WO2018201973A1 - Method and apparatus for message transmission - Google Patents

Abstract

The present application relates to the field of communication technology and discloses a method and apparatus for message transmission, for addressing a problem of load imbalance between devices serving a UE. The method of the present application comprises: a session management function device receives a delete instruction from a first device and indication information of a group to which the first device belongs; if the session management function device has received a first interface release message from the first device, second interface information in a UE session context is deleted according to the delete instruction; and when a downlink message is required to be sent, the session management function device sends to a second device the downlink message, wherein the second device is a device which is determined, according to the indication information of the group, as a device serving the UE. The present application is applied in the process of message transmission.

Description

Method and device for message transmission

This application claims the priority of a Chinese application filed on May 3, 2017, with the application number 201710305752.2, the invention titled "A Method and Apparatus for Message Transmission", and the application number submitted on April 3, 2018. The priority of the Chinese Patent Application No. 201101289567.3, entitled "A Method and Apparatus for Message Transmission", the entire contents of which is incorporated herein by reference.

Technical field

The present application relates to the field of communications technologies, and in particular, to a method and an apparatus for message transmission.

Background technique

In the 4th Generation Mobile Communication (4G), the Serving GateWay (SGW) can save the session context of the User Equipment (UE), and the session context of the UE includes the UE. The IP address of the Mobility Management Entity (MME), when the SGW needs to send a downlink message related to the UE to the MME, the IP of the MME serving the UE may be obtained from the saved session context of the UE. The address, and further, sends a downlink message related to the UE to the MME according to the obtained IP address.

If the session management function (SMF) of the 5th-Generation Mobile Communication (5G) is also adopted, the UE session context is saved in the SMF, and the UE session context is included in the The external interface information of the processing unit (or the AMF instance served by the UE) in the access and Mobility Management Function (AMF) of the UE service, when the SMF needs to send the downlink message related to the UE, The external interface information of the processing unit (or the AMF instance served by the UE) in the AMF that is served by the UE is obtained according to the session context of the UE, and the downlink message related to the UE is sent according to the obtained external interface information. The processing unit (or the AMF instance serving the UE) in the AMF that last served the UE.

However, in this method, each time the SMF needs to send a downlink message related to the UE, the SMF sends a downlink message to the processing unit (or the AMF instance served by the UE) in the AMF that was last served for the UE, which will cause the UE to Always being served by the same processing unit or AMF instance, load imbalance will occur.

Summary of the invention

The embodiment of the present invention provides a method and a device for transmitting a message, which can solve the problem that the session management function device sends a UE-related downlink message to the first device that is served by the UE for the last time, and the load is unbalanced.

To achieve the above objectives, the present application adopts the following technical solutions:

In a first aspect, the application provides a method for message transmission, the method comprising:

The session management function device receives the deletion indication from the first device and the indication information of the group to which the first device belongs. In the case that the session management function device receives the first interface release message from the first device, the session management function device is configured according to the session management function device. The deletion indicates that the second interface information in the UE session context is deleted. Then, when the session management function device needs to send the downlink message, the session management function device sends the downlink message to the second device, where the second device is the indication information according to the group. A determined device for serving the UE.

The deletion indication is used to indicate that the session management function device deletes the second interface information in the session context of the user equipment UE when the first interface release message is received, where the first interface is the radio access network RAN and the An interface between the first device, where the second interface is an interface between the first device and the session management function device.

The session management function device may be an AMF device, and the first device and the second device may each be an instance of the AMF group, or both the first device and the second device may be one of the AMF devices.

Compared with the prior art, when the first interface of the first device is released, the session management function device deletes the second interface information in the UE session context, and then when the session management function device needs to send the downlink message, Searching for the interface information of the first device serving the UE last time from the UE context, and then triggering the process of reselecting the second device serving the UE, the session management function device may send the downlink message to the second device. The phenomenon of load imbalance that always occurs when the same device is used to serve the UE is avoided.

In a possible design, the session management function device receives the deletion indication from the first device and the indication information of the group to which the first device belongs, and may be implemented as: the session management function device receives the session establishment request from the first device. The session establishment request includes the group indication information, the deletion indication, and the second interface information.

After the session management function device receives the session establishment request from the first device, the session management function device may save the indication information of the group, the deletion indication, and the second interface information in the UE session context.

The second interface information is saved in the UE session context, and before the UE is not switched to the idle state, the session management function device can directly communicate with the first device serving the UE according to the second interface information, without frequently reselecting The device served by the UE can improve the service quality when the UE is in the connected state. When the deletion indication is saved in the UE session context, the session management function device can delete the second interface information in the UE session context in time when receiving the release message of the first interface, so as to avoid the UE entering the connection state every time. A device service that solves the problem of load imbalance in the prior art.

In a possible design, the session management function device deletes the second interface information in the UE session context according to the deletion indication, which may be implemented by: the session management function device deleting the UE session context according to the deletion indication in the UE session context. Second interface information.

In a possible design, the session management function device receives the deletion indication from the first device and the indication information of the group to which the first device belongs, and may be implemented as: the session management function device receives the session establishment request from the first device. The session establishment request includes the indication information of the group and the second interface information, and then the session management function device receives the first interface release message from the first device, where the first interface release message includes a deletion indication.

After the session management function device receives the session establishment request from the first device, the session management function device may save the indication information of the group and the second interface information in the UE session context.

The second interface information is saved in the UE session context, and before the UE is not switched to the idle state, the session management function device can directly communicate with the first device serving the UE according to the second interface information, without frequently reselecting The device served by the UE can improve the service quality when the UE is in the connected state.

In a possible design, the session management function device receives the deletion indication from the first device and the indication information of the group to which the first device belongs, and may be implemented as: the session management function device receives the first interface from the first device. Release the message, the first interface releases the indication information including the group and the deletion indication in the message.

Before the session management function device receives the first interface release message from the first device, the session management function device receives a session establishment request from the first device, where the second interface information is included in the session establishment request, and then the session management function device The second interface information is saved in a UE session context.

The first interface release message carries the deletion indication, so that the session management function device deletes the second interface information in the UE session context in time when the first interface release message is received, so as to prevent the UE from entering the connection state every time. The same device service solves the problem of load imbalance in the prior art.

In a possible design, the session management function device deletes the second interface information in the UE session context according to the deletion indication, which may be implemented as follows: the session management function device deletes the session of the UE according to the deletion indication included in the first interface release message. Second interface information in context.

In one possible design, the indication information of the group is the group identity ID of the group; the session management function device may determine the second device serving the UE according to the group ID, and then the session management function device passes the session management function. The interface between the device and the second device sends a downlink message to the second device.

In a possible design, the indication information of the group is a default route of the group; when the session management function device needs to send a downlink message, the session management function device sends a downlink message to the device corresponding to the default route of the group. Then, the second device identifier of the device corresponding to the default route of the group is received, and the device corresponding to the default route of the group is the second device selected by the UE, and the session management function device uses the session management function device to The interface between the second device sends a downlink message to the second device corresponding to the second device identifier.

In a possible design, the indication information of the group is the default route of the group; when the session management function device needs to send the downlink message, the session management function device sends the device corresponding to the default route of the group to the second device. The device that sends the downlink message, where the second device is the default route of the group, is the second device selected by the UE.

In a possible design, after the session management function device sends a downlink message to the second device by using the device corresponding to the default route of the group, after the session management function device receives the message from the second device, the session The management function device saves the interface information between the session management function device and the second device in the UE session context.

By saving the interface information between the session management function device and the second device in the UE session context, the session management function device does not need to reselect each time the downlink message of the UE is sent before the UE switches to the idle state. The device serving the UE can save overhead and avoid the situation in which the UE service is interrupted due to reselection of the device served by the UE.

In a second aspect, the application provides a method for message transmission, the method comprising:

The session management function device acquires the stateless indication information and the group indication information of the group to which the first device belongs, and the stateless indication information is used to indicate that the session management function device determines the binding of the signaling connection corresponding to the user equipment UE to the first interface. When the downlink message needs to be sent after the release, the second device for serving the UE is selected according to the group indication information, and then, when the session management function device receives the release notification from the first device, when the session management function device needs When the downlink message is sent, the session management function device sends a downlink message to the second device. The first device is a device that serves the UE before the binding of the signaling connection and the first interface is released, the first interface is an interface between the radio access network RAN and the first device, and the second device is according to the group indication information. The determined device for serving the UE. The release notification is used to indicate that the binding of the signaling connection to the first interface has been released.

The session management function device may be an AMF device, and both the first device and the second device may be one instance of the AMF group, or both the first device and the second device may be one of the AMF devices. The group indication information of the group to which the first device belongs may be an AMF group ID, or may be a default route of the AMF group.

The binding release of the signaling connection and the first interface includes but is not limited to the following two situations:

The first type: the signaling connection corresponding to the UE is released, and the binding of the signaling connection to the first interface is also released.

The second type: the binding of the signaling connection to the first interface is released, and the signaling connection corresponding to the UE is not released.

Compared with the prior art, the session management function device may determine to re-select the service for the UE in the case that it is determined that the binding of the signaling connection corresponding to the UE and the first interface has been released, and the downlink message needs to be sent. The two devices send downlink messages, thus avoiding the load imbalance that always occurs when the same device provides services for the UE.

In a possible design, the session management function device may determine the binding release of the signaling connection corresponding to the UE and the first interface before the session management function device sends the downlink message to the second device.

In a possible design, if the session management function module needs to send a downlink message, and determines that the binding connection of the signaling connection corresponding to the UE and the first interface is released, determining, according to the group indication information, the second service for serving the UE device.

With the method, in the case that the session management function device determines that the binding between the signaling connection of the UE and the first interface is released, the second device that is determined to serve the UE can avoid the service provided by the first device to the terminal at all times. When the session management function device needs to send a downlink message, the second device may send a downlink message to the terminal.

In a possible design, the session management function device obtains the group indication information of the group to which the first device belongs, which may be implemented as follows:

The session management function device receives the session establishment request from the first device, where the session establishment request includes the group indication information; or the session management function device receives the release notification from the first device, where the release notification includes the group indication information.

In one possible design, the session management function device obtains stateless indication information, including:

The session management function device receives a session establishment request from the first device, where the session establishment request includes stateless indication information; or the session management function device receives the release notification notification from the first device, including stateless indication information; or, the session The management function device obtains stateless indication information from the local configuration information.

In another possible design, the release notification includes a deletion indication. The deletion indication is used to instruct the session management function device to delete the information of the first device.

With the method, the session management function device deletes the information about the first device in the UE session context when the binding of the signaling connection corresponding to the UE and the binding of the first interface is released, and then the session management function device needs to send When the downlink message is received, the information of the first device serving the UE last time cannot be searched from the UE context, and then the process of reselecting the second device serving the UE may be triggered, and the session management function device may send the downlink message. For the second device, the load imbalance that always occurs when the same device provides services for the UE is avoided.

In a possible design, after the session management function device receives the release notification from the first device, the session management function device deletes the information of the first device in the UE session context according to the stateless indication information.

In another possible design, after the session management function device receives the release notification from the first device, the session management function device saves the release state of the binding of the signaling connection with the first interface, and then when the session management function device When the downlink message needs to be sent, the session management function determines that the binding of the signaling connection to the first interface is released according to the release state of the binding of the signaling connection with the first interface, and then the session management function determines, according to the group indication information, that The second device served by the UE.

With the method, after the binding of the signaling connection to the first interface is released, the session management function device can save the release state of the binding of the signaling connection and the first interface, and further, if the session management function device needs to send the downlink message, Determining the second device for serving the UE, and avoiding that the first device is used to provide services for the UE, and the load is unbalanced. If the session management function does not need to send the downlink message, the second device for serving the UE does not need to be determined. Can save system overhead.

In another possible design, the group indication information is a group identity ID of the group to which the first device belongs; correspondingly, the session management function device sends a downlink message to the second device, which may be implemented as: The function device needs to send a downlink message, and determines that the binding of the signaling connection corresponding to the UE to the first interface is released, and then determines the second device that serves the UE according to the group ID.

In a third aspect, the present application provides an apparatus for message transmission, which may implement the functions performed by the session management function device in the above first aspect or the second aspect, and the functions may be implemented by hardware or by hardware. The corresponding software implementation. The hardware or software includes one or more modules corresponding to the above functions.

In one possible design, the apparatus includes a processor and a communication interface configured to support the apparatus to perform the corresponding functions of the above methods. The communication interface is used to support communication between the device and other network elements. The apparatus can also include a memory for coupling with the processor that retains the program instructions and data necessary for the apparatus.

In a fourth aspect, the application provides a system for message transmission, comprising the session management function device of the first aspect or the second aspect, the UE, the RAN, and a group to which the first device belongs.

In a fifth aspect, the present application provides a computer storage medium for storing computer software instructions for use in the above-described session management function device, including a program designed to perform the above aspects.

In a sixth aspect, the application provides a computer program product, such as a computer readable storage medium, comprising a program designed to perform the above aspects.

Compared with the prior art, when the first interface of the first device is released, the session management function device deletes the second interface information in the UE session context, and then when the session management function device needs to send the downlink message, Searching for the interface information of the first device serving the UE last time from the UE context, and then triggering the process of reselecting the second device serving the UE, the session management function device may send the downlink message to the second device. The phenomenon of load imbalance that always occurs when the same device is used to serve the UE is avoided.

DRAWINGS

1 is a schematic structural diagram of a communication system provided by the present application;

2 is a schematic structural diagram of another communication system provided by the present application;

3 is a schematic structural diagram of an AMF device provided by the present application;

4 is a schematic structural diagram of another AMF device provided by the present application;

FIG. 5 is a schematic structural diagram of an SMF device provided by the present application; FIG.

6 is a flowchart of a method for message transmission provided by the present application;

FIG. 7 is a flowchart of another method for message transmission provided by the present application;

FIG. 8 is a flowchart of another method for message transmission provided by the present application;

FIG. 9 is a schematic structural diagram of an apparatus for message transmission according to the present application;

FIG. 10 is a flowchart of another method for message transmission provided by the present application;

FIG. 11 is a schematic structural diagram of another apparatus for message transmission provided by the present application.

detailed description

The system architecture and the service scenario described in this application are for the purpose of more clearly explaining the technical solutions of the present application, and do not constitute a limitation on the technical solutions provided by the present application. Those skilled in the art may know that with the evolution of the system architecture and new services. The appearance of the scenario, the technical solution provided by the present application is equally applicable to similar technical problems.

It should be noted that, in the present application, the words "exemplary" or "such as" are used to mean an example, illustration, or illustration. Any embodiment or design described herein as "exemplary" or "for example" should not be construed as preferred or advantageous over other embodiments or designs. Rather, the use of the words "exemplary" or "such as" is intended to present the concepts in a particular manner.

It should be noted that in the present application, "(English: of)", the corresponding "(corresponding, relevant)" and "corresponding" may sometimes be mixed. It should be noted that When the difference is made, the meaning to be expressed is the same.

Before describing the technical solutions of the present application in detail, for the sake of easy understanding, the scenarios applied by the embodiments of the present application are first introduced.

The embodiment of the present application is applied to a communication system as shown in FIG. 1, which includes a session management function device 101, an access and mobility management function device 102, and an access network device 103.

The access and mobility management function device 102 includes multiple devices, for example, the first device and the second device, and the access and mobility management function device 102 may further include an ASF unit, and the ASF unit is a network. The function may be a default AMF instance as shown in FIG. 3, or may be a dedicated network function, for example, may be a load balancer.

The session management function device 101 is configured to receive the deletion indication from the first device and the indication information of the group to which the first device belongs, where the first device is the device currently serving the UE in the access and mobility management function device 102. The group to which the first device belongs is the access and mobility management function device 102.

The first device in the access and mobility management function device 102 is configured to send a first interface release message to the session management function device 101, where the first interface is an interface between the access network device 103 and the first device.

The session management function device 101 is further configured to delete, according to the deletion indication, the second interface information in the UE session context, where the first interface is the first device and the session management, in the case that the first interface release message from the first device is received. Interface between functional devices 101. Then, when the session management function device 101 needs to send a downlink message, the downlink device may be sent to the second device, where the second device is a device for serving the UE according to the indication information of the group.

It should be noted that the UE involved in the present application may include various handheld devices with wireless communication functions, in-vehicle devices, wearable devices, computing devices, or other processing devices connected to the wireless modem, and various forms of terminals. Mobile station (MS), user equipment (User Equipment, UE), terminal equipment (Terminal Equipment), soft terminal, and the like. For convenience of description, in the present application, the devices mentioned above are collectively referred to as UEs.

In addition, the present application is applicable to a 5G network. When the present application is applied to a 5G network, the architecture diagram of the communication system is as shown in FIG. 2, which includes an Authentication Server Function (AUSF) device and unified data management (Unified). Data Management (UDM) device, AMF device, SMF device, Policy Control Function (PCF) device, UE, Radio Access Network (RAN) or Access Network (AN), user User Plane Function (UPF) device, Data Network (DN) device.

The session management function device 101 in FIG. 1 can be implemented as the SMF device in FIG. 2, and the access and mobility management function device 102 in FIG. 1 can be implemented as the AMF device in FIG. 2, and the access network in FIG. Device 103 may be implemented as a RAN or AN in FIG. The following describes the session management function device 101 as the SMF device, the access and mobility management function device 102 as the AMF device, and the access network device 103 as the RAN.

The AMF device can serve the UE, authorize the access of the UE, and manage the mobility of the UE. At the same time, the AMF device is also used to transmit non-access stratum (NAS) messages between the UE and the SMF. The RAN can communicate with the UE and the AMF device. For example, after receiving the NAS message sent by the UE, the RAN can forward the NAS message to the AMF device. The SMF device can communicate with the AMF device, for example, can send downlink messages to the AMF device, and the like. The SMF device is also used to manage the session. For example, the SMF device can maintain interface information between the AMF device and the SMF device in the context of the UE session, so that the SMF device can directly obtain the downlink message for a certain UE. The interface information stored in the session context of the UE is determined to be the AMF device served by the UE.

The serial number marked on the connecting line between the devices in FIG. 2 is used to distinguish the interfaces between different devices. FIG. 2 is only an exemplary schematic diagram, and the serial number of the interface between the devices is not limited in this application. Exemplarily, in Figure 2, the UE communicates with the AMF through the N1 interface, the RAN communicates with the AMF through the N2 interface, communicates with the UPF through the N3 interface, and each UPF communicates through the N9 interface, and the UPF communicates with the DN through the N6 interface. . The SMF controls the SMF through the N4 interface. The AMF communicates with the SMF through the N11 interface. The AMF and the SMF obtain the user subscription data from the UDM through the N8 interface and the N10 interface respectively, and obtain the policy data from the PCF through the N15 interface and the N7 interface respectively. In addition, the AMF devices communicate through the N14 interface, and the AUSF communicates with the AMF through the N12 interface and communicates with the UDM through the N13 interface.

It should be noted that FIG. 1 and FIG. 2 are only schematic structural diagrams of a communication system to which the present application is applied. In actual deployment, the number of devices in the communication system is not limited to the number of devices shown in FIGS. 1 and 2. In addition, each device in FIG. 1 to FIG. 2 may be implemented by one physical device, or may be implemented by multiple physical devices, or may be a logical functional module in a physical device. limited.

It should be noted that the UE, the RAN, the AMF device, the SMF device, the AUSF device, and the UDM device in the above 5G network are only one name, and the name does not limit the device itself. In the 5G network and other networks in the future, the network element or the entity corresponding to the UE, the RAN, the AMF device, the SMF device, the AUSF device, and the UDM device may also be other names, which is not specifically limited in this embodiment of the present application. For example, the UDM device may be replaced with a Home Subscriber Server (HSS) or a User Subscription Database (USD) or a database entity, and the like, and is not described here.

It should be noted that the AMF device in FIG. 2 can be implemented in two ways. The first implementation manner is shown in FIG. 3. FIG. 3 shows one of the AMF devices, and the AMF device includes a database (Database, DB). At least one Load Balancer (LB) unit and at least two processing units. The LB unit is configured to select a processing unit for the UE, and distribute the received NAS message to a corresponding processing unit. The processing unit is configured to process the received NAS and other messages, and the multiple processing units can share the data in the database.

Specifically, each LB unit and the processing unit have an external interface. When the RAN device is initialized, the external interface of the LB unit in the AMF device is configured as an external interface of the AMF device in the RAN device, and when the RAN device receives the After the NAS message sent by the UE in the idle state, the RAN device first selects an AMF device, then selects one of the LB unit interfaces configured in the RAN device from the AMF device, and then sends the NAS message to the AMF device through the selected LB unit interface. After receiving the NAS message, the LB unit allocates a processing unit for the NAS message. When the UE is in the connected state, the RAN device can directly communicate with the processing unit, and there is no need to forward data through the LB unit.

The AMF device in FIG. 2 can also be implemented in a group manner. As shown in FIG. 4, the AMF group includes a database, at least one LB unit, and at least two AMF instances. The LB unit is configured to select an AMF instance for the UE, and distribute the received NAS message to the corresponding AMF instance. The AMF instance is used to process the received NAS and other messages, and the multiple AMF instances may share the data in the data.

Specifically, each LB unit and the AMF instance have an external interface. When the RAN device is initialized, the external interface of the LB unit is configured as an external interface of the AMF group in the RAN device, and when the RAN device receives the idle state. After the NAS message sent by the UE, the RAN device selects an AMF group, and then selects an LB unit interface of the AMF group, and sends the NAS message to the LB unit in the AMF group through the LB unit interface, and the LB unit receives After the NAS message, an AMF instance is assigned to the NAS message. When the UE is in the connected state, the RAN device can directly communicate with the AMF instance without having to forward data through the LB unit.

In the prior art, after the LB unit selects a processing unit or an AMF instance for the UE, the SMF device saves the external interface information of the processing unit or the AMF instance serving the UE when the session is established or the session is activated, in the UE session context. When the SMF device needs to send a downlink message, the SMF device always sends the downlink message to the processing unit served last time for the UE according to the last interface information of the processing unit or the AMF instance that is saved for the UE in the UE session context. AMF instance. This makes it impossible to trigger the reselection process for the processing unit or the AMF instance even if the UE switches from the idle state to the connected state, after saving the processing unit or the AMF instance serving as the UE in the UE session context of the SMF device, The UE will always be served by the same processing unit or the AMF instance. Even if the load of the AMF instance serving the UE last time is very large, and the load of other AMF instances in the AMF group is small, the AMF will still send the downlink message. The AMF instance that served the UE last time is prone to load imbalance.

In order to avoid the phenomenon of load imbalance, the principle of the present application is: when the AMF device in FIG. 2 is implemented as FIG. 3, the processing unit in the AMF device carries the deletion in the session establishment request or the N2 release message sent to the SMF device. Instructing and SMF identification, and in the case that the SMF device receives the N2 release message, the SMF device can delete the interface information between the processing unit and the SMF device in the UE session context according to the deletion indication, so that the SMF device needs to send the downlink message. When there is no interface information between the processing unit and the SMF device in the UE session context, the SMF device can only send the downlink message to the processing unit reselected according to the AMF identifier, thereby avoiding sending to the same processing unit each time. The problem of load imbalance caused by downstream messages.

Similarly, when the AMF in FIG. 2 is implemented as FIG. 4, the AMF instance in the AMF group carries the deletion indication and the AMF group identifier in the session establishment request or the N2 release message sent to the SMF device, and then received on the SMF device. In the case of the N2 release message, the SMF device can delete the interface information between the AMF instance and the SMF device in the UE session context according to the deletion indication, so that when the SMF device needs to send the downlink message, there is no AMF instance in the UE session context. Interface information with the SMF device, so the SMF device can only send downlink messages to the reselected AMF instance according to the AMF group identity, thus avoiding the load imbalance that occurs when sending downlink messages to the same AMF instance each time. problem.

In the embodiment of the present application, the structure of the SMF device in FIG. 1 and FIG. 2 is as shown in FIG. 5. The SMF device may include: a memory 501, a processor 502, a communication interface 503, and a bus 504. Connections between devices and mutual communication.

The communication interface 503 can be implemented by an antenna, and can be used for data interaction with an external network element. For example, the communication interface 503 of the SMF device can send and receive data packets or other information between the AMF device.

The processor 502, which may be a central processing unit (CPU), may be an application specific integrated circuit (ASIC), or one or more configured to implement the embodiments of the present invention. Integrated circuits. For example: one or more microprocessors (English: Digital Singnal Processor, DSP), or one or more Field Programmable Gate Arrays (FPGAs). The processor 502 has a processing management function. Specifically, the processor 502 in the SMF device can process data or information sent by the received AMF device, the UPF device, or the PCRF device, or process information or data sent by other devices. .

The memory 501 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 information storage instructions and instructions. Type of dynamic storage device, or Electrostatic Erasable Programmable Read-Only Memory (EEPROM), Compact Disc Read-Only Memory (CD-ROM) or other optical disc storage, optical disc Storage (including compact discs, laser discs, optical discs, digital versatile discs, Blu-ray discs, etc.), magnetic disk storage media or other magnetic storage devices, or can be used to carry or store desired program code in the form of instructions or data structures and can be Any other medium accessed by the computer, but is not limited to this. Memory 501 can exist independently and is coupled to processor 502 via bus 504. Memory 501 can also be integrated with processor 502.

The method for message transmission provided by the present application will be specifically described below in conjunction with the communication system shown in FIGS. 1 to 5 and the AMF device and the SMF device.

First, the terminology involved in this application is briefly introduced to facilitate understanding.

1), the first interface

The first interface is an interface between the AMF device and the RAN device shown in FIG. 2 (corresponding to N2 in FIG. 2).

2), the second interface

The second interface is an interface between the AMF device and the SMF device shown in FIG. 2, specifically an interface between the first device and the SMF device that is serving the UE in the AMF device.

3), the first device

When the AMF device in FIG. 2 is implemented as FIG. 3, the first device is a processing unit in the AMF device, the group to which the first device belongs is the AMF device where the processing unit is located, and the second interface is one of the AMF devices. The interface between the unit and the SMF device (corresponding to N11 in Figure 2).

When the AMF device in FIG. 2 is implemented as the AMF group shown in FIG. 4, the first device is an AMF instance in the AMF group, the group to which the first device belongs is the AMF group in which the AMF instance is located, and the second The interface is an interface between an AMF instance and an SMF device in the AMF group (corresponding to N11 in FIG. 2).

4), the second device

The second device is a device that is re-determined for serving the UE after the SMF device deletes the second interface information between the first device and the SMF device saved in the UE session context.

When the AMF device of Figure 2 is implemented as Figure 3, the second device is one of the AMF devices.

When the AMF device in FIG. 2 is implemented as the AMF group shown in FIG. 4, the second device is an AMF instance in the AMF group.

As shown in FIG. 6, in order to solve the problem of load imbalance in the prior art, an embodiment of the present application provides a method for message transmission. When the method is applied to the scenario shown in FIG. 4, the UE and the RAN are used. The interaction process between the device, the AMF instance 1, the AMF instance 2, and the SMF device is described as an example. The AMF instance 1 and the AMF instance 2 belong to the same AMF group. The method includes three phases, and the first phase is The session establishment process corresponds to steps 601 to 603; the second phase is a process in which the UE enters an idle state, corresponding to steps 604 to 607; and the third phase is a process in which the UE re-enters the connection state when the SMF device needs to send a downlink message. Corresponding to steps 608 to 611. The method specifically includes:

601. The UE sends a session establishment request to the AMF instance 1, and the AMF instance 1 receives the session establishment request.

The UE sends a session establishment request to the AMF instance 1 to trigger a user datagram protocol (PDU) session establishment process. When the UE initiates a PDU session establishment process, the UE is in a connected state, and the UE is in the connection state. Is the AMF instance 1.

602. The AMF instance 1 sends a session establishment request to the SMF device, and the SMF device receives the session establishment request.

The session establishment request may have the following three implementation manners.

The first type: the second interface information (N11 interface information) of the AMF instance 1 is included in the session establishment request.

The second type: the session establishment request includes the second interface information (N11 interface information) of the AMF instance 1, and the indication information of the AMF group to which the AMF instance 1 belongs.

The third type: the session establishment request includes the second interface information (N11 interface information) of the AMF instance 1, the deletion indication, and the indication information of the AMF group to which the AMF instance 1 belongs.

It should be noted that the indication information of the AMF group may be an AMF group ID or a default route of the AMF group. In the embodiment corresponding to FIG. 6 , the indication information of the AMF group is taken as an example of the AMF group ID.

It should be noted that, if the third implementation manner is adopted, the AMF instance 1 needs to first determine whether the AMF group to which it belongs supports statelessness. If the AMF group supports stateless, the AMF instance 1 will carry the deletion indication. In the session establishment request. With reference to FIG. 4, the AMF group supports the stateless state, the AMF instance does not save the UE session context information, and the session context information of the UE served by each AMF instance in the AMF group is saved in the DB of the AMF group. The AMF instances in the same AMF group can share the UE session context information stored in the DB, so that each AMF instance can process not only related information of the UEs served by itself but also related information of other UEs.

The deletion indication is used to instruct the SMF device to delete the second interface information in the UE session context stored by the SMF device when receiving the first interface release message.

603. The SMF device saves information carried in the session establishment request in a UE session context.

It can be understood that, in each implementation manner of the session establishment request described in the foregoing step 602, the session establishment request carries the second interface information of the AMF instance 1, because the AMF instance currently serving the UE is the AMF instance 1, so The SMF device needs to save the second interface information of the AMF instance 1 in the UE session context, so that when the UE is in the connected state, the SMF device can directly access the AMF serving the UE by using the second interface information saved in the UE session context. Example 1 sends a downlink message.

In addition, if the session establishment request further includes the indication information of the AMF group, the SMF device further needs to save the indication information of the AMF group in the UE session context, and similarly, if the session establishment request further includes the deletion indication, the SMF device The deletion indication also needs to be saved in the UE session context.

It should be noted that the UE session context can be saved in the SMF device or in other devices with storage functions.

The foregoing steps 601 to 603 are the session establishment process. After the session is established, when the UE enters the idle state, the process of the UE entering the idle state needs to be performed.

604. The RAN device sends a first interface release request message to the AMF instance 1, and the AMF instance 1 receives the first interface release request message.

605. The AMF instance 1 device releases the first interface according to the first interface release request message.

It can be understood that after the AMF instance 1 releases the first interface between the AMF instance 1 and the RAN, the UE switches from the connected state to the idle state.

606. The AMF instance 1 sends a first interface release message to the SMF device, and the SMF device receives the first interface release message.

It should be noted that, corresponding to step 602, the first interface release message also includes three implementation manners.

The first type: if the session establishment request is the first implementation manner described in step 602, the first interface release message may carry the deletion indication, the indication information of the AMF group to which the AMF instance 1 belongs, and the first interface release notification.

The second type: if the session establishment request is the second implementation manner described in the step 602, the first interface release message may carry the deletion indication and the first interface release notification.

The third type: if the session establishment request is the third implementation manner described in step 602, the first interface release message may carry the first interface release notification.

It should be noted that if AMF instance 1 is to carry the deletion indication in the first interface release message, it is necessary to first determine whether the AMF group to which it belongs supports stateless. If the AMF group supports stateless, AMF instance 1 will delete. The indication is carried in the first interface release message.

607. The SMF device deletes the second interface information in the UE session context according to the deletion indication, when the first interface release message is received.

If the first interface release message carries the deletion indication, the SMF device directly deletes the second interface information in the UE session context according to the deletion indication carried in the first interface release message. If the deletion indication is not carried in the first interface release message, and the deletion indication is saved in the UE session context, the SMF device deletes the second interface information according to the deletion indication saved in the UE session context.

The SMF device receives the first interface release message, indicating that the UE has entered the idle state, and the SMF device deletes the second interface information in the UE session context, so that the SMF device still avoids the UE session context when the UE re-enters the link state. The second interface information in the AMF instance 1 is taken as an AMF instance serving the UE. At this time, since the second interface information does not exist in the UE session context, the AMF instance serving as the UE can only be re-selected in the AMF group, and the UE is always served by the same AMF instance.

The foregoing steps 604 to 607 are the process of the UE entering the idle state. If the subsequent SMF device receives the downlink message for the UE, the following steps 608 to 611 are also performed to enable the UE to re-enter the connection state.

608. When the SMF device needs to send a downlink message, the SMF device selects an AMF instance serving as the UE from the AMF group according to the AMF group ID, for example, AMF instance 2.

The SMF device may look up an AMF instance serving the UE from a Network Function Repository Function (NRF) device or other device according to the AMF group ID. The specific method for the SMF device to select an AMF instance for serving the UE according to the AMF group ID is the same as that of the prior art, and details are not described herein again.

In a possible implementation, the SMF device may save the interface information between the SMF device and the AMF instance 2 in the UE session context after reselecting the AMF instance 2 serving the UE, so that the UE is always connected. In the case of a state, the SMF device communicates directly with AMF instance 2 without having to reselect the AMF instance. Alternatively, in another possible implementation manner, the SMF device may also save the interface information between the SMF device and the AMF instance 2 through the subsequent steps 610 to 611.

609. The SMF device sends a downlink message to the AMF instance 2 through the interface between the SMF device and the AMF instance 2. The AMF instance 2 receives the downlink message.

It should be noted that after the SMF device sends the downlink message to the AMF instance 2 that is found according to the AMF group identity, the AMF instance 2 may also re-select an AMF instance for the UE, for example, AMF instance 3, and send the message to the AMF instance 3. The downlink message, or the identifier of the AMF instance 3 is sent to the SMF device, and the SMF device sends a downlink message to the AMF instance 3.

The flow of the subsequent processing of the downlink message after the AMF instance 2 receives the downlink message is the same as that in the prior art, and details are not described herein again.

It should be noted that, in the subsequent process, after the UE re-enters the connection state, steps 610 to 611 may also be performed.

610. The AMF instance 2 sends a response message to the SMF device, where the response message includes interface information between the AMF instance 2 and the SMF device, and the SMF device receives the response message.

611. The SMF device saves interface information between the AMF instance 2 and the SMF device in a UE session context.

The method for transmitting a message provided by the embodiment of the present application is that the SMF device in the prior art always selects an AMF instance that is served by the UE to provide a service for the UE. In the embodiment of the present application, the RAN is released in the RAN. When the interface between the AMF instances served by the UE indicates that the UE enters the idle state, the SMF device deletes the interface information between the SMF device in the UE context and the AMF instance served by the UE, and then the SMF device needs to send the UE for the UE. When the downlink message is received, the interface information between the AMF instance serving the UE and the SMF device last time cannot be directly searched from the UE context, and the AMF instance served last time for the UE is not selected, but is re-selected. The AMF instance avoids the load imbalance caused by the SMF device always selecting the AMF instance that was last served for the UE.

In the embodiment shown in FIG. 6 , the indication information of the AMF group is taken as an example of the AMF group ID. In another implementation manner provided by the embodiment of the present application, the indication information of the AMF group is used. It can also be a default route of the AMF group. When the indication information of the AMF group is the default route of the AMF group, as shown in FIG. 7, the method can be implemented as the following steps 701 to 712.

The steps 701 to 707 are the same as the above steps 601 to 607, and the steps 711 to 712 are the same as the above steps 610 to 611, and details are not described herein again.

708. When the SMF device needs to send the downlink message, the SMF device sends a downlink message to the device corresponding to the default route of the AMF group, and the device corresponding to the default route of the AMF group receives the downlink message.

The default route of the AMF group is directed to the ASF unit, where the ASF unit is a network function, which may be a default AMF instance in the AMF group, or may be a dedicated network function, for example, may be a load. Equalizer.

709. The ASF unit selects an AMF instance serving the UE, for example, AMF instance 2.

710. The ASF unit sends a downlink message to the AMF instance 2, and the AMF instance 2 receives the downlink message.

Alternatively, in another possible implementation, step 710 may be replaced by the ASF unit sending an identifier of the AMF instance 2 to the SMF device, and then the SMF device sends a downlink message to the AMF instance 2 according to the identifier of the AMF instance 2.

The embodiment corresponding to FIG. 6 and FIG. 7 is an implementation manner when the method for message transmission of the present application is applied to the scenario shown in FIG. 4. In another embodiment of the present application, the method for message transmission of the present application may also be In the scenario shown in FIG. 3, the interaction process between the UE, the RAN device, the processing unit 1, the processing unit 2, and the SMF device is taken as an example. The processing unit 1 and the processing unit 2 belong to the same AMF. The device, as shown in Figure 8, includes:

801. The UE sends a session establishment request to the processing unit 1, and the processing unit 1 receives the session establishment request.

The UE sends the session establishment request to the processing unit 1 to trigger the process of establishing the PDU session. When the UE initiates the process of establishing the PDU session, the UE is in a connected state, and the UE is serving the processing unit 1 at this time.

802. The processing unit 1 sends a session establishment request to the SMF device, and the SMF device receives the session establishment request.

The session establishment request may have the following three implementation manners.

The first type: the session establishment request includes the second interface information (N11 interface information) of the processing unit 1.

The second type: the session establishment request includes the second interface information (N11 interface information) of the processing unit 1 and the indication information of the AMF device to which the processing unit 1 belongs.

The third type: the session establishment request includes the second interface information (N11 interface information) of the processing unit 1, the deletion indication, and the indication information of the AMF device to which the processing unit 1 belongs.

It should be noted that the indication information of the AMF device may be an AMF device ID or a default route of the AMF device. In the embodiment corresponding to FIG. 8 , the indication information of the AMF device is taken as an AMF device ID as an example for description.

803. The SMF device saves information carried in the session establishment request in a UE session context.

It can be understood that, in each implementation manner of the session establishment request described in the foregoing step 802, the second interface information of the processing unit 1 is carried in the session establishment request, because the processing unit currently serving the UE is the processing unit 1, so The SMF device needs to save the second interface information of the processing unit 1 in the UE session context, so that when the UE is in the connected state, the SMF device can directly process the service for the UE by using the second interface information saved in the UE session context. Unit 1 sends a downlink message.

In addition, if the session establishment request further includes the indication information of the AMF device, the SMF device further needs to save the indication information of the AMF device in the UE session context. Similarly, if the session establishment request further includes a deletion indication, the SMF device needs to The deletion indication is saved in the UE session context.

The foregoing steps 801 to 803 are the session establishment process. After the session is established, when the UE enters the idle state, the process of the UE entering the idle state needs to be performed.

804. The RAN device sends a first interface release message to the processing unit 1, and the processing unit 1 receives the first interface release message.

805. The processing unit 1 releases the first interface according to the first interface release message.

It can be understood that after the processing unit 1 releases the first interface between the processing unit 1 and the RAN, the UE is switched from the connected state to the idle state.

806. The processing unit 1 sends a first interface release message to the SMF device, and the SMF device receives the first interface release message.

It should be noted that, corresponding to step 802, the first interface release message also includes three implementation manners.

The first type: if the session establishment request is the first implementation manner described in step 802, the first interface release message may carry the deletion indication, the indication information of the AMF group to which the processing unit 1 belongs, and the first interface release notification.

The second type: if the session establishment request is the second implementation manner described in the step 802, the first interface release message may carry the deletion indication and the first interface release notification.

The third type: if the session establishment request is the third implementation manner described in step 802, the first interface release message may carry the first interface release notification.

It should be noted that, if the processing unit 1 needs to carry the deletion indication in the first interface release message, it is necessary to first determine whether each processing unit of the AMF device to which it belongs supports stateless. If each processing unit of the AMF device supports stateless processing, The unit 1 will carry the deletion indication in the first interface release message. In conjunction with FIG. 3, each processing unit of the AMF device supports stateless means that the UE session context information is not saved in each processing unit, and the UE served by each processing unit The session context information is saved in the DB, and the processing unit in the same AMF device can share the UE session context information stored in the DB.

807. The SMF device deletes the second interface information in the UE session context according to the deletion indication, when the first interface release message is received.

If the first interface release message carries the deletion indication, the SMF device directly deletes the second interface information in the UE session context according to the deletion indication carried in the first interface release message. If the deletion indication is not carried in the first interface release message, and the deletion indication is saved in the UE session context, the SMF device deletes the second interface information according to the deletion indication saved in the UE session context.

The SMF device receives the first interface release message, indicating that the UE has entered the idle state, and the SMF device deletes the second interface information in the UE session context, so that the SMF device still avoids the UE session context when the UE re-enters the link state. The second interface information in the processing unit 1 is treated as a processing unit serving the UE. At this time, since the second interface information does not exist in the UE session context, the processing unit serving as the UE can only be reselected in the SMF device, and the UE is always served by the same processing unit.

The foregoing steps 804 to 807 are the process of the UE entering the idle state. If the subsequent SMF device receives the downlink message for the UE, the following steps 808 to 811 are also performed to enable the UE to re-enter the connection state.

808. When the SMF device needs to send a downlink message, the SMF device selects an ASF unit of the AMF device according to the AMF device ID.

The SMF device can search for an external interface of the AMF device from the NRF device or other device according to the AMF device ID, and the interface can be the transport layer information of the ASF unit. In this embodiment, the ASF unit may be one LB unit in the AMF device, or may be one processing unit in the AMF device.

In the case that the ASF unit is a processing unit in the AMF device, the SMF device may directly send a downlink message to the processing unit, and the processing unit provides a service for the UE, or the processing unit receives the downlink message sent by the SMF device. Afterwards, the following steps 810 to 811 may also be performed to reselect the processing unit serving the UE and send the downlink message to the reselected processing unit.

809. The SMF device sends a downlink message to the ASF unit, and the ASF unit receives the downlink message.

It should be noted that when the ASF unit is an LB unit, steps 810 to 811 may also be performed.

810. The ASF unit selects a processing unit serving the UE, for example, the processing unit 2.

811. The ASF unit sends a downlink message to the processing unit 2, and the processing unit 2 receives the downlink message.

In another possible implementation manner, the ASF unit may further send an identifier of the processing unit 2 to the SMF device, and the SMF device sends a downlink message to the processing unit 2 according to the identifier of the processing unit 2.

The flow of the subsequent processing of the downlink message after the processing unit 2 receives the downlink message is the same as that in the prior art, and details are not described herein again.

It should be noted that, in the subsequent process, after the UE re-enters the connection state, steps 812 to 813 may also be performed.

812. The processing unit 2 sends a response message to the SMF device, where the response message includes interface information between the processing unit 2 and the SMF device, and the SMF device receives the response message.

813. The SMF device saves interface information between the processing unit 2 and the SMF device in a UE session context.

The method for message transmission provided by the embodiment of the present application, after the RAN releases the interface between the RAN and the processing unit serving the UE, the SMF device will between the SMF device in the UE context and the processing unit serving the UE. The interface is deleted, and when the SMF device needs to send a downlink message, the process of selecting the processing unit needs to be triggered again, and load balancing between the processing units can be implemented.

The solution provided by the embodiment of the present invention is mainly introduced from the perspective of the SMF device. It can be understood that the SMF device includes corresponding hardware structures and/or software modules for performing various functions. Those skilled in the art will readily appreciate that the present application can be implemented in a combination of hardware or hardware and computer software in combination with the elements and algorithm steps of the various examples described in the embodiments disclosed herein. Whether a function is implemented in hardware or computer software to drive hardware depends on the specific application and design constraints of the solution. A person skilled in the art can use different methods for implementing the described functions for each particular application, but such implementation should not be considered to be beyond the scope of the present invention.

The embodiment of the present application may divide the function module into the SMF device according to the foregoing method example. For example, each function module may be divided according to each function, or two or more functions may be integrated into one processing module. The above integrated modules can be implemented in the form of hardware or in the form of software functional modules. It should be noted that the division of modules in the embodiments of the present application is schematic, and is only a logical function division, and may be further divided in actual implementation.

In the case of dividing each functional module by using corresponding functions, the embodiment of the present application provides a device for message transmission, and the device can be implemented as the SMF device in the above embodiment. As shown in FIG. 9, FIG. 9 shows a possible structural diagram of the SMF device involved in the above embodiment. The SMF device includes: a receiving module 901, a deleting module 902, and a sending module 903.

The receiving module 901 is configured to receive the deletion indication from the first device and the indication information of the group to which the first device belongs, and the deletion indication is used to instruct the deletion module 902 to delete the user when the receiving module 901 receives the first interface release message. Second interface information in the device UE session context.

The deleting module 902 is configured to delete the second interface information in the UE session context according to the deletion indication if the receiving module 901 receives the first interface release message.

The sending module 903 is configured to send a downlink message to the second device when the downlink message needs to be sent.

In another possible implementation manner of the embodiment of the present application, the device further includes: a storage module 904.

The receiving module 901 is specifically configured to receive a session establishment request from the first device, where the session establishment request includes the group indication information, the deletion indication, and the second interface information.

The storage module 904 is configured to save the indication information of the group, the deletion indication, and the second interface information in a UE session context.

The deleting module 902 is specifically configured to: when the receiving module receives the first interface release message sent by the first device, delete the second interface information in the UE session context according to the deletion indication in the UE session context.

In another possible implementation manner of the embodiment of the present application, the receiving module 901 is specifically configured to receive a session establishment request from the first device, where the session establishment request includes the group indication information and the second interface information, and the receiving The first interface from the first device releases the message, and the first interface release message includes a deletion indication.

The storage module 904 is configured to save the indication information of the group and the second interface information in a UE session context.

In another possible implementation manner of the embodiment of the present application, the receiving module 901 is specifically configured to receive a session establishment request from the first device, where the session establishment request includes second interface information, and receive from the first device. The first interface releases the message, and the first interface release message includes the group indication information and the deletion indication.

The storage module 904 is configured to save the second interface information in a UE session context.

The deleting module 902 is specifically configured to delete the second interface information in the session context of the UE according to the deletion indication included in the first interface release message.

In another possible implementation manner of the embodiment of the present application, the indication information of the group is a group identity ID of the group;

Correspondingly, the sending module 903 is specifically configured to determine, according to the group ID, a second device that is served by the UE, and send, by using an interface between the device for transmitting the message and the second device, a downlink message to the second device.

In another possible implementation manner of the embodiment of the present application, the indication information of the group is a default route of the group;

The sending module 903 is specifically configured to send a downlink message to the device corresponding to the default route of the group, receive the second device identifier of the device corresponding to the default route of the group, and the second device is the default route corresponding to the group. The device is a second device selected by the UE. The second device corresponding to the second device identifier received by the receiving module sends a downlink message to the second device corresponding to the second device identifier.

In another possible implementation manner of the embodiment of the present application, the indication information of the group is a default route of the group;

The sending module 903 is configured to send, by the device corresponding to the default route of the group, a downlink message to the second device, where the device corresponding to the default route of the second device is the second device selected by the UE.

In addition, the storage module 904 is configured to save the interface information between the device for transmitting the message and the second device in the UE session context after the receiving module 901 receives the message from the second device.

Specifically, corresponding to the foregoing method embodiment, the receiving module 901 is configured to support the SMF device to receive the session establishment request sent in step 602 in FIG. 6, the first interface release message sent in step 606, the response message sent in step 610, and FIG. The first interface release message sent in step 702, the first interface release message sent in step 706, and the response message sent in step 711 is further used to support the SMF device to receive the session establishment request sent in step 802 in FIG. 8, and the step 806 sends the message. The first interface releases the message and the response message sent in step 812. The deleting module 903 is configured to support the SMF device to perform step 607 in FIG. 6, step 707 in FIG. 7, and step 807 in FIG. The sending module 903 is configured to support the SMF device to perform step 609 in FIG. 6, step 708 in FIG. 7, and step 809 in FIG. The storage module 904 is configured to support the SMF device to perform step 603 and step 611 in FIG. 6, step 703 and step 712 in FIG. 7, step 803 and step 813 in FIG.

All the related content of the steps involved in the foregoing method embodiments may be referred to the functional description of the corresponding functional modules, and details are not described herein again.

In the case of employing an integrated unit, it should be noted that the receiving module 901 and the transmitting module 903 shown in FIG. 9 can be integrated in the communication interface 503 shown in FIG. 5, so that the communication interface 503 executes the receiving module 901 and transmits. The specific function of module 903. The delete module 902 can be integrated into the processor 502 shown in FIG. 5, causing the processor 502 to perform the specific functions of the delete module 902. The storage module 904 can be integrated in the memory 501 shown in FIG. 5 to cause the memory 501 to perform the specific functions of the storage module 904.

As shown in FIG. 10, in order to solve the problem of load imbalance in the prior art, another embodiment of the present application provides a data transmission method. When the method is applied to the scenario in FIG. 4, the UE and the RAN device are used. The process of the interaction between the AMF instance and the SMF device is described as an example. The AMF instance 1 and the AMF instance 2 belong to the same AMF group. The method includes three phases. The first phase is a session establishment process, and the corresponding step is 1001. Go to step 1003; the second phase is a process in which the UE enters an idle state, corresponding to step 1004 to step 1007; the third phase is a process in which the UE re-enters the connection state when the SMF device needs to send a downlink message, corresponding to step 1008 to step 1009. The method specifically includes:

1001. The UE sends a session establishment request to the AMF instance 1, and the AMF instance 1 receives the session establishment request.

The UE sends the session establishment request to the AMF instance 1 to trigger the establishment of the PDU session. When the UE initiates the process of establishing the PDU session, the UE is in the connected state, and the UE is serving the AMF instance 1 at this time.

1002. The AMF instance 1 sends a session establishment request to the SMF device, and the AMF instance 1 receives the session establishment request.

The session establishment request may have the following three implementation manners.

The first type: the information of the AMF instance 1 is included in the session establishment request.

The information of the AMF instance 1 is used by the SMF device to address the AMF instance. For example, the information of the AMF instance 1 may be an AMF instance identifier, a uniform resource identifier (URI) of the service endpoint in the AMF instance, or an AMF instance. The resource identifier registered in the NRF device.

The second type: the session establishment request includes the information of the AMF instance 1 and the indication information of the AMF group to which the AMF instance 1 belongs.

The third type: the session establishment request includes the AMF instance 1 information, the stateless indication information, and the indication information of the AMF group to which the AMF instance 1 belongs.

It should be noted that the indication information of the AMF group may be an AMF group ID or a default route of the AMF group. In the embodiment corresponding to FIG. 9 , the indication information of the AMF group is taken as an example of the AMF group ID.

It should be noted that, if the third implementation manner is adopted, the AMF instance 1 needs to first determine whether the AMF group to which it belongs supports the stateless mode. If the AMF group supports the stateless mode, the AMF instance 1 will be stateless. The indication information is carried in the session establishment request. With reference to FIG. 4, the AMF group supports the stateless mode, that is, the AMF instance does not save the UE session context information when the UE is in the idle state, and the session context information of the idle state UE served by each AMF instance in the AMF group is The AMF instances in the same AMF group can share the UE session context information stored in the DB, so that each AMF instance can process not only related information of the UEs served by itself, but also can be processed. Information about other UEs.

The stateless indication information is used to indicate that the SMF device needs to send a downlink message to the AMF instance after the SMF device needs to send the downlink message to the AMF instance, and the SMF device needs to follow the indication information of the AMF group. The AMF instance is reselected from the AMF group and the downstream message is sent to the newly selected AMF instance.

The stateless indication information may be a single indication information, for example, carrying a bit in the message to indicate that the AMF group works in the stateless mode, or may be embodied in other manners, for example, carrying a special AMF in the message. The pointer indicates that the AMF group works in stateless mode (for example, if the AMF pointer identifier carried in the message is 1111, the AMF group works in the stateless mode).

The binding release of the signaling connection to the first interface includes but is not limited to the following two cases:

The first type: the signaling connection corresponding to the UE is released, and the binding of the signaling connection to the first interface is also released.

The second type: the binding of the signaling connection to the first interface is released, and the signaling connection corresponding to the UE is not released.

In a specific implementation, the signaling in the signaling connection may refer to a Next Generation Application Protocol (NGAP) signaling, or may be an N2 reference application protocol (N2AP).

It should be noted that, in addition to the foregoing method for acquiring the stateless indication information, the SMF may further obtain the foregoing stateless indication information from the local configuration information according to the indication information of the AMF group.

1003. The SMF device saves information carried in the session establishment request in a UE session context.

It can be understood that, in each implementation manner of the session establishment request described in the foregoing step 1002, the session establishment request carries the information of the AMF instance 1, because the AMF instance currently serving the UE is the AMF instance 1, so the SMF device needs The information of the AMF instance 1 is saved in the UE session context, so that when the UE is in the connected state, the SMF device can directly send the downlink message to the AMF instance 1 serving the UE by directly using the information of the AMF instance 1 saved in the UE session context. .

In addition, if the session establishment request further includes the indication information of the AMF group, the SMF device further needs to save the indication information of the AMF group in the UE session context. Optionally, if the session establishment request further includes the stateless indication information, the SMF device further needs to save the stateless indication information in the UE session context, or alternatively, the SMF device may save the stateless indication information in the AMF group. Group or AMF corresponding context.

It should be noted that the UE session context can be saved in the SMF device or in other devices with storage functions.

The above steps 1001 to 1003 are the session establishment process. After the session is established, when the UE enters the idle state, the process of the UE entering the idle state needs to be performed.

1004. The RAN device sends a release message to the AMF instance 1, and the AMF instance 1 receives the release message.

The release message is used to indicate that the AMF instance 1 releases the binding of the signaling connection corresponding to the UE to the first interface.

1005. The AMF instance 1 device releases the binding of the signaling connection corresponding to the UE to the first interface according to the release message.

It can be understood that after the AMF instance 1 releases the binding of the signaling connection corresponding to the UE between the AMF instance 1 and the RAN and the first interface, the UE switches from the connected state to the idle state.

1006. The AMF instance 1 sends a session update request or a release notification to the SMF device, where the session update request includes a release reason, and the SMF device receives the session update request or the release notification.

The reason for the release is used to indicate the reason for the release of the binding of the signaling connection corresponding to the UE to the first interface. The release notification is used to indicate that the binding of the signaling connection corresponding to the UE to the first interface has been released.

It should be noted that, corresponding to step 1002, the session update request message also includes three implementation manners.

The first type: If the session establishment request is the first implementation manner described in step 1002, the session update request may carry the indication information and the release reason of the AMF group to which the AMF instance 1 belongs. The optional session update request may also carry stateless indication information.

The second type: If the session establishment request is the second implementation manner described in step 1002, the session update request may carry the release reason. The optional session update request may also carry stateless indication information.

The third type: If the session establishment request is the third implementation manner described in step 1002, the session update request message may carry the release reason.

It should be noted that if the AMF instance 1 is to carry the stateless indication information in the session update request message, it is necessary to first determine whether the AMF group to which it belongs supports the stateless mode. If the AMF group supports the stateless mode, the AMF instance 1 The stateless indication information will be carried in the session update request.

Similarly, the release notification also includes the above three implementations.

It should be noted that, in this step, in addition to the AMF instance 1 sending a session update request or release notification to the SMF device, and in the session update request or carrying the release reason, the AMF instance 1 may also send a notification that the UE enters the idle state to the SMF device. Similarly, entering the idle state notification also includes the above three implementations.

1007. The SMF device determines, according to the release reason, the release notification, or the UE to enter the idle state notification, that the binding connection of the signaling connection corresponding to the UE and the first interface is released.

In one implementation, the SMF device deletes information of the AMF instance 1 in the UE session context according to the stateless indication information.

If the session update request message carries the stateless indication information, the SMF device directly deletes the information of the AMF instance 1 in the UE session context according to the stateless indication information carried in the session update request. If the state update indication message is not carried in the session update request message, and the stateless indication information is saved in the UE session context, the SMF device deletes the information of the AMF instance 1 according to the stateless indication information saved in the UE session context. In addition, the SMF device can obtain the stateless indication information from the local configuration information according to the information of the configured AMF group, and delete the information of the AMF strength 1 according to the stateless indication information in the local configuration information.

The SMF device determines that the UE has entered the idle state according to the received session update request or the release notification or according to the received UE entering the idle state notification. At this time, the SMF device deletes the information of the AMF instance 1 in the UE session context, and the UE can be avoided. Upon re-entering the connection state, the SMF device still uses AMF instance 1 as the AMF instance serving the UE according to the information of AMF instance 1 in the UE session context. At this time, since the AMF instance 1 information does not exist in the UE session context, the AMF instance serving as the UE can only be re-selected in the AMF group, and the same AMF instance is always used to serve the UE.

In another implementation manner, the SMF device does not delete the information of the AMF instance 1 in step 1007, and the SMF device determines that the UE has entered the idle state according to receiving the session update request or the release notification or according to the received UE entering the idle state notification. State, the SMF device sets the UE's Connection Management (CM) state to the idle state.

The above steps 1004 to 1007 are the process of the UE entering the idle state. If the subsequent SMF device receives the downlink message for the UE, the following steps 1008 to 1009 are also performed to enable the UE to re-enter the connection state.

1008. When the SMF device needs to send a downlink message, the SMF device selects an AMF instance serving as the UE from the AMF group according to the AMF group ID, for example, AMF instance 2.

Optionally, when the SMF device needs to send the downlink message, it may be determined whether the binding of the signaling connection corresponding to the UE and the first interface is released, and if it is determined that the binding of the signaling connection corresponding to the UE to the first interface is released, According to the AMF group ID, an AMF instance serving the UE is selected from the AMF group.

In an implementation manner, the SMF device queries the UE session context. If the information of the AMF instance is not saved in the UE session context, the SMF device selects an AMF instance serving the UE according to the AMF group ID.

In another implementation, the SMF device determines that the CM status of the UE is in an idle state, and the SMF device receives the stateless indication information from the AMF instance 1 (as in step 1001 or 1006) or the SMF device determines the AMF group according to the configuration. Working in the stateless mode, the SMF device selects an AMF instance serving the UE according to the AMF group ID even if the AMF instance information is saved in the UE session context.

The SMF device may look up an AMF instance serving the UE from a Network Function Repository Function (NRF) device or other device according to the AMF group ID. The specific method for the SMF device to select an AMF instance for serving the UE according to the AMF group ID is the same as that of the prior art, and details are not described herein again.

The SMF device may save the information of the AMF instance 2 in the UE session context after reselecting the AMF instance 2 serving the UE, so that the SMF device directly communicates with the AMF instance 2 when the UE is always in the connected state. There is no need to re-select the AMF instance.

1009. The SMF device sends a downlink message to the AMF instance 2, and the AMF instance 2 receives the downlink message.

It should be noted that after the SMF device sends the downlink message to the AMF instance 2 that is found according to the AMF group identity, the AMF instance 2 may also re-select an AMF instance for the UE, for example, AMF instance 3, and send the message to the AMF instance 3. The downlink message, or the identifier of the AMF instance 3 is sent to the SMF device, and the SMF device sends a downlink message to the AMF instance 3.

The flow of the subsequent processing of the downlink message after the AMF instance 2 receives the downlink message is the same as that in the prior art, and details are not described herein again.

The method for transmitting a message provided by the embodiment of the present application is that the SMF device in the prior art always selects an AMF instance that is served by the UE to provide a service for the UE. In the embodiment of the present application, the RAN is released in the RAN. When the interface between the AMF instances served by the UE is bound to the signaling corresponding to the UE, the UE enters an idle state, and the SMF device deletes the information of the AMF instance in the UE context, and then the SMF device needs to send the UE for the UE. When the downlink message is used, it is impossible to directly search for the information of the AMF instance that was last served for the UE from the UE context, and instead of continuing to select the AMF instance that was last served for the UE, the AMF instance is reselected, thus avoiding The SMF device always selects the load imbalance caused by the last AMF instance served for the UE.

In the case of dividing each functional module by using corresponding functions, the embodiment of the present application provides a device for message transmission, and the device can be implemented as the SMF device in the above embodiment. As shown in FIG. 11, FIG. 11 shows another possible structural diagram of the SMF device involved in the above embodiment. The SMF device includes an acquisition module 1101 and a transmission module 1102.

The obtaining module 1101 is configured to obtain the stateless indication information and the group indication information of the group to which the first device belongs, where the stateless indication information is used to indicate that after determining that the binding of the signaling connection corresponding to the user equipment UE and the first interface is released When the downlink message needs to be sent, the second device that is used for serving the UE is selected according to the group indication information, where the first device is a device that serves the UE before the binding of the signaling connection and the first interface is released, and the first interface is a wireless connection. The interface between the incoming network RAN and the first device.

The sending module 1102 is configured to: when the obtaining module 1101 receives the release notification from the first device, when the downlink message needs to be sent, send a downlink message to the second device, where the second device is determined according to the group indication information. A device that serves the UE. The release notification is used to indicate that the binding of the signaling connection corresponding to the UE to the first interface has been released.

In another possible implementation manner of the embodiment of the present application, the apparatus further includes a determining module 1103.

The determining module 1103 is configured to determine binding release of the signaling connection corresponding to the UE and the first interface.

In another possible implementation manner of the embodiment of the present application, the determining module 1103 is further configured to: if the sending module needs to send a downlink message, and the determining module 1103 determines that the signaling connection corresponding to the UE is released from the first interface, Then determining a second device for serving the UE according to the group indication information.

In another possible implementation manner of the embodiment of the present application, the acquiring module 1101 is specifically configured to receive a session establishment request from the first device, where the session establishment request includes the group indication information; or, the receiving is from the first A release notification of the device, and the group notification information is included in the release notification.

In another possible implementation manner of the embodiment of the present application, the acquiring module 1101 is configured to receive a session establishment request from the first device, where the session establishment request includes stateless indication information, or receive the information from the first device. The release notification includes the stateless indication information; or the stateless indication information is obtained from the local configuration information.

In another possible implementation manner of the embodiment of the present application, the apparatus further includes a deleting module 1104.

The deleting module 1104 is configured to delete the information of the first device in the UE session context according to the stateless indication information after the obtaining module 1101 receives the release notification from the first device.

In another possible implementation manner of the embodiment of the present application, the device further includes: a storage module 1105.

The storage module 1105 is configured to save the release state of the binding of the signaling connection and the first interface after the obtaining module 1101 receives the release notification from the first device.

Optionally, the determining module 1103 is further configured to determine that the binding of the signaling connection to the first interface is released according to the release state of the binding of the signaling connection with the first interface;

Further, the determining module 1103 is further configured to: if the sending module 1102 needs to send a downlink message, and the determining module 1103 determines that the binding of the signaling connection to the first interface is released according to the release state of the binding of the signaling connection with the first interface. And determining, according to the group indication information, a second device for serving the UE.

The group indication information is a group identity ID of the group to which the first device belongs;

The determining module 1103 is specifically configured to: if the sending module 1102 needs to send a downlink message, and the determining module 1103 determines that the binding of the signaling connection to the first interface is released according to the release state of the binding of the signaling connection and the first interface, The group ID is determined to be the second device served by the UE.

Specifically, corresponding to the foregoing method embodiment, the acquiring module 1101 is configured to support the SMF device to obtain the session establishment request sent by step 1002 in FIG. 10, and the first interface sent by the step 1006 releases the message. The sending module 1102 is configured to support the SMF device to perform step 1009 in FIG. The deleting module 1104 is configured to support the SMF device to perform step 1007 in FIG. The determining module 1103 is configured to support the SMF device to perform step 1008 in FIG. The storage module 1105 is configured to support the SMF device to perform step 1003 in FIG.

All the related content of the steps involved in the foregoing method embodiments may be referred to the functional description of the corresponding functional modules, and details are not described herein again.

In the case of employing an integrated unit, it should be noted that the obtaining module 1101 and the transmitting module 1102 shown in FIG. 11 may be integrated in the communication interface 503 shown in FIG. 5, so that the communication interface 503 executes the obtaining module 1101 and transmits. The specific function of module 1102. The determination module 1103 and the deletion module 1104 can be integrated into the processor 502 shown in FIG. 5, causing the processor 502 to perform the specific functions of the determination module 1103 and the deletion module 1104. The storage module 1105 can be integrated in the memory 501 shown in FIG. 5 to cause the memory 501 to perform the specific functions of the storage module 1105.

Embodiments of the present application also provide a computer storage medium for storing computer software instructions for use in the above-described SMF device, the device comprising a program designed to perform the steps performed by the SMF device in the above embodiment.

Embodiments of the present application also provide a computer program product, such as a computer readable storage medium, including a program designed to perform the steps performed by the SMF device in the above-described embodiments.

The steps of a method or algorithm described in connection with the present disclosure may be implemented in a hardware or may be implemented by a processor executing software instructions. The software instructions may be composed of corresponding software modules, which may be stored in a random access memory (RAM), a flash memory, a read only memory (ROM), an erasable programmable read only memory ( Erasable Programmable ROM (EPROM), electrically erasable programmable read only memory (EEPROM), registers, hard disk, removable hard disk, compact disk read only (CD-ROM) or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor to enable the processor to read information from, and write information to, the storage medium. Of course, the storage medium can also be an integral part of the processor. The processor and the storage medium can be located in an ASIC. Additionally, the ASIC can be located in a core network interface device. Of course, the processor and the storage medium may also exist as discrete components in the core network interface device.

In the several embodiments provided by the present application, it should be understood that the disclosed system, apparatus, and method may be implemented in other manners. For example, the device embodiments described above are merely illustrative. For example, the division of the unit is only a logical function division. In actual implementation, there may be another division manner, for example, multiple units or components may be combined or Can be integrated into another system, or some features can be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection through some interface, device or unit, and may be electrical or otherwise.

The units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, may be located in one place, or may be distributed to multiple network devices. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of the embodiment.

In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each functional unit may exist independently, or two or more units may be integrated into one unit. The above integrated unit can be implemented in the form of hardware or in the form of hardware plus software functional units.

Through the description of the above embodiments, those skilled in the art can clearly understand that the present application can be implemented by means of software plus necessary general hardware, and of course, by hardware, but in many cases, the former is a better implementation. . Based on such understanding, the technical solution of the present application, which is essential or contributes to the prior art, may be embodied in the form of a software product stored in a readable storage medium, such as a floppy disk of a computer. A hard disk or optical disk, etc., includes instructions for causing a computer device (which may be a personal computer, server, or network device, etc.) to perform the methods described in various embodiments of the present application.

The above is only the specific embodiment of the present application, but the scope of the present application is not limited thereto, and variations or alternatives within the technical scope of the present application should be covered by the scope of the present application. Therefore, the scope of protection of the present application should be determined by the scope of the claims.

Claims (32)

A method for message transmission, comprising: The session management function device receives the deletion indication from the first device and the indication information of the group to which the first device belongs, and the deletion indication is used to indicate that the session management function device deletes when receiving the first interface release message The second interface information in the user equipment UE session context, the first interface is an interface between the radio access network RAN and the first device, and the second interface is the first device and the session management function Interface between devices; And the session management function device deletes the second interface information in the UE session context according to the deletion indication, where the session management function device receives the first interface release message from the first device; When the session management function device needs to send a downlink message, the session management function device sends the downlink message to the second device, where the second device is determined according to the indication information of the group, The device served by the UE. The method according to claim 1, wherein the session management function device receives the deletion indication from the first device and the indication information of the group to which the first device belongs, including: The session management function device receives a session establishment request from the first device, where the session establishment request includes indication information of the group, the deletion indication, and the second interface information; After the session management function device receives the session establishment request from the first device, the method further includes: The session management function device saves the indication information of the group, the deletion indication, and the second interface information in the UE session context. The method according to claim 2, wherein the session management function device deletes the second interface information in the UE session context according to the deletion indication, including: The session management function device deletes the second interface information in the UE session context according to the deletion indication in the UE session context. The method according to claim 1, wherein the session management function device receives the deletion indication from the first device and the indication information of the group to which the first device belongs, including: The session management function device receives a session establishment request from the first device, where the session establishment request includes indication information of the group and the second interface information; The session management function device receives a first interface release message from the first device, where the first interface release message includes the deletion indication; After the session management function device receives the session establishment request from the first device, the method further includes: The session management function device saves the indication information of the group and the second interface information in the UE session context. The method according to claim 1, wherein the session management function device receives the deletion indication from the first device and the indication information of the group to which the first device belongs, including: The session management function device receives a first interface release message from the first device, where the first interface release message includes indication information of the group and the deletion indication; Before the session management function device receives the first interface release message from the first device, the method further includes: The session management function device receives a session establishment request from the first device, where the session establishment request includes the second interface information; The session management function device saves the second interface information in the UE session context. The method according to claim 4 or 5, wherein the session management function device deletes the second interface information in the UE session context according to the deletion indication, including: The session management function device deletes the second interface information in the session context of the UE according to the deletion indication included in the first interface release message. The method according to claim 1, wherein the indication information of the group is a group identity ID of the group; correspondingly, the session management function device sends the downlink message to a second device ,include: Determining, by the session management function device, a second device serving as the UE according to the group ID; The session management function device sends the downlink message to the second device by using an interface between the session management function device and the second device. The method according to claim 1, wherein the indication information of the group is a default route of the group; correspondingly, the session management function device sends the downlink message to a second device, including : When the session management function device needs to send a downlink message, the session management function device sends the downlink message to a device corresponding to the default route of the group; The session management function device receives the second device identifier of the device corresponding to the default route of the group, and the second device is the second device selected by the device corresponding to the default route of the group. device; The session management function device sends the downlink message to the second device corresponding to the second device identifier by using an interface between the session management function device and the second device. The method according to claim 1, wherein the indication information of the group is a default route of the group; correspondingly, the session management function device sends the downlink message to a second device, including : When the session management function device needs to send a downlink message, the session management function device sends the downlink message to the second device by using a device corresponding to the default route of the group, where the second device is The device corresponding to the default route of the group is the second device selected by the UE. The method according to any one of claims 7 to 9, wherein after the session management function device sends the downlink message to the second device by using a device corresponding to the default route of the group The method further includes: After the session management function device receives the message from the second device, the session management function device saves interface information between the session management function device and the second device in the UE session context. in. A device for message transmission, comprising: a receiving module, configured to receive a deletion indication from the first device, and indication information of the group to which the first device belongs, where the deletion indication is used to indicate that the deleting module receives the first interface release message when the receiving module receives Deleting the second interface information in the user equipment UE session context, where the first interface is an interface between the radio access network RAN and the first device, and the second interface is the first device and the message transmission Interface between devices; The deleting module is configured to: when the receiving module receives the first interface release message from the first device, delete the second interface information in the UE session context according to the deletion indication; And a sending module, configured to send the downlink message to the second device when the downlink message needs to be sent, where the second device is a device that is used to serve the UE according to the indication information of the group. The device according to claim 11, wherein the device further comprises: a storage module; The receiving module is configured to receive a session establishment request from the first device, where the session establishment request includes indication information of the group, the deletion indication, and the second interface information; The storage module is configured to save the indication information of the group, the deletion indication, and the second interface information in the UE session context. The device according to claim 12, characterized in that The deleting module is specifically configured to: when the receiving module receives the first interface release message sent by the first device, delete the UE session context according to the deletion indication in the UE session context The second interface information. The device according to claim 11, wherein the device further comprises: a storage module; The receiving module is configured to receive a session establishment request from the first device, where the session establishment request includes indication information of the group and the second interface information, and receiving from the first device The first interface releases the message, and the first interface release message includes the deletion indication; The storage module is configured to save the indication information of the group and the second interface information in the UE session context. The device according to claim 11, wherein the device further comprises: a storage module; The receiving module is configured to receive a first interface release message from the first device, where the first interface release message includes indication information of the group and the deletion indication; and receiving from the first a session establishment request of a device, where the session establishment request includes the second interface information; The storage module is configured to save the second interface information in the UE session context. Device according to claim 14 or 15, characterized in that The deleting module is configured to delete the second interface information in the session context of the UE according to the deletion indication included in the first interface release message. The device according to claim 11, wherein the indication information of the group is a group identity ID of the group; The sending module is specifically configured to determine, according to the group ID, a second device that serves the UE, and send, by using an interface between the device that transmits the message and the second device, to the second device. Describe the downlink message. The apparatus according to claim 11, wherein the indication information of the group is a default route of the group; The sending module is configured to send the downlink message to a device corresponding to the default route of the group, and receive a second device identifier of the device corresponding to the default route of the group, where the second device The device corresponding to the default route of the group is the second device selected by the UE; the second device received by the receiving module by the interface between the device for transmitting the message and the second device The second device corresponding to the device identifier sends the downlink message. The apparatus according to claim 11, wherein the indication information of the group is a default route of the group; The sending module is configured to send the downlink message to the second device by using a device corresponding to the default route of the group, where the device corresponding to the default route of the group is The second device selected by the UE. The device according to any one of claims 17 to 19, further comprising: a storage module; The storage module is configured to save interface information between the device for transmitting the message and the second device in the context of the UE session, after the receiving module receives the message from the second device . A method for message transmission, comprising: The session management function device acquires the stateless indication information and the group indication information of the group to which the first device belongs, and the stateless indication information is used to indicate that the session management function device determines the signaling connection corresponding to the user equipment UE and the first After the binding of the interface is released, the second device that serves the UE is selected according to the group indication information, where the first device is the signaling connection and the first interface. The device that serves the UE before the binding is released, where the first interface is an interface between the radio access network RAN and the first device; When the session management function device receives the release notification from the first device, when the session management function device needs to send a downlink message, the session management function device sends the downlink message to the second device. The second device is a device that is determined to serve the UE according to the group indication information. The method of claim 21, wherein the method further comprises: The session management function device determines that the binding of the signaling connection corresponding to the UE and the first interface is released. The method according to claim 21 or 22, wherein the session management function device acquires group indication information of a group to which the first device belongs, including: The session management function device receives a session establishment request from the first device, where the session establishment request includes the group indication information; or The session management function device receives the release notification from the first device, and the release notification includes the group indication information. The method according to claim 21 or 22, wherein the session management function device acquires the stateless indication information, including: The session management function device receives a session establishment request from the first device, where the session establishment request includes the stateless indication information; or The session management function device receives the release notification from the first device, where the release notification includes the stateless indication information; or The session management function device acquires the stateless indication information from the local configuration information. The method according to claim 21 or 22, wherein the group indication information is a group identity ID of the group to which the first device belongs; correspondingly, the method further includes: If the session management function device needs to send a downlink message, and the session management function device determines that the binding connection between the signaling connection corresponding to the UE and the first interface is released, the session management function device determines, according to the group ID, The second device served by the UE. An apparatus for message transmission, comprising: an obtaining module and a sending module; The acquiring module is configured to acquire the stateless indication information and the group indication information of the group to which the first device belongs, where the stateless indication information is used to indicate that the signaling connection corresponding to the user equipment UE is tied to the first interface. When the downlink message needs to be sent after the release, the second device for serving the UE is selected according to the group indication information, where the first device releases the binding of the signaling connection with the first interface. The device that serves the UE before, the first interface is an interface between the radio access network RAN and the first device; The sending module is configured to: when the obtaining module receives the release notification from the first device, when the downlink message needs to be sent, send the downlink message to the second device, where the second device is A device for serving the UE determined according to the group indication information. The device according to claim 26, wherein the device further comprises: a determining module; The determining module is configured to determine binding release of the signaling connection corresponding to the UE and the first interface. Device according to claim 26 or 27, characterized in that The acquiring module is specifically configured to receive a session establishment request from the first device, where the session establishment request includes the group indication information, or receive the release notification from the first device, The group indication information is included in the release notification. Device according to claim 26 or 27, characterized in that The acquiring module is specifically configured to receive a session establishment request from the first device, where the session establishment request includes the stateless indication information; or receive the release notification from the first device, where The stateless indication information is included in the release notification; or the stateless indication information is obtained from the local configuration information. The device according to claim 26 or 27, wherein the group indication information is a group identity ID of a group to which the first device belongs; The determining module is specifically configured to: if the sending module needs to send a downlink message, and the determining module determines that the binding of the signaling connection corresponding to the UE and the first interface is released, determining, according to the group ID, The second device of the UE service. A session management function device comprising a processor for coupling with a memory and reading instructions in the memory and performing the method of any of claims 1-10 in accordance with the instructions. A session management function device comprising a processor for coupling with a memory and reading instructions in the memory and performing the method of any one of claims 21-25 in accordance with the instructions.

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