CN110035423B

CN110035423B - Session management method, device and system

Info

Publication number: CN110035423B
Application number: CN201811386059.3A
Authority: CN
Inventors: 朱奋勤
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2018-01-12
Filing date: 2018-11-20
Publication date: 2022-01-14
Anticipated expiration: 2038-11-20
Also published as: CN110035423A

Abstract

The embodiment of the application provides a session management method, a session management device and a session management system, which can keep service continuity after a terminal is switched from a 4G network to a 5G network. The method comprises the following steps: a mobile management network element receives an identifier of a Packet Data Network (PDN) connection from a terminal and single network slice selection auxiliary information S-NSSAI corresponding to the identifier of the PDN connection; and the mobile management network element triggers a target control plane function network element to update a user plane path of a Packet Data Unit (PDU) session corresponding to the PDN connection according to the identifier of the PDN connection and the S-NSSAI.

Description

Session management method, device and system

Technical Field

The present application relates to the field of communications technologies, and in particular, to a session management method, device, and system.

Background

In an existing architecture in which a fourth generation (4th generation, 4G) network and a fifth generation (5rd generation, 5G) network are intercommunicated, when a terminal is switched from the 4G network to the 5G network, if an access and mobility management function (AMF) network element selected by a Mobility Management Entity (MME) in the 4G network supports switching of a currently established Packet Data Network (PDN) connection to the 5G network, a session is successfully switched; if the AMF network element selected by the MME in the 4G network does not support switching of the currently established PDN connection to the 5G network, the session fails to be switched.

In the session of successful handover, for the session of the home routing mode, the initial AMF network element selected by the MME usually selects a default visited-session management function (V-SMF) network element to serve the sessions in the handover process. However, after the terminal is handed over from the 4G network to the 5G network, if the terminal initiates a registration procedure, at this time, the default V-SMF network element may not be suitable for continuing to serve these sessions, and thus, the continuity of the service may not be maintained. For the session with failed handover, the terminal and the 5G network will delete the information related to the PDN connection, respectively, which will cause the application on the PDN connection to be interrupted, so that the continuity of the service cannot be maintained.

In summary, how to maintain the continuity of the service after the terminal is switched from the 4G network to the 5G network is an urgent problem to be solved at present.

Disclosure of Invention

The embodiment of the application provides a session management method, a session management device and a session management system, which can keep service continuity after a terminal is switched from a 4G network to a 5G network.

In order to achieve the above purpose, the embodiment of the present application adopts the following technical solutions:

in a first aspect, a session management method is provided, where the method includes: a mobile management network element receives an identifier of a Packet Data Network (PDN) connection from a terminal and single network slice selection auxiliary information S-NSSAI corresponding to the identifier of the PDN connection; and the mobile management network element triggers a target control plane function network element to update a user plane path of a Packet Data Unit (PDU) session corresponding to the PDN connection according to the identifier of the PDN connection and the S-NSSAI. Based on the scheme, because the mobility management network element can obtain the identifier of the PDN connection and the S-NSSAI corresponding to the identifier of the PDN connection, and trigger the target control plane function network element to update the user plane path of the PDU session corresponding to the PDN connection according to the identifier of the PDN connection and the S-NSSAI corresponding to the identifier of the PDN connection, the target control plane function network element can make the IP address of the session not change, that is, the target control plane function network element updates the user plane path of the PDU session corresponding to the PDN connection, which can avoid interruption of the session, thereby maintaining continuity of the service. Therefore, based on the session management method, the continuity of the service can be maintained.

In one possible design, the triggering, by the mobility management element, a target control plane function element to update a user plane path of a PDU session corresponding to the PDN connection according to the identifier of the PDN connection and the S-NSSAI includes: under the condition that the PDN connection is in a home routing mode, the mobile management network element selects a target visited place session management network element for the PDU session according to the S-NSSAI; the mobile management network element acquires information of a target control plane function network element according to the identifier of the PDN connection; the mobile management network element sends a first message to the target visited place session management network element, wherein the first message is used for indicating the target visited place session management network element to establish a visited place user plane path corresponding to the PDU session and triggering the target control plane function network element corresponding to the information of the target control plane function network element to update the user plane path between the visited place and the home place corresponding to the PDU session. Based on the scheme, the mobility management network element can associate the S-NSSAI with the PDN connection according to the identification of the PDN connection and the S-NSSAI corresponding to the identification of the PDN connection, can select the target visited place session management network element for the PDU session according to the S-NSSAI, and can acquire the information of the target control plane function network element according to the identification of the PDN connection, so that the user plane path of the PDU session corresponding to the PDN connection in the home routing mode can be updated.

In one possible design, before the mobility management element sends the first message to the target visited session management element, the method further includes: and under the condition that the PDN connection is successfully switched to the PDN connection of the 5G network in the process that the terminal is switched from the fourth generation 4G network to the fifth generation 5G network, the second mobile management network element determines that the target visited place session management network element is different from the default visited place session management network element. Based on the scheme, the repeated operation risk brought by still triggering the target control plane function network element to update the user plane path of the PDU session corresponding to the PDN connection under the condition that the target visited place session management network element is the same as the default visited place session management network element can be avoided, and further the system resources can be saved.

In one possible design, the method further includes: and the mobility management network element sends a third message to a user data management network element, wherein the third message is used for informing the target control plane function network element of releasing the PDN connection or the PDU session. Based on the scheme, the PDN connection or the PDU session can be released under the condition that no interface exists between the mobile management network element and the target control plane function network element corresponding to the PDU session or the PDN connection.

In one possible design, the method further includes: and the mobility management network element sends a fourth message to the target control plane function network element, wherein the fourth message is used for releasing the PDN connection or the PDU session by the target control plane function network element. Based on the scheme, the PDN connection or the PDU session can be released under the condition that an interface exists between the mobile management network element and the target control plane function network element corresponding to the PDU session or the PDN connection.

In one possible design, the method further includes: the mobile management network element acquires allowed network slice selection auxiliary information NSSAI; in case the S-NSSAI is not included in the allowed NSSAI, the mobility management network element determines to release the PDN connection or the PDU session. Based on this scheme, it can be determined which PDN connections or PDU sessions can be released.

In one possible design, before the mobility management element triggers the target control plane function element to update the user plane path of the PDU session corresponding to the PDN connection, the method further includes: in case the S-NSSAI is included in the allowed NSSAI, the mobility management element determines a user plane path that allows updating of the PDU session. Based on this scheme, it can be determined which PDN connections can be handed over to the 5G network.

In one possible design, the receiving, by the mobility management network element, the identifier of the PDN connection and the S-NSSAI corresponding to the identifier of the PDN connection includes receiving, by the mobility management network element, a registration request from a terminal, where the registration request carries the identifier of the PDN connection and the S-NSSAI. Based on the scheme, the mobility management network element may obtain an identifier of the PDN connection and an S-NSSAI corresponding to the PDN connection, so that the PDN connection and the S-NSSAI may be associated.

In one possible design, the receiving, by the mobility management network element, the identifier of the PDN connection and the S-NSSAI corresponding to the identifier of the PDN connection includes receiving, by the mobility management network element, a session establishment request from a terminal, where the session establishment request carries the identifier of the PDN connection and the S-NSSAI. Based on the scheme, the mobility management network element may obtain an identifier of the PDN connection and an S-NSSAI corresponding to the PDN connection, so that the PDN connection and the S-NSSAI may be associated.

In one possible design, the method further includes: the mobile management network element receives a registration request from a terminal; the mobile management network element sends a registration response to the terminal, wherein the registration response carries an allowed NSSAI, and the allowed NSSAI comprises the S-NSSAI; and if the PDN connection is the PDN connection which is not successfully switched to the 5G network in the process of switching the terminal from the 4G network to the 5G network, the mobility management network element determines to release the PDN connection if the mobility management network element does not receive the session establishment request from the terminal within a preset time length. Based on the scheme, the corresponding PDU session is established after the PDU session establishment request is received, otherwise, the PDN connection is released, the PDN connection which is actually switched is the PDN connection which the terminal hopes to be switched and is allowed to be switched, and therefore the user requirement can be better met.

In one possible design, the method further includes: the mobility management network element receives indication information, where the indication information is used to indicate that the PDN connection is a PDN connection that the terminal has not successfully switched to the 5G network in the process of switching from the 4G network to the 5G network; or, the indication information is used to indicate that the PDN connection is a PDN connection successfully handed over to the 5G network in the process of handing over the terminal from the 4G network to the 5G network. Based on the scheme, the mobility management network element can know which PDN connections the terminal has not successfully switched to the 5G network in the process of switching from the 4G network to the 5G network, and which PDN connections the terminal has successfully switched to the 5G network in the process of switching from the 4G network to the 5G network.

In a second aspect, a session management method is provided, the method including: a terminal receives an identifier of a packet data network PDN connection and single network slice selection auxiliary information S-NSSAI corresponding to the identifier of the PDN connection; and the terminal sends the identifier of the PDN connection and the S-NSSAI to a mobile management network element, wherein the identifier of the PDN connection and the S-NSSAI are used for triggering a target control plane function network element to update a user plane path of a Packet Data Unit (PDU) session corresponding to the PDN connection. Based on the scheme, because the identifier of the PDN connection and the S-NSSAI are used to trigger the target control plane function network element to update the user plane path of the PDU session corresponding to the PDN connection, and the target control plane function network element may not change the IP address of the session, that is, the target control plane function network element updates the user plane path of the PDU session corresponding to the PDN connection, which may avoid interruption of the session, thereby maintaining continuity of the service. Therefore, based on the session management method, the continuity of the service can be maintained.

In one possible design, the terminal sending, to a mobility management network element, an identity of a PDN connection and an S-NSSAI corresponding to the identity of the PDN connection, including: and the terminal sends a registration request to the mobile management network element, wherein the registration request carries the identifier of the PDN connection and the S-NSSAI. Based on the scheme, the mobility management network element may obtain an identifier of the PDN connection and an S-NSSAI corresponding to the PDN connection, so that the PDN connection and the S-NSSAI may be associated.

In one possible design, the method further includes: the terminal receives a registration response from the mobile management network element, wherein the registration response carries the allowed NSSAI; in the case that the allowed NSSAI does not include the S-NSSAI, the terminal releases the PDN connection. Based on this scheme, it can be determined which PDN connections or PDU sessions can be released.

In one possible design, the method further includes: and under the condition that the PDN connection is not successfully switched to the PDN connection of the 5G network in the process that the terminal is switched from the 4G network to the 5G network and the allowed NSSAI comprises the S-NSSAI, the terminal sends a session establishment request to the mobility management network element, wherein the session establishment request carries the identification of the PDU session and is used for requesting to establish the PDU session. Based on the scheme, the PDN connection which is actually switched is the PDN connection which the terminal wants to be switched and is allowed to be switched, so that the user requirements can be better met.

In one possible design, the method further includes: the terminal receives a registration response from the mobile management network element, wherein the registration response carries a session state, and the session state comprises information indicating that the terminal releases the PDN connection or the PDU session release; and the terminal releases the PDN connection or the PDU session according to the session state. Based on this scheme, it can be determined which PDN connections or PDU sessions can be released.

In one possible design, the terminal sending, to a mobility management network element, an identity of a PDN connection and an S-NSSAI corresponding to the identity of the PDN connection, including: the terminal sends a session establishment request to the mobility management network element, wherein the session establishment request carries the identifier of the PDN connection and the S-NSSAI. Based on the scheme, the mobility management network element may obtain an identifier of the PDN connection and an S-NSSAI corresponding to the PDN connection, so that the PDN connection and the S-NSSAI may be associated.

In one possible design, before the terminal sends the session establishment request to the mobility management element, the method further includes: the terminal sends a registration request to the mobile management network element; the terminal receives a registration response from the mobile management network element, wherein the registration response carries the allowed NSSAI; the terminal sends a session establishment request to the mobility management network element, including: in case that the PDN connection is a PDN connection that the terminal has not successfully handed over to the 5G network in the handover procedure from the 4G network to the 5G network, and the allowed NSSAI includes the S-NSSAI, the terminal sends the session establishment request to the mobility management network element. . Based on the scheme, the PDN connection which is actually switched is the PDN connection which the terminal wants to be switched and is allowed to be switched, so that the user requirements can be better met.

In one possible design, the method further includes: in the case that the allowed NSSAI does not include the S-NSSAI, the terminal releases the PDN connection. Based on this scheme, it can be determined which PDN connections or PDU sessions can be released.

In a third aspect, a mobility management element is provided, where the mobility management element has a function of implementing the method according to the first aspect. The function can be realized by hardware, and can also be realized by executing corresponding software by hardware. The hardware or software includes one or more modules corresponding to the functions described above.

In a fourth aspect, a mobility management network element is provided, comprising: a processor and a memory; the memory is configured to store computer executable instructions, which when executed by the mobility management element, cause the mobility management element to perform a session management method as described in any of the above first aspects.

In a fifth aspect, there is provided a mobility management network element, comprising: a processor; the processor is configured to be coupled to the memory, and after reading the instruction in the memory, execute the session management method according to any one of the above first aspects according to the instruction.

A sixth aspect provides a computer-readable storage medium having stored therein instructions which, when run on a computer, cause the computer to perform the session management method of any one of the above first aspects.

In a seventh aspect, there is provided a computer program product comprising instructions which, when run on a computer, enable the computer to perform the session management method of any of the first aspect.

The technical effects brought by any one of the design manners in the third aspect to the seventh aspect may be referred to the technical effects brought by different design manners in the first aspect, and are not described herein again.

In an eighth aspect, a terminal is provided, which has the function of implementing the method of the second aspect. The function can be realized by hardware, and can also be realized by executing corresponding software by hardware. The hardware or software includes one or more modules corresponding to the functions described above.

In a ninth aspect, there is provided a terminal comprising: a processor and a memory; the memory is configured to store computer executable instructions, and when the terminal runs, the processor executes the computer executable instructions stored in the memory, so as to enable the terminal to execute the session management method according to any one of the first aspect.

In a tenth aspect, there is provided a terminal comprising: a processor; the processor is configured to be coupled with the memory, and after reading the instruction in the memory, execute the session management method according to any one of the second aspect.

In an eleventh aspect, there is provided a computer-readable storage medium having stored therein instructions, which when run on a computer, make the computer perform the session management method of any one of the above second aspects.

In a twelfth aspect, there is provided a computer program product comprising instructions which, when run on a computer, enable the computer to perform the session management method of any of the second aspects above.

For technical effects brought by any one of the design manners in the eighth aspect to the twelfth aspect, reference may be made to technical effects brought by different design manners in the first aspect, and details are not described herein.

In a thirteenth aspect, a session management system is provided, which includes a mobility management network element and a target control plane function network element; the mobile management network element is used for receiving an identifier of a Packet Data Network (PDN) connection from a terminal and single network slice selection auxiliary information S-NSSAI corresponding to the identifier of the PDN connection; the mobility management network element is further configured to trigger a target control plane function network element to update a user plane path of a packet data unit PDU session corresponding to the PDN connection according to the identifier of the PDN connection and the S-NSSAI; the target control plane functional network element is configured to update a user plane path of the PDU session corresponding to the PDN connection.

For technical effects of the thirteenth aspect, reference may be made to the description related to the technical effects of the first aspect, and details are not repeated here.

These and other aspects of the present application will be more readily apparent from the following description of the embodiments.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below.

FIG. 1-1 is a non-roaming schematic diagram of a conventional interworking architecture between a 4G network and a 5G network;

fig. 1-2 is a schematic diagram of a home routing mode of an existing interworking architecture between a 4G network and a 5G network;

fig. 1-3 are schematic diagrams of a 4G network and a 5G network interworking architecture that is non-roaming and includes an intermediate session management network element;

fig. 2 is a schematic architecture diagram of a session management system according to an embodiment of the present application;

fig. 3 is a schematic hardware structure diagram of a communication device according to an embodiment of the present disclosure;

fig. 4 is a first flowchart illustrating a session management method according to an embodiment of the present application;

fig. 5 is a flowchart illustrating a second session management method according to an embodiment of the present application;

fig. 6 is a third schematic flowchart of a session management method according to an embodiment of the present application;

fig. 7 is a schematic structural diagram of a mobility management element according to an embodiment of the present application;

fig. 8 is a schematic structural diagram of an apparatus according to an embodiment of the present disclosure.

Detailed Description

To facilitate understanding of the technical solutions of the embodiments of the present application, a brief description of the related art of the present application is first given as follows.

Network slicing:

a network slice (network slice) is a logically isolated network for supporting specific network capabilities and network characteristics, and may include the entire network from end to end (E2E), or a part of network functions may be shared in multiple network slices, which is a key technology for meeting the requirements of the 5G mobile communication technology proposed by 3GPP on network differentiation. Generally, the network characteristics of different network slices are different, and the network slices are required to be isolated from each other and not influenced by each other. Network slices such as enhanced (AR) or Virtual (VR) traffic require large bandwidth and low latency; the network slice of the internet of things (IOT) service requires to support mass terminal access, but has a small bandwidth and no requirement for delay.

Network Slice Selection Assistance Information (NSSAI):

multiple single NSSAIs (S-NSSAIs) are included in the NSSAI. The S-NSSAI is composed of a service type (SST) and a Slice Differentiator (SD). Wherein SST includes standardized and operator-customized types; SD is optional information that supplements SST to distinguish multiple network slices of the same SST. 23.501 the types and roles of NSSAI as defined in the Standard are shown in Table one.

Watch 1

The 4G network and 5G network intercommunication structure:

fig. 1-1 is a schematic diagram of an existing interworking non-roaming architecture between a 4G network and a 5G network. The 4G network and the 5G network share a User Plane Function (UPF) network element + a PDN gateway user plane function (PGW-U) network element, a Session Management Function (SMF) network element + a PDN gateway control plane function (PGW-C) network element, a Policy Control Function (PCF) network element + a Policy and Charging Rules Function (PCRF) network element, a Home Subscriber Server (HSS), and a Unified Data Management (UDM) network element. Here, "+" indicates a convergence, where UPF is a user plane function of a 5G network, PGW-U is a gateway user plane function of a 4G network corresponding to UPF, SMF is a session management function of the 5G network, PGW-C is a gateway control plane function in the 4G network corresponding to SMF, PCF is a policy control function of the 5G network, and PCRF is a policy charging rule function of the 4G network corresponding to PCF. In the embodiment of the present application, for convenience of description, the HSS and the UDM network element are referred to as a user data management network element, and the PGW-C network element and the SMF network element are referred to as a control plane function network element, which are described in a unified manner herein and will not be described in detail below. Of course, the combined network device may also use other names, and this embodiment of the present application is not limited to this specifically.

In addition, as shown in fig. 1-1, the interworking non-roaming architecture between the 4G network and the 5G network may further include an MME and a Serving Gateway (SGW) in the 4G network, and an AMF network element in the 5G network. Optionally, the interworking architecture between the 4G network and the 5G network may further include a network handover selection function (NSSF) network element. When the AMF network element cannot select a network slice for the terminal, the AMF network element may request the NSSF network element to select a network slice for the terminal, which is not specifically limited in this embodiment of the present application.

The terminal is accessed to the 4G network through evolved universal terrestrial radio access network (E-UTRAN) equipment, and the terminal is accessed to the 5G network through next generation radio access network (NG-RAN) equipment. The E-UTRAN device communicates with the MME through an S1-MME interface, the E-UTRAN device communicates with the SGW through an S1-U interface, the MME communicates with the SGW through an S11 interface, the MME communicates with the user data management network element through an S6a interface, the MME communicates with the AMF network element through an N26 interface, the SGW communicates with the PGW-U network element + UPF network element through an S5-U interface, the SGW communicates with the PGW-C network element + SMF network element through an S5-C interface, the PGW-U network element + UPF network element communicates with the NG-RAN device through an N3 interface, the PGW-U network element + UPF network element communicates with the PGW-C network element + SMF network element through an N4 interface, the PGW-C network element + SMF network element communicates with the PCRF network element + PCF network element through an N7 interface, the HSS + UDM network element communicates with the PGW-C + SMF network element through an N10 interface, and the AMF network element communicates with the HSS 8 interface, the PCRF network element and the PCF network element are communicated with the AMF network element through an N15 interface, the PGW-C network element and the SMF network element are communicated with the AMF network element through an N11 interface, the AMF network element is communicated with the NG-RAN equipment through an N2 interface, and the AMF network element is communicated with the terminal through an N1 interface.

Fig. 1-2 are schematic diagrams illustrating an interworking home routing mode roaming architecture between a 4G network and a 5G network. In the home and rural routing mode, a PDN connection or PDU session anchor PGW-U network element + UPF network element, an anchor PGW-C network element + SMF network element of the terminal are located in a home Public Land Mobile Network (PLMN), and an AMF providing an access service for the terminal is located in a visited PLMN. In the non-home routing mode, a PDN connection of the terminal or a PGW-U network element + UPF network element, a PGW-C network element + SMF network element anchored by a PDU session and an AMF providing access service for the terminal are located in the same PLMN. In this embodiment, the PGW-U network element + UPF network element may be referred to as an anchor user plane network element of a PDN connection or a PDU session. In order to maintain session continuity, it is necessary to ensure that when the terminal switches from 4G to 5G, the anchor user plane network element of the corresponding PDU session in 4G to 5G is switched unchanged. Since the home PGW-U network element + UPF network element cannot interface with the NG-RAN of the visited place, a visited place session management network element V-SMF and a visited place user plane function network element V-UPF are introduced in fig. 1-2, where the V-SMF selects and controls the V-UPF that interfaces with the NG-RAN. Specifically, the V-UPF and the NG-RAN are communicated through an N3 interface, the V-UPF and the PGW-U network element and the UPF network element are communicated through an N9 interface, the V-SMF is communicated with the PGW-C network element and the SMF network element through an N16 interface, and the V-SMF is communicated with the AMF through an N11 interface. In addition, in fig. 1-2, the PCRF network element + PCF network element is located in the home PLMN, the V-PCF interfaced with the AMF is located in the visited PLMN, and an interface also exists between the PCRF network element + PCF network element and the V-PCF, so that the AMF can obtain the relevant policy information from the PCRF network element + PCF network element of the home PLMN.

In addition, in the non-home routing mode, there is a scenario in which the PGW-U network element + UPF network element cannot interface with the NG-RAN accessed by the UE, and at this time, the PGW-C + SMF needs to select and interface with the NG-RAN through the intermediate UPF (I-UPF) controlled by the intermediate SMF (I-SMF), and the architecture is as shown in fig. 1 to 3. The architecture is similar to that shown in fig. 1-2, except that the PGW-C network element + SMF network element, the PGW-U network element + UPF network element, and the AMF are located in the same PLMN network in the architecture diagram. In this scenario, the functions of I-SMF and I-UPF are similar to those of V-SMF and V-UPF, respectively, and the interface Nxx between I-SMF and PGW-C + SMF network element is also similar to N16. The V-PCF does not exist in this architecture, since in one PLMN, the AMF can directly interface with PCF + PCRF.

For convenience of description, the home routing mode roaming architecture is taken as an example in the following, and it should be noted that the related description is also applicable to a scenario where the PGW-U + UPF cannot access the NG-RAN interface of the UE in the non-home routing mode.

It should be noted that the interface name between the network elements in fig. 1-1\1-2\1-3 is only an example, and the interface name in the specific implementation may be other names, which is not specifically limited in this embodiment of the present application.

It should be noted that the NG-RAN device in the 5G network may also be referred to as an access device, and the access device refers to a device accessing a core network, and may be, for example, a base station, a broadband network service gateway (BNG), a convergence switch, a non-3 GPP access device, and the like. The base stations may include various forms of base stations, such as: macro base stations, micro base stations (also referred to as small stations), relay stations, access points, and the like, which are not specifically limited in this embodiment of the present application.

Certainly, other network elements may also be in the 4G network and the 5G network, for example, the 4G network may further include a General Packet Radio System (GPRS) service support node (SGSN) and the like, and the 5G network may further include an authentication server function (AUSF) network element and the like, which is not specifically limited in this embodiment of the present application.

The technical solutions in the embodiments of the present application will be described below with reference to the drawings in the embodiments of the present application. In the description of the present application, the term "plurality" means two or more than two unless otherwise specified. In addition, in order to facilitate clear description of technical solutions of the embodiments of the present application, in the embodiments of the present application, terms such as "first" and "second" are used to distinguish the same items or similar items having substantially the same functions and actions. Those skilled in the art will appreciate that the terms "first," "second," etc. do not denote any order or quantity, nor do the terms "first," "second," etc. denote any order or importance.

The network architecture and the service scenario described in the embodiment of the present application are for more clearly illustrating the technical solution of the embodiment of the present application, and do not form a limitation on the technical solution provided in the embodiment of the present application, and as a person of ordinary skill in the art knows that along with the evolution of the network architecture and the appearance of a new service scenario, the technical solution provided in the embodiment of the present application is also applicable to similar technical problems.

Fig. 2 shows a session management system 20 according to an embodiment of the present application. The session management system 20 comprises a mobility management network element 201 and a target control plane function network element 202.

The mobility management element 201 is configured to receive an identifier of a PDN connection from a terminal and an S-NSSAI corresponding to the identifier of the PDN connection, and trigger the target control plane function element 202 to update a user plane path of a Packet Data Unit (PDU) session corresponding to the PDN connection according to the identifier of the PDN connection and the S-NSSAI.

And the target control function network element 202 is configured to update a user plane path of the PDU session corresponding to the PDN connection.

Optionally, the mobility management network element 201 and the target control plane function network element 202 in this embodiment of the application may communicate directly or communicate through forwarding of other devices, which is not specifically limited in this embodiment of the application.

Optionally, the session in this embodiment of the present application may include a PDN connection or a PDU session, which is not specifically limited in this embodiment of the present application.

Optionally, the terminal (terminal) referred to in the embodiments of the present application may include various handheld devices with wireless communication functions, vehicle-mounted devices, wearable devices, computing devices, or other processing devices connected to a wireless modem; and may further include a subscriber unit (subscriber unit), a cellular phone (cellular phone), a smart phone (smart phone), a wireless data card, a Personal Digital Assistant (PDA) computer, a tablet computer, a wireless modem (modem), a handheld device (dhhand), a laptop computer (laptop computer), a cordless phone (cordless phone) or a Wireless Local Loop (WLL) station, a Machine Type Communication (MTC) terminal, a user equipment (user equipment, UE), a Mobile Station (MS), a terminal device (terminal device), and the like. For convenience of description, the above-mentioned devices are collectively referred to as a terminal in this application.

Optionally, the mobility management network element 201 in this embodiment may be an initial mobility management network element selected when the terminal accesses the 5G network, or may be a target mobility management network element selected when the terminal accesses the 5G network, which is not specifically limited in this embodiment of the present application.

Optionally, the session management system 20 may be applied to an interworking architecture of a 4G network and a 5G network shown in fig. 1-1, fig. 1-2, and fig. 1-3, at this time, the mobility management network element 201 may correspond to the AMF network element in fig. 1-1, fig. 1-2, and fig. 1-3, and the target control plane function network element may correspond to the PGW-C network element + the SMF network element in fig. 1-1, fig. 1-2, and fig. 1-3, which is not particularly limited in this application.

In the session management system, the mobility management network element may obtain an identifier of a PDN connection and an S-NSSAI corresponding to the identifier of the PDN connection, and trigger the target control plane function network element to update a user plane path of a PDU session corresponding to the PDN connection according to the identifier of the PDN connection and the S-NSSAI corresponding to the identifier of the PDN connection, where the target control plane function network element may not change an Internet Protocol (IP) address of the session, that is, the target control plane function network element updates the user plane path of the PDU session corresponding to the PDN connection, which may avoid interruption of the session, and may maintain continuity of a service. Therefore, based on the session management method, the continuity of the service can be maintained.

Optionally, the mobility management network element 201 and the target control plane function network element 202 in fig. 2 may be implemented by one device, or may be implemented by multiple devices together, or may be one functional module in one device, which is not specifically limited in this embodiment of the present application. It is understood that the above functions may be either network elements in a hardware device, software functions running on dedicated hardware, or virtualized functions instantiated on a platform (e.g., a cloud platform).

For example, the mobility management network element 201 and the target control plane functionality network element 202 in fig. 2 may be implemented by the communication device in fig. 3. Fig. 3 is a schematic diagram illustrating a hardware structure of a communication device according to an embodiment of the present application. The communication device 300 includes at least one processor 301, communication lines 302, memory 303, and at least one communication interface 304.

The processor 301 may be a general-purpose Central Processing Unit (CPU), a microprocessor, an application-specific integrated circuit (ASIC), or one or more ics for controlling the execution of programs in accordance with the present disclosure.

The communication link 302 may include a path for transmitting information between the aforementioned components.

The communication interface 304 may be any device, such as a transceiver, for communicating with other devices or communication networks, such as an ethernet, a Radio Access Network (RAN), a Wireless Local Area Network (WLAN), etc.

The memory 303 may be, but is not limited to, a read-only memory (ROM) or other type of static storage device that may store static information and instructions, a Random Access Memory (RAM) or other type of dynamic storage device that may store information and instructions, an electrically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM) or other optical disk storage, optical disk storage (including compact disc, laser disc, optical disc, digital versatile disc, blu-ray disc, etc.), magnetic disk storage media or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. The memory may be separate and coupled to the processor via a communication line 302. The memory may also be integral to the processor.

The memory 303 is used for storing computer-executable instructions for executing the present invention, and is controlled by the processor 301. Processor 301 is configured to execute computer-executable instructions stored in memory 303 to implement the session management methods provided by the embodiments described below in the present application.

Optionally, the computer-executable instructions in the embodiments of the present application may also be referred to as application program codes, which are not specifically limited in the embodiments of the present application.

In particular implementations, processor 301 may include one or more CPUs such as CPU0 and CPU1 in fig. 3, for example, as an example.

In particular implementations, communication device 300 may include multiple processors, such as processor 301 and processor 308 in fig. 3, for example, as an example. Each of these processors may be a single-core (single-CPU) processor or a multi-core (multi-CPU) processor. A processor herein may refer to one or more devices, circuits, and/or processing cores for processing data (e.g., computer program instructions).

In particular implementations, communication device 300 may also include an output device 305 and an input device 306, as one embodiment. The output device 305 is in communication with the processor 301 and may display information in a variety of ways. For example, the output device 305 may be a Liquid Crystal Display (LCD), a Light Emitting Diode (LED) display device, a Cathode Ray Tube (CRT) display device, a projector (projector), or the like. The input device 306 is in communication with the processor 301 and may receive user input in a variety of ways. For example, the input device 306 may be a mouse, a keyboard, a touch screen device, or a sensing device, among others.

The communication device 300 may be a general purpose device or a special purpose device. In a specific implementation, the communication device 300 may be a desktop, a laptop, a web server, a Personal Digital Assistant (PDA), a mobile phone, a tablet, a wireless terminal device, an embedded device, or a device with a similar structure as in fig. 3. The embodiment of the present application does not limit the type of the communication device 300.

The following specifically explains the session management method provided in the embodiment of the present application.

It should be noted that, in the following embodiments of the present application, names of messages between network elements or names of parameters in messages are only an example, and other names may also be used in a specific implementation, which is not specifically limited in this embodiment of the present application.

Taking the application of the session management system shown in fig. 2 to the non-roaming architecture in which the 4G network and the 5G network are intercommunicated as shown in fig. 1-1 and the home routing architecture in which the 4G network and the 5G network are intercommunicated as shown in fig. 1-2 as an example, as shown in fig. 4, the session management method provided by the embodiment of the present application includes the following steps;

s401, the terminal is switched to the 5G network from the 4G network.

In this embodiment of the present application, when the terminal is switched from the 4G network to the 5G network, the MME selects a first AMF network element for the terminal, where the first AMF network element may also be referred to as an initial AMF network element, and this is not specifically limited in this embodiment of the present application.

In this embodiment of the application, when the terminal is switched from the 4G network to the 5G network, the MME further sends information of the PDN connection (i.e., a context of the PDN connection or a session context) to the first AMF network element, and the information is stored by the first AMF network element. The information of the PDN connection may include, for example, an International Mobile Subscriber Identity (IMSI), a default bearer identifier and/or an Access Point Name (APN) of the PDN connection, information and a tunnel identifier of an SMF network element + a PGW-C network element corresponding to the PDN connection, an IP address and a tunnel identifier of an SGW corresponding to the PDN connection, and an Aggregate Maximum Bit Rate (AMBR) of the PDN connection, which is not specifically limited in this embodiment of the present application. The information of the SMF network element and the PGW-C network element may be, for example, an IP address or a Full Qualified Domain Name (FQDN) of the SMF network element and the PGW-C network element, which is not specifically limited in this embodiment of the present application.

In this embodiment of the application, the first AMF network element may determine, according to the stored information of PDN connections, which PDN connections may be successfully switched to the 5G network. For example, if the first AMF network element determines that the first AMF network element has a signaling interface with the PGW-C network element and the SMF network element according to the information of the SMF network element and the PGW-C network element (for example, the two are in the same network slice), the first AMF network element determines that the PDN connection can be switched to the 5G network; or, the first AMF network element first determines, according to the information of the SMF network element and the PGW-C network element (e.g., the FQDN of the SMF network element and the PGW-C network element), the S-NSSAI corresponding to the PDN connection, and then determines, according to the S-NSSAI corresponding to the PDN connection, whether to allow the PDN connection to be switched, and so on. Further, if the first AMF network determines that some PDN connections cannot be handed over to the 5G network, the first AMF network element does not release information of the unsuccessfully handed over PDN connections, but continues to store the information of the unsuccessfully handed over PDN connections, so as to recover the unsuccessfully handed over sessions as much as possible in the registration procedure after the handover is completed. Similarly, if the terminal determines that the PDN connection cannot be successfully switched to the 5G network (for example, the terminal does not receive the radio bearer information corresponding to the session, i.e., the resources) or the terminal receives an indication that the PDN connection on the terminal is not released (i.e., the context of the PDN connection or the session context), the terminal still continues to store the information of the corresponding PDN connection, so as to recover the unsuccessfully switched sessions as much as possible in the registration procedure after the completion of the switching. The information of the PDN connection stored in the terminal may include, for example, a default bearer identifier and/or APN of the PDN connection, a type of the PDN connection, an IP address corresponding to the PDN connection, a packet filter template (TFT) for associating a packet with a specific quality of service (QoS) bearer, and an AMBR of the PDN connection, which is not specifically limited in this embodiment. The type of the PDN connection may be, for example, internet protocol version4 (IPv 4) or internet protocol version 6(internet protocol version4, IPv6), and the like, which is not specifically limited in this embodiment of the present invention.

The related process of switching the terminal from the 4G network to the 5G network may refer to an existing implementation manner, and is not described herein again.

S402, after the handover procedure is finished, the terminal sends a registration request to the first AMF network element, so that the first AMF network element receives the registration request from the terminal.

The registration request carries the NSSAI (requested NSSAI) requested by the terminal, and the corresponding relationship between each S-NSSAI in the NSSAI requested by the terminal and the identifier of the corresponding PDN connection. The NSSAI requested by the terminal includes all S-NSSAIs corresponding to PDN connections that need to be handed over to the 5G network. The S-NSSAIs corresponding to all PDN connections that need to be switched to the 5G network may include S-NSSAIs corresponding to PDN connections successfully switched in the switching procedure of step S401, may also include S-NSSAIs corresponding to PDN connections unsuccessfully switched in the switching procedure of step S401, and may also include newly added S-NSSAIs, which is not specifically limited in this embodiment of the application. The correspondence between the S-NSSAI and the identifier of the corresponding PDN connection is used for the subsequent second AMF network element to associate the S-NSSAI with the PDN connection, which is described in a unified manner herein and will not be described again.

Optionally, in this embodiment of the present application, the identifier of the PDN connection may be, for example, a default bearer identifier corresponding to the PDN connection or an APN corresponding to the PDN connection, which is not specifically limited in this embodiment of the present application.

Optionally, in this embodiment of the present application, the registration request may also carry a PDU session identifier corresponding to the PDN connection, which is not specifically limited in this embodiment of the present application.

S403, the first AMF network element obtains the subscription data of the terminal from the HSS + UDM network element.

In this embodiment, the subscription data of the terminal may include, for example, NSSAI signed by the terminal, which may refer to the existing implementation manner specifically and will not be described herein again.

It should be noted that step S403 in this embodiment is an optional step, and if the first AMF network element already stores the 5G subscription data of the terminal at this time, step S403 may not be executed, which is described in a unified manner herein and will not be described again.

S404, the first AMF network element obtains the information of the second AMF network element according to the NSSAI requested by the terminal and the NSSAI signed by the terminal.

Optionally, in this embodiment of the application, the obtaining, by the first AMF network element, the information of the second AMF network element according to the NSSAI requested by the terminal and the NSSAI subscribed by the terminal may specifically include: the method comprises the steps that a first AMF network element sends slice selection request information to an NSSF network element, the slice selection request information carries NSSAI requested by a terminal and NSSAI signed by the terminal, the NSSF network element determines information of a second AMF network element or information of a second AMF network element set and allowed NSSAI (allowed NSSAI) according to the NSSAI requested by the terminal and the NSSAI signed by the terminal, and then sends the information of the second AMF network element or the information of the second AMF network element set and the allowed NSSAI to the first AMF network element; if the NSSF network element selects the set of the second AMF network elements, the first AMF network element selects one second AMF network element from the set of the second AMF network elements, which is not specifically limited in this embodiment of the present application.

Of course, the first AMF network element may further determine the information of the second AMF network element in combination with other information or in other manners, for example, the first AMF network element may further determine the information of the second AMF network element according to the network slice configured in the first AMF network element, the mapping information of the AMF network element set, or the location information of the terminal, which may specifically refer to the existing implementation manner and is not described herein again.

Optionally, in this embodiment of the application, if the first AMF network element may support NSSAI supported by all subscriptions requested by the terminal, the first AMF network element may also determine that the second AMF network element does not need to be selected. At this time, the second AMF network element in this embodiment is an AMF network element of the mobility management network element 20 in the session management system 20 shown in fig. 2 in an architecture in which a 4G network and a 5G network are intercommunicated, which is described in a unified manner herein and will not be described again.

It should be noted that fig. 1-1 and fig. 1-2 only show an example of a connection manner of the AMF network element in the interworking architectures of the 4G network and the 5G network. When there are multiple AMF network elements, the connection mode of each AMF network element in the interworking architecture between the 4G network and the 5G network can refer to the AMF network elements shown in fig. 1-1 and fig. 1-2, which is not described herein again. Meanwhile, different AMF network elements may communicate with each other through an N14 interface, which is described herein in a unified manner and will not be described in detail below.

S405, the first AMF network element sends a redirected registration request to the second AMF network element, so that the second AMF network element receives the redirected registration request from the first AMF network element.

The redirected registration request may carry information such as an allowed NSSAI (allowed NSSAI), a correspondence between each S-NSSAI and an identifier of a corresponding PDN connection, and a session context of a terminal corresponding to each S-NSSAI, which is stored in the first AMF network element, which is not specifically limited in this embodiment of the present application.

The allowed NSSAI is an NSSAI included in the terminal subscription, an NSSAI included in the terminal request, and an NSSAI supported by the second AMF network element, and is herein described in a unified manner and will not be described again.

The session context of the terminal corresponding to each S-NSSAI may include not only the context of the PDN connection that is not successfully handed over, but also the context of the PDU session that is successfully handed over, which is not specifically limited in this embodiment of the present application. For the description of the context of the PDN connection that is not successfully handed over, reference may be made to the description of the context of the PDN connection stored in the first AMF network element in step S401, which is not described herein again. The context of the PDU session successfully switched stored in the first AMF network element may include, for example, a PDU session identifier, an S-NSSAI, a Data Network Name (DNN), a PGW-C network element + an SMF network element, and the like, and if the session is in a home routing mode, the context of the PDU session may also include information of a visited SMF (visited SMF, V-SMF) network element selected by the first AMF network element, which may specifically refer to the existing description and is not described herein again.

It should be noted that, in the embodiment of the present application, the V-SMF network element may be an SMF network element deployed in combination with the PGW-C, or may be an SMF network element deployed independently, which is not specifically limited in the embodiment of the present application. The description is unified here and will not be repeated below.

Optionally, in this embodiment of the application, the first AMF network element may directly send the redirect registration request to the second AMF network element, or may send the redirect registration request to the second AMF network element through the access network element, which is not specifically limited in this embodiment of the application.

Optionally, in this embodiment of the application, the first mobility management network element may further carry indication information in the redirection registration request, where the indication information is used to indicate that the PDN connection is a PDN connection that is not successfully switched to the 5G network in a process of switching the terminal from the 4G network to the network; or the indication information is used to indicate that the PDN connection is a PDN connection successfully handed over to the 5G network in a process of handing over the terminal from the 4G network to the 5G network, which is not specifically limited in this embodiment of the present application.

For example, in a possible implementation manner, the method of the indication information may be to display the indication information, for example, add a list of unsuccessfully or successfully switched PDN connections outside the context of the PDN connection, where the list includes a default bearer identifier or a PDU session identifier corresponding to the unsuccessfully or successfully switched PDN connection.

In another possible implementation manner, the indication information may be implicit indication information, for example, different types are used to identify the session context, if the session context is a PDN connection context, the handover is not successful, and if the session context is a PDU session context, the handover is successful.

The embodiment of the present application does not specifically limit how the first mobility management network element indicates a successfully switched PDN connection or an unsuccessfully switched PDN connection when the PDN connection is established.

Taking an S-NSSAI as an example, the session management method further includes the following steps:

and S406, the second AMF network element determines whether to allow updating of the user plane path of the PDU session corresponding to the S-NSSAI according to the allowed NSSAI.

For example, if the allowed NSSAI includes the S-NSSAI, determining a user plane path allowing updating of the PDU session corresponding to the S-NSSAI; otherwise, determining that the user plane path of the PDU session corresponding to the S-NSSAI is not allowed to be updated.

In the embodiment of the present application, the user plane path allowing updating of the PDU session corresponding to the S-NSSAI may also represent that switching from the 4G network to the 5G network is allowed; the user plane path that does not allow updating of the PDU session corresponding to the S-NSSAI may also represent that switching from the 4G network to the 5G network is not allowed, which is described herein in a unified manner and will not be described again.

Wherein, for the PDN connection or PDU session in home routed mode that allows updating the user plane path of the PDU session corresponding to the S-NSSAI, the session management method further includes the following steps S407a-S412 a; for the PDU session that has been successfully switched to the 5G network for the user plane path allowing updating of the PDU session corresponding to the S-NSSAI, if the PDU session is in the non-home routing mode and does not require selecting I-SMF, the session management method further includes the following steps S407b-S408 b; for the unsuccessful handover of the user plane path allowing updating the PDU session corresponding to the S-NSSAI to the PDN connection of the 5G network, if the PDN connection is in the non-home routing mode and does not require selecting I-SMF, the session management method further includes the following steps S407c-S409 c; for PDN connections or PDU sessions of the user plane path not allowed to update the PDU session corresponding to the S-NSSAI, the session management method further includes the following steps S415-S416.

The following description of the steps S407a-S412a is given:

and S407a, the second AMF network element selects the V-SMF network element for the PDU session according to the S-NSSAI.

For example, the second AMF network element may select a V-SMF network element for the PDU session in a network slice corresponding to the S-NSSAI.

And S408a, the second AMF network element acquires the information of the PGW-C network element and the SMF network element according to the identification of the PDN connection.

For example, the second AMF network element may search for a context of the corresponding PDN connection according to the identifier of the PDN connection, and further may obtain information of the PGW-C network element + the SMF network element from the context of the PDN connection.

S409a, the second mobility management network element sends a session establishment request to the V-SMF network element, so that the V-SMF network element receives the session establishment request from the second mobility management network element.

The session establishment request is used for indicating the V-SMF network element to establish a visited place user plane path corresponding to the PDU session and triggering the V-SMF network element to update the user plane path between the visited place and the home place corresponding to the PDU session.

S410a, the V-SMF network element establishes a visited place user plane path corresponding to the PDU session.

For example, the procedure of the V-SMF network element establishing the visited user plane path corresponding to the PDU session may be as follows:

after the V-SMF network element selects the V-UPF network element according to the terminal location information, at least one of the S-NSSAI or the DNN (i.e., APN), an N4 session establishment request is sent to the V-UPF network element to create an uplink tunnel between the V-UPF network element and the current access network element of the terminal and create a downlink tunnel between the V-UPF network element and the PGW-U network element + UPF network element.

Optionally, the V-UPF network element in the embodiment of the present application may be deployed in combination with the PGW-U network element, or may be deployed independently, which is not specifically limited in the embodiment of the present application.

S411a, the V-SMF network element sends a session update request to the PGW-C network element + SMF network element, so that the PGW-C network element + SMF network element receives the session update request from the V-SMF network element.

The session update request is used for triggering the PGW-C network element and the SMF network element to update the user plane path between the visited place and the home place corresponding to the PDU session.

Optionally, the session update request may carry downlink tunnel information of the V-UPF network element, where the downlink tunnel information of the V-UPF network element may include, for example, a tunnel identifier of an N9 tunnel between the V-UPF network element and the PGW-U network element + UPF network element on the V-UPF network element side, where the tunnel identifier may include, for example, an end point address or an end point identifier, and the end point identifier may be, for example, a tunnel end point identifier (TEID), and this is not specifically limited in this embodiment of the present application.

And S412a, the PGW-C network element and the SMF network element update the user plane path between the visited place and the home place corresponding to the PDU session.

For example, the procedure of updating the user plane path between the visited place and the home place corresponding to the PDU session by the PGW-C network element + SMF network element may be as follows:

the method comprises the steps that a PGW-C network element and an SMF network element send an N4 session updating request to a PGW-U network element and a UPF network element, wherein the N4 session updating request carries downlink tunnel information of a V-UPF network element and is used for establishing an N9 tunnel between the V-UPF network element and the PGW-U network element and the UPF network element; and the PGW-C network element + SMF network element sends uplink tunnel information of the PGW-U network element + UPF network element to the V-SMF network element to establish an N9 tunnel between the V-UPF network element and the PGW-U network element + UPF network element, and the specific implementation of tunnel establishment may refer to the existing flow, and is not described herein again. The uplink tunnel information of the PGW-U network element + UPF network element may include, for example, a tunnel identifier of an N9 tunnel between the V-UPF network element and the PGW-U network element + UPF network element at the PGW-U network element + UPF network element side, where the tunnel identifier may include, for example, an end point address or an end point identifier, and the end point identifier may be, for example, a TEID, and this embodiment of the present application is not specifically limited to this.

Optionally, in this embodiment of the application, the V-SMF network element further triggers establishment of a tunnel between the V-UPF network element and the access network element, and triggers the access network element to allocate radio resources for the PDU session.

The PGW-C network element + SMF network element in S407a-S412a are the PGW-C network element + SMF network element of the terminal home location, and are described in a unified manner here, and details are not described again below.

It should be noted that the steps S407a-S412a are not only applicable to the sessions that allow the handover to the 5G network and that have not successfully handed over to the 5G network, but also applicable to the sessions that allow the handover to the 5G network and that have successfully handed over to the 5G network, and this is not particularly limited in the embodiment of the present application.

Before performing step S407a, for sessions that are allowed to be handed over to the 5G network and have successfully handed over to the 5G network, the second AMF network element may further determine whether a V-SMF network element needs to be selected for the PDU session, and in a case that the V-SMF network element needs to be selected for the PDU session, steps 407a to S412a are performed, which is not specifically limited in this embodiment of the application. For example, if the second AMF network element determines that the network slice instance in which the V-SMF network element selected in the handover process of step S401 is located is different from the network slice instance selected by the NSSF network element, the second AMF network element determines that the V-SMF network element needs to be reselected for the PDU session; or, according to the configuration, if the V-SMF network element selected in the handover process of step S401 is a temporary SMF network element configured by the system for use in handover, the second AMF always needs to reselect the V-SMF network element. Of course, if the second AMF network element determines that the network slice instance in which the V-SMF network element selected in the handover process of step S401 is located is the same as the network slice instance selected by the NSSF network element, the second AMF network element may not need to re-establish the V-SMF network element for the PDU session. The session management method corresponding to the V-SMF network element that does not need to be reselected may refer to the existing flow, which is not described herein again.

In addition, in this embodiment of the present application, for sessions that are allowed to be switched to the 5G network and that have been successfully switched to the 5G network, after the V-SMF network element successfully establishes a visited-place user plane path corresponding to the PDU session, the second AMF network element may notify the V-SMF network element selected in the switching process of step S401 to release the corresponding session, which is not specifically limited in this embodiment of the present application.

The following description of the steps S407b-S408b is given:

s407b and step S408a, the related description may refer to step S408a, and will not be repeated herein.

S408b, the second AMF network element sends the notification message 1 to the PGW-C network element + SMF network element, so that the PGW-C network element + SMF network element receives the notification message 1 from the PGW-C network element + SMF network element.

The notification message 1 carries information of the second AMF network element, so that the corresponding second AMF network element can be found according to the information of the second AMF network element when the downlink message needs to be sent.

The PGW-C network element + SMF network element in steps S407b-S412b are the PGW-C network element + SMF network element in the network where the terminal is currently located, and are described in a unified manner here, and details are not described below.

The following description of the steps S407c-S409c is given:

s407c and step S408a, the related description may refer to step S408a, and will not be repeated herein.

S408C, the second AMF network element sends the session update request to the PGW-C network element + SMF network element, so that the PGW-C network element + SMF network element receives the session update request from the second AMF network element.

And the session updating request is used for triggering the PGW-C network element and the SMF network element to update the user plane path corresponding to the PDU session.

And S409C, and the PGW-C network element and the SMF network element update the user plane path corresponding to the PDU session.

For example, the process of updating the user plane path corresponding to the PDU session by the PGW-C network element + SMF network element may be as follows:

the method comprises the steps that a PGW-C network element and an SMF network element determine whether a middle UPF network element needs to be selected or not according to the position of a terminal and the service area of the PGW-U network element and the UPF network element, if the PGW-C network element and the SMF network element determine that the middle UPF network element needs to be selected, after the PGW-C network element and the SMF network element select the middle UPF network element, an N4 session establishment request is sent to the middle UPF network element to establish a tunnel between the middle UPF network element and the PGW-U network element and the UPF network element, the PGW-C network element and the SMF network element trigger establishment of the tunnel between the middle UPF network element and an access network element, and trigger the access network element to allocate wireless resources to the PDU session; and if the PGW-C network element and the SMF network element determine that the middle UPF network element does not need to be selected, triggering the establishment of a tunnel between the PGW-U network element and the UPF network element and the access network element by the PGW-C network element and the SMF network element, and triggering the access network element to allocate radio resources for the PDU session. The specific implementation of tunnel establishment may refer to the existing flow, and is not described herein again.

Optionally, the intermediate UPF network element in the embodiment of the present application may be deployed in combination with the PGW-U network element, or may be deployed independently, which is not specifically limited in the embodiment of the present application.

The PGW-C network element + SMF network element in steps S407C-S409C are the PGW-C network element + SMF network element in the network where the terminal is currently located, and are described in a unified manner here, and details are not described below.

Further, the session management method may further include the steps of:

s413, the second AMF network element sends a registration response to the terminal, so that the terminal receives the registration response from the AMF network element.

Wherein, the registration response carries the allowed NSSAI and the PDU session state set according to the result of the session switching. Wherein, for those PDN connections or PDU sessions of the user plane path which do not allow updating PDU session corresponding to S-NSSAI; or allow to update the user plane path of the PDU session corresponding to the S-NSSAI, but switch the failed PDN connection or PDU session in the above switching procedure, the second AMF network element may instruct the terminal to release the PDN connection or PDU session in the PDU session state.

And S414, the terminal releases the corresponding PDN connection or PDU conversation according to the PDU conversation state.

PDN connections or PDU sessions for those user plane paths that do not allow updating of PDU sessions corresponding to S-NSSAI; or allowing to update the user plane path of the PDU session corresponding to the S-NSSAI, but switching the failed PDN connection or PDU session in the above switching procedure, the session management method provided in the embodiment of the present application further includes the following steps:

s415, if there is no interface between the second AMF network element and the PGW-C network element + SMF network element corresponding to the PDU session or PDN connection, the second AMF network element sends the notification message 2 to the HSS + UDM network element, so that the HSS + UDM network element receives the notification message 2 from the second AMF network element.

The notification message 2 is used to instruct the HSS and the UDM network element to notify the PGW-C network element and the SMF network element to release a corresponding PDN connection or PDU session. Meanwhile, the notification message 2 is further used to instruct the HSS + UDM network element to delete the context corresponding to the session stored in the HSS + UDM network element, which is not specifically limited in this embodiment of the present application.

In this embodiment of the present application, the notification message 2 carries an APN corresponding to a PDN connection or a PDU session that needs to be released, so that the HSS + UDM network element searches for information of a PGW-C network element + SMF corresponding to the PDN connection or the PDU session according to the APN, which is described in a unified manner herein and is not described in detail below.

Optionally, in this embodiment of the present application, the notification message 2 may further carry a default bearer identifier or a PDU session identifier corresponding to a PDN connection or a PDU session that needs to be released, which is not specifically limited in this embodiment of the present application.

And S416, the HSS + UDM network element sends a notification message 3 to the PGW-C network element and the SMF network element, so that the PGW-C network element and the SMF network element receive the notification message 3 from the HSS + UDM network element.

Wherein, the notification message 3 is used to instruct the PGW-C network element + SMF network element to release the corresponding PDN connection or PDU session.

In this embodiment of the present application, the notification message 3 carries an APN corresponding to a PDN connection or a PDU session that needs to be released, so that the PGW-C network element + SMF network element searches for PGW-C network element + SMF information corresponding to the PDN connection or the PDU session according to the APN, which is described in a unified manner herein and is not described in detail below.

Optionally, in this embodiment of the application, if the notification message 2 may further carry a default bearer identifier or a PDU session identifier corresponding to the PDN connection or the PDU session that needs to be released, the notification message 3 may further carry a default bearer identifier or a PDU session identifier corresponding to the PDN connection or the PDU session that needs to be released, so that the PGW-C network element + the SMF network element determines the PDN connection or the PDU session to be released, where this is not specifically limited in this embodiment of the application.

Optionally, the notification message 2 and the notification message 3 in the embodiment of the present application may carry an indication for notifying the PGW-C network element + SMF network element to release the corresponding PDN connection or PDU session, such as an identifier of the PDN connection or a PDU session identifier, and the like, which is not specifically limited in the embodiment of the present application.

And S417, the PGW-C network element and the SMF network element release corresponding PDN connection or PDU conversation.

The implementation of releasing the corresponding PDN connection or PDU session by the PGW-C network element and the SMF network element may refer to the existing procedure, and is not described herein again.

Optionally, in this embodiment of the present application, if the PDU session is already created in step S401 and a V-SMF network element exists on the PDU session path, the PGW-C network element + SMF network element further notifies the V-SMF network element to delete the session, which is not specifically limited in this embodiment of the present application.

If the session is a session in the home routing mode, the PGW-C network element + SMF network element in steps S415-S417 is the PGW-C network element + SMF network element of the terminal home location; if the session is a session in a non-home routing mode, the PGW-C network element + SMF network element in steps S415 to S417 is the PGW-C network element + SMF network element in the network where the terminal is currently located, and the description is unified here and will not be repeated.

It should be noted that steps S415-S417 show a specific implementation of PDN connection or PDU session release. Of course, in the embodiment of the present application, the PDN connection or the PDU session may also be released in other manners, for example, if the second AMF network element and the PDU session or the PGW-C network element + the SMF network element corresponding to the PDN connection are in the same network slice, the second AMF network element may directly notify the PGW-C network element + the SMF network element to release the corresponding PDN connection or the PDU session, which is not specifically limited in this embodiment of the present application.

It should be noted that, there is no inevitable execution sequence between steps S413-S414 and steps S415-S417 in the embodiment of the present application, and steps S413-S414 may be executed first, and then steps S415-S417 are executed; or steps S415-S417 may be executed first, and then steps S413-S414 may be executed; steps S413 to S414 and steps S415 to S417 may also be executed simultaneously, which is not specifically limited in this embodiment of the application.

It should be noted that, in the embodiment of the present application, the PGW-C network element + SMF network element in steps S407a-S413a, steps S407b-S408b, steps S407C-S409C, and steps 415-S417 may be different PGW-C network elements + SMF network elements, for simplicity, fig. 4 is only an exemplary illustration of one PGW-C network element + SMF network element, and this is not limited in the embodiment of the present application.

In the present application, the processing on the PDU session or PDN connection that is not successfully handed over is also applicable to the processing of the session in which the terminal moves from the 4G network to the 5G network in the idle mode. In idle mode, the difference from the embodiment of the present application is that: in the idle mode, the step S401 is not executed, and the first AMF network element obtains all session contexts corresponding to the terminal from the MME after receiving the step S402 according to the terminal identifier in the step S402. The method for the first AMF network element to obtain all session contexts corresponding to the terminal from the MME is the same as that in the prior art, and is not described herein again. Since step S401 is not performed, all PDN connections are not successfully switched in the idle mode, and therefore steps S407b-S408b are not performed in the idle mode.

Based on the session management method provided in the embodiment of the present application, in the session management method, the second AMF network element may obtain the identifier of the PDN connection and the S-NSSAI corresponding to the identifier of the PDN connection, and trigger the PGW-C network element + SMF network element to update the user plane path of the PDU session corresponding to the PDN connection according to the identifier of the PDN connection and the S-NSSAI corresponding to the identifier of the PDN connection, and the PGW-C network element + SMF network element may enable the IP address of the session not to change, that is, the target control plane function network element updates the user plane path of the PDU session corresponding to the PDN connection, so that interruption of the session may be avoided, and continuity of the service may be maintained. Therefore, based on the session management method, the continuity of the service can be maintained.

The actions of the second AMF network element in steps S401 to S417 may be executed by the processor 301 in the communication device 300 shown in fig. 3 by calling the application program code stored in the memory 303, which is not limited in this embodiment of the present invention.

Optionally, taking an architecture that the session management system described in fig. 2 is applied to the interworking between the 4G network and the 5G network shown in fig. 1-1 or fig. 1-2 as an example, as shown in fig. 5, another session management method provided in the embodiment of the present application is provided, where the session management method includes the following steps:

S501-S506 and synchronization steps S401-S406, the related description may refer to the embodiment shown in fig. 4, and will not be repeated herein.

Wherein, for the PDU session that has been successfully switched to the 5G network for the user plane path allowing updating the PDU session corresponding to the S-NSSAI, if the PDU session is in the home routing mode, the session management method further includes the following steps S507a-S512 a; for the PDU session that has been successfully switched to the 5G network for the user plane path allowing updating of the PDU session corresponding to the S-NSSAI, if the PDU session is in the non-home routing mode and does not need to select I-SMF, the session management method further includes the following steps S507b-S508 b; for the PDN connection or PDU session of the user plane path that does not allow updating of the PDU session corresponding to the S-NSSAI, the session management method further includes the following steps S525 to S527; for the unsuccessful handover of the user plane path allowing updating of the PDU session corresponding to the S-NSSAI to the PDN connection of the 5G network, the session management method further includes step S514 as follows.

S507a-S512a, and synchronization steps S407a-S412a, the related description may refer to the embodiment shown in FIG. 4, and will not be repeated herein.

S507b-S508b, and synchronization steps S407b-S413b, the related description can refer to the embodiment shown in FIG. 4, and will not be repeated herein.

And S513, the second AMF network element starts a timer with the timing duration being a preset duration.

If the timer is up, the second AMF network element still does not receive the PDU session establishment request corresponding to the PDN connection sent by the terminal, and the second AMF network element releases the PDN connection.

Further, the session management method further includes the following steps:

s514, the second AMF network element sends a registration response to the terminal, so that the terminal receives the registration response from the AMF network element.

Wherein the registration response carries the allowed NSSAI.

And S515, the terminal releases the corresponding PDN connection or PDU session according to the allowed NSSAI.

Illustratively, if the allowed NSSAI does not include the S-NSSAI, the terminal will release the corresponding PDN connection or PDU session.

Further, for a session that allows for an unsuccessful handover of the user plane path for updating the PDU session corresponding to the S-NSSAI to the 5G network, the session management method further includes the following steps:

s516, the terminal sends a PDU session establishment request to the second AMF network element, so that the second AMF network element receives the PDU session establishment request from the terminal.

The PDU session establishment request carries a PDU session identifier and is used for requesting establishment of a corresponding PDU session.

Further, if the session is in the home routing mode, the session management method provided in the embodiment of the present application further includes the following steps S517a-S522 a; if the session is a session in a non-home routing mode, the session management method provided in the embodiment of the present application further includes the following steps S517b-S519 b.

S517a-S522a, and synchronization steps S507a-S512a, the related description can refer to steps S507a-S512a, and the description is not repeated herein.

S517b-S519b, and synchronization steps S407c-S409c, the related description may refer to the embodiment shown in FIG. 4, and will not be repeated herein.

Further, after the PDU session is successfully established, the session management method provided in the embodiment of the present application further includes the following steps:

s523, the second AMF network element sends a PDU session setup response to the terminal, so that the terminal receives the PDU session setup response from the second AMF network element.

Optionally, in this embodiment of the present application, for the session in the home routing mode, the PDU session establishment response further needs to be sent to the terminal through the V-SMF network element, which is not specifically limited in this embodiment of the present application.

And S524, the second AMF network element determines that the timer expires.

PDN connections or PDU sessions for those user plane paths that do not allow updating of PDU sessions corresponding to S-NSSAI; or, for a PDN connection that allows an unsuccessful handover of a user plane path of a PDU session corresponding to an S-NSSAI to be updated, if a timer expires, the second AMF network element still does not receive a corresponding PDU session establishment request, the session management method provided in this embodiment of the present application further includes the following steps:

S525-S527 and synchronization steps S415-S417, the related description may refer to the embodiment shown in fig. 4, and will not be repeated herein.

Based on the session management method provided in the embodiment of the present application, in the session management method, the second AMF network element may obtain the identifier of the PDN connection and the S-NSSAI corresponding to the identifier of the PDN connection, and trigger the PGW-C network element + SMF network element to update the user plane path of the PDU session corresponding to the PDN connection according to the identifier of the PDN connection and the S-NSSAI corresponding to the identifier of the PDN connection, and the PGW-C network element + SMF network element may enable the IP address of the session not to change, that is, the target control plane function network element updates the user plane path of the PDU session corresponding to the PDN connection, so that interruption of the session may be avoided, and continuity of the service may be maintained. Therefore, based on the session management method, the continuity of the service can be maintained. In addition, the corresponding PDU session is established after the PDU session establishment request is received, so that the PDN connection which is actually switched is the PDN connection which the terminal wants to be switched and is allowed to be switched, and the user requirement can be better met.

The actions of the second AMF network element in steps S501 to S527 may be executed by the processor 301 in the communication device 300 shown in fig. 3 calling the application program code stored in the memory 303, which is not limited in this embodiment of the present invention.

Optionally, taking an architecture that the session management system described in fig. 2 is applied to the interworking between the 4G network and the 5G network shown in fig. 1 as an example, as shown in fig. 6, another session management method provided in the embodiment of the present application is provided, where the session management method includes the following steps:

S601-S615 are similar to steps S501-S515, except that in the registration request and the redirected registration request in this embodiment, the corresponding relationship between each S-NSSAI in the NSSAI carrying the terminal request and the identifier of the corresponding PDN connection may not be used, and the relevant description may refer to the embodiment shown in fig. 5, which is not described herein again.

S616, the terminal sends a PDU session setup request to the second AMF network element, so that the second AMF network element receives the PDU session setup request from the terminal.

In addition, the PDU session establishment request also carries a correspondence between the S-NSSAI corresponding to the requested PDU session and the identifier of the corresponding PDN connection, for the subsequent second AMF network element to associate the S-NSSAI with the PDN connection.

S617 to S627 and synchronization steps S517 to S527, and the related description may refer to the embodiment shown in fig. 5, which is not repeated herein.

Based on the session management method provided in the embodiment of the present application, continuity of the service can be maintained, and for the related analysis, reference may be made to the embodiment shown in fig. 5, which is not described herein again.

The actions of the second AMF network element in steps S601 to S627 may be executed by the processor 301 in the communication device 300 shown in fig. 3 by calling the application program code stored in the memory 303, which is not limited in this embodiment of the present application.

Optionally, when the session management system shown in fig. 2 is applied to the architecture in which the 4G network and the 5G network are intercommunicated as shown in fig. 1 to 3, the session management method provided in the embodiments corresponding to fig. 4, 5, and 6 may also be generated.

The difference with fig. 1-2 is that when applied to fig. 1-3, AMF chooses no more V-SMF but I-SMF, and V-SMF and PGW-C network element + SMF network element updates are no more user plane paths at visited place and between home and visited place, but user plane paths including intermediate UPF (I-UPF) and access device for terminal access (NG-RAN) and between I-UPF and anchor user plane network element (PGW-U network element + UPF network element). In addition, in the architectures shown in fig. 1-1 and fig. 1-3, the AMF needs to determine whether to select an I-SMF, for example, the AMF may query a Network Repository Function (Network redundancy Function, NRF) according to the UE location and the S-NSSAI, so as to obtain a candidate SMF list (any SMF in the candidate SMF list represents an SMF capable of providing a session service for the terminal), and if the PGW-C Network element + SMF Network element is not in the SMF list, the AMF selects an SMF from the list as the I-SMF; or the AMF queries an NRF according to the information (for example, FQDN) of the PGW-C network element and the SMF network element, the NRF sends the service area information of the PGW-C network element and the SMF network element to the AMF, and the AMF determines whether the PGW-C network element and the SMF network element can serve the current location of the UE according to the service area information of the PGW-C network element and the SMF network element, if not, the AMF selects the I-SMF according to the location of the UE and the S-NSSAI (the AMF may select the I-SMF according to the local configuration, or may select the I-SMF by querying the NRF).

In this embodiment, a visited SMF (i.e., V-SMF) is selected for a session in the home routing mode, and it should be noted that, when the session is in a Non-Roaming mode (Non-Roaming) or a Roaming Local routing mode (i.e., Roaming with Local Breakout), similar to the home routing mode, it may also be necessary to select an Intermediate SMF (I-SMF), and the process of selecting the Intermediate SMF is similar to the process of selecting the V-SMF in this embodiment, only the V-SMF in steps S407a-S413a in this embodiment needs to be replaced by an I-SMF network element, the V-UPF network element is replaced by an I-UPF network element (I-UPF, Intermediate UPF), and the "visited Local user plane path" is replaced by an "Intermediate user plane path" (I-UPF, an uplink tunnel between the I-UPF network element and an NG-RAN accessed by the UE, and a downlink tunnel between the I-UPF and the pgu network element + UPF), and replacing the user plane path from the visited place to the home place by the user plane path from the PGW-U network element + the UPF network element to the I-UPF network element.

The above-mentioned scheme provided by the embodiment of the present application is introduced mainly from the perspective of interaction between network elements. It will be understood that the above-described terminal and mobility management element, in order to implement the above-described functions, include corresponding hardware structures and/or software modules for performing the respective functions. Those of skill in the art would readily appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as hardware or combinations of hardware and computer software. Whether a function is performed as hardware or computer software drives hardware depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.

In the embodiment of the present application, the functional modules may be divided according to the above method example for the mobility management network element and the terminal, for example, each functional module may be divided corresponding to each function, or two or more functions may be integrated into one processing module. The integrated module can be realized in a hardware mode, and can also be realized in a software functional module mode. It should be noted that, in the embodiment of the present application, the division of the module is schematic, and is only one logic function division, and there may be another division manner in actual implementation.

For example, in the case of dividing the functional modules in an integrated manner, fig. 7 shows a schematic structural diagram of a mobility management network element 70. The mobility management element 70 comprises: a transceiver module 701 and a processing module 702. A transceiver module 701, configured to receive an identifier of a PDN connection from a terminal and an S-NSSAI corresponding to the identifier of the PDN connection; a processing module 702, configured to trigger a target control plane function network element to update a user plane path of a PDU session corresponding to a PDN connection according to the identifier of the PDN connection and the S-NSSAI.

Optionally, the processing module 702 is specifically configured to: under the condition that the PDN connection is in a home routing mode, selecting a target visited place session management network element for the PDU session according to S-NSSAI; acquiring information of a target control plane function network element according to the identifier of the PDN connection; and sending a first message to a target visited place session management network element, wherein the first message is used for indicating the target visited place session management network element to establish a visited place user plane path corresponding to the PDU session and triggering the target control plane function network element corresponding to the information of the target control plane function network element to update the user plane path between the visited place and the home place corresponding to the PDU session.

Further, the processing module 702 is further configured to determine that the target visited session management network element is different from the default visited session management network element in a case that the PDN connection is a PDN connection successfully switched to the 5G network in a process that the PDN connection is switched from the 4G network to the 5G network.

Optionally, the transceiver module 701 is further configured to send a third message to the user data management network element, where the third message is used for the mobility management network element to notify the target control plane function network element to release the PDN connection or the PDU session; or, the transceiver module 701 is further configured to send a fourth message to the target control plane function network element, where the fourth message is used for the target control plane function network element to release the PDN connection or the PDU session.

Optionally, the processing module 702 is further configured to acquire an allowed NSSAI, and determine to release the PDN connection or the PDU session when the allowed NSSAI does not include the S-NSSAI.

Further, the processing module 702 is further configured to determine a user plane path allowing updating of the PDU session if the allowed NSSAI includes S-NSSAI.

Optionally, the transceiver module 701 is configured to receive an identifier of the PDN connection and an S-NSSAI corresponding to the identifier of the PDN connection, and includes configured to receive a registration request from the terminal, where the registration request carries the identifier of the PDN connection and the S-NSSAI.

Or, optionally, the transceiver module 701 is configured to receive an identifier of the PDN connection and an S-NSSAI corresponding to the identifier of the PDN connection, and includes a component configured to receive a session establishment request from the terminal, where the session establishment request carries the identifier of the PDN connection and the S-NSSAI.

Optionally, the transceiver module 701 is further configured to receive a registration request from a terminal; the transceiver module 701 is further configured to send a registration response to the terminal, where the registration response carries an allowed NSSAI, and the allowed NSSAI includes an S-NSSAI; the processing module 702 is further configured to, when the PDN connection is a PDN connection that is not successfully switched to the 5G network in a process of switching the terminal from the 4G network to the 5G network, determine to release the PDN connection if the sending module 701 does not receive the session establishment request from the terminal within a preset time duration.

All relevant contents of each step related to the above method embodiment may be referred to the functional description of the corresponding functional module, and are not described herein again.

In the embodiment of the present application, the mobility management element 70 is presented in a form of dividing each functional module in an integrated manner. A "module" herein may refer to a particular ASIC, a circuit, a processor and memory that execute one or more software or firmware programs, an integrated logic circuit, and/or other device that provides the described functionality. In a simple embodiment, it will be appreciated by those skilled in the art that the mobility management element 70 may take the form shown in fig. 3.

For example, the processor 301 in fig. 3 may cause the mobility management element 70 to execute the session management method in the above-described method embodiment by calling a computer stored in the memory 303 to execute the instructions.

In particular, the functions/implementation procedures of the transceiver module 701 and the processing module 702 in fig. 7 may be implemented by the processor 301 in fig. 3 calling a computer executing instructions stored in the memory 303. Alternatively, the function/implementation procedure of the processing module 702 in fig. 7 may be implemented by the processor 301 in fig. 3 calling a computer executing instruction stored in the memory 303, and the function/implementation procedure of the transceiver module 701 in fig. 7 may be implemented by the communication interface 303 in fig. 3.

Since the mobility management element provided in the embodiment of the present application can execute the session management method, the technical effect obtained by the mobility management element can refer to the method embodiment described above, and is not described herein again.

Optionally, an embodiment of the present application provides a chip system, where the chip system includes a processor, and is configured to support a mobility management network element to implement the session management method, for example, according to an identifier of a PDN connection and an S-NSSAI, trigger a target control plane function network element to update a user plane path of a PDU session corresponding to the PDN connection. In one possible design, the system-on-chip further includes a memory. The memory is used for storing program instructions and data necessary for the mobility management element. Of course, the memory may not be in the system-on-chip. The chip system may be formed by a chip, and may also include a chip and other discrete devices, which is not specifically limited in this embodiment of the present application.

For example, in the case of dividing each functional module in an integrated manner, fig. 8 shows a schematic structural diagram of an apparatus 80. The device 80 may be a terminal in the above embodiment, or may be a chip or a circuit in the terminal in the above embodiment, which is not specifically limited in this embodiment. Wherein the device 80 comprises: a receiving module 801 and a sending module 802. A receiving module 801, configured to receive an identifier of a PDN connection and an S-NSSAI corresponding to the identifier of the PDN connection; a sending module 802, configured to send an identifier of a PDN connection and an S-NSSAI to a mobility management network element, where the identifier of the PDN connection and the S-NSSAI are used to trigger a target control plane function network element to update a user plane path of a PDU session corresponding to the PDN connection.

In a possible implementation manner, the sending module 802 is specifically configured to: and sending a registration request to a mobile management network element, wherein the registration request carries the identification of the PDN connection and the S-NSSAI.

Further, as shown in fig. 8, the apparatus 80 further includes: a processing module 803. A receiving module 801, configured to receive a registration response from a mobility management element, where the registration response carries an allowed NSSAI; a processing module 803 for releasing the PDN connection if the allowed NSSAI does not include S-NSSAI.

Further, the sending module 802 is further configured to send a session establishment request to the mobility management network element, where the session establishment request carries an identifier of a PDU session and is used to request to establish the PDU session, when the PDN connection is a PDN connection that is not successfully switched to the 5G network in a process of switching the terminal from the 4G network to the 5G network and an allowed NSSAI includes an S-NSSAI.

Optionally, the receiving module 801 is further configured to receive a registration response from the mobility management element, where the registration response carries a session state, and the session state includes information indicating that the terminal releases the PDN connection or the PDU session release; a processing module 803, configured to release the PDN connection or the PDU session according to the session status.

In another possible implementation manner, the sending module 802 is specifically configured to: and sending a session establishment request to a mobile management network element, wherein the session establishment request carries the identification of the PDN connection and the S-NSSAI.

Optionally, the sending module 802 is further configured to send a registration request to the mobility management element; a receiving module 801, further configured to receive a registration response from the mobility management element, where the registration response carries an allowed NSSAI; the sending module 802 is configured to send a session establishment request to a mobility management element, and includes: and sending a session establishment request to the mobility management network element in the case that the PDN connection is the PDN connection which is not successfully switched to the 5G network in the process of switching the terminal from the 4G network to the 5G network and the allowed NSSAI comprises S-NSSAI.

Optionally, as shown in fig. 8, the apparatus 80 further includes: a processing module 803; a processing module 803 for releasing the PDN connection if the allowed NSSAI does not include S-NSSAI.

In the present embodiment, the apparatus 80 is presented in the form of dividing each functional module in an integrated manner. A "module" herein may refer to a particular ASIC, a circuit, a processor and memory that execute one or more software or firmware programs, an integrated logic circuit, and/or other device that provides the described functionality.

In a simple embodiment, those skilled in the art will appreciate that the apparatus 80 may take the form shown in FIG. 3.

For example, the processor 301 in fig. 3 may execute the instructions by calling a computer stored in the memory 303, so that the apparatus 80 executes the session establishment method in the above method embodiment.

In particular, the functions/implementation procedures of the receiving module 801, the sending module 802 and the processing module 803 in fig. 8 can be implemented by the processor 301 in fig. 3 calling a computer executing instructions stored in the memory 303. Alternatively, the function/implementation procedure of the processing module 803 in fig. 8 may be implemented by the processor 301 in fig. 3 calling a computer executing instruction stored in the memory 303, and the function/implementation procedures of the receiving module 801 and the sending module 802 in fig. 8 may be implemented by the communication interface 303 in fig. 3.

Alternatively, when the apparatus 80 is a chip or a circuit, the functions/implementation procedures of the receiving module 801 and the sending module 802 can also be implemented by pins or circuits. Alternatively, when the apparatus 80 is a chip or a circuit, the memory 303 may be a storage unit in the chip or the circuit, such as a register, a cache, and the like. Of course, when the apparatus 80 is a terminal, the memory 303 may be a storage unit located outside the chip in the terminal, and this embodiment of the present application is not particularly limited thereto.

Since the apparatus provided in the embodiment of the present application can be used to execute the session management method, the technical effect obtained by the apparatus can refer to the method embodiment, and will not be described herein again.

In the above embodiments, the implementation may be wholly or partially realized by software, hardware, firmware, or any combination thereof. When implemented using a software program, may be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. The procedures or functions described in accordance with the embodiments of the present application are all or partially generated upon loading and execution of computer program instructions on a computer. The computer may be a general purpose computer, a special purpose computer, a network of computers, or other programmable device. The computer instructions may be stored on a computer readable storage medium or transmitted from one computer readable storage medium to another, for example, from one website, computer, server, or data center to another website, computer, server, or data center via wire (e.g., coaxial cable, fiber optic, Digital Subscriber Line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium that can be accessed by a computer or can comprise one or more data storage devices, such as a server, a data center, etc., that can be integrated with the medium. The usable medium may be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., Solid State Disk (SSD)), among others.

While the present application has been described in connection with various embodiments, other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed application, from a review of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the word "a" or "an" does not exclude a plurality. A single processor or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Although the present application has been described in conjunction with specific features and embodiments thereof, it will be evident that various modifications and combinations can be made thereto without departing from the spirit and scope of the application. Accordingly, the specification and figures are merely exemplary of the present application as defined in the appended claims and are intended to cover any and all modifications, variations, combinations, or equivalents within the scope of the present application. 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 management, the method comprising:

a mobile management network element receives an identifier of a Packet Data Network (PDN) connection from a terminal and single network slice selection auxiliary information S-NSSAI corresponding to the identifier of the PDN connection;

and under the condition that the terminal is successfully switched to a fifth generation 5G network from a fourth generation 4G network, when the PDN connection is in a home routing mode, and the mobile management network element determines that a target visited place session management network element is different from a default visited place session management network element, or when the mobile management network element determines that an intermediate session management network element is different from the default session management network element, the mobile management network element triggers a target control plane function network element to update a user plane path of a packet data unit PDU session corresponding to the PDN connection according to the identifier of the PDN connection and the S-NSSAI.

2. The method of claim 1, wherein the triggering, by the mobility management element, a target control plane function element to update a user plane path of a PDU session corresponding to the PDN connection according to the identity of the PDN connection and the S-NSSAI comprises:

the mobile management network element acquires information of a target control plane function network element according to the identifier of the PDN connection;

and the mobile management network element sends a first message to the target visited place session management network element, wherein the first message is used for indicating the target visited place session management network element to establish a visited place user plane path corresponding to the PDU session and triggering the target control plane function network element corresponding to the information of the target control plane function network element to update the user plane path between the visited place and the home place corresponding to the PDU session.

3. The method of claim 1, wherein the triggering, by the mobility management element, a target control plane function element to update a user plane path of a PDU session corresponding to the PDN connection according to the identity of the PDN connection and the S-NSSAI comprises:

and the mobility management network element sends a first message to the intermediate session management network element, where the first message is used to instruct the intermediate session management network element to establish an intermediate user plane path corresponding to the PDU session, and to trigger a target control plane function network element corresponding to the information of the target control plane function network element to update a user plane path from an anchor user plane network element corresponding to the PDU session to the intermediate user plane network element.

4. A method according to any of claims 1-3, wherein when the PDN connection is in a home routing mode, before the mobility management element determines that the target visited session management element and the default visited session management element are different, or before the mobility management element determines that the intermediate session management element and the default session management element are different, the method further comprises:

and the mobile management network element selects the target visited place session management network element or the intermediate session management network element for the PDU session according to the S-NSSAI.

5. The method according to any one of claims 1-3, further comprising:

the mobility management network element sends a third message to a user data management network element, where the third message is used for the mobility management network element to notify the target control plane function network element to release the PDN connection or the PDU session;

or, the mobility management network element sends a fourth message to the target control plane function network element, where the fourth message is used for the target control plane function network element to release the PDN connection or the PDU session.

6. The method according to any one of claims 1-3, further comprising:

the mobile management network element acquires allowed network slice selection auxiliary information NSSAI;

in the case that the S-NSSAI is not included in the allowed NSSAI, the mobility management network element determines to release the PDN connection or the PDU session.

7. The method of claim 6, wherein before the mobility management element triggers a target control plane function element to update a user plane path of a PDU session corresponding to the PDN connection, the method further comprises:

in case the S-NSSAI is included in the allowed NSSAI, the mobility management element determines a user plane path that allows updating of the PDU session.

8. The method of any of claims 1-3, wherein the receiving, by the mobility management network element, the identity of the PDN connection and the S-NSSAI corresponding to the identity of the PDN connection comprises:

and the mobile management network element receives a registration request from a terminal, wherein the registration request carries the identifier of the PDN connection and the S-NSSAI.

9. The method of any of claims 1-3, wherein the receiving, by the mobility management network element, the identity of the PDN connection and the S-NSSAI corresponding to the identity of the PDN connection comprises:

and the mobile management network element receives a session establishment request from a terminal, wherein the session establishment request carries the identifier of the PDN connection and the S-NSSAI.

10. The method of claim 9, further comprising:

the mobile management network element receives a registration request from a terminal;

the mobile management network element sends a registration response to the terminal, wherein the registration response carries an allowed NSSAI, and the allowed NSSAI comprises the S-NSSAI;

and if the PDN connection is the PDN connection which is not successfully switched to the 5G network in the process of switching the terminal from the 4G network to the 5G network, the mobile management network element determines to release the PDN connection if the mobile management network element does not receive the session establishment request from the terminal within a preset time length.

11. The method according to any one of claims 1-3, further comprising:

the mobile management network element receives indication information, wherein the indication information is used for indicating that the PDN connection is the PDN connection which is not successfully switched to the 5G network in the process that the terminal is switched from the 4G network to the 5G network; or the indication information is used for indicating that the PDN connection is a PDN connection successfully switched to the 5G network in the process of switching the terminal from the 4G network to the 5G network.

12. A method for session management, the method comprising:

a terminal receives an identifier of a Packet Data Network (PDN) connection and single network slice selection auxiliary information S-NSSAI corresponding to the identifier of the PDN connection;

the terminal sends the identifier of the PDN connection and the S-NSSAI to a mobile management network element;

when the terminal is successfully switched from the fourth generation 4G network to the fifth generation 5G network, when the PDN connection is in a home routing mode, and the mobility management element determines that the target visited session management element is different from the default visited session management element, or when the mobility management element determines that the intermediate session management element is different from the default session management element, the identifier of the PDN connection and the S-NSSAI are used to trigger the target control plane function element to update the user plane path of the packet data unit PDU session corresponding to the PDN connection.

13. The method of claim 12, wherein the terminal sends an identifier of a PDN connection and an S-NSSAI corresponding to the identifier of the PDN connection to a mobility management network element, and wherein the step of sending the identifier of the PDN connection to the mobility management network element comprises:

and the terminal sends a registration request to the mobile management network element, wherein the registration request carries the identifier of the PDN connection and the S-NSSAI.

14. The method of claim 13, further comprising:

the terminal receives a registration response from the mobile management network element, wherein the registration response carries an allowed NSSAI;

in the event that the allowed NSSAI does not include the S-NSSAI, the terminal releases the PDN connection.

15. The method of claim 14, further comprising:

and under the condition that the PDN connection is not successfully switched to the PDN connection of the 5G network in the process that the terminal is switched from the 4G network to the 5G network, and the allowed NSSAI comprises the S-NSSAI, the terminal sends a session establishment request to the mobility management network element, wherein the session establishment request carries the PDU session identifier and is used for requesting to establish the PDU session.

16. The method of claim 13, further comprising:

the terminal receives a registration response from the mobile management network element, wherein the registration response carries a session state, and the session state comprises information indicating that the terminal releases the PDN connection or the PDU session release;

and the terminal releases the PDN connection or the PDU session according to the session state.

17. The method of claim 12, wherein the terminal sends an identifier of a PDN connection and an S-NSSAI corresponding to the identifier of the PDN connection to a mobility management network element, and wherein the step of sending the identifier of the PDN connection to the mobility management network element comprises:

and the terminal sends a session establishment request to the mobile management network element, wherein the session establishment request carries the identifier of the PDN connection and the S-NSSAI.

18. The method of claim 17, before the terminal sends the session establishment request to the mobility management element, further comprising:

the terminal sends a registration request to the mobile management network element;

the terminal sends a session establishment request to the mobility management network element, including:

and in the case that the PDN connection is a PDN connection that the terminal is not successfully handed over to the 5G network in the process of handing over from the 4G network to the 5G network, and the allowed NSSAI includes the S-NSSAI, the terminal sends the session establishment request to the mobility management network element.

19. The method of claim 18, further comprising:

20. A mobility management element, wherein the mobility management element comprises: a transceiver module and a processing module;

the receiving and sending module is used for receiving an identifier of a Packet Data Network (PDN) connection from a terminal and single network slice selection auxiliary information S-NSSAI corresponding to the identifier of the PDN connection;

and under the condition that the terminal is successfully switched from the fourth generation 4G network to the fifth generation 5G network, when the PDN connection is in a home routing mode, and the processing module determines that a target visited place session management network element is different from a default visited place session management network element, or determines that an intermediate session management network element is different from the default session management network element, the processing module is configured to trigger a target control plane function network element to update a user plane path of a Packet Data Unit (PDU) session corresponding to the PDN connection according to the identifier of the PDN connection and the S-NSSAI.

21. The mobility management element according to claim 20, wherein the processing module is specifically configured to:

acquiring information of a target control plane function network element according to the identifier of the PDN connection; and sending a first message to the target visited place session management network element, wherein the first message is used for indicating the target visited place session management network element to establish a visited place user plane path corresponding to the PDU session, and triggering the target control plane function network element corresponding to the information of the target control plane function network element to update the user plane path between the visited place and the home place corresponding to the PDU session.

22. The mobility management element according to claim 20, wherein the processing module is specifically configured to:

acquiring information of a target control plane function network element according to the identifier of the PDN connection; and sending a first message to the intermediate session management network element, where the first message is used to instruct the intermediate session management network element to establish an intermediate user plane path corresponding to the PDU session, and to trigger a target control plane function network element corresponding to the information of the target control plane function network element to update a user plane path from an anchor user plane network element corresponding to the PDU session to the intermediate user plane network element.

23. Mobility management network element according to any of claims 20-22,

the processing module is further configured to select the target visited session management network element or the intermediate session management network element for the PDU session according to the S-NSSAI.

24. Mobility management network element according to any of claims 20-22,

the transceiver module is further configured to send a third message to a user data management network element, where the third message is used for the mobility management network element to notify the target control plane function network element to release the PDN connection or the PDU session;

or, the transceiver module is further configured to send a fourth message to the target control plane function network element, where the fourth message is used for the target control plane function network element to release the PDN connection or the PDU session.

25. Mobility management network element according to any of claims 20-22,

the processing module is further configured to acquire allowed network slice selection auxiliary information NSSAI;

the processing module is further configured to determine to release the PDN connection or the PDU session if the S-NSSAI is not included in the allowed NSSAI.

26. The mobility management network element according to claim 25,

the processing module is further configured to determine a user plane path allowing updating of the PDU session if the S-NSSAI is included in the allowed NSSAI.

27. The mobility management network element according to any of claims 20-22, wherein the transceiver module is configured to receive an identity of a PDN connection and an S-NSSAI corresponding to the identity of the PDN connection, and comprises:

and the terminal is used for receiving a registration request from the terminal, wherein the registration request carries the identifier of the PDN connection and the S-NSSAI.

28. The mobility management network element according to any of claims 20-22, wherein the transceiver module is configured to receive an identity of a PDN connection and an S-NSSAI corresponding to the identity of the PDN connection, and comprises:

and the session establishment request is used for receiving a session establishment request from a terminal, and the session establishment request carries the identifier of the PDN connection and the S-NSSAI.

29. The mobility management network element according to claim 28,

the transceiver module is also used for receiving a registration request from a terminal;

the transceiver module is further configured to send a registration response to the terminal, where the registration response carries an allowed NSSAI, and the allowed NSSAI includes the S-NSSAI;

the processing module is further configured to, when the PDN connection is a PDN connection that is not successfully switched to the 5G network in a process in which the terminal is switched from the 4G network to the 5G network, determine to release the PDN connection if the transceiver module does not receive the session establishment request from the terminal within a preset time period.

30. A terminal, characterized in that the terminal comprises: the device comprises a receiving module and a sending module;

the receiving module is used for receiving an identifier of a Packet Data Network (PDN) connection and single network slice selection auxiliary information S-NSSAI corresponding to the identifier of the PDN connection;

the sending module is configured to send the identifier of the PDN connection and the S-NSSAI to a mobility management network element;

31. The terminal of claim 30, wherein the sending module is specifically configured to:

and sending a registration request to the mobile management network element, wherein the registration request carries the identifier of the PDN connection and the S-NSSAI.

32. The terminal of claim 31, wherein the terminal further comprises: a processing module;

the receiving module is configured to receive a registration response from the mobility management element, where the registration response carries an allowed NSSAI;

the processing module is configured to release the PDN connection if the allowed NSSAI does not include the S-NSSAI.

33. The terminal of claim 32,

the sending module is further configured to send a session establishment request to the mobility management network element, where the session establishment request carries an identifier of the PDU session, and is used to request establishment of the PDU session, when the PDN connection is a PDN connection that is not successfully switched to the 5G network in a process in which the terminal is switched from the 4G network to the 5G network, and the allowed NSSAI includes the S-NSSAI.

34. The terminal of claim 31, wherein the terminal further comprises: a processing module;

the receiving module is further configured to receive a registration response from the mobility management network element, where the registration response carries a session state, and the session state includes information indicating that the terminal releases the PDN connection or the PDU session release;

and the processing module is used for releasing the PDN connection or the PDU session according to the session state.

35. The terminal of claim 30, wherein the sending module is specifically configured to:

and sending a session establishment request to the mobile management network element, wherein the session establishment request carries the identifier of the PDN connection and the S-NSSAI.

36. The terminal of claim 35,

the sending module is further configured to send a registration request to the mobility management network element;

the receiving module is further configured to receive a registration response from the mobility management element, where the registration response carries an allowed NSSAI;

the sending module is configured to send a session establishment request to the mobility management element, and includes:

and sending the session establishment request to the mobility management network element if the PDN connection is a PDN connection that the terminal has not successfully handed over to a 5G network in a handover procedure of the terminal from the 4G network to the 5G network and if the allowed NSSAI includes the S-NSSAI.

37. The terminal of claim 36, wherein the terminal further comprises: a processing module;

38. A session management system, comprising a mobility management element and a target control plane function element;

the mobile management network element is used for receiving an identifier of a Packet Data Network (PDN) connection from a terminal and single network slice selection auxiliary information S-NSSAI corresponding to the identifier of the PDN connection;

the mobility management element is further configured to, when the PDN connection is in a home routing mode and the mobility management element determines that the target visited session management element is different from the default visited session management element, or when the mobility management element determines that the intermediate session management element is different from the default session management element, trigger the target control plane functional element to update the user plane path of the packet data unit PDU session corresponding to the PDN connection according to the identifier of the PDN connection and the S-NSSAI when the terminal is successfully switched from the fourth-generation 4G network to the fifth-generation 5G network;

and the target control plane functional network element is used for updating a user plane path of the PDU session corresponding to the PDN connection.