Communication method and related apparatus

Abstract

The present application provides a communication method and a related apparatus, being conducive to reducing the impact of path switching on the data transmission performance of a terminal. The method comprises: a terminal receives ninth indication information, wherein the ninth indication information is used for indicating that a first session of the terminal has a transmission agent function or the first session supports path switching; the terminal sends fifth instruction information on the basis of the ninth indication information, wherein the fifth instruction information is used for instructing to switch a path for the first session of the terminal; when it is determined that the transmission agent function is provided for the first session, an SMF sends first instruction information to an UPF on the basis of the fifth instruction information, wherein the first instruction information is used for instructing to stop downlink data transmission of the first session; on the basis of the first instruction information, the UPF stops sending downlink data of the first session to a first RAN node.

Description

Communication method and related device

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on January 16, 2024, with application number 202410060856.1 and application name “Communication Methods and Related Devices”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of communications, and in particular to a communication method and related devices. Background Art

[0003] The service data of the terminal's protocol data unit (PDU) session can be transmitted on the transmission control protocol (TCP) connection between the terminal and the server. The user plane function (UPF) on the network side has a routing function and can forward the uplink and downlink data between the terminal and the server.

[0004] In one possible scenario, due to terminal mobility, the terminal's PDU session undergoes path switching between different radio access network (RAN) nodes. For example, the terminal first accesses RAN node 1 and transmits the service data of the PDU session through RAN node 1. After the terminal accesses RAN node 2, the terminal switches the PDU session from RAN node 1 to RAN node 2, and transmits the service data of the PDU session through RAN node 2.

[0005] During this path switching process, if the terminal's capabilities are limited (for example, the terminal cannot continue to communicate with RAN node 1 after connecting to RAN node 2), the server will continue to send the terminal's downlink data to the UPF from the time the terminal connects to RAN node 2 until the terminal's path switching process is completed, and the UPF will continue to forward this downlink data to RAN node 1. However, after the terminal connects to RAN node 2, the communication connection between the terminal and RAN node 1 is interrupted. The terminal cannot receive the downlink data forwarded by the UPF from RAN node 1, and the UPF cannot receive the terminal's acknowledgment (ACK) feedback for this downlink data. The UPF will mistakenly believe that network congestion has occurred, and will then reduce the data transmission rate to alleviate the network congestion, which will affect communication performance.

[0006] Based on this, there is an urgent need to provide a communication method to reduce the impact of path switching on the data transmission performance of the terminal. Summary of the Invention

[0007] The present application provides a communication method and related devices, which are conducive to reducing the impact of path switching on the data transmission performance of a terminal.

[0008] In the first aspect, a communication method is provided, which can be executed by a first communication device. The first communication device can be a UPF, or a component configured in the UPF (such as a processor, chip, or chip system, etc.), or a logic module or software that can realize all or part of the functions of the first communication device. This application does not limit this.

[0009] The method includes: receiving first indication information from a session management function (SMF), the first indication information being used to instruct to stop downlink data transmission of a first session of a terminal; and based on the first indication information, stopping sending downlink data of the first session to a first RAN node, where the first RAN node is a RAN node used to transmit data of the first session before a path switch of the first session.

[0010] In this application, the terminal transmits data of the first session with the UPF through the first RAN node before the path switch. If the terminal is a capability-limited terminal that cannot connect to multiple RAN nodes simultaneously, such as the first RAN node and the second RAN node, then after the terminal connects to the second RAN node, the terminal no longer supports data transmission with the first RAN node.

[0011] Based on the technical solution of this application, the UPF provides a transport proxy function for the first session. In other words, the UPF acts as a transport proxy to forward data between the terminal and the server. Based on instructions from the SMF, the UPF temporarily stops sending downlink data for the first session to the first RAN node. In other words, it temporarily stops sending downlink data for the first session to the terminal via the first RAN node. This eliminates the need for the UPF to attempt to reduce the data transmission rate to send downlink data to the terminal, thus avoiding the loss of downlink data for the first session. This helps reduce the impact of path switching on the terminal's data transmission performance.

[0012] In combination with the first aspect, in some implementations of the first aspect, the method further includes: receiving second indication information from the SMF, the second indication information being used to indicate providing a transport agent function for the first session, the transport agent being a TCP connection transport agent, or the transport agent being a quick user datagram protocol internet connection (QUIC) transport agent; and based on the second indication information, providing the transport agent function for the first session.

[0013] In combination with the first aspect, in some implementations of the first aspect, stopping sending downlink data of the first session to the first RAN node includes: stopping sending downlink data of the first session to the first RAN node through the first communication connection, where the first communication connection is a TCP connection or a QUIC connection between the terminal and the UPF.

[0014] In conjunction with the first aspect, in certain implementations of the first aspect, after stopping sending downlink data of the first session to the first RAN node via the first communication connection, the method further includes: receiving downlink data of the first session transmitted via a second communication connection; and buffering the downlink data of the first session transmitted on the second communication connection. The second communication connection is a TCP connection or a QUIC connection between the UPF and the server.

[0015] In the present application, the UPF temporarily caches the downlink data of the first session, which helps to avoid the loss of the downlink data of the first session and thereby improves the service continuity of the first session.

[0016] In combination with the first aspect, in some implementations of the first aspect, the method further includes: receiving third indication information from the SMF, the third indication information being used to indicate a first duration, where the first duration is a duration for caching downlink data of the first session.

[0017] In conjunction with the first aspect, in certain implementations of the first aspect, after stopping sending downlink data of the first session to the first RAN node via the first communication connection, the method further includes: receiving fourth indication information from the SMF, the fourth indication information being used to instruct the start of downlink data transmission for the first session; and based on the fourth indication information, sending the downlink data of the first session to a second RAN node via the first communication connection in accordance with stored communication connection parameters. The second RAN node is a RAN node used to transmit data of the first session after path switching for the first session. The communication connection parameters are communication connection parameters used when stopping sending downlink data of the first session to the first RAN node via the first communication connection.

[0018] In the present application, the downlink data of the first session is sent according to the stored communication connection parameters, which is beneficial to improving the data transmission efficiency of the UPF.

[0019] On the second aspect, a communication method is provided, which can be executed by a second communication device. The first communication device can be an SMF, or a component configured in the SMF (such as a processor, chip, or chip system, etc.), or a logical module or software that can realize all or part of the functions of the second communication device. This application does not limit this.

[0020] The method includes: receiving fifth indication information, which is used to indicate the switching path for the first session of the terminal; when it is determined that the UPF provides the function of a transmission agent for the first session, based on the fifth indication information, sending first indication information to the UPF, which is used to indicate the stop of downlink data transmission of the first session, and the transmission agent is a TCP connection transmission agent, or the transmission agent is a QUIC transmission agent.

[0021] In this application, under the premise that the UPF provides the function of a transmission agent for the first session, data is transmitted between the terminal and the UPF through the first communication connection, and data is transmitted between the UPF and the server through the second communication connection. Therefore, when the SMF determines that the UPF provides the function of a transmission agent for the first session, it can instruct the UPF to stop the downlink data transmission of the first session to reduce the impact of the path switching on the data transmission performance of the terminal.

[0022] In combination with the second aspect, in certain implementations of the second aspect, the method further includes: sending third indication information to the UPF, where the third indication information is used to indicate a first duration, where the first duration is the duration for caching downlink data of the first session.

[0023] In combination with the second aspect, in certain implementations of the second aspect, the method further includes: receiving sixth indication information, where the sixth indication information is used to indicate that the terminal does not support data transmission with a first RAN node during the path switching of the first session, where the first RAN node is a RAN node used to transmit data of the first session before the path switching of the first session.

[0024] In combination with the second aspect, in certain implementations of the second aspect, sending the first indication information to the UPF based on the fifth indication information includes: sending the first indication information to the UPF based on the fifth indication information and the sixth indication information.

[0025] In combination with the second aspect, in certain implementations of the second aspect, before receiving the fifth indication information, the method also includes: sending second indication information to the UPF, where the second indication information is used to indicate the function of providing the transmission agent for the first session.

[0026] In combination with the second aspect, in certain implementations of the second aspect, sending second indication information to the UPF includes: sending second indication information to the UPF based on the sixth indication information.

[0027] In conjunction with the second aspect, in some implementations of the second aspect, before sending the second indication information to the UPF, the method further includes: receiving seventh indication information, where the seventh indication information is used to indicate that the terminal supports path switching for the first session or the terminal supports path switching. Sending the second indication information to the UPF includes: sending the second indication information to the UPF based on the seventh indication information.

[0028] In conjunction with the second aspect, in some implementations of the second aspect, before sending the second indication information to the UPF, the method further includes: receiving eighth indication information, where the eighth indication information is used to indicate support for service continuity of the first session during path switching. Sending the second indication information to the UPF includes: sending the second indication information to the UPF based on the eighth indication information.

[0029] In combination with the second aspect, in certain implementations of the second aspect, after sending the second indication information to the UPF, the method also includes: sending ninth indication information to the terminal, the ninth indication information being used to indicate that the first session has the function of the transmission agent or that the first session supports path switching.

[0030] In combination with the second aspect, in certain implementations of the second aspect, after sending the first indication information to the UPF, the method further includes: sending fourth indication information to the UPF, where the fourth indication information is used to indicate the start of downlink data transmission of the first session.

[0031] On the third aspect, a communication method is provided, which can be executed by a third communication device. The third communication device can be a terminal, or a component configured in the terminal (such as a processor, a chip, or a chip system, etc.), or a logic module or software that can realize all or part of the functions of the second communication device. This application does not limit this. The method includes: receiving ninth indication information, the ninth indication information is used to indicate that the first session of the terminal has the function of a transmission agent or the first session supports path switching, the transmission agent is a transmission control protocol TCP connection transmission agent, or the transmission agent is a fast user datagram protocol network connection QUIC transmission agent; based on the ninth indication information, sending fifth indication information, the fifth indication information is used to indicate the switching path for the first session of the terminal.

[0032] In the present application, after receiving the ninth indication information, the terminal determines that the first session of the terminal has the function of a transmission agent, or in other words, determines that the first session supports path switching, that is, the first session supports service continuity during the path switching, and more specifically, the first session supports no data loss during the path switching. Under this premise, when the terminal sends the fifth indication information to indicate path switching, it is helpful to avoid the loss of downlink data of the first session, thereby helping to reduce the impact of the path switching on the data transmission performance of the terminal.

[0033] In combination with the third aspect, in certain implementations of the third aspect, sending the fifth indication information includes: sending the fifth indication information through a first RAN node, where the first RAN node is a RAN node used to transmit data of the first session before the path switching of the first session.

[0034] In combination with the third aspect, in certain implementations of the third aspect, sending the fifth indication information includes: sending the fifth indication information through a second RAN node, where the second RAN node is a RAN node used to transmit data of the first session after the path switching of the first session.

[0035] In combination with the third aspect, in certain implementations of the third aspect, the method further includes: sending sixth indication information, where the sixth indication information is used to indicate that the terminal does not support data transmission with a first RAN node during the path switching of the first session, and the first RAN node is the RAN node used to transmit data of the first session before the path switching of the first session.

[0036] In combination with the third aspect, in certain implementations of the third aspect, before receiving the ninth indication information, the method further includes: sending seventh indication information, where the seventh indication information is used to indicate that the terminal supports path switching of the first session or the terminal supports path switching.

[0037] It should be understood that the second and third aspects of the present application correspond to the technical solutions of the first aspect of the present application, and the beneficial effects achieved by each aspect and the corresponding feasible implementation methods are similar and will not be repeated here.

[0038] In a fourth aspect, a communication device is provided, comprising: a module for executing the method in any possible implementation of any of the above aspects. Specifically, the device comprises a module for executing the method in any possible implementation of any of the above aspects.

[0039] In one design, the device may include a module corresponding to each of the methods / operations / steps / actions described in any of the above aspects. The module may be a hardware circuit, software, or a combination of hardware circuit and software.

[0040] In another design, the device is a communication chip, which may include an input circuit or interface for sending information or data, and an output circuit or interface for receiving information or data.

[0041] In another design, the device is a UPF, SMF or terminal, and the UPF, SMF or terminal may include a transmitter for sending information or data and a receiver for receiving information or data.

[0042] In another design, the device is used to execute the method in any possible implementation of any of the above aspects, and the device can be configured in a UPF, SMF or terminal.

[0043] In a fifth aspect, a communication device is provided, comprising a processor configured to call and run a computer program from a memory, so that the device executes a method in any possible implementation of any of the above aspects.

[0044] Optionally, the device further comprises a memory, which can be used to store instructions and data. The memory is coupled to the processor, and when the processor executes the instructions stored in the memory, the method described in the above aspects can be implemented.

[0045] Optionally, the device further includes: a transmitter (emitter) and a receiver (receiver), and the transmitter and the receiver can be separately provided or integrated together, and are referred to as a transceiver (transceiver).

[0046] In a sixth aspect, a computer program product is provided, comprising: a computer program (also referred to as code, or instructions), which, when executed, enables a computer to execute a method in any possible implementation of any of the above aspects.

[0047] In the seventh aspect, a computer-readable storage medium is provided, which stores a computer program (also referred to as code, or instructions) which, when run on a computer, enables the computer to execute a method in any possible implementation of any of the above aspects.

[0048] In an eighth aspect, the present application provides a chip system comprising at least one processor for supporting the implementation of the functions involved in any of the above aspects, such as receiving or processing the data involved in the above method.

[0049] In one possible design, the chip system further includes a memory, which is used to store program instructions and data, and the memory is located inside or outside the processor.

[0050] Optionally, the chip system may consist of a chip, or may include a chip and other discrete devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] FIG1 is a schematic diagram of TCP congestion control;

[0052] FIG2 is a schematic diagram of a bidirectional TCP proxy;

[0053] FIG3 is a schematic diagram of a path switching of a PDU session between different RAN nodes;

[0054] FIG4 is a schematic diagram of the architecture of a communication system applicable to an embodiment of the present application;

[0055] 5 to 9 are schematic flow charts of the communication method provided in the embodiments of the present application;

[0056] 10 and 11 are schematic block diagrams of a communication device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0057] The technical solution in this application will be described below with reference to the accompanying drawings.

[0058] Before introducing the communication method and related devices provided in the embodiments of the present application, the following points are explained.

[0059] First, in the embodiments described below, various terms and abbreviations, such as TCP, PDU, and transport agent, are provided for ease of description and should not limit this application in any way. This application does not exclude the possibility of defining other terms in existing or future protocols that can achieve the same or similar functions.

[0060] Second, the first, second and various numerical numbers in the embodiments shown below are only used for the convenience of description and are not intended to limit the scope of the embodiments of the present application.

[0061] Third, "at least one" means one or more, and "more" means two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone, where A and B can be singular or plural. The character " / " generally indicates that the previous and next associated objects are in an "or" relationship. "At least one of the following items" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, at least one of a, b and c can mean: a, or b, or c, or a and b, or a and c, or b and c, or a, b and c, where a, b, c can be single or multiple.

[0062] Fourth, the terms "sending" and "receiving" in this application refer to the direction of signal transmission. For example, "sending third indication information to UPF" can be understood as the destination of the third indication information being the UPF, which can include direct sending through the air interface, as well as indirect sending through the air interface by other units or modules. "Receiving first indication information from SMF" can be understood as the source of the first indication information being the SMF, which can include direct receiving from the SMF through the air interface, as well as indirect receiving from the SMF through the air interface from other units or modules. "Sending" can also be understood as the "output" of the chip interface, and "receiving" can also be understood as the "input" of the chip interface.

[0063] In other words, sending and receiving can be performed between devices, for example, between SMF and UPF; it can also be performed within a device, for example, sending or receiving between components, modules, chips, software modules or hardware modules within the device through a bus, trace or interface.

[0064] The following is an introduction to the relevant technologies and concepts involved in this application.

[0065] 1. TCP congestion control

[0066] Figure 1 is a schematic diagram of TCP congestion control. As shown in Figure 1, the main mechanisms of TCP congestion control include:

[0067] (1) Slow start: When a TCP connection is established, the sender first sends a small amount of data at a low data transmission rate, and then gradually increases the data transmission rate until the network becomes congested.

[0068] (2) Congestion avoidance: When network congestion occurs, TCP will reduce the data transmission rate to avoid further congestion. Congestion avoidance mechanisms include congestion window and congestion avoidance algorithm.

[0069] (3) Fast retransmission: When the receiver detects packet loss, it repeatedly sends ACKs to the sender to indicate an abnormality. After receiving three consecutive ACKs, the sender considers the packet to be discarded and triggers a retransmission.

[0070] (4) Rapid recovery: When light congestion and packet loss occur, the data transmission rate is rapidly reduced until the network congestion is eliminated. If the data transmission rate is reduced by half each time a congestion and packet loss is detected, the congestion window can be reduced exponentially. When severe congestion (send timeout) occurs, the system reverts to the initial state.

[0071] 2. Transport Agent

[0072] The transport agents involved in this application include TCP transport agents and QUIC transport agents.

[0073] In a connection with a TCP proxy, the proxy server establishes a TCP connection with the client, and the proxy client establishes another TCP connection with the server. That is, the client and server complete data exchange through these two TCP connections.

[0074] In the bidirectional TCP proxy mode shown in Figure 2, the TCP client establishes a TCP connection with the TCP proxy, and the TCP proxy establishes another TCP connection with the TCP server. These two TCP connections use different sequence numbers. Therefore, during the TCP message exchange process, after receiving the message sent by the sender, the TCP proxy needs to modify the message sequence number before forwarding it to the receiver to ensure normal communication between the client and server.

[0075] Similar to the above-mentioned TCP proxy, in the bidirectional QUIC proxy mode, the QUIC client establishes a QUIC connection with the QUIC proxy, and the QUIC proxy establishes another QUIC connection with the QUIC server.

[0076] In this application, when the transport agent is a TCP transport agent, the TCP client corresponds to the terminal, the TCP agent corresponds to the UPF, and the TCP server corresponds to the server or the application function (AF) in the core network.

[0077] In this application, when the transport agent is a QUIC transport agent, the QUIC client corresponds to the terminal, the QUIC agent corresponds to the UPF, and the QUIC server corresponds to the server or AF in the core network.

[0078] 3. Path Switching of PDU Sessions

[0079] Figure 3 is a schematic diagram of a path switch for a PDU session between different RAN nodes, wherein the path switch may also be described as a traffic switch, which is not limited in this application.

[0080] The terminal accesses the first RAN node and sends a PDU session establishment request message to the access and mobility management function (AMF) through the first RAN node. The PDU session establishment request message includes the identifier (ID) and data network name (DNN) of the PDU session. Afterwards, the AMF selects the UPF to allocate an Internet Protocol (IP) address to the terminal so that the terminal can use the IP address to send data. The AMF selects the SMF to configure the N3 interface between the first RAN node and the UPF, and the first RAN node configures the data radio bearer between it and the terminal. The SMF stores the terminal's subscription permanent identifier (SUPI), the SMF's identifier, the PDU session identifier, and the DNN in the unified data management (UDM). Afterwards, the terminal transmits the service data of the PDU session through the first RAN node.

[0081] For example, during the terminal's mobility process, the terminal accesses a second RAN node and sends a PDU session establishment request message to the AMF through RAN node 2. The PDU session establishment request message carries the PDU session identifier and a handover indication. After receiving the PDU session establishment request message, the AMF determines the SMF corresponding to the PDU session from the UDM based on the PDU session identifier. The SMF continues to maintain the IP address of the PDU session unchanged (so that the terminal can continue to use this IP address to send data). The SMF configures the N3 interface between RAN node 2 and the UPF (so that the UPF sends downlink data from the server to RAN node 2 instead of the first RAN node). RAN node 2 configures a data radio bearer between itself and the terminal (so that the terminal sends uplink data to RAN node 2 instead of the first RAN node). Subsequently, the terminal switches the PDU session from the first RAN node to RAN node 2 and transmits the service data of the PDU session through RAN node 2.

[0082] During the path switching process of the above-mentioned PDU session between different RAN nodes, a TCP connection is established between the UE and the server, and the UPF forwards the service data of the PDU session based on the IP address on the TCP connection.

[0083] Referring to Figure 3 above, in the case of limited terminal capabilities, that is, after the terminal connects to RAN node 2, the terminal does not support data transmission with the first RAN node. From the time the terminal connects to RAN node 2 until the path switch of the terminal's PDU session occurs, the server sends the terminal's downlink data to the UPF, and the UPF continues to send the terminal's downlink data to the first RAN node. However, after the terminal connects to RAN node 2, the communication connection between the terminal and the first RAN node is interrupted. The terminal cannot receive the downlink data forwarded by the UPF from the first RAN node, and the UPF cannot receive the terminal's ACK feedback for the downlink data. As a result, the UPF mistakenly believes that network congestion has occurred and reduces the data transmission rate to alleviate the network congestion, which affects communication performance.

[0084] In view of this, the present application provides a communication method that, when performing a path switch for a first session of a terminal, can temporarily stop the UPF from sending downlink data to the terminal because the communication connection between the terminal and the UPF has been interrupted. This can avoid the loss of downlink data and thus help improve communication performance.

[0085] Figure 4 is a schematic diagram of the architecture of a communication system applicable to an embodiment of the present application. Figure 4 takes the 5th generation mobile communication technology (5G) system architecture as an example, and the network functions and entities (also referred to as network elements) shown include: user equipment (UE), RAN, UPF, data network (DN), AMF, SMF, AF, UDM, network exposure function (NEF), policy control function (PCF), network repository function (NRF), network slice selection function (NSSF), authentication server function (AUSF). Optionally, the system architecture also includes a network data analytics function (NWDAF).

[0086] The UE, RAN, UPF, and DN in Figure 4 are generally referred to as data plane network functions and entities. User data traffic can be transmitted through the PDU session established between the UE and DN, passing through the RAN node and the UPF. Other network elements are called control plane network functions and entities, and are primarily responsible for functions such as authentication and authorization, registration management, session management (SM), mobility management, and policy control, thereby ensuring reliable and stable transmission of user-layer traffic. The user plane carries service data, and the control plane carries signaling messages.

[0087] Figure 4 shows the interaction between network functions and entities and the corresponding interfaces. For example, the UE and AMF can interact through the N1 interface, and the interaction messages are called N1 messages. Some interfaces are implemented as service-oriented interfaces.

[0088] The AMF is a network element, module, or component that provides access management functions. It is primarily responsible for signaling processing, such as access control, mobility management, attach and detach, and gateway selection. When the AMF network element provides services for a session in a terminal, it provides control plane storage resources for the session to store the session identifier and the identifier of the SMF network element associated with the session identifier.

[0089] The SMF is a network element, module or component responsible for processing user services, such as user plane function selection, user plane function redirection, IP address allocation, bearer establishment, modification and release, and quality of service (QoS) control.

[0090] The UPF is responsible for forwarding and receiving user data within the terminal. The UPF can receive user data from the DN and transmit it to the UE via the RAN node. The UPF network element can also receive user data from the UE via the RAN node and forward it to the DN. The transmission resources and scheduling functions provided by the UPF network element to the UE are managed and controlled by the SMF network element.

[0091] NEF mainly supports the secure interaction between the 3rd Generation Partnership Project (3GPP) network and third-party applications.

[0092] AF mainly supports interaction with the 3GPP core network to provide services, such as data routing decisions, policy control functions, or providing some third-party services to the network side.

[0093] The PCF is responsible for policy control decisions, providing policy rules for control plane functions, and flow-based charging control functions.

[0094] NSSF is mainly responsible for network slice selection and determines the network slice instance that the UE is allowed to access based on the UE's slice selection auxiliary information, subscription information, etc.

[0095] UDM is mainly responsible for UE subscription data management, including storage and management of UE identification, UE access authorization, etc.

[0096] AUSF supports 3GPP and non-3GPP access authentication.

[0097] NRF supports registration and discovery of network functions.

[0098] The UDR is responsible for storing and retrieving the contract data used by the UDM and PCF.

[0099] NWDAF supports data collection from other network functions and AF, supports data collection from operations, administration and maintenance (OAM), and supports providing analysis information to other network functions and AF.

[0100] The RAN node provided in the embodiment of the present application can be a base station, a Node B, an evolved Node B (eNodeB or eNB), a transmission reception point (TRP), a next generation Node B (gNB) in 5G or NR, a RAN node in an open radio access network (O-RAN or open RAN), or a next generation base station in the sixth generation mobile communication technology (6G). Alternatively, the RAN node can also be a satellite base station in a non-terrestrial network (NTN) communication network, or a base station in a future mobile communication system, or an access node in a wireless fidelity (Wi-Fi) system. Alternatively, the RAN node can also be a module or unit that performs part of the functions of a base station, for example, a centralized unit (CU) or a distributed unit (DU). The functions of the CU can be implemented by one entity or by different entities. For example, the functions of the CU can be further divided, for example, the control plane (CP) and the user plane (UP) can be separated, that is, the control plane of the CU (CU-CP) and the user plane of the CU (CU-UP). The RAN node can be a macro base station, a micro base station, an indoor station, a relay node, or a donor node. The specific technology and specific device form used by the RAN node are not limited in this application.

[0101] The terminal provided in the embodiments of the present application may also be referred to as a terminal device, user equipment, mobile station, or mobile terminal. The terminal can be widely used in various scenarios for communication. Such scenarios include, but are not limited to, at least one of the following: enhanced mobile broadband (eMBB), ultra-reliable low-latency communication (URLLC), massive machine-type communications (mMTC), device-to-device (D2D), vehicle-to-everything (V2X), machine-type communication (MTC), Internet of Things (IoT), virtual reality, augmented reality, industrial control, autonomous driving, telemedicine, smart grid, smart furniture, smart office, smart wearable, smart transportation, or smart city. The terminal can be a mobile phone, tablet computer, computer with wireless transceiver capabilities, wearable device, vehicle, helicopter, airplane, drone, ship, robot, robotic arm, or smart home device. This application does not limit the specific technology and device form factor used by the terminal device.

[0102] The above-mentioned network elements can be fixed or movable. The above-mentioned network elements can be deployed on land, including indoors or outdoors, handheld or vehicle-mounted; or can be deployed on the water surface; or can be deployed on airplanes, balloons and artificial satellites in the air. This application does not limit the environment / scenario in which the above-mentioned network elements are located. The above-mentioned network elements can be deployed in the same or different environments / scenarios, for example, the UE and RAN nodes are deployed on land at the same time; or, the UE is deployed on land and the RAN node is deployed on the water surface, etc., and examples are not given one by one here. This application does not limit the communication method between the above-mentioned multiple network elements.

[0103] In an embodiment of the present application, the network element shown in Figure 4 can be a hardware device, or it can be a software function running on dedicated hardware, a software function running on general-purpose hardware, such as a virtualization function instantiated on a platform (for example, a cloud platform), or an entity including dedicated or general-purpose hardware devices and software functions. This application does not limit the specific form of each network element.

[0104] Figure 5 is a schematic flow chart of a communication method 500 provided in an embodiment of the present application. Method 500 is applicable to the communication system shown in Figure 4 above and is implemented by the interaction of multiple network elements shown in Figure 4. The AMF in Figure 5 is the first AMF or the second AMF, where the first AMF is the AMF accessed by the terminal through the first RAN node, and the second AMF is the AMF accessed by the terminal through the second RAN node.

[0105] The method 500 includes S501 to S510, and the specific steps are as follows:

[0106] S501: The SMF sends ninth indication information to a terminal, where the ninth indication information is used to indicate that a first session of the terminal has a transmission agent function or supports path switching. Accordingly, the terminal receives the ninth indication information.

[0107] In this step, the transport agent is a TCP connection transport agent or a QUIC transport agent.

[0108] The first session is a PDU session, a computing session, or a data transmission session.

[0109] The first session of the terminal has the function of a transmission agent, which can also be described as the first session of the terminal has the attributes of a transmission agent, or can also be described as the first session of the terminal provides the function of a transmission agent, or can also be described as the UPF of the first session of the terminal provides the function of a transmission agent.

[0110] The first session supports path switching, which can be understood as supporting terminal-triggered path switching. Alternatively, the first session supports path switching, which can be understood as supporting service continuity during path switching. That is, during the path switching of the first session, data of the first session will not be lost, and the IP address used to transmit data of the first session will not change.

[0111] After the first session is established, the UPF enables the transmission agent function, establishes a first communication connection between the terminal and the UPF, and establishes a second communication connection between the UPF and the server. The first communication connection and the second communication connection are used to transmit data between the terminal and the server. Specifically, the UPF, as a transmission agent, transmits the data of the first session with the terminal via the first communication connection, and the UPF, as a transmission agent, transmits the data of the first session with the server via the second communication connection.

[0112] The communication connection in the embodiments of the present application is a TCP connection or a QUIC connection. That is, the first communication connection is a TCP connection between the terminal and the UPF, referred to as the first TCP connection, and the second communication connection is a TCP connection between the UPF and the server, referred to as the second TCP connection. Alternatively, the first communication connection is a QUIC connection between the terminal and the UPF, referred to as the first QUIC connection, and the second communication connection is a QUIC connection between the UPF and the server, referred to as the second QUIC connection.

[0113] Optionally, S501 includes: the SMF sends ninth indication information to the terminal through the first RAN node.

[0114] Optionally, the SMF receives a session establishment request message sent by the terminal, and the SMF sends a session establishment reception message to the terminal, where the session establishment reception message includes the ninth indication information.

[0115] After receiving the ninth indication information, the terminal stores the ninth indication information for the first session. In this way, the terminal can subsequently initiate a path switching process for the first session according to the ninth indication information, see S502.

[0116] The data of the first session is transmitted via a user plane path. For an established first session, its user plane path is variable. Terminal movement or policy changes may cause the terminal or SMF to switch the user plane path of the first session. The switching path in this application is the user plane path for switching the first session.

[0117] S502: The terminal sends fifth indication information to the SMF, where the fifth indication information is used to indicate switching a path for the first session of the terminal. Correspondingly, the SMF receives the fifth indication information.

[0118] In one possible scenario, the connection management (CM) state between the terminal and the AMF is CM-Connected. The CM-Connected state means that the terminal has a signaling connection with the AMF. When a terminal in the CM-Connected state moves from the network coverage of a first RAN node to the network coverage of a second RAN node, a path switching process for the first session can be triggered.

[0119] S502 includes: the terminal sending fifth indication information based on the ninth indication information. That is, when the terminal determines that the first session has the transmission agent function or the first session supports path switching, the terminal can send the fifth indication information to trigger the path switching process of the embodiment of the present application that supports service continuity of the first session during the path switching.

[0120] In the case of a terminal with limited capabilities, once the terminal moves into the network coverage area of ​​a second RAN node and connects to the second RAN node, the terminal no longer supports data transmission with the first RAN node. After connecting to the second RAN node, a terminal with limited capabilities cannot connect to the first RAN node. In other words, a terminal with limited capabilities cannot connect to both the first and second RAN nodes simultaneously.

[0121] In one possible scenario, the terminal disconnects from the first RAN node and connects to the second RAN node. In this case, the terminal sends fifth indication information to the SMF, including: the terminal sends the fifth indication information to the SMF via the second RAN node. The fifth indication information may be a handover indication or an existing session. For ease of distinction and explanation, this scenario is referred to as scenario 1.

[0122] Optionally, the handover indication or the existing session is carried in a non-access stratum (NAS) message, and the handover indication or the existing session is a request type for establishing a first session. When the request type is the handover indication or the existing session, the indication is associated with the existing session.

[0123] Optionally, the NAS message further includes an identifier of the first session. Based on the identifier of the first session, the first session can be associated and the SMF that manages the first session can be determined.

[0124] It should be noted that, if the terminal does not indicate whether it supports data transmission with the first RAN node during the path switching of the first session, the network side defaults that the terminal does not support data transmission with the first RAN node during the path switching of the first session.

[0125] In combination with the above scenario 1, the terminal sends the fifth indication information to the SMF through the second RAN node, including: the terminal sends the fifth indication information to the second AMF through the second RAN node, and further, the second AMF sends the fifth indication information to the SMF. It can be understood that the terminal transparently transmits the fifth indication information through the second AMF.

[0126] In another possible scenario, the terminal maintains a connection with the first RAN node and sends the fifth indication information to the SMF, including: the terminal sends the fifth indication information to the SMF through the first RAN node. For ease of distinction and explanation, this scenario is referred to as scenario 2.

[0127] In scenario 2, the fifth indication information indicates a path handover for the first session of the terminal. Alternatively, the fifth indication information indicates that a path handover for the first session of the terminal is being prepared. The terminal then triggers a path handover procedure via the second RAN node. For details, see the description of method 900 below and are not detailed here.

[0128] In combination with the above situation 2, the terminal sends the fifth indication information to the SMF through the first RAN node, including: the terminal sends the fifth indication information to the first AMF through the first RAN node, and further, the first AMF sends the fifth indication information to the SMF.

[0129] It should be noted that in this application, data can be transmitted between the terminal and the SMF through the AMF. For example, the terminal sending information to the SMF mentioned below can be understood as: the terminal sends information to the SMF through the RAN node (first RAN node or second RAN node) and the AMF (first AMF or second AMF).

[0130] In this application, data may not be transmitted between the terminal and the SMF through the AMF. For example, the terminal sending information to the SMF in the following text can be understood as: the terminal sends information to the SMF through the RAN node (the first RAN node or the second RAN node).

[0131] Similarly, SMF sending information can be understood as: SMF sending information to the terminal through AMF (first AMF or second AMF) and RAN node (first RAN node or second RAN node).

[0132] The case where the terminal or SMF serves as the receiving end of information is similar to the case where it serves as the sending end of information, and will not be described in detail here.

[0133] S503: When the SMF determines that the UPF provides a transmission agent function for the first session, the SMF sends a first indication message to the UPF based on the fifth indication message, where the first indication message is used to instruct the UPF to stop downlink data transmission of the first session. Accordingly, the UPF receives the first indication message.

[0134] Stopping downlink data transmission of the first session may be described as stopping transmission of downlink data of the first session over the first communication connection.

[0135] The SMF stores information for instructing the UPF to provide a transport proxy function for the first session. Alternatively, the SMF stores information for instructing the UPF to enable the transport proxy function for the first session. After receiving the fifth indication information, the SMF determines that a path switch is required for the first session. Furthermore, based on the stored information, the SMF determines that the UPF should provide the transport proxy function for the first session. Furthermore, the SMF sends the first indication information to the UPF to support service continuity for the first session during the path switch.

[0136] S504: The UPF stops sending downlink data of the first session to the first RAN node based on the first indication information.

[0137] In this step, the UPF stops sending the downlink data of the first session to the first RAN node, which can avoid the loss of the downlink data of the first session and is conducive to reducing the impact of the path switching on the data transmission performance of the terminal.

[0138] In combination with situation 1 in the above S502, the terminal has already disconnected from the first RAN node when receiving the first indication information. The UPF stops sending downlink data of the first session to the first RAN node based on the first indication information, thereby avoiding the subsequent loss of downlink data of the first session and reducing the impact of path switching on the data transmission performance of the terminal.

[0139] In combination with Case 2 in the above S502, the terminal disconnects from the first RAN node after receiving the first indication information. This can avoid the loss of downlink data that the UPF has sent to the terminal during the period from the terminal accessing the second RAN node to the UPF stopping sending downlink data of the first session, thereby helping to better improve the service continuity of the first session and reduce the impact of path switching on the data transmission performance of the terminal.

[0140] Optionally, in S504, the UPF stops sending the downlink data of the first session to the first RAN node, including: the UPF stops sending the downlink data of the first session to the first RAN node through the first communication connection.

[0141] As can be seen from the description above, the first communication connection is the communication connection between the terminal and the UPF. Because the terminal does not support data transmission with the first RAN node during the path switch of the first session, and the path of the first session has not yet been switched to the second RAN node, the UPF can stop sending downlink data of the first session to the first RAN node through the first communication connection.

[0142] The UPF stops sending downlink data of the first session to the first RAN node through the first communication connection. It can also be described as that the UPF stops sending downlink data of the first session to the first RAN node on the first communication connection.

[0143] When the first communication connection between the terminal and the UPF is interrupted, the second communication connection between the UPF and the server is not affected. The UPF can normally receive downlink data from the server through the second communication connection and send ACK feedback to the server. In this way, the server can maintain the current data transmission rate and continue to send the downlink data of the first session to the UPF, which is conducive to improving the communication performance of the first session. The second communication connection is the communication connection between the UPF and the server.

[0144] Optionally, method 500 further includes S505: the SMF sends third indication information to the UPF, where the third indication information is used to indicate a first duration, where the first duration is the duration for caching the downlink data of the first session. After receiving the third indication information, the UPF caches the downlink data of the first session transmitted by the server through the second communication connection according to the first duration. When the duration for caching the downlink data of the first session reaches the first duration, the UPF stops caching.

[0145] Optionally, the SMF may determine the first duration according to a preconfigured duration required for the switching path.

[0146] Optionally, the UPF stores communication connection parameters used when stopping sending downlink data of the first session to the first RAN node through the first communication connection, such as a sending window, a data transmission rate, etc.

[0147] Optionally, method 500 further includes S506: the SMF sends fourth indication information to the UPF, where the fourth indication information is used to indicate the start of downlink data transmission for the first session. Accordingly, the UPF receives the fourth indication information. Furthermore, the UPF sends the downlink data of the first session to the second RAN node via the first communication connection according to the stored communication connection parameters.

[0148] Among them, the fourth indication information can be the access network tunnel information (AN tunnel information) of the second RAN node. After the UPF receives the access network tunnel information of the second RAN node, it means that the path switching of the first session has been completed. The UPF can start sending downlink data of the first session to the second RAN node through the first communication connection according to the access network tunnel information.

[0149] Optionally, after receiving the access network tunnel information, the UPF receives indication information for starting downlink data transmission from the SMF, and the UPF starts sending downlink data of the first session to the second RAN node based on the indication information.

[0150] It should be noted that before the path switching of the first session, the communication connection between the terminal and the UPF is the first communication connection, and data transmission between the terminal and the UPF through the first communication connection passes through the first RAN node. In other words, data transmission between the terminal and the UPF over the first communication connection passes through the first RAN node.

[0151] After the path switch for the first session, the communication connection between the terminal and the UPF remains the first communication connection, but data transmitted between the terminal and the UPF over the first communication connection passes through the second RAN node. In other words, data transmitted between the terminal and the UPF over the first communication connection passes through the second RAN node.

[0152] Optionally, the method 500 further includes S507: the terminal sends sixth indication information, where the sixth indication information is used to indicate that the terminal does not support data transmission with the first RAN node during the path switch of the first session.

[0153] The terminal does not support data transmission with the first RAN node during the path switching of the first session. It can be understood that the terminal does not support data transmission with the source RAN node during the path switching of the first session, and the terminal does not support data transmission on the source path during the path switching of the first session.

[0154] In a possible implementation, the terminal may send the sixth indication information before S502. For example, during the establishment of the first session through the first AMF, the terminal sends the sixth indication information to the SMF through the first AMF.

[0155] In another possible implementation, the terminal may send the fifth indication information and the sixth indication information simultaneously. In this case, S502 and S507 may be combined into one step. The NAS message described in S502 may include the fifth indication information and the sixth indication information.

[0156] Furthermore, when the fifth indication information and the sixth indication information are sent simultaneously, the SMF sends the first indication information to the UPF based on the fifth indication information, including: the SMF sends the first indication information to the UPF based on the fifth indication information and the sixth indication information. In this manner, the SMF determines, based on the fifth indication information, that the first session needs to be switched to the new path, and determines, based on the sixth indication information, that the terminal cannot transmit data with the first RAN node during the path switching. Therefore, under the premise that the transmission agent function has been enabled, the UPF needs to stop transmitting downlink data of the first session.

[0157] It should be noted that the terminal may not send the sixth indication information, that is, the terminal may not indicate to the AMF or SMF whether the terminal supports data transmission with the first RAN node during the path switch of the first session. In the absence of an indication, the AMF or SMF assumes that the terminal does not support data transmission with the first RAN node during the path switch of the first session.

[0158] Optionally, before the SMF receives the fifth indication information, method 500 further includes S508: the SMF sends a second indication information to the UPF, where the second indication information is used to indicate that a transport proxy function is provided for the first session. In this manner, the SMF instructs the UPF to enable the transport proxy function before the path switch of the first session.

[0159] Providing the function of the transmission agent for the first session can be described as enabling the function of the transmission agent for the first session.

[0160] Optionally, S508 specifically includes: the SMF sending second indication information to the UPF based on the sixth indication information. After receiving the sixth indication information, the SMF confirms that the terminal cannot transmit data with the first RAN node during the path switching. Therefore, to ensure service continuity of the first session during the path switching, the SMF may instruct the UPF to provide a transmission agent function for the first session.

[0161] Optionally, before S508, the method 500 further includes S509: the SMF receives seventh indication information from the terminal, where the seventh indication information is used to indicate that the terminal supports path switching of the first session or the terminal supports path switching.

[0162] The terminal's support for path switching for the first session can also be described as the terminal requesting service continuity for the first session during the path switching period. This also means that the terminal requests the SMF to provide service continuity for the first session during the path switching period. In this indication method, the SMF enables the transport proxy function for the first session. In other words, the transport proxy function can be enabled for the terminal's first session. For other sessions initiated by the terminal, such as the second session, the terminal needs to again indicate whether path switching for the second session is supported.

[0163] The terminal supports path switching, which can also be described as the terminal requesting service continuity for its sessions during path switching, where the sessions include the first session. In this indication mode, the SMF controls the activation of the transport proxy function at the terminal granularity. In other words, the SMF can activate the transport proxy function if it determines that the first session is the session of the terminal.

[0164] Furthermore, S508 includes: the SMF sends second indication information to the UPF based on the seventh indication information. In this manner, the SMF determines, based on the seventh indication information, that the terminal requests service continuity for the first session during the path switching period, and further, the SMF instructs the UPF to enable a transport agent function to support service continuity for the first session of the terminal during the path switching period, or to provide service continuity for the first session during the path switching period.

[0165] Optionally, before S508, method 500 further includes S510: the SMF receives eighth indication information, where the eighth indication information is used to indicate that service continuity of the first session during the path switching is supported, or is used to indicate that path switching of the terminal is allowed. Supporting service continuity of the first session during the path switching can also be described as allowing service continuity to be provided for the first session during the path switching.

[0166] Optionally, S510 includes: the SMF receives eighth indication information from the first AMF. The first AMF obtains the eighth indication information from the PCF or UDM. In this manner, during the terminal registration process, the first AMF first obtains the eighth indication information from the PCF or UDM. When the first session is subsequently established, the SMF obtains the eighth indication information from the first AMF.

[0167] Optionally, S510 includes: the SMF receives eighth indication information from the PCF or the UDM. In this manner, when establishing the first session, the SMF obtains the eighth indication information from the PCF or the UDM.

[0168] Further, S508 includes: SMF sends second indication information to UPF based on the eighth indication information.

[0169] Optionally, after the UPF enables the transport agent function for the first session, the SMF sends ninth indication information to the terminal, where the ninth indication information is used to indicate that the first session has the transport agent function or that the first session supports path switching. Accordingly, the terminal receives the ninth indication information. It should be understood that the SMF may send the ninth indication information to the terminal via the first AMF.

[0170] It should be understood that after the UPF turns on the transmission agent function for the first session, it means that the first session has the transmission agent function or the first session supports path switching. The first session supports path switching, which means that the first session supports business continuity during path switching.

[0171] In combination with the description of method 500, the following, in combination with Figures 6 to 10, takes the terminal session as a PDU session (that is, the above-mentioned first session is a PDU session of the terminal), the transmission agent is a TCP agent, and the interaction between the terminal and SMF is through AMF as an example to describe in detail the embodiment of the present application.

[0172] The PCF shown in FIG6 to FIG9 may also be replaced by the UDM, that is, the interaction between other network elements and the PCF may also be replaced by the interaction with the UDM.

[0173] The communication method of the present application will be introduced below from two stages. The first stage includes SMF configuring UPF to enable the transmission agent function for the terminal's PDU session. The second stage includes, based on the SMF configuring UPF to enable the transmission agent function, SMF configures UPF to stop downlink data transmission during the path switching of the PDU session.

[0174] The first phase includes two different implementation processes, which correspond to the method 600 and the method 700 described below. The second phase includes two different implementation processes, which correspond to the method 800 and the method 900 described below.

[0175] The processes of the first and second phases can be implemented in combination to avoid the situation where the UPF mistakenly believes that network congestion has occurred and reduces the data transmission rate during the path switching process of the PDU session.

[0176] For example, after performing the steps described in method 600 , the steps described in method 800 are performed.

[0177] For another example, after performing the steps described in method 600 , the steps described in method 900 are performed.

[0178] For another example, after performing the steps described in method 700 , the steps described in method 800 are performed.

[0179] For another example, after performing the steps described in method 700 , perform the steps described in method 900 .

[0180] The following first introduces a specific process of SMF configuring UPF to enable the transmission agent function for the terminal's PDU session in conjunction with Figure 6.

[0181] FIG6 is a schematic flow chart of a communication method 600 provided in an embodiment of the present application. The method 600 includes S601 to S607, and the specific steps are as follows:

[0182] S601: A terminal sends terminal capability information to a first AMF, where the terminal capability information indicates that the terminal supports path switching. Accordingly, the first AMF receives the terminal capability information.

[0183] Optionally, the terminal sends terminal capability information to the first AMF, including: the terminal sends a registration request message to the first AMF, the registration request message including the terminal capability information, the terminal capability information corresponding to the seventh indication information above, or the seventh indication information above is the terminal capability information.

[0184] The terminal supports path switching, which can also be described as the terminal requesting service continuity to be provided for the PDU session of the terminal during path switching.

[0185] The terminal sends the terminal capability information to the first AMF, specifically including: the terminal sends the terminal capability information to the first AMF through the first RAN node.

[0186] Optionally, when the terminal is authorized to perform path switching, the registration request message includes the terminal capability information to indicate that the terminal supports path switching.

[0187] S602: The first AMF sends a first request message to the PCF, where the first request message is used to request the subscription information or policy control information of the terminal. In response, the PCF receives the first request message.

[0188] S603: The PCF sends a first response message to the first AMF. The first response message includes information indicating support for service continuity of the PDU session during path switching, which corresponds to the eighth indication information above. Accordingly, the first AMF receives the first response message.

[0189] Optionally, the first AMF stores the information indicating support for service continuity of the PDU session during path switching in the context of the terminal based on the received terminal capability information.

[0190] In the above S601 to S603, the terminal carries the terminal capability information during the process of registering with the network, indicating that the terminal supports path switching. Furthermore, the first AMF determines, based on the first response message, whether to support the service continuity of the PDU session of the terminal during the path switching, or to allow the provision of service continuity for the PDU session of the terminal during the path switching. In this way, when the terminal subsequently requests to establish a PDU session, the first AMF can instruct the SMF to provide service continuity for the PDU session of the terminal during the path switching, and then the SMF turns on the TCP transport agent function for the PDU session, thereby supporting the service continuity of the PDU session of the terminal during the path switching, see the steps below.

[0191] S604: The terminal sends a NAS message to the first AMF. Correspondingly, the first AMF receives the NAS message.

[0192] Specifically, the terminal sends the NAS message to the first AMF through the first RAN node. The NAS message includes but is not limited to: a PDU session identifier, a PDU session establishment request message, a DNN, and an S-NSSAI. Among them, the PDU session establishment request message includes a PDU session identifier, session and service continuity (SSC) mode information, etc.

[0193] From this step, the terminal begins to establish a PDU session.

[0194] S605: The first AMF sends information indicating support for service continuity of the PDU session during path switching to the SMF. Correspondingly, the SMF receives the information indicating support for service continuity of the PDU session during path switching.

[0195] Optionally, the information indicating support for service continuity of the PDU session during path switching is carried in a request message for creating a PDU session management context (PDUSession_CreateSMContext request). The request message for creating a PDU session management context also includes, but is not limited to, SUPI, DNN, S-NSSAI, and PDU session establishment request messages.

[0196] Optionally, before this step, the first AMF selects an SMF that supports path switching from at least one SMF. The SMF in this step is the SMF that supports path switching.

[0197] S606: The SMF sends information to the UPF indicating that a transport agent function is provided for the PDU session, which corresponds to the second indication information mentioned above. Accordingly, the UPF receives the information indicating that a transport agent function is provided for the PDU session.

[0198] Optionally, the information for indicating the function of providing a transport agent for the PDU session is carried in an N4 session establishment request message.

[0199] Optionally, before this step, the SMF may select a UPF that supports TCP transport agent from at least one UPF. The UPF in this step is the UPF that supports TCP transport agent.

[0200] Optionally, before this step, the SMF determines to enable the TCP transmission agent function for the PDU session of the terminal according to the eighth indication information above.

[0201] Optionally, before this step, the SMF determines to enable the TCP transmission agent function for the PDU session of the terminal according to the seventh indication information above.

[0202] After the UPF turns on the TCP transmission agent function, the SMF records that the UPF has turned on the TCP transmission agent function, so that the SMF can subsequently perform relevant configurations on the UPF, for example, configuring the UPF to stop or start downlink data transmission of the PDU session.

[0203] S607: The SMF sends information indicating that the PDU session has a transmission agent function to the terminal, which corresponds to the ninth indication information mentioned above. Accordingly, the terminal receives the information indicating that the PDU session has a transmission agent function.

[0204] In this step, the information indicating that the PDU session has the function of a transport agent may be replaced by information indicating that the PDU session supports path switching. The terminal may subsequently initiate a path switching process based on the information indicating that the PDU session has the function of a transport agent. For details, see method 800 or method 900 below, which will not be described in detail here.

[0205] In an embodiment of the present application, during the process of terminal registration with the network, the terminal sends terminal capability information to the first AMF. After determining that the service continuity of the PDU session of the terminal is supported during the path switch, the first AMF can indicate to the SMF that the service continuity of the PDU session of the terminal is supported during the path switch when requesting the SMF to establish the PDU session. Furthermore, the SMF can configure the UPF to enable the TCP transport agent function for the PDU session.

[0206] In an embodiment of the present application, SMF controls the activation of the TCP transport agent function based on terminal granularity. That is, when SMF obtains information indicating the support of business continuity of PDU sessions during path switching, it can determine the support of business continuity of any PDU session of the terminal during path switching.

[0207] The following describes another specific process of SMF configuring UPF to enable the transmission agent function for the terminal's PDU session in conjunction with Figure 7.

[0208] Figure 7 is a schematic flow chart of another communication method 700 provided in an embodiment of the present application. Before method 700, the terminal performs a registration process, and the first AMF is responsible for the access and mobility management of the terminal and the registration management of the terminal.

[0209] Optionally, during the process of the terminal registering the network, the terminal receives a tenth indication message from the first AMF, where the tenth indication message is used to indicate that the terminal is authorized for path switching.

[0210] Different from method 600, during the process of terminal registration with the network, the terminal may not send the terminal capability information temporarily, but may send the terminal capability information or terminal requirement information during the subsequent process of establishing a certain PDU session.

[0211] The method 700 includes steps S701 to S705, and the specific steps are as follows:

[0212] S701: A terminal sends terminal capability information or terminal requirement information to a first AMF. Accordingly, the first AMF receives the terminal capability information or the terminal requirement information.

[0213] The terminal capability information corresponds to the seventh indication information mentioned above, indicating that the terminal supports path switching.

[0214] Alternatively, the terminal requirement information corresponds to the seventh indication information above, indicating that the terminal supports path switching of the PDU session, or in other words, indicating that the terminal supports business continuity of the PDU session during path switching, or in other words, requesting business continuity to be provided for the PDU session during path switching.

[0215] Optionally, S701 includes: the terminal sending a NAS message to the first AMF through the first RAN node, where the NAS message includes the terminal capability information or the terminal requirement information. The NAS message further includes but is not limited to: a PDU session identifier, a PDU session establishment request message, a DNN, and an S-NSSAI.

[0216] Optionally, when the terminal receives the tenth indication information, the terminal carries the terminal capability information or the terminal requirement information in a NAS message.

[0217] Optionally, the first AMF selects an SMF that supports path switching from at least one SMF according to the terminal capability information or the terminal requirement information, and performs the operation of S702.

[0218] S702: The first AMF sends the terminal capability information or the terminal requirement information to the SMF. Correspondingly, the SMF receives the terminal capability information or the terminal requirement information.

[0219] Optionally, S702 includes: the first AMF sends a request message for creating a context for PDU session management to the SMF, and the request message for creating the context for PDU session management includes the terminal capability information or the terminal requirement information.

[0220] For an introduction to the terminal capability information and the terminal requirement information, please refer to the description in S701 and will not be repeated here.

[0221] S703, SMF sends information for indicating the function of providing a transport agent for the PDU session to UPF, which corresponds to the second indication information mentioned above. Correspondingly, UPF receives the information for indicating the function of providing a transport agent for the PDU session.

[0222] The UPF in this step is a UPF that supports the TCP transmission agent function.

[0223] The information used to indicate the function of providing a transport agent for a PDU session may also be described as information used to indicate the function of enabling a TCP transport agent for a PDU session.

[0224] The SMF records that the PDU session adopts the TCP transport agent function, that is, the UPF has enabled the TCP transport agent function for the PDU session.

[0225] Optionally, S703 includes: SMF sends an N4 session establishment request message to UPF, and the N4 session establishment request message carries information for indicating the function of providing a transmission agent for the PDU session.

[0226] Optionally, before S703 , the method 700 further includes S705 : the SMF receives information from the PCF or the UDM indicating support for service continuity of the PDU session during path switching, where the information corresponds to the eighth indication information mentioned above.

[0227] Specifically, the SMF sends the parameters of the PDU session, such as DNN, S-NSSAI, and SSC mode, to the PCF or UDM. The PCF or UDM determines whether to support business continuity of the PDU session during path switching based on the parameters of the PDU session, or determines whether to allow business continuity to be provided for the PDU session during path switching.

[0228] Exemplarily, service continuity of a PDU session corresponding to a pre-configured DNN or S-NSSAI is supported during path switching.

[0229] Exemplarily, when the SSC mode of the PDU session indicates support for service continuity, the PCF or UDM determines to support service continuity of the PDU session during path switching.

[0230] Exemplarily, the PCF or UDM determines to support service continuity of the PDU session during path switching according to the session subscription information of the terminal.

[0231] Optionally, before S703, the SMF determines whether to enable the TCP transport proxy function for the PDU session based on one or more of the following information: terminal capability information, terminal requirement information, DNN configuration information, or information indicating support for service continuity of the PDU session during path switching. The DNN configuration information indicates the use of the TCP transport proxy function when accessing the DNN.

[0232] Exemplarily, the SMF receives terminal capability information or terminal requirement information, and the DNN configuration information indicates that the DNN corresponding to the PDU session can use the TCP transport agent function, and then the SMF determines to enable the TCP transport agent function for the PDU session.

[0233] Exemplarily, the SMF receives terminal capability information or terminal requirement information, and receives information from the PCF or UMD indicating support for service continuity of the PDU session during path switching, and then the SMF determines to enable the TCP transport agent function for the PDU session.

[0234] Exemplarily, during the path switching process of the PDU session, the terminal does not support data transmission with the first RAN node after connecting to the second RAN node. In this case, the terminal indicates to the SMF through the first AMF that the terminal does not support data transmission with the first RAN node during the path switching of the PDU session. Then, the SMF determines to enable the TCP transmission agent function for the PDU session.

[0235] S704: The SMF sends information indicating that the PDU session has a transmission agent function to the terminal, which may be the ninth indication information mentioned above. Accordingly, the terminal receives the information indicating that the PDU session has a transmission agent function.

[0236] The terminal stores the information indicating that the PDU session has the function of a transmission agent. The terminal can subsequently initiate a path switching process based on the information indicating that the PDU session has the function of a transmission agent. For details, please refer to method 800 or method 900 below, which will not be described in detail here.

[0237] Optionally, method 700 further includes: the SMF sending the UPF's IP address to the terminal through the first AMF. After the terminal receives the UPF's IP address, it establishes a first TCP connection with the UPF. The terminal then requests the UPF to establish a TCP connection with the server. The UPF establishes a second TCP connection with the server as a TCP proxy. Furthermore, the UPF transmits data between the terminal and the server as a TCP proxy.

[0238] In an embodiment of the present application, during the process of establishing a PDU session at the terminal, the SMF determines to enable the TCP transmission agent function for the PDU session. Further, the SMF configures the UPF to enable the TCP transmission agent function.

[0239] In an embodiment of the present application, SMF controls the activation of the TCP transport agent function based on the PDU session granularity. That is, the activation of the TCP transport agent function is for certain PDU sessions. In other words, the TCP transport agent function is only activated for certain PDU sessions. This is conducive to increasing the flexibility of activating the TCP transport agent function.

[0240] The above describes two different implementation processes of the first phase in conjunction with Figures 6 and 7. The following describes a specific process in which the SMF configures the UPF to stop downlink data transmission during the path switching of the PDU session in conjunction with Figure 8.

[0241] FIG8 is a schematic flow chart of another communication method 800 provided in an embodiment of the present application. In the method 800 , after the terminal accesses the second RAN node, the terminal does not support data transmission with the first RAN node.

[0242] The method 800 includes steps S801 to S811, and the specific steps are as follows:

[0243] S801: The terminal sends a request type for the PDU session to the second AMF, where the request type for the PDU session is a handover indication or an existing PDU session. Correspondingly, the second AMF receives the request type for the PDU session.

[0244] When the request type of the PDU session is a switching indication or an existing PDU session, the SMF determines that a path switching is required for the PDU session. The request type of the PDU session, i.e., the switching indication or the existing PDU session, corresponds to the fifth indication information above, or the fifth indication information above is the switching indication or the existing PDU session.

[0245] Optionally, S801 may specifically include: the terminal sends a NAS message to the second AMF through the second RAN node, where the NAS message includes the request type of the PDU session and the identifier of the PDU session.

[0246] Optionally, the NAS message further includes information for indicating that the terminal does not support data transmission with the first RAN node during the path switch of the PDU session, and this information corresponds to the sixth indication information mentioned above.

[0247] S802: The second AMF sends the request type of the PDU session to the SMF. Correspondingly, the SMF receives the request type of the PDU session.

[0248] Optionally, S802 includes: the SMF sends a request message for updating the context of PDU session management (PDUSession_UpdateSMContext request) to the UPF, where the request message for updating the context of PDU session management includes the request type of the PDU session and the identifier of the PDU session.

[0249] Optionally, the request message for updating the context of the PDU session management further includes information for indicating that the terminal does not support data transmission with the first RAN node during the path switch of the PDU session.

[0250] In conjunction with the description in method 600 or method 700 above, during the establishment of the PDU session, the SMF records that the PDU session adopts the TCP transport agent function, that is, the UPF provides the transport agent function for the PDU session. If the SMF determines that the UPF provides the transport agent function for the PDU session, it executes S803 based on the request type of the PDU session received in S801.

[0251] S803, the SMF sends information for instructing the UPF to stop the downlink data transmission of the PDU session, which corresponds to the first instruction information mentioned above. Correspondingly, the UPF receives the information for instructing the UPF to stop the downlink data transmission of the PDU session.

[0252] After receiving the information for instructing to stop the downlink data transmission of the PDU session, the UPF stops the downlink data transmission between the terminal and the terminal. Specifically, the UPF stops sending the downlink data of the PDU session to the first RAN node through the first TCP connection.

[0253] The UPF stores the TCP parameters used when stopping sending downlink data of the PDU session to the first RAN node through the first TCP connection, such as the send window, data transmission rate, and other parameters. The second TCP connection between the UPF and the server is not affected. The UPF can continue to receive downlink data of the PDU session transmitted through the second TCP connection and cache the downlink data of the PDU session transmitted through the second TCP connection.

[0254] Optionally, S803 includes: the SMF sends an N4 modification message (N4 modification) to the UPF, where the N4 modification message includes information for indicating stopping downlink data transmission of the PDU session.

[0255] Optionally, the SMF also configures the UPF with a first duration for caching the downlink data of the PDU session.

[0256] S804: UPF sends core network tunnel information (CN tunnel information) to SMF. The core network tunnel information includes the IP address and port number used by UPF to receive uplink data. Correspondingly, SMF receives the core network tunnel information.

[0257] S805: The SMF sends the core network tunnel information and the QoS profile to the second RAN node via the second AMF. Correspondingly, the second RAN node receives the core network tunnel information and the QoS profile.

[0258] The QoS file includes the QoS parameters of the PDU session.

[0259] S806 : The second RAN node interacts with the terminal for air interface configuration for data transmission.

[0260] S807: The second RAN node sends access network tunnel information (AN tunnel information) to the UPF. The access network tunnel information includes the IP address and port number of the second RAN node for receiving downlink data. Accordingly, the UPF receives the access network tunnel information.

[0261] Specifically, the second RAN node sends the access network tunnel information to the UPF through the second AMF and SMF.

[0262] The access network tunnel information in this step may be the fourth indication information mentioned above.

[0263] Optionally, after S807, method 800 further includes S808: the SMF sends information to the UPF for instructing the start of downlink data transmission for the PDU session, which may correspond to the fourth indication information mentioned above. That is, after sending the access network tunnel information to the UPF, the SMF may further send information to the UPF for instructing the start of downlink data transmission for the PDU session, and the UPF starts sending downlink data of the PDU session to the second RAN node based on the information.

[0264] S809: The UPF sends the downlink data of the PDU session to the second RAN node. Correspondingly, the second RAN node receives the downlink data of the PDU session.

[0265] In this step, after receiving the access network tunnel information, the UPF determines that the path switching of the PDU session has been completed. Therefore, the UPF can start sending the downlink data of the PDU session to the second RAN node based on the access network tunnel information.

[0266] Specifically, the UPF determines the address information of the second RAN node based on the access network tunnel information, including the IP address and port number. The UPF then sends the downlink data for the PDU session to the second RAN node via the first TCP connection according to the stored TCP connection parameters. The first TCP connection is the TCP connection between the terminal and the UPF. After the path switch for the PDU session is completed, the data transmitted between the terminal and the UPF over the first TCP connection passes through the second RAN node.

[0267] S810: The second RAN node sends downlink data of the PDU session to the terminal. Correspondingly, the terminal receives the downlink data of the PDU session.

[0268] During the above S803 to S807, the first TCP connection between the terminal and the UPF is temporarily interrupted, and the second TCP connection between the UPF and the server is normal, and data transmission can be carried out normally, including the UPF receiving the downlink data of the PDU session through the second TCP connection, and the UPF sending ACK feedback for the downlink data to the server through the second TCP connection. The UPF caches the downlink data received from the server without using slow start, which can avoid the UPF constantly trying to reduce the data transmission rate to send downlink data to the terminal. After the connection between the terminal and the UPF is restored, the UPF can send the cached downlink data and the subsequently received downlink data to the terminal at the original data transmission rate.

[0269] S811: The SMF triggers the release of communication resources of the original path (i.e., the path passing through the first RAN node). The resources of the original path include communication resources between the terminal and the first RAN node, and communication resources between the first RAN node and the UPF.

[0270] Specifically, the SMF sends an N2 session management resource release request message to the first RAN node through the first AMF. The N2 session management resource release request message includes the identifier of the PDU session. After receiving the N2 session management resource release request message, the first RAN node releases the context information of the PDU session associated with the identifier of the PDU session.

[0271] Optionally, S811 may be executed after S803 or after S810, which is not limited in the embodiment of the present application.

[0272] In an embodiment of the present application, the terminal triggers a path switching process for the PDU session through the second RAN node. For a scenario in which the terminal no longer supports data transmission with the first RAN node after accessing the second RAN node, the SMF instructs the UPF to stop downlink data transmission of the PDU session. This can avoid the situation in which the UPF continuously attempts to reduce the data transmission rate to send the downlink data of the PDU session to the terminal, but the terminal cannot receive it, thereby improving communication performance.

[0273] In another scenario, after the terminal accesses the second RAN node, it can also support data transmission with the first RAN node. In other words, after the terminal accesses the second RAN node, it can also connect to the first RAN node for data transmission at the same time.

[0274] In this scenario, the terminal indicates to the second AMF via the second RAN node that data transmission with the first RAN node is supported after the terminal accesses the second RAN node. Furthermore, the second AMF indicates to the SMF that data transmission with the first RAN node is supported after the terminal accesses the second RAN node. In this case, the first AMF and SMF do not temporarily release the original path, and the SMF does not execute S803 above. After the process of establishing the new path (the path passing through the second RAN node) described in S804 to S807 above is completed, the first AMF and SMF release the original path.

[0275] 9 , another specific process of configuring the UPF to stop downlink data transmission during path switching of a PDU session by the SMF is described below.

[0276] Figure 9 is a schematic flow chart of another communication method 900 provided in an embodiment of the present application. In method 900, after a terminal accesses a second RAN node, the terminal does not support data transmission with the first RAN node. This method differs from method 800 described above in that in method 900, the terminal sends information indicating a path for switching the terminal's PDU session over the original path.

[0277] The above method 600 or method 700 may be implemented before method 900. Method 900 includes S901 to S914, and the specific steps are as follows:

[0278] S901: The terminal sends information indicating a PDU session handover path for the terminal to the first AMF, corresponding to the fifth indication information above. Accordingly, the first AMF receives the information indicating a PDU session handover path for the terminal.

[0279] Specifically, the terminal sends the information indicating the PDU session switching path of the terminal to the first AMF through the first RAN node.

[0280] In this step, since the path switching process of the PDU session has not been triggered yet, the information used to indicate the path switching for the PDU session of the terminal can be understood as information used to indicate the preparation for switching the path of the PDU session of the terminal or path switching preparation indication information.

[0281] As can be seen from the above description of method 600 or method 700, during the process of establishing the PDU session, the terminal receives information from the SMF indicating that the PDU session has a transport agent function or information indicating that the PDU session supports path switching. The terminal executes S901 based on the information.

[0282] In this step, the terminal also sends the identifier of the PDU session to the first RAN node.

[0283] S902, the first AMF sends information indicating the PDU session switching path for the terminal and the identifier of the session management context (SM Context ID) to the SMF. Correspondingly, the SMF receives the identifier of the session management context and the information indicating the PDU session switching path for the terminal.

[0284] In this step, the identifier of the session management context is used to identify the PDU session of the terminal between the first AMF and the SMF.

[0285] S903, the SMF sends information for instructing the UPF to stop the downlink data transmission of the PDU session. Correspondingly, the UPF receives the information for instructing the UPF to stop the downlink data transmission of the PDU session.

[0286] Specifically, the UPF stops sending the downlink data of the PDU session to the first RAN node through the first TCP connection.

[0287] Similar to the description in the above method 800, the SMF may further indicate to the UPF the first duration for caching the downlink data of the PDU session, and the UPF may further store the TCP parameters used when stopping the downlink data transmission of the PDU session.

[0288] S904: The terminal sends a request type for the PDU session to the second AMF, where the request type for the PDU session is a handover indication or an existing PDU session. Accordingly, the second AMF receives the request type for the PDU session.

[0289] In this step, the terminal sends the request type of the PDU session to the second AMF through the second RAN node. For an introduction to the request type, please refer to the description in S801 above and will not be repeated here.

[0290] It should be understood that this step is a step for triggering the path switching of the PDU session. Before this step, the UPF has stopped the downlink data transmission of the PDU session.

[0291] S905: The second AMF sends the request type of the PDU session to the SMF. Correspondingly, the SMF receives the request type of the PDU session.

[0292] S906: The SMF sends an N4 modification message to the UPF. Correspondingly, the UPF receives the N4 modification message.

[0293] S907: UPF sends core network tunnel information to SMF. The core network tunnel information includes the IP address and port number used by UPF to receive uplink data. Correspondingly, SMF receives the core network tunnel information.

[0294] S908: The SMF sends the core network tunnel information and the QoS profile to the second RAN node via the second AMF. Correspondingly, the second RAN node receives the core network tunnel information and the QoS profile.

[0295] S909 : The second RAN node interacts with the terminal for air interface configuration for data transmission.

[0296] S910: The second RAN node sends access network tunnel information to the UPF via the second AMF and SMF. The access network tunnel information includes the IP address and port number used by the second RAN node to receive downlink data. Accordingly, the UPF receives the access network tunnel information.

[0297] The access network tunnel information in this step corresponds to the fourth indication information mentioned above.

[0298] Optionally, after S910, method 900 further includes S911: the SMF sends information to the UPF for instructing the start of downlink data transmission for the PDU session, where the information corresponds to the fourth indication information mentioned above. That is, after sending the access network tunnel information to the UPF, the SMF may further send information to the UPF for instructing the start of downlink data transmission for the PDU session, and the UPF starts sending downlink data of the PDU session to the second RAN node based on the information.

[0299] S912: The UPF sends the downlink data of the PDU session to the second RAN node. Correspondingly, the second RAN node receives the downlink data of the PDU session.

[0300] S913: The second RAN node sends the downlink data of the PDU session to the terminal. Correspondingly, the terminal receives the downlink data of the PDU session.

[0301] S914: The SMF triggers the release of communication resources along the original path (i.e., passing through the first RAN node). The resources along the original path include communication resources between the terminal and the first RAN node, and communication resources between the first RAN node and the UPF.

[0302] For the introduction of this step, please refer to the description of S811 above, which will not be repeated here.

[0303] In this embodiment of the present application, before a terminal accesses a second RAN node, it first indicates a path switch for its PDU session via the original path. After the SMF instructs the UPF to stop downlink data transmission for the PDU session, the terminal triggers a path switch process for the PDU session via the new path. Method 900 can avoid the loss of downlink data already sent by the UPF between the time the terminal accesses the second RAN node and the time the UPF receives information indicating the stop of downlink data transmission for the PDU session, thereby further improving service continuity.

[0304] It should be understood that the size of the serial numbers of the above processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0305] The communication method according to the embodiment of the present application is described in detail above in conjunction with Figures 5 to 9. The communication device according to the embodiment of the present application will be described in detail below in conjunction with Figures 10 and 11.

[0306] FIG10 is a schematic block diagram of a communication device 1000 provided in an embodiment of the present application. The device 1000 includes a transceiver module 1010. Optionally, the device 1000 further includes a processing module 1020.

[0307] The processing module 1020 is used to perform data processing. The transceiver module 1010 can implement corresponding communication functions. The transceiver module 1010 can also be called a communication interface or a communication module.

[0308] Optionally, the device 1000 may further include a storage module, which may be used to store data and / or to store computer programs or instructions. The processing module 1020 may read the computer programs / instructions and / or data in the storage module so that the device 1000 implements the above-mentioned method embodiment.

[0309] Device 1000 can be used to execute the actions performed by the UPF, SMF, or terminal in the above-described method embodiments. Device 1000 can be a UPF, SMF, or terminal. Alternatively, device 1000 can be a component (e.g., a chip) configured in a UPF, SMF, or terminal. Processing module 1020 is used to execute operations related to processing by the UPF, SMF, or terminal in the above-described method embodiments. Transceiver module 1010 is used to execute operations related to receiving and sending by the UPF, SMF, or terminal in the above-described method embodiments.

[0310] Optionally, the transceiver module 1010 may include a sending module and a receiving module. The sending module is used to perform the sending operation in the above method embodiment. The receiving module is used to perform the receiving operation in the above method embodiment.

[0311] It should be noted that the apparatus 1000 may include a sending module but not a receiving module. Alternatively, the apparatus 1000 may include a receiving module but not a sending module. The specific implementation depends on whether the above solution executed by the apparatus 1000 includes a sending action and a receiving action.

[0312] Optionally, the apparatus 1000 is configured to execute the actions executed by the UPF, SMF, or terminal in the embodiments shown in Figures 5 to 9. For details, please refer to the relevant introductions in the embodiments shown in Figures 5 to 9, which will not be repeated here.

[0313] In one embodiment, the apparatus 1000 is configured to perform the following scheme:

[0314] The transceiver module 1010 is configured to receive first indication information from the SMF, the first indication information being used to instruct to stop downlink data transmission of a first session of the terminal. The processing module 1020 is configured to stop sending downlink data of the first session to a first RAN node based on the first indication information, the first RAN node being the RAN node used to transmit data of the first session before path switching of the first session.

[0315] Optionally, the transceiver module 1010 is configured to receive second indication information from the SMF, where the second indication information is used to indicate providing a transport agent function for the first session, where the transport agent is a TCP connection transport agent, or the transport agent is a QUIC transport agent. The processing module 1020 is configured to provide the transport agent function for the first session based on the second indication information.

[0316] Optionally, the processing module 1020 is used to: stop sending downlink data of the first session to the first RAN node through the first communication connection, where the first communication connection is a TCP connection or a QUIC connection between the terminal and the UPF.

[0317] Optionally, the transceiver module 1010 is configured to receive downlink data of the first session transmitted via a second communication connection. The processing module 1020 is configured to cache the downlink data of the first session transmitted on the second communication connection. The second communication connection is a TCP connection or a QUIC connection between the UPF and the server.

[0318] Optionally, the transceiver module 1010 is used to: receive third indication information from the SMF, where the third indication information is used to indicate a first duration, where the first duration is a duration for caching downlink data of the first session.

[0319] Optionally, the transceiver module 1010 is configured to: receive fourth indication information from the SMF, the fourth indication information being used to indicate the start of downlink data transmission for the first session; and, based on the fourth indication information, send the downlink data of the first session to the second RAN node via the first communication connection in accordance with stored communication connection parameters. The communication connection parameters are communication connection parameters used when stopping sending downlink data of the first session to the first RAN node via the first communication connection, and the second RAN node is the RAN node used to transmit data of the first session after path switching for the first session.

[0320] In this embodiment, those skilled in the art will appreciate that device 1000 can be specifically the UPF in the above-mentioned embodiments, or the functions of the UPF in the above-mentioned embodiments can be integrated into device 1000. The above-mentioned functions can be implemented via hardware, or by hardware executing corresponding software. The hardware or software includes one or more modules corresponding to the above-mentioned functions. Device 1000 can be used to execute the various processes and / or steps corresponding to the UPF in the above-mentioned method embodiments.

[0321] In another possible embodiment, the apparatus 1300 is configured to execute the following solution:

[0322] The transceiver module 1010 is configured to: receive fifth indication information, the fifth indication information being used to indicate a path switching for a first session of the terminal; and, if it is determined that the UPF provides a transport agent function for the first session, send first indication information to the UPF based on the fifth indication information. The first indication information is used to indicate stopping downlink data transmission for the first session, where the transport agent is a TCP connection transport agent or a QUIC transport agent.

[0323] Optionally, the transceiver module 1010 is used to: send third indication information to the UPF, where the third indication information is used to indicate a first duration, where the first duration is the duration for caching the downlink data of the first session.

[0324] Optionally, the transceiver module 1010 is used to: receive sixth indication information, where the sixth indication information is used to indicate that the terminal does not support data transmission with the first RAN node during the path switching of the first session, where the first RAN node is the RAN node used to transmit data of the first session before the path switching of the first session.

[0325] Optionally, the transceiver module 1010 is used to: send the first indication information to the UPF based on the fifth indication information and the sixth indication information.

[0326] Optionally, the transceiver module 1010 is used to: send second indication information to the UPF, where the second indication information is used to indicate the function of providing the transmission agent for the first session.

[0327] Optionally, the transceiver module 1010 is used to: send the second indication information to the UPF based on the sixth indication information.

[0328] Optionally, the transceiver module 1010 is used to: receive seventh indication information, where the seventh indication information is used to indicate that the terminal supports path switching for the first session or the terminal supports path switching; and, based on the seventh indication information, send the second indication information to the UPF.

[0329] Optionally, the transceiver module 1010 is used to: receive eighth indication information, where the eighth indication information is used to indicate support for service continuity of the first session during path switching; and, based on the seventh indication information, send the second indication information to the UPF.

[0330] Optionally, the transceiver module 1010 is configured to: send ninth indication information to the terminal, where the ninth indication information is used to indicate that the first session has the function of the transmission agent or that the first session supports path switching.

[0331] Optionally, the transceiver module 1010 is used to: send fourth indication information to the UPF, where the fourth indication information is used to indicate the start of downlink data transmission of the first session.

[0332] In this embodiment, those skilled in the art will appreciate that device 1000 can be specifically the SMF in the above-mentioned embodiment, or the functions of the SMF in the above-mentioned embodiment can be integrated into device 1000. The above-mentioned functions can be implemented by hardware, or by hardware executing corresponding software. The hardware or software includes one or more modules corresponding to the above-mentioned functions. Device 1000 can be used to execute the various processes and / or steps corresponding to the SMF in the above-mentioned method embodiments.

[0333] In another possible embodiment, the apparatus 1300 is configured to execute the following solution:

[0334] The transceiver module 1010 is used to: receive ninth indication information, where the ninth indication information is used to indicate that the first session of the terminal has the function of a transmission agent or that the first session supports path switching, and the transmission agent is a TCP connection transmission agent, or the transmission agent is a QUIC transmission agent; and, based on the ninth indication information, send fifth indication information, where the fifth indication information is used to indicate the switching path of the first session of the terminal.

[0335] Optionally, the transceiver module 1010 is configured to: send the fifth indication information through a first RAN node, where the first RAN node is a RAN node used to transmit data of the first session before the path switching of the first session.

[0336] Optionally, the transceiver module 1010 is configured to: send the fifth indication information through a second RAN node, where the second RAN node is a RAN node used to transmit data of the first session after the path switch of the first session.

[0337] Optionally, the transceiver module 1010 is used to: send sixth indication information, where the sixth indication information is used to indicate that the terminal does not support data transmission with the first RAN node during the path switching of the first session, where the first RAN node is the RAN node used to transmit data of the first session before the path switching of the first session.

[0338] Optionally, the transceiver module 1010 is configured to: send seventh indication information, where the seventh indication information is used to indicate that the terminal supports path switching of the first session or that the terminal supports path switching.

[0339] In this embodiment, those skilled in the art will appreciate that device 1000 can be specifically the terminal in the above-mentioned embodiments, or the functions of the terminal in the above-mentioned embodiments can be integrated into device 1000. The above-mentioned functions can be implemented through hardware, or through hardware executing corresponding software. The hardware or software includes one or more modules corresponding to the above-mentioned functions. Device 1000 can be used to execute the various processes and / or steps corresponding to the terminal in the above-mentioned method embodiments.

[0340] It should be understood that the apparatus 1000 herein is embodied in the form of functional modules. The term "module" herein may refer to an application specific integrated circuit (ASIC), an electronic circuit, a processor (e.g., a shared processor, a dedicated processor, or a group processor, etc.) and memory for executing one or more software or firmware programs, combined logic circuits, and / or other suitable components that support the described functionality.

[0341] In the embodiment of the present application, the device 1000 may also be a chip or a chip system, such as a system on chip (SoC). Correspondingly, the transceiver module may be a transceiver circuit of the chip, which is not limited here.

[0342] Figure 11 is a schematic block diagram of another communication device 1100 provided in an embodiment of the present application. The device 1100 includes a processor 1110, a transceiver 1120, and a memory 1130. The processor 1110, the transceiver 1120, and the memory 1130 communicate with each other via an internal connection path. The memory 1130 is used to store instructions, and the processor 1110 is used to execute the instructions stored in the memory 1130 to control the transceiver 1120 to send and / or receive signals.

[0343] It should be understood that the device 1100 can be specifically the UPF, SMF or terminal in the above-mentioned embodiments, or the functions of the UPF, SMF or terminal in the above-mentioned embodiments can be integrated into the device 1100, and the device 1100 can be used to execute the various steps and / or processes corresponding to the UPF, SMF or terminal in the above-mentioned method embodiments. Optionally, the memory 1130 may include a read-only memory and a random access memory, and provide instructions and data to the processor. A portion of the memory may also include a non-volatile random access memory. For example, the memory may also store information about the device type. The processor 1110 can be used to execute the instructions stored in the memory, and when the processor executes the instructions, the processor 1110 can execute the various steps and / or processes corresponding to the UPF, SMF or terminal in the above-mentioned method embodiments.

[0344] It should be understood that in the embodiments of the present application, the processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), ASICs, field programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor.

[0345] During implementation, each step of the above method can be completed by an integrated logic circuit of hardware in a processor or by instructions in the form of software. The steps of the method disclosed in conjunction with the embodiments of the present application can be directly embodied as being executed by a hardware processor, or can be executed by a combination of hardware and software modules in the processor. The software module can be located in a storage medium mature in the art, such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory, or an electrically erasable programmable memory, a register, etc. The storage medium is located in a memory, and the processor executes the instructions in the memory, and completes the steps of the above method in conjunction with its hardware. To avoid repetition, it will not be described in detail here.

[0346] Those skilled in the art will appreciate that the modules and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0347] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and modules described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0348] In the several embodiments provided in this application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are merely schematic. For example, the division of the modules is merely a logical function division. In actual implementation, there may be other division methods, such as multiple modules or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or modules, which can be electrical, mechanical or other forms.

[0349] The modules described as separate components may or may not be physically separate, and the components shown as modules may or may not be physical modules, that is, they may be located in one place or distributed across multiple network modules. Some or all of the modules may be selected to achieve the purpose of the present embodiment according to actual needs.

[0350] In addition, each functional module in each embodiment of the present application may be integrated into one processing module, or each module may exist physically separately, or two or more modules may be integrated into one module.

[0351] If the functions are implemented in the form of software function modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0352] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A communication method, characterized in that, including: receiving first indication information from a session management function network element, where the first indication information is used to indicate stopping the downlink data transmission of a first session of a terminal; based on the first indication information, stopping sending the downlink data of the first session to a first radio access network node, where the first radio access network node is a radio access network node used to transmit the data of the first session before the path switching of the first session.

2. The method according to claim 1, characterized in that, The method further includes: receiving second indication information from the session management function network element, where the second indication information is used to indicate a function of providing a transmission proxy for the first session, and the transmission proxy is a transmission control protocol connection transmission proxy, or the transmission proxy is a quick user datagram protocol network connection transmission proxy; based on the second indication information, providing the function of the transmission proxy for the first session.

3. The method according to claim 2, wherein The stopping sending the downlink data of the first session to the first radio access network node includes: stopping sending the downlink data of the first session to the first radio access network node through a first communication connection, where the first communication connection is a transmission control protocol connection or a quick user datagram protocol network connection between the terminal and a user plane function network element.

4. The method according to claim 3, wherein After the stopping sending the downlink data of the first session to the first radio access network node through the first communication connection, the method further includes: receiving the downlink data of the first session transmitted through a second communication connection; caching the downlink data of the first session transmitted on the second communication connection; where the second communication connection is a transmission control protocol connection or a quick user datagram protocol network connection between the user plane function and a server.

5. The method according to any one of claims 1 to 4, characterized in that, The method further includes: receiving third indication information from the session management function network element, where the third indication information is used to indicate a first duration, and the first duration is the duration for caching the downlink data of the first session.

6. The method according to claim 3 or 4, characterized in that, After the stopping sending the downlink data of the first session to the first radio access network node through the first communication connection, the method further includes: receiving fourth indication information from the session management function network element, where the fourth indication information is used to indicate starting the downlink data transmission of the first session; based on the fourth indication information, sending the downlink data of the first session to a second radio access network node through the first communication connection according to stored communication connection parameters; where the communication connection parameters are the communication connection parameters used when stopping sending the downlink data of the first session to the first radio access network node through the first communication connection, and the second radio access network node is a radio access network node used to transmit the data of the first session after the path switching of the first session.

7. A communication method, characterized in that including: receiving fifth indication information, where the fifth indication information is used to indicate switching the path of a first session of a terminal; When it is determined that the user plane function network element provides the function of a transmission proxy for the first session, based on the fifth indication information, send first indication information to the user plane function network element, where the first indication information is used to indicate to stop the downlink data transmission of the first session, and the transmission proxy is a Transmission Control Protocol connection transmission proxy, or the transmission proxy is a Quick User Datagram Protocol network connection transmission proxy.

8. The method according to claim 7, wherein The method further includes: Send third indication information to the user plane function network element, where the third indication information is used to indicate a first duration, and the first duration is the duration for caching the downlink data of the first session.

9. The method according to claim 7 or 8, characterized in that, The method further includes: Receive sixth indication information, where the sixth indication information is used to indicate that the terminal does not support transmitting data with the first radio access network node during the path switching of the first session, and the first radio access network node is the radio access network node used to transmit the data of the first session before the path switching of the first session.

10. The method according to claim 9, characterized in that The sending the first indication information to the user plane function network element based on the fifth indication information includes: Based on the fifth indication information and the sixth indication information, send the first indication information to the user plane function network element.

11. The method according to claim 9 or 10, characterized in that, Before receiving the fifth indication information, the method further includes: Send second indication information to the user plane function network element, where the second indication information is used to indicate providing the function of the transmission proxy for the first session.

12. The method according to claim 11, wherein The sending the second indication information to the user plane function network element includes: Based on the sixth indication information, send the second indication information to the user plane function network element.

13. The method according to claim 11, characterized in that Before sending the second indication information to the user plane function network element, the method further includes: Receive seventh indication information, where the seventh indication information is used to indicate that the terminal supports the path switching of the first session or the terminal supports path switching; The sending the second indication information to the user plane function network element includes: Based on the seventh indication information, send the second indication information to the user plane function network element.

14. The method according to claim 11, wherein Before sending the second indication information to the user plane function network element, the method further includes: Receive eighth indication information, where the eighth indication information is used to indicate supporting the service continuity during the path switching of the first session; The sending the second indication information to the user plane function network element includes: Based on the eighth indication information, send the second indication information to the user plane function network element.

15. The method according to any one of claims 11 to 14, characterized in that, After sending the second indication information to the user plane function network element, the method further includes: Send ninth indication information to the terminal, where the ninth indication information is used to indicate that the first session has the function of the transmission proxy or the first session supports path switching.

16. The method according to any one of claims 7 to 15, characterized in that, After sending the first indication information to the user plane function network element, the method further includes: Send fourth indication information to the user plane function network element, where the fourth indication information is used to indicate to start the downlink data transmission of the first session.

17. A communication method, characterized in that, Includes: Receive ninth indication information, where the ninth indication information is used to indicate that a first session of the terminal has the function of a transmission proxy or the first session supports path switching, the transmission proxy being a Transmission Control Protocol connection transmission proxy, or, the transmission proxy being a Quick User Datagram Protocol network connection transmission proxy; Based on the ninth indication information, send fifth indication information, where the fifth indication information is used to indicate to switch the path for the first session of the terminal.

18. The method according to claim 17, wherein The sending of the fifth indication information includes: Send the fifth indication information through a first radio access network node, where the first radio access network node is a radio access network node that is used to transmit data of the first session before the path switching of the first session.

19. The method according to claim 17, wherein The sending of the fifth indication information includes: Send the fifth indication information through a second radio access network node, where the second radio access network node is a radio access network node that is used to transmit data of the first session after the path switching of the first session.

20. The method according to any one of claims 17 to 19, characterized in that, The method further includes: Send sixth indication information, where the sixth indication information is used to indicate that the terminal does not support transmitting data with a first radio access network node during the path switching of the first session, and the first radio access network node is a radio access network node that is used to transmit data of the first session before the path switching of the first session.

21. The method according to any one of claims 17 to 20, characterized in that, Before the receiving of the ninth indication information, the method further includes: Send seventh indication information, where the seventh indication information is used to indicate that the terminal supports the path switching of the first session or the terminal supports path switching.

22. A communication device, characterized in that, Include a module for implementing the method according to any one of claims 1 to 6, or, a module for implementing the method according to any one of claims 7 to 16, or, a module for implementing the method according to any one of claims 17 to 21.

23. A communication device, characterized in that, Include a processor, where the processor is coupled to a memory, and the memory is used to store programs or instructions. When the programs or instructions are executed by the processor, the method according to any one of claims 1 to 6 is executed, or, the method according to any one of claims 7 to 16 is executed, or, the method according to any one of claims 17 to 21 is executed.

24. A computer-readable storage medium, characterized in that, For storing a computer program, when the computer program runs on a computer, the method according to any one of claims 1 to 6 is executed, or, the method according to any one of claims 7 to 16 is executed, or, the method according to any one of claims 17 to 21 is executed.

25. A computer program product, characterized in that, Include: A computer program or instructions, when the computer program or instructions are run, the method according to any one of claims 1 to 6 is executed, or, the method according to any one of claims 7 to 16 is executed, or, the method according to any one of claims 17 to 21 is executed.

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