CN110049072B

CN110049072B - Session establishment method and device

Info

Publication number: CN110049072B
Application number: CN201810037102.9A
Authority: CN
Inventors: 景昊
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2018-01-15
Filing date: 2018-01-15
Publication date: 2021-09-21
Anticipated expiration: 2038-01-15
Also published as: WO2019137547A1; CN110049072A

Abstract

The embodiment of the application provides a session establishment method and equipment, so that when a terminal switches a plurality of PDU sessions with the same DNN established in a 5G network to a PDN connection of a 4G network, the PDU sessions can be anchored to the same control plane function network element when being switched to the 4G, and each switched PDN connection has different APNs, thereby realizing the control of APN AMBR. The method comprises the following steps: the terminal sends a first request message for establishing a PDU session, wherein the first request message comprises a data network name DNN; the terminal receives a first response message, wherein the first response message comprises an Access Point Name (APN); and the terminal sends a second request message for establishing the PDN connection to a mobile management network element, wherein the second request message comprises the APN.

Description

Session establishment method and device

Technical Field

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

Background

With the rapid development of wireless communication technology, Fifth Generation (5G) mobile communication technology has come. At the initial stage of network deployment, due to insufficient coverage of the 5G network, when the location of a User Equipment (UE) changes, handover of the UE between the 5G network and a fourth Generation (4G) network may occur.

Establishing a Packet Data Network (PDN) connection in a 4G network requires an Access Point Name (APN) parameter, while creating a Protocol Data Unit (PDU) session in 5G requires a Data Network Name (DNN) and single network slice selection assistance information (S-NSSAI). In existing standard protocols, APN and DNN are equivalent.

In the research process, the applicant finds that, when the UE switches to the PDN connection in 4G in the 5G session established by the UE in the prior art, the following problems may exist:

the UE may have multiple PDU sessions established in 5G and these PDU sessions may use the same DNN. And 5G does not specify that sessions of the same DNN must select the same session management device, these multiple PDU sessions with the same DNN may be anchored on different session management devices.

However, in 4G, in order to perform APN Aggregated Maximum Bit Rate (AMBR) control, multiple PDN connections of one same APN are required to be anchored only on one session management device. If a plurality of PDU sessions with the same DNN in 5G are switched to a plurality of PDN connections with the same APN in 4G, if the session continuity is satisfied, it will result in that the APN AMBR in 4G cannot be controlled.

Disclosure of Invention

The embodiment of the application provides a session establishment method, a device and a system, so that when a terminal switches a plurality of PDU sessions with the same DNN established in a 5G network to a PDN connection of a 4G network, the PDU sessions can be anchored to a control plane function network element which is the same as the PDU session when being switched to the 4G, and each switched PDN connection has different APNs, thereby realizing the control of APN AMBR.

In order to achieve the above purpose, the embodiments of the present application provide the following technical solutions:

in a first aspect, a session establishment method is provided, where the method includes: a terminal sends a first request message for establishing a Packet Data Unit (PDU) session, wherein the first request message comprises a Data Network Name (DNN); the terminal receives a first response message, wherein the first response message comprises an access point name APN corresponding to the PDU session; the APN is unique within the range of the terminal and can be used for uniquely identifying the PDU session of the terminal; and the terminal sends a second request message for establishing a Packet Data Network (PDN) connection to a mobile management network element, wherein the second request message comprises the APN. Based on the session establishment method provided by the embodiment of the application, in the process of establishing the PDU session by the terminal, the terminal can obtain a unique APN within the range of the terminal from the network side. That is to say, based on this scheme, when a terminal establishes multiple PDU sessions with the same DNN, these PDU sessions may be switched to PDN connections with different APNs, and as APNs corresponding to the switched PDN connections are different, the problem that APN AMBR cannot be controlled in the prior art can also be solved.

In one possible design, the APN is carried in a protocol configuration item PCO. That is to say, a control plane function network element on the network side may send the APN to the terminal through a PCO message, so that other intermediate devices in the network may avoid analyzing the information (for example, an MME in a 4G network), thereby reducing updating of devices in the network due to the scheme in the present application as much as possible.

In one possible design, the first request message further includes a PDU session identifier of the PDU session, and the first response message further includes the PDU session identifier; before the sending of the second request message for establishing the PDN connection to the mobility management network element, the method further includes: and saving the APN into a session context indicated by the PDU session identification.

In one possible design, the method further includes: and sending indication information, wherein the indication information is used for indicating that all PDU sessions established by the terminal or a specific PDU session needs to be switched to the 4G network subsequently. The indication information can be sent to the SMF + PGW-C by the terminal or a third party application server in the session establishment process, and when the PDU session established by the terminal request meets the indication information, the process of the scheme of the application is executed; otherwise, the establishment procedure of the PDU session is performed according to the prior art. For example, the indication information may include at least one of an identity of the terminal, a Session and Service Continuity (SSC) pattern corresponding to the PDU session, and S-NSSAI, DNN corresponding to the PDU session. Or the indication information may also be sent to the SMF + PGW-C in a PDU session establishment request carried by the terminal. At this time, the indication information may be, for example, an indication bit, and when the indication bit sets a bit "1", it indicates that the PDU session requested to be established needs to be subsequently switched to the 4G network; when the indication bit is set to "0" or the indication bit is not present, it indicates that the PDU session requested to be established does not need to be subsequently switched into the 4G network.

In one possible design, the second request message is used to request establishment of a PDN connection, and may specifically be an attach request or a PDN connection establishment request.

In a second aspect, a session establishment method is provided, and the method includes: a control plane function network element receives a first request message for requesting to establish a Packet Data Unit (PDU) session from a terminal; wherein the first request message comprises a data network name DNN; and acquiring an Access Point Name (APN) corresponding to the PDU session, wherein the APN is unique within the range of the terminal and is used for uniquely identifying the PDU session of the terminal. Based on the session establishment method provided by the embodiment of the application, in the process of establishing the PDU session by the terminal, the terminal can obtain a unique APN within the range of the terminal from the network side. That is to say, based on this scheme, when a terminal establishes multiple PDU sessions with the same DNN, these PDU sessions may be switched to PDN connections with different APNs, and as APNs corresponding to the switched PDN connections are different, the problem that APN AMBR cannot be controlled in the prior art can also be solved.

In one possible design, the method further includes: and sending a first response message to the terminal, wherein the first response message comprises the APN. After the control plane functional network element obtains the APN, the obtained APN may be sent to the terminal through a PCO message in a PDU session establishment response, so that the terminal may store the APN in a session context.

In one possible design, the APN may be determined by modifying the DNN by a value-unique parameter within the terminal range. For example, the control plane function network element may modify the DNN according to one or more of the parameters of the S-NSSAI, the PDU session ID, the identity of the control plane function network element itself, and the random number in the PDU session establishment request, thereby dynamically generating the APN. In particular, the benefit of using random numbers for modification is that the network sensitive information can be hidden, and in order to ensure the uniqueness of the random numbers, S-NSSAI, PDU session ID, SMF + PGW-C ID, and other uniqueness parameters such as time parameters can be used as the input of the random number generation function when generating the random numbers. After generating the random number, the control plane function network element may use the random number as a decoration of the DNN. In TS23.003 with APN modification method, can refer to the APN modification method to modify DNN. By adopting the method, DNN in the PDU session requested to be established by the terminal can be mapped to the unique APN within the range of the terminal, so that when the terminal establishes different PDU sessions specifically having the same DNN, the parameters for modifying the DNN are different, and the generated APN is different. Thereby ensuring that different PDU sessions of the same DNN have different APNs when switched to a PDN connection in the 4G network.

In one possible design, the control plane function network element further obtains subscription data for the APN. For example, the control plane function network element may generate the subscription data of the APN according to the subscription data of the DNN and send the generated subscription data of the APN to the user data management network element, or the user data management network element may generate the subscription data of the APN according to the subscription data of the DNN and send the subscription data of the APN to the control plane function network element.

In a third aspect, a session establishment method is provided, where the method includes: a user data management network element receives a first message sent by a control plane function network element, wherein the first message comprises DNN; and acquiring an access point name APN corresponding to the PDU session, wherein the APN is unique within the terminal range and is used for uniquely identifying the PDU session.

In one possible design, the APN is determined by modifying the DNN by a numerically unique parameter within the terminal range. For example, the first message further includes a PDU session identifier of the PDU session and/or single network slice selection assistance information S-NSSAI, and the acquiring an access point name APN corresponding to the PDU session specifically includes: and the user data management network element generates the APN according to one or more modified DNNs in the parameters of the S-NSSAI, the PDU session ID, the identification of the control plane function network element and the random number in the PDU session establishment request. In particular, the benefit of using random numbers for modification is that the network sensitive information can be hidden, and in order to ensure the uniqueness of the random numbers, S-NSSAI, PDU session ID, SMF + PGW-C ID, and other uniqueness parameters such as time parameters can be used as the input of the random number generation function when generating the random numbers. After generating the random number, the user data managing network element may use the random number as a modification of the DNN. In TS23.003 with APN modification method, can refer to the APN modification method to modify DNN. By adopting the method, DNN in the PDU session requested to be established by the terminal can be mapped to the unique APN within the range of the terminal, so that when the terminal establishes different PDU sessions specifically having the same DNN, the parameters for modifying the DNN are different, and the generated APN is different. Thereby ensuring that different PDU sessions of the same DNN have different APNs when switched to a PDN connection in the 4G network.

In one possible design, the subscriber data management network element obtains subscription data for the APN. For example, the user data management network element may generate subscription data of the APN according to the subscription data of the DNN, or receive the subscription data of the APN from the control plane function network element, and send the APN subscription data to the mobile management network element (MME), so that the mobile management network element may authorize the establishment request of the corresponding PDN connection according to the subscription data of the APN. And when the user data management network element generates the subscription data of the APN according to the subscription data of the DNN, the first message also comprises S-NSSAI, and the user data management network element acquires the subscription data of the DNN corresponding to the PDU session according to the S-NSSAI and the DNN.

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

In a fifth aspect, a terminal is provided, including: a processor and a memory; the memory is configured to store computer executable instructions, and when the terminal runs, the processor executes the computer executable instructions stored in the memory, so as to enable the terminal to perform the session establishment method according to any one of the above first aspects.

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 establishment method of any one of the above first aspects.

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

In an eighth aspect, a chip system is provided, which includes a processor for enabling a terminal to implement the functions recited in the above aspects. In one possible design, the system-on-chip further includes a memory for storing program instructions and data necessary for the terminal. The chip system may be constituted by a chip, or may include a chip and other discrete devices.

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

A ninth aspect provides a control plane functional network element having the function of implementing the method of the second aspect. The function can be realized by hardware, and can also be realized by executing corresponding software by hardware. The hardware or software includes one or more modules corresponding to the functions described above.

In a tenth aspect, there is provided a control plane functional network element, including: a processor and a memory; the memory is configured to store computer executable instructions, and when the control plane function network element is running, the processor executes the computer executable instructions stored by the memory, so as to cause the control plane function network element to perform the session establishment method according to any one of the above second aspects.

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

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

In a thirteenth aspect, a chip system is provided, where the chip system includes a processor configured to support a control plane function network element side to implement the functions in the foregoing aspects. In one possible design, the system-on-chip further includes a memory for storing program instructions and data necessary for the control plane functional network element. The chip system may be constituted by a chip, or may include a chip and other discrete devices.

The technical effects brought by any one of the design manners of the ninth aspect to the thirteenth aspect can be referred to the technical effects brought by different design manners of the second aspect, and are not described herein again.

In a fourteenth aspect, there is provided a user data management network element having a function of implementing the method of the third 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 fifteenth aspect, there is provided a user data management network element, comprising: a processor and a memory; the memory is configured to store computer executable instructions, and when the user data management network element is running, the processor executes the computer executable instructions stored by the memory, so as to cause the user data management network element to perform the session establishment method according to any one of the third aspects.

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

A seventeenth aspect provides a computer program product comprising instructions which, when run on a computer, causes the computer to perform the session establishment method of any of the third aspects above.

In an eighteenth aspect, a chip system is provided, which includes a processor for supporting a user data management network element to implement the functions referred to in the above aspects. In one possible design, the system-on-chip further includes a memory for storing program instructions and data necessary for the second mobility management entity. The chip system may be constituted by a chip, or may include a chip and other discrete devices.

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

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 hardware structure diagram of a communication device according to an embodiment of the present application;

fig. 3 is a first flowchart illustrating a session establishment method according to an embodiment of the present application;

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

FIG. 5 is a schematic structural diagram of an apparatus according to an embodiment of the present disclosure;

fig. 6 is a schematic structural diagram of a control plane functional network element according to an embodiment of the present application;

fig. 7 is a schematic structural diagram of a user data 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.

An embodiment of the present invention provides a method for mobility management, which may be applied to a 4G network and 5G network interworking architecture system 100 shown in fig. 1, and as shown in fig. 1, the method includes a User Plane Function (UPF) entity, a PDN gateway user plane function (PGW-U) entity, a Session Management Function (SMF) entity, a PDN gateway control plane function (PDN gateway control plane function, PGW-C) entity, a Policy Control Function (PCF) entity, a policy and charging rules function (policy and charging rules function, PCRF) entity, a home subscriber server (home subscriber server, HSS) + a unified data management (unified data management, data) entity, where the User Plane Function (UPF) entity and the PDN gateway user plane function (PGW-U) entity are shared by the 4G network and the 5G network. 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. The term "co-located" refers to the function of two entities in the same device. In the embodiment of the present application, for convenience of description, an HSS + UDM entity is referred to as a user data management network element, and a PGW-C entity + SMF entity is referred to as a control plane function network element, which is described herein in a unified manner and will not be described in detail below. Of course, the combined network device may also use other names, and this embodiment of the present application is not limited to this specifically.

In addition, as shown in fig. 1, the interworking architecture between the 4G network and the 5G network may further include a Mobility Management Entity (MME) and a Serving Gateway (SGW), and an Access and Mobility Management Function (AMF) Entity in the 5G network.

The terminal is accessed to the 4G network through evolved universal terrestrial radio access network (E-UTRAN) equipment, and the terminal is accessed to the 5G network through next generation radio access network (NG-RAN) equipment. E-UTRAN equipment communicates with MME through S1-MME interface, E-UTRAN equipment communicates with SGW through S1-U interface, MME communicates with SGW through S11 interface, MME communicates with user data management entity through S6a interface, MME communicates with AMF entity through N26 interface, SGW communicates with PGW-U entity + UPF entity through S5-U interface, SGW communicates with PGW-C entity + SMF entity through S5-C interface, PGW-U entity + UPF entity communicates with NG-RAN equipment through N3 interface, PGW-U entity + UPF entity communicates with PGW-C entity + SMF entity through N4 interface, PGW-C entity + SMF entity communicates with PCRF entity + PCF entity through N7 interface, HSS + UDM entity communicates with PGW-C entity + SMF entity through N10 interface, HSS + UDM entity communicates with AMF entity through N8 interface, the PCRF entity and the PCF entity communicate with the AMF entity through an N15 interface, the PGW-C entity and the SMF entity communicate with the AMF entity through an N11 interface, the AMF entity communicates with NG-RAN equipment through an N2 interface, and the AMF entity communicates with a terminal through an N1 interface. The N26 interface between the MME and the AMF in the interworking architecture may not exist in some scenarios, and the N26 interface may be used for terminal context transfer and handover procedures. The present application will describe the related possible implementations respectively for whether there is an N26 interface between the MME and the AMF.

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

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

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

APN：

In a 4G network, a terminal may provide an APN to an MME when initiating packet traffic. The MME may perform domain name resolution through a Domain Name Server (DNS) according to the APN provided by the terminal, so as to obtain an address (e.g., an internet protocol address) of the session management network element, and thus access the terminal to the PDN corresponding to the APN.

DNN：

In a 5G network, the terminal may provide S-NSSAI and DNN to the AMF when initiating a PDU session setup. The AMF determines the address of the session management network element based on the S-NSSAI, DNN, and other information (e.g., subscription information of the terminal, local operator policy, etc.). The determined session management network element establishes a PDU session for the terminal based on the S-NSSAI and the DNN.

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

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

As shown in fig. 2, the nodes shown in fig. 1, such as a terminal, an MME, an AMF, an SMF entity + PGW-C entity, an E-UTRAN or an NG-RAN, etc., may be implemented in the manner of the communication device (or system) in fig. 2.

Fig. 2 is a schematic diagram illustrating a hardware structure of a communication device according to an embodiment of the present application. The communication device 200 includes at least one processor 201, communication lines 202, memory 203, and at least one communication interface 204.

The processor 201 may be a general 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 invention.

The communication link 202 may include a path for transmitting information between the aforementioned components.

The communication interface 204 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 203 may be a read-only memory (ROM) or other type of static storage device that can store static information and instructions, a Random Access Memory (RAM) or other type of dynamic storage device that can 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, but is not limited to these. The memory may be separate and coupled to the processor via communication line 202. The memory may also be integral to the processor.

The memory 203 is used for storing computer execution instructions for executing the scheme of the application, and is controlled by the processor 201 to execute. The processor 201 is configured to execute computer-executable instructions stored in the memory 203, so as to implement the session establishment method provided by the following embodiments of 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 201 may include one or more CPUs such as CPU0 and CPU1 in fig. 2, for example, as one embodiment.

In particular implementations, communication device 200 may include multiple processors, such as processor 201 and processor 208 in fig. 2, 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 200 may also include an output device 205 and an input device 206, as one embodiment. The output device 205 is in communication with the processor 201 and may display information in a variety of ways. For example, the output device 205 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 206 may be a mouse, a keyboard, a touch screen device, or a sensing device, among others.

The communication device 200 described above may be a general purpose device or a special purpose device. In a specific implementation, the communication device 200 may be a desktop, a laptop, a web server, a Personal Digital Assistant (PDA), a mobile phone, a tablet, a wireless terminal device, an embedded device, or a device with a similar structure as in fig. 2. The embodiment of the present application does not limit the type of the communication device 200.

The session establishment method provided in the embodiment of the present application will be specifically described below with reference to fig. 1 and fig. 2.

As shown in fig. 3, a session establishment method provided in the embodiment of the present application is provided. In this embodiment, the terminal establishes a PDU session in the 5G network first, and subsequently, the terminal needs to access the 4G network because the terminal location moves out of the 5G service range or other reasons. Specifically, when a terminal requests to establish a PDU session, a control plane function network element or a user data management network element maps a DNN carried in the PDU session establishment request to an APN unique to the terminal, and keeps the mapped APN in the context of the terminal. In addition, the control plane function network element also needs to send the mapped APN to the terminal (for example, the mapped APN may be carried in a Protocol Configuration Option (PCO) message and sent to the terminal). When the terminal needs to be switched from 5G to 4G, the mapped APN is carried, then the MME acquires the context of the terminal from the user data management network element, and therefore the control plane function network element serving the terminal is determined according to the carried APN and the acquired context, and the effect that when the 5G PDU session is switched to 4G, the PDU session is anchored to the control plane function network element which is the same as the original PDU session is achieved. When the terminal establishes a plurality of PDU sessions with the same DNN in the 5G network, the method can ensure that each PDU session can be anchored to a control plane function network element which is the same as the original PDU session when being switched to the 4G network, and each switched PDN connection has different APNs, thereby realizing the control of APN AMBR. The method specifically comprises the following steps:

step 301, the terminal sends a PDU session establishment request to a mobility management network element in the first network.

The mobility management element in the first network may be, for example, the AMF shown in fig. 3, which is hereinafter substituted for the mobility management element in the first network. The PDU Session establishment request comprises S-NSSAI, DNN and PDU Session identification (PDU Session ID), and is used for requesting the network side to establish a PDU Session between the terminal and the data network indicated by DNN through a network slice example indicated by S-NSSAI.

It should be noted that, a terminal may establish multiple PDU sessions in a 5G network, and the multiple PDU sessions may correspond to the same DNN and are served by the same or different control plane function network elements (i.e. SMF + PGW-C in this embodiment), which is not limited in this embodiment of the present application. For convenience of description, the embodiments of the present application only take the case that a terminal establishes a PDU session through a control plane function network element as an example.

Step 302, the AMF receives a PDU session establishment request sent by the terminal, and sends the session establishment request to the SMF + PGW-C.

The Session establishment request comprises S-NSSAI, DNN and PDU Session ID carried in the PDU Session establishment request.

It should be noted that how the AMF determines the address of the SMF + PGW-C is the prior art, the embodiment of the present invention is not limited, and the related method may refer to the existing standard.

Step 303, SMF + PGW-C performs the mapping operation.

The mapping operation performed by the SMF + PGW-C includes mapping DNN in the session establishment request to an APN unique to the terminal, and optionally, generating subscription data corresponding to the APN. A method for generating signing data corresponding to APN is to map QoS parameter corresponding to PDU session to QoS parameter corresponding to PDN connection corresponding to PDU session switching to 4G, for example, to map session AMBR corresponding to PDU session to APN AMBR corresponding to PDN connection, map ARP corresponding to PDU session to ARP corresponding to PDN connection, etc., and to store the mapped QoS parameter as signing data of mapped APN in HSS + UDM, so that when terminal switches from 5G to 4G, HSS + UDM sends the data of mapped signing APN to corresponding MME. Or, the DNN subscription data is directly mapped to the corresponding APN subscription data, and the mapped APN subscription data is stored in the HSS + UDM, so that when the terminal is switched from 5G to 4G, the HSS + UDM sends the mapped APN subscription data to the corresponding MME.

The method for the SMF + PGW-C to map the DNN in the session establishment request to an APN unique to the terminal may include multiple methods, for example:

(1) the SMF + PGW-C may map the DNN to an APN unique to the terminal according to a mapping relationship between the locally preconfigured DNN and the APN. For example, the SMF + PGW-C local may be pre-configured with the mapping relationship between DNN, S-NSSAI and APN (as shown in Table 1) or the mapping relationship between DNN, S-NSSAI, SMF + PGW-C ID and APN (as shown in Table 2).

TABLE 1

DNN	S-NSSAI	APN
			DNN1	S-NSSAI1	APN1
DNN1	S-NSSAI2	APN2
			DNN2	S-NSSAI1	APN3
DNN2	S-NSSAI2	APN4

TABLE 2

In a possible implementation manner, when a UE establishes only one PDU session in a network slice instance corresponding to an S-NSSAI for one DNN, the mapping relationship shown in table 1 may be adopted to map the DNN to an APN unique to the terminal. When the UE establishes multiple PDU sessions of the same DNN in one or multiple network slices corresponding to one S-NSSAI, the mapping relationship in table 2 may be used to map the DNN to an APN unique to the terminal.

It should be noted that the mapping relationship in table 1 and table 2 is only an example, and may be implemented by other mapping relationships, which is not limited in the embodiment of the present invention.

(2) The SMF + PGW-C may map the DNN to an APN unique to the terminal according to a preset rule. For example, the DNN may be modified using parameters unique to the terminal to generate the APN. One possible implementation is: the SMF + PGW-C modifies the DNN according to one or more parameters of S-NSSAI, PDU session ID, self identification of the SMF + PGW-C and random number in the PDU session establishment request, thereby dynamically generating APN, such as DNN @ PDU session ID1 ═ APN1, DNN @ PDU session ID2 ═ APN2, DNN @ PDU session ID3 ═ APN 3. The benefit of using random numbers for modification is that network sensitive information, such as SMF + PGW-C ID, can be hidden. The SMF + PGW-C firstly generates a random number, and in order to ensure the uniqueness of the random number, the S-NSSAI, the PDU session ID, the SMF + PGW-C ID and other uniqueness parameters such as time parameters and the like can be used as the input of the random number generation function when the random number is generated. In the prior art, a plurality of methods can ensure the uniqueness of the random number, and the embodiment of the invention does not make provisions. After the random number is generated, SMF + PGW-C may use the random number as a modification of DNN, for example, DNN — internet, where the random number 1234, DNN may be modified to internet.1234, or internet @ 1234. In TS23.003 with APN modification method, can refer to the APN modification method to modify DNN. In addition, it should be noted that the APN generated by mapping may also be independent of the DNN, for example, the SMF + PGW-C may generate a random number as the mapped APN according to the PDU session ID and other unique parameters such as time parameter as the input of the random number generation function.

In some scenarios, the methods (1) and (2) above may ensure that the APN generated by mapping is not repeated in all PDU sessions established by the terminal. It should be noted that, in a specific implementation, (1) and (2) may also be combined to implement mapping of DNN to APN unique to the terminal. For example, the SMF + PGW-C may determine a temporary APN according to table 1, and then modify the temporary APN with its own SMF + PGW-C ID to obtain the mapped APN.

On the other hand, the SMF + PGW-C may also map the QoS parameter corresponding to the PDU session to the QoS parameter corresponding to the PDN connection after the session is switched to 4G, such as mapping session AMBR to APN AMBR corresponding to the PDN connection, mapping Allocation Retention Priority (ARP) of the PDU session to ARP of the PDN connection, and the like. One method to map the Session AMBR to the APN AMBR is to set the APN AMBR equal to the Session AMBR. Other mapping methods may be used in specific implementation, for example, the APN AMBR is set to be smaller than the Session AMBR, which is not specified in the embodiment of the present invention. Similarly, a method for mapping the ARP corresponding to the PDU session to the ARP corresponding to the PDN connection is to set the ARP corresponding to the PDN connection to the ARP corresponding to the PDU session, and other mapping methods may be used in specific implementation, for example, the ARP corresponding to the PDN connection is set to be greater than or less than the ARP corresponding to the PDU session.

Specifically, the SMF + PGW-C further stores the mapped APN and the QoS parameter (optional) association corresponding to the mapped PDN connection in the context of the terminal.

The method further includes that the SMF + PGW-C returns a session establishment response to the AMF, where the session establishment response includes information (such as an identifier or an address) of the control plane function network element.

Step 304, SMF + PGW-C sends a registration request to HSS + UDM.

The registration request includes information of the SMF + PGW-C (for example, an ID or address information of the SMF + PGW-C), and the mapped APN, so that the HSS + UDM stores the information of the SMF + PGW-C and the mapped APN association in related information (for example, a session context) of the terminal. If the SMF + PGW-C generates the subscription data for the APN, the registration request message further includes the subscription data for the APN, so that the HSS + UDM stores the subscription data for the APN in the relevant information (e.g., the subscription data or the session context corresponding to the terminal) of the terminal. It should be noted that, in the embodiment of the present application, how the HSS + UDM stores the relevant information is not limited.

It should be noted that the mapping operation of DNN to APN performed by SMF + PGW-C and the mapping operation of QoS parameters corresponding to PDU sessions to QoS parameters corresponding to PDN connections may also be performed by HSS + UDM. Specifically, when the SMF + PGW-C performs the above mapping operation and is executed by the HSS + UDM, steps 303 and 304 may be replaced by steps a to C as follows:

step A, SMF + PGW-C sends a registration request to HSS + UDM;

the registration request includes the identifier of the terminal, the information of SMF + PGW-C, the DNN in the session establishment request received in step 302, and optional S-NSSAI and other information.

Step B, HSS + UDM receives the registration request sent by SMF + PGW-C and performs the mapping operation.

A specific method for the HSS + UDM to perform the mapping operation is the same as the method for the SMF + PGW-C to perform the mapping in step 303, and a specific process refers to the relevant description in step 303, and is different from step 303 in that when the HSS + UDM acquires the subscription data of the APN, the HSS + UDM first acquires the subscription data of the DNN corresponding to the PDU session according to the S-NSSAI and the DNN corresponding to the session, and then maps the relevant parameters in the subscription data of the DNN corresponding to the S-NSSAI and the DNN to the relevant parameters in the subscription data of the APN, and the subscription data of the DNN includes APN AMBR, ARP, and the like.

After the HSS + UDM performs the mapping operation, the information of the SMF + PGW-C, the mapped APN, and the subscription data corresponding to the mapped APN are stored in the relevant information of the terminal in an associated manner, for example, the information of the SMF + PGW-C and the mapped APN may be stored in the session context of the terminal, and the subscription data corresponding to the mapped APN may be stored in the subscription data of the UE.

Step C, HSS + UDM sends a registration response to SMF + PGW-C.

And after receiving the registration response sent by the HSS + UDM, the SMF + PGW-C stores the mapped APN and the subscription association of the mapped APN into the relevant information of the terminal.

It should be noted that the mapping may also be performed separately in the SMF + PGW-C and the HSS + UDM, for example, the SMF + PGW-C is responsible for mapping DNN to APN, and the HSS + UDM is responsible for generating subscription data for APN. The embodiments of the present invention are not specified.

Optionally, before performing the mapping operation, the SMF + PGW-C or HSS + UDM further receives indication information from the terminal or the third party application server, where the indication information is used to indicate that all PDU sessions established by the terminal or a specific PDU session needs to be subsequently switched to the 4G network.

One possible implementation manner is that the indication information may be sent to the SMF + PGW-C by the terminal or the third party application server in the session establishment process, and when the PDU session requested to be established by the terminal in step 301 meets the indication information, the process of the embodiment of the present application is executed; otherwise, the establishment procedure of the PDU session is performed according to the prior art. For example, the indication information may include at least one of an identity of the terminal, a Session and Service Continuity (SSC) pattern corresponding to the PDU session, and S-NSSAI, DNN corresponding to the PDU session. For example, when the SMF + PGW-C receives a terminal request indicated by the terminal identifier to establish a PDU session to the data network indicated by the DNN, the SMF + PGW-C determines that the PDU session needs to be subsequently switched to the 4G network, or when the SMF + PGW-C determines that the established PDU session is SSC mode 1, the SMF + PGW-C may determine that the PDU session needs to be subsequently switched to the 4G network according to the information, or the SMF + PGW-C determines that the PDU session needs to be subsequently switched to the 4G network according to the S-NSSAI corresponding to the session. Or the indication information may also be carried by the terminal in the PDU session establishment request in step 301 and sent to the SMF + PGW-C. At this time, the indication information may be, for example, an indication bit, and when the indication bit sets a bit "1", it indicates that the PDU session requested to be established needs to be subsequently switched to the 4G network; when the indication bit is set to "0" or the indication bit is not present, it indicates that the PDU session requested to be established does not need to be subsequently switched into the 4G network.

And 305, establishing a subsequent PDU session.

In step 302, the SMF + PGW-C receives a session establishment request from the AMF, and establishes a PDU session for the terminal based on the S-NSSAI and DNN in the session establishment request. The process of establishing the PDU session may refer to the existing flow, which is not described herein.

Steps 301 to 305 are used to implement a procedure of establishing a PDU session in a terminal in a 5G network, and in this procedure, in the embodiment of the present application, a mapping that DNN in the PDU session is mapped to an APN whose terminal range name is not overlapped is additionally implemented.

And step 306, the SMF + PGW-C sends the mapped APN to the terminal.

Specifically, the SMF + PGW-C may carry the mapped APN in a PCO message and send the PCO message to the terminal. One possible implementation is that the PCO message may be carried in a PDU session setup response. And sending the mapped APN to the terminal by adopting a PCO message, thereby avoiding extra burden caused by analyzing the cell by a network element between the SMF + PGW-C and the terminal in the message transmission process.

And after the terminal receives the mapped APN, storing the mapped APN into the session context. Specifically, in step 306, the SMF + PGW-C further sends the PDU Session ID to the terminal, and after receiving the mapped APN and PDU Session ID, the terminal stores the mapped APN in the corresponding Session context.

Step 307, the terminal sends an attach request or a PDN connection establishment request to the MME, so that the MME receives the attach request or the PDN connection establishment request.

Wherein, the attach request or the PDN connection establishment request carries the mapped APN received in step 306, and the mapped APN is also generated by the terminal in the PDU session establishment process. It should be noted that, in this step, a situation that the terminal sends the PDN connection establishment request may occur is that the UE has completed the attach procedure, but still needs to switch the PDU session, and immediately initiates a corresponding PDN connection establishment procedure for the PDU session after completing the attach procedure.

Specifically, step 307 may occur when the location of the terminal moves, for example, moves from 5G coverage to a place with only 4G coverage, or when the terminal changes from 5G network access to data network to 4G network access to data network for some other reason.

Further, when the step 307 is an attach request, the attach request further includes an identifier of the terminal. It should be noted that the identifier of the terminal here may be information for characterizing the UE, such as an International Mobile equipment Identity (IMSI), or may be a temporary identifier of the UE, such as a 4G GUTI mapped from a 5G Globally Unique Temporary Identifier (GUTI). The embodiment of the present application does not limit the specific form of the identifier of the terminal.

When the step 307 is an attach request, step 308 is executed to obtain the relevant information of the terminal from the HSS + UDM; if the PDN connection establishment request is received in step 307, it can be understood that in the attach procedure before the PDN connection establishment request, the MME has already obtained the relevant information of the terminal from the HSS + UDM, so step 309 is directly performed.

And step 308, acquiring relevant information of the terminal from the HSS + UDM.

Specifically, the terminal sends a location update request to the HSS + UDM, where the location update request carries an identifier of the terminal. And the HSS + UDM acquires the context of the terminal according to the identifier of the terminal, for example, the context includes the information of the SMF + PGW-C, the mapped APN, the subscription data of the mapped APN and the like. It should be noted that the context of the terminal may be stored in association, for example, a plurality of session information and corresponding subscription data may be stored in the context of the terminal, and one possible implementation manner is shown in table 3:

the subscription data of the terminal may be as shown in table 4:

identification of terminal	APN of subscription
		UE
1	APN1
		UE
1	APN 2
		UE 2	APN 4

The UE is configured to refer to an identifier of a terminal, and it should be noted that the APN subscription data in table 3 may also be stored in the subscription data in the UE. After the HSS + UDM receives the location update request from the MME in step 308, the context corresponding to the terminal is obtained according to the terminal identifier therein. For example, if the identifier of the terminal, which is received by the HSS + UDM and carried by the location update request generated by the MME, is UE1, the HSS + UDM obtains the session context and subscription information related to UE1, such as (the subscription data of APN1, SMF + PGW-C1, APN1, APN 1), (APN2, SMF + PGW-C1, APN2, and APN 2). And the HSS + UDM sends the acquired session context and subscription information related to the UE1 to the MME.

Step 309, the MME sends a session update request to SMF + PGW-C.

Specifically, the MME determines the identifier of the anchored SMF + PGW-C according to the mapped APN received from the terminal, and the session context and subscription data of the terminal acquired from the HSS + UDM, and sends a session update request to the determined SMF + PGW-C. Wherein the session update request includes the mapped APN received from the terminal.

If step 307 is an attach request, the MME selects a serving gateway (S-GW) according to the UE location. The MME sends a session update request to the anchored SMF + PGW-C via the S-GW. The session update request carries downlink tunnel information corresponding to the session assigned by the S-GW. Optionally, the MME sends the QoS parameters in the APN subscription data obtained in step 308, such as APN AMBR, to the anchored SMF + PGW-C as well. And the anchored SMF + PGW-C searches the session context of the terminal according to the received APN, and acquires the user plane tunnel information corresponding to the session, including the IP address of the PGW-U + UPF and the uplink tunnel information. The anchored SMF + PGW-C informs the PGW-C + UPF corresponding to the session of the downlink tunnel information of the S-GW (this step is prior art and is not shown in the figure).

In a possible implementation manner, before the MME sends the session update request to the SMF + PGW-C, the MME further includes an MME determining whether the terminal has a right to update the session. When the MME determines that the mapped APN sent by the terminal is signed according to the subscription information returned by the HSS and the UDM, the MME determines that the terminal has the authority of session update, and executes step 309 to send a session update request to the SMF and the PGW-C; and when the MME determines that the APN after mapping sent by the terminal is not signed or the subscription information returned by the HSS and the UDM does not include the APN after mapping according to the subscription information returned by the HSS and the UDM, the MME determines that the terminal does not have the authority of session updating, and the process is ended.

And step 310, the SMF + PGW-C returns a session establishment response to the MME.

And the SMF + PGW-C sends the uplink tunnel information of the PGW-U + UPF corresponding to the session to the S-GW. And the S-GW replies a session establishment response to the MME and sends uplink tunnel information of the S-GW allocated by the S-GW to the MME.

Step 311, the subsequent process.

And when the MME receives a session establishment response sent by the SMF + PGW-C, entering a subsequent flow to complete the establishment of the PDN connection.

In a possible implementation manner, if the step 307 is an attach request, the MME processes a subsequent attach procedure, including notifying the base station to create air interface resources for the session, establishing a tunnel between the base station and the S-GW, and notifying the terminal of an attach result. If step 307 is a PDN connection establishment request, the subsequent procedure is a PDN connection establishment procedure, which also includes notifying the base station to create air interface resources for the session, establishing a tunnel between the base station and the S-GW, and notifying the terminal of the PDN connection establishment result. The subsequent process may refer to the existing process, and is not described herein.

Based on the session establishment method provided by the embodiment of the application, in the process of establishing the PDU session by the terminal, the SMF + PGW-C or HSS + UDM is required to generate a unique temporary APN relative to the terminal according to DNN, generate subscription data corresponding to the mapped APN according to the subscription data corresponding to DNN, and store the relevant information into the SMF + PGW-C or HSS + UDM. When the terminal switches a plurality of PDU sessions with the same DNN established in the 5G network to the PDN connection of the 4G network, the terminal not only ensures that each PDU session can be anchored to the same control plane functional network element when being switched to the 4G network, but also ensures that each switched PDN connection has different APNs, thereby realizing the control of APN AMBR. Furthermore, this solution does not require changes to the existing MME.

The actions of the control plane function network element (SMF + PGW-C) and the user data management network element (HSS + UDM) in steps 301 to 311 may be executed by the processor 201 in the communication device 200 shown in fig. 2 calling the application program code stored in the memory 203, which is not limited in this embodiment of the present application.

It should be noted that the embodiment shown in fig. 3 is applicable to a scenario where an N26 interface does not exist between the mobility management element AMF in the first network and the mobility management element MME in the second network, and when an N26 interface exists between the AMF and the MME, the method shown in fig. 4 may be adopted. As shown in fig. 4, a session establishment method provided in the embodiment of the present application includes the following steps:

the steps 401 and 406 and the synchronization steps 301 and 306 may refer to the embodiment shown in fig. 3, and are not described herein again.

When the terminal is in IDLE (IDLE) state, execute step 407-:

step 407, the terminal sends a tracking area update request to a mobility management network element (e.g. MME) of the second network.

Wherein, the tracking area updating request comprises 4G GUTI mapped by 5G-GUTI, and the specific mapping method refers to the prior art. The MME may determine the AMF previously serving the terminal according to the 4G GUTI.

Step 408, the MME requests the context of the terminal from the AMF.

Step 409, after receiving the request sent by the MME, the AMF obtains a PDU session context from the control plane function network element.

Wherein, the PDU session context includes the mapped APN and the information of the corresponding control plane function entity.

Step 410, the AMF sends the PDU session context to the MME.

In the subsequent flow, the MME performs session handover according to the context received from the AMF, step 411.

The subsequent process may refer to the existing process, and is not described herein.

When the terminal is in the Connected (Connected) state, steps 412 and 415 are executed:

in step 412, the base station sends a handover request to the AMF.

And when the base station determines that the terminal needs to be switched to the 4G, the base station sends an HO request to the AMF.

Step 413, synchronization step 409

Step 414, the AMF sends a redirection Request (Relocation Request) to the MME, and in this message, the AMF sends the session context to the MME.

Step 415, the subsequent flow.

The subsequent handover procedure can be referred to the related description in TS 23.502. In the handover process, the MME selects the SGW, and notifies the PGW-C + SMF to perform session update via the SGW.

Based on the session establishment method provided by the embodiment of the application, when the terminal switches a plurality of PDU sessions with the same DNN established in the 5G network to the PDN connection of the 4G network, the terminal not only ensures that each PDU session can be anchored to the same control plane function network element as the PDU session when being switched to the 4G, but also ensures that each switched PDN connection has different APNs, thereby realizing the control of APN AMBR.

The actions of the control plane function network element and the user data management network element in steps S401 to S415 may be executed by the processor 201 in the communication device 200 shown in fig. 2 calling the application program code stored in the memory 203, which is not 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 is to be understood that, in order to implement the above functions, the entities such as the terminal, the user data management network element, the control plane function network element, the AMF, and the MME include hardware structures and/or software modules corresponding to the respective functions. Those of skill in the art would readily appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as hardware or combinations of hardware and computer software. Whether a function is performed as hardware or computer software drives hardware depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.

In the embodiment of the present application, according to the above method example, the terminal, the user data management network element, and the control plane functional network element may be divided into functional modules, 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 where the functional modules are divided in an integrated manner, fig. 5 shows a schematic structural diagram of the apparatus according to the above-described embodiment. The device 50 may be a terminal, or may be a chip in the terminal, which is not specifically limited in this embodiment of the present application. As shown in fig. 5, the apparatus includes: a receiving module 501 and a sending module 502.

The sending module is configured to send a first request message for establishing a packet data unit PDU session, where the first request message includes a data network name DNN; the receiving module 501 is configured to receive a first response message, where the first response message includes an access point name APN; wherein the APN is determined by the DNN and is unique within the range of the terminal; wherein the APN may be carried in a protocol configuration item PCO; the sending module 502 is further configured to send a second request message for establishing a packet data network PDN connection to a mobility management network element, where the second request message includes the APN.

Optionally, the first request message further includes a PDU session identifier of the PDU session, and the first response message further includes the PDU session identifier; the terminal further comprises:

a saving module 503, configured to save the APN to the session context indicated by the PDU session identifier.

Optionally, the sending module is further configured to send indication information, where the indication information is used to indicate that all PDU sessions established by the terminal or a specific PDU session needs to be subsequently switched to the 4G network.

Optionally, the second request message is an attach request or a PDN connection establishment request.

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 this embodiment, the terminal 50 may be presented in a form of dividing each functional module in an integrated manner. A "module" as used herein may refer to an application-specific integrated circuit (ASIC), an electronic circuit, a processor and memory that execute one or more software or firmware programs, an integrated logic circuit, and/or other devices that provide the described functionality. In a simple embodiment, those skilled in the art will appreciate that the terminal 50 may take the form shown in FIG. 2.

For example, the processor 201 in fig. 2 may execute the instructions by calling a computer stored in the memory 203, so that the terminal 50 executes the session establishment method in the above method embodiment. Specifically, the functions/implementation processes of the receiving module 501, the sending module 502 and the saving module 503 in fig. 5 can be implemented by the processor 201 in fig. 2 calling a computer executing instruction stored in the memory 203.

Alternatively, when the apparatus 50 is a chip, the functions/implementation processes of the receiving module 501 and the sending module 502 may also be implemented by pins or circuits. Alternatively, when the apparatus 50 is a chip, the memory 203 may be a memory unit within the chip, such as a register, a cache, and the like. Of course, when the apparatus 50 is a terminal, the memory 203 may be a storage unit located outside a chip in the terminal, and this embodiment of the present application is not particularly limited thereto.

Since the terminal provided in the embodiment of the present application may be configured to execute the session establishment method, the technical effect obtained by the terminal may refer to the method embodiment, and will not be described herein again.

For example, in the case of dividing each functional module in an integrated manner, fig. 6 shows a structural schematic diagram of a control plane functional network element 60. The control plane functional network element 60 comprises: a receiving module 601 and an obtaining module 602. The receiving module 601 is configured to receive a first request message from a terminal for requesting establishment of a packet data unit PDU session; wherein the first request message comprises a data network name DNN; the obtaining module 602 is configured to obtain an access point name APN corresponding to the PDU session, where the APN is determined by the DNN and is unique within the terminal range.

The network element further comprises: a sending module 603; the sending module is configured to send a first response message to the terminal, where the first response message includes the APN. Optionally, the APN is carried in a protocol configuration item PCO.

Optionally, the APN is determined by modifying the DNN by a parameter unique to a value within the terminal range.

Optionally, the first request message further includes a PDU session identifier of the PDU session and/or single network slice selection auxiliary information S-NSSAI, and the obtaining module 602 is specifically configured to: generating the APN according to the PDU session identifier and/or the S-NSSAI and the DNN; the sending module is further configured to send the APN, the DNN, and the information of the control plane function network element to a user data management network element.

Optionally, the first request message further includes a PDU session identifier of the PDU session and/or single network slice selection auxiliary information S-NSSAI, and the obtaining module is specifically configured to: sending the PDU session identifier and/or the S-NSSAI and the DNN to a user data management network element; receiving the APN from the user data management network element.

Optionally, the receiving module 601 is further configured to receive a session update request from a mobility management network element, where the session update request includes the APN.

Optionally, the receiving module is further configured to receive a request for obtaining the session context of the terminal, where the request is sent by a mobility management network element; the sending module is further configured to send a session context response to the mobility management network element, where the session context response includes the APN and information of the control plane function network element.

Optionally, the obtaining unit 602 is further configured to obtain subscription data of the APN. For example, generating subscription data of the APN according to the subscription data of the DNN; the sending module 603 is further configured to send the subscription data of the APN to a user data management network element.

In the present embodiment, the control plane function network element 60 is presented in the form of dividing the respective functional modules 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, the control plane function network element 60 may take the form shown in fig. 2, as will be appreciated by those skilled in the art.

For example, the processor 201 in fig. 2 may cause the control plane function network element 60 to execute the session establishment method in the above-described method embodiment by calling a computer stored in the memory 203 to execute the instructions. Specifically, the functions/implementation processes of the receiving module 601, the obtaining module 602, and the sending module 603 in fig. 6 may be implemented by the processor 201 in fig. 2 calling a computer executing instruction stored in the memory 203.

Since the control plane functional network element provided in the embodiment of the present application may be configured to execute the session establishment method, the technical effect obtained by the control plane functional network element may refer to the method embodiment, and is not described herein again.

For example, in a case where the functional modules are divided in an integrated manner, fig. 7 shows a schematic structural diagram of a user data management network element. The subscriber data management network element 70 comprises: a receiving module 701 and an obtaining module 702. The receiving module 701 is configured to receive a first message from a control plane function network element; wherein the first message comprises a data network name DNN; the obtaining module 702 is configured to obtain an access point name APN corresponding to the PDU session, where the APN is determined by the DNN and is unique within the terminal range.

The APN is determined by modifying the DNN by a parameter with a value unique within the terminal range. For example, the first message further includes a PDU session identifier of the PDU session and/or single network slice selection assistance information S-NSSAI, and the obtaining module 702 is specifically configured to generate the APN according to one or more modified DNNs of parameters, such as S-NSSAI, a PDU session ID, an identifier of a control plane function network element, and a random number, in the PDU session establishment request. In particular, the benefit of using random numbers for modification is that the network sensitive information can be hidden, and in order to ensure the uniqueness of the random numbers, S-NSSAI, PDU session ID, SMF + PGW-C ID, and other uniqueness parameters such as time parameters can be used as the input of the random number generation function when generating the random numbers. After generating the random number, the user data managing network element may use the random number as a modification of the DNN. In TS23.003 with APN modification method, can refer to the APN modification method to modify DNN. By adopting the method, DNN in the PDU session requested to be established by the terminal can be mapped to the unique APN within the range of the terminal, so that when the terminal establishes different PDU sessions specifically having the same DNN, the parameters for modifying the DNN are different, and the generated APN is different. Thereby ensuring that different PDU sessions of the same DNN have different APNs when switched to a PDN connection in the 4G network.

Optionally, an embodiment of the present application provides a chip system, where the chip system includes a processor, and is used to support a terminal to implement the session establishment method. In one possible design, the system-on-chip further includes a memory. The memory is used for storing program instructions and data necessary for the terminal. The chip system may be formed by a chip, and may also include a chip and other discrete devices, which is not specifically limited in this embodiment of the present application.

Optionally, an embodiment of the present application provides a chip system, where the chip system includes a processor, and is configured to support a control plane function network element to implement the session establishment method. In one possible design, the system-on-chip further includes a memory. The memory is used for storing program instructions and data necessary for the control plane function network element. The chip system may be formed by a chip, and may also include a chip and other discrete devices, which is not specifically limited in this embodiment of the present application.

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

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

Although the present application has been described in conjunction with specific features and embodiments thereof, it will be evident that various modifications and combinations can be made thereto without departing from the spirit and scope of the application. Accordingly, the specification and figures are merely exemplary of the present application as defined in the appended claims and are intended to cover any and all modifications, variations, combinations, or equivalents within the scope of the present application. It will be apparent to those skilled in the art that various changes and modifications may be made in the present application without departing from the spirit and scope of the application. Thus, if such modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is intended to include such modifications and variations as well.

Claims

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

a terminal sends a first request message for establishing a Packet Data Unit (PDU) session, wherein the first request message comprises a Data Network Name (DNN);

the terminal receives a first response message, wherein the first response message comprises an access point name APN corresponding to the PDU session; wherein the APN is unique within the range of the terminal;

and the terminal sends a second request message for establishing a Packet Data Network (PDN) connection to a mobile management network element, wherein the second request message comprises the APN.

2. The method of claim 1, wherein the APN is carried in a protocol configuration item, PCO.

3. The method of claim 1, wherein the first request message further comprises a PDU session identifier of the PDU session, and wherein the first response message further comprises the PDU session identifier; before the sending of the second request message for establishing the PDN connection to the mobility management network element, the method further includes:

and saving the APN into a session context indicated by the PDU session identification.

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

and sending indication information, wherein the indication information is used for indicating that all PDU sessions established by the terminal or a specific PDU session needs to be switched to the 4G network subsequently.

5. A method according to any of claims 1-3, wherein said second request message is an attach request or a PDN connection establishment request.

6. A method for session establishment, the method comprising:

a control plane function network element receives a first request message for requesting to establish a Packet Data Unit (PDU) session from a terminal; wherein the first request message comprises a data network name DNN;

and acquiring an access point name APN corresponding to the PDU session, wherein the APN is unique within the range of the terminal.

7. The method of claim 6, further comprising:

and sending a first response message to the terminal, wherein the first response message comprises the APN.

8. The method of claim 7, wherein the APN is carried in a protocol configuration item, PCO.

9. The method according to any one of claims 6-8, further comprising:

and the control plane function network element sends the APN, the DNN and the information of the control plane function network element to a user data management network element.

10. Method according to any of claims 6-8, wherein said APN is determined by modifying said DNN by a parameter unique to a value within said terminal range.

11. The method according to any one of claims 6 to 8, wherein the first request message further includes a PDU session identifier and/or single network slice selection assistance information S-NSSAI of the PDU session, and the acquiring the access point name APN corresponding to the PDU session specifically includes:

and generating the APN according to the PDU session identifier and/or the S-NSSAI and the DNN.

12. The method according to any one of claims 6 to 8, wherein the first request message further includes a PDU session identifier and/or single network slice selection assistance information S-NSSAI of the PDU session, and the acquiring the access point name APN corresponding to the PDU session specifically includes:

the control plane function network element sends the PDU session identification and/or the S-NSSAI and the DNN to a user data management network element;

and the control plane function network element receives the APN from the user data management network element.

13. The method according to any of claims 7-8, wherein said method further comprises receiving a session update request from a mobility management network element, said session update request including said APN.

14. The method of claim 6, further comprising:

receiving a request for acquiring the session context of the terminal, which is sent by a mobility management network element;

sending a session context response to the mobility management network element, the session context response including the APN.

15. The method according to any one of claims 6-8, further comprising:

and acquiring subscription data of the APN.

16. The method of claim 15, wherein the obtaining subscription data for the APN comprises:

generating subscription data of the APN according to the subscription data of the DNN; the method further comprises the following steps:

and sending the subscription data of the APN to a user data management network element.

17. A terminal, characterized in that the terminal comprises: a transmitting module and a receiving module;

the sending module is configured to send a first request message for establishing a packet data unit PDU session, where the first request message includes a data network name DNN;

the receiving module is configured to receive a first response message, where the first response message includes an access point name APN corresponding to the PDU session; wherein the APN is unique within the range of the terminal;

the sending module is further configured to send a second request message for establishing a packet data network PDN connection to a mobility management network element, where the second request message includes the APN.

18. A terminal according to claim 17, characterised in that the APN is carried in a protocol configuration item, PCO.

19. The terminal of claim 17, wherein the first request message further includes a PDU session identifier of the PDU session, and wherein the first response message further includes the PDU session identifier; the terminal further comprises:

and the storage module is used for storing the APN into the session context indicated by the PDU session identification.

20. The terminal according to any of claims 17 to 19, wherein the sending module is further configured to send an indication message, where the indication message is used to indicate that all PDU sessions established by the terminal or a specific PDU session needs to be subsequently handed over to the 4G network.

21. A terminal according to any of claims 17-19, wherein said second request message is an attach request or a PDN connection establishment request.

22. A control plane function network element, comprising a receiving module and an obtaining module;

the receiving module is used for receiving a first request message for requesting to establish a Packet Data Unit (PDU) session from a terminal; wherein the first request message comprises a data network name DNN;

the acquisition module is configured to acquire an access point name APN corresponding to the PDU session, where the APN is unique within the terminal range.

23. The control plane functional network element of claim 22, wherein the network element further comprises: a sending module;

the sending module is configured to send a first response message to the terminal, where the first response message includes the APN.

24. The control plane functional network element of claim 23, wherein the APN is carried in a protocol configuration item, PCO.

25. The control-plane-capable network element of any of claims 23-24, wherein the sending module is further configured to send the APN, the DNN, and information of the control-plane-capable network element to a user data management network element.

26. A control plane functional network element as claimed in any of claims 22 to 24, wherein the APN is determined by modifying the DNN by a value-unique parameter within the terminal range.

27. The control plane functional network element of any of claims 22 to 24, wherein the first request message further includes a PDU session identifier of the PDU session and/or single network slice selection assistance information S-NSSAI, and the obtaining module is specifically configured to:

28. The control plane functional network element of any of claims 22 to 24, wherein the first request message further includes a PDU session identifier of the PDU session and/or single network slice selection assistance information S-NSSAI, and the obtaining module is specifically configured to:

sending the PDU session identifier and/or the S-NSSAI and the DNN to a user data management network element;

receiving the APN from the user data management network element.

29. The control-plane-capable network element of any of claims 23-24, wherein the receiving module is further configured to receive a session update request from a mobility management element, where the session update request includes the APN.

30. The control plane functional network element of claim 23, wherein the receiving module is further configured to receive a request sent by a mobility management element to obtain the session context of the terminal;

the sending module is further configured to send a session context response to the mobility management network element, where the session context response includes the APN and information of the control plane function network element.

31. Control plane functional network element according to any of claims 23-24,

the obtaining module is further configured to obtain subscription data of the APN.

32. The control plane functional network element of claim 31, wherein the obtaining module is specifically configured to generate subscription data of the APN according to the subscription data of the DNN;

the sending module is further configured to send the subscription data of the APN to a user data management network element.

33. An apparatus, comprising a processor and a memory;

the memory is configured to store computer-executable instructions that, when executed by the apparatus, cause the apparatus to perform a session establishment method according to any one of claims 1-5.

34. The apparatus of claim 33,

the device comprises a terminal or a chip in the terminal.

35. A control plane functional network element, comprising a processor and a memory;

the memory is configured to store computer-executable instructions that, when executed by the processor, cause the control plane function network element to perform the method for session establishment according to any one of claims 6 to 16.

36. A computer-readable storage medium having stored therein instructions which, when run on a computer, cause the computer to perform the session establishment method according to any one of claims 1-5.

37. A computer-readable storage medium having stored therein instructions which, when run on a computer, cause the computer to perform a session establishment method according to any one of claims 6-16.