CN109429366B

CN109429366B - PDU session processing method and device

Info

Publication number: CN109429366B
Application number: CN201710576300.8A
Authority: CN
Inventors: 侯云静; 艾明; 王胡成
Original assignee: China Academy of Telecommunications Technology CATT
Current assignee: China Academy of Telecommunications Technology CATT; Datang Mobile Communications Equipment Co Ltd
Priority date: 2017-07-14
Filing date: 2017-07-14
Publication date: 2020-11-06
Anticipated expiration: 2037-07-14
Also published as: CN109429366A

Abstract

The invention relates to the field of wireless communication, in particular to a PDU session processing method and equipment, which are used for solving the problem that no PDU session processing method established by UE in non-3GPP access exists at present when the UE uses different VPLMNs in 3GPP access and non-3GPP access and the UE enters an idle state in the non-3GPP access. The SMF in the HPLMN receives a downlink data notification sent by a first UPF in the HPLMN; if the SMF determines that the UE is in an idle state in the non-3GPP access network, the SMF reestablishes the PDU session in the 3GPP access network. Therefore, if downlink data of the UE is received through the PDU session established in the non-3GPP access network, the embodiment of the invention provides a solution for the PDU session established in the non-3GPP access network.

Description

PDU session processing method and device

Technical Field

The present invention relates to the field of wireless communications technologies, and in particular, to a PDU session processing method and device.

Background

The fifth generation (5G) core network allows User Equipment (UE) access to the network from a 3rd generation partnership project (3 GPP) access network and also allows UE access to the network from a non-3GPP (non-3GPP) access network via an access gateway (e.g., a non-3GPP interworking function (N3 IWF)).

As shown in fig. 1, in a network architecture, User Equipment (UE) accesses the same core network through a 3GPP access technology and a non-3GPP access technology. The core network includes: access and mobility management function (AMF) network elements, Session Management Function (SMF) network elements, User Plane Function (UPF) network elements, Data Network (DN) network elements, and the like, and connection interfaces between network elements. When a UE accesses from both 3GPP and non-3GPP access networks, it typically selects N3IWF in the same Public Land Mobile Network (PLMN) as the 3GPP access network. Thus, only one AMF network element is needed in the 5G core network to perform access control management on the UE.

For a UE that is connected to both a 3GPP access and a non-3GPP access using the network architecture shown in fig. 1, if the UE enters an idle state within the non-3GPP access network. When the UPF receives downlink data of a Packet Data Unit (PDU) session established in non-3GPP access of the UE, the UPF sends a downlink data notification message to the SMF; the SMF sends an N11 request message to the AMF after receiving the downlink data notification message, and the AMF pages the UE in the 3GPP access because the UE enters an idle state in the non-3GPP access network. When UE receives paging message of AMF, UE initiates service request process through 3GPP access, service request message carries PDU conversation mark which is established in non-3GPP access and can be moved to 3GPP access. After receiving the message, the AMF judges whether the PDU session identifier of the received downlink data is in a PDU session identifier list provided by the UE, if so, the AMF continues to execute the service request process; if not, AMF returns reject message to UE and SMF respectively.

However, in a roaming scenario, when a UE accesses a 5G core network from a 3GPP access network, the UE may select an N3IWF of a different PLMN (e.g., another Visited Public Land Mobile Network (VPLMN) or a Home Public Land Mobile Network (HPLMN)) from the 3GPP access network, and at this time, the 5G core network needs to have two AMF network elements to perform access control management on the UE.

In summary, when the UE uses different VPLMNs in the 3GPP access and the non-3GPP access, there is no method for processing the PDU session established by the UE in the non-3GPP access at present if the UE enters the idle state in the non-3GPP access.

Disclosure of Invention

The invention provides a PDU session processing method and equipment, which are used for solving the problem that in the prior art, when different VPLMNs are used by UE in 3GPP access and non-3GPP access, if the UE enters an idle state in the non-3GPP access, no PDU session processing method established by the UE in the non-3GPP access exists at present.

Based on the foregoing problem, in a first aspect, an embodiment of the present invention provides a PDU session processing method, including:

an SMF in an HPLMN receives a downlink data notification sent by a first UPF in the HPLMN; the downlink data notification is sent after the first UPF receives downlink data of the UE through a PDU session established in a non-3GPP access network;

and if the SMF determines that the UE is in an idle state in the non-3GPP access network, the SMF reestablishes the PDU session in the 3GPP access network.

Optionally, the determining, by the SMF, that the UE is in an idle state in the non-3GPP access network includes:

after receiving a state notification message which is sent by an AMF (advanced mobile radio network) in a first VPLMN (virtual private local area network) and used by the non-3GPP access network and indicates that the UE is in an idle state through the SMF in the first VPLMN, the SMF determines that the UE is in the idle state in the non-3GPP access network; or

And the SMF sends a first request message containing the PDU session identifier to an AMF in the first VPLMN through the SMF in the first VPLMN used by the non-3GPP access network, and if a rejection request message which is returned by the AMF and indicates that the UE corresponding to the PDU session identifier is in an idle state is received, the UE is determined to be in the idle state in the non-3GPP access network.

Optionally, the reestablishing, by the SMF, the PDU session in the 3GPP access network includes:

the SMF informs the UE to release the PDU session established in the non-3GPP access network, and informs the UE to initiate a process of re-establishing the PDU session in the 3GPP access network.

Optionally, the informing, by the SMF, of the UE to release the PDU session established in the non-3GPP access network includes:

the SMF sends a release request message containing a PDU session identifier to an AMF in the second VPLMN through the SMF in the second VPLMN used by the 3GPP access network, so that the AMF in the second VPLMN sends the release request message to the UE, which is convenient for the UE to release the PDU session established in the non-3GPP access network after receiving the release request message.

the SMF reestablishes the PDU session within the 3GPP access network via the first UPF.

Optionally, the reestablishing, by the SMF, the PDU session through the first UPF in the 3GPP access network includes:

the SMF sends a session establishment request message containing the tunnel information of the first UPF to an AMF in a second VPLMN used by the 3GPP access network, so that the AMF determines a target SMF for establishing the PDU session in the second VPLMN after receiving the session establishment request message;

the SMF receives tunnel information of a target UPF sent by the target SMF and sends the tunnel information of the target UPF to the first UPF; wherein the target UPF is a UPF selected by the target SMF from the second VPLMN and used for establishing the PDU session.

Optionally, the sending, by the SMF, a session establishment request message including tunnel information of the first UPF to an AMF in a second VPLMN used by the 3GPP access network includes:

the SMF selects an SMF serving the UE from the second VPLMN, and sends a session establishment request message containing the tunnel information of the first UPF to the AMF in the second VPLMN; wherein the selected SMF is the same as or different from the target SMF.

In a second aspect, an embodiment of the present invention provides a PDU session processing method, including:

an AMF in a first VPLMN used by a non-3GPP access network receives a first request message which is sent by an SMF in an HPLMN through the SMF in the first VPLMN and contains a PDU session identification; wherein, the first request message is sent by the SMF in the HPLMN after receiving the downlink data notification sent by the first UPF in the HPLMN; the downlink data notification is sent after the first UPF receives downlink data of the UE through a PDU session established in the non-3GPP access network;

and if the AMF determines that the UE corresponding to the PDU session identification is in an idle state, returning a rejection request message indicating that the UE is in the idle state to the SMF in the HPLMN through the SMF in the first VPLMN, so that the SMF in the HPLMN reestablishes the PDU session in the 3GPP access network.

In a third aspect, an embodiment of the present invention provides a PDU session processing method, including:

a target SMF in a second VPLMN used by a 3GPP access network acquires tunnel information of a first UPF sent by an SMF in an HPLMN; wherein, the tunnel information of the first UPF is sent after the SMF receives a downlink data notification sent by the first UPF and determines that the UE is in an idle state in the non-3GPP access network; the downlink data notification is sent after the first UPF receives downlink data of the UE through a PDU session established in the non-3GPP access network;

and the target SMF selects a target UPF used for reestablishing the PDU session from the second VPLMN, and notifies the SMF in the HPLMN of the tunnel information of the target UPF, so that the SMF in the HPLMN sends the tunnel information of the target UPF to the first UPF.

Optionally, the obtaining, by the target SMF in the second VPLMN used by the 3GPP access network, the tunnel information of the first UPF sent by the SMF in the HPLMN includes:

the target SMF receives a session establishment request message which is sent by an SMF in the HPLMN and contains the tunnel information of the first UPF; or

The target SMF receives the tunnel information of the first UPF notified by the AMF in the second VPLMN; wherein the tunnel information of the first UPF is sent to the AMF in the second VPLMN by the SMF in the HPLMN through the SMF selected from the second VPLMN to serve the UE, and the selected SMF is different from the target SMF.

Optionally, the method further includes:

and the target SMF sends the tunnel information of the target UPF to RAN accessed by the UE through the AMF in the second VPLMN, and receives the tunnel information of the RAN returned by the AMF in the second VPLMN.

In a fourth aspect, an embodiment of the present invention provides a first SMF for PDU session processing, where the first SMF is located in an HPLMN, and includes:

the first receiving module is used for receiving a downlink data notification sent by a first UPF in the HPLMN; the downlink data notification is sent after the first UPF receives downlink data of the UE through a PDU session established in a non-3GPP access network;

and the processing module is used for reestablishing the PDU session by the SMF in the 3GPP access network if the UE is determined to be in an idle state in the non-3GPP access network.

Optionally, the processing module is specifically configured to:

after receiving a state notification message which is sent by an AMF (advanced resource management function) in a first VPLMN (virtual private local area network) and used by the non-3GPP access network and indicates that the UE is in an idle state through an SMF in the first VPLMN, determining that the UE is in the idle state in the non-3GPP access network; or

And sending a first request message containing the PDU session identifier to an AMF in the first VPLMN through an SMF in the first VPLMN used by the non-3GPP access network, and determining that the UE is in an idle state in the non-3GPP access network if a reject request message which is returned by the AMF and indicates that the UE corresponding to the PDU session identifier is in the idle state is received.

Optionally, the processing module is specifically configured to:

notifying the UE to release the PDU session established in the non-3GPP access network, and notifying the UE to initiate a process of re-establishing the PDU session in the 3GPP access network.

Optionally, the processing module is specifically configured to:

sending a release request message containing a PDU session identifier to an AMF in the second VPLMN through an SMF in the second VPLMN used by the 3GPP access network, so that the AMF in the second VPLMN sends the release request message to the UE, and the UE is convenient to release the PDU session established in the non-3GPP access network after receiving the release request message.

Optionally, the processing module is specifically configured to:

reestablishing the PDU session through the first UPF within the 3GPP access network.

Optionally, the processing module is specifically configured to:

sending a session establishment request message containing the tunnel information of the first UPF to an AMF in a second VPLMN used by the 3GPP access network, so that the AMF determines a target SMF for establishing the PDU session in the second VPLMN after receiving the session establishment request message; receiving tunnel information of a target UPF sent by the target SMF, and sending the tunnel information of the target UPF to the first UPF; wherein the target UPF is a UPF selected by the target SMF from the second VPLMN and used for establishing the PDU session.

Optionally, the processing module is specifically configured to:

selecting an SMF serving the UE from the second VPLMN, and sending a session establishment request message including tunnel information of the first UPF to an AMF in the second VPLMN; wherein the selected SMF is the same as or different from the target SMF.

In a fifth aspect, an embodiment of the present invention provides an AMF for PDU session processing, where the AMF is located in a first VPLMN used by a non-3GPP access network, and includes:

a second receiving module, configured to receive a first request message that is sent by an SMF in an HPLMN through an SMF in the first VPLMN and includes a PDU session identifier; wherein, the first request message is sent by the SMF in the HPLMN after receiving the downlink data notification sent by the first UPF in the HPLMN; the downlink data notification is sent after the first UPF receives downlink data of the UE through a PDU session established in the non-3GPP access network;

a first sending module, configured to, if it is determined that the UE corresponding to the PDU session identifier is in an idle state, send, through the SMF in the first VPLMN, a reject request message indicating that the UE is in the idle state to the SMF in the HPLMN, so that the SMF in the HPLMN reestablishes the PDU session in the 3GPP access network.

In a sixth aspect, an embodiment of the present invention provides a target SMF for PDU session processing, where the target SMF is located in a second VPLMN used by a 3GPP access network, and the target SMF includes:

the acquisition module is used for acquiring the tunnel information of the first UPF sent by the SMF in the HPLMN; wherein, the tunnel information of the first UPF is sent after the SMF receives a downlink data notification sent by the first UPF and determines that the UE is in an idle state in the non-3GPP access network; the downlink data notification is sent after the first UPF receives downlink data of the UE through a PDU session established in the non-3GPP access network;

and a second sending module, configured to select a target UPF used for reestablishing the PDU session from the second VPLMN, and notify the SMF in the HPLMN of the tunnel information of the target UPF, so that the SMF in the HPLMN sends the tunnel information of the target UPF to the first UPF.

Optionally, the obtaining module is specifically configured to:

receiving a session establishment request message which is sent by an SMF in the HPLMN and contains the tunnel information of the first UPF; or

Receiving the tunnel information of the first UPF notified by the AMF in the second VPLMN; wherein the tunnel information of the first UPF is sent to the AMF in the second VPLMN by the SMF in the HPLMN through the SMF selected from the second VPLMN to serve the UE, and the selected SMF is different from the target SMF.

Optionally, the second sending module is further configured to:

and sending the tunnel information of the target UPF to RAN accessed by the UE through the AMF in the second VPLMN, and receiving the tunnel information of the RAN returned by the AMF in the second VPLMN.

In the embodiment of the invention, when the UE uses different VPLMNs in the 3GPP access and the non-3GPP access and the UE enters an idle state in the non-3GPP access, if downlink data of the UE is received through a PDU session established in the non-3GPP access network, the SMF in the HPLMN reestablishes the PDU session in the 3GPP access network, thereby providing a PDU session processing scheme; and after the PDU session is reestablished in the 3GPP access network, downlink data of the UE is transmitted through the newly established PDU session, accurate transmission of the downlink data of the UE is ensured, and system performance is improved.

Drawings

FIG. 1 is a network architecture of the background art;

FIG. 2 is a network architecture in a roaming scenario in accordance with an embodiment of the present invention;

FIG. 3 is a system for PDU session processing according to an embodiment of the present invention;

fig. 4 is a flowchart of a method for determining, by a first SMF, that a UE is in an idle state in a non-3GPP access network according to a first embodiment of the present invention;

fig. 5 is a flowchart of a method for determining, by a first SMF, that a UE is in an idle state in a non-3GPP access network according to a second embodiment of the present invention;

fig. 6 is a flowchart of a method for reestablishing the PDU session by the first SMF in the 3GPP access network according to the first embodiment of the present invention;

fig. 7 is a flowchart of a method for reestablishing the PDU session by the first SMF in the 3GPP access network according to the second embodiment of the present invention;

fig. 8 is a flowchart of a third method for reestablishing the PDU session by the first SMF in the 3GPP access network according to the embodiment of the present invention;

fig. 9 is a schematic structural diagram of a first SMF for PDU session processing according to a first embodiment of the present invention;

fig. 10 is a schematic structural diagram of an AMF for processing a PDU session according to a first embodiment of the present invention;

fig. 11 is a schematic structural diagram of a target SMF for PDU session processing according to a first embodiment of the present invention;

fig. 12 is a schematic structural diagram of a first SMF for PDU session processing according to a second embodiment of the present invention;

fig. 13 is a schematic structural diagram of an AMF for a second PDU session processing according to an embodiment of the present invention;

fig. 14 is a schematic structural diagram of a target SMF for PDU session processing according to a second embodiment of the present invention;

fig. 15 is a flowchart of a PDU session processing method according to a first embodiment of the present invention;

fig. 16 is a flowchart of a PDU session processing method according to a second embodiment of the present invention;

fig. 17 is a flowchart of a PDU session processing method according to a third embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clearer, the present invention will be described in further detail with reference to the accompanying drawings, and it is apparent that the described embodiments are only a part of the embodiments of the present invention, 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 invention.

As shown in fig. 2, in a roaming scenario, a UE accesses different core networks through a 3GPP access technology and a non-3GPP access technology, and the difference from the non-roaming scenario shown in fig. 1 mainly shows that: the core network accessed by the 3GPP access technology is different from the core network accessed by the non-3GPP access technology in the used VPLMN, and different AMF network elements are used in different VPLMNs to manage and control the UE in a roaming scene.

It should be understood that a UE is also generally called a terminal, and a 3GPP access network element is also called an access network element (RAN), for example, a base station in 5G. A non-3GPP access network refers to an access network other than 3GPP, such as a Wireless Local Area Network (WLAN) access network. The N3IWF is similar to an evolved packet data gateway (ePDG) in LTE, and is used in 5G to establish an internet protocol security (IPsec) tunnel with a UE when the UE accesses through a non-3GPP technical network. In future 5G definitions, the name of the N3IWF may change.

The AMF network element is responsible for access management and mobility management of a terminal, and in practical application, the AMF network element includes a mobility management function in a Mobility Management Entity (MME) in a network framework in Long Term Evolution (LTE), and adds the access management function.

The SMF network element is responsible for session management, such as session establishment of a user, that is, a session management function in an MME (Mobile management entity) network element. The UPF network element is a functional network element of an end user plane, and is mainly responsible for connecting an external network, and includes related functions of a Serving Gateway (SGW) of LTE and a Public Data Network (PDN) gateway (PDN-GW). The data network element DN is responsible for a network providing service for the UE, for example, some DNs provide an internet access function for the terminal, and other DNs provide a short message function for the terminal.

As shown in fig. 3, an embodiment of the present invention provides a system for PDU session processing, including: SMF110 in HPLMN, UPF120 in HPLMN, DN 130; an SMF210 in a first VPLMN, a UPF220 in the first VPLMN, and an AMF230 in the first VPLMN used by a non-3GPP access network; SMF310 in the second VPLMN, UPF320 in the second VPLMN, and AMF330 in the second VPLMN used by the 3GPP access network; and a UE 400.

For ease of distinction, in the following description, the SMF in the HPLMN is referred to as the first SMF, and the UPF in the HPLMN is referred to as the first UPF; the SMF in the first VPLMN is called a second SMF, the UPF in the first VPLMN is called a second UPF, and the AMF in the first VPLMN is called a first AMF; the SMF in the second VPLMN is called a third SMF, the UPF in the second VPLMN is called a third UPF, and the AMF in the second VPLMN is called a second AMF.

The first SMF is used for receiving a downlink data notification sent by a first UPF in the HPLMN; if the UE is determined to be in an idle state in the non-3GPP access network, reestablishing the PDU session in the 3GPP access network;

and the downlink data notification is sent after the first UPF receives downlink data of the UE through a PDU session established by a non-3GPP access network.

Optionally, the first SMF may determine that the UE is in an idle state in the non-3GPP access network by using the following method:

in a first manner, after receiving a state notification message, which indicates that the UE is in an idle state, sent by an AMF in a first VPLMN used by the non-3GPP access network through the SMF in the first VPLMN, the first SMF determines that the UE is in an idle state in the non-3GPP access network.

Correspondingly, the AMF in the first VPLMN used by the non-3GPP access network monitors the state of the UE; and after monitoring that the UE enters an idle state, sending a state notification message which indicates that the UE is in the idle state to the SMF in the HPLMN.

Fig. 4 is a flowchart of a method for determining that a UE is in an idle state in a non-3GPP access network by a first SMF.

Step 401, the first AMF detects the state of the UE in the non-3GPP access network;

step 402, if the first AMF detects that the UE enters an idle state in the non-3GPP access network, the first AMF sends a state notification message to the first SMF;

wherein, the parameter contained in the state notification message is that the UE is in an idle state;

optionally, the status notification message further includes that the radio access type is non-3GPP access.

Step 403, the first SMF stores the state of the UE in the context of the UE;

step 404, the first SMF returns a UE status confirmation message to the first AMF.

And in a second mode, the SMF sends a first request message containing the PDU session identifier to an AMF in the first VPLMN through the SMF in the first VPLMN used by the non-3GPP access network, and if a reject request message indicating that the UE corresponding to the PDU session identifier is in an idle state is received, which is returned by the AMF, the UE is determined to be in the idle state in the non-3GPP access network.

Correspondingly, an AMF in a first VPLMN used by a non-3GPP access network receives a first request message which is sent by an SMF in an HPLMN through the SMF in the first VPLMN and contains a PDU session identification; if the UE corresponding to the PDU session identification is determined to be in an idle state, a rejection request message which is returned to the SMF in the HPLMN through the SMF in the first VPLMN and indicates that the UE is in the idle state is used for reestablishing the PDU session in the 3GPP access network by the SMF in the HPLMN;

wherein, the first request message is sent after the SMF in the HPLMN receives a downlink data notification sent by a first UPF in the HPLMN; and the downlink data notification is sent after the first UPF receives downlink data of the UE through a PDU session established by the non-3GPP access network.

It should be noted that, in the second mode, the SMF in the first VPLMN is selected from the SMFs serving the UE in the first VPLMN by the first SMF according to the local policy; the SMF in the first VPLMN may be the second SMF above.

Fig. 5 is a flowchart of a method for determining that a UE is in an idle state in a non-3GPP access network by a first SMF.

Step 501, a first UPF receives downlink data of UE through a PDU session established in a non-3GPP access network;

step 502, the first UPF sends a downlink data notification to the first SMF;

wherein, the downlink data notification includes a PDU session identifier to which the downlink data belongs;

optionally, the downlink data notification may further include an identifier of the UE;

step 503, the first SMF sends a request message to the second SMF;

PDU conversation identification that the downlink data belongs to in the request message; or may also contain the identity of the UE;

step 504, the second SMF sends an N11 request message to the first AMF;

the N11 request message is the forwarding of the request message by the SMF in the first VPLMN, and the N11 request message is the same as the information contained in the request message sent by the first SMF;

step 505, the first AMF determines the state of the UE;

step 506, if the first AMF determines that the UE is in an idle state, the first AMF returns a rejection request message to the second SMF;

wherein, the reject request message contains the information that the UE is in an idle state;

step 507, the second SMF forwards the reject request message to the first SMF.

When the first SMF of the embodiment of the present invention reestablishes the PDU session in the 3GPP access network, the following two ways may be adopted.

First, the first SMF informs the UE to release the PDU session established in the non-3GPP access network, and informs the UE to initiate a process of reestablishing the PDU session in the 3GPP access network.

It should be noted that, when notifying the UE to release the PDU session established in the non-3GPP access network and notifying the UE to initiate the process of re-establishing the PDU session in the 3GPP access network, the first SMF may specifically notify the UE to release the PDU session established in the non-3GPP access network and notify the UE to initiate the process of re-establishing the PDU session in the 3GPP access network simultaneously in one notification message; or the first SMF uses two notification messages, wherein one notification message informs the UE to release the PDU session established in the non-3GPP access network, and the other notification message informs the UE to initiate the process of reestablishing the PDU session in the 3GPP access network.

The first mode is explained in detail below.

After receiving a downlink data notification sent by a first UPF and determining that UE corresponding to downlink data enters an idle state, a first SMF sends a release request message containing a PDU session identifier to an AMF located in a second VPLMN used by a 3GPP access network through the SMF located in the second VPLMN;

correspondingly, the second AMF receives a release request message which is sent by the first SMF through the SMF selected from the second VPLMN and used for serving the UE and contains the PDU session identification;

the second AMF sends the release request message to the UE, and the UE releases the PDU session corresponding to the PDU session identification after receiving the release request message;

and, the UE initiates a procedure of re-establishing the PDU session within the 3GPP access network after releasing the PDU session.

It should be noted that, the method in the prior art is adopted in the process of initiating re-establishment of the PDU session in the 3GPP access network by the UE, and details are not described herein again.

With reference to fig. 6, a first method for the first SMF to reestablish the PDU session in the 3GPP access network according to the embodiment of the present invention is described.

601, a first UPF receives downlink data of UE received through a PDU session established in a non-3GPP access network;

step 602, the first UPF sends a downlink data notification to the first SMF;

step 603, the first SMF sends a release request message containing a PDU session identifier to the third SMF;

wherein, the release request message includes part or all of the following information:

PDU conversation release request, UE identification, PDU conversation identification;

it should be noted that, the PDU session identifier in the release request message may also be placed in the PDU session release request;

the third SMF is selected from SMFs serving the UE in the first VPLMN by the first SMF according to a local policy;

step 604, the third SMF sends an N11 request message to the second AMF;

the N11 request message includes part or all of the following information:

step 605, the second AMF sends the release request message to the UE;

step 606, the UE releases the PDU session established in the non-3GPP network;

step 607, the UE returns a session release confirmation message to the second AMF;

step 608, the second AMF returns a release confirmation message to the third SMF;

wherein the type of the release confirmation message is an N11 message;

the release confirmation message comprises a PDU session identifier and an identifier of the UE;

step 609, the third SMF forwards the release confirmation message to the first SMF;

step 610, the first SMF interacts with the first UPF to release the user interface connection of the PDU session;

step 611, the first SMF releases the locally stored information of the PDU session.

It should be noted that, after step 611, the UE initiates a process of re-establishing the PDU session in the 3GPP access network, which is the same as the process of initiating the PDU session establishment by the UE in the prior art, and is not described in detail herein.

And secondly, the first SMF reestablishes the PDU session through the first UPF in the 3GPP access network.

It should be noted that, when the first SMF re-establishes the PDU session in the 3GPP access network in the second manner, it may be regarded as transferring the establishment of the PDU session in the non-3GPP access network by the UE to the 3GPP access network.

In the second approach, the PDU session re-established by the first SMF in the 3GPP access network is the same UPF used in the HPLMN as the PDU session in the non-3GPP access network.

The PDU session reestablished in the 3GPP access network at least comprises a user plane tunnel between the first UPF in the HPLMN and the third UPF in the second VPLMN, and a user plane tunnel between the target UPF in the second VPLMN and the RAN accessed by the UE.

The process of the first SMF re-establishing the PDU session through the first UPF within the 3GPP access network is described in detail below.

1. The first SMF sends a session establishment request message containing tunnel information of the first UPF to an AMF (second AMF) in a second VPLMN used by the 3GPP access network;

accordingly, the AMF in the second VPLMN used by the 3GPP access network receives the session establishment request message sent by the SMF in the HPLMN.

Wherein, the session establishment request message contains part or all of the following information:

tunnel information of the first UPF, an identity of the UE, and a DDN (downlink data notification).

Optionally, the first SMF selects an SMF serving the UE from the second VPLMN, and sends a session establishment request message including tunnel information of the first UPF to the second AMF;

correspondingly, the second AMF receives the session establishment request message sent by the first SMF through one SMF in the second VPLMN.

That is, the session establishment request message sent by the first SMF to the second AMF needs to be forwarded through an SMF in the second VPLMN; and the SMF of the forwarded session establishment request message is selected by the first SMF from the SMFs serving the UE according to a local policy.

2. The second AMF determines a target SMF for establishing the PDU session;

note that the target SMF is selected from the second AMF. The basis for this selection can be found in the prior art method, for example, by selecting the SMF that is optimal for serving the UE from the second VPLMN.

3. The target SMF acquires tunnel information of a first UPF (unified Power Filter) sent by the first SMF and information of the first SMF;

A. if the selected SMF forwarding the session establishment request message is the target SMF, the method for the target SMF to acquire the tunnel information of the first UPF and the information of the first SMF is as follows:

the target SMF receives a session establishment request message which is sent by the first SMF and contains the tunnel information of the first UPF;

wherein, the session establishment request message further includes information of the first SMF.

When the selected SMF forwarding the session establishment request message is the target SMF, the target SMF has already received the session establishment request message sent by the first SMF, and therefore the target SMF directly acquires the tunnel information of the first UPF and the information of the first SMF from the received session establishment request message.

B. If the selected SMF forwarding the session establishment request message is not the target SMF, the target SMF acquires the tunnel information of the first UPF in the following manner:

the target SMF receives the tunnel information of the first UPF notified by the second AMF; wherein the tunnel information of the first UPF is sent to the AMF in the second VPLMN by the first SMF through the SMF selected from the second VPLMN and serving the UE;

wherein the second AMF also informs the target SMF of the information of the first SMF.

When the selected SMF for forwarding the session establishment request message is not the target SMF, the first SMF forwards the session establishment request message to the second AMF through the selected SMF; and after determining the target SMF, the second AMF informs the target SMF of the tunnel information of the first UPF and the information of the first SMF.

4. The target SMF selects a target UPF used for establishing the PDU session in the second VPLMN and distributes tunnel information for the target UPF;

5. the target SMF sends the tunnel information of the first UPF to the target UPF; the target SMF sends the tunnel information of the target UPF to the first SMF;

6. the first SMF receives the tunnel information of the target UPF sent by the target SMF and sends the tunnel information of the target UPF to the first UPF;

wherein, the steps 5 and 6 are the process of establishing the user plane tunnel between the target UPF and the first UPF.

7. The second AMF acquires tunnel information of RAN accessed by the UE;

if the UE is in a connected state in the 3GPP access, the second AMF directly acquires the RAN currently accessed by the UE;

if the UE is in an idle state in the 3GPP access, the second AMF pages the UE; correspondingly, after receiving the paging message of the second AMF, the UE sends a service request message to the second AMF through the RAN which pages the UE; the second AMF takes the RAN that transmitted the service request message of the UE as the RAN to which the UE accesses.

8. The second AMF informs the RAN accessed by the UE of the tunnel information of the target UPF;

the method for the second AMF to notify the RAN accessed by the UE of the tunnel information of the target UPF includes: the second AMF sends an N2 request message to the RAN accessed by the UE, wherein the N2 request message comprises the tunnel information of the target UPF.

9. After receiving the tunnel information of the target UPF, the RAN accessed by the UE sends the tunnel information of the RAN to a second AMF;

the mode for the RAN to send the tunnel information of the RAN to the second AMF is as follows: the RAN returns an N2 reply message to the second AMF, which contains the tunnel information of the RAN.

10. The second AMF informs the target SMF of the tunnel information of the RAN.

11. And the target SMF sends the tunnel information of the RAN accessed by the UE to the target UPF.

Wherein, the steps 7-11 are the process of establishing the user plane tunnel between the target UPF and the RAN.

It should be noted that the sequence of steps 5 and 6 and the sequence of steps 7 to 11 are not distinguished; in specific execution, the steps 5 and 6 can be executed firstly, and then the steps 7 to 11 can be executed; or firstly executing the steps 7-11 and then executing the steps 5 and 6; or the steps 5 and 6 and the steps 7 to 11 are simultaneously started to be executed.

With reference to fig. 7, a second method for the first SMF to reestablish the PDU session in the 3GPP access network according to the embodiment of the present invention is described.

It should be noted that, in this flow, the SMF that forwards the session establishment request message and is selected from the second VPLMN is the target SMF; and the UE is in an idle state in the 3GPP access.

Step 701, the first SMF sends a session establishment request message containing the tunnel information of the first UPF to the target SMF;

wherein, the session establishment request message further includes DDN (downlink data notification).

Step 702, the target SMF sends an N11 request message containing the tunnel information of the first UPF to the second AMF;

step 703, the target SMF selects the target UPF used for establishing the PDU session from the second VPLMN, and allocates tunnel information to the target UPF;

step 704, the target SMF sends the tunnel information of the target UPF to the second AMF;

step 705, the second AMF pages the UE;

step 706, the UE receives a paging message sent by the RAN;

step 707, the UE sends a service request message to a second AMF through the RAN;

step 708, the second AMF sends an N2 request message containing the tunnel information of the target UPF to the RAN;

step 709, the RAN returns an N2 request reply message containing the tunnel information of the RAN to the second AMF;

step 710, the second AMF sends the tunnel information of the RAN to the target SMF;

step 711, the target SMF sends the tunnel information of the RAN to the target UPF;

step 712, the target SMF sends the tunnel information of the first UPF to the target UPF;

step 713, the target SMF sends the tunnel information of the target UPF to the first SMF;

step 714, the first SMF sends the tunnel information of the target UPF to the first UPF.

It should be noted that steps 712-714 can also be located before step 704.

With reference to fig. 8, a third method for the first SMF to reestablish the PDU session in the 3GPP access network according to the embodiment of the present invention is described.

It should be noted that, in this flow, the SMF selected from the second VPLMN for forwarding the session establishment request message is not the target SMF; and the UE is in a connected state in the 3GPP access.

Step 801, the first SMF sends a session establishment request message containing tunnel information of the first UPF to a third SMF serving the UE, which is selected from the second VPLMN;

Step 802, the third SMF sends an N11 request message containing the tunnel information of the first UPF to the second AMF;

step 803, the second AMF determines a target SMF for establishing the PDU session;

step 804, the second AMF sends an N2 request message to the target SMF;

the N2 request message includes tunnel information of the first UPF and information of the first SMF;

step 805, the target SMF selects the target UPF used for establishing the PDU session from the second VPLMN, and allocates tunnel information to the target UPF;

step 806, the target SMF sends the tunnel information of the target UPF to the second AMF;

step 807, the second AMF sends an N2 request message containing tunnel information of the target UPF to the RAN accessed by the UE;

step 808, the RAN returns an N2 request reply message containing the tunnel information of the RAN to the second AMF;

step 809, the second AMF sends the tunnel information of the RAN to the target SMF;

step 810, the target SMF sends the tunnel information of the RAN to the target UPF;

step 811, the target SMF sends the tunnel information of the first UPF to the target UPF;

step 812, the target SMF sends the tunnel information of the target UPF to the first SMF;

step 813, the first SMF sends the tunnel information of the target UPF to the first UPF.

It should be noted that steps 811-813 can also be located before step 806.

As shown in fig. 9, a first SMF for PDU session processing according to a first embodiment of the present invention is located in an HPLMN, and the first SMF includes:

a first receiving module 901, configured to receive a downlink data notification sent by a first UPF in an HPLMN; the downlink data notification is sent after the first UPF receives downlink data of the UE through a PDU session established in a non-3GPP access network;

a processing module 902, configured to, if it is determined that the UE is in an idle state in the non-3GPP access network, reestablish the PDU session by the SMF in the 3GPP access network.

Optionally, the processing module 902 is specifically configured to:

sending a release request message containing a PDU session identifier to an AMF in a second VPLMN through an SMF in the second VPLMN used by the 3GPP access network, so that the AMF in the second VPLMN sends the release request message to the UE, and the UE releases the PDU session established in the non-3GPP access network after receiving the release request message.

Optionally, the processing module 902 is specifically configured to:

As shown in fig. 10, an AMF for PDU session processing in the first embodiment of the present invention is located in a first VPLMN used by a non-3GPP access network, and includes:

a second receiving module 1001, configured to receive a first request message that is sent by an SMF in an HPLMN through an SMF in the first VPLMN and includes a PDU session identifier; wherein, the first request message is sent by the SMF in the HPLMN after receiving the downlink data notification sent by the first UPF in the HPLMN; the downlink data notification is sent after the first UPF receives downlink data of the UE through a PDU session established in the non-3GPP access network;

a first sending module 1002, configured to, if it is determined that the UE corresponding to the PDU session identifier is in an idle state, send, through the SMF in the first VPLMN, a reject request message indicating that the UE is in the idle state to the SMF in the HPLMN, so that the SMF in the HPLMN reestablishes the PDU session in the 3GPP access network.

As shown in fig. 11, a target SMF for PDU session processing according to the first embodiment of the present invention is located in a second VPLMN used by a 3GPP access network, and the target SMF includes:

an obtaining module 1101, configured to obtain tunnel information of a first UPF sent by an SMF in an HPLMN; wherein, the tunnel information of the first UPF is sent after the SMF receives a downlink data notification sent by the first UPF and determines that the UE is in an idle state in the non-3GPP access network; the downlink data notification is sent after the first UPF receives downlink data of the UE through a PDU session established in the non-3GPP access network;

a second sending module 1102, configured to select a target UPF used for reestablishing the PDU session from the second VPLMN, and notify the SMF in the HPLMN of the tunnel information of the target UPF, so that the SMF in the HPLMN sends the tunnel information of the target UPF to the first UPF.

Optionally, the obtaining module 1101 is specifically configured to:

Optionally, the second sending module 1102 is further configured to:

As shown in fig. 12, a first SMF for PDU session processing according to a second embodiment of the present invention is located in an HPLMN, and the first SMF includes: a processor 1201, a transceiver 1202, a memory 1204;

the processor 1201 is configured to send and receive data through the transceiver 1202, and read a program in the memory 1204, and execute the following processes:

receiving a downlink data notification sent by a first UPF in the HPLMN; the downlink data notification is sent after the first UPF receives downlink data of the UE through a PDU session established in a non-3GPP access network; if the UE is determined to be in an idle state in the non-3GPP access network, the SMF reestablishes the PDU session in the 3GPP access network;

a transceiver 1202 for receiving and transmitting data under the control of the processor 1201.

Optionally, the processor 1201 is specifically configured to:

In fig. 12, a bus architecture (represented by bus 1200), bus 1200 may include any number of interconnected buses and bridges, and bus 1200 links together various circuits including one or more processors, represented by processor 1201, and memory, represented by memory 1204. The bus 1200 may also link together various other circuits such as peripherals, voltage regulators, power management circuits, and the like, which are well known in the art, and therefore, will not be described any further herein. A bus interface 1203 provides an interface between the bus 1200 and the transceiver 1202. The transceiver 1202 may be one element or multiple elements, such as multiple receivers and transmitters, providing a means for communicating with various other apparatus over a transmission medium. Data processed by the processor 1201 is transmitted over a wireless medium through the antenna 1205, and further, the antenna 1205 receives the data and transmits the data to the processor 1201.

The processor 1201 is responsible for managing the bus 1200 and general processing, and may also provide various functions including timing, peripheral interfaces, voltage regulation, power management, and other control functions. And memory 1204 may be used for storing data used by processor 1201 in performing operations.

Alternatively, the processor 1201 may be a CPU (central processing unit), an ASIC (Application specific integrated Circuit), an FPGA (Field Programmable Gate Array), or a CPLD (Complex Programmable Logic Device).

As shown in fig. 13, an AMF for PDU session processing in the second embodiment of the present invention is located in a first VPLMN used by a non-3GPP access network, and includes: a processor 1301, a transceiver 1302, a memory 1304;

the processor 1301 is configured to send and receive data through the transceiver 1302, and read a program in the memory 1304 to perform the following processes:

receiving a first request message which is sent by an SMF in the HPLMN through the SMF in the first VPLMN and contains a PDU session identification; wherein, the first request message is sent by the SMF in the HPLMN after receiving the downlink data notification sent by the first UPF in the HPLMN; the downlink data notification is sent after the first UPF receives downlink data of the UE through a PDU session established in the non-3GPP access network; if the UE corresponding to the PDU session identification is determined to be in an idle state, a rejection request message which is returned to the SMF in the HPLMN through the SMF in the first VPLMN and indicates that the UE is in the idle state is used for reestablishing the PDU session in the 3GPP access network by the SMF in the HPLMN;

a transceiver 1302 for receiving and transmitting data under the control of the processor 1301.

In fig. 13, a bus architecture (represented by bus 1300), bus 1300 may include any number of interconnected buses and bridges, bus 1300 linking together various circuits including one or more processors, represented by processor 1301, and memory, represented by memory 1304. The bus 1300 may also link together various other circuits such as peripherals, voltage regulators, power management circuits, and the like, which are well known in the art, and therefore, will not be described any further herein. A bus interface 1303 provides an interface between the bus 1300 and the transceiver 1302. The transceiver 1302 may be one element or multiple elements, such as multiple receivers and transmitters, providing a means for communicating with various other apparatus over a transmission medium. Data processed by processor 1301 is transmitted over a wireless medium through antenna 1305, which antenna 1305 also receives and transmits data to processor 1301.

The processor 1301 is responsible for managing the bus 1300 and general processing, and may provide various functions including timing, peripheral interfaces, voltage regulation, power management, and other control functions. And memory 1304 may be used to store data used by processor 1301 in performing operations.

Optionally, the processor 1301 may be a CPU, ASIC, FPGA or CPLD.

As shown in fig. 14, a target SMF for PDU session processing in the second embodiment of the present invention is located in a second VPLMN used by a 3GPP access network, and the target SMF includes: a processor 1401, a transceiver 1402, a memory 1404;

the processor 1401 is configured to transmit and receive data through the transceiver 1402, and read a program in the memory 1404, and performs the following processes:

acquiring tunnel information of a first UPF (unified power flow) sent by an SMF (short message service) in an HPLMN (local host network); wherein, the tunnel information of the first UPF is sent after the SMF receives a downlink data notification sent by the first UPF and determines that the UE is in an idle state in the non-3GPP access network; the downlink data notification is sent after the first UPF receives downlink data of the UE through a PDU session established in the non-3GPP access network; and selecting a target UPF used for reestablishing the PDU session from the second VPLMN, and notifying the tunnel information of the target UPF to the SMF in the HPLMN so that the SMF in the HPLMN sends the tunnel information of the target UPF to the first UPF.

A transceiver 1402 for receiving and transmitting data under the control of the processor 1401.

Optionally, the processor 1401 is specifically configured to:

Optionally, the processor 1401 is further configured to:

In fig. 14, a bus architecture (represented by the bus 1400), the bus 1400 may include any number of interconnected buses and bridges, and the bus 1400 links together various circuits including one or more processors, represented by the processor 1401, and memory, represented by the memory 1404. The bus 1400 may also link together various other circuits such as peripherals, voltage regulators, power management circuits, and the like, which are well known in the art, and therefore, will not be described any further herein. A bus interface 1403 provides an interface between the bus 1400 and the transceiver 1402. The transceiver 1402 may be one element or multiple elements, such as multiple receivers and transmitters, providing a means for communicating with various other apparatus over a transmission medium. Data processed by processor 1401 is transmitted over a wireless medium via antenna 1405, and further, antenna 1405 receives data and transmits data to processor 1401.

The processor 1401 is responsible for managing the bus 1400 and general processing, and may provide various functions including timing, peripheral interfaces, voltage regulation, power management, and other control functions. And memory 1404 may be used to store data used by processor 1401 in performing operations.

Alternatively, processor 1401 may be a CPU, ASIC, FPGA, or CPLD.

Based on the same inventive concept, the embodiment of the present invention further provides a first PDU session processing method, and since the device corresponding to the method is the first SMF in the system for PDU session processing in the embodiment of the present invention, and the principle of the method for solving the problem is similar to that of the system, the implementation of the method can refer to the implementation of the system, and repeated details are omitted.

As shown in fig. 15, a first PDU session processing method according to the embodiment of the present invention includes:

step 1501, receiving a downlink data notification sent by a first UPF in the HPLMN by the SMF in the HPLMN; the downlink data notification is sent after the first UPF receives downlink data of the UE through a PDU session established in a non-3GPP access network;

step 1502, if the SMF determines that the UE is in an idle state in the non-3GPP access network, the SMF reestablishes the PDU session in the 3GPP access network.

Based on the same inventive concept, the embodiment of the present invention further provides a second PDU session processing method, and since the device corresponding to the method is the first AMF in the first VPLMN in the system for PDU session processing in the embodiment of the present invention, and the principle of the method for solving the problem is similar to that of the system, the implementation of the method can refer to the implementation of the system, and repeated details are not repeated.

As shown in fig. 16, a second PDU session processing method according to the embodiment of the present invention includes:

step 1601, an AMF in a first VPLMN used by a non-3GPP access network receiving a first request message containing a PDU session identity, sent by an SMF in an HPLMN through the SMF in the first VPLMN; wherein, the first request message is sent by the SMF in the HPLMN after receiving the downlink data notification sent by the first UPF in the HPLMN; the downlink data notification is sent after the first UPF receives downlink data of the UE through a PDU session established in the non-3GPP access network;

step 1602, if the AMF determines that the UE corresponding to the PDU session identifier is in an idle state, returning a reject request message indicating that the UE is in the idle state to the SMF in the HPLMN through the SMF in the first VPLMN, so that the SMF in the HPLMN reestablishes the PDU session in the 3GPP access network.

Based on the same inventive concept, a third PDU session processing method is also provided in the embodiments of the present invention, because the device corresponding to the method is the target SMF in the second VPLMN in the system for PDU session processing in the embodiments of the present invention, and the principle of the method for solving the problem is similar to that of the system, the implementation of the method can refer to the implementation of the system, and repeated details are not repeated.

As shown in fig. 17, a third PDU session processing method according to the embodiment of the present invention includes:

step 1701, the target SMF in the second VPLMN used by the 3GPP access network obtains the tunnel information of the first UPF sent by the SMF in the HPLMN; wherein, the tunnel information of the first UPF is sent after the SMF receives a downlink data notification sent by the first UPF and determines that the UE is in an idle state in the non-3GPP access network; the downlink data notification is sent after the first UPF receives downlink data of the UE through a PDU session established in the non-3GPP access network;

step 1702, the target SMF selects a target UPF used for reestablishing the PDU session from the second VPLMN, and notifies the SMF in the HPLMN of the tunnel information of the target UPF, so that the SMF in the HPLMN sends the tunnel information of the target UPF to the first UPF.

Optionally, the method further includes:

Embodiments of the present invention also provide a storage medium, which may be non-volatile, that is, the content is not lost after power is turned off. The storage medium stores a software program, and the software program, when read and executed by one or more processors, may implement any of the above schemes for reporting a buffer status report according to the embodiments of the present invention.

The storage medium may be connected to the processor through an external interface or an internal interface. For example, the memory is a U disk, a mobile hard disk, etc., and can be connected through an external interface; for example, the memory is a memory module in the device in which the processor is located, and may be connected through an internal interface.

Embodiments of the present invention further provide a computer program product, where the software program, when being read and executed by one or more processors, may implement any of the above schemes for reporting a buffer status report in the embodiments of the present invention.

The present application is described above with reference to block diagrams and/or flowchart illustrations of methods, apparatus (systems) and/or computer program products according to embodiments of the application. It will be understood that one block of the block diagrams and/or flowchart illustrations, and combinations of blocks in the block diagrams and/or flowchart illustrations, 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, and/or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer and/or other programmable data processing apparatus, create means for implementing the functions/acts specified in the block diagrams and/or flowchart block or blocks.

Accordingly, the subject application may also be embodied in hardware and/or in software (including firmware, resident software, micro-code, etc.). Furthermore, the present application may take the form of a computer program product on a computer-usable or computer-readable storage medium having computer-usable or computer-readable program code embodied in the medium for use by or in connection with an instruction execution system. In the context of this application, a computer-usable or computer-readable medium may be any medium that can contain, store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device.

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

Claims

1. A Packet Data Unit (PDU) session processing method, comprising:

a Session Management Function (SMF) in a Home Public Land Mobile Network (HPLMN) receives a downlink data notification sent by a first User Plane Function (UPF) in the HPLMN; the downlink data notification is sent after the first UPF receives downlink data of User Equipment (UE) through a PDU session established in a non-third generation partnership project (3 GPP) access network;

if the SMF determines that the UE is in an idle state in the non-3GPP access network, the SMF reestablishes the PDU session in the 3GPP access network;

wherein the SMF reestablishing the PDU session within the 3GPP access network comprises:

the SMF informs the UE to release the PDU session established in the non-3GPP access network and informs the UE to initiate a process of reestablishing the PDU session in the 3GPP access network; or

2. The method of claim 1, wherein the SMF determining that the UE is in an idle state within a non-3GPP access network comprises:

after receiving a state notification message which is sent by an access and mobility management function (AMF) in a first Visited Public Land Mobile Network (VPLMN) and used by the non-3GPP access network through the SMF in the first VPLMN and indicates that the UE is in an idle state, the SMF determines that the UE is in the idle state in the non-3GPP access network; or

3. The method of claim 1, wherein the SMF notifying the UE to release the PDU session established at the non-3GPP access network comprises:

4. The method of claim 1, wherein the SMF reestablishes the PDU session through the first UPF within the 3GPP access network, comprising:

5. The method of claim 4, wherein the SMF sending a session setup request message containing tunnel information for the first UPF to an AMF in a second VPLMN used by the 3GPP access network comprises:

6. A Packet Data Unit (PDU) session processing method, comprising:

an access and mobility management function (AMF) in a first Visited Public Land Mobile Network (VPLMN) used by a non-third generation partnership project (3 GPP) access network receives a first request message containing a PDU session identification, which is sent by a Session Management Function (SMF) in a Home Public Land Mobile Network (HPLMN) through the SMF in the first VPLMN; the first request message is sent after an SMF in the HPLMN receives a downlink data notification sent by a first User Plane Function (UPF) in the HPLMN; the downlink data notification is sent after the first UPF receives downlink data of User Equipment (UE) through a PDU session established in the non-3GPP access network;

7. A Packet Data Unit (PDU) session processing method, comprising:

a target Session Management Function (SMF) in a second Visited Public Land Mobile Network (VPLMN) used by a third generation partnership project (3 GPP) access network acquires tunnel information of a first User Plane Function (UPF) sent by the SMF in a Home Public Land Mobile Network (HPLMN); wherein, the tunnel information of the first UPF is sent after the SMF receives a downlink data notification sent by the first UPF and determines that the user equipment UE is in an idle state in the non-3GPP access network; the downlink data notification is sent by the first UPF after receiving downlink data of the UE through a PDU session established in the non-3GPP access network;

8. The method of claim 7, wherein the obtaining, by the target SMF in the second VPLMN used by the 3GPP access network, the tunnel information for the first UPF sent by the SMF in the HPLMN comprises:

9. The method of claim 7, further comprising:

10. A first session management function, SMF, of packet data unit, PDU, session handling, wherein the first SMF is located in a home public land mobile network, HPLMN, the first SMF comprising:

the first receiving module is used for receiving a downlink data notification sent by a first user plane function UPF in the HPLMN; the downlink data notification is sent after the first UPF receives downlink data of User Equipment (UE) through a PDU session established in a non-third generation partnership project (3 GPP) access network;

a processing module, configured to, if it is determined that the UE is in an idle state in the non-3GPP access network, reestablish the PDU session by the SMF in the 3GPP access network;

wherein the processing module is specifically configured to: informing the UE to release the PDU session established in the non-3GPP access network and informing the UE to initiate a process of re-establishing the PDU session in the 3GPP access network; or

The processing module is specifically configured to: reestablishing the PDU session through the first UPF within the 3GPP access network.

11. The first SMF of claim 10, wherein the processing module is specifically configured to:

12. The first SMF of claim 10, wherein the processing module is specifically configured to:

13. The first SMF of claim 10, wherein the processing module is specifically configured to:

sending a session establishment request message containing the tunnel information of the first UPF to an AMF in a second VPLMN used by the 3GPP access network, so that the AMF determines a target SMF for establishing the PDU session in the second VPLMN after receiving the session establishment request message;

receiving tunnel information of a target UPF sent by the target SMF, and sending the tunnel information of the target UPF to the first UPF; wherein the target UPF is a UPF selected by the target SMF from the second VPLMN and used for establishing the PDU session.

14. The first SMF of claim 13, wherein the processing module is specifically configured to:

15. A mobility management function, AMF, for packet data unit, PDU, session handling, wherein the AMF is located in a first visited public land mobile network, VPLMN, used by a non-third generation partnership project, 3GPP, access network, the AMF comprising:

a second receiving module, configured to receive a first request message that is sent by a session management function SMF in a home public land mobile network HPLMN through an SMF in the first VPLMN and includes a PDU session identifier; the first request message is sent after an SMF in the HPLMN receives a downlink data notification sent by a first User Plane Function (UPF) in the HPLMN; the downlink data notification is sent after the first UPF receives downlink data of User Equipment (UE) through a PDU session established in the non-3GPP access network;

16. A target session management function, SMF, for packet data unit, PDU, session handling, wherein the target SMF is located in a second visited public land mobile network, VPLMN, used by a third generation partnership project, 3GPP, access network, the target SMF comprising:

the system comprises an acquisition module, a sending module and a receiving module, wherein the acquisition module is used for acquiring tunnel information of a first user plane function UPF sent by an SMF in a home public land mobile network HPLMN; wherein, the tunnel information of the first UPF is sent after the SMF receives a downlink data notification sent by the first UPF and determines that the user equipment UE is in an idle state in the non-3GPP access network; the downlink data notification is sent after the first UPF receives downlink data of the UE through a PDU session established in the non-3GPP access network;

17. The target SMF of claim 16, wherein said obtaining module is specifically configured to:

18. The target SMF of claim 16, wherein said second sending module is further configured to: