CN110856273A

CN110856273A - Session management method, device and system

Info

Publication number: CN110856273A
Application number: CN201810950774.9A
Authority: CN
Inventors: 景昊; 宗在峰; 朱奋勤
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2018-08-20
Filing date: 2018-08-20
Publication date: 2020-02-28
Anticipated expiration: 2038-08-20
Also published as: CN110856273B

Abstract

The embodiment of the application provides a session management method, a device and a system, so that corresponding PDN connection can be still established under the condition that a plurality of anchor point session management network elements corresponding to a plurality of different PDU sessions with the same DNN exist in a mobile management network element. The session management method comprises the following steps: the method comprises the steps that a mobile management network element receives a request message from a terminal, wherein the request message comprises a switching instruction, and the switching instruction is used for instructing to switch a first Packet Data Unit (PDU) session corresponding to a first Data Network Name (DNN) into a first Packet Data Network (PDN) connection corresponding to a first Access Point Name (APN); and the mobility management network element determines the information of the first anchor point session management network element in the information of the anchor point session management network elements corresponding to the first DNN as the information of the anchor point session management network element corresponding to the first PDN connection according to the request message.

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

Under the existing scenario that a fourth generation (4th generation, 4G) network and a fifth generation (5th generation, 5G) network are intercommunicated, a terminal may have multiple packet session units (PDU) sessions in the 5G network, which have the same Data Network Name (DNN) but correspond to different single network slice selection auxiliary information (S-NSSAI), that is, the multiple PDU sessions are served by different Session Management Functions (SMF) in different network slices identified by the S-NSSAI + network element (packet data, PDN) gateway control plane function (pdnway control function, PGW-C) network elements; in the 4G network, different PDN connections of the terminal corresponding to the same Access Point Name (APN) can only be served by one SMF network element + PGW-C network element.

However, when the terminal moves from the 5G network to the 4G network, information of multiple SMF network elements + PGW-C network elements corresponding to different PDU sessions with the same DNN may exist in a Mobility Management Entity (MME), and how to establish the PDN connection is an urgent problem at present.

Disclosure of Invention

The embodiment of the application provides a session management method, a device and a system, so that corresponding PDN connection can be still established under the condition that a plurality of anchor point session management network elements corresponding to a plurality of different PDU sessions with the same DNN exist in a mobile management network element.

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 session management method includes: the method comprises the steps that a mobile management network element receives a request message from a terminal, wherein the request message comprises a switching instruction, and the switching instruction is used for instructing to switch a first Packet Data Unit (PDU) session corresponding to a first Data Network Name (DNN) into a first Packet Data Network (PDN) connection corresponding to a first Access Point Name (APN); and the mobility management network element determines the information of the first anchor point session management network element in the information of the anchor point session management network elements corresponding to the first DNN as the information of the anchor point session management network element corresponding to the first PDN connection according to the request message. Based on the scheme, after receiving the request message from the terminal, the mobility management network element determines, as the information of the anchor session management network element corresponding to the first PDN connection, the information of the first anchor session management network element in the information of the anchor session management network elements corresponding to the first DNN, so that the corresponding PDN connection is established when a plurality of anchor session management network elements corresponding to different PDU sessions having the same DNN exist in the mobility management network element.

In one possible design, the determining, by the mobility management network element, information of a first anchor session management network element in the information of the anchor session management network elements corresponding to the first DNN as information of an anchor session management network element corresponding to the first PDN connection according to the request message includes: and the mobile management network element determines the information of the first anchor point session management network element in the information of the anchor point session management network elements corresponding to the first DNN as the information of the anchor point session management network element corresponding to the first PDN according to the request message and the information of the existing PDN connection. That is to say, in the embodiment of the present application, the mobility management network element may determine, by combining information of an existing PDN connection, information of an anchor point session management network element corresponding to a first PDN connection that needs to be established, so that a corresponding PDN connection may be successfully established.

In one possible design, the determining, by the mobility management network element, the information of the first anchor session management network element in the information of the anchor session management network elements corresponding to the first DNN as the information of the anchor session management network element corresponding to the first PDN connection according to the request message and the information of the existing PDN connection includes: and when the existing PDN connection information comprises the PDN connection information corresponding to the first APN, the mobile management network element determines the information of the anchor point session management network element in the PDN connection information corresponding to the first APN as the information of the anchor point session management network element corresponding to the first PDN connection according to the request message. That is to say, in this embodiment of the application, when the existing PDN connection information includes the PDN connection information corresponding to the first APN, the mobility management network element may determine, as the information mobility management network element of the anchor point session management network element corresponding to the first PDN connection, the information of the anchor point session management network element in the PDN connection information corresponding to the first APN, so as to meet a requirement that different PDN connections of a terminal corresponding to the same APN in a network can only be served by one anchor point session management network element, and thus, the corresponding PDN connection may be successfully established.

In one possible design, the determining, by the mobility management network element, the information of the first anchor session management network element in the information of the anchor session management network elements corresponding to the first DNN as the information of the anchor session management network element corresponding to the first PDN connection according to the request message and the information of the existing PDN connection includes: and when the information of the PDN connection does not include the information of the PDN connection corresponding to the first APN, the mobility management network element determines, according to the request message and subscription data of the terminal, information of a first anchor session management network element in the information of the anchor session management network elements corresponding to the first DNN as the information of the anchor session management network element corresponding to the first PDN connection, where the subscription data includes the information of the anchor session management network elements corresponding to the first DNN. That is to say, in this embodiment of the application, when the information of the existing PDN connection does not include the information of the PDN connection corresponding to the first APN, the mobility management network element may determine, according to the subscription data of the terminal, the information of the first anchor session management network element in the information of the multiple anchor session management network elements corresponding to the first DNN as the information of the anchor session management network element corresponding to the first PDN connection, so that the corresponding PDN connection may be successfully established.

In one possible design, the determining, by the mobility management network element, information of a first anchor session management network element in the information of the anchor session management network elements corresponding to the first DNN as information of an anchor session management network element corresponding to the first PDN connection according to the request message includes: and the mobility management network element determines, according to the request message and subscription data of the terminal, information of a first anchor session management network element in the information of the anchor session management network elements corresponding to the first DNN as information of an anchor session management network element corresponding to the first PDN connection, where the subscription data includes information of the anchor session management network elements corresponding to the first DNN. That is to say, in the embodiment of the present application, the mobility management network element may determine, by combining subscription data of the terminal, information of an anchor point session management network element corresponding to the first PDN connection that needs to be established, so that the corresponding PDN connection may be successfully established.

In a second aspect, a session management method is provided, and the session management method includes: the method comprises the steps that a mobile management network element receives an access request from a terminal, and the mobile management network element determines information of a first anchor point session management network element in information of a plurality of anchor point session management network elements corresponding to a first DNN as the information of the anchor point session management network element corresponding to the first PDN, wherein a first access point name APN corresponding to the first PDN is the APN corresponding to the first DNN. Based on the scheme, after receiving the access request from the terminal, the mobility management network element determines, as the information of the anchor session management network element corresponding to the first PDN connection, the information of the first anchor session management network element in the information of the anchor session management network elements corresponding to the first DNN, so that the corresponding PDN connection is established when a plurality of anchor session management network elements corresponding to different PDU sessions having the same DNN exist in the mobility management network element.

In one possible design, the determining, by the mobility management network element according to the access request, information of a first anchor session management network element in information of multiple anchor session management network elements corresponding to the first DNN as information of an anchor session management network element corresponding to the first PDN connection includes: and the mobility management network element determines the information of the first anchor point session management network element in the information of the anchor point session management network elements corresponding to the first DNN as the information of the anchor point session management network element corresponding to the first PDN according to the access request and the information of the existing PDN connection. That is to say, in the embodiment of the present application, the mobility management network element may determine, by combining information of an existing PDN connection, information of an anchor point session management network element corresponding to a first PDN connection that needs to be established, so that a corresponding PDN connection may be successfully established.

In one possible design, the determining, by the mobility management network element, information of a first anchor session management network element in the information of the anchor session management network elements corresponding to the first DNN as information of an anchor session management network element corresponding to the first PDN connection according to the access request and information of an existing PDN connection includes: and when the existing PDN connection information comprises the PDN connection information corresponding to the first APN, the mobility management network element determines the anchor point session management network element information in the PDN connection information corresponding to the first APN as the anchor point session management network element information corresponding to the first PDN connection according to the access request. That is to say, in this embodiment of the application, when the existing PDN connection information includes the PDN connection information corresponding to the first APN, the mobility management network element may determine, as the information mobility management network element of the anchor point session management network element corresponding to the first PDN connection, the information of the anchor point session management network element in the PDN connection information corresponding to the first APN, so as to meet a requirement that different PDN connections of a terminal corresponding to the same APN in a network can only be served by one anchor point session management network element, and thus, the corresponding PDN connection may be successfully established.

In one possible design, the determining, by the mobility management network element, information of a first anchor session management network element in the information of the anchor session management network elements corresponding to the first DNN as information of an anchor session management network element corresponding to the first PDN connection according to the access request and information of an existing PDN connection includes: and when the information of the PDN connection does not include the information of the PDN connection corresponding to the first APN, the mobility management network element determines, according to the access request and subscription data of the terminal, information of a first anchor session management network element in the information of the anchor session management network elements corresponding to the first DNN as the information of the anchor session management network element corresponding to the first PDN connection, where the subscription data includes the information of the anchor session management network elements corresponding to the first DNN. That is to say, in this embodiment of the application, when the information of the existing PDN connection does not include the information of the PDN connection corresponding to the first APN, the mobility management network element may determine, according to the subscription data of the terminal, the information of the first anchor session management network element in the information of the multiple anchor session management network elements corresponding to the first DNN as the information of the anchor session management network element corresponding to the first PDN connection, so that the corresponding PDN connection may be successfully established.

In one possible design, the determining, by the mobility management network element according to the access request, information of a first anchor session management network element in the information of the anchor session management network elements corresponding to the first DNN as information of an anchor session management network element corresponding to the first PDN connection includes: and the mobility management network element determines, according to the access request and subscription data of the terminal, information of a first anchor session management network element in information of a plurality of anchor session management network elements corresponding to the first DNN as information of an anchor session management network element corresponding to the first PDN connection, where the subscription data includes information of the plurality of anchor session management network elements corresponding to the first DNN. That is to say, in the embodiment of the present application, the mobility management network element may determine, by combining subscription data of the terminal, information of an anchor point session management network element corresponding to the first PDN connection that needs to be established, so that the corresponding PDN connection may be successfully established.

With reference to the first aspect or the second aspect, in a possible design, after the mobility management network element determines, as the information of the anchor session management network element corresponding to the first PDN connection, information of a first anchor session management network element in information of multiple anchor session management network elements corresponding to the first DNN, the session management method further includes: the mobility management network element deletes, from the information of the anchor session management network elements corresponding to the first DNN, information of the anchor session management network elements other than the information of the first anchor session management network element. That is to say, in this embodiment of the application, the mobility management network element may further process redundant information in the information of the multi-anchor session management network element corresponding to the first DNN, for example, delete the redundant information, so that when the subsequent terminal initiates a PDN connection establishment procedure carrying the first APN, the mobility management network element may not select these anchor session management network elements, and it is ensured that different PDN connections of the terminal corresponding to the same APN can only be served by one anchor session management network element, thereby avoiding a problem of handover failure that may be caused. In addition, the redundant information is deleted, so that the storage space of the mobile management network element can be saved.

With reference to the first aspect or the second aspect, in a possible design, after the mobility management network element determines, as the information of the anchor session management network element corresponding to the first PDN connection, information of a first anchor session management network element in information of multiple anchor session management network elements corresponding to the first DNN, the session management method further includes: the mobility management network element marks the information of the anchor session management network elements except the information of the first anchor session management network element in the information of the anchor session management network elements corresponding to the first DNN as unavailable; or, the mobility management network element marks, as available, the information of the first anchor session management network element in the information of the anchor session management network elements corresponding to the first DNN. That is to say, in this embodiment of the application, the MME may further process redundant information in the information of the multiple anchor point session management network elements corresponding to the first DNN, for example, mark the redundant information, so that when the subsequent terminal initiates a PDN connection establishment procedure carrying the first APN, the mobility management network element may not select the anchor point session management network elements, and it is ensured that different PDN connections of the terminal corresponding to the same APN can only be served by one anchor point session management network element, thereby avoiding a problem of handover failure that may be caused.

With reference to the first aspect or the second aspect, in a possible design, the session management method further includes: the mobility management network element sends indication information to a user data management network element, wherein the indication information is used for indicating the information of the first anchor point session management network element selected by the mobility management network element. Therefore, after the user data network element obtains the information of the first anchor point session management network element selected by the mobility management network element, the user data network element can indicate the information of the first anchor point session management network element to the AAA server, so that the problem that the selection of the SMF network element + PGW-C network element is different from that selected by the 3GPP side of the 4G network when the terminal is switched to the non-3GPP side of the 4G network can be avoided, the different PDN connections of the terminal corresponding to the same APN can be ensured to be served only by one SMF network element + PGW-C network element, and the problem of possible switching failure is avoided.

In a third aspect, a mobility management network element is provided, where the mobility management network element has a function of implementing the method of any one of the first aspect or 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 fourth aspect, a mobility management network element is provided, comprising: a processor and a memory; the memory is configured to store computer-executable instructions, and when the mobility management element is running, the processor executes the computer-executable instructions stored by the memory to cause the mobility management element to perform the session management method according to any one of the first aspect or the second aspect.

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

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 first or second 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 one of the first or second aspects.

In an eighth aspect, an apparatus (e.g., the apparatus may be a system-on-chip) is provided that includes a processor configured to enable a mobility management network element to implement the functions recited in the first or second aspects, for example, determine, according to a request message, information of a first anchor session management network element in information of a plurality of anchor session management network elements corresponding to a first DNN as information of an anchor session management network element corresponding to a first PDN connection. In one possible design, the apparatus further includes a memory for storing program instructions and data necessary for the mobility management element. When the device is a chip system, the device may be composed of a chip, or may include a chip and other discrete devices.

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

A ninth aspect provides a session management system, where the session management system includes the mobility management element in any aspect, and reference may be made to the foregoing embodiment for related description, which is not repeated herein.

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

Drawings

Fig. 1 is a schematic diagram of an existing interworking architecture between a 4G network and a 5G network;

fig. 2 is a schematic structural 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 fourth flowchart illustrating a session management method according to an embodiment of the present application;

fig. 8 is a fifth flowchart illustrating a session management method according to an embodiment of the present application;

fig. 9 is a sixth schematic flowchart of a session management method according to an embodiment of the present application;

fig. 10 is a schematic structural diagram of a mobility management network element according to an embodiment of the present application.

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.

The 4G network and 5G network intercommunication structure:

fig. 1 is a schematic diagram of an existing interworking 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, an SMF network element + a PGW-C network element, a Policy Control Function (PCF) network element + a Policy and Charging Rules Function (PCRF) network element, a Unified Data Management (UDM) network element + a Home Subscriber Server (HSS) +. 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 UDM network element and the HSS are referred to as a user data management network element, the SMF network element and the PGW-C network element are referred to as an anchor session management network element, and the UPF network element and the PGW-U network element are referred to as an anchor user plane network element, which are described herein in a unified manner and will not be described again. 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, the interworking 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 access and mobility management function (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 accesses the 4G network through an evolved universal terrestrial radio access network (E-UTRAN) device, and accesses the 5G network through a next generation radio access network (NG-RAN) device. 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 a UPF network element + PGW-U network element through an S5-U interface, the SGW communicates with the SMF network element + PGW-C network element through an S5-C interface, the UPF network element + PGW-U communicates with the UPF network element + PGW-RAN device through an N3 interface, the UPF network element + PGW-U network element communicates with the SMF network element + PGW-C network element through an N4 interface, the SMF network element + PGW-C network element communicates with the PCF network element + PCF network element through an N7 interface, the UDM network element + HSS communicates with the SMF network element + PGW-C network element through an N10 interface, the UDM network element + HS, the PCF network element and the PCRF network element are communicated with the AMF network element through an N15 interface, the SMF network element and the PGW-C 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.

It should be noted that the interface name between each network element in fig. 1 is only an example, and the interface name may be other names in a specific implementation, 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 to a core network, and may be, for example, a base station, a broadband network service gateway (BNG), a convergence switch, a non-3GPP (non-3GPP) 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 service function (AUSF) network element and the like, 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; 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), a cordless phone (cordless phone) or a Wireless Local Loop (WLL) station, a Machine Type Communication (MTC) terminal, a User Equipment (UE), a Mobile Station (MS), a terminal equipment (terminal device) or a relay user equipment, etc. may also be included. The relay user equipment may be, for example, a 5G home gateway (RG). For convenience of description, the above-mentioned devices are collectively referred to as a terminal in this 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. Where in the description of the present application, "/" indicates a relationship where the objects associated before and after are an "or", unless otherwise stated, for example, a/B may indicate a or B; in the present application, "and/or" is only an association relationship describing an associated object, and means that there may be three relationships, for example, a and/or B, and may mean: a exists alone, A and B exist simultaneously, and B exists alone, wherein A and B can be singular or plural. Also, in the description of the present application, "a plurality" means two or more than two unless otherwise specified. "at least one of the following" or similar expressions refer to any combination of these items, including any combination of the singular or plural items. For example, at least one (one) of a, b, or c, may represent: a, b, c, a-b, a-c, b-c, or a-b-c, wherein a, b, c may be single or multiple. 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.

In addition, 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 constitute a limitation to the technical solution provided in the embodiment of the present application, and it can be known by a person skilled in the art that the technical solution provided in the embodiment of the present application is also applicable to similar technical problems along with the evolution of the network architecture and the appearance of a new service scenario.

As shown in fig. 2, for a session management system 20 provided in the embodiment of the present application, the session management system 20 includes a mobility management network element 202. Optionally, a terminal 201 is included.

The terminal 201 is configured to send a request message to the mobility management network element 202, where the request message includes a handover instruction, and the handover instruction is used to instruct to switch a first PDU session corresponding to a first DNN to a first PDN connection corresponding to a first APN.

And the mobility management network element 202 is configured to receive the request message from the terminal 201, and determine, according to the request message, information of a first anchor session management network element in the information of the multiple anchor session management network elements corresponding to the first DNN as information of an anchor session management network element corresponding to the first PDN connection.

Optionally, the request message in the embodiment of the present application may be, for example, a PDN connection establishment request or an attach request, which is not specifically limited in the embodiment of the present application.

Optionally, in this embodiment of the application, the terminal 201 communicates with the mobility management element 202 through an access device in a network where the mobility management element 202 is located, which is described in a unified manner herein and will not be described in detail below.

Based on the session management system provided in the embodiment of the present application, after receiving the request message from the terminal, the mobility management network element determines, as the information of the anchor session management network element corresponding to the first PDN connection, the information of the first anchor session management network element in the information of the multiple anchor session management network elements corresponding to the first DNN, so that a corresponding PDN connection is established when multiple anchor session management network elements corresponding to different PDU sessions with the same DNN exist in the mobility management network element.

Optionally, the session management system shown in fig. 2 may be applied to an interworking architecture between a 4G network and a 5G network shown in fig. 1, where a network element or an entity corresponding to the mobility management network element may be the MME in fig. 1; the network element or entity corresponding to the anchor session management network element may be the SMF network element + PGW-C network element in fig. 1, which is not specifically limited in this application.

Optionally, the mobility management network element in fig. 2 in this embodiment of the present application may be implemented by one device, may also be implemented by multiple devices together, and may also be a 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 element in fig. 2 in the embodiment of the present application 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 comprises a processor 301, a communication line 302, a memory 303 and one or more communication interfaces (only one communication interface 304 is exemplarily illustrated in fig. 3).

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 computer, a laptop computer, a web server, a Personal Digital Assistant (PDA), a mobile phone, a tablet computer, 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 session management method provided by the embodiment of the present application will be specifically described below with reference to fig. 1 to 3.

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 an example that the session management system shown in fig. 2 is applied to a framework in which a 4G network and a 5G network shown in fig. 1 are intercommunicated, an N26 interface exists between an AMF network element and an MME, and a flow in which a 5G network in a connected state interworks to the 4G network is taken as an example, as shown in fig. 4, a session management method provided in an embodiment of the present application is provided. Before the process shown in fig. 4 is executed, the terminal establishes PDU sessions in the 5G core network, some PDU sessions are established through the 3GPP access network, some PDU sessions are established through the non-3GPP access network, and these PDU sessions may have the same DNN. For example, the DNN corresponding to PDU session 1 established by the terminal through the 3GPP access network is the same as the DNN corresponding to PDU session 2 established by the terminal through the non-3GPP access network; or, the DNN corresponding to the PDU session 1 established by the terminal through the 3GPP access network is the same as the DNN corresponding to another PDU session 3 established by the terminal through the 3GPP access network, which is not specifically limited in this embodiment of the present application. Furthermore, the session management method of the embodiment includes the following steps:

s401, when the connected terminal moves from the 5G network to the 4G network, the NG-RAN equipment in the 5G network sends a handover request (handover request) to the AMF network element, so that the AMF network element receives the handover request from the NG-RAN equipment.

S402, the AMF network element sends a session context request to the SMF network element and the PGW-C network element, so that the SMF network element and the PGW-C network element receive the session context request from the AMF network element.

It should be noted that, in this embodiment of the application, before step S401, when the terminal establishes a PDU session in the 5G network, for the PDU session that can be switched to the 4G network, information of a corresponding PDN connection is allocated to the PDU session, which is used for switching to the corresponding PDN connection when subsequently switching to the 4G network, and when the information of the corresponding PDN connection is allocated to a PDU session of different SMF network elements + PGW-C network elements of the same DNN, the AMF network element only allocates information of the corresponding PDN connection to the PDU session on one SMF network element + PGW-C network element, so in step S402, the AMF network element selects one of the SMF network elements + PGW-C network elements that have already allocated the information of the corresponding PDN connection, and further sends a session context request to the SMF network element + PGW-C network element, and related implementations may refer to an existing implementation manner, and will not be described in detail herein.

For example, the information of the PDN connection in the embodiment of the present application may include an Evolved Packet System (EPS) bearer identity (EBI), which is not specifically limited in the embodiment of the present application.

S403, the SMF network element + PGW-C network element sends a session context response to the AMF network element, so that the AMF network element receives the session context response from the SMF network element + PGW-C network element. Wherein, the session context response includes the session context of the terminal, and the session context of the terminal includes the information of the existing PDN connection.

Optionally, in this embodiment of the present application, the information of the existing PDN connection may be information of one PDN connection, or information of multiple PDN connections, which is not specifically limited in this embodiment of the present application.

Optionally, in this embodiment of the present application, the information about each PDN connection may include an APN corresponding to the PDN connection and information about an SMF network element + a PGW-C network element corresponding to the PDN connection, which are described in a unified manner herein and are not described in detail below.

S404, the AMF network element sends a redirection request (relocation request) to the MME through the N26 interface, so that the MME receives the redirection request from the AMF network element. Wherein the redirection request includes a session context of the terminal.

It should be noted that, in the above steps S402 to S403, an example of an interaction between the AMF network element and an SMF network element + PGW-C network element corresponding to one DNN is described. When the terminal has PDU sessions corresponding to different DNNs, for each SMF network element + PGW-C network element corresponding to the DNN, the interaction may be performed in a manner referring to the above steps S402 to S403, which is not specifically limited in this embodiment of the present application. That is to say, the context of the terminal may include information of one or more PDN connections, where the information of one PDN connection corresponds to information of one SMF network element + PGW-C network element, and this embodiment of the present application is not particularly limited to this.

S405, performing a part of the subsequent handover procedure, which may specifically refer to Technical Standard (TS) 23.502 of the third generation partnership project (3 GPP): "second part of 5G System Process (procedures for the 5 Gs; stage 2)" will not be described herein.

S406, the terminal sends a tracking area update (tracking area update) request to the MME through the E-UTRAN equipment so that the MME receives a TAU request from the terminal.

S407, the MME acquires the subscription data of the terminal from the UDM network element and the HSS.

In this embodiment of the present application, the subscription data of the terminal includes information of one or more SMF network elements + PGW-C network elements corresponding to the DNN, which is not specifically limited in this embodiment of the present application.

The specific implementation of step S407 may refer to an existing implementation manner, which is not described herein.

S408, executing a subsequent handover procedure, including a subsequent procedure of the TAU procedure and other handover procedures in the handover procedure, specifically referring to 3GPP TS23.502: "procedures for the 5G system; stage 2 ", which is not described in detail herein.

S409, the terminal sends a PDN connection establishment request to the MME through the E-UTRAN equipment, so that the MME receives the PDN connection establishment request from the terminal.

The PDN connection establishment request comprises a switching instruction, wherein the switching instruction is used for instructing to switch a first PDU session corresponding to a first DNN to a first PDN connection corresponding to a first APN.

For example, the handover indication may be a request type of the PDN connection establishment request, where the request type is "handover", or the handover indication may also be a new information element in the PDN connection establishment request, which is not specifically limited in this embodiment of the present invention.

For example, the triggering condition of step S409 may be: after the terminal is handed over to the 4G network, it finds that the access signal through the non-3GPP access network is too poor, and therefore, the terminal switches the PDU session established through the non-3GPP access network to the PDN connection accessed through the E-UTRAN of the 4G network, which is not specifically limited in this embodiment of the present application.

S410, the MME determines the information of the first SMF network element and the PGW-C network element in the information of the plurality of SMF network elements and PGW-C network elements corresponding to the first DNN as the information of the SMF network elements and PGW-C network elements corresponding to the first PDN according to the PDN connection establishment request and the information of the existing PDN connection.

In this embodiment of the present application, the existing PDN connection information refers to the PDN connection information in the session context received by the MME from the AMF network element in step S404, and is herein collectively described, and is not described again below.

Optionally, in this embodiment of the application, when the existing PDN connection information includes the PDN connection information corresponding to the first APN, the MME determines, according to the PDN connection establishment request, information of the SMF network element + PGW-C network element in the PDN connection information corresponding to the first APN as information of the SMF network element + PGW-C network element corresponding to the first PDN connection.

Or, optionally, in this embodiment of the application, when the existing information of the PDN connection does not include the information of the PDN connection corresponding to the first APN, the MME determines, according to the PDN connection establishment request and the subscription data of the terminal, the information of the first SMF network element + PGW-C network element in the information of the multiple SMF network elements + PGW-C network elements corresponding to the first DNN as the information of the SMF network element + PGW-C network element corresponding to the first PDN connection. For example, the MME selects, according to the PDN connection establishment request, information of the first SMF network element + PGW-C network element from information of the multiple SMF network elements + PGW-C network elements corresponding to the first DNN in the subscription data, in combination with a preset policy or load information of the SMF network elements + PGW-C network elements, and the like, as information of the SMF network element + PGW-C network element corresponding to the first PDN connection.

S411, optionally, the MME deletes, from the information of the multiple SMF network elements + PGW-C network elements corresponding to the first DNN, information of the other SMF network elements + PGW-C network elements except for the information of the first SMF network element + PGW-C network element; or the MME marks, as unavailable, information of other SMF network elements + PGW-C network elements, except for the information of the first SMF network element + PGW-C network element, in the information of the plurality of SMF network elements + PGW-C network elements corresponding to the first DNN; or the MME marks the information of the first SMF network element + PGW-C network element in the information of the multiple SMF network elements + PGW-C network elements corresponding to the first DNN as available.

That is to say, in this embodiment of the application, the MME may further process redundant information in the information of the multiple SMF network elements + PGW-C network elements corresponding to the first DNN, for example, delete the redundant information or mark the redundant information. The method for establishing the PDN connection with the APN comprises the steps that redundant information is deleted or marked, and the method can be used for enabling a follow-up terminal to initiate the PDN connection establishment process carrying the first APN, the MME does not select the SMF network elements and the PGW-C network elements, and it is guaranteed that different PDN connections of the terminal corresponding to the same APN can only be served by one SMF network element and one PGW-C network element, and therefore the problem of possible switching failure is avoided. In addition, the redundant information is deleted, so that the storage space of the MME can be saved.

Optionally, it is considered that when the terminal accesses the 3GPP side and the non-3GPP side simultaneously in the 5G network and there are PDU sessions on the 3GPP side and the non-3GPP side, respectively, there may be a case where the same DNN but the terminal accesses different SMF network element + PGW-C network elements on the 3GPP side and the non-3GPP side. When the terminal is handed over to the 4G network, the PDU session on the non-3GPP side may also be handed over to the 3GPP side of the 4G network. When a subsequent terminal wishes to switch from the 3GPP side of the 4G network to the non-3GPP side of the 4G network (for example, when a subsequent wireless fidelity (WIFI) signal is lost), an authentication, authorization, and accounting (AAA) server (server) may obtain subscription information of the terminal from the UDM network element + HSS, and the subscription data of the terminal stored in the UDM network element + HSS and the DNN/APN may correspond to information of different SMF network elements + PGW-C network elements, at this time, when a trusted non-3GPP (trusted non-3GPP) access device or an evolved packet data gateway (ePDG) may obtain the subscription data of the terminal from the server, and when an SMF + PGW-C network element is selected according to the subscription data of the terminal, a problem may occur that the network element selected by the 3GPP side of the 4G network is different from the network element selected by the 3GPP + PGW-C network element, the principle that different PDN connections of a terminal corresponding to the same APN can only be served by one SMF network element + PGW-C network element in the existing 4G network is not met, which may further cause handover failure. Based on this, the session management method provided in the embodiment of the present application may further include the following step S412:

s412, the MME sends indication information to the UDM network element + HSS, so that the UDM network element + HSS receives the indication information from the MME, and the indication information is used for indicating the information of the first SMF network element + PGW-C network element selected by the MME.

For example, the indication information may be, for example, information of the first SMF network element + PGW-C network element and a first DNN of the information of the first SMF network element + PGW-C network element, which is not specifically limited in this embodiment of the present application.

In this way, after the UDM network element + HSS obtains the information of the first SMF network element + PGW-C network element selected by the MME, the information of the other SMF network elements + PGW-C network elements, except the information of the first SMF network element + PGW-C network element, in the information of the plurality of SMF network elements + PGW-C network elements corresponding to the first DNN may be deleted; or marking the information of the SMF network element + PGW-C network elements other than the information of the first SMF network element + PGW-C network element in the information of the plurality of SMF network elements + PGW-C network elements corresponding to the first DNN as unavailable. Furthermore, when switching to the non-3GPP side in the subsequent process, the subscription data of the terminal sent to the AAA server by the UDM network element and the HSS is the information of the first SMF network element and the PGW-C network element under the DNN; or, the UDM network element + HSS sends the marked information of the SMF network elements + PGW-C network elements corresponding to the first DNN to the AAA server, wherein the information of the SMF network elements + PGW-C network elements is the information of other SMF network elements + PGW-C network elements except the information of the first SMF network element + PGW-C network elements; or the UDM network element + HSS sends the subscription data of the undeleted or unmarked terminal to the AAA server, but carries information indicating that the MME has selected the first SMF network element + PGW-C network element, and so on, so that the same SMF network element + PGW-C network element as the 3GPP side is selected for the same APN/DNN at the non-3GPP side. That is to say, it can be ensured that different PDN connections of a terminal corresponding to the same APN can only be served by one SMF network element + PGW-C network element, thereby avoiding a problem of handover failure that may be caused.

Wherein, the process of switching to non-3GPP is the prior art, and the specific process refers to 3GPP TS 23.402: the "non-3 GPP access architecture enhancements (non-3GPP accesses)" part will not be described herein.

And S413, executing a subsequent PDN connection establishing process.

In the subsequent PDN connection establishment procedure, the first SMF network element + PGW-C network element selected by the MME may determine, according to a PDU session identifier sent by the terminal in a Protocol Configuration Option (PCO), whether a PDU session corresponding to the PDN connection is served by itself in the 5G network, and if not, the PDU session cannot be switched to the first SMF network element + PGW-C network element, so that the first SMF network element + PGW-C network element rejects the PDN connection establishment, and the related implementation may refer to an existing implementation manner, which is not described herein again.

Based on the session management method provided in the embodiment of the present application, on one hand, after receiving a PDN connection establishment request from a terminal, an MME may determine, by combining information of an existing PDN connection, information of a first SMF network element + PGW-C network element in information of multiple SMF network elements + PGW-C network elements corresponding to a first DNN as information of the SMF network element + PGW-C network element corresponding to the first PDN connection, so that, in a case where multiple SMF network elements + PGW-C network elements corresponding to different PDU sessions with the same DNN exist in the MME, the corresponding PDN connection is successfully established. On the other hand, as the MME can process the redundant data and can also send, to the UDM network element + HSS, indication information for indicating information of the first SMF network element + PGW-C network element selected by the MME, it is possible to avoid a problem that when the terminal subsequently switches to the non-3GPP side again, the selection of the SMF network element + PGW-C network element is inconsistent and the switching fails.

The operations of the MME in steps S401 to S403 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.

Optionally, taking a structure that the session management system shown in fig. 2 is applied to the interworking between the 4G network and the 5G network shown in fig. 1, where an N26 interface exists between the AMF network element and the MME, and a flow that the 5G network in a connected state interworks with the 4G network is taken as an example, as shown in fig. 5, a session management method provided in the embodiment of the present application is provided. Before the process shown in fig. 5 is executed, the terminal establishes PDU sessions in the 5G core network, some PDU sessions are established through the 3GPP access network, some PDU sessions are established through the non-3GPP access network, and these PDU sessions may have the same DNN. For example, the DNN corresponding to PDU session 1 established by the terminal through the 3GPP access network is the same as the DNN corresponding to PDU session 2 established by the terminal through the non-3GPP access network; or, the DNN corresponding to the PDU session 1 established by the terminal through the 3GPP access network is the same as the DNN corresponding to another PDU session 3 established by the terminal through the 3GPP access network, which is not specifically limited in this embodiment of the present application. Furthermore, the session management method of the embodiment includes the following steps:

s501 to S507, similar to steps S401 to S407 in the embodiment shown in fig. 4, the related description may refer to the embodiment shown in fig. 4, and will not be repeated herein.

S508-S510, assuming that any DNN of the one or more DNNs in the subscription data of the terminal is referred to as a first DNN, and a DNN corresponding to a first PDN connection that needs to be established subsequently is the first DNN, the MME may refer to the manner in steps S410-S412 to execute, for example, in the embodiment shown in fig. 4, after the MME receives a PDN connection establishment request from the terminal, according to the PDN connection establishment request and information of an existing PDN connection, determine, as information of an SMF network element + a PGW-C network element in information of a plurality of SMF network elements + a PGW-C network elements corresponding to the first DNN, information of the SMF network element + the PGW-C network element corresponding to the first PDN connection; in this embodiment of the application, the MME may determine, in the TAU flow, information of a first SMF network element + PGW-C network element in the information of the multiple SMF network elements + PGW-C network elements corresponding to the first DNN as information of an SMF network element + PGW-C network element corresponding to the first PDN connection, and for related description, reference may be made to the embodiment shown in fig. 4, which is not described herein again.

S511, executing a subsequent handover procedure, including a subsequent procedure of a TAU procedure and other handover procedures in the handover procedure, specifically referring to 3GPP TS23.502: "procedures for the 5G system; stage 2 ", which is not described in detail herein.

Based on the session management method provided in the embodiment of the present application, on one hand, after receiving the TAU request from the terminal, the MME may determine, by combining with the information of the existing PDN connection, the information of the first SMF network element + PGW-C network element in the information of the multiple SMF network elements + PGW-C network elements corresponding to the first DNN as the information of the SMF network element + PGW-C network element corresponding to the first PDN connection, so that, in a case where multiple SMF network elements + PGW-C network elements corresponding to different PDU sessions with the same DNN exist in the MME, the corresponding PDN connection is successfully established. On the other hand, as the MME can process the redundant data and can also send, to the UDM network element + HSS, indication information for indicating information of the first SMF network element + PGW-C network element selected by the MME, it is possible to avoid a problem that when the terminal subsequently switches to the non-3GPP side again, the selection of the SMF network element + PGW-C network element is inconsistent and the switching fails.

The operations of the MME in steps S501 to S511 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.

Optionally, taking a structure that the session management system shown in fig. 2 is applied to the interworking between the 4G network and the 5G network shown in fig. 1, where an N26 interface exists between the AMF network element and the MME, and a flow that the 5G network in an idle state interworks with the 4G network is taken as an example, as shown in fig. 6, a session management method provided in the embodiment of the present application is provided. Before the process shown in fig. 5 is executed, the terminal establishes PDU sessions in the 5G core network, some PDU sessions are established through the 3GPP access network, some PDU sessions are established through the non-3GPP access network, and these PDU sessions may have the same DNN. For example, the DNN corresponding to PDU session 1 established by the terminal through the 3GPP access network is the same as the DNN corresponding to PDU session 2 established by the terminal through the non-3GPP access network; or, the DNN corresponding to the PDU session 1 established by the terminal through the 3GPP access network is the same as the DNN corresponding to another PDU session 3 established by the terminal through the 3GPP access network, which is not specifically limited in this embodiment of the present application. Furthermore, the session management method of the embodiment includes the following steps:

S601-S602, similar to steps S406-S407 in the embodiment shown in fig. 4, the related description may refer to the embodiment shown in fig. 4, and will not be repeated herein.

S603, MME obtains the session context of the terminal from the AMF network element, and the session context of the terminal comprises the information of the existing PDN connection.

For the related implementation of step S603, reference may be made to an existing implementation manner, which is not described herein again.

S604, executing a subsequent TAU procedure, which may specifically refer to 3GPP TS23.502: "procedures for the 5 Gsystem; stage 2 ", which is not described in detail herein.

S605-S609, similar to steps S409-S413 in the embodiment shown in fig. 4, for related description, reference may be made to the embodiment shown in fig. 4, and details are not repeated here.

Based on the session management method provided in the embodiment of the present application, on one hand, after receiving a PDN connection establishment request from a terminal, an MME may determine, by combining information of an existing PDN connection, information of a first SMF network element + PGW-C network element in information of multiple SMF network elements + PGW-C network elements corresponding to a first DNN as information of the SMF network element + PGW-C network element corresponding to the first PDN connection, so that a corresponding PDN connection may be established in a case where multiple SMF network elements + PGW-C network elements corresponding to different PDU sessions with the same DNN exist in the MME. On the other hand, as the MME can process the redundant data and can also send, to the UDM network element + HSS, indication information for indicating information of the first SMF network element + PGW-C network element selected by the MME, it is possible to avoid a problem that when the terminal subsequently switches to the non-3GPP side again, the selection of the SMF network element + PGW-C network element is inconsistent and the switching fails.

The actions of the MME in steps S601 to S609 described above 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.

Optionally, taking a structure that the session management system shown in fig. 2 is applied to the interworking between the 4G network and the 5G network shown in fig. 1, where an N26 interface exists between the AMF network element and the MME, and a flow that the 5G network in an idle state interworks with the 4G network is taken as an example, as shown in fig. 7, a session management method provided in the embodiment of the present application is provided. Before the process shown in fig. 7 is executed, the terminal establishes PDU sessions in the 5G core network, some PDU sessions are established through the 3GPP access network, some PDU sessions are established through the non-3GPP access network, and these PDU sessions may have the same DNN. For example, the DNN corresponding to PDU session 1 established by the terminal through the 3GPP access network is the same as the DNN corresponding to PDU session 2 established by the terminal through the non-3GPP access network; or, the DNN corresponding to the PDU session 1 established by the terminal through the 3GPP access network is the same as the DNN corresponding to another PDU session 3 established by the terminal through the 3GPP access network, which is not specifically limited in this embodiment of the present application. Furthermore, the session management method of the embodiment includes the following steps:

s701 to S703, similar to steps S601 to S603 in the embodiment shown in fig. 6, for related description, reference may be made to the embodiment shown in fig. 6, and details are not repeated here.

S704-S706, similar to steps S508-S510 in the embodiment shown in fig. 5, the related description may refer to the embodiment shown in fig. 5, and will not be repeated herein.

S707, execute the TAU procedure, which may specifically refer to 3GPP TS23.502: "procedures for the 5 Gsystem; stage 2 ", which is not described in detail herein.

Based on the session management method provided in the embodiment of the present application, on one hand, after receiving the TAU request from the terminal, the MME may determine, by combining with the information of the existing PDN connection, the information of the first SMF network element + PGW-C network element in the information of the multiple SMF network elements + PGW-C network elements corresponding to the first DNN as the information of the SMF network element + PGW-C network element corresponding to the first PDN connection, so that, in a case where multiple SMF network elements + PGW-C network elements corresponding to different PDU sessions with the same DNN exist in the MME, the corresponding PDN connection may be established. On the other hand, as the MME can process the redundant data and can also send, to the UDM network element + HSS, indication information for indicating information of the first SMF network element + PGW-C network element selected by the MME, it is possible to avoid a problem that when the terminal subsequently switches to the non-3GPP side again, the selection of the SMF network element + PGW-C network element is inconsistent and the switching fails.

The actions of the MME in steps S701 to S707 above 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.

Optionally, taking an architecture that the session management system shown in fig. 2 is applied to the interworking between the 4G network and the 5G network shown in fig. 1, for example, an N26 interface does not exist between the AMF network element and the MME, as shown in fig. 8, a session management method provided in the embodiment of the present application is provided. Before the process shown in fig. 8 is executed, the terminal establishes PDU sessions in the 5G core network, some PDU sessions are established through the 3GPP access network, some PDU sessions are established through the non-3GPP access network, and these PDU sessions may have the same DNN. For example, the DNN corresponding to PDU session 1 established by the terminal through the 3GPP access network is the same as the DNN corresponding to PDU session 2 established by the terminal through the non-3GPP access network; or, the DNN corresponding to the PDU session 1 established by the terminal through the 3GPP access network is the same as the DNN corresponding to another PDU session 3 established by the terminal through the 3GPP access network, which is not specifically limited in this embodiment of the present application. Furthermore, the session management method of the embodiment includes the following steps:

s801, the terminal sends an attachment request to the MME through the E-UTRAN equipment so that the MME receives the attachment request from the terminal.

Optionally, in this embodiment of the application, the attach request may include a PDN connection establishment request, where the PDN connection establishment request includes a handover instruction, and the handover instruction is used to instruct to switch the second PDU session corresponding to the first DNN to the second PDN connection corresponding to the first APN.

S802, similar to step S407 in the embodiment shown in fig. 4, the related description may refer to the embodiment shown in fig. 4, and is not repeated herein.

And S803, executing the subsequent attaching process.

Optionally, if the attach request in step S801 includes a PDN connection establishment request, where the PDN connection establishment request includes a handover indication, the MME may further determine, according to the PDN connection establishment request and subscription data of the terminal, information of a first SMF network element + PGW-C network element in information of multiple SMF network elements + PGW-C network elements corresponding to the first DNN as information of the SMF network element + PGW-C network element corresponding to the first PDN connection, which is not specifically limited in this embodiment of the present application. Wherein, the rest steps of the attachment process can refer to 3GPP TS23.502: "procedures for the 5G system; stage 2 ", which is not described in detail herein.

S804, similar to step S409 in the embodiment shown in fig. 4, the related description may refer to the embodiment shown in fig. 4, and is not repeated herein.

S805, the MME determines the information of the first SMF network element and the PGW-C network element in the information of the plurality of SMF network elements and PGW-C network elements corresponding to the first DNN as the information of the SMF network element and PGW-C network element corresponding to the first PDN according to the PDN connection establishment request.

Optionally, if the existing information of the PDN connection exists in the MME, the MME determines, according to the existing information of the PDN connection, information of the first SMF network element + PGW-C network element in the information of the multiple SMF network elements + PGW-C network elements corresponding to the first DNN, as the information of the SMF network element + PGW-C network element corresponding to the first PDN connection, and related descriptions may refer to the embodiment shown in fig. 4, and are not described here again.

Or, if the existing information of the PDN connection does not exist in the MME, the MME determines, according to the subscription data of the terminal, information of the first SMF network element + PGW-C network element in the information of the multiple SMF network elements + PGW-C network elements corresponding to the first DNN as information of the SMF network element + PGW-C network element corresponding to the first PDN connection, and related description may refer to the embodiment shown in fig. 4, which is not described herein again.

Optionally, in this embodiment of the application, the information of the existing PDN connections in the MME may be information of one or more PDN connections established by the terminal through the MME in the attach procedure (steps S801 to S803); or, when the terminal supports dual registration, the above steps S801 to S803 are not performed, and before step S804 is performed, the terminal has already established one or more PDN connections through the MME, where the PDN connections correspond to existing PDN connections, which is described in a unified manner herein and is not described again below.

S806-S808, similar to steps S411-S413 in the embodiment shown in fig. 4, for related description, reference may be made to the embodiment shown in fig. 4, and details are not repeated here.

Based on the session management method provided in the embodiment of the present application, on one hand, after receiving a PDN connection establishment request from a terminal, an MME may determine, according to subscription data of the terminal, information of a first SMF network element + PGW-C network element in information of multiple SMF network elements + PGW-C network elements corresponding to a first DNN as information of the SMF network element + PGW-C network element corresponding to the first PDN connection, so that a corresponding PDN connection may be established in a case where multiple SMF network elements + PGW-C network elements corresponding to different PDU sessions with the same DNN exist in the MME. On the other hand, as the MME can process the redundant data and can also send, to the UDM network element + HSS, indication information for indicating information of the first SMF network element + PGW-C network element selected by the MME, it is possible to avoid a problem that when the terminal subsequently switches to the non-3GPP side again, the selection of the SMF network element + PGW-C network element is inconsistent and the switching fails.

The operations of the MME in steps S801 to S808 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.

Optionally, taking an architecture that the session management system shown in fig. 2 is applied to the interworking between the 4G network and the 5G network shown in fig. 1, for example, an N26 interface does not exist between the AMF network element and the MME, as shown in fig. 9, a session management method provided in the embodiment of the present application is provided. Before the process shown in fig. 9 is executed, the terminal establishes PDU sessions in the 5G core network, some PDU sessions are established through the 3GPP access network, some PDU sessions are established through the non-3GPP access network, and these PDU sessions may have the same DNN. For example, the DNN corresponding to PDU session 1 established by the terminal through the 3GPP access network is the same as the DNN corresponding to PDU session 2 established by the terminal through the non-3GPP access network; or, the DNN corresponding to the PDU session 1 established by the terminal through the 3GPP access network is the same as the DNN corresponding to another PDU session 3 established by the terminal through the 3GPP access network, which is not specifically limited in this embodiment of the present application. Furthermore, the session management method of the embodiment includes the following steps:

s901 to S902, similar to steps S801 to S802 in the embodiment shown in fig. 8, the related description may refer to the embodiment shown in fig. 8, and will not be repeated herein.

S903-S905, assuming that a first DNN is recorded as any one of one or more DNNs in the subscription data of the terminal, and a DNN corresponding to a first PDN connection to be subsequently established is the first DNN, the MME may refer to the manner in steps S805-S807 to execute, for example, in the embodiment shown in fig. 8, after the MME receives a PDN connection establishment request from the terminal, according to the PDN connection establishment request and information of an existing PDN connection, determine, as information of an SMF network element + a PGW-C network element in information of a plurality of SMF network elements + a PGW-C network elements corresponding to the first DNN, information of the SMF network element + the PGW-C network element corresponding to the first PDN connection; in this embodiment of the application, the MME may determine, in the attach procedure, information of the first SMF network element + PGW-C network element in the information of the multiple SMF network elements + PGW-C network elements corresponding to the first DNN as information of the SMF network element + PGW-C network element corresponding to the first PDN connection, and for related description, reference may be made to the embodiment shown in fig. 4, which is not described herein again.

And S906, executing a subsequent attaching process. Wherein the subsequent attach procedure includes the establishment procedure of the PDN connection requested in step S901. Specifically, since the information of the SMF network element + PGW-C network element corresponding to the first PDN connection has been determined in step S903, after the MME subsequently receives a PDN connection establishment request carrying a first APN and used for establishing the first PDN, the MME may directly establish the corresponding first PDN connection according to the information of the SMF network element + PGW-C network element. The remaining description of the attachment procedure may refer specifically to 3GPP TS23.502: "procedures for the 5G system; stage 2 ", which is not described in detail herein.

Based on the session management method provided in the embodiment of the present application, on one hand, after receiving an attach request from a terminal, an MME may determine, according to subscription data of the terminal, information of a first SMF network element + PGW-C network element in information of multiple SMF network elements + PGW-C network elements corresponding to a first DNN as information of the SMF network element + PGW-C network element corresponding to the first PDN connection, so that a corresponding PDN connection may be established when multiple SMF network elements + PGW-C network elements corresponding to different PDU sessions with the same DNN exist in the MME. On the other hand, as the MME can process the redundant data and can also send, to the UDM network element + HSS, indication information for indicating information of the first SMF network element + PGW-C network element selected by the MME, it is possible to avoid a problem that when the terminal subsequently switches to the non-3GPP side again, the selection of the SMF network element + PGW-C network element is inconsistent and the switching fails.

The actions of the MME in steps S901 to S906 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.

Optionally, in this embodiment of the application, if an existing flow of interworking from a 5G network to a 4G network is executed, in a subsequent PDN connection new-establishment flow, if information of PDN connection corresponding to a first APN does not exist in an MME, the MME may obtain subscription data of the terminal, and further determine, according to the subscription data of the terminal, information of a first SMF network element + PGW-C network element in information of multiple SMF network elements + PGW-C network elements corresponding to a first DNN as information of the SMF network element + PGW-C network element corresponding to the first PDN connection, where the first DNN is a DNN corresponding to the first APN. For example, the MME selects, by combining a preset policy or load information of the SMF network element + PGW-C network element, information of the first SMF network element + PGW-C network element from information of the multiple SMF network elements + PGW-C network elements corresponding to the first DNN in the subscription data as information of the SMF network element + PGW-C network element corresponding to the first PDN connection, which is not specifically limited in this embodiment of the present application.

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 appreciated that the mobility management element comprises corresponding hardware structures and/or software modules for performing the respective functions in order to implement the above-described 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 of the mobility management network element may be divided according to the above method example, 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 each functional module in an integrated manner, fig. 10 shows a schematic structural diagram of a mobility management network element 100. The mobility management network element 100 comprises: a transceiver module 1002 and a processing module 1001. A transceiving module 1002, configured to receive a request message from a terminal, where the request message includes a handover indication, and the handover indication is used to indicate to switch a first PDU session corresponding to a first DNN to a first PDN connection corresponding to a first APN. A processing module 1001, configured to determine, according to the request message, information of a first anchor session management network element in the information of the multiple anchor session management network elements corresponding to the first DNN as information of an anchor session management network element corresponding to the first PDN connection.

In one possible implementation, the processing module 1001 is specifically configured to: and determining the information of the first anchor point session management network element in the information of the anchor point session management network elements corresponding to the first DNN as the information of the anchor point session management network element corresponding to the first PDN according to the request message and the existing information of the PDN connection.

Optionally, the processing module 1001 is configured to determine, according to the request message and the existing information about the PDN connection, information about a first anchor session management network element in the information about the multiple anchor session management network elements corresponding to the first DNN as information about an anchor session management network element corresponding to the first PDN connection, and includes: and determining the information of the anchor point session management network element in the information of the PDN connection corresponding to the first APN as the information of the anchor point session management network element corresponding to the first PDN connection according to the request message under the condition that the existing information of the PDN connection includes the information of the PDN connection corresponding to the first APN.

Or, optionally, the processing module 1001 is configured to determine, according to the request message and the existing information about the PDN connection, information about a first anchor session management network element in the information about the multiple anchor session management network elements corresponding to the first DNN as information about an anchor session management network element corresponding to the first PDN connection, and includes: and determining the information of the first anchor point session management network element in the information of the multiple anchor point session management network elements corresponding to the first DNN as the information of the anchor point session management network element corresponding to the first PDN according to the request message and subscription data of the terminal under the condition that the information of the PDN connection does not include the information of the PDN connection corresponding to the first APN, wherein the subscription data includes the information of the multiple anchor point session management network elements corresponding to the first DNN.

In another possible implementation manner, the processing module 1001 is specifically configured to: and determining the information of the first anchor point session management network element in the information of the anchor point session management network elements corresponding to the first DNN as the information of the anchor point session management network element corresponding to the first PDN connection according to the request message and the subscription data of the terminal, wherein the subscription data comprises the information of the anchor point session management network elements corresponding to the first DNN.

Optionally, the processing module 1001 is further configured to delete information of other anchor point session management network elements in the information of the multiple anchor point session management network elements corresponding to the first DNN, except for the information of the first anchor point session management network element.

Or, optionally, the processing module 1001 is further configured to mark, as unavailable, information of other anchor session management network elements in the information of the multiple anchor session management network elements corresponding to the first DNN except the information of the first anchor session management network element.

Or, optionally, the processing module 1001 is further configured to mark, as available, information of the first anchor session management network element in the information of the multiple anchor session management network elements corresponding to the first DNN.

Optionally, the transceiver module 1002 is further configured to send indication information to the user data management network element, where the indication information is used to indicate information of the first anchor session management network element selected by the mobility management network element.

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 present embodiment, the mobility management element 100 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, it will be appreciated by those skilled in the art that the mobility management element 100 may take the form shown in fig. 3.

For example, the processor 301 in fig. 3 may cause the mobility management element 100 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.

Specifically, the functions/implementation procedures of the transceiver module 1002 and the processing module 1001 in fig. 10 can be implemented by the processor 301 in fig. 3 calling a computer executing instruction stored in the memory 303. Alternatively, the function/implementation procedure of the processing module 1001 in fig. 10 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 1002 in fig. 10 may be implemented by the communication interface 304 in fig. 3.

Since the mobility management element 100 provided in this embodiment can execute the session management method, the technical effect obtained by the mobility management element 100 can refer to the method embodiment described above, and is not described herein again.

Optionally, an apparatus (for example, the apparatus may be a chip system) is further provided in this embodiment of the present application, where the apparatus includes a processor, configured to support a mobility management network element to implement the session management method, for example, according to a request message, determine, as information of an anchor session management network element corresponding to a first PDN connection, information of a first anchor session management network element in information of multiple anchor session management network elements corresponding to the first DNN. In one possible design, the apparatus 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 device. When the device is a chip system, the device may be composed of a chip, and may also include a chip and other discrete devices, which is not specifically limited in this application embodiment.

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 session management method, characterized in that the session management method comprises:

a mobile management network element receives a request message from a terminal, wherein the request message comprises a switching instruction, and the switching instruction is used for instructing to switch a first Packet Data Unit (PDU) session corresponding to a first Data Network Name (DNN) to a first Packet Data Network (PDN) connection corresponding to a first Access Point Name (APN);

and the mobility management network element determines the information of the first anchor point session management network element in the information of the anchor point session management network elements corresponding to the first DNN as the information of the anchor point session management network element corresponding to the first PDN connection according to the request message.

2. The session management method of claim 1, wherein the determining, by the mobility management network element according to the request message, information of a first anchor session management network element in the information of the anchor session management network elements corresponding to the first DNN as information of an anchor session management network element corresponding to the first PDN connection comprises:

and the mobility management network element determines the information of the first anchor point session management network element in the information of the anchor point session management network elements corresponding to the first DNN as the information of the anchor point session management network element corresponding to the first PDN according to the request message and the information of the existing PDN connection.

3. The session management method of claim 2, wherein the determining, by the mobility management network element according to the request message and information of the existing PDN connection, information of a first anchor session management network element in the information of the anchor session management network elements corresponding to the first DNN as information of an anchor session management network element corresponding to the first PDN connection comprises:

and when the existing PDN connection information comprises the PDN connection information corresponding to the first APN, the mobile management network element determines the anchor point session management network element information in the PDN connection information corresponding to the first APN as the anchor point session management network element information corresponding to the first PDN connection according to the request message.

4. The session management method of claim 2, wherein the determining, by the mobility management network element according to the request message and information of the existing PDN connection, information of a first anchor session management network element in the information of the anchor session management network elements corresponding to the first DNN as information of an anchor session management network element corresponding to the first PDN connection comprises:

and under the condition that the information of the PDN connection does not include the information of the PDN connection corresponding to the first APN, the mobility management network element determines, according to the request message and subscription data of the terminal, information of a first anchor session management network element in the information of the anchor session management network elements corresponding to the first DNN as the information of the anchor session management network element corresponding to the first PDN connection, wherein the subscription data includes the information of the anchor session management network elements corresponding to the first DNN.

5. The session management method of claim 1, wherein the determining, by the mobility management network element according to the request message, information of a first anchor session management network element in the information of the anchor session management network elements corresponding to the first DNN as information of an anchor session management network element corresponding to the first PDN connection comprises:

and the mobility management network element determines, according to the request message and subscription data of the terminal, information of a first anchor session management network element in information of a plurality of anchor session management network elements corresponding to the first DNN as information of an anchor session management network element corresponding to the first PDN connection, where the subscription data includes information of the plurality of anchor session management network elements corresponding to the first DNN.

6. The session management method of any one of claims 1 to 5, wherein after the mobility management network element determines, according to the request message, information of a first anchor session management network element in the information of the anchor session management network elements corresponding to the first DNN as information of an anchor session management network element corresponding to the first PDN connection, the session management method further comprises:

and the mobility management network element deletes the information of the anchor point session management network elements except the information of the first anchor point session management network element in the information of the anchor point session management network elements corresponding to the first DNN.

7. The session management method of any one of claims 1 to 5, wherein after the mobility management network element determines, according to the request message, information of a first anchor session management network element in the information of the anchor session management network elements corresponding to the first DNN as information of an anchor session management network element corresponding to the first PDN connection, the session management method further comprises:

the mobility management network element marks the information of other anchor point session management network elements except the information of the first anchor point session management network element in the information of the anchor point session management network elements corresponding to the first DNN as unavailable; or, the mobility management network element marks, as available, the information of the first anchor session management network element in the information of the anchor session management network elements corresponding to the first DNN.

8. The session management method according to any one of claims 1 to 7, wherein the session management method further comprises:

and the mobility management network element sends indication information to a user data management network element, wherein the indication information is used for indicating the information of the first anchor point session management network element selected by the mobility management network element.

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

the receiving and sending module is configured to receive a request message from a terminal, where the request message includes a switching instruction, and the switching instruction is used to instruct to switch a first packet data unit PDU session corresponding to a first data network name DNN to a first packet data network PDN connection corresponding to a first access point name APN;

and the processing module is configured to determine, according to the request message, information of a first anchor session management network element in the information of the multiple anchor session management network elements corresponding to the first DNN as information of an anchor session management network element corresponding to the first PDN connection.

10. The mobility management element according to claim 9, wherein the processing module is specifically configured to:

and determining the information of the first anchor point session management network element in the information of the anchor point session management network elements corresponding to the first DNN as the information of the anchor point session management network element corresponding to the first PDN connection according to the request message and the information of the existing PDN connection.

11. The mobility management network element of claim 10, wherein the processing module is configured to determine, according to the request message and information of the existing PDN connection, information of a first anchor session management network element in the information of the anchor session management network elements corresponding to the first DNN as information of an anchor session management network element corresponding to the first PDN connection, and includes:

and the method is used for determining the information of the anchor point session management network element in the information of the PDN connection corresponding to the first APN as the information of the anchor point session management network element corresponding to the first PDN connection according to the request message when the information of the existing PDN connection includes the information of the PDN connection corresponding to the first APN.

12. The mobility management network element of claim 10, wherein the processing module is configured to determine, according to the request message and information of the existing PDN connection, information of a first anchor session management network element in the information of the anchor session management network elements corresponding to the first DNN as information of an anchor session management network element corresponding to the first PDN connection, and includes:

and determining, according to the request message and subscription data of the terminal, information of a first anchor session management network element in information of a plurality of anchor session management network elements corresponding to the first DNN as information of the anchor session management network element corresponding to the first PDN connection, where the subscription data includes information of the plurality of anchor session management network elements corresponding to the first DNN.

13. The mobility management element according to claim 9, wherein the processing module is specifically configured to:

and determining the information of the first anchor point session management network element in the information of the anchor point session management network elements corresponding to the first DNN as the information of the anchor point session management network element corresponding to the first PDN connection according to the request message and the subscription data of the terminal, where the subscription data includes the information of the anchor point session management network elements corresponding to the first DNN.

14. Mobility management network element according to any of claims 9-13,

the processing module is further configured to delete information of other anchor session management network elements, except the information of the first anchor session management network element, in the information of the anchor session management network elements corresponding to the first DNN.

15. Mobility management network element according to any of claims 9-13,

the processing module is further configured to mark, as unavailable, information of other anchor session management network elements, except the information of the first anchor session management network element, in the information of the anchor session management network elements corresponding to the first DNN;

or, the processing module is further configured to mark, as available, the information of the first anchor session management network element in the information of the multiple anchor session management network elements corresponding to the first DNN.

16. Mobility management network element according to any of claims 9-15,

the transceiver module is further configured to send indication information to a user data management network element, where the indication information is used to indicate information of the first anchor session management network element selected by the mobility management network element.

17. A session management system, the session management system method comprising: a mobility management element as claimed in any one of claims 9 to 16.