A communication method, device and system

Abstract

A communication method, device, and system for implementing the handover of a session management network element. In this application, after the mobility management network element obtains the information of the target intermediate session management network element, it sends the information of the source session management network element to the target session management network element; after the target session management network element obtains the information of the source session management network element, it sends a first message to the source session management network element according to the information of the source session management network element; after the source session management network element receives the first message from the target intermediate session management network element, based on the first message, it notifies the source intermediate user plane network element to create a forwarding tunnel; through the method of this application, a forwarding tunnel from the source intermediate user plane network element to the target intermediate user plane network element is created, enabling the source intermediate user plane network element to forward data to the target intermediate user plane network element through the forwarding tunnel, implementing the handover from the target intermediate session management network element to the source session management network element, capable of maintaining the session and ensuring the service continuity of the terminal device.

Description

[0001] This application claims the priority of a Chinese patent application with the application number 201810278045.3 and the invention title "A Communication Method, Device and System", which was filed with the China National Intellectual Property Administration on March 30, 2018. The entire content of the Chinese patent application is incorporated herein by reference. Technical Field

[0002] This application relates to the field of communication technologies, and particularly to a communication method, device and system. Background Art

[0003] In a traditional communication system, it includes two parts: an access network and a core network. The access network is the edge part of a mobile communication system and is responsible for connecting terminal devices to the core network. The core network is responsible for connecting the terminal devices to different data networks (DNs) and implementing functions such as charging and mobility management. In the access network, its access function is mainly realized through base stations. The core network mainly includes the following core network devices: a mobility management network element, a session management network element, a user plane network element, etc.

[0004] When a terminal device requests to access a data network, the core network will create a session for the terminal device. In this way, the terminal device can perform data transmission with the data network based on the session to implement communication services. Among them, the core network includes the following processes when creating a session:

[0005] First, the terminal device sends a request message for requesting to establish a session or a service to the base station, and the base station sends the request message sent by the terminal device to the mobility management network element; the mobility management network element determines the session management network element according to the request message and sends a session request to the session management network element; after receiving the session request, the session management network element selects a user plane network element within its service area and initiates a session establishment process to the user plane network element, and finally establishes a complete session.

[0006] In some scenarios, a session of a terminal device may include multiple user plane network elements, such as an intermediate user plane network element connected to the base station and an anchor user plane network element connected to the DN. If the intermediate user plane network element and the anchor user plane network element are located in different service areas, the session management network elements in the corresponding service areas need to manage the intermediate user plane network element and the anchor user plane network element respectively. That is to say, there is an intermediate session management network element in service area 1 where the intermediate user plane network element is located to manage the intermediate user plane network element, and there is an anchor session management network element in service area 2 where the anchor user plane network element is located to manage the anchor user plane network element.

[0007] Due to the mobility of the terminal device, the terminal device may move from service area 1 to service area 3. At this time, the core network needs to select a new intermediate user plane network element within service area 3 to re - create the session of the terminal device to ensure the service continuity of the terminal device. Therefore, the intermediate session management network element in service area 3 in the core network is required to manage the new intermediate user plane network element.

[0008] However, there is currently no technical solution to implement the handover of the session management network element. Therefore, the core network cannot determine the intermediate session management network element that manages the new intermediate user plane network element in service area 3, which further leads to the inability to re - establish the session. Summary of the Invention

[0009] This application provides a communication method, device, and system to implement the handover of the session management network element.

[0010] In a first aspect, an embodiment of this application provides a communication method, which can be executed by a session management network element or a chip within the session management network element. The session management network element can be an SMF entity in 5G communication and can be other entities with session management functions in future communications. The method includes: First, the target intermediate session management network element obtains information of the source session management network element, and then, according to the information of the source session management network element, sends a first message to the source session management network element, where the source session management network element is the session management network element that controls the user plane network element interfacing with the source base station; the first message is used to establish a forwarding tunnel from the source intermediate user plane network element to the target intermediate user plane network element. The source intermediate user plane network element is the user plane network element controlled by the source session management network element and interfacing with the source base station, and the target intermediate user plane network element is the user plane network element controlled by the target intermediate session management network element and interfacing with the target base station.

[0011] Through the above method, by creating a forwarding tunnel from the source intermediate user plane network element to the target intermediate user plane network element, the source intermediate user plane network element can forward data to the target intermediate user plane network element through the forwarding tunnel, realizing the handover of the target intermediate session management network element to the source session management network element, and being able to maintain the session of the terminal device and ensure the service continuity of the terminal device.

[0012] In a possible design, before the target intermediate session management network element sends the first message to the source session management network element according to the information of the source session management network element, the target intermediate session management network element can first obtain first indication information, and the first indication information is used to indicate the target intermediate session management network element to create the forwarding tunnel.

[0013] Through the above method, the target intermediate session management network element can determine that a forwarding tunnel needs to be created currently by obtaining the first indication information, and then create the forwarding tunnel, which can improve the flexibility and efficiency of creating the forwarding tunnel.

[0014] In a possible design, there are multiple ways for the target intermediate session management network element to obtain the first indication information. Two of them are listed as follows:

[0015] First, the target intermediate session management network element can obtain the first indication information from the source session management network element; at this time, the target intermediate session management network element can directly interact with the source session management network element to obtain the first indication information.

[0016] Second, the target intermediate session management network element can obtain the first indication information from the mobility management network element.

[0017] Through the above method, the first indication information can be sent to the target intermediate session management network element by different network elements, providing different ways to create a forwarding tunnel, which can be applied to different scenarios and ensure a wider range of application scenarios.

[0018] In a possible design, after obtaining the first indication information, the target intermediate session management network element can, according to the first indication information, instruct the target intermediate user plane network element to create the forwarding tunnel.

[0019] Through the above method, using the first indication information group as the indication for creating the forwarding tunnel can ensure the success window of the forwarding tunnel and improve the creation efficiency of the forwarding tunnel.

[0020] In a possible design, the first message may include information for identifying the forwarding tunnel. Specifically, the first message includes the forwarding tunnel information corresponding to the target intermediate user plane network element.

[0021] Through the above method, the forwarding tunnel information corresponding to the target intermediate user plane network element included in the first message can enable the target intermediate session management network element to create the forwarding tunnel more conveniently and quickly.

[0022] In a possible design, in order to enable the target intermediate session management network element to directly interact with the source session management network element, the target intermediate session management network element needs to obtain the information of the source session management network element. Specifically, the target intermediate session management network element obtains the information of the source session management network element from the mobility management network element.

[0023] Through the above method, the target intermediate session management network element obtains the source session management network element, enabling direct interaction between the target intermediate session management network element and the source session management network element. The direct interaction mode between the target intermediate session management network element and the source session management network element is relatively fast and efficient, which can improve the efficiency of creating a forwarding tunnel.

[0024] In a possible design, after creating the forwarding tunnel, the target intermediate session management network element sets a forwarding tunnel release timer; when the forwarding tunnel release timer expires, the target intermediate session management network element notifies the intermediate user plane network element to release the forwarding tunnel.

[0025] Through the above method, by setting the forwarding tunnel release timer, tunnel resources can be saved. When releasing the forwarding tunnel, it only needs to determine whether the forwarding tunnel release timer has expired, without the need for the target intermediate session management network element to send other signaling, which can effectively save signaling resources.

[0026] In a possible design, in addition to creating a forwarding tunnel, a tunnel between the target intermediate user plane network element and the anchor user plane network element can also be created. The specific process is as follows:

[0027] The target intermediate session management network element obtains session information from the source session management network element according to the information of the source session management network element; or the target intermediate session management network element receives the session information from the mobility management network element;

[0028] Based on the session information, the target intermediate session management network element creates a tunnel between the target intermediate user plane network element and the anchor user plane network element;

[0029] Wherein, the session information includes at least one of the following: the uplink tunnel information of the anchor user plane network element, the information of the anchor session management network element; the anchor session management network element is the session management network element that controls the session between the anchor user plane network elements.

[0030] Through the above method, the data that needs to be transmitted between the data network and the terminal device can be transmitted through the tunnel between the target intermediate user plane network element and the anchor user plane network element, which can ensure that the terminal device can receive and send data in a timely manner and ensure the service continuity of the terminal device.

[0031] In a possible design, the first indication information can be carried in the session information.

[0032] Through the above method, the session information and the first indication information can be sent together, which can effectively save signaling resources and improve efficiency.

[0033] In a possible design, the information of the source session management network element may be carried in the session information.

[0034] Through the above method, the session information and the information of the source session management network element can be sent together, which can effectively save signaling resources and improve efficiency.

[0035] In a second aspect, an embodiment of the present application provides a communication method, which can be executed by a session management network element or a chip in the session management network element. The session management network element may be an SMF entity in 5G communication and may be other entities with session management functions in future communications. The method includes: First, the source session management network element receives a first message from the target intermediate session management network element, and then, based on the first message, the source session management network element notifies the source intermediate user plane network element to create the forwarding tunnel.

[0036] The first message is used to establish a forwarding tunnel from the source intermediate user plane network element to the target intermediate user plane network element. The source intermediate user plane network element is a user plane network element controlled by the source session management network element and interfacing with the source base station. The target intermediate session management network element is a session management network element that controls the target intermediate user plane network element interfacing with the target base station.

[0037] Through the above method, by creating a forwarding tunnel from the source intermediate user plane network element to the target intermediate user plane network element, the source intermediate user plane network element can forward data to the target intermediate user plane network element through the forwarding tunnel, realizing the handover from the target intermediate session management network element to the source session management network element, and being able to maintain the session and ensure the service continuity of the terminal device.

[0038] In a possible design, before the source session management network element receives the first message from the target intermediate session management network element, the source session management network element may first determine that it is necessary to establish the forwarding tunnel; and then send the first indication information to the target intermediate session management network element or the mobility management network element. The first indication information is used to instruct the target intermediate session management network element to create the forwarding tunnel.

[0039] Through the above method, when the source intermediate session management network element determines that it is necessary to create the forwarding tunnel, it sends the first indication information, thereby notifying the target intermediate session management network element to create the forwarding tunnel, which can improve the flexibility and efficiency of creating the forwarding tunnel.

[0040] In a possible design, there are various ways for the source session management network element to determine that it is necessary to establish the forwarding tunnel. When there is downlink data to be sent to the terminal device in the source session management network element or the source intermediate user plane network element, the source session management network element may determine that it is necessary to establish the forwarding tunnel.

[0041] By the above method, when there is downlink data to be sent to the terminal device, a forwarding tunnel is created; the source session management network element or the source intermediate user plane network element can send the downlink data to the terminal device through the forwarding tunnel, ensuring that the terminal device can receive the data in a timely manner.

[0042] In a possible design, the first message may include information for identifying the forwarding tunnel. Specifically, the first message includes the forwarding tunnel information corresponding to the target intermediate user plane network element.

[0043] By the above method, the forwarding tunnel information corresponding to the target intermediate user plane network element included in the first message can enable the target intermediate session management network element to create the forwarding tunnel more conveniently and quickly.

[0044] In a possible design, after creating the forwarding tunnel, the source session management network element can set a forwarding tunnel release timer; when the forwarding tunnel release timer expires, the source session management network element notifies the source intermediate user plane network element to release the forwarding tunnel.

[0045] By the above method, by setting the forwarding tunnel release timer, tunnel resources can be saved. When releasing the forwarding tunnel, it is only necessary to determine whether the forwarding tunnel release timer has expired, and there is no need for the source intermediate session management network element to send other signaling, which can effectively save signaling resources.

[0046] In a possible design, in addition to creating the forwarding tunnel, a tunnel between the target intermediate user plane network element and the anchor user plane network element can also be created. The specific process is as follows:

[0047] The source session management network element sends session information to the target intermediate session management network element to enable the target intermediate session management network element to create a tunnel between the target intermediate user plane network element and the anchor user plane network element; or

[0048] The source session management network element sends session information to the mobility management network element to enable the mobility management network element to send the session information to the target intermediate session management network element.

[0049] Wherein, the session information includes at least one of the following: the uplink tunnel information of the anchor user plane network element, the information of the anchor session management network element; the anchor session management network element is the session management network element that controls the anchor user plane network element.

[0050] By the above method, the data that needs to be transmitted between the data network and the terminal device can be transmitted through the tunnel between the target intermediate user plane network element and the anchor user plane network element, which can ensure that the terminal device can send and receive data in a timely manner and ensure the service continuity of the terminal device.

[0051] In a possible design, the first indication information may be carried in the session information.

[0052] Through the above method, the session information and the first indication information can be sent together, which can effectively save signaling resources and improve efficiency.

[0053] In a possible design, the information of the source session management network element may be carried in the session information.

[0054] Through the above method, the session information and the information of the source session management network element can be sent together, which can effectively save signaling resources and improve efficiency.

[0055] In a third aspect, an embodiment of the present application provides a communication method, which can be executed by a mobility management entity or a chip in the mobility management entity. The mobility management entity may be an AMF entity in 5G communication and may be other entities with session management functions in future communication. The method includes: the mobility management network element obtains information of a target intermediate session management network element; the mobility management network element sends the information of the source session management network element to the target intermediate session management network element according to the information of the target intermediate session management network element, where the source session management network element is a session management network element that controls the user plane network element interfacing with the source base station, and the target intermediate session management network element is a session management network element that controls the target intermediate user plane network element interfacing with the target base station.

[0056] Through the above method, the target intermediate session management network element obtains the information of the source session management network element, enabling the target intermediate session management network element to directly interact with the source session management network element.

[0057] In a possible design, the mobility management network element sends first indication information to the target intermediate session management network element, where the first indication information is used to instruct the target intermediate session management network element to create a forwarding tunnel from the source intermediate user plane network element to the target intermediate user plane network element, and the source intermediate user plane network element is a user plane network element controlled by the source session management network element and interfacing with the source base station.

[0058] Through the above method, the mobility management network element instructs the target intermediate session management network element to create the forwarding tunnel by sending the first indication information, which can improve the flexibility of creating the forwarding tunnel and the creation efficiency of the forwarding tunnel.

[0059] In a possible design, before the mobility management network element sends the first indication information to the target intermediate session management network element, the mobility management network element may first determine that a forwarding tunnel needs to be established; the mobility management network element may also obtain the first indication information from the source session management network element.

[0060] Through the above method, the mobility management network element can determine the first indication information in different ways, providing different ways to create a forwarding tunnel, which can be applied to different scenarios, ensuring a wider range of application scenarios.

[0061] In a possible design, if the mobility management network element receives a message for triggering a service request process from the source session management network element, the mobility management network element determines that a forwarding tunnel needs to be established.

[0062] Through the above method, a forwarding tunnel is created when a service request process needs to be triggered; the source session management network element can enable a session to be established through the forwarding tunnel, ensuring that the terminal device can receive data in a timely manner.

[0063] In a possible design, the mobility management network element can obtain the information of the target intermediate session management network element in multiple ways. Two of them are listed below:

[0064] First, the mobility management network element first obtains the location information of the terminal device, and then selects the information of the target intermediate session management network element according to the location information of the terminal device;

[0065] Second, the mobility management network element receives the information of the target intermediate session management network element from the source session management network element.

[0066] Through the above method, the information of the target intermediate session management network element is obtained in different ways, providing multiple ways to create a forwarding tunnel, making the application scenario of the communication method wider.

[0067] In a possible design, in addition to creating a forwarding tunnel, a tunnel between the target intermediate user plane network element and the anchor user plane network element can also be created. The specific process is as follows:

[0068] The mobility management network element receives session information from the source session management network element;

[0069] The mobility management network element sends the session information to the target intermediate session management network element, so that the target intermediate session management network element creates a tunnel between the target intermediate user plane network element and the anchor user plane network element;

[0070] Wherein, the session information includes at least one of the following: uplink tunnel information of the anchor user plane network element, information of the anchor session management network element; the anchor session management network element is a session management network element that controls the anchor user plane network element.

[0071] Through the above method, the data that needs to be transmitted between the data network and the terminal device can be transmitted through the tunnel between the target intermediate user plane network element and the anchor user plane network element, which can ensure that the terminal device can send and receive data in a timely manner and can ensure the service continuity of the terminal device.

[0072] In a possible design, the first indication information can be carried in the session information.

[0073] Through the above method, the session information and the first indication information can be sent together, which can effectively save signaling resources and improve efficiency.

[0074] In a possible design, the information of the source session management network element can be carried in the session information.

[0075] Through the above method, the session information and the information of the source session management network element can be sent together, which can effectively save signaling resources and improve efficiency.

[0076] Fourthly, an embodiment of the present invention provides a communication system. The beneficial effects can be referred to the descriptions in the first aspect and the second aspect, which will not be elaborated here. The communication system includes a target intermediate session management network element and a source session management network element;

[0077] Wherein, the target intermediate session management network element is used to obtain the information of the source session management network element; and send a first message to the source session management network element according to the information of the source session management network element;

[0078] The source session management network element is used to receive the first message from the target intermediate session management network element; and based on the first message, notify the source intermediate user plane network element to create the forwarding tunnel;

[0079] Wherein, the first message is used to establish a forwarding tunnel from the source intermediate user plane network element to the target intermediate user plane network element. The source intermediate user plane network element is a user plane network element controlled by the source session management network element and interfacing with the source base station, and the target intermediate user plane network element is a user plane network element controlled by the target intermediate session management network element and interfacing with the target base station.

[0080] In a possible design, before receiving the first message from the target intermediate session management network element, the source session management network element determines that a forwarding tunnel needs to be established; and sends the first indication information to the target intermediate session management network element, where the first indication information is used to instruct the target intermediate session management network element to create the forwarding tunnel.

[0081] In a possible design, the target intermediate session management network element obtains the first indication information from the source session management network element; and then, according to the first indication information, instructs the target intermediate user plane network element to create the forwarding tunnel.

[0082] In a possible design, the source session management network element sends session information to the target intermediate session management network element; where the session information includes at least one of the following: uplink tunnel information of the anchor user plane network element, information of the anchor session management network element; the anchor session management network element is the session management network element that controls the anchor user plane network element.

[0083] In a possible design, the target intermediate session management network element may also obtain session information from the source session management network element according to the information of the source session management network element; and then, based on the session information, create a tunnel between the target intermediate user plane network element and the anchor user plane network element.

[0084] In a possible design, the communication system further includes a mobility management network element, and the mobility management network element determines that a forwarding tunnel needs to be established. Optionally, the first indication information is sent to the target intermediate session management network element, where the first indication information is used to instruct the target intermediate session management network element to create the forwarding tunnel.

[0085] In a possible design, the mobility management network element receives a message for triggering a service request process from the source session management network element and determines that a forwarding tunnel needs to be established.

[0086] It should be understood that the names of the target intermediate session management network element, the source session management network element, and the mobility management network element in the communication system do not constitute a limitation on the device itself. In other networks, the target intermediate session management network element, the source session management network element, and the mobility management network element may also be other network elements with corresponding functions.

[0087] Fifth aspect, embodiments of the present application further provide a communication device, which is applied to a session management network element. The beneficial effects can be referred to the description in the first aspect and will not be elaborated here. The device has the function of implementing the behaviors in the method examples of the above first aspect. The function can be implemented by hardware or by hardware executing corresponding software. The hardware or software includes one or more modules corresponding to the above functions. In a possible design, the structure of the device includes a processing unit and a transceiver unit, and these units can execute the corresponding functions in the method examples of the above first aspect. For specific details, refer to the detailed description in the method examples and will not be elaborated here.

[0088] Sixth aspect, embodiments of the present application further provide a communication device, which is applied to a session management network element. The beneficial effects can be referred to the description in the second aspect and will not be elaborated here. The device has the function of implementing the behaviors in the method examples of the above second aspect. The function can be implemented by hardware or by hardware executing corresponding software. The hardware or software includes one or more modules corresponding to the above functions. In a possible design, the structure of the device includes a processing unit and a transceiver unit, and these units can execute the corresponding functions in the method examples of the above second aspect. For specific details, refer to the detailed description in the method examples and will not be elaborated here.

[0089] Seventh aspect, embodiments of the present application further provide a communication device, which is applied to a mobility management network element. The beneficial effects can be referred to the description in the third aspect and will not be elaborated here. The device has the function of implementing the behaviors in the method examples of the above third aspect. The function can be implemented by hardware or by hardware executing corresponding software. The hardware or software includes one or more modules corresponding to the above functions. In a possible design, the structure of the device includes a processing unit and a transceiver unit, and these units can execute the corresponding functions in the method examples of the above third aspect. For specific details, refer to the detailed description in the method examples and will not be elaborated here.

[0090] Eighth aspect, embodiments of the present application further provide a device, which is applied to a session management network element. The beneficial effects can be referred to the description in the first aspect and will not be elaborated here. The structure of the communication device includes a processor and a memory. The processor is configured to support the terminal to execute the corresponding functions in the method of the above first aspect. The memory is coupled to the processor and stores the necessary program instructions and data of the terminal. The structure of the communication device further includes a communication interface for communicating with other devices.

[0091] In a ninth aspect, an embodiment of the present application further provides a device, which is applied to a session management network element. The beneficial effects can be referred to the description in the second aspect and will not be elaborated here. The structure of the communication device includes a processor and a memory. The processor is configured to support the terminal to execute the corresponding functions in the method of the second aspect above. The memory is coupled to the processor and stores the necessary program instructions and data of the terminal. The structure of the communication device further includes a communication interface for communicating with other devices.

[0092] In a tenth aspect, an embodiment of the present application further provides a device, which is applied to a mobility management network element. The beneficial effects can be referred to the description in the third aspect and will not be elaborated here. The structure of the communication device includes a processor and a memory. The processor is configured to support the terminal to execute the corresponding functions in the method of the third aspect above. The memory is coupled to the processor and stores the necessary program instructions and data of the terminal. The structure of the communication device further includes a communication interface for communicating with other devices.

[0093] In an eleventh aspect, the present application further provides a computer-readable storage medium, in which instructions are stored. When it runs on a computer, the computer is enabled to execute the methods described in the above aspects.

[0094] In a twelfth aspect, the present application further provides a computer program product containing instructions. When it runs on a computer, the computer is enabled to execute the methods described in the above aspects.

[0095] In a thirteenth aspect, the present application further provides a computer chip. The chip is connected to a memory, and the chip is used to read and execute the software program stored in the memory to execute the methods described in the above aspects. BRIEF DESCRIPTION OF THE DRAWINGS

[0096] Figures 1A to 1C FIG. is a schematic diagram of a system architecture provided by the present application;

[0097] Figure 2 FIG. is a schematic diagram of a communication method provided by the present application;

[0098] Figure 3 FIG. is a schematic diagram of a communication method provided by the present application;

[0099] Figure 4 FIG. is a schematic diagram of a communication method provided by the present application;

[0100] Figure 5 FIG. is a schematic diagram of a communication method provided by the present application;

[0101] Figure 6 FIG. is a flowchart of a communication method provided by the present application;

[0102] Figures 7A to 7B A flowchart of a communication method provided for this application;

[0103] Figure 8 A flowchart of a communication method provided for this application;

[0104] Figure 9 A flowchart of a communication method provided for this application;

[0105] Figure 10 A schematic structural diagram of a device provided for this application;

[0106] Figure 11 A schematic structural diagram of a device provided for this application;

[0107] Figure 12 A schematic structural diagram of a device provided for this application;

[0108] Figure 13 A schematic structural diagram of a device provided for this application. Detailed implementation manners

[0109] In order to make the objectives, technical solutions and advantages of this application clearer, the following will further describe this application in detail with reference to the accompanying drawings. The specific operation methods in the method embodiments can also be applied to the device embodiments or system embodiments.

[0110] The following explains some terms in this application to facilitate the understanding of those skilled in the art.

[0111] 1. A communication system is used to connect a terminal device to a DN when the terminal device requests a service, and to implement the transmission of user plane data between the terminal device and the DN to implement the corresponding service. Among them, the communication system is divided into an access network (AN) and a core network. The access network is used to converge the terminal device into the core network; the core network is used to connect the terminal device to different DNs. According to the logical function division, the core network can be further divided into a control plane and a user plane.

[0112] In addition, it should be noted that this application does not limit the communication system standard, which can be a third-generation (3G) communication system, a fourth-generation (4G) communication system, a fifth-generation (5G) communication system, and a communication system evolved based on the 3G, 4G, and 5G communication systems.

[0113] 2. The control plane network element involved in this application is responsible for the logical functions of the control plane in the core network and can also be referred to as a control plane function (CPF) entity. It is a network element in the core network responsible for implementing control and management functions such as session management, access and mobility management, and policy control.

[0114] The control plane network elements involved in this application mainly include session management network elements and mobility management network elements.

[0115] The session management network element is responsible for session management functions, such as allocating user plane network elements for terminal devices and establishing sessions. For example, the session management network element can be a session management function (SMF) entity. After the session of the terminal device is established, one or more session management network elements can be included in the control plane path of the terminal device.

[0116] When the control plane path of the terminal device includes one session management network element, the session management network element can manage one or more user plane network elements included in the session of the terminal device.

[0117] When the control plane path of the terminal device includes multiple session management network elements, the session management network elements are divided into intermediate session management network elements and anchor session management network elements. Among them, the anchor session management network element controls the user plane network elements connected to the data network in the session of the terminal device. For example, the anchor session management network element can be an A-SMF (anchor SMF, anchor session management function) entity; the intermediate session management network element controls the user plane network elements connected to the base station in the session of the terminal device. For example, the intermediate session management network element can be an I-SMF (intermediate SMF, intermediate session management function) entity.

[0118] The mobility management network element is responsible for functions such as access management and mobility management of terminal devices. In practical applications, it includes the mobility management functions in the mobility management entity (MME) in the long term evolution (LTE) network framework and adds access management functions. For example, the mobility management network element can be an access and mobility management function (AMF) entity.

[0119] 3. The user plane network element involved in this application is mainly responsible for forwarding packet data, quality of service (QoS) control, charging information statistics, etc.

[0120] After the establishment of a session of a terminal device (such as a packet data unit (PDU) session), one or more user plane network elements may be included in the user plane path of the terminal device. According to the position of the user plane network element in the user plane path, the user plane network element can be divided into an intermediate user plane network element and an anchor user plane network element. Among them, the anchor user plane network element is a user plane network element connected to the data network. For example, the anchor user plane network element may be an A-UPF (anchor UPF, anchor user plane function) entity; the intermediate user plane network element is a user plane network element connected to the base station. For example, the intermediate user plane network element may be an I-UPF (intermediate UPF, intermediate user plane function) entity.

[0121] 4. The terminal device involved in this application, also known as a user equipment (UE), can be deployed on land, including indoor or outdoor, handheld or vehicle-mounted; it can also be deployed on water (such as a ship, etc.); it can also be deployed in the air (such as an airplane, a balloon, a satellite, etc.). The terminal device can be a mobile phone, a tablet computer (pad), a computer with wireless transceiver function, a virtual reality (VR) device, an augmented reality (AR) device, a wireless device in industrial control, a wireless device in self-driving, a wireless device in remote medical, a wireless device in smart grid, a wireless device in transportation safety, a wireless device in smart city, a wireless device in smart home, and so on.

[0122] 5. The access network device involved in this application provides access services for terminal devices, controls users to access the mobile communication network through the access network. The AN can be a radio access network (RAN) device or other AN devices. For example, the access network device can be a gNB, a Node B (NB), an evolved Node B (eNB), a radio network controller (RNC), a base station controller (BSC), a base transceiver station (BTS), a home base station (e.g., Home eNB, or Home Node B), a baseband unit (BBU), an access point (AP), a worldwide interoperability for microwave access base station (WiMAX BS), etc. This application does not limit this.

[0123] 6. The session involved in this application is a connection among terminal devices, access network devices, user plane network elements, and data networks, and is used to transmit user plane data between the terminal device and the data network.

[0124] It should be noted that the multiple involved in this application refers to two or more.

[0125] In addition, it should be understood that in the description of this application, terms such as "first" and "second" are only used for the purpose of distinguishing descriptions, and cannot be understood as indicating or implying relative importance, nor can they be understood as indicating or implying an order.

[0126] Figure 1A FIG. is a schematic diagram of a possible communication system applicable to the communication method provided by this application. The communication system includes a target intermediate session management network element, a source session management network element. Optionally, it further includes a target intermediate user plane network element controlled by the target intermediate session management network element and a source intermediate user plane network element controlled by the source session management network element. Optionally, the communication system may further include a mobility management network element.

[0127] In this communication system, the number of user plane network elements controlled by a session management network element can be one or multiple. For the convenience of description, Figure 1A one is used as an example for illustrative purposes in all.

[0128] Due to the mobility of the terminal device, the terminal device may move from the service area of the current session management network element (for ease of description, hereinafter referred to as the "source session management network element") to the service area of another session management network element (hereinafter referred to as the "target intermediate session management network element").

[0129] In the above case, to ensure the continuity of the terminal device session, a forwarding tunnel needs to be established between the source intermediate user plane network element controlled by the source session management network element and the target intermediate user plane network element controlled by the target intermediate session management network element, so as to ensure that the source intermediate user plane network element can send data to the target intermediate user plane network element through the forwarding tunnel.

[0130] In addition, the target intermediate user plane network element controlled by the target intermediate session management network element needs to establish a tunnel with the anchor point user plane network element to ensure that data in the data network can be sent to the base station through the target intermediate user plane network element, and then through the base station, the data is sent to the terminal device; the data of the terminal device can also be sent to the target intermediate user plane network element through the target base station, and then through the target intermediate user plane network element, the data is sent to the data network.

[0131] During the process of creating the forwarding tunnel in the communication system:

[0132] The target intermediate session management network element is used to obtain the information of the source session management network element; and send a first message to the source session management network element according to the information of the source session management network element.

[0133] The source session management network element is used to receive the first message from the target intermediate session management network element; and based on the first message, notify the source intermediate user plane network element to create the forwarding tunnel.

[0134] Wherein, the first message is used to establish a forwarding tunnel from the source intermediate user plane network element to the target intermediate user plane network element. The source intermediate user plane network element is a user plane network element controlled by the source session management network element and interfacing with the source base station, and the target intermediate user plane network element is a user plane network element controlled by the target intermediate session management network element and interfacing with the target base station.

[0135] In a possible implementation manner, the source session management network element may determine that the forwarding tunnel needs to be established before receiving the first message from the target intermediate session management network element; and then send the first indication information to the target intermediate session management network element, where the first indication information is used to instruct the target intermediate session management network element to create the forwarding tunnel.

[0136] Optionally, the target intermediate session management network element obtains the first indication information from the source session management network element; and then, according to the first indication information, instructs the target intermediate user plane network element to create the forwarding tunnel.

[0137] In a possible implementation manner, the source session management network element may further send session information to the target intermediate session management network element; wherein, the session information includes at least one of the following: uplink tunnel information of the anchor user plane network element, information of the anchor session management network element; the anchor session management network element is a session management network element that controls the anchor user plane network element.

[0138] Optionally, the target intermediate session management network element may also obtain session information from the source session management network element according to the information of the source session management network element; and then, based on the session information, create a tunnel between the target intermediate user plane network element and the anchor user plane network element.

[0139] Optionally, the target intermediate session management network element obtains the information of the source session management network element from the mobility management network element.

[0140] Optionally, the mobility management network element is used to obtain the information of the target intermediate session management network element; and then, according to the information of the target intermediate session management network element, send the information of the source session management network element to the target intermediate session management network element.

[0141] In a possible implementation manner, the mobility management network element sends the first indication information to the target intermediate session management network element, and the first indication information is used to instruct the target intermediate session management network element to create a forwarding tunnel from the source intermediate user plane network element to the target intermediate user plane network element, and the source intermediate user plane network element is a user plane network element controlled by the source session management network element and interfacing with the source base station.

[0142] Optionally, when the mobility management network element determines that the forwarding tunnel needs to be established, it sends the first indication information to the target intermediate session management network element.

[0143] Optionally, the mobility management network element obtains the first indication information from the source session management network element and sends the first indication information to the target intermediate session management network element.

[0144] Optionally, if the mobility management network element receives a message for triggering a service request process from the source session management network element, it determines that the forwarding tunnel needs to be established.

[0145] A possible implementation manner is that the mobility management network element receives session information from the source session management network element, and sends the session information to the target intermediate session management network element, so that the target intermediate session management network element creates a tunnel between the target intermediate user plane network element and the anchor user plane network element.

[0146] Based on Figure 1A the communication system shown, the embodiments of the present application also provide schematic diagrams of network architectures of two other possible communication systems, see Figure 1B and 1C shown. In the communication systems shown in Figure 1B and 1C both include an AMF entity, an SMF entity, and a UPF entity, and may also include a terminal device (taking the terminal device as a UE in the figure), an AN device, etc.

[0147] Among them, Figure 1A the source intermediate session network element and the mobility management network element in Figure 1B correspond to the I-SMF and AMF in Figure 1B respectively; the source intermediate user plane network element and the anchor user plane network element correspond to the I-UPF and A-UPF in

[0148] Figure 1A respectively. The source intermediate session network element and the mobility management network element in Figure 1C correspond to the A-SMF and AMF in Figure 1B respectively; the source intermediate user plane network element and the anchor user plane network element correspond to the I-UPF and A-UPF in

[0149] It should be understood that, Figure 1B and Figure 1C although the target intermediate session management network element and the target intermediate user plane network element are not shown in Figure 1B and Figure 1C respectively, the target intermediate session management network element and the target intermediate user plane network element are different from the SMF entity and the UPF entity in Figure 1B and Figure 1C respectively, and are the SMF entity and the UPF entity within the service range where the terminal device is located after moving.

[0150] For example, Figure 1B in the communication system shown, there are two SMF entities (A-SMF entity and I-SMF entity), two UPF entities (A-UPF entity and I-UPF entity), and the UE is located within the service area of the I-SMF entity.

[0151] For example, Figure 1C in the network architecture shown, there is one SMF entity, and the SMF entity controls the A-UPF entity connected to the data network, then Figure 1C the SMF entity in Figure 1C is the A-SMF entity, and the UE is located within the service area of the A-SMF entity.

[0152] It should be noted that Figure 1B and Figure 1C the RAN device, SMF entity, UPF entity, AMF entity, etc. in are just names, and the names do not limit the devices themselves. In the 5G network and other future networks, the network elements corresponding to the RAN device, SMF entity, UPF entity, AMF entity, and UDM can also have other names, and the embodiments of the present application do not make specific limitations on this.

[0153] For example, Figure 1B and Figure 1C in the network framework of , the RAN device communicates with the AMF entity through the N2 interface, the RAN device communicates with the UPF entity through the N3 interface, the UPF entity communicates with the SMF entity through the N4 interface, the UPF entity communicates with the UPF entity through the N9 interface, and the AMF entity communicates with the SMF entity through the N11 interface.

[0154] For the convenience of description, the present application uses Figure 1B and Figure 1C the communication system shown in as a specific embodiment to introduce the solution of the present application.

[0155] In Figure 1B and Figure 1C the communication system shown in , one SMF entity can control multiple UPF entities. Among them, the set of locations where the multiple UPF entities are located can constitute the service area of the SMF entity. The SMF entity controlling multiple UPF entities can also be referred to as the SMF entity corresponding to multiple UPF entities.

[0156] When the terminal device moves from the service area of the SMF entity on the current control plane path to the service area of other SMF entities, to facilitate the distinction between the two different SMF entities, the SMF entity on the current control panel path is called the source SMF entity, and the SMF entity in the area where the terminal device is located after moving is called the target I-SMF entity. In order to ensure the continuity of the terminal device, a session needs to be re-established, and then the source SMF entity needs to be switched to the target I-SMF entity. However, there is currently no solution for implementing the SMF entity switch. Therefore, the present application provides a communication method applicable to Figures 1A to 1C the system architecture shown in to implement the switch of the SMF entity.

[0157] In Figure 1BThe communication system shown contains two SMF entities, an I-SMF entity and an A-SMF entity. The terminal device is currently in the service area of the I-SMF entity. If the terminal device moves from the service area of the current I-SMF entity to the service area of another I-SMF entity, the source SMF entity is the I-SMF entity on the current control plane path, and the target I-SMF entity is the SMF entity in the area where the terminal device is located after moving; the source base station is the access network device on the current user plane path, and the target base station is the access network device that needs to be added to the user plane path after switching the SMF entity.

[0158] In the communication system as Figure 1C shown, there is an A-SMF entity. The terminal device is currently in the service area of the A-SMF entity. If the terminal device moves from the service area of the current A-SMF entity to the service area of another SMF entity, an SMF entity needs to be inserted as the I-SMF entity on the current control plane path. Then, the source SMF entity is the A-SMF entity, and the target I-SMF entity is the SMF entity that needs to be inserted currently; the source base station is the access network device on the current user plane path, and the target base station is the access network device that needs to be added to the user plane path after switching the SMF entity.

[0159] It should be noted that when the terminal device moves from the service area of the source SMF entity to the service area of the target I-SMF entity, the terminal device may be in the connected state, that is, there is a NAS signaling connection between the terminal device and the AMF; the terminal device may also be in the idle state, that is, there is no NAS signaling connection between the terminal device and the AMF. No matter what state the terminal device is in, the communication method provided in this application is applicable.

[0160] Based on Figure 1A 、 Figure 1B and Figure 1C the network architecture of the communication system shown, for the convenience of description, only the source session management network element is used as the source SMF entity, the source user plane network element is used as the source UPF entity, the target intermediate session management network element is used as the target I-SMF entity, the target intermediate user plane network element is used as the target I-UPF entity, the anchor point user plane network element is used as the A-UPF entity, and the mobility management network element is used as the AMF entity for illustration.

[0161] Specifically, the communication method provided in this application can be divided into two processes: Process 1, establishing a forwarding tunnel from the source UPF entity to the target I-UPF entity; Process 2, establishing a tunnel between the target I-UPF entity and the A-UPF entity.

[0162] The above two processes will be introduced separately below.

[0163] Procedure 1: Establish a forwarding tunnel from the source UPF entity to the target I-UPF entity.

[0164] When establishing the forwarding tunnel, the following two communication methods can be adopted:

[0165] First, the target I-SMF entity directly communicates and interacts with the source SMF entity.

[0166] Second, the target I-SMF entity and the source SMF entity communicate and interact through the AMF entity.

[0167] To clearly introduce the communication method provided by this application, the following separately introduces the two communication methods that can be adopted in Procedure 1:

[0168] Figure 2 This application provides an embodiment of a communication method, and this communication method adopts the first communication method in the above Procedure 1. As Figure 2 shown, the process of this method includes:

[0169] S201: The target I-SMF entity obtains information of the source SMF entity, and the source SMF entity is the SMF entity that controls the UPF entity of the interface with the source base station.

[0170] S202: The target I-SMF entity sends a first message to the source SMF entity according to the information of the source SMF entity; the source SMF entity receives the first message.

[0171] S203: The source SMF entity notifies the source I-UPF entity to create the forwarding tunnel based on the first message.

[0172] Among them, the first message is used to establish a forwarding tunnel from the source I-UPF entity to the target I-UPF entity. The source I-UPF entity is the UPF entity controlled by the source SMF entity and interfaced with the source base station, and the target I-UPF entity is the UPF entity controlled by the target I-SMF entity and interfaced with the target base station.

[0173] To enable the target I-SMF entity to communicate with the source SMF entity, first the target I-SMF entity needs to obtain information of the source SMF entity.

[0174] Optionally, the information of the source SMF entity may be the address information of the source SMF entity, or the ID of the source SMF entity, or the fully qualified domain name (FQDN) of the source SMF entity. Any information that can be used to identify the source SMF entity can be applied to the information of the source SMF entity in the embodiments of this application. In this way, it can be ensured that the target I-SMF entity can determine the source SMF entity through the information of the source SMF entity and can interact with the source SMF entity.

[0175] After the target I-SMF entity obtains the information of the source SMF entity, the target I-SMF entity may determine that the SMF entity needs to be switched currently and the forwarding tunnel needs to be established. That is to say, the information of the source SMF entity can be used as a message indicating the establishment of the forwarding tunnel. After the target I-SMF entity obtains the information of the source SMF entity, it determines that the forwarding tunnel needs to be established.

[0176] In a possible implementation manner, the source SMF entity determines that the forwarding tunnel needs to be established; the source SMF entity may send the first indication information to the target I-SMF entity, where the first indication information is used to instruct the target I-SMF entity to create the forwarding tunnel.

[0177] When the target I-SMF entity obtains the first indication information from the source SMF entity, the target I-SMF entity may determine that the forwarding tunnel needs to be established.

[0178] Specifically, the ways for the source SMF entity to determine that the forwarding tunnel needs to be established may include but are not limited to the following:

[0179] Way 1: When there is downlink data to be sent to the terminal device in the source SMF entity, the source SMF entity determines that the forwarding tunnel needs to be established; or, when there is downlink data to be sent to the terminal device in the source I-UPF entity, the source I-UPF entity sends a downlink data notification to the source SMF entity, and then the source SMF entity may determine the current downlink data to be sent to the terminal device and determine that the forwarding tunnel needs to be established.

[0180] Way 2: The source SMF entity sends a request message for requesting to establish a tunnel between the base station and the source I-UPF. Then, when the source SMF entity learns that the session needs to be switched to the target I-SMF, the source SMF entity determines that the forwarding tunnel needs to be established.

[0181] It should be noted that when the terminal device is in the connected state, if there is a situation where the SMF entity needs to be switched, there will be a handover of the base station. The target base station will allocate the indirect forwarding tunnel information corresponding to the target base station and send the allocated indirect forwarding tunnel information corresponding to the target base station to the AMF entity. Then, the AMF entity will send the indirect forwarding tunnel information to the target I-SMF entity. After receiving the indirect forwarding tunnel information, the target I-SMF entity can use the indirect forwarding tunnel information as an indication to create a forwarding tunnel, and the target I-SMF entity determines that the forwarding tunnel needs to be established.

[0182] When the terminal device is in the idle state, if there is downlink data to be sent to the terminal device in the source SMF entity or the source I-UPF entity, a message to establish an N3 tunnel is sent to the AMF. This message to establish an N3 tunnel triggers the AMF entity to notify the base station to page the terminal device. When the terminal device receives the paging, it sends a service request message to the AMF entity. That is to say, when the terminal device is in the idle state, the service request process is triggered by the source SMF entity, or the service request process is triggered because there is downlink data cached in the source SMF entity or the source I-UPF entity that needs to be sent to the terminal device.

[0183] The indirect forwarding tunnel is established when the terminal device is in the connected state because the source base station and the target base station (in this embodiment of the present application, taking the AN device as the base station, the source AN device and the target AN device are the source base station and the target base station respectively) cannot directly forward data. In order to ensure that the downlink data that has been sent to the source base station can be sent to the terminal device through the target base station, a forwarding tunnel is established from the source base station through the source I-UPF, the target I-UPF to the target base station. The indirect forwarding tunnel includes the forwarding tunnel from the source I-UPF to the target I-UPF.

[0184] When the terminal device is in the idle state, if the service request process is triggered because there is downlink data cached in the source SMF entity or the source I-UPF entity that needs to be sent to the terminal device, since the downlink data has been cached in the source I-SMF or the source I-UPF, in order to ensure that the data cached in the source I-SMF or the source I-UPF is sent to the terminal device, a forwarding tunnel from the source I-UPF to the target I-UPF also needs to be established.

[0185] When the target I-SMF entity determines that the forwarding tunnel needs to be established, the target I-SMF entity selects a UPF entity from the UPF entities it controls as the target I-UPF entity and instructs the target I-UPF entity to create the forwarding tunnel according to the first indication information.

[0186] When the target I-SMF entity instructs the target I-UPF entity to create the forwarding tunnel according to the first indication information, multiple methods can be adopted. Two of them are listed below:

[0187] Method 1: The target I-SMF entity sends a first indication message to the target I-UPF entity.

[0188] Method 2: The target I-SMF entity sends a second indication message to the target I-UPF entity, which is used to instruct the target I-UPF entity to create the forwarding tunnel.

[0189] Optionally, the first message may include the forwarding tunnel information corresponding to the target I-UPF entity. For example, the IP address or tunnel identifier of the forwarding tunnel. The above forwarding tunnel information is only an example, and any information that can identify the forwarding tunnel can be used as the forwarding tunnel information.

[0190] The forwarding tunnel information corresponding to the target I-UPF entity may be determined by the target I-SMF entity, and the target I-UPF entity is instructed to create the forwarding tunnel according to the forwarding tunnel information corresponding to the target I-UPF entity in the first indication information or the second indication message sent to the target I-SMF entity. It may also be that after receiving the first indication information or the second indication message, the target I-UPF entity determines the tunnel information corresponding to the target I-UPF entity and creates the forwarding tunnel, and the target I-UPF entity sends the forwarding tunnel information to the target I-SMF.

[0191] The target I-SMF entity determines the first message for establishing the forwarding tunnel from the source I-UPF entity to the target I-UPF entity, and sends the first message to the source SMF entity.

[0192] Optionally, the first message may include the forwarding tunnel information corresponding to the target I-UPF entity corresponding to the forwarding tunnel; the first message may also include an indication information for indicating whether the created forwarding tunnel is part of an indirect forwarding tunnel.

[0193] After receiving the first message, the source SMF entity notifies the source I-UPF entity to create the forwarding tunnel based on the first message.

[0194] Optionally, when the source SMF entity notifies the source I-UPF entity to create the forwarding tunnel, the source SMF entity may send the forwarding tunnel information corresponding to the target I-UPF in the first message to the source I-UPF.

[0195] Optionally, during the process of the source SMF entity notifying the source I-UPF entity to create the forwarding tunnel, the source SMF may obtain the forwarding tunnel information corresponding to the source I-UPF.

[0196] Specifically, the source SMF may obtain the forwarding tunnel information corresponding to the source I-UPF in the following two ways: Way 1: The source SMF allocates the forwarding tunnel information corresponding to the source I-UPF and sends the forwarding tunnel information corresponding to the source I-UPF to the source I-UPF; Way 2: The source SMF requests the source I-UPF to allocate the forwarding tunnel information corresponding to the source I-UPF and receives the forwarding tunnel information corresponding to the source I-UPF allocated by the source I-UPF.

[0197] Optionally, after the source I-UPF entity completes the creation of the forwarding tunnel, it may send a message to the source SMF entity to notify that the forwarding tunnel has been created. After the source SMF entity determines that the forwarding tunnel has been created, it may send a response message indicating the completion of the creation of the forwarding tunnel to the target I-SMF entity to notify that the forwarding tunnel has been created.

[0198] Optionally, in the response message, the source SMF sends the forwarding tunnel information corresponding to the source I-UPF to the target I-SMF.

[0199] To save resources, after creating the forwarding tunnel, the target I-SMF entity and the source SMF entity may set a forwarding tunnel release timer. When the forwarding tunnel release timer expires, the target I-SMF and the source SMF respectively notify the target I-UPF and the source I-UPF to release the forwarding tunnel.

[0200] The target I-SMF entity may set the forwarding tunnel release timer when sending the first message to the source SMF entity; it may also set the forwarding tunnel release timer after receiving the response message fed back by the source SMF entity; it may also set the forwarding tunnel release timer after instructing the target I-UPF entity to create the forwarding tunnel. The above ways of setting the forwarding tunnel release timer are all illustrative examples, and any way that can set the forwarding tunnel release timer during the process of creating the forwarding tunnel is applicable to the embodiments of the present application.

[0201] In the case where the forwarding tunnel release timer expires, the target I-SMF entity notifies the I-UPF entity to release the forwarding tunnel.

[0202] The source SMF entity may set the forwarding tunnel release timer when obtaining the first message from the target I-SMF entity; may also set the forwarding tunnel release timer after notifying the source I-UPF entity to create the forwarding tunnel; may also set the forwarding tunnel release timer when sending the response message to the target I-SMF. The above ways of setting the forwarding tunnel release timer are all illustrative examples, and any way that can set the forwarding tunnel release timer during the process of creating the forwarding tunnel is applicable to the embodiments of the present application.

[0203] In the case where the forwarding tunnel release timer expires, the source SMF entity notifies the source I-UPF entity to release the forwarding tunnel.

[0204] Figure 3 The embodiments of the present application provide a communication method, and this communication method adopts the second communication method in the above process one. As shown in the figure, the process of this method includes:

[0205] S301: The AMF entity obtains information of the target I-SMF entity.

[0206] S302: The AMF entity sends the information of the source SMF entity to the target I-SMF entity according to the information of the target I-SMF entity; the target I-SMF entity receives the information of the source SMF entity.

[0207] S303: The target I-SMF entity sends a first message to the source SMF entity according to the information of the source SMF entity; the source SMF entity receives the first message;

[0208] S304: The source SMF entity notifies the source I-UPF entity to create the forwarding tunnel based on the first message.

[0209] Wherein, the source SMF entity is the SMF entity that controls the UPF entity interfacing with the source base station, and the target I-SMF entity is the SMF entity that controls the target I-UPF entity interfacing with the target base station.

[0210] In the embodiment as Figure 3 shown, compared with the embodiment as Figure 2Similar to the embodiments shown, the target I-SMF entity also needs to obtain information of the source SMF entity, and send the first message to the source SMF entity according to the information of the source SMF entity. After receiving the first message, the source SMF entity notifies the source I-UPF entity to create the forwarding tunnel based on the first message. For the specific process, refer to the embodiment shown in Figure 2, and the repeated parts will not be elaborated.

[0211] In a possible implementation manner, the AMF entity sends first indication information to the target I-SMF entity, and the first indication information is used to instruct the target I-SMF entity to create a forwarding tunnel from the source I-UPF entity to the target I-UPF entity.

[0212] After the target I-SMF entity obtains the first indication information, the target I-SMF entity can determine that a forwarding tunnel needs to be established.

[0213] Specifically, there are many ways for the AMF entity to send the first indication information to the target I-SMF entity. Two of them are listed below for illustration.

[0214] Method 1: The AMF entity determines that the forwarding tunnel needs to be established;

[0215] In the case where the AMF entity determines that the forwarding tunnel needs to be established, the first indication information is generated and sent to the target I-SMF entity.

[0216] Specifically, if the AMF entity receives a message for triggering a service request process from the source SMF entity, the AMF entity determines that the forwarding tunnel needs to be established.

[0217] When the session of the terminal device is not active, at this time, the N3 tunnel between the base station corresponding to this session and the source I-UPF is not established. If there is downlink data to be sent to the terminal device on the source SMF entity or the source I-UPF, the source SMF entity sends a message for activating this session (i.e., a request message for creating an N3 tunnel) to the AMF entity, and currently the terminal device is located in the service area of the target I-SMF entity, then the AMF entity determines that the forwarding tunnel needs to be established and sends the first indication information to the target I-SMF entity. In this case, the service request process is triggered by the source SMF entity.

[0218] Among them, when the AMF entity obtains the information of the target I-SMF entity, it may first obtain the location information of the terminal device. After the AMF entity determines that the terminal device has moved out of the service area of the source I-SMF entity according to the location information of the terminal device, it selects the target I-SMF entity according to the location information of the terminal device.

[0219] Optionally, when the AMF entity obtains the information of the target I-SMF entity, it may also be that after the source SMF entity selects the target I-SMF entity, it sends the information of the target I-SMF entity to the AMF entity.

[0220] Method 2: The AMF entity obtains the first indication information from the source SMF entity.

[0221] The first indication information sent by the AMF entity to the target I-SMF entity may also be forwarded by the source SMF entity through the AMF entity to the target I-SMF entity.

[0222] When the source SMF entity determines that the forwarding tunnel needs to be established, it sends the first indication information to the AMF entity, and the first indication information is used to instruct the target I-SMF entity to create the forwarding tunnel.

[0223] Among them, for the method by which the source SMF entity determines that the forwarding tunnel needs to be established, reference may be made to the embodiments as Figure 2 shown, which will not be elaborated here.

[0224] After that, the method by which the target I-SMF entity determines that the forwarding tunnel needs to be established, creates the forwarding tunnel, and the source SMF entity creates the forwarding tunnel based on the first message is the same as the embodiments as Figure 2 shown, which will not be elaborated here.

[0225] To save resources, after creating the forwarding tunnel, the target I-SMF entity and the source SMF entity may set a forwarding tunnel release timer, and when the forwarding tunnel release timer expires, the forwarding tunnel is released. For the description of the forwarding tunnel release timer, reference may be made to the same embodiments as Figure 2 shown, which will not be elaborated here.

[0226] Process 2: Establish a tunnel between the target I-UPF entity and the A-UPF entity.

[0227] When establishing a tunnel between the target I-UPF entity and the A-UPF entity, the following two communication methods may be adopted:

[0228] First, the target I-SMF entity directly communicates and interacts with the source SMF entity;

[0229] Second, communication and interaction are carried out between the target I-SMF entity and the source SMF entity through the AMF entity.

[0230] To clearly introduce the communication method provided by this application, the following separately introduces two communication methods that can be adopted in Process 2:

[0231] Figure 4 This application provides an embodiment of a communication method, and this communication method adopts the first communication method in the above Process 2. As Figure 4 shown, the process of this method includes:

[0232] S401: The source SMF entity sends the session information to the target I-SMF entity; the target I-SMF entity obtains the session information from the source SMF entity.

[0233] S402: The target I-SMF entity creates a tunnel between the target I-UPF entity and the A-UPF entity based on the session information.

[0234] Wherein, the session information includes at least one of the following: the uplink tunnel information of the A-UPF entity, the information of the A-SMF entity; the A-SMF entity is the SMF entity that controls the A-UPF entity.

[0235] The target I-SMF entity can determine the address information of the source SMF entity according to the information of the source SMF entity, and can send a message for requesting a session message to the source SMF entity through the address information of the source SMF entity.

[0236] After receiving the message for requesting a session message, the source SMF entity sends the session information to the target I-SMF entity.

[0237] After receiving the session information, the target I-SMF entity can create a tunnel between the target I-UPF entity and the A-UPF entity.

[0238] Among them, the session information may be session context information. Among them, the session information includes at least one of the uplink tunnel information of the A-UPF entity and the information of the A-SMF entity. When the session information contains the uplink tunnel information of the A-UPF entity, the target I-SMF entity may send the uplink tunnel information of the A-UPF entity to the target I-UPF entity to create an uplink tunnel between the target I-UPF entity and the A-UPF entity; when the session information contains the information of the A-SMF entity, the target I-SMF entity may send the downlink tunnel information of the target I-UPF to the A-SMF entity, and the A-SMF entity may send the downlink tunnel information of the target I-UPF entity to the A-UPF entity, thereby creating a downlink tunnel from the A-UPF to the I-UPF.

[0239] Figure 5 This application embodiment provides a communication method, and this communication method adopts the second communication method in the above process two. As Figure 5 shown, the process of this method includes;

[0240] S501: The source SMF entity sends session information to the AMF entity; the AMF entity receives the session information.

[0241] S502: The AMF entity sends the session information to the target I-SMF entity; the target I-SMF entity network element receives the session information.

[0242] S503: The target I-SMF entity creates a tunnel between the target I-UPF entity and the A-UPF entity based on the session information.

[0243] Among them, the session information includes at least one of the following: the uplink tunnel information of the A-UPF entity, the information of the A-SMF entity; the A-SMF entity is the SMF entity that controls the A-UPF entity.

[0244] Optionally, the session information may be encapsulated in a transparent container, and the AMF entity may not parse the session information in the transparent container.

[0245] In the embodiment as Figure 5 shown, the AMF entity has a forwarding function and sends the session message of the source SMF entity to the target I-SMF entity. Among them, the description of the session information can be referred to the embodiment as Figure 4 shown, which will not be elaborated here.

[0246] It should be noted that in the above two processes, the target I-SMF entity needs to obtain the information of the source SMF entity, and there are various ways to obtain the information of the source SMF entity. For example, the information of the source SMF entity can be pre-stored in the AMF entity, and when the SMF entity needs to be switched, the AMF entity sends the information of the source SMF entity to the target I-SMF entity; or, the source SMF entity can also send the information of the source SMF entity to the AMF entity, and then the AMF entity forwards the information of the source SMF entity to the target I-SMF entity, and the information of the source SMF entity is encapsulated in a transparent container together with other session information.

[0247] It should be understood that the two communication methods in Process 1 can be arbitrarily combined with the two communication methods in Process 2. For example, when creating the forwarding tunnel, the communication method shown in Figure 2 is adopted, and when creating the tunnel between the target I-UPF entity and the A-UPF entity, the communication method shown in Figure 4 is adopted. Another example is that when creating the forwarding tunnel, the communication method shown in Figure 3 is adopted, and when creating the tunnel between the target I-UPF entity and the A-UPF entity, the communication method shown in Figure 5 is adopted. Another example is that when creating the forwarding tunnel, the communication method shown in Figure 2 is adopted, and when creating the tunnel between the target I-UPF entity and the A-UPF entity, the communication method shown in Figure 4 is adopted.

[0248] It should be noted that Process 1 and Process 2 can be carried out simultaneously or successively.

[0249] Among them, when the source SMF entity sends information to the AMF entity or the target I-SMF entity, multiple pieces of information can be sent in one signaling. For example, when the source SMF entity sends session information to the AMF entity or the target I-SMF entity, it can carry the information of the source SMF entity in the session information, or carry the first indication information in the session information, or carry both the information of the source SMF entity and the first indication information in the session information.

[0250] When the AMF entity sends information to the target I-SMF entity, it can also include multiple pieces of information in one signaling message. For example, when the AMF entity sends the session information to the target I-SMF entity, it can carry the information of the source SMF entity in the session information, or carry the first indication information in the session information, or carry both the information of the source SMF entity and the first indication information in the session information.

[0251] The following will use the communication method shown in the embodiments of this application Figures 2 to 5 applied to a specific scenario. Through the following Embodiment 1 to Embodiment 4, the communication method of this application will be further introduced.

[0252] Embodiment 1 is applied to the network framework as shown in Figure 1B where the source SMF entity is the source I-SMF entity. When the UE is in the connected state, the UE moves out of the service area of the source I-SMF entity and into the service area of the target I-SMF entity. As shown in Figure 6 the specific process of Embodiment 1 includes:

[0253] S601: The source base station sends a handover request message to the AMF entity, and the AMF entity receives the handover request message. The handover request message includes the session identifier of the session to be handed over (for example, PDU Session ID), the SM N2 request message corresponding to the session to be handed over, and the location information of the UE. The SM N2 request message corresponding to the session to be handed over indicates whether a forwarding tunnel needs to be created during the handover and whether the release of the forwarding tunnel needs to pass through the core network.

[0254] S602: The AMF entity determines the source I-SMF entity corresponding to the session according to the session identifier of the session to be handed over. The AMF entity sends a session update request message to the source I-SMF entity. The source I-SMF entity receives the session update request message. In the session update request message, the AMF entity sends the session identifier of the session to be handed over, the SM N2 message corresponding to the session to be handed over, and the location information of the UE to the source I-SMF entity.

[0255] S603: The source I-SMF entity determines whether the UE has moved out of the service area of the source I-SMF entity according to the location information of the UE and the service area of the source I-SMF entity. If the UE has moved out of the service area of the source I-SMF entity, the source I-SMF entity sends a first response message to the AMF entity; the AMF entity receives the first response message.

[0256] The first response message may include indication information for indicating that the AMF entity selects a target I-SMF entity; it may also include information about the target I-SMF entity, and the target I-SMF entity is selected by the source I-SMF entity according to the location information of the UE.

[0257] The first response message further includes session information, and the session information includes at least one of the uplink tunnel information of the A-UPF entity and the information of the A-SMF.

[0258] Optionally, the session information further includes information about the source I-SMF entity (for example, the identification information or the address information of the I-SMF entity).

[0259] In a specific implementation, the source I-SMF entity may encapsulate the session information in a transparent container and send it to the AMF entity, and the AMF entity may forward the transparent container to the target I-SMF entity without parsing the content in the transparent container.

[0260] Optionally, if the source I-SMF entity receives the SM N2 message corresponding to the session to be switched sent by the AMF entity, since the AMF entity does not save the SM N2 message, the source I-SMF entity may also send the SM N2 message back to the AMF entity when sending the response message.

[0261] S604: If the AMF entity receives the indication information for indicating that the AMF entity selects a target I-SMF entity, the AMF entity selects a target I-SMF entity according to the location information of the UE.

[0262] S605: The AMF entity sends a session establishment request to the target I-SMF entity, and sends the SM N2 request message corresponding to the session to be switched, the location information of the UE, and the session information obtained from the source I-SMF entity to the target I-SMF entity; the target I-SMF entity receives the session establishment request and obtains the SM N2 request message corresponding to the session to be switched, the location information of the UE, and the session information obtained from the source I-SMF entity.

[0263] Optionally, the AMF entity sends the information of the source I-SMF entity to the target I-SMF entity.

[0264] S606: The target I-SMF entity selects a target I-UPF entity according to the location information of the UE, and sends the uplink tunnel information of the A-UPF entity in the session information to the target I-UPF entity; the target I-UPF entity receives the uplink tunnel information of the A-UPF entity and establishes an uplink tunnel from the target I-UPF entity to the A-UPF entity based on the uplink tunnel information of the A-UPF entity.

[0265] In S606, by establishing an uplink tunnel from the target I-UPF entity to the A-UPF entity, after the UE switches to the target base station, the I-UPF entity can send the uplink data packets of the UE received from the target base station to the A-UPF entity through this uplink tunnel.

[0266] In specific implementation, in S606, the target I-SMF entity can also notify the I-UPF entity to create an N3 uplink tunnel and the downlink tunnel of the target I-UPF entity facing the N9 interface. After S606 is completed, the target I-SMF entity obtains the N3 interface uplink tunnel information of the target I-UPF entity and the downlink tunnel information of the target I-UPF entity facing the N9 interface.

[0267] Optionally, the target I-SMF determines whether an indirect forwarding tunnel can be established according to the indication of whether a forwarding tunnel needs to be created and whether the forwarding tunnel needs to pass through the core network in the SM N2 request message.

[0268] S607: The target I-SMF entity sends a second response message to the AMF entity, and the AMF entity receives this second response message. The second response message includes the SM N2 response message sent by the target I-SMF entity to the target base station. The SM N2 response message includes the N3 uplink tunnel information of the target I-UPF entity and the indication of whether indirect forwarding tunnel is supported.

[0269] S608: The AMF entity sends a handover request to the target base station, and sends the SM N2 response message sent by the target I-SMF entity to the target base station in this handover request. The target base station receives this handover request and obtains this SM N2 response message.

[0270] S609: The target base station sends a handover request response to the AMF entity, and the AMF entity receives this handover request response; if an indirect forwarding tunnel needs to be established, the target base station allocates indirect forwarding tunnel information and sends the indirect forwarding tunnel information to the AMF entity; the AMF entity receives this indirect forwarding tunnel information.

[0271] S610: The AMF entity sends the indirect forwarding tunnel information of the target base station to the target I-SMF entity, and the target I-SMF entity receives this indirect forwarding tunnel information.

[0272] S611: The target I-SMF entity determines that an indirect forwarding tunnel needs to be established based on the indirect forwarding tunnel information sent by the target base station. The target I-SMF entity sends the indirect forwarding tunnel information of the target base station to the target I-UPF entity and instructs the target I-UPF to create an indirect forwarding tunnel, including creating a downlink forwarding tunnel and a forwarding tunnel from the target I-UPF entity to the target base station; the target I-UPF receives the indirect forwarding tunnel information and creates an indirect forwarding tunnel.

[0273] Optionally, the target I-SMF entity allocates the indirect forwarding tunnel information corresponding to the target I-UPF and sends the indirect forwarding tunnel information corresponding to the target I-UPF to the target I-UPF; or the target I-SMF entity requests the target I-UPF to allocate the indirect forwarding tunnel information, and the target I-UPF sends the indirect forwarding tunnel information to the target I-SMF.

[0274] In S611, the target I-SMF entity obtains the forwarding tunnel information of the target I-UPF entity and includes the forwarding tunnel information corresponding to the target I-UPF entity in the first message. The forwarding tunnel information of the target I-UPF entity can be allocated by the target I-SMF entity or by the target I-UPF entity. Optionally, the first message may further include an indirect forwarding tunnel indication for indicating that the forwarding tunnel from the source I-UPF to the target I-UPF is part of the indirect forwarding tunnel.

[0275] S612: The target I-SMF entity obtains the address information of the source I-SMF entity based on the information received from the source I-SMF entity, such as the uniform resource locator (URL) providing the session service, and sends a first message to the source I-SMF entity. This first message is used to request the source I-SMF entity to create a forwarding tunnel between the source I-UPF entity and the target I-UPF entity, and the target I-SMF entity sends the indirect forwarding tunnel information corresponding to the target I-UPF entity to the source I-SMF entity; the source I-SMF entity receives this first message and the indirect forwarding tunnel information corresponding to the target I-UPF entity.

[0276] S613: The source I-SMF entity sends the forwarding tunnel information corresponding to the target I-UPF entity to the source I-UPF entity and requests the source I-UPF entity to create the forwarding tunnel; the source I-UPF entity receives the forwarding tunnel information corresponding to the target I-UPF entity and creates a forwarding tunnel.

[0277] Optionally, according to the indirect forwarding tunnel indication in the first message, the source I-SMF obtains the indirect forwarding tunnel information corresponding to the source I-UPF entity. The source I-SMF entity allocates the indirect forwarding tunnel information corresponding to the source I-UPF and sends the indirect forwarding tunnel information corresponding to the source I-UPF to the source I-UPF; or the source I-SMF entity requests the source I-UPF to allocate the indirect forwarding tunnel information, and the source I-UPF sends the indirect forwarding tunnel information to the source I-SMF.

[0278] S614: The source I-SMF entity sends the forwarding tunnel information corresponding to the source I-UPF entity to the target I-SMF entity, and the target I-SMF entity receives the forwarding tunnel information corresponding to the source I-UPF entity.

[0279] S615: The target I-SMF entity sends the forwarding tunnel information corresponding to the source I-UPF entity to the AMF entity; the AMF entity receives the forwarding tunnel information corresponding to the source I-UPF entity.

[0280] S616: The AMF entity sends a handover command to the source base station, and this message carries the forwarding tunnel information corresponding to the source I-UPF entity; the source base station receives the handover command and obtains the forwarding tunnel information corresponding to the source I-UPF entity.

[0281] So far, it is the handover preparation phase. An indirect forwarding tunnel between the target base stations is established during the handover preparation phase, and the path of the indirect forwarding tunnel is: source base station –> source I-UPF entity –> destination I-UPF entity –> target base station.

[0282] S617: After the handover preparation is completed, the handover execution process will be performed. During the handover process, the air interface of the UE is switched from the source base station to the target base station, and the downlink tunnel of the A-UPF entity is switched from the source I-UPF entity to the target I-UPF entity sent. The details of the handover execution process are described in the 5G related protocol and will not be elaborated in this embodiment of the present application.

[0283] Embodiment 2: In Embodiment 1, it is selected that the target I-SMF entity is selected by the source SMF entity or the source SMF entity instructs the AMF entity to select. In fact, it can also be selected by the AMF entity without the source SMF entity sending an indication. Embodiment 2 provides a method for the AMF entity to select the target I-SMF entity.

[0284] In Embodiment 2, two methods for obtaining session information are also provided:

[0285] Method 1: The AMF entity obtains the session information from the source I-SMF entity and sends the session information to the target I-SMF entity.

[0286] In the second method, the AMF entity sends the information of the source I-SMF entity to the target I-SMF entity, and the target I-SMF entity obtains the session information from the source I-SMF entity.

[0287] As Figure 7A shown, a communication method provided by an embodiment of the present application adopts the first method for obtaining session information as described above. As shown in the figure, the process of this method includes;

[0288] S701: The same as S601 in Embodiment 1.

[0289] S702: The AMF entity selects a target I-SMF entity according to the service area of the source I-SMF entity and the location information of the UE.

[0290] Among them, the information of the service area of the source I-SMF entity can be configured on the AMF entity or in a network repository function (NRF), and the AMF entity obtains the information of the service area of the source I-SMF entity from the NRF entity.

[0291] S703: After the AMF entity selects the target I-SMF entity, the AMF entity sends the session identifier of the session to be switched to the source I-SMF entity, requesting the source I-SMF entity to send the session information to the AMF entity.

[0292] Among them, the session information includes at least one of the uplink tunnel information of the A-UPF entity and the information of the A-SMF.

[0293] S704: The source I-SMF entity sends the session information to the AMF entity.

[0294] Optionally, the session information further includes the information of the source I-SMF entity, such as the address information or identifier information of the source I-SMF entity. The source I-SMF entity can encapsulate the session information in a transparent container and send it to the AMF entity, and then send it to the target I-SMF entity through the AMF entity.

[0295] S705: The AMF entity sends a session establishment request to the target I-SMF entity, and sends the session information received from the source I-SMF entity to the target I-SMF entity.

[0296] Optionally, the AMF entity sends the information of the source I-SMF entity to the target I-SMF entity.

[0297] S706 to 717 are the same as S606 to 617 in Embodiment 1, and will not be described herein again.

[0298] As Figure 7BAs shown, a communication method provided by an embodiment of the present application adopts the second method for obtaining session information. As shown in the figure, the process of this method includes;

[0299] S701: The same as S601 in Embodiment 1.

[0300] S702: The AMF entity selects a target I-SMF entity according to the service area of the source I-SMF entity and the location information of the UE.

[0301] Among them, the service area of the source I-SMF entity can be configured on the AMF entity or in the NRF entity, and the AMF entity obtains the service area of the source I-SMF entity from the NRF entity.

[0302] S703: After the AMF entity selects the target I-SMF entity, it sends a session establishment request to the target I-SMF entity and sends the information of the source I-SMF entity to the target I-SMF entity; the target I-SMF entity receives the session establishment request and obtains the information of the source I-SMF entity.

[0303] S704: The target I-SMF entity determines the address information of the source I-SMF entity according to the information of the source I-SMF entity and sends a request message to the source I-SMF entity to request session information.

[0304] Among them, the session information includes at least one of the uplink tunnel information of the A-UPF entity and the information of the A-SMF.

[0305] S705: The source I-SMF entity receives the request message, and the source I-SMF entity sends session information to the target I-SMF entity.

[0306] S706 to 717 are the same as S606 to 617 in Embodiment 1 and will not be elaborated here.

[0307] Embodiment 3 is applied to the network architecture as shown in Figure 1B When the UE is in the idle state and needs to switch the SMF entity during the service request process. In Embodiment 3, the target I-SMF entity also needs to obtain the information of the source I-SMF entity. The method for the target I-SMF entity to obtain the information of the source I-SMF entity can refer to Embodiment 1 and Embodiment 2. Optionally, the target I-SMF entity can also obtain session information. The method for the target I-SMF entity to obtain session information can refer to Embodiment 1 and Embodiment 2.

[0308] In Embodiment 3, when the target I-SMF entity receives the first indication information, it determines that a forwarding tunnel needs to be established. In Embodiment 3, the first indication information may be sent by the AMF entity to the target I-SMF entity, or the source I-SMF entity may send the first indication information to the target I-SMF entity through the AMF entity.

[0309] As Figure 8 shown, a communication method provided by an embodiment of the present application, the process of the method includes:

[0310] S801: The UE sends a service request message to the AMF entity; the message includes the session identifier of the session to be activated and the location information of the UE, and the AMF entity receives the service request message.

[0311] S802 to S805: The AMF entity obtains information about the target I-SMF entity and sends a session establishment request to the target I-SMF entity; the target I-SMF entity obtains information about the source I-SMF entity and the first indication information.

[0312] Optionally, in S802 to S805, the target I-SMF entity may also obtain session information. Among them, the methods for the AMF entity to obtain the target I-SMF entity, the target I-SMF entity to obtain information about the source I-SMF entity, and the target I-SMF entity to obtain session information are the same as those in Embodiment 1 and Embodiment 2, and will not be elaborated here.

[0313] Among them, there are two ways for the target I-SMF entity to obtain the first indication information, which are specifically as follows:

[0314] (1) The source I-SMF entity determines whether a forwarding tunnel needs to be established.

[0315] When the source I-SMF entity determines whether a forwarding tunnel needs to be established, it may be determined according to whether the service request process is triggered. If the source I-SMF triggers the service request process, it is determined that a forwarding tunnel needs to be established; it may also be determined according to whether there is downlink data to be sent to the UE cached in the source I-SMF entity or the source I-UPF entity. If there is downlink data to be sent to the UE cached in the source I-SMF entity or the source I-UPF entity, the source I-SMF entity determines that a forwarding tunnel needs to be established.

[0316] In this way, the source I-SMF entity needs to send the first indication information. Specifically, the AMF entity may obtain session information from the source I-SMF entity (for example, Figure 6 shown in S602, S603, and Figure 7AWhen the source I-SMF entity (such as S703 and S704 shown) sends the first indication information to the AMF entity carried in the session information; then, the AMF entity sends the first indication information to the target I-SMF entity in the session establishment request (for example, in Figure 6 S605 shown, and Figure 7A S705 shown is executed).

[0317] The first indication information can be encapsulated with the session information in a transparent container and sent to the target I-SMF entity through the AMF entity, and the AMF entity does not need to parse the content of the transparent container.

[0318] If the target I-SMF entity directly obtains the session information from the source I-SMF entity (such as Figure 7B S704 and S705 shown), the source I-SMF entity can directly send the first indication information to the target I-SMF entity.

[0319] (2) The AMF entity determines whether a forwarding tunnel needs to be established.

[0320] When the AMF entity determines whether a forwarding tunnel needs to be established, it can be determined according to whether the source I-SMF entity corresponding to the session triggers the service request process. When the service request process is triggered by the source I-SMF entity corresponding to the session, the AMF entity determines that a forwarding tunnel needs to be established. For example, when the AMF entity receives a message from the source SMF entity for triggering the service request process, it determines that a forwarding tunnel needs to be established.

[0321] When the AMF entity determines that a forwarding tunnel needs to be established, it needs to send the first indication information to the target I-SMF entity. Specifically, the AMF entity can carry the first indication information in the session establishment request when sending the session establishment request to the target I-SMF entity (for example, in Figure 6 S605 shown, Figure 7A S705 shown, and Figure 7B S703 shown is executed).

[0322] S806: The target I-SMF entity selects a target I-UPF entity according to the UE location information; after receiving the first indication information, the target I-SMF entity carries the first indication information or the second indication information in the N4 session establishment request message sent to the target I-UPF entity, indicating the target I-UPF entity to create the forwarding tunnel; the target I-UPF entity receives the N4 session establishment request message and obtains the first indication information or the second indication information.

[0323] In S806, the target I-SMF entity obtains the forwarding tunnel information corresponding to the target I-UPF entity, and includes the forwarding tunnel information corresponding to the target I-UPF entity in the first message.

[0324] Among them, when the target I-SMF entity obtains the forwarding tunnel information corresponding to the target I-UPF entity, the following two methods can be adopted. Method 1: The target I-SMF entity allocates the forwarding tunnel information corresponding to the target I-UPF entity, and sends the forwarding tunnel information corresponding to the target I-UPF entity to the target I-UPF. Method 2: The target I-SMF requests the target I-UPF entity to allocate the forwarding tunnel information corresponding to the target I-UPF entity, and the target I-UPF sends the forwarding tunnel information to the target I-SMF.

[0325] If the target I-SMF entity obtains the session message in S802 to S805, and the session message includes the uplink tunnel information of the A-UPF entity, then in S806, the target I-SMF entity sends the uplink tunnel information of the A-UPF entity to the target I-UPF entity to create a tunnel between the target I-UPF entity and the A-UPF entity.

[0326] S807: The target I-SMF entity interacts with the A-SMF entity to establish a downlink tunnel between the A-UPF entity and the target I-UPF entity.

[0327] S808: If the target I-SMF entity receives the first indication information, determines the address information of the source I-SMF entity according to the information of the source I-SMF entity, and sends the first message to the source I-SMF entity. The first message includes the forwarding tunnel information corresponding to the target I-UPF; the source I-SMF entity receives the first message.

[0328] Optionally, the first message further includes an indication of a non-indirect forwarding tunnel, which is used to indicate that the forwarding tunnel is not part of an indirect forwarding tunnel.

[0329] S809: The source I-SMF entity sends the forwarding tunnel information corresponding to the target I-UPF to the source I-UPF entity, instructing to create a forwarding tunnel from the source I-UPF entity to the target I-UPF entity; the source I-UPF entity receives the forwarding tunnel information corresponding to the target I-UPF and creates a forwarding tunnel from the source I-UPF entity to the target I-UPF entity.

[0330] S810: After creating the forwarding tunnel, the source I-SMF entity sends a response message to the target I-SMF entity; the target I-SMF entity receives the response message and determines that the source I-SMF has created the forwarding tunnel.

[0331] S811: The source I-SMF entity and the target I-SMF entity respectively set up a forwarding tunnel release timer.

[0332] S812: The target I-SMF entity interacts through the AMF entity with the target base station to establish an uplink and downlink tunnel between the target base station and the target I-UPF entity. The specific implementation method can refer to the description in the existing protocol, and will not be elaborated in the embodiments of this application.

[0333] S813: When the forwarding tunnel release timer expires, the source I-SMF entity notifies the source I-UPF entity to release the forwarding tunnel; the target I-SMF entity notifies the target I-UPF entity to release the forwarding tunnel.

[0334] It should be noted that S807 can also be executed after S809, that is, first create a forwarding tunnel between the source I-UPF and the target I-UPF, and then establish a tunnel between the target I-UPF and the A-UPF; S807 can also be executed before step 806, that is, first establish a downlink tunnel from the A-UPF to the target I-UPF, and then establish an uplink tunnel from the target I-UPF to the A-UPF. The embodiments of this application do not make any limitations.

[0335] Embodiment 4 is applied to the network architecture as Figure 1C shown, where the source SMF entity is the A-SMF entity, the UE moves out of the service area of the A-SMF entity and moves into the service area of the target I-SMF entity; the target I-SMF needs to be inserted on the control plane path of the UE. In Embodiment 4, the target I-SMF entity also needs to obtain the information of the A-SMF entity. The method for the target I-SMF entity to obtain the information of the A-SMF entity can refer to the methods for obtaining the source I-SMF entity in Embodiment 1 and Embodiment 2.

[0336] As Figure 9 shown, a communication method provided by the embodiments of this application, the process of this method includes:

[0337] S901: The UE sends a service request message to the AMF entity; the session identifier of the session to be activated and the location information of the UE are included in this message, and the AMF entity receives this service request message.

[0338] S902 to S905: The AMF entity obtains the information of the target I-SMF entity and sends a session establishment request to the target I-SMF entity; the target I-SMF entity obtains the information of the A-SMF entity and the first indication information.

[0339] Optionally, in S902 to S905, the target I-SMF entity may also obtain session information from the A-SMF entity. Among them, the methods for the AMF entity to obtain information of the target I-SMF entity, the target I-SMF entity to obtain information of the A-SMF entity, and the target I-SMF entity to obtain session information are similar to those in Embodiment 1 and Embodiment 2, and will not be elaborated here. It should be noted that the A-SMF entity corresponds to the source SMF entity in Embodiment 1 and Embodiment 2. Therefore, the method for obtaining information of the A-SMF entity is similar to the method for obtaining information of the source SMF entity in Embodiment 1 and Embodiment 2.

[0340] Optionally, in S902 to S905, the target I-SMF entity also obtains first indication information, where the A-SMF entity corresponds to the source SMF entity in Embodiment 3, and the method for obtaining the first indication information is similar to that in Embodiment 3.

[0341] S906: The target I-SMF entity selects a target I-UPF entity according to the UE location information; after receiving the first indication information, the target I-SMF entity carries the first indication information or the second indication information in the N4 session establishment request message sent to the target I-UPF entity to instruct the target I-UPF entity to create the forwarding tunnel; the target I-UPF entity receives the N4 session establishment request message and obtains the first indication information or the second indication information..

[0342] In S906, the target I-SMF entity obtains the forwarding tunnel information corresponding to the target I-UPF entity and includes the forwarding tunnel information corresponding to the target I-UPF entity in the second message.

[0343] Among them, the manner in which the target I-SMF entity obtains the forwarding tunnel information corresponding to the target I-UPF entity can refer to the manner in which the target I-SMF entity obtains the forwarding tunnel information corresponding to the target I-UPF entity in Embodiment 2, and will not be elaborated here.

[0344] If the target I-SMF entity obtains session messages in S902 to S905, then in S906, the target I-SMF entity sends the uplink tunnel information of the A-UPF entity to the target I-UPF entity to create a tunnel between the target I-UPF entity and the A-UPF entity.

[0345] S907: The target I-SMF entity sends a second message to the A-SMF entity; the source I-SMF entity receives the first message.

[0346] Optionally, the target I-SMF entity carries indication information for establishing a forwarding tunnel in the second message to instruct the establishment of a forwarding tunnel from the source I-UPF entity to the target I-UPF entity.

[0347] Optionally, the second message further includes the downlink tunnel information of the target I-UPF entity, and the downlink tunnel information of the target I-UPF entity is used to establish a tunnel between the target I-UPF and the A-UPF.

[0348] S908: If a forwarding tunnel needs to be established, the A-SMF entity sends the forwarding tunnel information corresponding to the target I-UPF entity included in the second message to the source I-UPF entity, and sends an indication message to the source I-UPF entity to instruct the source I-UPF entity to create a forwarding tunnel; the source I-UPF entity receives the forwarding tunnel information and the indication message corresponding to the target I-UPF entity, and creates a forwarding tunnel.

[0349] Optionally, the A-SMF entity sends the downlink tunnel information of the target I-UPF entity to the A-UPF entity to establish a tunnel between the target I-UPF entity and the A-UPF entity.

[0350] S909: After the A-SMF entity determines that the forwarding tunnel is created, the A-SMF entity sends a response message to the target I-SMF entity to notify the target I-SMF entity that the forwarding tunnel is created, and the target I-SMF entity receives the response message and determines that the A-SMF has created a forwarding tunnel.

[0351] S910: The A-SMF entity and the target I-SMF entity respectively set a forwarding tunnel release timer.

[0352] S911: The target I-SMF entity interacts through the AMF entity with the target base station to establish uplink and downlink tunnels between the target base station and the target I-UPF entity. The specific implementation method can refer to the description in the existing protocol, and will not be elaborated in the embodiments of the present application.

[0353] S912: When the forwarding tunnel release timer expires, the A-SMF entity notifies the source UPF entity to release the forwarding tunnel; the target I-SMF entity notifies the target I-UPF entity to release the forwarding tunnel.

[0354] Based on the same inventive concept as the method embodiment, the embodiments of the present application further provide a device for executing the method performed by the target I-SMF entity in any of the above embodiments. The related features can be seen in the above method embodiments and will not be elaborated here. As Figure 10 shown, the device includes a processing unit 1001 and a transceiver unit 1002;

[0355] Specifically, the processing unit 1001 is configured to obtain information of the source session management network element.

[0356] The transceiver unit 1002 is configured to send a first message to the source session management network element according to the information of the source session management network element.

[0357] Among them, the source session management network element is a session management network element that controls the user plane network element interfacing with the source base station; the first message is used to establish a forwarding tunnel from the source intermediate user plane network element to the target intermediate user plane network element. The source intermediate user plane network element is a user plane network element controlled by the source session management network element and interfacing with the source base station, and the target intermediate user plane network element is a user plane network element controlled by the target intermediate session management network element and interfacing with the target base station.

[0358] Before the transceiver unit 1002 sends the first message to the source session management network element according to the information of the source session management network element, it may also obtain first indication information, where the first indication information is used to instruct the target intermediate session management network element to create the forwarding tunnel.

[0359] Specifically, the transceiver unit 1002 may obtain the first indication information in the following two ways:

[0360] Way 1: The transceiver unit 1002 obtains the first indication information from the source session management network element.

[0361] Way 2: The transceiver unit 1002 obtains the first indication information from the mobility management network element.

[0362] After obtaining the first indication information, the processing unit 1001 instructs the target intermediate user plane network element to create the forwarding tunnel according to the first indication information.

[0363] Optionally, the first message includes the forwarding tunnel information corresponding to the target intermediate user plane network element.

[0364] When the processing unit 1001 obtains the information of the source session management network element, it may obtain the information of the source session management network element from the mobility management network element.

[0365] In a possible implementation manner, the processing unit 1001 may also set a forwarding tunnel release timer; when the forwarding tunnel release timer expires, it notifies the intermediate user plane network element to release the forwarding tunnel.

[0366] In a possible implementation manner, the device may also create a tunnel between the target intermediate user plane network element and the anchor user plane network element.

[0367] Specifically, the transceiver unit 1002 obtains session information from the source session management network element according to the information of the source session management network element; or receives the session information from the mobility management network element;

[0368] The processing unit 1001 creates a tunnel between the target intermediate user plane network element and the anchor user plane network element based on the session information.

[0369] Wherein, the session information includes at least one of the following: uplink tunnel information of the anchor user plane network element, information of the anchor session management network element; the anchor session management network element is a session management network element that controls the session between anchor user plane network elements.

[0370] Based on the same inventive concept as the method embodiment, an embodiment of the present application further provides a device for executing the method executed by the source SMF entity in any of the above embodiments. For related features, reference may be made to the above method embodiments and will not be elaborated herein. As Figure 11 shown, the device includes a processing unit 1101 and a transceiver unit 1102;

[0371] Specifically, the transceiver unit 1102 receives a first message from the target intermediate session management network element, and the processing unit 1101 notifies the source intermediate user plane network element to create the forwarding tunnel based on the first message.

[0372] Wherein, the first message is used to establish a forwarding tunnel from the source intermediate user plane network element to the target intermediate user plane network element. The source intermediate user plane network element is a user plane network element controlled by the source session management network element and interfacing with the source base station. The target intermediate session management network element is a session management network element that controls the target intermediate user plane network element interfacing with the target base station;

[0373] The device can also be used to send a first indication message;

[0374] Specifically, the processing unit 1101 first determines that the forwarding tunnel needs to be established; then, the transceiver unit 1102 sends the first indication information to the target intermediate session management network element or the mobility management network element. The first indication information is used to instruct the target intermediate session management network element to create the forwarding tunnel.

[0375] In a possible implementation manner, the processing unit 1101 determines that the forwarding tunnel needs to be established when there is downlink data to be sent to the terminal device in the source session management network element or the source intermediate user plane network element.

[0376] Optionally, the first message includes the forwarding tunnel information corresponding to the target intermediate user plane network element.

[0377] The processing unit 1101 can set a forwarding tunnel release timer; when the forwarding tunnel release timer expires, it notifies the source intermediate user plane network element to release the forwarding tunnel.

[0378] In a possible implementation, the device may also create a tunnel between the target intermediate user plane network element and the anchor user plane network element.

[0379] Specifically, the transceiver unit 1102 sends session information to the target intermediate session management network element, so that the target intermediate session management network element creates a tunnel between the target intermediate user plane network element and the anchor user plane network element; or

[0380] The transceiver unit 1102 sends session information to the mobility management network element, so that the mobility management network element sends the session information to the target intermediate session management network element.

[0381] Wherein, the session information includes at least one of the following: uplink tunnel information of the anchor user plane network element, information of the anchor session management network element; the anchor session management network element is a session management network element that controls the anchor user plane network element.

[0382] Based on the same inventive concept as the method embodiment, an embodiment of the present application also provides a device for executing the method executed by the AMF entity in any of the above method embodiments. For related features, reference may be made to the above method embodiments and will not be elaborated here. As Figure 12 shown, the device includes a processing unit 1201 and a transceiver unit 1202;

[0383] The processing unit 1201 is configured to obtain information of the target intermediate session management network element;

[0384] The transceiver unit 1202 is configured to send information of the source session management network element to the target intermediate session management network element according to the information of the target intermediate session management network element. The source session management network element is a session management network element that controls the user plane network element interfacing with the source base station, and the target intermediate session management network element is a session management network element that controls the target intermediate user plane network element interfacing with the target base station.

[0385] The transceiver unit 1202 may also send first indication information to the target intermediate session management network element, where the first indication information is used to instruct the target intermediate session management network element to create a forwarding tunnel from the source intermediate user plane network element to the target intermediate user plane network element. The source intermediate user plane network element is a user plane network element interfacing with the source base station and controlled by the source session management network element.

[0386] In a possible implementation, before the transceiver unit 1202 sends the first indication information to the target intermediate session management network element, the processing unit 1201 determines that the forwarding tunnel needs to be established;

[0387] In a possible implementation manner, before the transceiver unit 1202 sends the first indication information to the target intermediate session management network element, the transceiver unit 1202 obtains the first indication information from the source session management network element.

[0388] Specifically, if the processing unit 1201 receives a message for triggering a service request process from the source session management network element, the processing unit 1201 determines that a forwarding tunnel needs to be established.

[0389] When the processing unit 1201 obtains information about the target intermediate session management network element, it can be implemented in the following two ways:

[0390] Way 1: The processing unit 1201 obtains the location information of the terminal device and selects the information of the target intermediate session management network element according to the location information of the terminal device;

[0391] Way 2: The processing unit 1201 receives the information of the target intermediate session management network element from the source session management network element.

[0392] In a possible implementation manner, when the device 1200 creates a tunnel between the target intermediate user plane network element and the anchor user plane network element, it can send session information.

[0393] Specifically, the transceiver unit 1202 receives session information from the source session management network element; then, it sends the session information to the target intermediate session management network element so that the target intermediate session management network element creates a tunnel between the target intermediate user plane network element and the anchor user plane network element;

[0394] Among them, the session information includes at least one of the following: uplink tunnel information of the anchor user plane network element, information of the anchor session management network element; the anchor session management network element is the session management network element that controls the anchor user plane network element.

[0395] The division of units in the embodiments of the present application is illustrative. It is only a logical function division. In actual implementation, there may be other division methods. In addition, in each embodiment of the present application, each functional unit can be integrated in one processor, or can exist physically alone, or two or more units can be integrated in one module. The above integrated units can be implemented in the form of hardware or in the form of software function modules.

[0396] When the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a terminal device (which can be a personal computer, mobile phone, or network device, etc.) or a processor to execute all or part of the steps of the method in various embodiments of this application. The aforementioned storage medium includes: various media such as USB flash drives, mobile hard disks, read-only memories (ROMs), random access memories (RAMs), magnetic disks, or optical discs that can store program codes.

[0397] In the embodiments of this application, the target intermediate session management network element (target I-SMF), the source session management network element (source SMF), and the mobility management network element (AMF) can all be presented in the form of dividing each functional module by an integrated method. Here, a "module" can refer to a specific ASIC, circuit, a processor and memory that execute one or more software or firmware programs, an integrated logic circuit, and / or other devices that can provide the above functions. In a simple embodiment, those skilled in the art can think that the target intermediate session management network element (target I-SMF), the source session management network element (source SMF), and the mobility management network element (AMF) can adopt Figure 13 the form shown.

[0398] As Figure 13 shown in the device 1300, it includes at least one processor 131, a memory 132. Optionally, it can also include a communication interface 134.

[0399] The memory 132 can be a volatile memory, such as a random access memory; the memory can also be a non-volatile memory, such as a read-only memory, a flash memory, a hard disk drive (HDD), or a solid-state drive (SSD), or the memory 132 is any other medium that can be used to carry or store the desired program code in the form of instructions or data structures and can be accessed by a computer, but is not limited thereto. The memory 132 can be a combination of the above memories.

[0400] In the embodiments of the present application, the specific connection medium between the above-mentioned processor 131 and the memory 132 is not limited. In the embodiments of the present application, in the figure, the memory 132 and the processor 131 are connected through a bus 133. The bus 133 is represented by a thick line in the figure. The connection manners between other components are only for illustrative purposes and are not limiting. The bus 133 can be divided into an address bus, a data bus, a control bus, etc. For the convenience of representation, Figure 13 only one thick line is used to represent it in the figure, but it does not mean that there is only one bus or one type of bus.

[0401] The processor 131 can have a data transceiver function and be capable of communicating with other devices. In a device such as Figure 13 , an independent data transceiver module can also be provided, such as a communication interface 134, for transceiver data; when the processor 131 communicates with other devices, data transmission can be performed through the communication interface 134.

[0402] When the target intermediate session management network element adopts the Figure 13 form shown, Figure 13 the processor 131 in it can call the computer execution instructions stored in the memory 132, so that the target intermediate session management network element can execute the method executed by the target I-SMF in any of the above method embodiments.

[0403] When the source session management network element adopts the Figure 13 form shown, Figure 13 the processor 131 in it can call the computer execution instructions stored in the memory 132, so that the source session management network element can execute the method executed by the source SMF in any of the above method embodiments.

[0404] When the mobility management network element adopts the Figure 13 form shown, Figure 13 the processor 131 in it can call the computer execution instructions stored in the memory 132, so that the mobility management network element can execute the method executed by the AMF in any of the above method embodiments.

[0405] Specifically, Figures 10 to 12 the functions / implementation processes of the transceiver unit and the processing unit in it can all be realized by the processor 131 in Figure 13 calling the computer execution instructions stored in the memory 132. Or, Figures 10 to 12 the function / implementation process of the processing unit in it can be realized by the processor 131 in Figure 13 calling the computer execution instructions stored in the memory 132, Figures 10 to 12 the function / implementation process of the transceiver unit in it can be realized by the Figure 13 communication interface 134 in it.

[0406] Among them, the processor 131 may include one or more CPUs, such as Figure 13 CPU0 and CPU1 in

[0407] The apparatus 1300 may include multiple processors, such as Figure 13 processor 131 and processor 135 in

[0408] Since the apparatus provided by the embodiments of the present application can execute the above communication method, the technical effects that can be obtained can refer to the above method embodiments and will not be elaborated here.

[0409] In the present application, after the mobility management network element obtains the information of the target intermediate session management network element, it sends the information of the source session management network element to the target session management network element; after the target session management network element obtains the information of the source session management network element, it sends a first message to the source session management network element according to the information of the source session management network element, and the first message is used to establish a forwarding tunnel from the source intermediate user plane network element to the target intermediate user plane network element; after the source session management network element receives the first message from the target intermediate session management network element, based on the first message, it notifies the source intermediate user plane network element to create the forwarding tunnel; through the manner of the embodiments of the present application, a forwarding tunnel from the source intermediate user plane network element to the target intermediate user plane network element is created, so that the source intermediate user plane network element can forward data to the target intermediate user plane network element through the forwarding tunnel, realizing the handover from the target intermediate session management network element to the source session management network element, being able to maintain the session and ensure the service continuity of the terminal device.

[0410] The present application is described with reference to the flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to the present application. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, and the combination of flows and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices generate a device for realizing the functions specified in one or more flows in the flowchart and / or one or more blocks in the block diagram.

[0411] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer-readable memory generate a manufactured article including an instruction device, and the instruction device realizes the functions specified in one or more flows in the flowchart and / or one or more blocks in the block diagram.

[0412] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus, so that a series of operation steps are performed on the computer or other programmable apparatus to produce a computer-implemented process, thereby the instructions executed on the computer or other programmable apparatus provide steps for implementing the functions specified in one process or more processes in the flowchart and / or one block or more blocks in the block diagram.

[0413] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalent technologies, the present application is also intended to include these modifications and variations.

Claims

1. A communication system, characterized in that, The communication system includes a target intermediate session management network element and a source session management network element; The target intermediate session management network element is configured to obtain information of the source session management network element; Send a first message to the source session management network element according to the information of the source session management network element, where the first message is used to establish a forwarding tunnel between a source intermediate user plane network element and a target intermediate user plane network element; The source session management network element is configured to receive the first message from the target intermediate session management network element; Based on the first message, notify the source intermediate user plane network element to create the forwarding tunnel; The source session management network element is further configured to send information of an anchor session management network element to the target intermediate session management network element; the anchor session management network element is a session management network element that controls an anchor user plane network element; The target intermediate session management network element is configured to obtain the information of the anchor session management network element from the source session management network element according to the information of the source session management network element; The target intermediate session management network element is configured to send the downlink tunnel information of the target intermediate user plane network element to the anchor session management network element according to the information of the anchor session management network element, where the downlink tunnel information of the target intermediate user plane network element is used to create a downlink tunnel between the target intermediate user plane network element and the anchor user plane network element; The source intermediate user plane network element is controlled by the source session management network element and interfaces with a source base station, and the target intermediate user plane network element is controlled by the target intermediate session management network element and interfaces with a target base station.

2. The system according to claim 1, wherein The source session management network element is further configured to: determine that it is necessary to establish the forwarding tunnel; send first indication information to the target intermediate session management network element, where the first indication information is used to instruct the target intermediate session management network element to create the forwarding tunnel.

3. The system according to claim 1, wherein The communication system further includes a mobility management network element; The mobility management network element is configured to: determine that it is necessary to establish the forwarding tunnel; send first indication information to the target intermediate session management network element, where the first indication information is used to instruct the target intermediate session management network element to create the forwarding tunnel.

4. The system according to claim 2 or 3, wherein The target intermediate session management network element is further configured to: instruct the target intermediate user plane network element to create the forwarding tunnel according to the first indication information.

5. The system according to any one of claims 1-3, characterized in that, The first message includes forwarding tunnel information corresponding to the target intermediate user plane network element.

6. A communication method, characterized in that, The method includes: The target intermediate session management network element obtains information of the source session management network element; The target intermediate session management network element sends a first message to the source session management network element according to the information of the source session management network element, where the first message is used to establish a forwarding tunnel between a source intermediate user plane network element and a target intermediate user plane network element, the source intermediate user plane network element is controlled by the source session management network element and interfaces with a source base station, and the target intermediate user plane network element is controlled by the target intermediate session management network element and interfaces with a target base station; The target intermediate session management network element obtains the information of the anchor session management network element from the source session management network element according to the information of the source session management network element; the anchor session management network element is the session management network element that controls the anchor user plane network element; The target intermediate session management network element sends the downlink tunnel information of the target intermediate user plane network element to the anchor session management network element according to the information of the anchor session management network element, and the downlink tunnel information of the target intermediate user plane network element is used to create a downlink tunnel between the target intermediate user plane network element and the anchor user plane network element.

7. The method according to claim 6, before the target intermediate session management network element sends a first message to the source session management network element according to the information of the source session management network element, further comprising: The target intermediate session management network element obtains first indication information, and the first indication information is used to instruct the target intermediate session management network element to create the forwarding tunnel.

8. The method according to claim 7, wherein The target intermediate session management network element obtaining the first indication information includes: The target intermediate session management network element obtains the first indication information from the source session management network element; or The target intermediate session management network element obtains the first indication information from the mobility management network element.

9. The method according to claim 6 or 7, after the target intermediate session management network element obtains the first indication information, further comprising: The target intermediate session management network element instructs the target intermediate user plane network element to create the forwarding tunnel according to the first indication information.

10. The method according to any one of claims 6-8, characterized in that, The first message includes the forwarding tunnel information corresponding to the target intermediate user plane network element.

11. The method according to any one of claims 6-8, the target intermediate session management network element obtaining the information of the source session management network element includes: The target intermediate session management network element obtains the information of the source session management network element from the mobility management network element.

12. The method according to any one of claims 6-8, characterized in that, The method further comprises: The target intermediate session management network element sets a forwarding tunnel release timer; When the forwarding tunnel release timer expires, the target intermediate session management network element notifies the intermediate user plane network element to release the forwarding tunnel.

13. The method according to any one of claims 6-8, characterized in that, The source session management network element is the session management network element that controls the user plane network element interfacing with the source base station.

14. The method according to claim 6, wherein The method further comprises: The source session management network element receives the first message from the target intermediate session management network element; based on the first message, notifies the source intermediate user plane network element to create the forwarding tunnel; The source session management network element sends the information of the anchor session management network element to the target intermediate session management network element.

15. A communication method, characterized in that, The method includes: The source session management network element receives a first message from the target intermediate session management network element, and the first message is used to establish a forwarding tunnel between the source intermediate user plane network element and the target intermediate user plane network element. The source intermediate user plane network element is controlled by the source session management network element and interfaces with the source base station, and the target intermediate session management network element controls the target intermediate user plane network element interfacing with the target base station; The source session management network element notifies the source intermediate user plane network element to create the forwarding tunnel based on the first message; The source session management network element sends information of the anchor session management network element to the target intermediate session management network element, so that the target intermediate session management network element sends the downlink tunnel information of the target intermediate user plane network element to the anchor session management network element. The downlink tunnel information of the target intermediate user plane network element is used to create a downlink tunnel between the target intermediate user plane network element and the anchor user plane network element. The anchor session management network element is a session management network element that controls the anchor user plane network element.

16. The method according to claim 15, wherein Before the source session management network element receives the first message from the target intermediate session management network element, it further includes: The source session management network element determines that a forwarding tunnel needs to be established. The source session management network element sends first indication information to the target intermediate session management network element or the mobility management network element. The first indication information is used to instruct the target intermediate session management network element to create the forwarding tunnel.

17. The method according to claim 16, wherein The source session management network element determines that a forwarding tunnel needs to be established, including: When there is downlink data to be sent to the terminal device in the source session management network element or the source intermediate user plane network element, the source session management network element determines that a forwarding tunnel needs to be established.

18. The method according to any one of claims 15-17, characterized in that The first message includes the forwarding tunnel information corresponding to the target intermediate user plane network element.

19. The method according to any one of claims 15-17, characterized in that, The method further includes: The source session management network element sets a forwarding tunnel release timer. When the forwarding tunnel release timer expires, the source session management network element notifies the source intermediate user plane network element to release the forwarding tunnel.

20. A device, characterized in that, The device includes a processing unit and a transceiver unit; The processing unit is used to obtain information of the source session management network element; The transceiver unit is used to send a first message to the source session management network element according to the information of the source session management network element. The first message is used to establish a forwarding tunnel between the source intermediate user plane network element and the target intermediate user plane network element. The source intermediate user plane network element is controlled by the source session management network element and interfaces with the source base station. The target intermediate user plane network element is controlled by the target intermediate session management network element and interfaces with the target base station; The transceiver unit is used to obtain information of the anchor session management network element from the source session management network element according to the information of the source session management network element. The anchor session management network element is a session management network element that controls the anchor user plane network element; The transceiver unit is used to send the downlink tunnel information of the target intermediate user plane network element to the anchor session management network element according to the information of the anchor session management network element. The downlink tunnel information of the target intermediate user plane network element is used to create a downlink tunnel between the target intermediate user plane network element and the anchor user plane network element.

21. The device according to claim 20, wherein the transceiver unit is further used for: Obtaining first indication information, where the first indication information is used to instruct the target intermediate session management network element to create the forwarding tunnel.

22. The device according to claim 21, wherein the transceiver unit is further used for: Obtaining the first indication information from the source session management network element; or Obtaining the first indication information from the mobility management network element.

23. The device according to claim 21 or 22, after obtaining the first indication information, the processing unit is further configured to: According to the first indication information, instruct the target intermediate user plane network element to create the forwarding tunnel.

24. The device according to any one of claims 20-22, characterized in that, The first message includes the forwarding tunnel information corresponding to the target intermediate user plane network element.

25. The device according to any one of claims 20-22, characterized in that, The transceiver unit is further configured to: Obtain information of the source session management network element from the mobility management network element.

26. The device according to any one of claims 20-22, characterized in that, The processing unit is further configured to: Set a forwarding tunnel release timer; In the case where the forwarding tunnel release timer expires, notify the intermediate user plane network element to release the forwarding tunnel.

27. The device according to any one of claims 20-22, characterized in that, The source session management network element is a session management network element that controls the user plane network element of the interface with the source base station.

28. A device, characterized in that, The device includes a processing unit and a transceiver unit; The transceiver unit is configured to receive a first message from the target intermediate session management network element, where the first message is used to establish a forwarding tunnel between the source intermediate user plane network element and the target intermediate user plane network element, the source intermediate user plane network element is controlled by the source session management network element and interfaces with the source base station, and the target intermediate session management network element controls the target intermediate user plane network element that interfaces with the target base station; The processing unit is configured to, based on the first message, notify the source intermediate user plane network element to create the forwarding tunnel; The transceiver unit is configured to send information of the anchor point session management network element to the target intermediate session management network element, so that the target intermediate session management network element sends the downlink tunnel information of the target intermediate user plane network element to the anchor point session management network element, and the downlink tunnel information of the target intermediate user plane network element is used to create a downlink tunnel between the target intermediate user plane network element and the anchor point user plane network element; the anchor point session management network element is a session management network element that controls the anchor point user plane network element.

29. The device according to claim 28, wherein, Before the transceiver unit receives the first message from the target intermediate session management network element, the processing unit is further configured to determine that it is necessary to establish the forwarding tunnel; The transceiver unit is further configured to send first indication information to the target intermediate session management network element or the mobility management network element, where the first indication information is used to instruct the target intermediate session management network element to create the forwarding tunnel.

30. The device according to claim 29, wherein When the processing unit is used to determine that it is necessary to establish the forwarding tunnel, it specifically includes: In the case where there is downlink data to be sent to the terminal device in the source session management network element or the source intermediate user plane network element, determine that it is necessary to establish the forwarding tunnel.

31. The device according to any one of claims 28-30, characterized in that, The processing unit is further configured to: Set a forwarding tunnel release timer; In the case where the forwarding tunnel release timer expires, notify the source intermediate user plane network element to release the forwarding tunnel.

32. A device, characterized in that, The device includes a processor and a memory, the memory stores a computer program; the processor is configured to call and execute the computer program stored in the memory to execute the communication method according to any one of claims 6-13, or the communication method according to any one of claims 15-19.

33. A computer-readable storage medium, characterized in that, Instructions are stored in the computer-readable storage medium, and when it runs on a computer, it enables the computer to execute the communication method described in any one of claims 6-13 or any one of claims 15-19.

34. A computer program product, characterized in that, Instructions are stored in the computer program product, and when it runs on a computer, it enables the computer to execute the communication method described in any one of claims 6-13 or any one of claims 15-19.

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