging errors for non-Home routed PDU sessions may result.

Therefore, the embodiment of the present application provides a handover control scheme, which can avoid handover of a PDU session that does not support roaming to a target PLMN when performing handover across PLMNs. For example:

the method comprises the following steps:

in a process of switching across Public Land Mobile Networks (PLMNs), after receiving a Protocol Data Unit (PDU) session list to be switched, an AMF determines whether to switch to a target Network according to an attribute of the PDU session (for example, subscription information or Network configuration related to a Data Network name DNN of the PDU session).

For the PDU session which can be switched to the target network, the AMF continues the switching process; for the PDU session that cannot be switched, the AMF terminates the switch.

Example 1: the N2 handover process, as shown in fig. 3, specifically includes:

301. a base station in a source NG RAN initiates N2 handover, and a handover request (HO required) message carries target PLMN information.

302. And the source AMF (S-AMF) determines that cross-PLMN handover occurs according to the target PLMN information. And the S-AMF judges whether the PDU session can be switched into a target PLMN or not according to the Data Network Name (DNN) information of the PDU session in the UE context (context) aiming at the received PDU session list to be switched. The specific judgment criteria include:

the DNN of the PDU session allows home routed, and if the UE is currently in a Visited Public Land Mobile Network (VPLMN), and the target PLMN is a home PLMN (hplmn), the UE is allowed to be switched to the target PLMN, and if the UE is not in the home PLMN, the UE is not allowed to be switched to the target PLMN; or

And if the DNN of the PDU session allows home routed, the PDU session is allowed to be switched to the target PLMN, and the other conditions are not allowed.

303. And if the PDU session is the PDU session which is allowed to be switched to the target PLMN, the PDU session is sent to the target AMF (T-AMF) in a Request (Namf _ Communication _ CreateUEContext Request) message carrying AMF Communication service.

304. Continuing the subsequent process according to the existing Handover process;

305. after the S-AMF determines that the handover is completed, for example, after sending a Namf _ Communication _ N2InfoNotify ACK to the T-AMF, sending a session management context Request (Nsmf _ PDU _ Request _ release _ PDU _ context Request) message of the SMF for releasing the PDU session to the SMF, and requesting the SMF to release the PDU session which is not allowed to be handed over to the target PLMN.

S-AMF receives the SMF feedback Nsmf _ PDSSESSION _ ReleasesMContext Response.

Example 2: the Xn handover process, as shown in fig. 4, specifically includes:

401. existing handover preparation and handover execution flows.

402. The target base station sends a path switch (path switch) message to the AMF, wherein the path switch message carries the target PLMN information.

And the AMF determines that cross-PLMN switching occurs according to the target PLMN information. And the AMF judges whether the PDU session can be switched to a target PLMN or not according to the DNN information of the PDU session in the UE context aiming at the received PDU session list to be switched. The specific judgment criteria are the same as those in embodiment 1.

404 and 405. if the PDU session is a PDU session allowed to be switched to the target PLMN, the AMF sends an Nsmf _ PDUSESSion _ UpdateSMContext Request message to the SMF to complete the switching of the PDU session. The SMF sends an Nsmf _ pdusesion _ UpdateSMContext Response message to the AMF.

AMF only carries the handover completed PDU session list in the ACK message returned to the base station.

407. And the target base station deletes the empty port bearer of the PDU session which is not in the list according to the PDU session list returned by the AMF, and requests the source base station to delete all resources (release resource).

408-. AMF sends Nsmf _ PDUSESSION _ ReleasesMContext Request to SMF, SMF sends Nsmf _ PDUSESSION _ ReleasesMContext Response to AMF.

The second method comprises the following steps:

in the process of session establishment or service request, the AMF indicates to the base station which PDU sessions are the PDU sessions capable of performing cross-PLMN switching;

and when the switching is sent, the source base station determines which PDU sessions can be switched according to the indication information of the AMF, and carries the PDU sessions in a PDU session list to be switched. For PDU sessions that cannot be handed off across PLMNs, the source base station does not perform a handover.

Embodiment 3, a PDU session establishment procedure, referring to fig. 5, specifically includes:

the UE initiates a PDU session establishment (session establishment) process 501.

The AMF establishes a PDU session procedure according to the existing procedure.

The AMF determines if the PDU session supports cross-PLMN handover based on the DNN related subscription information. The AMF determines whether the PDU session supports the cross-PLMN handover in the same way.

504. If the PDU session can be switched across PLMNs, the AMF indicates in the N2 message sent to the NG-RAN.

505. And the base station stores the indication and completes the establishment of the air interface.

506 and 507, after the cross-PLMN handover trigger, the base station only includes the PDU session supporting the cross-PLMN handover in the handover request.

Embodiment 4, the service request process, referring to fig. 6, specifically includes:

601. the idle UE initiates a service request (service request) procedure and requests activation of one or a group PDU session (session).

602. For a PDU session to be activated, the AMF determines that the PDU session can be supported across PLMN handoffs.

The AMF sends an initial context setup (initial context setup) request message to the NG RAN, where the PDU session list carried therein indicates which PDU sessions can be switched across PLMNs.

604. The base station stores which PDU sessions indicated in the PDU session list can be switched across PLMNs, and air interface establishment is completed.

605- > 606. after the cross-PLMN handover trigger, the base station includes only the PDU sessions supporting the cross-PLMN handover in the handover request in the form of a PDU session list.

In summary, referring to fig. 7, on the AMF entity side, a session handover method provided in the embodiment of the present application includes:

s701, judging whether a Protocol Data Unit (PDU) session can be switched across Public Land Mobile Networks (PLMN);

s702, switching the PDU session capable of being switched to the target PLMN, or informing the next generation access network NG RAN of the PDU session capable of being switched across PLMNs.

Optionally, the method further comprises:

Correspondingly, referring to fig. 8, on the NG RAN side, a session handover method provided in an embodiment of the present application includes:

s801, receiving a message whether a Protocol Data Unit (PDU) session carrying protocol, sent by an access and mobility management function (AMF) entity, can perform cross-Public Land Mobile Network (PLMN) handover;

s802, when cross-PLMN switching is initiated, carrying the PDU session capable of being switched to the target network in a PDU session list to be switched according to the indication information.

Referring to fig. 9, on the AMF entity side, another session switching apparatus provided in an embodiment of the present application includes:

a determining unit 901, configured to determine whether a protocol data unit PDU session can perform PLMN handover across a public land mobile network;

a switching unit 902, configured to switch the PDU session capable of being switched to the target PLMN, or notify the next generation access network NG RAN of the PDU session capable of being switched across PLMNs.

Referring to fig. 10, on the NG RAN side, another session handover apparatus provided in the embodiment of the present application includes:

a receiving unit 101, configured to receive a message that whether a session carrying a protocol data unit PDU, sent by an access and mobility management function AMF entity, can perform a PLMN handover across a public land mobile network;

and the switching initiating unit 102 is configured to carry the PDU session capable of being switched to the target network in a to-be-switched PDU session list according to the indication information when the inter-PLMN switching is initiated.

It should be noted that the division of the unit in the embodiment of the present application is schematic, and is only a logic function division, and there may be another division manner in actual implementation. In addition, functional units in the embodiments of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.

The integrated unit, if implemented in the form of a software functional unit and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present application may be substantially implemented or contributed by the prior art, or all or part of the technical solution may be embodied in a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, a network device, or the like) or a processor (processor) to execute all or part of the steps of the method according to the embodiments of the present application. And the aforementioned storage medium includes: various media capable of storing program codes, such as a usb disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk, or an optical disk.

Referring to fig. 11, on the AMF entity side, another session switching apparatus provided in an embodiment of the present application includes:

a memory 111 for storing program instructions;

a processor 112, configured to call the program instructions stored in the memory, and execute, according to the obtained program:

On the NG RAN side, another session switching apparatus provided in this embodiment of the present application (the structure of which can also be referred to fig. 11) includes:

a memory for storing program instructions;

The processor may be a Central Processing Unit (CPU), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA), or a Complex Programmable Logic Device (CPLD).

The embodiment of the present application provides a computing device, which may specifically be a desktop computer, a portable computer, a smart phone, a tablet computer, a Personal Digital Assistant (PDA), and the like. The computing device may include a Central Processing Unit (CPU), memory, input/output devices, etc., the input devices may include a keyboard, mouse, touch screen, etc., and the output devices may include a Display device, such as a Liquid Crystal Display (LCD), a Cathode Ray Tube (CRT), etc.

The memory may include Read Only Memory (ROM) and Random Access Memory (RAM), and provides the processor with program instructions and data stored in the memory. In the embodiments of the present application, the memory may be used for storing a program of any one of the methods provided by the embodiments of the present application.

The processor is used for executing any one of the methods provided by the embodiment of the application according to the obtained program instructions by calling the program instructions stored in the memory.

Embodiments of the present application provide a computer storage medium for storing computer program instructions for an apparatus provided in the embodiments of the present application, which includes a program for executing any one of the methods provided in the embodiments of the present application.

The computer storage media may be any available media or data storage device that can be accessed by a computer, including, but not limited to, magnetic memory (e.g., floppy disks, hard disks, magnetic tape, magneto-optical disks (MOs), etc.), optical memory (e.g., CDs, DVDs, BDs, HVDs, etc.), and semiconductor memory (e.g., ROMs, EPROMs, EEPROMs, non-volatile memory (NAND FLASH), Solid State Disks (SSDs)), etc.

The method provided by the embodiment of the application can be applied to terminal equipment and also can be applied to network equipment.

The Terminal device may also be referred to as a User Equipment (User Equipment, abbreviated as "UE"), a Mobile Station (Mobile Station, abbreviated as "MS"), a Mobile Terminal (Mobile Terminal), or the like, and optionally, the Terminal may have a capability of communicating with one or more core networks through a Radio Access Network (RAN), for example, the Terminal may be a Mobile phone (or referred to as a "cellular" phone), a computer with Mobile property, or the like, and for example, the Terminal may also be a portable, pocket, hand-held, computer-built-in, or vehicle-mounted Mobile device.

A network device may be a base station (e.g., access point) that refers to a device in an access network that communicates over the air-interface, through one or more sectors, with wireless terminals. The base station may be configured to interconvert received air frames and IP packets as a router between the wireless terminal and the rest of the access network, which may include an Internet Protocol (IP) network. The base station may also coordinate management of attributes for the air interface. For example, the base Station may be a Base Transceiver Station (BTS) in GSM or CDMA, a base Station (NodeB) in WCDMA, an evolved Node B (NodeB or eNB or e-NodeB) in LTE, or a gNB in 5G system. The embodiments of the present application are not limited.

The above method process flow may be implemented by a software program, which may be stored in a storage medium, and when the stored software program is called, the above method steps are performed.

To sum up, in the embodiment of the present application, the AMF receives a to-be-switched PDU session list or a to-be-activated PDU session list; the AMF determines which PDU sessions in the list can be switched to the target PLMN, and the AMF switches the PDU sessions which can be switched to the target PLMN or indicates the PDU sessions to the NG RAN; the AMF requests the SMF to release the PDU session in the list that cannot be handed over to the target PLMN. And the AMF judges whether the PDU session can be switched to the target PLMN or not according to the DNN, the current PLMN information, the target PLMN information and the like. The AMF switches the PDU session capable of being switched to the target PLMN, and the method comprises the following steps: the AMF sends the PDU conversation to a target AMF; or the AMF requests the SMF for session update. The AMF releases the PDU session which can not be switched after the switching is completed. The AMF informs the target NGRAN of the PDU session which can not be switched, so that the target NGRAN releases the air interface resource of the PDU session. And the AMF indicates which PDU sessions can be switched across the PLMNs to the target NG RAN, so that the NG RAN only carries the PDU sessions which can be switched in a PDU session list to be switched when the switching across the PLMNs is triggered. In summary, the technical solution provided in the embodiment of the present application avoids switching the PDU session that does not support cross-PLMN handover to the target PLMN, thereby avoiding network errors.

As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, optical storage, and the like) having computer-usable program code embodied therein.

The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present application without departing from the spirit and scope of the application. Thus, if such modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is intended to include such modifications and variations as well.

Claims

1. A method for session handoff, the method comprising:

2. The method of claim 1, wherein determining whether a Protocol Data Unit (PDU) session can be handed over across Public Land Mobile Networks (PLMNs) comprises:

3. The method of claim 2, wherein before determining that the PDU session is handed off to the target PLMN, further comprising:

4. The method according to claim 1, wherein the handover of the handover-capable PDU session to the target PLMN specifically comprises:

5. The method of claim 1, further comprising:

6. The method of claim 1, wherein in a session establishment or service request process, a PDU session capable of performing cross-PLMN handover is indicated to the NGRAN, so that the NG RAN carries the PDU session capable of being handed over to a target network in a PDU session list to be handed over when initiating the cross-PLMN handover.

7. A method for session handoff, the method comprising:

8. A session switching apparatus, comprising:

a memory for storing program instructions;

9. The apparatus of claim 8, wherein determining whether a Protocol Data Unit (PDU) session can be handed over across Public Land Mobile Networks (PLMNs) comprises:

10. The apparatus of claim 9, wherein before determining that the PDU session is handed off to a target PLMN, the processor is further configured to:

11. The apparatus of claim 8, wherein the handover of the handover-capable PDU session to the target PLMN comprises:

12. The apparatus of claim 8, wherein the processor is further configured to call program instructions stored in the memory to perform, in accordance with the obtained program:

13. The apparatus of claim 8, wherein the processor indicates a PDU session capable of performing a cross-PLMN handover to the NG RAN during session establishment or service request, such that the NG RAN carries the PDU session capable of being handed over to a target network in a PDU session list to be handed over when initiating the cross-PLMN handover.

14. A session switching apparatus, comprising:

a memory for storing program instructions;

15. A session switching apparatus, comprising:

16. A session switching apparatus, comprising:

17. A computer storage medium having stored thereon computer-executable instructions for causing a computer to perform the method of any one of claims 1 to 7.