Communication method and apparatus

Abstract

A communication method and apparatus, which relate to the technical field of wireless communications. The method comprises: a first SMF sending address information of a mobile node to the mobile node, wherein the address information of the mobile node is public network address information, the address information of the mobile node is used for establishing a user plane tunnel between the mobile node and a first user plane function (UPF), the user plane tunnel belongs to a first session between the first UPF and a terminal device which accesses the mobile node, the first UPF is a UPF serving the terminal device, and the mobile node is used for providing an access service for the terminal device.

Description

Communication method and device

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office of the People's Republic of China on April 3, 2024, with application number 202410406988.5 and invention name "A Communication Method and Device", the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present application relates to the field of mobile communication technologies, and in particular to a communication method and device. Background Art

[0004] Currently, mobile gNBs with wireless access backhaul (MWAB) are being proposed for vehicular scenarios. MWAB equipment can be deployed on a moving vehicle and consists of a base station (MWAB-gNB) and a terminal (MWAB-UE).

[0005] Because vehicles move, MWAB-gNB and MWAB-UE also have mobility. Among them, MWAB-UE has the functions of ordinary terminal equipment and can access the core network through new radio (NR). Usually, the next generation application protocol (NG Application Protocol, NGAP) backhaul link between the fixed wireless access network equipment on the ground and the core network can be implemented through optical fiber. The NGAP backhaul link between the mobile MWAB-gNB and the core network can be implemented by the protocol data unit (PDU) session between the MWAB-UE and the core network. In this way, the MWAB-gNB can provide wireless access services to other terminal devices near the vehicle.

[0006] Currently, the core network assigned to a MWAB-UE by the MWAB-UE is a private IP address, and this private IP address is sent as network tunnel information to the user plane function (UPF) serving the terminal device (which accesses the MWAB-gNB). During the transmission of uplink General Packet Radio Service (GPRS) tunneling protocol-user plane (GTP-U) messages, the MWAB-UE's private IP address in the uplink GTP-U messages is converted to a public IP address. This public IP address of the MWAB-UE is inconsistent with the private IP address stored by the UPF, which can affect service transmission for the terminal device. Summary of the Invention

[0007] The embodiments of the present application provide a communication method and apparatus to solve the current problem of address allocation for mobile nodes.

[0008] In a first aspect, a communication method is provided. The method can be applied to a first session management function (SMF), the method comprising: sending address information of the mobile node to a mobile node, where the address information of the mobile node is public network address information. The address information of the mobile node is used to establish a user plane tunnel between the mobile node and a first UPF, where the user plane tunnel belongs to a first session between a terminal device accessing the mobile node and the first UPF, where the first UPF is a UPF serving the terminal device, and the mobile node is configured to provide access services for the terminal device.

[0009] In the above implementation, since the address information assigned to the mobile node by the core network to which the mobile node is registered is public network address information, during the uplink transmission process, when the uplink message is sent to the UPF providing services for the terminal device, the UPF can match the source address information in the uplink message (i.e., the public network address information of the mobile node) to the public network address information in the tunnel information it stores, that is, it can match the corresponding user plane tunnel, thereby ensuring the service transmission of the terminal device.

[0010] In a possible implementation, the method further includes: receiving a first request message; the first request message is used to request modification of a second session, where the second session is used to establish a first backhaul link before modification, and the second session is used to establish a second backhaul link after modification; or the first request message is used to request establishment of a third session, where the third session is used to establish the second backhaul link. The first backhaul link is a backhaul link between the mobile node and a first access and mobility management function (AMF), the second backhaul link is a backhaul link between the mobile node and the first UPF, and the first AMF serves the terminal device.

[0011] In a possible implementation manner, the method further includes: sending a first response message in response to the first request message, where the first response message includes the address information of the mobile node.

[0012] In a possible implementation, the first request message includes indication information for indicating a type of the third session, where the indication information indicates that the type of the third session is a session for establishing the second backhaul link.

[0013] In a possible implementation, the public network address information is allocated by the first SMF to the mobile node.

[0014] In one possible implementation, before sending the address information of the mobile node to the mobile node, it also includes: sending a second request message to the second UPF, the second request message including first indication information, the first indication information instructing the second UPF to allocate public network address information to the mobile node, or instructing the first UPF to allocate private network address information to the mobile node and determine the public network address information corresponding to the private network address information; receiving a second response message from the second UPF, the second response message including the public network address information.

[0015] In one possible implementation, before sending the address information of the mobile node to the mobile node, it also includes: sending a second request message to the second UPF, the second request message including the private network address information allocated by the first SMF to the mobile node and second indication information, the second indication information instructing the second UPF to determine the public network address information corresponding to the private network address information; receiving a second response message from the second UPF, the second response message including the public network address information.

[0016] In one possible implementation, the first request message also includes the address information of the first UPF, or the first request message and the second request message also include the address information of the first UPF; the public network address information is determined based on the address information of the first UPF.

[0017] In one possible implementation, after receiving the first request message, it also includes: determining to allocate public network address information to the mobile node based on one or more of the following: the subscription information of the mobile node; or the type of the third session; or the data network name (DNN) and / or single network slice selection assistance information (S-NSSAI) associated with the second session or the third session.

[0018] In the second aspect, a communication method is provided, which is applied to a mobile node, and the method includes: receiving address information assigned to the mobile node from a first SMF, the address information of the mobile node being public network address information; wherein the address information of the mobile node is used to establish a user plane tunnel between the mobile node and a first UPF, the user plane tunnel belongs to a first session between a terminal device accessing the mobile node and the first UPF, the first UPF is a UPF serving the terminal device, and the mobile node is used to provide access services for the terminal device; sending the public network address information to the first UPF.

[0019] In a possible implementation, it also includes: sending a first request message to the first SMF; wherein the first request message is used to request modification of the second session, and the second session is used to establish a first backhaul link before modification, and the second session is used to establish a second backhaul link after modification; or, the first request message is used to request establishment of a third session, and the third session is used to establish the second backhaul link; wherein the first backhaul link is a backhaul link between the mobile node and the first AMF, the second backhaul link is a backhaul link between the mobile node and the first UPF, and the first AMF serves the terminal device.

[0020] In a possible implementation, the first request message includes indication information for indicating a type of the third session, where the indication information indicates that the type of the third session is a session for establishing the second backhaul link.

[0021] In a possible implementation, the first request message includes the address information of the first UPF, and the public network address information is determined based on the address information of the first UPF.

[0022] In a possible implementation, the receiving, from the first SMF, the address information allocated to the mobile node includes: receiving, from the first SMF, a first response message in response to the first request message, wherein the first response message includes the address information of the mobile node.

[0023] According to a third aspect, a communication method is provided, which is applied to a mobile node, and the method includes: in the process of establishing a first session, receiving address information assigned to the mobile node from a first SMF; wherein, the first session is a session of a terminal device accessing the mobile node, and the mobile node is used to provide access services for the terminal device; sending tunnel information and indication information to the first UPF, the tunnel information including the address information of the mobile node and a first tunnel endpoint identification (TEID), and the indication information instructs the first UPF to determine the user plane tunnel according to the TEID in the uplink message; wherein, the first UPF is the UPF serving the terminal device.

[0024] In the above implementation method, since the mobile node instructs the first UPF to use the TEID in the uplink message to match the user plane tunnel through the indication information, the UPF can match the corresponding user plane tunnel according to the first TEID in the uplink message, determine which base station the uplink message comes from, and thus ensure the service transmission of the terminal device.

[0025] In one possible implementation, before receiving the address information assigned to the mobile node from the first SMF, it also includes: sending a first request message to the first SMF, the first request message is used to obtain the address information of the mobile node, the address information of the mobile node is used to establish a user plane tunnel between the mobile node and the first UPF, and the user plane tunnel belongs to the first session.

[0026] In one possible implementation, before sending the first request message to the first SMF, it also includes: receiving the address information and the second TEID of the first UPF; sending tunnel information and indication information to the first UPF includes: sending a user plane message to the first UPF according to the address information of the first UPF and the second TEID, and the user plane message includes the tunnel information and the indication information.

[0027] In a possible implementation manner, the first TEID is allocated by the mobile node.

[0028] In a fourth aspect, a communication method is provided, which is applied to a first UPF, wherein the first UPF is the UPF of a terminal device serving an access mobile node, and the method includes: receiving tunnel information and indication information from the mobile node, the tunnel information including the address information and the first TEID of the mobile node; when an uplink message is received, determining the user plane tunnel corresponding to the first TEID in the uplink message based on the indication information and the tunnel information in the uplink message.

[0029] In the fifth aspect, a communication method is provided, which is applied to a first UPF, and the method includes: receiving a first uplink message from a mobile node, the first uplink message indicating the correspondence between the private network address information and the public network address information of the mobile node; when a second uplink message from the mobile node is received, determining the private network address information corresponding to the source address information according to the source address information in the second uplink message and the correspondence, and determining the corresponding user plane tunnel according to the private network address information; wherein, the source address information is the public network address information of the mobile node.

[0030] In the above implementation, the mobile node sends the correspondence between the private network address information and the public network address information of the mobile node to the first UPF via a first uplink message. During the uplink transmission process, when a second uplink message is sent to the UPF providing services for the terminal device, even if the source address information in the second uplink message is converted into public network address information by the second UPF, the first UPF can still determine the private network address information of the mobile node based on the correspondence, and thus can match the private network address information with the private network address information in the tunnel information stored by it, that is, can match it with the corresponding user plane tunnel, thereby ensuring service transmission of the terminal device.

[0031] In one possible implementation, the message header of the first uplink message includes the private network address information of the mobile node, and the payload of the first uplink message includes source address information, which is converted from the private network address information of the mobile node to public network address information.

[0032] In one possible implementation, before receiving the first uplink message from the mobile node, it also includes: receiving tunnel information from the mobile node, the tunnel information includes the address information of the mobile node, the address information of the mobile node is private network address information, the tunnel information is used to establish a user plane tunnel between the mobile node and the first UPF, the user plane tunnel belongs to the first session between the terminal device accessing the mobile node and the first UPF, the first UPF is the UPF serving the terminal device, and the mobile node is used to provide access services for the terminal device; determining the corresponding user plane tunnel based on the private network address information includes: determining the corresponding user plane tunnel based on the private network address information and the tunnel information.

[0033] In a sixth aspect, a communication method is provided, which is applied to a mobile node, and the method includes: sending a first uplink message to a first UPF, wherein the first uplink message indicates the correspondence between the private network address information and the public network address information of the mobile node.

[0034] In one possible implementation, the message header of the first uplink message includes the private network address information of the mobile node, and the payload of the first uplink message includes source address information, which is converted from the private network address information of the mobile node to public network address information.

[0035] In one possible implementation, before sending the first uplink message to the first UPF, it also includes: sending tunnel information to the first UPF, the tunnel information including the address information of the mobile node, the address information of the mobile node is private network address information, the tunnel information is used to establish a user plane tunnel between the mobile node and the first UPF, the user plane tunnel belongs to the first session between the terminal device accessing the mobile node and the first UPF, the first UPF is the UPF serving the terminal device, and the mobile node is used to provide access services for the terminal device.

[0036] In the seventh aspect, a communication method is provided, which is applied to a mobile node, and the method includes: receiving address information allocated to the mobile node from a first SMF, and the address information is private network address information; sending a request message to a server for providing public network address information service after address conversion, and the request message is used to obtain the public network address information after the private network address of the mobile node is converted; receiving a response message from the server, and the response message includes the public network address information; sending tunnel information to a first UPF, and the tunnel information includes the public network address information, and the tunnel information is used to establish a user plane tunnel between the mobile node and the first UPF, and the user plane tunnel belongs to the first session between the terminal device accessing the mobile node and the first UPF, the first UPF is the UPF serving the terminal device, and the mobile node is used to provide access services for the terminal device.

[0037] In the above implementation method, after the mobile node obtains the public network address information corresponding to the private network address information assigned to it, it sends it to the first UPF as tunnel information, so that during the uplink transmission process, when the uplink message is sent to the UPF providing services for the terminal device, the UPF can match the source address information in the uplink message (i.e., the public network address information of the mobile node) to the public network address information in the tunnel information it stores, that is, it can match the corresponding user plane tunnel, thereby ensuring the service transmission of the terminal device.

[0038] In a possible implementation, the mobile node is configured as a STUN (simple traversal of UDP over NATs) client, and the server is configured as a STUN server.

[0039] In the eighth aspect, a communication device is provided, comprising a unit or module for executing the method as described in any one of the first aspect, or a unit or module for executing the method as described in any one of the second aspect, or a unit or module for executing the method as described in any one of the third aspect, or a unit or module for executing the method as described in the fourth aspect, or a unit or module for executing the method as described in any one of the fifth aspect, or a unit or module for executing the method as described in any one of the sixth aspect, or a unit or module for executing the method as described in any one of the seventh aspect.

[0040] In the ninth aspect, a communication device is provided, comprising: one or more processors configured to execute the method as described in any one of the first aspect, or execute the method as described in any one of the second aspect, or execute the method as described in any one of the third aspect, or execute the method as described in any one of the fourth aspect, or execute the method as described in any one of the fifth aspect, or execute the method as described in any one of the sixth aspect, or execute the method as described in any one of the seventh aspect.

[0041] In the tenth aspect, a readable storage medium is provided, which stores a program or instruction. When the program or instruction is run on a device, the device executes the method as described in any one of the first aspect, or executes the method as described in any one of the second aspect, or executes the method as described in any one of the third aspect, or executes the method as described in any one of the fourth aspect, or executes the method as described in any one of the fifth aspect, or executes the method as described in any one of the sixth aspect, or executes the method as described in any one of the seventh aspect.

[0042] In the eleventh aspect, a chip is further provided, which is used to read a computer program stored in a memory and execute the method provided in the first aspect. Optionally, the chip may include a processor, which is coupled to the memory and is used to read the computer program stored in the memory to implement the method provided in the above embodiment. Optionally, the chip may also include components such as a memory, a communication interface, and a power supply module. The memory is used to store computer programs, the communication interface is used to receive and send data, and the power supply unit is used to power the processor.

[0043] In the twelfth aspect, a chip system is provided, comprising a processor for supporting a computer device to implement the method as described in any one of the first aspect, or the method as described in any one of the second aspect, or the method as described in any one of the third aspect, or the method as described in any one of the fourth aspect, or the method as described in any one of the fifth aspect, or the method as described in any one of the sixth aspect, or the method as described in any one of the seventh aspect.

[0044] In the thirteenth aspect, a program product is provided, comprising a computer program. When the program is executed by a processor, the program implements the method described in any one of the first aspect, or the method described in any one of the second aspect, or the method described in any one of the third aspect, or the method described in any one of the fourth aspect, or the method described in any one of the fifth aspect, or the method described in any one of the sixth aspect, or the method described in any one of the seventh aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] FIG1 is a schematic diagram of a 5G network architecture based on a service-oriented interface applicable to an embodiment of the present application;

[0046] FIG2 is a schematic diagram of a 5G network architecture based on a point-to-point interface applicable to an embodiment of the present application;

[0047] FIG3 is a schematic diagram of the basic architecture of the MWAB device in an embodiment of the present application;

[0048] FIG4 is a flow chart of a communication method provided in an embodiment of the present application;

[0049] FIG5 is a schematic diagram of an example process based on FIG4 in an embodiment of the present application;

[0050] FIG6 is a schematic diagram of another example process based on FIG4 in an embodiment of the present application;

[0051] FIG7 is a schematic diagram of another example process based on FIG4 in an embodiment of the present application;

[0052] FIG8 is a flow chart of another communication method provided in an embodiment of the present application;

[0053] FIG9 is a schematic diagram of an example process based on FIG8 in an embodiment of the present application;

[0054] FIG10 is a flow chart of another communication method provided in an embodiment of the present application;

[0055] FIG11 is a flow chart of another communication method provided in an embodiment of the present application;

[0056] FIG12 is a schematic structural diagram of a communication device provided in an embodiment of the present application;

[0057] FIG13 is a schematic structural diagram of another communication device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0058] The 3GPP standards group has developed the architecture for the next-generation mobile communications network system (NGS), known as the 5G network architecture. This architecture supports access to the 5G core network (CN) using radio access technologies defined by the 3GPP standards group, such as long-term evolution (LTE) and 5G radio access network (RAN). It also supports access to the core network using non-3GPP access technologies via the non-3GPP interworking function (N3IWF) or the next-generation packet data gateway (ngPDG).

[0059] Figure 1 is a schematic diagram of a 5G network architecture based on a service-oriented architecture. The 5G network architecture shown in Figure 1 includes access network equipment and core network equipment. Terminal devices access the data network (DN) through the access network equipment and core network equipment. Among them, the core network equipment includes but is not limited to some or all of the following network elements: authentication server function (AUSF) network element, unified data management (UDM) network element, unified data repository (UDR) network element (not shown in the figure), network storage function (NRF) network element, network exposure function (NEF) network element, network slice selection function (NSSF) network element, network slice selection authentication and authorization function (NSSAAF) network element, network slice admission control function (NSACF) network element, application function (AF) network element, policy control function (PCF) network element, access and mobility management function (AMF) network element, session management function (SMF) network element, UPF network element, binding support function (BSF) network element (not shown in the figure).

[0060] Terminal devices can be user equipment (UE), mobile stations, mobile terminal devices, etc. Terminal devices can be widely used in various scenarios, such as device-to-device (D2D), vehicle-to-everything (V2X) communication, machine-type communication (MTC), Internet of Things (IoT), virtual reality, augmented reality, industrial control, autonomous driving, telemedicine, smart grid, smart furniture, smart office, smart wearables, smart transportation, smart cities, etc. Terminal devices can be mobile phones, tablets, computers with wireless transceiver functions, wearable devices, vehicles, urban air vehicles (such as drones and helicopters), ships, robots, robotic arms, smart home devices, etc.

[0061] The access network device is a device with wireless transceiver functions, which is used to communicate with the terminal device. The access network device includes but is not limited to base stations (base transceiver station (BTS), Node B, eNodeB / eNB, or gNodeB / gNB), transmission reception points (TRP), base stations subsequently evolved from the third generation partnership project (3GPP), access nodes in Wi-Fi systems, wireless relay nodes, wireless backhaul nodes, etc. The base station can be: a macro base station, a micro base station, a pico base station, a small station, a relay station, etc. Multiple base stations can support networks with the same access technology or networks with different access technologies. The base station can include one or more co-site or non-co-site transmission and receiving points. The access network device can also be a wireless controller, a centralized unit (CU), and / or a distributed unit (DU) in a cloud radio access network (CRAN) scenario. The access network device can also be a server, etc.

[0062] Access network equipment and terminal devices can be fixed or mobile. They can be deployed on land, including indoors or outdoors, handheld or vehicle-mounted; on water; or in the air on aircraft, balloons, and satellites. The embodiments of this application do not limit the application scenarios of access network equipment and terminal devices.

[0063] The AMF network element is responsible for UE mobility management, including mobile state management, allocating temporary identities to UEs, and authenticating and authorizing UEs.

[0064] The SMF network element is responsible for the selection and reselection of UPF network elements, IP address allocation, bearer establishment, modification and release, and quality of service (QoS) control.

[0065] The UPF network element supports all or part of the following functions: interconnecting protocol data unit (PDU) sessions with the data network; packet routing and forwarding (for example, supporting uplink classification of traffic before forwarding to the data network); and packet inspection.

[0066] The UDM network element is responsible for managing contract data and notifying the corresponding network element when the contract data is modified.

[0067] In Figure 1, Nnssf, Nnef, Nnrf, Npcf, Nudm, Naf, Nnssaaf, Nausf, Namf, Nsmf, and Nnsacf are service-oriented interfaces provided by the NSSF, NEF, NRF, PCF, UDM, AF, NSSAAF, AUSF, AMF, SMF, and NSACF, respectively, and are used to invoke corresponding service-oriented operations. N1, N2, N3, N4, N6, and N9 are interface serial numbers, and their meanings are as follows:

[0068] N1: The interface between AMF and terminal devices, which can be used to deliver non-access stratum (NAS) signaling (such as QoS rules from AMF) to terminal devices.

[0069] N2: The interface between AMF and access network equipment, which can be used to transmit radio bearer control information from the core network side to the access network equipment.

[0070] N3: The interface between the access network equipment and UPF, mainly used to transmit uplink and downlink user plane data between the access network equipment and UPF.

[0071] N4: The interface between SMF and UPF can be used to transmit information between the control plane and the user plane, including controlling the issuance of forwarding rules, QoS rules, traffic statistics rules, etc. for the user plane and reporting information to the user plane.

[0072] N6: Interface between UPF and DN, used to transmit uplink and downlink user data flows between UPF and DN.

[0073] N9: User plane interface between UPF network elements, used to transmit uplink and downlink user data flows between UPF network elements.

[0074] Figure 2 is a schematic diagram of a 5G network architecture based on point-to-point interfaces. The functions of the network elements in Figure 2 can be referred to as those of the corresponding network elements in Figure 1 and will not be repeated here. The main difference between Figure 2 and Figure 1 is that the interfaces between the control plane network elements in Figure 1 are service-oriented interfaces, while the interfaces between the control plane network elements in Figure 2 are point-to-point interfaces.

[0075] It is understood that the above-mentioned network element or function can be a network element in a hardware device, a software function running on dedicated hardware, or a virtualized function instantiated on a platform (e.g., a cloud platform). Optionally, the above-mentioned network element or function can be implemented by a single device, or by multiple devices, or can be a functional module within a single device, and this is not specifically limited in the embodiments of the present application.

[0076] The mobility management network element, session management network element, data management network element, and network storage function network element in this application can be the AMF network element, SMF network element, UDM network element, and NRF network element in the 5G system, respectively, or can be a network element in the future communication network that has the functions of the above-mentioned AMF network element, SMF network element, UDM network element, and NRF network element. This application is not limited to this. In the embodiments of this application, an example is described in which the AMF network element, SMF network element, UDM network element, and NRF network element are the mobility management network element, session management network element, data management network element, and network storage function network element, respectively. In addition, the AMF network element, SMF network element, UDM network element, and NRF network element are referred to as AMF, SMF, UDM, and NRF, respectively.

[0077] For ease of explanation, the embodiments of the present application are described using a base station and a UE as specific examples of an access network device and a terminal device, respectively. Any base station and UE appearing in any subsequent location can be replaced by an access network device and a terminal device, respectively.

[0078] Currently, MWAB devices are being proposed for in-vehicle scenarios. MWAB devices are typically deployed on moving vehicles. An MWAB device consists of a base station and a user equipment (UE). The UE can be referred to as an MWAB-UE, and the base station can be referred to as an MWAB-gNB. Because vehicles move, the MWAB-gNB and MWAB-UE also exhibit mobility. The MWAB-UE functions as a standard terminal device and can access the core network via NR. Typically, the N2 backhaul link between a fixed ground base station and the core network can be implemented using optical fiber. However, the N2 backhaul link between the mobile MWAB-gNB and the core network can be carried over the PDU session between the MWAB-UE and the core network to achieve wireless backhaul. This allows the MWAB-gNB to provide wireless access to other terminal devices near the vehicle. MWAB devices can also be referred to as wireless access and backhaul (WAB) devices. The UEs that comprise the WAB can be referred to as WAB-UEs, and the base stations that comprise the WAB can be referred to as WAB-gNBs. Alternatively, the MWAB device can also be called a vehicle mounted relay (VMR) device, the UE that constitutes the VMR can be called a VMR-UE, and the base station that constitutes the VMR can be called a VMR-gNB.

[0079] Figure 3 shows a schematic diagram of the basic architecture of a MWAB device. A MWAB-UE accesses the core network via a base station (e.g., a donor-gNB) located outside the vehicle and establishes a PDU session between the MWAB-UE and the UPF (UPF#1 in the figure). The donor-gNB is also called a macro base station. N2 messaging between the MWAB-gNB and the AMF (AMF#2 in the figure) is implemented via a PDU session between the MWAB-UE and the UPF. For example, when the MWAB-gNB needs to send an N2 message to AMF#2, the MWAB-gNB forwards the N2 message to the MWAB-UE via the internal interface between the MWAB-gNB and the MWAB-UE. The MWAB-UE then uses the N2 message as the payload of a data packet and passes it to the anchor UPF (UPF#1 in the figure) via the established PDU session. The anchor UPF then forwards the data packet to AMF#2, completing the N2 message forwarding. The N3 message transmission between the MWAB-gNB and the UPF (such as UPF#2 in the figure) can also be implemented through the PDU session between the MWAB-UE and the UPF. For example, when the MWAB-gNB needs to send an N3 message to UPF#2, the MWAB-gNB forwards the N3 message to the MWAB-UE through the internal interface between the MWAB-UE and the MWAB-UE. The MWAB-UE uses the N3 message as the payload of the data packet and passes it to the anchor UPF of the PDU session (which can be UPF#1 in the figure or other UPF, not limited in this application) through the established PDU session. The anchor UPF then forwards the data packet to UPF#2, thereby completing the forwarding of the N3 message.

[0080] Based on the architecture of the MWAB device shown in FIG3 , the public land mobile network (PLMN) registered by the MWAB-UE and the PLMN registered by the normal UE can be different PLMNs or the same PLMN.

[0081] Taking the architecture shown in Figure 3 as an example, the core network to which the MWAB-UE accesses currently allocates a private IP address to the MWAB-UE, and the MWAB-UE sends the private IP address as tunnel information to UPF#2, which provides services for the UE. During uplink transmission, the MWAB encapsulates the uplink data message from the UE into a GTP-U message and sends the GTP-U message to UPF#1 (i.e., the anchor point UPF for the PDU session between the MWAB-UE and UPF#1). UPF#1 converts the private IP address of the MWAB-UE in the GTP-U message into a public IP address and sends the GTP-U message after the address conversion to UPF#2. After receiving the GTP-U message, UPF#2 needs to match the user plane tunnel based on the IP address of the MWAB-UE and the tunnel information in the GTP-U message. However, since the IP address of the MWAB-UE in the GTP-U message is a public IP address, and the IP address of the MWAB-UE in the tunnel information is a private IP address, UPF#2 cannot match the corresponding user plane tunnel based on the IP address of the MWAB-UE in the GTP-U message, that is, it is impossible to determine which base station the GTP-U message comes from, which will affect the UE's service transmission.

[0082] In order to solve the problems caused by the current MWAB address allocation method, the embodiments of the present application provide a communication method and related devices that can implement the method.

[0083] First, the technologies and technical terms involved in this application are explained below.

[0084] (1) Mobile Node

[0085] The mobile node in the embodiment of the present application has a terminal function and a base station function. The mobile node can be composed of a terminal and a base station. The terminal can be referred to as a mobile node-terminal or a mobile node-UE, and the base station can be referred to as a mobile node-base station or a mobile node-gNB. The mobile node-terminal has the functions of an ordinary terminal device and can access the core network through a radio access network device. The mobile node-base station can provide network access services for ordinary terminal devices, and the connection between the ordinary terminal device and the core network (such as an N2 connection or an N3 connection) can be realized through a session between the mobile node-terminal and the core network.

[0086] An example of the mobile node may be a MWAB device, and accordingly, the mobile node-terminal is a MWAB-UE, and the mobile node-base station is a MWAB-gNB.

[0087] (2) First backhaul link and second backhaul link

[0088] In embodiments of the present application, a mobile node-base station can provide wireless access services to surrounding terminal devices, and the terminal devices can access the core network through the mobile node-base station. A connection can be established between the mobile node-base station and the core network to carry signaling and / or data transmission between the terminal devices accessed through the mobile node-base station and the core network.

[0089] A first backhaul link can be established between the mobile node-base station and the core network accessed by the terminal device. The first backhaul link, also known as an N2 connection or NGAP connection, is the connection between the mobile node-base station and the AMF accessed by the terminal device, or in other words, an N2 interface exists between the mobile node-base station and the AMF. The first backhaul link can carry signaling between the terminal device accessed through the mobile node-base station and the core network.

[0090] A second backhaul link can also be established between the mobile node-base station and the core network accessed by the terminal device. This second backhaul link, also known as an N3 connection, is the connection between the mobile node-base station and the UPF accessed by the terminal device, or in other words, an N3 interface exists between the mobile node-base station and the UPF. This second backhaul link can carry data transmission between the terminal device accessed through the mobile node-base station and the core network.

[0091] (3) First session, second session, and third session

[0092] In an embodiment of the present application, a terminal device may access a network through a mobile node. A terminal device that accesses a core network through a mobile node may establish a first session through the mobile node. Specifically, the first session may transmit uplink and downlink services through a user plane tunnel established between the mobile node and the UPF.

[0093] In an embodiment of the present application, a mobile node-terminal may register with the core network as a terminal device. For example, a MWAB-UE may register with the AMF as a normal UE. A session may be established between the mobile node-terminal and the core network in which it is registered. This session may be a session between the mobile node-terminal and the UPF, where the UPF may be referred to as the anchor UPF for the session. Taking the 5G core network as an example, this session may be a PDU session.

[0094] The session between the mobile node-terminal and the core network may be used to establish the first backhaul link and / or the second backhaul link.

[0095] In an embodiment of the present application, the session established between the mobile node-terminal and the core network may include a second session, and the second session is used to establish the above-mentioned first backhaul link. It can also be understood that the second session is used for wireless backhaul of the first backhaul link. Taking the second session as the second PDU session as an example, the second PDU session is used for wireless backhaul of the N2 connection (PDU session for wireless backhauling of the N2). Alternatively, it can also be understood that the second session is used to carry the above-mentioned first backhaul link. Alternatively, the second session can be called: PDU session for Wireless backhauling, or PDU session for wireless backhauling of the N2.

[0096] In an embodiment of the present application, the session established between the mobile node-terminal and the core network may include a third session, and the third session is used to establish the above-mentioned second backhaul link. It can also be understood that the third session is used for wireless backhaul of the second backhaul link. Taking the third session as the third PDU session as an example, the third PDU session is used for wireless backhaul of the N3 connection (PDU session for wireless backhauling of the N3). Alternatively, it can also be understood that the third session is used to carry the above-mentioned second backhaul link. Alternatively, the third session can be called: PDU session for Wireless backhauling, or PDU session for wireless backhauling of the N3.

[0097] The anchor point UPF of the second session and the anchor point UPF of the third session may be the same or different.

[0098] (4) Public network address and private network address

[0099] Public and private IP addresses are two different types of IP addresses, distinguished by their network scope and usage. Public addresses, also known as globally unique IP addresses, are IP addresses that can be directly accessed on the Internet. These addresses are assigned by Internet registries and are globally unique and globally reachable. Public addresses are commonly used for servers, routers, and other network devices on the Internet. They can directly access other devices on the Internet and facilitate communication and data transmission over the Internet. Private addresses, also known as local area network (LAN) IP addresses, are IP addresses used within a local area network (LAN). They are not globally unique or globally reachable and can only be used within a LAN.

[0100] Private network addresses are typically used to establish local area networks (LANs), such as home networks, corporate intranets, and campus networks. Within a LAN, devices can communicate and transmit data using private network addresses. However, to access other devices on the Internet, data forwarding through a router is required.

[0101] The differences between public and private network addresses are mainly reflected in the following aspects:

[0102] First: The allocation methods are different. Public network addresses are allocated by Internet registration agencies, while private network addresses are allocated by local area network administrators.

[0103] The second aspect: the scope of use is different. Public network addresses are used for devices on the Internet, and private network addresses are used for devices within the local area network.

[0104] The third aspect: Uniqueness and reachability are different. Public network addresses are globally unique and globally reachable, while private network addresses are only unique within the local area network and are not globally reachable.

[0105] Fourth aspect: The forwarding methods are different. Public network addresses can directly access other devices on the Internet, while private network addresses need to be forwarded through a router to access other devices on the Internet.

[0106] Currently, there are three classes of private network addresses: Class A, Class B, and Class C. These address ranges are private and can be used within a local area network (LAN) but are not routable on the Internet. Their ranges are as follows:

[0107] Class A address: 10.0.0.0-10.255.255.255, where 10.0.0.0 is the network address and 10.255.255.255 is the broadcast address.

[0108] Class B address: 172.16.0.0-172.31.255.255, where 172.16.0.0 is the network address and 172.31.255.255 is the broadcast address.

[0109] Class C address: 192.168.0.0-192.168.255.255, where 192.168.0.0 is the network address and 192.168.255.255 is the broadcast address.

[0110] (5) Network Address Translation (NAT)

[0111] When using private network addresses within a LAN, it's sometimes necessary to access other devices on the Internet. This is where NAT technology comes in handy. NAT, also known as address proxy, translates internal private network addresses (private network addresses) into public network addresses (public network addresses) that can be used on the public network. This effectively hides the IP addresses of hosts on the LAN, providing security. In practice, NAT is primarily used to connect private networks to external networks, or vice versa.

[0112] STUN (simple traversal of UDP over NATs) is a network protocol that provides a simple way for the User Datagram Protocol (UDP) to traverse NATs. It is used to establish UDP communication between hosts behind NAT routers. It allows applications to discover the presence and type of NAT between them and the public internet, and also allows applications to obtain the public IP address and port number assigned by the NAT. STUN is a client / server and request / response protocol, with the default port number being 3478.

[0113] STUN works as follows: A STUN client sends a UDP request to a STUN server outside the NAT. After receiving the request, the STUN server returns the STUN client's external IP address and port information to the STUN client via UDP. Simultaneously, the STUN protocol establishes a dynamic mapping on the NAT, allowing the STUN server to connect back to the STUN client, thus achieving NAT traversal.

[0114] For example, client A sends a Binding request to the STUN port. After receiving the Binding request, the STUN server obtains the source address and source port of the request (the source address and source port are mapped by NAT), and records the source address and source port as the Server Reflexive Address. The STUN server fills the Server Reflexive Address into the XOR-MAPPED-ADDRESS attribute after XORing it, and carries it in the Response message. After receiving the response from the STUN server, client A obtains the Server Reflexive Address. In the above process, when the Binding request passes through the NAT gateway, the NAT gateway performs NAT on the source address of the request, that is, the Server Reflexive Address is the address mapped by the NAT gateway.

[0115] The STUN standard categorizes NAT into four types based on how private IP addresses and ports are mapped to the public IP addresses and ports at the NAT egress: Full Cone NAT, Restricted Cone NAT, Port Restricted Cone NAT, and Symmetric NAT.

[0116] Full Cone NAT: All requests sent from the same private IP address and port (IP1:Port1) are mapped to the same public IP address and port (IP:Port). Furthermore, any external host can communicate with internal hosts by sending packets to the mapped public IP address and port. This is a relatively relaxed policy; as long as a mapping between private IP addresses and ports and public IP addresses and ports is established, any host on the Internet can access the host behind NAT.

[0117] Restricted Cone NAT: All requests from the same private IP address and port (IP1:Port1) are mapped to the same public IP address and port (IP:Port). Unlike Full Cone NAT, a public host can send a message to a private host only if the private host has previously sent a message to the public host.

[0118] Port-restricted cone NAT: Similar to restricted cone NAT, except that it includes port numbers. This means that a public network host (IP2:Port2) can only send packets to the corresponding private network relay if it has already sent packets to that IP address and port.

[0119] Symmetric NAT: All requests sent from the same private IP address and port to a specific destination IP address and port are mapped to the same IP address and port. If the same host sends a packet using the same source address and port number but to different destinations, NAT will perform different mappings. Furthermore, only the public host that received the data can send packets back to the private host. This differs from port-restricted cone NAT, which maps all requests to the same public IP address and port. Symmetric NAT uses different mappings for different requests.

[0120] The method provided in the embodiments of the present application is described below with reference to the accompanying drawings.

[0121] Refer to Figure 4, which is a flow chart of a communication method provided in an embodiment of the present application. In this method, the mobile node has registered with the core network, and the core network includes a second AMF, a first SMF, and a second UPF. A second session is established between the mobile node and the second UPF in the core network. The terminal device accesses the network through the mobile node, and the core network to which the terminal device is registered includes a first AMF and a first UPF. A first backhaul link (i.e., wireless backhauling of the N2) is established between the mobile node and the first AMF. In the process of the terminal device initiating the establishment of the first session through the mobile node, the mobile node requests the core network to which the mobile node is registered to allocate address information to the mobile node. In the process shown in Figure 4, the address information allocated to the mobile node by the core network to which the mobile node is registered is public network address information.

[0122] As shown in Figure 4, the process may include the following steps:

[0123] Step 401: A mobile node sends a first request message to a first SMF, where the first request message is used to obtain address information of the mobile node.

[0124] In this step, the mobile node-terminal in the mobile node may send a first request message to the first SMF to request to obtain the address information of the mobile node-terminal. Exemplarily, the address information may be an IP address.

[0125] The address information of the mobile node is used to establish a user plane tunnel (or N3 tunnel) between the mobile node (mobile node-base station) and the first UPF. The user plane tunnel belongs to the first session between the terminal device accessing the mobile node and the first UPF. The first UPF is the UPF serving the terminal device.

[0126] Prior to step 401, the mobile node (mobile node-base station) receives an N2 message from the first AMF via the first backhaul link. The N2 message includes core network tunnel information (CN tunnel information) associated with the first session. The CN tunnel information includes the address information of the first UPF and the second TEID. The CN tunnel information is used by the mobile node-base station to determine the uplink user plane tunnel between the mobile node-base station and the first UPF.

[0127] In one possible implementation, after receiving the first request message, the first SMF determines whether to allocate private network address information or public network address information to the mobile node. If it is determined to allocate public network address information to the mobile node, the subsequent process is executed. If it is determined to allocate private network address information to the mobile node, the address can be allocated according to the process specified in the current protocol.

[0128] Optionally, the first SMF may determine whether to allocate public network address information to the mobile node according to one or more of the following:

[0129] - Determined based on the subscription information of the mobile node. If the subscription information indicates that the device type is a mobile node that can provide access services to terminal devices, determine to allocate public network address information to the mobile node.

[0130] -Determined according to the type of the third session. If the first request message received by the first SMF includes indication information for indicating the session type, and the indication information indicates that the type of the third session is a session for establishing a second backhaul link, the first SMF determines to allocate public network address information to the mobile node.

[0131] -Determined based on the Data Network Name (DNN) and / or Single Network Slice Selection Assistance Information (S-NSSAI) associated with the second session or the third session.

[0132] In one possible implementation, when a mobile node requests to modify a second session into a session for establishing a second backhaul link, the core network to which the mobile node is registered allocates address information to the mobile node. In this implementation, the first request message sent by the mobile node-terminal to the first SMF is used to request modification of the second session. Before the modification, the second session was used to establish the first backhaul link, and after the modification, the first session is used to establish the second backhaul link. In other words, the modified second session can be used by the mobile node-base station to access not only the first AMF but also the first UPF. Exemplarily, the mobile node-terminal can send an NAS message to the second AMF, which includes a session modification request, and the session modification request is used to request modification of the second session. The session modification request carries an identifier of the second session (such as a PDU Session ID). After receiving the NAS message, the second AMF determines the SMF associated with the second session (such as the first SMF) based on the PDU Session ID, and sends the session modification request therein to the first SMF.

[0133] Optionally, if the mobile node-base station determines, based on the address information of the first UPF, that the second session can be reused to access the first UPF, the mobile node-terminal is triggered to send a request message to modify the second session. For example, if it is determined, based on the address information of the first UPF, that the session for accessing the first AMF can be directly used to access the first UPF, such as if the first UPF and the core network to which the mobile node is registered belong to the same PLMN, then it is determined that the second session can be reused to access the first UPF.

[0134] Optionally, the first request message for requesting modification of the second session includes indication information, where the indication information is used to indicate that the session used to establish the first backhaul link is modified to a session used to establish the second backhaul link. After receiving the session modification request, the first SMF can determine to allocate public network address information to the mobile node based on the indication information.

[0135] Optionally, after receiving the session modification request, the first SMF may allocate public network address information to the mobile node according to the DNN and S-NSSAI associated with the second session.

[0136] Optionally, after receiving the session modification request, the first SMF may allocate public network address information to the mobile node according to the subscription information of the mobile node. For example, the subscription information indicates that the device type is a mobile node that can provide access services to terminal devices.

[0137] In another possible implementation, during the process of the mobile node requesting to establish the third session, the core network registered by the mobile node allocates address information to the mobile node. In this implementation, the first request message sent by the mobile node-terminal to the first SMF is used to request the establishment of the third session, and the third session is used to establish the second backhaul link. Exemplarily, the mobile node-terminal can send a NAS message to the second AMF, which includes a session establishment request, and the session establishment request is used to request the establishment of the third session; the session establishment request carries the identifier of the third session (such as PDU Session ID), DNN and S-NSSAI. After receiving the NAS message, the second AMF selects a suitable SMF (such as the first SMF) for the third session, and sends the session establishment request therein to the first SMF.

[0138] Optionally, the first SMF may allocate public network address information to the mobile node based on the DNN and S-NSSAI carried in the session establishment request.

[0139] Optionally, after receiving the session modification request, the first SMF may allocate public network address information to the mobile node according to the subscription information of the mobile node. For example, the subscription information indicates that the device type is a mobile node that can provide access services to terminal devices.

[0140] Optionally, if the mobile node-base station determines that the second session cannot be reused to access the first UPF based on the address information of the first UPF, the mobile node-terminal is triggered to send a request message to establish a third session. For example, if it is determined based on the address information of the first UPF that the session for accessing the first AMF cannot be directly used to access the first UPF, such as the first UPF and the core network to which the mobile node is registered belong to different PLMNs, it is determined that the second session cannot be reused to access the first UPF.

[0141] Optionally, the first request message for requesting establishment of the third session includes indication information for indicating the type of the third session, where the indication information indicates that the type of the third session is a session for establishing a second backhaul link, or the indication information is used to indicate that the third session is used to establish the second backhaul link. The first SMF may determine to allocate public network address information to the mobile node based on the indication information.

[0142] Step 402: The first SMF sends a second request message to the second UPF.

[0143] If the first request message received by the first SMF is used to modify the second session, the first SMF selects the second UPF as the anchor UPF for the modified second session and sends a second request message to the second UPF to modify the second session.

[0144] If the first request message received by the first SMF is used to establish the third session, the first SMF selects the second UPF as the anchor UPF of the third session and sends a second request message to the second UPF to establish the third session.

[0145] Step 403: The second UPF sends a second response message to the first SMF.

[0146] In another possible implementation, the public network address information of the mobile node is allocated to the mobile node by the second UPF based on the instruction of the first SMF. For example, based on the interaction between steps 402 and 403 above, in step 402, the second request message sent by the first SMF includes first indication information, and the first indication information instructs the second UPF to allocate public network address information to the mobile node, or instructs the second UPF to allocate private network address information to the mobile node and determine the public network address information corresponding to the private network address information. The first indication information can also be understood as an instruction to obtain the public network address information of the mobile node. In step 403, the second UPF allocates public network address information to the mobile node based on the first indication information, or allocates private network address information to the mobile node and determines the public network address information corresponding to the private network address information. The second UPF includes the public network address information of the mobile node in the second response message sent to the first SMF. An example of this implementation can be seen in Figure 6.

[0147] Optionally, the first request message includes the address information of the first UPF. In step 402, the first SMF may send the address information of the first UPF to the second UPF along with the address information of the first UPF. The second UPF may allocate public network address information to the mobile node based on the address information of the first UPF.

[0148] Optionally, after the second UPF allocates private network address information to the mobile node, it can determine the public network address information corresponding to the private network address information according to the NAT rule. Optionally, the second UPF can convert the private network address information to the public network address information according to a NAT method such as Full Cone NAT, Restricted Cone NAT, Port Restricted Cone NAT, or Symmetric NAT.

[0149] In another possible implementation, in addition to instructing the second UPF to allocate public network address information, the first SMF also sends the private network address information allocated by the first SMF to the second UPF to the mobile node. For example, based on the interaction of steps 402 and 403 above, in step 402, the second request message sent by the first SMF to the second UPF includes the private network address information allocated by the first SMF to the mobile node and second indication information, and the second indication information instructs the second UPF to determine the public network address information corresponding to the private network address information.

[0150] In step 403, the second UPF determines the corresponding public network address information according to the second indication information. The second UPF includes the public network address information of the mobile node in the second response message sent to the first SMF. An embodiment of this implementation method can be referred to Figure 7.

[0151] In another possible implementation, the public network address information of the mobile node is allocated to the mobile node by the first SMF. An example of this implementation can be seen in Figure 5. The interaction between step 402 and step 403 is used to modify or establish a session.

[0152] Optionally, the first request message includes the address information of the first UPF, and the public network address of the mobile node is determined by the first SMF based on the address information of the first UPF. The core network to which the mobile node is registered and the core network to which the terminal device is registered may belong to the same PLMN or different PLMNs. If they belong to different PLMNs, different PLMNs usually correspond to different address segments. Therefore, the first SMF can allocate address information within the corresponding address segment to the mobile node based on the address segment to which the address information of the first UPF belongs.

[0153] Optionally, after the second UPF allocates private network address information to the mobile node, it can determine the public network address information corresponding to the private network address information according to the NAT rule. Optionally, the second UPF can convert the private network address information to the public network address information according to a NAT method such as Full Cone NAT, Restricted Cone NAT, Port Restricted Cone NAT, or Symmetric NAT.

[0154] Step 404: The first SMF sends a first response message to the mobile node. The first response message includes the address information of the mobile node. The address information of the mobile node is public network address information.

[0155] Step 405: The mobile node sends its public network address information as tunnel information to the first UPF.

[0156] This step may include: in step 405a, the mobile node-terminal transmits the public network address information of the mobile node-terminal obtained from the first SMF to the mobile node-base station via the internal interface between the mobile node-base station and the mobile node-base station; in step 405b, the mobile node-base station transmits tunnel information to the first UPF, where the tunnel information includes the public network address information of the mobile node-terminal. Specifically, the mobile node-base station transmits an N2 message to the first AMF via the first backhaul link. The N2 message carries AN tunnel information, which includes the public network address information of the mobile node-terminal and the first TEID. The AN tunnel information is used by the first UPF to determine a downlink user plane tunnel with the first UPF of the mobile node-base station. The first AMF transmits the tunnel information to the first UPF via a second SMF (not shown in Figure 4).

[0157] It should be understood that the mobile node-terminal and the mobile node-base station may exchange information through an internal interface or through other means, which is not limited in this application.

[0158] It should be understood that the messages exchanged between the first SMF and the second UPF shown in Figure 4 above are only examples. For example, the message sent by the first SMF may also be an N4 session establishment request, and the message sent by the second UPF may also be an N4 session establishment response. This application does not limit this.

[0159] It should be understood that the messages exchanged between the first SMF and the mobile node shown in FIG4 are merely examples, and the present application does not limit this.

[0160] Based on the process shown in FIG4 , the uplink and downlink transmission process of a terminal device (hereinafter referred to as a UE) accessed through a mobile node may include:

[0161] The UE sends an uplink data message to the mobile node-base station via the air interface resources of the first session. After receiving the uplink data message, the mobile node-base station determines that the data was received via the user plane of the first session and further determines the core network tunnel information (CN tunnel information) associated with the first session. The mobile node-base station encapsulates the UE's uplink data into an N3 GTP-U message. The source IP address (Source IP) in the N3 GTP-U message is the public network address of the mobile node-terminal, the destination IP address (Destination IP) is the address of the first UPF in the CN tunnel information associated with the first session, and the header of the N3 GTP-U message includes a second TEID (the second TEID is obtained from the CN tunnel information and is used to identify the first UPF as the uplink data receiver). The mobile node-base station sends the N3 GTP-U message as a payload to the mobile node-terminal via an internal interface. The mobile node-terminal sends the N3 GTP-U message to the second UPF via the user plane tunnel of the third session.

[0162] After the second UPF receives the N3 GTP-U message, it unpacks the outer GTP-U header and takes out the inner message. Since the source address in the inner message (i.e., the private network address of the mobile node-terminal) is a public IP address, there is no need to perform NAT conversion. The second UPF forwards the NATed N3 GTP-U message to the first UPF according to the destination address of the N3 GTP-U message (the address of the first UPF).

[0163] After receiving the NATed N3 GTP-U message, the first UPF uses the source address in the received N3 GTP-U message (i.e., the public network address of the mobile node-terminal) to match the AN tunnel information received from the mobile node-base station during the first session establishment process. Since the mobile node-terminal address contained in the AN tunnel information is a public network address, the AN tunnel information containing the public network address can be matched, and the corresponding user plane tunnel can be determined, that is, the base station from which the uplink data comes can be determined.

[0164] When downlink transmission is performed for the UE, in the downlink N3 GTP-U message returned by the first UPF, the source address is the address of the first UPF, the destination address is the public network address of the mobile node-terminal, and the header of the N3 GTP-U message includes a first TEID, which is used to identify the mobile node-base station as the receiving end of the downlink data.

[0165] According to the above-mentioned uplink and downlink transmission processes, it can be seen that since the address information assigned to the mobile node by the core network to which the mobile node is registered is public network address information, during the uplink transmission process, when the uplink message is sent to the UPF providing services for the terminal device, the UPF can match the source address information in the uplink message (i.e., the public network address information of the mobile node) to the public network address information in the tunnel information it saves, that is, it can match the corresponding user plane tunnel, thereby ensuring the service transmission of the terminal device.

[0166] Based on the process shown in Figure 4, Figure 5 shows an example of the process shown in Figure 4. Figure 5 takes the MWAB device as an example. During the first session establishment process, the first SMF allocates a public IP address to the MWAB-UE. The MWAB-UE sends the public IP address to the MWAB-gNB. The MWAB-gNB sends the public IP address as tunnel information to the first UPF that provides services for ordinary UEs (the ordinary UEs access the network through the MWAB-UE).

[0167] In Figure 5, the MWAB-UE is registered with the second AMF, which is the AMF serving the MWAB-UE. A second session is established between the MWAB-UE and the second UPF in the core network with which it is registered. This second session is used for the MWAB-gNB to access the first AMF, where a first backhaul link (i.e., N2 connection) is established between the MWAB-gNB and the first AMF.

[0168] It should be understood that the second session may also be established between the MWAB-UE and other UPFs (ie, other UPFs other than the second UPF in the core network to which the MWAB-UE is registered).

[0169] The MWAB-gNB can provide network access services for normal UEs, which register with the network through the MWAB-gNB. For normal UEs accessing through the MWAB-gNB, communication with the first AMF is performed over the first backhaul link. In other words, the first AMF can provide services for the normal UE.

[0170] After a common UE initiates a first session establishment request through the MWAB-gNB, as shown in Figure 5, the process may include the following steps:

[0171] Step 501: The ordinary UE initiates the first session establishment process to the core network where the ordinary UE is registered through the MWAB-gNB.

[0172] In this step, the normal UE sends a NAS message to the first AMF through the MWAB-gNB. The NAS message includes a session establishment request for establishing a first session. The first AMF selects an appropriate SMF for the first session of the normal UE. For example, the first AMF selects the second SMF. The first AMF sends the session establishment request to the second SMF.

[0173] Step 502: The second SMF selects a UPF for the first session. Taking the selection of the first UPF as an example, an N4 session is established between the second SMF and the first UPF.

[0174] Step 503: The second SMF returns first information and second information to the first AMF. The first information includes an N2 SM container, which contains core network tunnel information (CN tunnel information). The second information includes an N1 SM container.

[0175] Among them, the CN tunnel information includes the tunnel endpoint identification (TEID) and the IP address of the first UPF. TEID uniquely identifies the endpoint of a GTP tunnel. TEID is allocated by the receiving end and transmitted to the sending end through a control plane message. When sending a message, the sending end carries the TEID of the receiving end to identify which receiving end the message is sent to. Here, because the first UPF needs to receive the uplink GTP-U message sent by the MWAB-gNB, the first UPF allocates the TEID of the uplink GTP tunnel. For the sake of distinction, this TEID is called the second TEID.

[0176] Step 504: The first AMF sends the first information and the second information to the MWAB-gNB.

[0177] Step 505: The MWAB-gNB obtains the IP address of the first UPF based on the CN tunnel information contained in the N2 SM container. The MWAB-gNB triggers the MWAB-UE to initiate a third session establishment process through the internal interface. The third session is used to access the first UPF through the network to which the MWAB-UE is currently registered.

[0178] Step 506: The MWAB-UE sends a NAS message to the second AMF in the core network where it is registered. The NAS message includes a session establishment request (e.g., PDU Session Establishment Request). The second AMF sends the session establishment request in the NAS message to the first SMF selected by the second AMF for the third session of the MWAB-UE.

[0179] The session establishment request carries the DNN and / or S-NSSAI.

[0180] Optionally, the session establishment request includes indication information, where the indication information is used to indicate the type of the third session, where the type of the third session is a session for establishing the second backhaul link, or in other words, the indication information indicates that the third session is a session for establishing the second backhaul link.

[0181] Optionally, the session establishment request includes the IP address of the first UPF.

[0182] Step 507: After receiving the session establishment request, the first SMF determines whether the third session requested to be established is a session for establishing a second backhaul link. If yes, it determines to allocate a public IP address to the MWAB-UE.

[0183] Optionally, the first SMF may determine whether the third session is used to establish the second backhaul link, or whether the third session is used as a wireless backhauling session based on the DNN or S-NSSAI carried in the session establishment request.

[0184] Optionally, the first SMF may determine whether the third session is used to establish the second backhaul link, or whether the third session is used as a wireless backhauling session, based on indication information carried in the session establishment request.

[0185] Optionally, the first SMF may obtain information indicating the type of the device from the subscription information of the MWAB-UE, and determine whether the device is a MWAB-UE based on the information.

[0186] Step 508: The first SMF allocates a public IP address (MWAB-UE IP) to the MWAB-UE.

[0187] Optionally, the first SMF can determine the public IP address of the MWAB-UE based on the IP address of the first UPF.

[0188] Step 508 can be described with reference to FIG. 4 and will not be repeated here.

[0189] Step 509: In the process of establishing the third session, the first SMF sends an N4 session establishment request to the second UPF.

[0190] Step 510: The second UPF returns an N4 session establishment response to your first SMF.

[0191] Step 511: The first SMF sends a first message to the MWAB-UE, which includes a public IP address.

[0192] Optionally, the first message may be a session establishment response (PDU Session Establishment Response).

[0193] Step 512: The MWAB-UE sends the public IP address to the MWAB-gNB through the internal interface.

[0194] Step 513: The MWAB-gNB continues the first session establishment process for the normal UE. The MWAB-gNB sends the second information received in step 504 to the normal UE.

[0195] Step 514: The MWAB-gNB determines the access network tunnel information (AN tunnel information) for the first session. The AN tunnel information includes the public IP address of the MWAB-UE. The MWAB-gNB sends an N2 message (e.g., N2 PDU Session Response) to the first AMF, including the AN tunnel information.

[0196] The AN tunnel information includes the TEID and the IP address of the MWAB-gNB. The MWAB-gNB IP address is a public IP address. Because the MWAB-gNB receives downlink GTP-U messages from the first UPF, the MWAB-gNB allocates a TEID for the downlink GTP tunnel to identify the MWAB-gNB receiving the downlink data. For differentiation, this TEID is referred to as the first TEID.

[0197] Step 515: The network continues to execute the first session establishment process, for example, including the first AMF sending the AN tunnel information to the first UPF through the second SMF.

[0198] In an implementation similar to the process shown in FIG5 , the difference from the process shown in FIG5 is that the first SMF does not allocate an IP address to the MWAB-UE. Instead, the second UPF allocates the IP address to the MWAB-UE. In this case, the first SMF includes first indication information in the N4 session establishment request sent to the second UPF, which instructs the second UPF to allocate a public IP address to the MWAB-UE. The second UPF allocates a public IP address to the MWAB-UE based on the indication information and sends it to the first SMF via an N4 session establishment response.

[0199] Optionally, the N4 session establishment request may also carry the first UPF address information. The second UPF may allocate a public network IP address to the MWAB-UE based on the first UPF IP address.

[0200] In an implementation similar to the process shown in Figure 5 above, the difference from the process shown in Figure 5 is that the MWAB-UE sends a second session modification request to the first SMF (the first SMF is the SMF associated with the second session) instead of a third session establishment request. Accordingly, the first SMF and the second UPF perform the second session modification process to modify the second session into a session for establishing the second backhaul link. The second session modification request carries the identifier of the second session (such as the PDU Session ID).

[0201] Optionally, the second session modification request includes indication information, which is used to indicate that the session used to establish the first backhaul link is modified to a session used to establish the second backhaul link. After receiving the session modification request, the first SMF can determine to allocate public network address information to the mobile node based on the indication information.

[0202] Optionally, after receiving the session modification request, the first SMF may allocate public network address information to the mobile node according to the DNN and S-NSSAI associated with the second session.

[0203] Optionally, after receiving the session modification request, the first SMF may allocate public network address information to the mobile node according to the subscription information of the mobile node. For example, the subscription information indicates that the device type is a mobile node that can provide access services to terminal devices.

[0204] Optionally, the session modification request includes the IP address of the first UPF, and the first SMF can determine the public IP address of the MWAB-UE based on the IP address of the first UPF.

[0205] Based on the process shown in Figure 4, Figure 6 shows an example of the process shown in Figure 4. Figure 6 takes the MWAB device as an example. During the first session establishment process, the core network in which the MWAB-UE is registered allocates a public IP address to the MWAB-UE. The MWAB-UE sends the public IP address to the MWAB-gNB. The MWAB-gNB sends the public IP address as tunnel information to the first UPF providing services for a normal UE (the normal UE accesses the network through the MWAB-UE).

[0206] In Figure 6, the MWAB-UE is registered with the second AMF, which is the AMF serving the MWAB-UE. A second session is established between the MWAB-UE and the second UPF in the core network with which it is registered. This second session is used for the MWAB-gNB to access the first AMF, where a first backhaul link (i.e., N2 connection) is established between the MWAB-gNB and the first AMF.

[0207] The MWAB-gNB can provide network access services for normal UEs, which register with the network through the MWAB-gNB. For normal UEs accessing through the MWAB-gNB, communication with the first AMF is performed over the first backhaul link. In other words, the first AMF can provide services for the normal UE.

[0208] The specific implementation of steps 601 to 607 in FIG6 can refer to the implementation of steps 501 to 507 in FIG5 , and the specific implementation of steps 610 to 614 in FIG6 can refer to the specific implementation of steps 511 to 515 in FIG5 , which will not be repeated here. The difference between the process shown in FIG6 and the process shown in FIG5 is that:

[0209] In step 608, the first SMF sends an N4 session establishment request to the second UPF, including first indication information, which instructs the second UPF to allocate private network address information to the mobile node and determine the public network address information corresponding to the private network address information. Alternatively, the first indication information is directly used to instruct the second UPF to allocate public network address information to the mobile node.

[0210] Optionally, if the first SMF determines that the second UPF supports the NAT function, the first indication information is carried in the N4 session establishment request sent to the second UPF.

[0211] Optionally, if the first SMF determines that the third session is a session for establishing a second backhaul link based on the DNN or S-NSSAI carried in the session establishment request, the first indication information is carried in the N4 session establishment request sent to the second UPF.

[0212] Optionally, if the first SMF determines, based on the indication information carried in the session establishment request, that the third session is a session for establishing a second backhaul link, the first indication information is carried in the N4 session establishment request sent to the second UPF.

[0213] Optionally, if the first SMF obtains information indicating the type of the device from the subscription information of the MWAB-UE and determines that the device is a MWAB-UE based on the information, the first indication information is carried in the N4 session establishment request sent to the second UPF.

[0214] In step 609, the second UPF allocates a private IP address (MWAB-UE IP) to the MWAB-UE based on the first indication information, and determines the corresponding public IP address (NATed IP) based on the private IP address (MWAB-UE IP). Alternatively, if the second UPF learns from the indication information that a public IP address needs to be allocated to the MWAB-UE, it directly allocates the public IP address. The second UPF sends an N4 session establishment response to the first SMF, which carries the public IP address.

[0215] Optionally, the N4 session establishment request may also include the IP address of the first UPF, and the second UPF may determine the IP address (NATed IP) of the MWAB-UE IP after NAT, that is, the public network address, based on the IP address of the first UPF.

[0216] In an implementation similar to the process shown in Figure 6 above, the difference from the process shown in Figure 6 is that the MWAB-UE sends a second session modification request to the first SMF (the first SMF is the SMF associated with the second session) instead of a third session establishment request. Accordingly, the first SMF and the second UPF perform the second session modification process to modify the second session into a session for establishing the second backhaul link. For a detailed description, please refer to Figure 5.

[0217] Based on the process shown in Figure 4, Figure 7 shows an example of the process shown in Figure 4. Figure 7 takes the MWAB device as an example. During the first session establishment process, the core network where the MWAB-UE is registered allocates a public IP address to the MWAB-UE. The MWAB-UE sends the public IP address to the MWAB-gNB. The MWAB-gNB sends the public IP address as tunnel information to the first UPF providing services for the ordinary UE (the ordinary UE accesses the network through the MWAB-UE).

[0218] In Figure 7 , the MWAB-UE is registered with the second AMF, which is the AMF serving the MWAB-UE. A second session is established between the MWAB-UE and the second UPF in the core network with which it is registered. This second session is used for the MWAB-gNB to access the first AMF, where a first backhaul link (i.e., N2 connection) is established between the MWAB-gNB and the first AMF.

[0219] The MWAB-gNB can provide network access services for normal UEs, which register with the network through the MWAB-gNB. For normal UEs accessing through the MWAB-gNB, communication with the first AMF is performed over the first backhaul link. In other words, the first AMF can provide services for the normal UE.

[0220] The specific implementation of steps 701 to 707 in FIG. 7 can refer to the implementation of steps 501 to 507 in FIG. 5 , and the specific implementation of steps 710 to 714 in FIG. 7 can refer to the specific implementation of steps 511 to 515 in FIG. 5 , which will not be repeated here. The difference between the process shown in FIG. 7 and the process shown in FIG. 5 is that:

[0221] In step 708, the first SMF allocates a private IP address (MWAB-UE IP) to the MWAB-UE and sends an N4 session establishment request to the second UPF, which includes the private IP address (MWAB-UE IP) and second indication information. The second indication information instructs the second UPF to determine the public IP address based on the private IP address.

[0222] Optionally, if the first SMF determines that the second UPF supports the NAT function, the second indication information is carried in the N4 session establishment request sent to the second UPF.

[0223] Optionally, if the first SMF determines that the third session is a session for establishing a second backhaul link based on the DNN or S-NSSAI carried in the session establishment request, the second indication information is carried in the N4 session establishment request sent to the second UPF.

[0224] Optionally, if the first SMF determines that the third session is a session for establishing a second backhaul link based on the indication information carried in the session establishment request, the second indication information is carried in the N4 session establishment request sent to the second UPF.

[0225] Optionally, if the first SMF obtains information indicating the type of the device from the subscription information of the MWAB-UE and determines that the device is a MWAB-UE based on the information, the second indication information is carried in the N4 session establishment request sent to the second UPF.

[0226] In step 709, the second UPF determines the public IP address (NATed IP) corresponding to the private IP address according to the second indication information. The second UPF sends an N4 session establishment response to the first SMF, which carries the public IP address.

[0227] Optionally, the N4 session establishment request may further include the IP address of the first UPF, and the second UPF may determine the IP address (NATed IP) of the MWAB-UE IP after NAT based on the IP address of the first UPF.

[0228] In an implementation similar to the process shown in Figure 7 above, the difference from the process shown in Figure 7 is that the MWAB-UE sends a second session modification request to the first SMF instead of a third session establishment request. Accordingly, the first SMF and the second UPF perform the second session modification process to modify the second session into a session for establishing the second backhaul link. For a detailed description, see Figure 5.

[0229] Refer to Figure 8, which is a flow chart of a communication method provided in an embodiment of the present application. In this method, the mobile node has registered with the core network, and the core network includes a second AMF, a first SMF, and a second UPF. A second session is established between the mobile node and the second UPF in the core network. The terminal device accesses the network through the mobile node, and the core network to which the terminal device is registered includes a first AMF and a first UPF. A first backhaul link is established between the terminal device and the first AMF it accesses. In the process of the terminal device initiating the establishment of the first session through the mobile node, the mobile node requests the core network to which the mobile node is registered to allocate address information to the mobile node.

[0230] In the process shown in Figure 8, the address information allocated to the mobile node by the core network to which the mobile node is registered is private network address information. When the mobile node sends the private network address information and the TEID determined by the mobile node as tunnel information to the first UPF, it also sends indication information, which instructs the first UPF to determine the user plane tunnel based on the TEID in the tunnel information.

[0231] As shown in Figure 8, the process may include the following steps:

[0232] Step 801: A mobile node sends a first request message to a first SMF, where the first request message is used to obtain address information of the mobile node.

[0233] In this step, the mobile node-terminal in the mobile node may send a first request message to the first SMF to request to obtain the address information of the mobile node-terminal. Exemplarily, the address information may be an IP address.

[0234] The address information of the mobile node is used to establish a user plane tunnel (or N3 tunnel) between the mobile node and the first UPF. The user plane tunnel belongs to the first session between the terminal device accessing the mobile node and the first UPF. The first UPF is the UPF serving the terminal device.

[0235] In one possible implementation, during a mobile node's request to modify the second session into a session for establishing a second backhaul link, the core network with which the mobile node is registered allocates address information to the mobile node. In this implementation, the mobile node-terminal sends a first request message to the first SMF to request modification of the second session. Before the modification, the second session is used to establish the first backhaul link, and after the modification, the first session is used to establish the second backhaul link. In other words, the modified second session can be used by the mobile node-base station to access not only the first AMF but also the first UPF. Exemplarily, the mobile node-terminal can send an NAS message to the second AMF, including a session modification request, to request modification of the second session. After receiving the NAS message, the second AMF sends the session modification request therein to the first SMF.

[0236] Optionally, if the mobile node-base station determines, based on the address information of the first UPF, that the second session can be reused to access the first UPF, the mobile node-terminal is triggered to send a request message to modify the second session. For example, if it is determined, based on the address information of the first UPF, that the session for accessing the first AMF can be directly used to access the first UPF, such as if the first UPF and the core network to which the mobile node is registered belong to the same PLMN, then it is determined that the second session can be reused to access the first UPF.

[0237] In another possible implementation, during the mobile node's request to establish a third session, the core network with which the mobile node is registered allocates address information to the mobile node. In this implementation, the first request message sent by the mobile node-terminal to the first SMF is used to request establishment of the third session, which is used to establish the second backhaul link. Exemplarily, the mobile node-terminal may send an NAS message to the second AMF, including a session establishment request, requesting establishment of the third session. Upon receiving the NAS message, the second AMF sends the session establishment request to the first SMF.

[0238] Optionally, if the mobile node-base station determines that the second session cannot be reused to access the first UPF based on the address information of the first UPF, the mobile node-terminal is triggered to send a request message to establish a third session. For example, if it is determined based on the address information of the first UPF that the session for accessing the first AMF cannot be directly used to access the first UPF, such as the first UPF and the core network to which the mobile node is registered belong to different PLMNs, it is determined that the second session cannot be reused to access the first UPF.

[0239] Step 802: The first SMF sends a first response message to the mobile node, where the first response message includes the address information of the mobile node, which is private network address information.

[0240] In one implementation, after receiving the first request message, the first SMF allocates private network address information to the mobile node-terminal.

[0241] In another implementation, if the first request message received by the first SMF is for modifying the second session, the first SMF selects the second UPF as the anchor UPF for the modified second session and sends a second request message to the second UPF to modify the second session. The second UPF carries the private network address information allocated by the second UPF to the mobile node-terminal in a second response message returned to the first SMF.

[0242] In another implementation, if the first request message received by the first SMF is for establishing a third session, the first SMF selects the second UPF as the anchor UPF for the third session and sends a second request message to the second UPF to establish the third session. The second UPF carries the private network address information allocated by the second UPF to the mobile node-terminal in a second response message returned to the first SMF.

[0243] Step 803: The mobile node sends tunnel information and indication information to the first UPF. The tunnel information includes the address information of the mobile node and the first TEID. The indication information instructs the first UPF to determine the user plane tunnel according to the TEID in the uplink message.

[0244] This step may include: in step 803a, the mobile node-terminal transmits the address information of the mobile node-terminal obtained from the first SMF to the mobile node-base station via an internal interface between the mobile node-terminal and the mobile node-base station; in step 803b, the mobile node-base station transmits tunnel information and the indication information to the first UPF, where the tunnel information includes the address information of the mobile node-terminal and a first TEID. The first TEID is allocated by the mobile node-base station and is used to identify a receiving end of downlink data, that is, to identify the mobile node-base station.

[0245] Optionally, since the address information of the mobile node-terminal is private network address information, the mobile node-base station determines to generate the indication information to instruct the UPF to perform user plane tunnel matching according to the TEID in the uplink message.

[0246] It should be understood that the mobile node-terminal and the mobile node-base station may exchange information through an internal interface or through other means, which is not limited in this application.

[0247] In a possible implementation, the process shown in FIG8 may further include the following steps before step 801:

[0248] Step 800: The mobile node receives the address information of the first UPF and the second TEID.

[0249] For example, during a first session, the first UPF sends core network tunnel information to the second SMF in response to the first session establishment request. The second SMF then sends this core network tunnel information to the mobile node-terminal. This core network tunnel information includes the address information of the first UPF and the second TEID. The second TEID is allocated by the first UPF and is used to identify the receiving end of the uplink data, that is, the first UPF.

[0250] Based on step 800, correspondingly, in step 803, the mobile node-base station sends a user plane message to the first UPF according to the address information and the second TEID of the first UPF, where the user plane message includes the tunnel information and indication information determined by the mobile node-base station.

[0251] Based on the process shown in FIG8 , the uplink transmission process of a terminal device (hereinafter referred to as a UE) accessed through a mobile node may include:

[0252] The UE sends an uplink data message to the mobile node-base station via the air interface resources of the first session. After receiving the uplink data message, the mobile node-base station determines that the data was received via the user plane of the first session and further determines the core network tunnel information (CN tunnel information) associated with the first session. The mobile node-base station encapsulates the UE's uplink data into an N3 GTP-U message. The source IP address (Source IP) in the N3 GTP-U message is the private network address of the mobile node-terminal, the destination IP address (Destination IP) is the address of the first UPF in the CN tunnel information associated with the first session, and the header of the N3 GTP-U message includes a second TEID (the second TEID is included in the CN tunnel information). The mobile node-base station sends the N3 GTP-U message as a payload to the mobile node-terminal via an internal interface. The mobile node-terminal sends the N3 GTP-U message to the second UPF via the user plane tunnel of the third session.

[0253] After receiving the N3 GTP-U message, the second UPF decapsulates the outer GTP-U header and takes out the inner message, performs NAT conversion on the source address in the inner message (i.e., the private network address of the mobile node-terminal), converts it into a public network address, and forwards the NATed N3 GTP-U message to the first UPF according to the destination address of the N3 GTP-U message (the address of the first UPF).

[0254] After receiving the NATed N3 GTP-U message, the first UPF uses the TEID in the received N3 GTP-U message to match the user plane tunnel based on the indication information received from the mobile node-base station during the first session establishment process. Specifically, the UPF can match the corresponding user plane tunnel based on the second TEID in the N3 GTP-U message, thereby obtaining the first TEID corresponding to the user plane tunnel. Furthermore, the UPF can determine the address information of the mobile node-terminal based on the first TEID and the AN tunnel information received during the first session establishment process, and further determine which base station the uplink data comes from.

[0255] When downlink transmission is performed for the UE, in the downlink N3 GTP-U message returned by the first UPF, the source address is the address of the first UPF, the destination address is the public network address of the mobile node-terminal, and the header of the N3 GTP-U message includes a first TEID, which is used to identify the receiving mobile node-base station.

[0256] According to the above-mentioned uplink and downlink transmission process, it can be seen that during the establishment of the first session, the mobile node instructs the first UPF (i.e., the anchor point UPF of the first session) to use the TEID in the uplink message to match the user plane tunnel through the indication information, so that the UPF can match the corresponding user plane tunnel according to the first TEID in the uplink message, determine which base station the uplink message comes from, and thus ensure the service transmission of the terminal device.

[0257] Based on the process shown in Figure 8, Figure 9 shows an example of the process shown in Figure 8. Figure 9 takes the MWAB device as an example. During the first session establishment process, the first SMF allocates a public IP address to the MWAB-UE. The MWAB-UE sends the public IP address to the MWAB-gNB. The MWAB-gNB sends the public IP address as tunnel information to the first UPF providing services for the ordinary UE (the ordinary UE accesses the network through the MWAB-UE).

[0258] In Figure 9, the MWAB-UE is registered with the second AMF, which is the AMF serving the MWAB-UE. A second session is established between the MWAB-UE and the second UPF in the core network with which it is registered. This second session is used for the MWAB-gNB to access the first AMF, where a first backhaul link (i.e., N2 connection) is established between the MWAB-gNB and the first AMF.

[0259] It should be understood that the second session may also be established between the MWAB-UE and other UPFs (ie, other UPFs other than the second UPF in the core network to which the MWAB-UE is registered).

[0260] The MWAB-gNB can provide network access services for normal UEs, which register with the network through the MWAB-gNB. For normal UEs accessing through the MWAB-gNB, communication with the first AMF is performed over the first backhaul link. In other words, the first AMF can provide services for the normal UE.

[0261] After a common UE initiates a first session establishment request through the MWAB-gNB, as shown in Figure 9, the process may include the following steps:

[0262] Step 901: The ordinary UE initiates the first session establishment process to the core network where the ordinary UE is registered through the MWAB-gNB.

[0263] In this step, the normal UE sends a NAS message to the first AMF through the MWAB-gNB. The NAS message includes a session establishment request for establishing a first session. The first AMF selects an appropriate SMF for the first session of the normal UE. For example, the first AMF selects the second SMF. The first AMF sends the session establishment request to the second SMF.

[0264] Step 902: The second SMF selects a UPF for the first session. Taking the selection of the first UPF as an example, an N4 session is established between the second SMF and the first UPF.

[0265] Step 903: The second SMF returns first information and second information to the first AMF. The first information includes an N2 SM container, which contains core network tunnel information (CN tunnel information). The second information includes an N1 SM container.

[0266] The CN tunnel information includes the second TEID and the IP address of the first UPF. The second TEID is the TEID allocated by the first UPF for the uplink GTP tunnel.

[0267] Step 904: The first AMF sends the first information and the second information to the MWAB-gNB.

[0268] Step 905: The MWAB-gNB obtains the IP address of the first UPF based on the CN tunnel information contained in the N2 SM container. The MWAB-gNB triggers the MWAB-UE to initiate a third session establishment process through the internal interface. The third session is used to access the first UPF through the network to which the MWAB-UE is currently registered.

[0269] Step 906: The MWAB-UE sends a NAS message to the second AMF in the core network with which it is registered. The NAS message includes a session establishment request (e.g., PDU Session Establishment Request). The second AMF sends the session establishment request in the NAS message to the first SMF selected by the second AMF for the third session of the MWAB-UE.

[0270] Step 907: In the process of establishing the third session, the first SMF sends an N4 session establishment request to the second UPF.

[0271] Step 908: The second UPF returns an N4 session establishment response to your first SMF.

[0272] Step 909: The first SMF sends a first message to the MWAB-UE, which includes the private IP address of the MWAB-UE.

[0273] Optionally, the private IP address of the MWAB-UE can be allocated by the first SMF or the second UPF.

[0274] Optionally, the first message may be a session establishment response (PDU Session Establishment Response).

[0275] Step 910: The MWAB-UE sends the private network IP address to the MWAB-gNB through the internal interface.

[0276] Step 911: The MWAB-gNB continues the first session establishment process for the normal UE. The MWAB-gNB sends the second information received in step 904 to the normal UE.

[0277] Step 912: The MWAB-gNB determines the access network tunnel information (AN tunnel information) for the first session. The MWAB-gNB sends an N2 message (e.g., N2 PDU Session Response) to the first AMF, including the AN tunnel information and indication information, which instructs the first UPF to match the user plane tunnel based on the TEID in the uplink message.

[0278] The AN tunnel information includes a first TEID and the private IP address of the MWAB-gNB. The first TEID is a TEID assigned by the MWAB-gNB for the downlink GTP tunnel and is used to identify the MWAB-gNB receiving the downlink data.

[0279] Step 913: The network continues to execute the first session establishment process, for example, including the first AMF sending the AN tunnel information and indication information to the first UPF through the second SMF.

[0280] In an implementation similar to the process shown in FIG9 , the difference from the process shown in FIG9 is that the MWAB-UE sends a second session modification request to the first SMF instead of a third session establishment request. Accordingly, the first SMF and the second UPF perform the second session modification process to modify the second session into a session for establishing the second backhaul link.

[0281] Refer to Figure 10, which is a flow chart of a communication method provided in an embodiment of the present application. In this method, the mobile node has registered with the core network, and the core network includes a second AMF, a first SMF, and a second UPF. A second session is established between the mobile node and the second UPF in the core network. The terminal device accesses the network through the mobile node, and the core network to which the terminal device is registered includes a first AMF and a first UPF. A first backhaul link is established between the terminal device and the first AMF it accesses. In the process of the terminal device initiating the establishment of the first session through the mobile node, the mobile node requests the core network to which the mobile node is registered to allocate address information to the mobile node. In the process shown in Figure 10, the address information allocated to the mobile node by the core network to which the mobile node is registered is private network address information.

[0282] As shown in Figure 10, the process may include the following steps:

[0283] Step 1001: A mobile node sends a first uplink message to a first UPF, where the first uplink message indicates a correspondence between the private network address information and the public network address information of the mobile node.

[0284] In one possible implementation, a header of the first uplink message includes private network address information of the mobile node, and a payload of the first uplink message includes source address information, which is converted from the private network address information of the mobile node to public network address information. During transmission of the first uplink message, the second UPF converts the source address in the payload of the first uplink message from a private network address to a public network address. In this way, the first uplink message received by the first UPF includes the private network address information of the mobile node in its header, and the public network address information converted by the second UPF in its payload, so that the first uplink message can indicate the correspondence between the private network address information and the public network address information of the mobile node.

[0285] In a possible implementation, after the mobile node obtains address information allocated to the mobile node from the core network with which it is registered, if the address information is private network address information, the mobile node generates the first uplink message.

[0286] Step 1002: The first UPF obtains the correspondence between the private network address information and the public network address information of the mobile node according to the first uplink message.

[0287] In this step, the first UPF can obtain the private network address information of the mobile node from the message header of the first uplink message, and obtain the source address information from the payload of the first uplink message, where the source address information is the public network address information of the mobile node.

[0288] Step 1003: The mobile node sends a second uplink message to the first UPF.

[0289] The message header of the second uplink message may not include the address information of the mobile node.

[0290] During the transmission of the second uplink message, the second UPF converts the source address in the payload of the second uplink message from private network address information to public network address information.

[0291] Step 1004: The first UPF determines the private network address information corresponding to the source address information based on the source address information in the second uplink message and the corresponding relationship, where the source address is the public network address information of the mobile node. The first UPF determines the corresponding user plane tunnel based on the private network address information.

[0292] In a possible implementation, before step 1001, the process of establishing the first session initiated by the terminal device may include the following steps:

[0293] Step 1000a: The first SMF sends the address information of the mobile node to the mobile node, where the address information is private network address information.

[0294] In this step, the first SMF sends the address information of the mobile node-terminal to the mobile node-terminal, and the mobile node-terminal sends the address information to the mobile node-base station through the internal interface between the mobile node-terminal and the mobile node-base station.

[0295] Step 1000b: The mobile node sends the tunnel information to the first UPF, where the tunnel information includes the address information of the mobile node, which is private network address information. The tunnel information is used to establish a user plane tunnel between the mobile node and the first UPF.

[0296] Correspondingly, in step 1004, after the first UPF determines the corresponding private network address information based on the source address information (public network address information) in the second uplink message and the corresponding relationship, it can determine the corresponding user plane tunnel based on the private network address information and the tunnel information.

[0297] According to the above transmission process, it can be seen that the mobile node sends the correspondence between the private network address information and the public network address information of the mobile node to the first UPF via the first uplink message. During the uplink transmission process, when the second uplink message is sent to the UPF providing services for the terminal device, even if the source address information in the second uplink message is converted into public network address information by the second UPF, the first UPF can still determine the private network address information of the mobile node based on the correspondence, and thus can match the private network address information with the private network address information in the tunnel information it stores, that is, it can match the corresponding user plane tunnel, thereby ensuring the service transmission of the terminal device.

[0298] Refer to Figure 11, which is a flow chart of a communication method provided in an embodiment of the present application. In this method, the mobile node has registered with the core network, and the core network includes a second AMF, a first SMF, and a second UPF. A second session is established between the mobile node and the second UPF in the core network. The terminal device accesses the network through the mobile node, and the core network to which the terminal device is registered includes a first AMF and a first UPF. A first backhaul link is established between the terminal device and the first AMF it accesses. In the process of the terminal device initiating the establishment of the first session through the mobile node, the mobile node requests the core network to which the mobile node is registered to allocate address information to the mobile node. In the process shown in Figure 11, the address information allocated to the mobile node by the core network to which the mobile node is registered is private network address information.

[0299] As shown in Figure 11, the process may include the following steps:

[0300] Step 1101: The first SMF sends address information allocated to the mobile node to the mobile node, where the address information is private network address information.

[0301] During the process of establishing the first session, the core network where the mobile node is registered may allocate address information to the mobile node. Specific implementation methods may refer to the process shown in FIG9 .

[0302] Step 1102: The mobile node sends a request message to a server for providing a service for information about the public network address after address conversion. The request message is used to obtain the public network address information after the private network address of the mobile node is converted.

[0303] For example, the server for providing the public network address information service after address conversion is a STUN server.

[0304] Optionally, after the mobile node obtains the address information allocated to the mobile node from the core network where it is registered, if the address information is private network address information, the mobile node determines that it needs to obtain the corresponding public network address information from the server.

[0305] Step 1103: The server returns a response message to the mobile node. The response message includes the public network address information converted based on the private network address information of the mobile node.

[0306] Step 1104: The mobile node sends tunnel information (eg, AN tunnel information) to the first UPF, where the tunnel information includes the obtained public network address information.

[0307] The tunnel information is used to establish a user plane tunnel between the mobile node and the first UPF, and the user plane tunnel belongs to the first session between the terminal device accessing the mobile node and the first UPF.

[0308] In the above process, the mobile node can be configured as a STUN client and the server can be configured as a STUN server. Based on the STUN protocol, the mobile node can obtain the public network address information corresponding to its private network address information. For specific implementation methods, please refer to the relevant description of the STUN protocol above.

[0309] It should be understood that the mobile node and the server may also adopt other similar protocols so that the mobile node can obtain the public network address information corresponding to its private network address information, and this application does not impose any restrictions on this.

[0310] In the process shown in Figure 11, after the mobile node obtains the public network address information corresponding to the private network address information assigned to it, it sends it to the first UPF as tunnel information. Therefore, during the uplink transmission process, when the uplink message is sent to the UPF providing services for the terminal device, the UPF can match the source address information in the uplink message (i.e., the public network address information of the mobile node) to the public network address information in the tunnel information it saves, that is, it can match the corresponding user plane tunnel, thereby ensuring the service transmission of the terminal device.

[0311] It should be understood that in the above embodiments of the present application, the information interaction method between the mobile node-terminal and the mobile node-base station may adopt other methods besides the internal interface method, such as the shared memory method, which is not limited by the present application.

[0312] It is understood that in order to implement the functions in the above embodiments, the network devices and terminal devices include hardware structures and / or software modules corresponding to the execution of each function. Those skilled in the art should readily appreciate that, in combination with the units and method steps of each example described in the embodiments disclosed in this application, the present application can be implemented in the form of hardware or a combination of hardware and computer software. Whether a function is executed in hardware or in a manner driven by computer software depends on the specific application scenario and design constraints of the technical solution.

[0313] Figures 12 and 13 are schematic diagrams of possible communication devices provided in embodiments of the present application. These communication devices can be used to implement the functions of the mobile node, UPF, or SMF in the above-mentioned method embodiments, thereby also achieving the beneficial effects of the above-mentioned method embodiments. In embodiments of the present application, the communication device can be the above-mentioned device or a module (such as a chip) in the above-mentioned device.

[0314] As shown in Figure 12, the communication device 1200 includes a processing unit 1210 and a transceiver unit 1220. The communication device 1200 is used to implement the functions of the mobile node, UPF or SMF in the method embodiment shown in any of Figures 4 to 11 above.

[0315] When the communication device 1200 is used to implement the function of the first SMF in the method embodiment shown in Figures 4 to 7 above: the processing unit 1210 sends the address information of the mobile node to the mobile node through the transceiver unit 1220, and the address information of the mobile node is public network address information; wherein the address information of the mobile node is used to establish a user plane tunnel between the mobile node and the first UPF, and the user plane tunnel belongs to the first session between the terminal device accessing the mobile node and the first UPF, the first UPF is the UPF serving the terminal device, and the mobile node is used to provide access services for the terminal device.

[0316] When the communication device 1200 is used to implement the function of the mobile node in the method embodiment shown in Figures 4 to 7 above: the transceiver unit 1220 receives the address information assigned to the mobile node from the first SMF, and the address information of the mobile node is public network address information; wherein, the address information of the mobile node is used to establish a user plane tunnel between the mobile node and the first UPF, and the user plane tunnel belongs to the first session between the terminal device accessing the mobile node and the first UPF, the first UPF is the UPF serving the terminal device, and the mobile node is used to provide access services for the terminal device; the processing unit 1210 sends the public network address information to the first UPF through the transceiver unit 1220.

[0317] When the communication device 1200 is used to implement the function of the mobile node in the method embodiment shown in Figure 8 or Figure 9 above: the processing unit 1210 is used to receive the address information assigned to the mobile node from the first SMF through the transceiver unit 1220 during the process of establishing a first session; wherein, the first session is a session of a terminal device accessing the mobile node, and the mobile node is used to provide access services for the terminal device; the processing unit 1210 sends tunnel information and indication information to the first UPF through the transceiver unit 1220, the tunnel information includes the address information of the mobile node and the first tunnel endpoint identifier TEID, and the indication information instructs the first UPF to determine the user plane tunnel according to the TEID in the uplink message; wherein, the first UPF is the UPF serving the terminal device.

[0318] When the communication device 1200 is used to implement the function of the first UPF in the method embodiment shown in Figures 8 or 9 above: the transceiver unit 1220 is used to receive tunnel information and indication information from the mobile node, and the tunnel information includes the address information and the first TEID of the mobile node; the processing unit 1210 is used to determine the user plane tunnel corresponding to the first TEID in the uplink message based on the indication information and the tunnel information in the uplink message when an uplink message is received.

[0319] When the communication device 1200 is used to implement the function of the first UPF in the method embodiment shown in the above-mentioned Figure 10: the transceiver unit 1220 is used to receive a first uplink message from a mobile node, and the first uplink message indicates the correspondence between the private network address information and the public network address information of the mobile node; the processing unit 1210 is used to determine the private network address information corresponding to the source address information according to the source address information in the second uplink message and the correspondence when receiving a second uplink message from the mobile node, and determine the corresponding user plane tunnel according to the private network address information; wherein, the source address information is the public network address information of the mobile node.

[0320] When the communication device 1200 is used to implement the function of the mobile node in the method embodiment shown in the above-mentioned Figure 10: the processing unit 1210 is used to send a first uplink message to the first UPF through the transceiver unit 1220, and the first uplink message indicates the correspondence between the private network address information and the public network address information of the mobile node.

[0321] When the communication device 1200 is used to implement the function of the mobile node in the method embodiment shown in Figure 11 above: the transceiver unit 1220 is used to receive the address information allocated to the mobile node from the first SMF, and the address information is private network address information; the processing unit 1210 is used to send a request message to the server for providing the public network address information service after address conversion through the transceiver unit 1220, and the request message is used to obtain the public network address information after the private network address of the mobile node is converted; the transceiver unit 1220 is used to receive a response message from the server, and the response message includes the public network address information; tunnel information is sent to the first UPF through the transceiver unit 1220, and the tunnel information includes the public network address information. The tunnel information is used to establish a user plane tunnel between the mobile node and the first UPF, and the user plane tunnel belongs to the first session between the terminal device accessing the mobile node and the first UPF, the first UPF is the UPF serving the terminal device, and the mobile node is used to provide access services for the terminal device.

[0322] A more detailed description of the processing unit 1210 and the transceiver unit 1220 can be directly obtained by referring to the relevant description in the method embodiment shown in the above drawings, and is not repeated here.

[0323] As shown in Figure 13, communication device 1300 includes a processor 1310 and an interface circuit 1320. Processor 1310 and interface circuit 1320 are coupled to each other. It is understood that interface circuit 1320 can be a transceiver or an input / output interface. Optionally, communication device 1300 may also include a memory 1330 for storing instructions executed by processor 1310, input data required by processor 1310 to execute instructions, or data generated by processor 1310 after executing instructions.

[0324] When the communication device 1300 is used to implement the method shown in the above figures, the processor 1310 is used to implement the functions of the above processing unit 1210, and the interface circuit 1320 is used to implement the functions of the above transceiver unit 1220.

[0325] When the communication device is a chip implemented in the device, the chip implements the functions of the corresponding device in the method embodiment. The chip receives information from other modules in the device (such as a radio frequency module or antenna), where the information is sent to the device by other modules; or the chip sends information to other modules in the device (such as a radio frequency module or antenna).

[0326] When the above-mentioned communication device is a module applied to a mobile node, the module implements the functions of the mobile node in the above-mentioned method embodiment. The module receives information from other modules (such as a radio frequency module or antenna), and the information is sent by the terminal to the device; or the module sends information to other modules in the device (such as a radio frequency module or antenna), and the information is sent by the device to the terminal. The module here can be the baseband chip of the device, or it can be a DU or other module. The DU here can be a DU under the open radio access network (O-RAN) architecture.

[0327] It is understood that the processor in the embodiments of the present application may be a central processing unit (CPU), or may be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field programmable gate arrays (FPGA), or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. The general-purpose processor may be a microprocessor or any conventional processor.

[0328] This application provides another example of a communication device, which includes at least one processor and at least one memory, the at least one processor and the at least one memory being coupled together, the at least one memory being used to store instructions. When the instructions are executed by the at least one processor, the communication device performs the method in the above-described embodiment. Taking a communication device including a processor and a memory as an example, as shown in FIG13 , a communication device 1300 includes a processor 1310 and a memory 1330. The processor 1310 and the memory 1330 are coupled together, and the memory 1330 stores instructions. When the instructions stored in the memory 1330 are executed by the processor 1310, the communication device 1300 performs the method performed by the terminal device or network device in the above-described embodiment.

[0329] It should be understood that the processor 1310 and the memory 1330 may also be integrated together, such as in one chip.

[0330] The method steps in the embodiments of the present application can be implemented in hardware or in software instructions that can be executed by a processor. The software instructions can be composed of corresponding software modules, and the software modules can be stored in random access memory, flash memory, read-only memory, programmable read-only memory, erasable programmable read-only memory, electrically erasable programmable read-only memory, registers, hard disk, mobile hard disk, CD-ROM or any other form of storage medium well known in the art. An exemplary storage medium is coupled to the processor so that the processor can read information from the storage medium and write information to the storage medium. The storage medium can also be an integral part of the processor. The processor and storage medium can be located in an ASIC. In addition, the ASIC can be located in a network device or a terminal. The processor and storage medium can also exist in a network device or a terminal as discrete components.

[0331] In the above embodiments, all or part of the embodiments may be implemented using software, hardware, firmware, or any combination thereof. When implemented using software, all or part of the embodiments may be implemented in the form of a computer program product. The computer program product includes one or more computer programs or instructions. When the computer program or instructions are loaded and executed on a computer, the processes or functions described in the embodiments of the present application are performed in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, a network device, a user device, or other programmable device. The computer program or instructions may be stored in a computer-readable storage medium or transferred from one computer-readable storage medium to another. For example, the computer program or instructions may be transferred from one website, computer, server, or data center to another website, computer, server, or data center via wired or wireless means. The computer-readable storage medium may be any available medium that can be accessed by a computer or a data storage device such as a server or data center that integrates one or more available media. The available medium may be a magnetic medium, such as a floppy disk, hard disk, or magnetic tape; an optical medium, such as a digital video disk; or a semiconductor medium, such as a solid-state drive. The computer-readable storage medium may be a volatile or nonvolatile storage medium, or may include both volatile and nonvolatile types of storage media.

[0332] In the various embodiments of the present application, unless otherwise specified or there is a logical conflict, the terms and / or descriptions between different embodiments are consistent and can be referenced by each other. The technical features in different embodiments can be combined to form new embodiments according to their inherent logical relationships.

[0333] In this application, "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. In the text description of this application, the character " / " generally indicates that the previous and next associated objects are in an "or" relationship; in the formula of this application, the character " / " indicates that the previous and next associated objects are in a "division" relationship. "Including at least one of A, B and C" can mean: including A; including B; including C; including A and B; including A and C; including B and C; including A, B and C.

[0334] It is understood that the various numbers used in the embodiments of this application are merely for ease of description and are not intended to limit the scope of the embodiments of this application. The order of the sequence numbers of the above-mentioned processes does not necessarily imply a specific order of execution; the order of execution of the processes should be determined by their functions and inherent logic.

Claims

1. A communication method, characterized in that: Applied to a first session management function SMF, the method comprises: Sending address information of the mobile node to the mobile node, where the address information of the mobile node is public network address information; Among them, the address information of the mobile node is used to establish a user plane tunnel between the mobile node and the first user plane function UPF, the user plane tunnel belongs to the first session between the terminal device accessing the mobile node and the first UPF, the first UPF is the UPF serving the terminal device, and the mobile node is used to provide access services for the terminal device.

2. The method according to claim 1, wherein Also includes: receiving a first request message; The first request message is used to request modification of a second session, the second session is used to establish a first backhaul link before the modification, and the second session is used to establish a second backhaul link after the modification; or The first request message is used to request establishment of a third session, and the third session is used to establish the second backhaul link; Among them, the first backhaul link is the backhaul link between the mobile node and the first access and mobility management function AMF, the second backhaul link is the backhaul link between the mobile node and the first UPF, and the first AMF serves the terminal device.

3. The method according to claim 1 or 2, wherein: Also includes: A first response message is sent in response to the first request message, where the first response message includes the address information of the mobile node.

4. The method according to any one of claims 2 to 3, wherein: The first request message includes indication information for indicating a type of the third session, where the indication information indicates that the type of the third session is a session for establishing the second backhaul link.

5. The method according to any one of claims 1 to 4, characterized in that The public network address information is allocated by the first SMF to the mobile node.

6. The method according to any one of claims 1 to 4, characterized in that Before sending the address information of the mobile node to the mobile node, the method further includes: Sending a second request message to the second UPF, where the second request message includes first indication information, where the first indication information instructs the second UPF to allocate public network address information for the mobile node, or instructs the first UPF to allocate private network address information for the mobile node and determine the public network address information corresponding to the private network address information; Receive a second response message from the second UPF, where the second response message includes the public network address information.

7. The method according to any one of claims 1 to 4, characterized in that Before sending the address information of the mobile node to the mobile node, the method further includes: Send a second request message to the second UPF, where the second request message includes the private network address information allocated by the first SMF to the mobile node and second indication information, where the second indication information instructs the second UPF to determine the public network address information corresponding to the private network address information; Receive a second response message from the second UPF, where the second response message includes the public network address information.

8. The method according to any one of claims 1 to 7, wherein: The first request message also includes the address information of the first UPF, or the first request message and the second request message also include the address information of the first UPF; The public network address information is determined based on the address information of the first UPF.

9. The method according to any one of claims 1 to 8, wherein After receiving the first request message, the method further includes: determining to allocate public network address information to the mobile node according to one or more of the following: The subscription information of the mobile node; or The type of the third session; or The data network name DNN and / or single network slice selection auxiliary information S-NSSAI associated with the second session or the third session.

10. A communication method, characterized in that: Applied to a mobile node, the method includes: receiving address information assigned to the mobile node from the first SMF, where the address information of the mobile node is public network address information; wherein the address information of the mobile node is used to establish a user plane tunnel between the mobile node and the first UPF, where the user plane tunnel belongs to a first session between a terminal device accessing the mobile node and the first UPF, the first UPF being the UPF serving the terminal device, and the mobile node being used to provide access services for the terminal device; Send the public network address information to the first UPF.

11. The method according to claim 10, wherein: Also includes: Sending a first request message to the first SMF; The first request message is used to request modification of a second session, the second session is used to establish a first backhaul link before the modification, and the second session is used to establish a second backhaul link after the modification; or The first request message is used to request establishment of a third session, and the third session is used to establish the second backhaul link; The first backhaul link is a backhaul link between the mobile node and the first AMF, the second backhaul link is a backhaul link between the mobile node and the first UPF, and the first AMF serves the terminal device.

12. The method according to claim 11, wherein The first request message includes indication information for indicating a type of the third session, where the indication information indicates that the type of the third session is a session for establishing the second backhaul link.

13. The method according to any one of claims 11 to 12, wherein: The first request message includes the address information of the first UPF, and the public network address information is determined based on the address information of the first UPF.

14. The method according to any one of claims 11 to 13, wherein: The receiving, from the first SMF, address information allocated to the mobile node, comprises: A first response message is received from the first SMF in response to the first request message, where the first response message includes the address information of the mobile node.

15. A communication method, characterized in that: Applied to a mobile node, the method includes: In the process of establishing a first session, receiving address information allocated to the mobile node from the first SMF; wherein the first session is a session of a terminal device accessing the mobile node, and the mobile node is used to provide access services for the terminal device; Send tunnel information and indication information to the first UPF, the tunnel information including the address information of the mobile node and the first tunnel endpoint identifier TEID, the indication information instructs the first UPF to determine the user plane tunnel based on the TEID in the uplink message; wherein, the first UPF is the UPF serving the terminal device.

16. The method according to claim 15, wherein Before receiving the address information allocated to the mobile node from the first SMF, the method further includes: A first request message is sent to the first SMF, where the first request message is used to obtain the address information of the mobile node, where the address information of the mobile node is used to establish a user plane tunnel between the mobile node and the first UPF, and the user plane tunnel belongs to the first session.

17. The method according to claim 16, wherein Before sending the first request message to the first SMF, the method further includes: receiving the address information and the second TEID of the first UPF; The sending the tunnel information and the instruction information to the first UPF includes: According to the address information of the first UPF and the second TEID, a user plane message is sent to the first UPF, where the user plane message includes the tunnel information and the indication information.

18. The method according to any one of claims 15 to 17, wherein: The first TEID is allocated by the mobile node.

19. A communication method, characterized in that: Applied to a first UPF, where the first UPF is a UPF serving a terminal device accessing a mobile node, the method includes: receiving tunnel information and indication information from the mobile node, wherein the tunnel information includes address information of the mobile node and a first tunnel endpoint identifier (TEID); When an uplink message is received, a user plane tunnel corresponding to the first TEID in the uplink message is determined according to the indication information, based on the first TEID in the uplink message and the tunnel information.

20. A communication method, characterized in that: Applied to the first UPF, the method comprises: receiving a first uplink message from a mobile node, where the first uplink message indicates a correspondence between private network address information and public network address information of the mobile node; When a second uplink message is received from the mobile node, the private network address information corresponding to the source address information is determined based on the source address information in the second uplink message and the corresponding relationship, and the corresponding user plane tunnel is determined based on the private network address information; wherein, the source address information is the public network address information of the mobile node.

21. The method according to claim 20, wherein The message header of the first uplink message includes the private network address information of the mobile node, and the payload of the first uplink message includes source address information, which is converted from the private network address information of the mobile node to public network address information.

22. The method according to claim 20 or 21, wherein: Before receiving the first uplink message from the mobile node, the method further includes: receiving tunnel information from the mobile node, the tunnel information including address information of the mobile node, the address information of the mobile node being private network address information, the tunnel information being used to establish a user plane tunnel between the mobile node and the first UPF, the user plane tunnel belonging to a first session between a terminal device accessing the mobile node and the first UPF, the first UPF being a UPF serving the terminal device, and the mobile node being used to provide access services for the terminal device; The determining the corresponding user plane tunnel according to the private network address information includes: Determine a corresponding user plane tunnel according to the private network address information and the tunnel information.

23. A communication method, characterized in that: Applied to a mobile node, the method includes: A first uplink message is sent to the first UPF, where the first uplink message indicates a correspondence between the private network address information and the public network address information of the mobile node.

24. The method according to claim 23, wherein The message header of the first uplink message includes the private network address information of the mobile node, and the payload of the first uplink message includes source address information, which is converted from the private network address information of the mobile node to public network address information.

25. The method according to claim 23 or 24, wherein: Before sending the first uplink message to the first UPF, the method further includes: Tunnel information is sent to the first UPF, where the tunnel information includes the address information of the mobile node, where the address information of the mobile node is private network address information. The tunnel information is used to establish a user plane tunnel between the mobile node and the first UPF, where the user plane tunnel belongs to the first session between the terminal device accessing the mobile node and the first UPF. The first UPF is the UPF serving the terminal device, and the mobile node is used to provide access services for the terminal device.

26. A communication method, characterized in that: Applied to a mobile node, the method includes: receiving, from the first SMF, address information allocated to the mobile node, where the address information is private network address information; Sending a request message to a server for providing a public network address information service after address conversion, wherein the request message is used to obtain the public network address information after the private network address of the mobile node is converted; receiving a response message from the server, wherein the response message includes the public network address information; Tunnel information is sent to the first UPF, where the tunnel information includes the public network address information. The tunnel information is used to establish a user plane tunnel between the mobile node and the first UPF. The user plane tunnel belongs to the first session between the terminal device accessing the mobile node and the first UPF. The first UPF is the UPF serving the terminal device, and the mobile node is used to provide access services for the terminal device.

27. The method according to claim 26, wherein The mobile node is configured as an Address Translated User Datagram Protocol Simple Traversal (STUN) client, and the server is configured as a STUN server.

28. A communication device, characterized in that: The method comprises a unit or module for executing the method according to any one of claims 1 to 9, or a unit or module for executing the method according to any one of claims 10 to 14, or a unit or module for executing the method according to any one of claims 15 to 18, or a unit or module for executing the method according to claim 19, or a unit or module for executing the method according to any one of claims 20 to 22, or a unit or module for executing the method according to any one of claims 23 to 25, or a unit or module for executing the method according to any one of claims 26 to 27.

29. A communication device, characterized in that: include: One or more processors are configured to perform the method of any one of claims 1-9, or to perform the method of any one of claims 10-14, or to perform the method of any one of claims 15-18, or to perform the method of claim 19, or to perform the method of any one of claims 20-22, or to perform the method of any one of claims 23-25, or to perform the method of any one of claims 26-27.

30. A readable storage medium, characterized in that The readable storage medium stores a program or instruction, which, when executed on a device, causes the device to execute the method according to any one of claims 1 to 9, or the method according to any one of claims 10 to 14, or the method according to any one of claims 15 to 18, or the method according to claim 19, or the method according to any one of claims 20 to 22, or the method according to any one of claims 23 to 25, or the method according to any one of claims 26 to 27.

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