Communication method, communication device and communication system

Abstract

The invention provides a communication method, a communication device and a communication system. The method comprises the following steps: receiving a first message from a first mobility management network element, wherein the first message comprises identification information of a second mobility management network element; sending the identification information of the second mobility management network element to an access network device; wherein the terminal device and the access network device form a vehicle-mounted relay device, the first mobility management network element is a mobility management network element registered by the terminal device, and the second mobility management network element is a mobility management network element accessed by the access network device through a wireless backhaul link. As the vehicle-mounted relay access network equipment can receive the identification information of the second mobility management network element, the vehicle-mounted relay access network equipment accesses the second mobility management network element through the wireless backhaul link, and the proper mobility management network element for wireless backhaul link access is allocated to the vehicle-mounted relay access network equipment.

Description

Technical Field

[0001] The present application relates to the field of wireless communication technology, and in particular to a communication method, a communication device and a communication system. Background Art

[0002] At present, vehicle mounted relay (VMR) equipment is proposed based on vehicle-mounted scenarios. VMR equipment is usually deployed on a moving vehicle and consists of an access network device and a terminal device, the terminal device can be called a VMR terminal device, and the access network device can be called a VMR access network device.

[0003] Since the vehicle moves, the VMR access network equipment and VMR terminal equipment also have mobility. Among them, the VMR terminal equipment has the functions of ordinary terminal equipment and can access the core network through the new radio (NR). Usually, the N2 backhaul link between the ground access network equipment that is fixed on the ground and the core network can be realized through optical fiber. The N2 backhaul link between the mobile VMR access network equipment and the core network can be carried on the protocol data unit (PDU) session between the VMR terminal equipment and the core network to realize wireless backhaul, so that the VMR access network equipment can provide wireless access for other terminal devices near the vehicle.

[0004] The VMR access network device communicates with the mobility management network element of the core network through the N2 backhaul link, but how to select a suitable mobility management network element for the VMR access network device to access the N2 wireless backhaul link remains to be solved. Summary of the invention

[0005] The embodiments of the present application provide a communication method, a communication device and a communication system for selecting a suitable mobility management network element for N2 wireless backhaul link access for a vehicle-mounted relay access network device.

[0006] In a first aspect, an embodiment of the present application provides a communication method, which can be executed by a terminal device or a module (such as a chip) in the terminal device. The method includes: receiving a first message from a first mobility management network element, the first message including identification information of a second mobility management network element; sending identification information of the second mobility management network element to an access network device; wherein the terminal device and the access network device constitute a vehicle-mounted relay device, the first mobility management network element is a mobility management network element registered by the terminal device, and the second mobility management network element is a mobility management network element accessed by the access network device through a wireless backhaul link.

[0007] In the above scheme, the vehicle-mounted relay access network device can receive the identification information of the second mobility management network element, and the vehicle-mounted relay access network device accesses the second mobility management network element through the wireless backhaul link, thereby allocating a suitable mobility management network element for accessing the wireless backhaul link to the vehicle-mounted relay access network device.

[0008] In a possible implementation method, before receiving the first message from the first mobility management network element, the method further includes: sending a NAS request message to the first mobility management network element; and the first message is a NAS response message.

[0009] In the above solution, the identification information of the second mobility management network element is carried in the NAS response message, and there is no need to carry the identification information of the second mobility management network element through additional signaling, which can reduce signaling overhead.

[0010] In a possible implementation method, the NAS request message includes first indication information, and the first indication information is used to indicate at least one of the following: the type of the terminal device, the type indicating that the terminal device is a vehicle-mounted relay terminal device jointly installed with the access network device; the capability of the terminal device, the capability being that the terminal device has the ability to establish a wireless backhaul link using a PDU session; and identification information of a mobility management network element requested to be accessed through the wireless backhaul link.

[0011] In the above solution, the identification information of the mobility management network element is determined for the access network device by triggering the first indication information, so that the identification information of the mobility management network element is determined for the access network device quickly.

[0012] In a possible implementation method, the method further includes: receiving a session establishment acceptance message, the session establishment acceptance message including address information of the terminal device; and sending the address information of the terminal device to the access network device.

[0013] In the above solution, the address information of the terminal device is carried in the session establishment acceptance message, and there is no need to add additional signaling to carry the address information of the terminal device, which can reduce signaling overhead.

[0014] In a possible implementation method, before receiving the first message from the first mobility management network element, it also includes: sending a session establishment request message to the first mobility management network element, the session establishment request message including identification information of the PDU session; then the first message is a session establishment acceptance message.

[0015] In the above solution, the identification information of the second mobility management network element is carried in the session establishment accept message, and there is no need to carry the identification information of the second mobility management network element through additional signaling, which can reduce signaling overhead.

[0016] In a possible implementation method, the session establishment request message also includes second indication information, and the second indication information is used to indicate that the PDU session is used to establish a wireless backhaul link.

[0017] In the above solution, the identification information of the mobility management network element is determined for the access network device by triggering the second indication information, so that the identification information of the mobility management network element is determined for the access network device quickly.

[0018] In a possible implementation method, the session establishment acceptance message also includes address information of the terminal device; the method further includes: sending the address information of the terminal device to the access network device.

[0019] In the above solution, the address information of the terminal device is carried in the session establishment acceptance message, and there is no need to add additional signaling to carry the address information of the terminal device, which can reduce signaling overhead.

[0020] In a possible implementation method, the second mobility management network element and the first mobility management network element are the same mobility management network element.

[0021] In a possible implementation method, the second mobility management network element and the first mobility management network element are different mobility management network elements, and the first message further includes a service area of ​​the second mobility management network element.

[0022] In a possible implementation method, the method also includes: receiving a second message, the second message including identification information of a third mobility management network element; sending identification information of the third mobility management network element to the access network device, the third mobility management network element being a mobility management network element accessed by the access network device through a wireless backhaul link or a mobility management network element newly registered for the terminal device.

[0023] The above solution can update the identification information of the mobility management network element for the access network device, and can ensure that the access network device can access the correct mobility management network element.

[0024] In a possible implementation method, the second message is a configuration update message or a session modification message.

[0025] In a second aspect, an embodiment of the present application provides a communication method, which can be executed by a first mobility management network element or a module (such as a chip) in the first mobility management network element. The method includes: obtaining identification information of a second mobility management network element; sending a first message to a terminal device, the first message including identification information of the second mobility management network element; wherein the terminal device and the access network device constitute a vehicle-mounted relay device, the first mobility management network element is a mobility management network element registered by the terminal device, and the second mobility management network element is a mobility management network element accessed by the access network device through a wireless backhaul link.

[0026] In the above scheme, the terminal device can receive the identification information of the second mobility management network element, so that the terminal device can send the identification information of the second mobility management network element to the vehicle-mounted access network device. The vehicle-mounted relay access network device accesses the second mobility management network element through the wireless backhaul link, thereby allocating a suitable mobility management network element for wireless backhaul link access to the vehicle-mounted relay access network device.

[0027] In a possible implementation method, before obtaining the identification information of the second mobility management network element, it also includes: receiving a NAS request message from the terminal device; then the first message is a NAS response message.

[0028] In the above solution, the identification information of the second mobility management network element is carried in the NAS response message, and there is no need to carry the identification information of the second mobility management network element through additional signaling, which can reduce signaling overhead.

[0029] In a possible implementation method, the NAS request message includes first indication information; the obtaining of identification information of the second mobility management network element includes: obtaining identification information of the second mobility management network element according to the first indication information; wherein the first indication information is used to indicate at least one of the following: the type of the terminal device, the type indicating that the terminal device is a vehicle-mounted relay terminal device jointly set up with the access network device; the capability of the terminal device, the capability being that the terminal device has the ability to establish a wireless backhaul link using a protocol data unit PDU session; and the identification information of the mobility management network element requested to be accessed through the wireless backhaul link.

[0030] In the above solution, the identification information of the mobility management network element is determined for the access network device by triggering the first indication information, so that the identification information of the mobility management network element is determined for the access network device quickly.

[0031] In a possible implementation method, the method also includes: receiving first indication information from a data management network element; the obtaining of identification information of a second mobility management network element includes: obtaining identification information of the second mobility management network element according to the first indication information; wherein the first indication information is used to indicate at least one of the following: the type of the terminal device, the type indicating that the terminal device is a vehicle-mounted relay terminal device jointly provided with the access network device; the capability of the terminal device, the capability being that the terminal device has the ability to establish a wireless backhaul link using a protocol data unit PDU session.

[0032] In the above solution, the identification information of the mobility management network element is determined for the access network device by triggering the first indication information, so that the identification information of the mobility management network element is determined for the access network device quickly.

[0033] In a possible implementation method, the method further includes: sending a session establishment acceptance message to the terminal device, wherein the session establishment acceptance message includes address information of the terminal device.

[0034] In the above solution, the address information of the terminal device is carried in the session establishment acceptance message, and there is no need to add additional signaling to carry the address information of the terminal device, which can reduce signaling overhead.

[0035] In a possible implementation method, before obtaining the identification information of the second mobility management network element, it also includes: receiving a session establishment request message from the terminal device, the session establishment request message including the identification information of the PDU session; then the first message is a session establishment acceptance message.

[0036] In the above solution, the identification information of the second mobility management network element is carried in the session establishment accept message, and there is no need to carry the identification information of the second mobility management network element through additional signaling, which can reduce signaling overhead.

[0037] In a possible implementation method, the session establishment request message also includes second indication information, and the second indication information is used to indicate that the PDU session is used to establish a wireless backhaul link; obtaining the identification information of the second mobility management network element includes: obtaining the identification information of the second mobility management network element according to the second indication information.

[0038] In the above solution, the identification information of the mobility management network element is determined for the access network device by triggering the second indication information, so that the identification information of the mobility management network element is determined for the access network device quickly.

[0039] In a possible implementation method, the session establishment acceptance message further includes address information of the terminal device.

[0040] In the above solution, the address information of the terminal device is carried in the session establishment acceptance message, and there is no need to add additional signaling to carry the address information of the terminal device, which can reduce signaling overhead.

[0041] In a possible implementation method, the second mobility management network element and the first mobility management network element are the same mobility management network element.

[0042] In one possible implementation method, obtaining the identification information of the second mobility management network element includes: sending a query request to a network storage function network element, the query request including the location information of the terminal device, and the query request is used to query the identification information of the mobility management network element that can be accessed through the wireless backhaul link; receiving a query response from the network storage function network element, the query response including the identification information of the second mobility management network element.

[0043] The above scheme, by sending a query request to the network storage function network element, can accurately obtain the identification information of the mobility management network element that provides N2 return link access to the access network device from the network storage function network element, thereby better providing N2 return link access service to the access network device.

[0044] In a possible implementation method, the first message also includes a service area of ​​the second mobility management network element.

[0045] In a possible implementation method, the method also includes: sending a configuration update message to the terminal device, the configuration update message including identification information of a third mobility management network element, the third mobility management network element being a mobility management network element accessed by the access network device through a wireless backhaul link or a mobility management network element newly registered for the terminal device.

[0046] The above solution can update the identification information of the mobility management network element for the access network device, and can ensure that the access network device can access the correct mobility management network element.

[0047] In a third aspect, an embodiment of the present application provides a communication method, which can be executed by a first mobility management network element or a module (such as a chip) in the first mobility management network element. The method includes: sending a query request to a network storage function network element, the query request includes the location information of a terminal device, and the query request is used to query the identification information of a mobility management network element that can be accessed through a wireless backhaul link; receiving a query response from the network storage function network element, the query response includes the identification information of a second mobility management network element, the terminal device and the access network device constitute a vehicle-mounted relay device, and the second mobility management network element is a mobility management network element that the access network device accesses through a wireless backhaul link.

[0048] In a fourth aspect, an embodiment of the present application provides a communication method, which can be executed by a session management network element or a module (such as a chip) in the session management network element. The method includes: receiving identification information of a second mobility management network element from a first mobility management network element; sending identification information of the second mobility management network element to a terminal device; wherein the terminal device and the access network device constitute a vehicle-mounted relay device, the first mobility management network element is a mobility management network element registered by the terminal device, and the second mobility management network element is a mobility management network element accessed by the access network device through a wireless backhaul link.

[0049] In the above scheme, the terminal device can receive the identification information of the second mobility management network element, so that the terminal device can send the identification information of the second mobility management network element to the vehicle-mounted access network device. The vehicle-mounted relay access network device accesses the second mobility management network element through the wireless backhaul link, thereby allocating a suitable mobility management network element for wireless backhaul link access to the vehicle-mounted relay access network device.

[0050] In a possible implementation method, the receiving identification information of the second mobility management network element from the first mobility management network element includes: receiving a session context establishment request message from the first mobility management network element, the session context establishment request message including the identification information of the second mobility management network element; the sending the identification information of the second mobility management network element to the terminal device includes: sending a session establishment acceptance message to the terminal device, the session establishment acceptance message including the identification information of the second mobility management network element.

[0051] In a possible implementation method, the session establishment acceptance message further includes address information of the terminal device and / or a service area of ​​the second mobility management network element.

[0052] In a possible implementation method, the method also includes: sending a session modification message to the terminal device, the session modification message including identification information of a third mobility management network element, the third mobility management network element being a mobility management network element accessed by the access network device through a wireless backhaul link or a mobility management network element newly registered for the terminal device.

[0053] The above solution can update the identification information of the mobility management network element for the access network device, and can ensure that the access network device can access the correct mobility management network element.

[0054] In a possible implementation method, the second mobility management network element and the first mobility management network element are the same mobility management network element.

[0055] In a fifth aspect, an embodiment of the present application provides a communication method, which can be executed by a vehicle-mounted relay device or a module (such as a chip) in the vehicle-mounted relay device. The method includes: receiving a first message from a first mobility management network element, the first message including identification information of a second mobility management network element; accessing the second mobility management network element through a protocol data unit PDU session; wherein the first mobility management network element is the mobility management network element registered by the vehicle-mounted relay device.

[0056] In the above scheme, the vehicle-mounted relay device can receive the identification information of the second mobility management network element, and the vehicle-mounted relay device accesses the second mobility management network element through the wireless backhaul link, thereby allocating a suitable mobility management network element for the vehicle-mounted relay device to access the wireless backhaul link.

[0057] In a possible implementation method, before receiving the first message from the first mobility management network element, the method further includes: sending a NAS request message to the first mobility management network element; and the first message is a NAS response message.

[0058] In the above solution, the identification information of the second mobility management network element is carried in the NAS response message, and there is no need to carry the identification information of the second mobility management network element through additional signaling, which can reduce signaling overhead.

[0059] In a possible implementation method, the NAS request message includes first indication information, and the first indication information is used to indicate at least one of the following: the type of the vehicle-mounted relay device, the type indicating that the vehicle-mounted terminal device is equipped with a vehicle-mounted terminal device and a vehicle-mounted access network device; the capability of the vehicle-mounted relay device, the capability indicating that the vehicle-mounted relay device has the ability to establish a wireless backhaul link using a PDU session; and the identification information of the mobility management network element requested to be accessed through the wireless backhaul link.

[0060] In the above solution, the identification information of the mobility management network element is determined for the access network device by triggering the first indication information, so that the identification information of the mobility management network element is determined for the access network device quickly.

[0061] In a possible implementation method, the method further includes: receiving a session establishment acceptance message, wherein the session establishment acceptance message includes address information of the vehicle-mounted relay device.

[0062] In the above solution, the address information of the vehicle-mounted relay device is carried in the session establishment acceptance message, and there is no need to carry the address information of the vehicle-mounted relay device through additional signaling, which can reduce signaling overhead.

[0063] In a possible implementation method, before receiving the first message from the first mobility management network element, it also includes: sending a session establishment request message to the first mobility management network element, the session establishment request message including identification information of the PDU session; then the first message is a session establishment acceptance message.

[0064] In the above solution, the identification information of the second mobility management network element is carried in the session establishment accept message, and there is no need to carry the identification information of the second mobility management network element through additional signaling, which can reduce signaling overhead.

[0065] In a possible implementation method, the session establishment request message also includes second indication information, and the second indication information is used to indicate that the PDU session is used to establish a wireless backhaul link.

[0066] In the above solution, the identification information of the mobility management network element is determined for the access network device by triggering the second indication information, so that the identification information of the mobility management network element is determined for the access network device quickly.

[0067] In a possible implementation method, the session establishment acceptance message also includes address information of the vehicle-mounted relay device.

[0068] In the above solution, the address information of the terminal device is carried in the session establishment acceptance message, and there is no need to add additional signaling to carry the address information of the terminal device, which can reduce signaling overhead.

[0069] In a possible implementation method, the second mobility management network element and the first mobility management network element are the same mobility management network element.

[0070] In a possible implementation method, the second mobility management network element and the first mobility management network element are different mobility management network elements, and the first message further includes a service area of ​​the second mobility management network element.

[0071] In a possible implementation method, the method also includes: receiving a second message, the second message including identification information of a third mobility management network element, the third mobility management network element being a mobility management network element accessed by the access network device through a wireless backhaul link or a mobility management network element newly registered for the terminal device.

[0072] The above solution can update the identification information of the mobility management network element for the access network device, and can ensure that the access network device can access the correct mobility management network element.

[0073] In a possible implementation method, the method also includes: before receiving the second message, determining that the vehicle-mounted relay device has moved out of the service area of ​​the second mobility management network element, and sending a configuration update request message to the second mobility management network element, the configuration update request message including the location information of the vehicle-mounted relay device, and the configuration update request message is used to request the discovery of the mobility management network element.

[0074] In a possible implementation method, the configuration update request message further includes third indication information, and the third indication information is used to request discovery of a mobility management network element.

[0075] In a possible implementation method, the second message is a configuration update message or a session modification message.

[0076] In a sixth aspect, an embodiment of the present application provides a communication device, which may be a terminal device or a module (such as a chip) in a terminal device. The device has the function of implementing any implementation method of the first aspect above. The function may be implemented by hardware or by executing corresponding software implementation by hardware. The hardware or software includes one or more modules corresponding to the above functions.

[0077] In a seventh aspect, an embodiment of the present application provides a communication device, which may be a first mobility management network element, or a module (such as a chip) in the first mobility management network element. The device has the function of implementing any implementation method of the second aspect or the third aspect above. The function may be implemented by hardware, or may be implemented by hardware executing corresponding software. The hardware or software includes one or more modules corresponding to the above functions.

[0078] In an eighth aspect, an embodiment of the present application provides a communication device, which may be a session management network element, or a module (such as a chip) in a session management network element. The device has the function of implementing any implementation method of the fourth aspect above. The function may be implemented by hardware, or by hardware executing corresponding software implementation. The hardware or software includes one or more modules corresponding to the above functions.

[0079] In the ninth aspect, an embodiment of the present application provides a communication device, which may be a vehicle-mounted relay device, or a module (such as a chip) in a vehicle-mounted relay device. The device has the function of implementing any implementation method of the fifth aspect above. The function may be implemented by hardware, or by hardware executing corresponding software implementation. The hardware or software includes one or more modules corresponding to the above functions.

[0080] In a tenth aspect, an embodiment of the present application provides a communication device, comprising a unit or means for executing each step of any implementation method in the first to fifth aspects above.

[0081] In an eleventh aspect, an embodiment of the present application provides a communication device, including a processor and an interface circuit, wherein the processor is used to communicate with other devices through the interface circuit and execute any implementation method in the first to fifth aspects above. The processor includes one or more.

[0082] Optionally, the communication device may further include a memory for storing computer instructions, the memory being coupled to a processor, and the processor executing the computer instructions stored in the memory so that the device executes any implementation method in the first to fifth aspects above.

[0083] In the twelfth aspect, an embodiment of the present application further provides a computer program product, which includes a computer program or instructions. When the computer program or instructions are executed by a communication device, any implementation method in the above-mentioned first to fifth aspects is executed.

[0084] In the thirteenth aspect, an embodiment of the present application further provides a computer-readable storage medium, wherein instructions are stored in the computer-readable storage medium, which, when executed on a communication device, enables any implementation method in the above-mentioned first to fifth aspects to be executed.

[0085] In the fourteenth aspect, an embodiment of the present application also provides a chip system, including: a processor, used to execute any implementation method in the above-mentioned first to fifth aspects.

[0086] In a fifteenth aspect, an embodiment of the present application further provides a communication system, comprising a terminal device for executing any implementation method of the first aspect, and an access network device for receiving identification information of a second mobility management network element from the terminal device.

[0087] In a possible implementation method, the communication system also includes a first mobility management network element for executing any implementation method of the third aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0088] Figure 1(a) is a schematic diagram of a 5G network architecture based on a service-oriented architecture;

[0089] Figure 1(b) is a schematic diagram of a 5G network architecture based on a point-to-point interface;

[0090] Figure 2 is a schematic diagram of TA;

[0091] Figure 3 It is a schematic diagram of the basic architecture of VMR;

[0092] Figure 4 Schematic diagram of forwarding N2 messages between VMR-gNB and AMF through PDU session;

[0093] Figure 5(a) to Figure 5(b) A flow chart of a communication method provided in an embodiment of the present application;

[0094] Figure 6 to Figure 9 A flow chart of a communication method provided in an embodiment of the present application;

[0095] Fig.10 It is a schematic diagram of the movement of VMR;

[0096] Figure 11-12 A flow chart of a communication method provided in an embodiment of the present application;

[0097] Fig.13 A schematic diagram of the structure of a communication device provided in an embodiment of the present application;

[0098] Fig.14 A schematic diagram of the structure of a communication device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0099] In order to meet the challenges of wireless broadband technology and maintain the leading edge of the 3rd Generation Partnership Project (3GPP) network, the 3GPP standards group has developed the next generation mobile communication network system (Next Generation System) architecture, called the 5G network architecture. This architecture not only supports the access to the 5G core network (CN) of the wireless access technology defined by the 3GPP standards group (such as long term evolution (LTE) access technology, 5G radio access network (RAN) access technology, etc.), but also supports the use of non-3GPP (non-3GPP) access technology through the non-3GPP interworking function (N3IWF) or the next generation access gateway (next generation packet data gateway, ngPDG) to access the core network.

[0100] Figure 1(a) is a schematic diagram of a 5G network architecture based on a service-oriented architecture. The 5G network architecture shown in Figure 1(a) may include access network equipment and core network equipment. The terminal device accesses the data network (DN) through the access network equipment and the 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 (not shown in the figure), unified data management (UDM) network element, unified data repository (UDR) network element, network storage function (NRF) network element (not shown in the figure), network exposure function (NEF) network element (not shown in the figure), 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, user plane function (UPF) network element, binding support function (BSF) network element (not shown in the figure).

[0101] The terminal device can be a user equipment (UE), a mobile station, a mobile terminal device, etc. The terminal device 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 wearable, smart transportation, smart city, etc. The terminal device can be a mobile phone, a tablet computer, a computer with wireless transceiver function, a wearable device, a vehicle, an urban air vehicle (such as a drone, a helicopter, etc.), a ship, a robot, a robotic arm, a smart home device, etc.

[0102] The access network equipment may be a radio access network (RAN) equipment or a wireline access network (FAN) equipment. Among them, the radio access network equipment includes 3GPP access network equipment, untrusted non-3GPP access network equipment and trusted non-3GPP access network equipment. 3GPP access network equipment includes but is not limited to: evolved NodeB (eNodeB) in LTE, next generation NodeB (gNB) in 5G mobile communication system, base station in future mobile communication system or module or unit that completes part of the functions of base station, such as centralized unit (CU), distributed unit (DU), etc. Untrusted non-3GPP access network equipment includes but is not limited to: untrusted non-3GPP access gateway or N3IWF equipment, untrusted wireless local area network (WLAN) access point (AP), switch, router. Trusted non-3GPP access network equipment includes but is not limited to: trusted non-3GPP access gateway, trusted WLAN AP, switch, router. Wired access network equipment includes but is not limited to: wireline access gateway, fixed telephone network equipment, switches, and routers.

[0103] The access network equipment and terminal equipment can be fixed or movable. The access network equipment and terminal equipment can be deployed on land, including indoors or outdoors, handheld or vehicle-mounted; they can also be deployed on the water surface; they can also be deployed on airplanes, balloons and artificial satellites in the air. The embodiments of the present application do not limit the application scenarios of the access network equipment and terminal equipment.

[0104] The AMF network element is responsible for UE mobility management, including mobile state management, allocating temporary identities to UEs, and authenticating and authorizing UEs.

[0105] 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.

[0106] UPF network element supports all or part of the following functions: interconnecting protocol data unit (PDU) sessions with data networks; packet routing and forwarding (for example, supporting uplink classification of traffic (Uplink classifier) ​​and forwarding to the data network); data packet detection.

[0107] The UDM network element is responsible for managing contract data and notifying the corresponding network element when the contract data is modified.

[0108] UDR network elements store and retrieve contract data, policy data, and public architecture data, etc.; they provide UDM network elements, PCF network elements, and NEF network elements with access to relevant data. UDR network elements must be able to have different data access authentication mechanisms for different types of data, such as contract data and policy data, to ensure the security of data access; UDR network elements must be able to return a failure response with an appropriate reason value for illegal service operations or data access requests.

[0109] NEF network element is used to support the opening of capabilities and events.

[0110] AF network elements transmit the requirements of the application side to the network side, such as QoS requirements or user status event subscriptions. AF can be a third-party functional entity or an application service deployed by an operator, such as IP Multimedia Subsystem (IMS) voice call service. Among them, AF network elements include AF network elements in the core network (i.e., AF network elements of operators) and third-party AF network elements (such as an enterprise's application server).

[0111] The PCF network element includes policy control functions such as billing for sessions and service flow levels, QoS bandwidth guarantee and mobility management, and terminal device policy decision-making. PCF network elements include access and mobility management policy control function (AM PCF) network elements and session management policy control function (SM PCF) network elements. Among them, the AM PCF network element is used to formulate AM policies for terminal devices, and the AM PCF network element can also be called a policy control network element that provides services for terminal devices (PCF for a UE). The SM PCF network element is used to formulate session management policies (session management policies, SM policies) for sessions, and the SM PCF network element can also be called a policy control network element that provides services for sessions (PCF for a PDU session).

[0112] NRF network elements can be used to provide network element discovery functions and provide network element information corresponding to the network element type based on requests from other network elements. NRF also provides network element management services, such as network element registration, update, deregistration, and network element status subscription and push.

[0113] BSF network element can provide BSF service registration / deregistration / update, NRF connection detection, session binding information creation, UE information acquisition, IP address duplicate session binding information query and other functions.

[0114] The AUSF network element is responsible for authenticating the UE to determine whether the UE is allowed to access the network.

[0115] DN is a network outside the operator network. The operator network can access multiple DNs. Multiple services can be deployed on DN, which can provide data and / or voice services to terminal devices. For example, DN is the private network of a smart factory. The sensors installed in the workshop of the smart factory can be terminal devices. The control server of the sensors is deployed in DN, and the control server can provide services for the sensors. The sensors can communicate with the control server, obtain instructions from the control server, and transmit the collected sensor data to the control server according to the instructions. For another example, DN is the internal office network of a company. The mobile phones or computers of the company's employees can be terminal devices. The employees' mobile phones or computers can access information and data resources on the company's internal office network.

[0116] In Figure 1(a), Npcf, Nufr, Nudm, Naf, Namf, and Nsmf are service-oriented interfaces provided by the above PCF, UDR, UDM, AF, AMF, and SMF, respectively, for invoking corresponding service-oriented operations. N1, N2, N3, N4, and N6 are interface serial numbers, and the meanings of these interface serial numbers are as follows:

[0117] 1) N1: The interface between AMF and terminal devices, which can be used to transmit non-access stratum (NAS) signaling (such as QoS rules from AMF) to terminal devices.

[0118] 2) N2: The interface between AMF and access network equipment, which can be used to transmit wireless bearer control information from the core network side to the access network equipment.

[0119] 3) 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.

[0120] 4) 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 on the user plane.

[0121] 5) N6: The interface between UPF and DN, used to transfer the uplink and downlink user data flows between UPF and DN.

[0122] Figure 1(b) is a schematic diagram of a 5G network architecture based on a point-to-point interface. The functions of the network elements therein can be referred to the functions of the corresponding network elements in Figure 1(a), and will not be repeated here. The main difference between Figure 1(b) and Figure 1(a) is that the interface between the control plane network elements in Figure 1(a) is a service-oriented interface, while the interface between the control plane network elements in Figure 1(b) is a point-to-point interface.

[0123] In the architecture shown in Figure 1(b), the interface names and functions between the network elements are as follows:

[0124] 1) For the meanings of the N1, N2, N3, N4 and N6 interfaces, please refer to the above description.

[0125] 2) N5: The interface between the AF network element and the PCF network element, which can be used to send application service requests and report network events.

[0126] 3) N7: The interface between PCF network element and SMF network element, which can be used to send PDU session granularity and service data flow granularity control strategy.

[0127] 4) N8: The interface between the AMF network element and the UDM network element, which can be used by the AMF network element to obtain access and mobility management-related contract data and authentication data from the UDM network element, and the AMF network element to register terminal device mobility management-related information with the UDM network element.

[0128] 5) N9: User plane interface between UPF network elements, used to transmit uplink and downlink user data flows between UPF network elements.

[0129] 6) N10: The interface between SMF network element and UDM network element, which can be used by SMF network element to obtain session management related contract data from UDM network element, and SMF network element to register terminal device session related information with UDM network element.

[0130] 7) N11: The interface between the SMF network element and the AMF network element, which can be used to transmit PDU session tunnel information between the access network device and the UPF, transmit control messages sent to the terminal device, transmit wireless resource control information sent to the access network device, etc.

[0131] 8) N15: The interface between the PCF network element and the AMF network element, which can be used to issue terminal device policies and access control related policies.

[0132] 9) N35: The interface between the UDM network element and the UDR network element, which can be used by the UDM network element to obtain user contract data information from the UDR network element.

[0133] 10) N36: The interface between the PCF network element and the UDR network element, which can be used by the PCF network element to obtain policy-related contract data and application data-related information from the UDR network element.

[0134] It is understandable that the above 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 network element or function can be implemented by one device, or by multiple devices, or a functional module in one device, which is not specifically limited in the embodiments of the present application.

[0135] 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 with the functions of the above-mentioned AMF network element, SMF network element, UDM network element, and NRF network element in future communications such as 6G networks, and this application is not limited to this. In the embodiments of the present application, an example is described in which the AMF network element, SMF network element, UDM network element, and NRF network element are respectively the mobility management network element, the session management network element, the data management network element, and the network storage function network element. In addition, the AMF network element, the SMF network element, the UDM network element, and the NRF network element are referred to as AMF, SMF, UDM, and NRF, respectively.

[0136] For ease of explanation, the embodiments of the present application are described using a base station and a UE as a specific example of an access network device and a terminal device, respectively. Any base station and UE appearing in any subsequent position may be replaced by an access network device and a terminal device, respectively.

[0137] To facilitate understanding of the content of this application, the relevant background involved in the embodiments of this application is first introduced below.

[0138] refer to Figure 2, is a schematic diagram of a tracking area (TA). TA is a concept set by 3GPP for UE location management. One TA corresponds to one tracking area code (TAC). Each TA has a unique identifier, namely the tracking area identity (TAI), which consists of a TAC, a mobile country code (MCC) and a mobile network code (MNC). Multiple TAs can form a tracking area list (TAL). According to the coverage range of the antenna, each base station can be divided into multiple sectors, and each sector can be divided into multiple cells. A cell can only belong to one TA, different cells in a base station can belong to different TAs, and the cells contained in a TA can belong to different base stations. Figure 2 In the example, each hexagon represents a TA, multiple TAs filled with dot patterns form a tracking area list, and multiple TAs filled with right-slash patterns form another tracking area list. Currently, VMR devices are proposed based on vehicle-mounted scenarios. VMR devices are usually deployed on moving vehicles. A VMR device consists of a base station and a UE. The UE can be called a VMR-UE, and the base station can be called a VMR-base station. Since the vehicle moves, the VMR-base station and the VMR-UE also have mobility. Among them, the VMR-UE has the functions of an ordinary UE and can access the core network through NR. Usually, the N2 backhaul link between the fixed ground base station on the ground and the core network can be realized through optical fiber. The N2 backhaul link between the mobile VMR-base station and the core network can be carried on the PDU session between the VMR-UE and the core network to realize wireless backhaul, so that the VMR-base station can provide wireless access for other UEs near the vehicle. Among them, the VMR device can also be called a Wireless Access and Backhauling (WAB) device, the UE constituting the WAB can be called a WAB-UE, and the base station constituting the WAB can be called a WAB-base station.

[0139] The following explanation is given by taking the VMR-base station in the VMR device as a VMR-gNB as an example.

[0140] Figure 3This is a schematic diagram of the basic architecture of VMR. VMR-UE accesses the core network through a host base station (such as donor-gNB) on the ground outside the vehicle, and establishes a PDU session between VMR-UE and UPF. The N2 message transmission between VMR-gNB and AMF is realized through the PDU session between VMR-UE and UPF. For example, when VMR-gNB needs to send an N2 message to AMF, VMR-gNB forwards the N2 message to VMR-UE through the internal interface between VMR-gNB and VMR-UE. VMR-UE uses the N2 message as the payload of the data packet and passes it to the corresponding UPF through the established PDU session. UPF then forwards the data packet to AMF to complete the forwarding of the N2 message. Among them, the host base station is also called a macro base station.

[0141] Figure 4 The schematic diagram of forwarding N2 message between VMR-gNB and AMF through PDU session is as follows:

[0142] Step 401, the VMR-gNB sends an N2 request message to the VMR-UE. Accordingly, the VMR-UE receives the N2 request message.

[0143] The source IP address of the N2 request message is the IP address of the VMR-UE, and the destination address is the address of the AMF.

[0144] The N2 request message may be a next generation setup request (NGsetup request) message. The VMR-gNBID is carried in the NG setup request message.

[0145] Step 402: VMR-UE matches the correct PDU session for the N2 request message.

[0146] For example, the VMR-UE matches the correct PDU session according to the corresponding source IP address and / or destination address (ie, the address of the AMF) of the N2 request message.

[0147] Step 403: VMR-UE sends uplink data to UPF via PDU session. Correspondingly, UPF receives the uplink data.

[0148] The payload of the uplink data includes an N2 request message, the source IP address in the uplink data is the IP address of the VMR-UE, and the destination address in the uplink data is the address of the AMF. The AMF is the AMF accessed by the VMR-gNB through the wireless backhaul link.

[0149] Step 404: UPF sends an N2 request message to AMF according to the destination address in the uplink data. Correspondingly, AMF receives the N2 request message.

[0150] Step 405: AMF sends an N2 response message to UPF. Accordingly, UPF receives the N2 response message.

[0151] For example, after AMF processes the N2 request message from VMR-gNB, it constructs an N2 response message, the destination address of which is the IP address of VMR-UE and the source address is the address of AMF. Then AMF sends the N2 response message to UPF.

[0152] Step 406: UPF sends downlink data to VMR-UE via PDU session. Correspondingly, VMR-UE receives the downlink data.

[0153] The payload of the downlink data includes an N2 response message, the source IP address in the downlink data is the address of the AMF, and the destination address in the downlink data is the IP address of the VMR-UE.

[0154] Step 407: VMR-UE sends an N2 response message to VMR-gNB. Accordingly, VMR-gNB receives the N2 response message.

[0155] The VMR-UE receives the downlink data packet, decapsulates it and obtains the N2 response message. If it finds that the N2 response message is not sent to itself, it forwards the N2 response message to the VMR-gNB.

[0156] At this point, the forwarding process of uplink and downlink N2 messages (i.e., N2 request message and N2 response message) has been completed between VMR-gNB and AMF.

[0157] According to the above introduction, the PDU session established by VMR-UE can be used to carry the N2 message between VMR-gNB and AMF, thereby realizing the N2 wireless backhaul link. However, there are still the following problems to be solved:

[0158] First, how to determine which AMF the VMR-gNB accesses when establishing the N2 wireless backhaul link through the PDU session?

[0159] Second, how to obtain the identification information of the AMF that the VMR-gNB accesses by establishing the N2 wireless backhaul link through the PDU session?

[0160] Third, when the VMR moves, how to trigger the AMF to change?

[0161] To solve the above problems, the embodiments of the present application provide corresponding solutions.

[0162] FIG5(a) is a flow chart of a communication method provided in an embodiment of the present application. The method is performed by a base station (or a module of a base station), a UE (or a module of a UE), and a first AMF (or a module of a first AMF). Optionally, the method also includes other steps performed by an SMF (or a module of an SMF). The base station here refers to a VMR-base station (e.g. Figure 3 The UE here refers to the VMR-UE in the VMR device (for example Figure 3 The first AMF here refers to the AMF registered by the VMR-UE (which can be called VMR-AMF). Alternatively, the base station in Figure 5(a) refers to the WAB-base station in the WAB device, and the UE in Figure 5(a) refers to the WAB-UE in the WAB device. The WAB-UE and the WAB-base station form a wireless access backhaul device, and the first AMF refers to the AMF registered by the WAB-UE in the WAB device (which can be called WAB-AMF).

[0163] In the following description, a UE and a base station are used as an example to illustrate a VMR device. The method includes the following steps:

[0164] Step 501a: The first AMF sends a first message to the UE. Correspondingly, the UE receives the first message.

[0165] The first message includes identification information of the second AMF. The second AMF is the AMF accessed by the base station through the wireless backhaul link.

[0166] Among them, the identification information of the second AMF may be the address of the second AMF, or the domain name corresponding to the second AMF (such as a fully qualified domain name (FQDN), or the globally unique AMF ID (GUAMI) of the second AMF). It should be noted that the specific examples of identification information of other AMFs (such as the third AMF) that appear later in this application are similar. The identification information of AMF is uniformly described here and will not be repeated later.

[0167] The second AMF can be the same AMF as the first AMF, or a different AMF.

[0168] Optionally, if the first AMF and the second AMF are different AMFs, the first message may also include the service area of ​​the second AMF, and the UE may send the service area of ​​the second AMF to the base station. Thus, the UE or the base station may determine whether it is necessary to update the AMF accessed by the base station through the wireless backhaul link based on the service area of ​​the second AMF. The service area may be, for example, TAI or longitude and latitude information.

[0169] Optionally, if the first AMF and the second AMF are the same AMF, the first AMF can obtain the identification information of the second AMF locally.

[0170] Optionally, if the first AMF and the second AMF are different AMFs, the first AMF may send a query request to a network element such as NRF or UDM, the query request including the location information of the UE, and the query request is used to query the identification information of the AMF that can be accessed through the wireless backhaul link, so that the NRF or UDM sends a query response to the first AMF based on the query request, and the query response includes the identification information of the second AMF. Among them, the identification information of the second AMF obtained by the NRF or UDM may be related to the location information of the UE, or it may not be related to it, which is not limited in this application.

[0171] Step 502a, the UE sends identification information of the second AMF to the base station. Correspondingly, the base station receives the identification information of the second AMF.

[0172] After the base station receives the identification information of the second AMF, it can access the second AMF through the PDU session. The specific process can be referred to Figure 4 Description of embodiments.

[0173] In the above scheme, the VMR base station can receive the identification information of the second AMF, and the VMR base station accesses the second AMF through the wireless backhaul link, thereby allocating a suitable AMF for the VMR base station to access the wireless backhaul link.

[0174] The first message may be a NAS response message, or a session establishment acceptance message in the PDU session establishment process, which will be described in detail below.

[0175] In scenario 1, the first message is a NAS response message.

[0176] For scenario 1, before step 501a, the UE sends a NAS request message to the first AMF, and the above-mentioned first message is a NAS response message.

[0177] Exemplarily, the NAS request message may be a registration request message or a service request message, which is not limited in this application. The registration request message is used to request registration to the network, and the service request message is used to request to establish a link to the network. Accordingly, the NAS response message may be a registration acceptance message or a service response message.

[0178] Optionally, the NAS request message includes first indication information, where the first indication information is used to indicate at least one of the following:

[0179] 1) UE type, where the UE type indicates that the UE is a vehicle-mounted relay UE co-located with a base station;

[0180] 2) UE capability, where the UE capability is the ability of the UE to establish a wireless backhaul link using a PDU session.

[0181] 3) Request identification information of the AMF accessed via the wireless backhaul link.

[0182] The first AMF obtains the identification information of the second AMF according to the first indication information and sends the identification information of the second AMF to the UE. That is, the first indication information triggers the first AMF to obtain the identification information of the second AMF.

[0183] As another implementation method, the above-mentioned first indication information can also be stored in the UDM, for example, the UDM stores the contract information of the UE, and the contract information includes the first indication information. Thus, the first AMF can obtain the first indication information from the UDM, and then obtain the identification information of the second AMF according to the first indication information and send the identification information of the second AMF to the UE.

[0184] For the first scenario, the UE can also send a session establishment request message and receive a session establishment acceptance message, which includes the UE's address information, which is allocated by the SMF. The UE then sends the UE's address information to the base station. After the base station receives the UE's address information, when it needs to communicate with the AMF through the N2 backhaul link, it can request the UE to transmit the N2 message through the user plane based on the UE's address information. For details, please refer to Figure 4 Description of embodiments.

[0185] Scenario 2: The first message is a session establishment acceptance message.

[0186] For the second scenario, before step 501a, the UE sends a session establishment request message to the first AMF, and the session establishment request message includes the identification information of the PDU session, then the above-mentioned first message is a session establishment acceptance message. Exemplarily, after receiving the session establishment request message, the first AMF sends a session context establishment request message to the SMF, and the session context establishment request message includes the identification information of the second AMF, and then the SMF sends a session context establishment response message to the first AMF, and the session context establishment response message includes a session establishment acceptance message, and the session establishment acceptance message includes the identification information of the second AMF, and then the first AMF sends a session establishment acceptance message to the UE, so that the UE can obtain the identification information of the second AMF from the session establishment acceptance message.

[0187] Optionally, the session establishment request message includes second indication information, and the second indication information is used to indicate that the PDU session is used to establish a wireless backhaul link. The first AMF obtains the identification information of the second AMF based on the second indication information and sends the identification information of the second AMF to the UE. That is, the second indication information triggers the first AMF to obtain the identification information of the second AMF.

[0188] For the second scenario, the session establishment acceptance message may also include the address information of the UE, which is allocated by the SMF. The UE then sends the address information of the UE to the base station. After the base station receives the address information of the UE, when it needs to communicate with the AMF through the N2 backhaul link, it can request the UE to transmit the N2 message through the user plane based on the address information of the UE. For details, please refer to Figure 4 Description of the embodiment. Alternatively, the UE may not send the UE address information to the base station, and when the UE subsequently receives an N2 message from the base station, the N2 message may be encapsulated in uplink data, and the UE actively adds the UE address information as the source IP address in the uplink data.

[0189] As an implementation method, for the above-mentioned scenario 1 or scenario 2, after step 502a, if the vehicle moves, and the UE and the base station on the vehicle move accordingly, the base station may access a new AMF through the wireless backhaul link. For example, the UE receives a second message, and the second message includes identification information of a third AMF, and then the UE sends identification information of the third AMF to the base station, and the third AMF is the AMF accessed by the base station through the wireless backhaul link, that is, the AMF accessed by the base station through the wireless backhaul link is updated from the second AMF to the third AMF, or the third AMF is the AMF newly registered by the UE, that is, the AMF registered by the UE is updated from the first AMF to the third AMF.

[0190] In one implementation method, the second message is a configuration update message from a third AMF (for example, a configuration update response message), that is, the third AMF sends a configuration update message to the UE, and the configuration update message includes identification information of the third AMF.

[0191] In another implementation method, the second message is a session modification message from the SMF, that is, the SMF sends a session modification message to the UE, and the session modification message includes identification information of the third AMF.

[0192] Optionally, the second message also includes the service area of ​​the third AMF and / or the new IP address of the UE.

[0193] As an implementation method, the base station may determine that the base station has moved out of the service area of ​​the second AMF, and then send a configuration update request message to the UE, the configuration update request message includes the current location information of the base station or the UE, and the configuration update request message is used to request the discovery of a new AMF. The UE sends the configuration update request message to the UPF through the PDU session, and the UPF forwards the configuration update request message to the second AMF. Then the second AMF obtains the identification information of the third AMF and the service area of ​​the third AMF from the NRF or UDM according to the current location information of the base station or the UE, and sends a configuration update response message (i.e., the second message) to the UPF, the configuration update response message includes the identification information of the third AMF and the service area of ​​the third AMF, and the UPF sends a configuration update response message to the UE through the PDU session, and then the UE sends a configuration update response message to the base station. Thus, the base station obtains the identification information of the third AMF and the service area of ​​the third AMF.

[0194] As another implementation method, the first AMF may determine that the UE or the base station has moved out of the service area of ​​the second AMF, and then the first AMF or the third AMF sends a configuration update message to the UE, the configuration update message includes the identification information of the third AMF, and then the UE sends a configuration update message to the base station. Thus, the base station obtains the identification information of the third AMF.

[0195] As another implementation method, the first AMF may determine that the UE or base station has moved out of the service area of ​​the second AMF, and then the SMF sends a session modification message to the UE, the session modification message includes the identification information of the third AMF, and then the UE sends a configuration update message to the base station. Thus, the base station obtains the identification information of the third AMF.

[0196] Figure 5(b) is a flow chart of a communication method provided in an embodiment of the present application. The method is executed by a vehicle-mounted relay device (or a module of a vehicle-mounted relay device) and a first AMF (or a module of the first AMF). The first AMF here refers to the AMF registered by the vehicle-mounted relay device (which can be called VMR-AMF). The vehicle-mounted relay device has both the functions of a UE and the functions of a base station. Among them, the vehicle-mounted relay device in Figure 5(b) can also be replaced by a WAB device that has both the functions of a UE and the functions of a base station. The method includes the following steps:

[0197] Step 501b: The first AMF sends a first message to the vehicle-mounted relay device. Correspondingly, the vehicle-mounted relay device receives the first message.

[0198] The first message includes identification information of the second AMF. The second AMF is the AMF accessed by the vehicle-mounted relay device through the wireless backhaul link. It can also be understood that the second AMF is the AMF accessed by the base station function in the vehicle-mounted relay through the wireless backhaul link.

[0199] The second AMF can be the same AMF as the first AMF, or a different AMF.

[0200] Optionally, if the first AMF and the second AMF are different AMFs, the first message may also include the service area of ​​the second AMF, so that the vehicle-mounted relay device can determine whether it is necessary to update the AMF accessed by the vehicle-mounted relay device through the wireless backhaul link according to the service area of ​​the second AMF. The service area may be, for example, TAI or longitude and latitude information.

[0201] Optionally, if the first AMF and the second AMF are the same AMF, the first AMF can obtain the identification information of the second AMF locally.

[0202] Optionally, if the first AMF and the second AMF are different AMFs, the first AMF may send a query request to a network element such as NRF or UDM, the query request including the location information of the vehicle-mounted relay device, and the query request is used to query the identification information of the AMF that can be accessed through the wireless backhaul link, so that the NRF or UDM sends a query response to the first AMF based on the query request, and the query response includes the identification information of the second AMF. Among them, the identification information of the second AMF obtained by the NRF or UDM may be related to the location information of the vehicle-mounted relay device, or it may not be related to the location information of the vehicle-mounted relay device, which is not limited in this application.

[0203] Step 502b, the vehicle relay device accesses the second AMF through the PDU session.

[0204] In the above scheme, the vehicle-mounted relay device can receive the identification information of the second AMF, and the vehicle-mounted relay device accesses the second AMF through the wireless backhaul link, thereby allocating a suitable AMF for accessing the wireless backhaul link to the vehicle-mounted relay device.

[0205] After the vehicle-mounted relay device receives the identification information of the second AMF, it can find the second AMF. When it needs to communicate with the second AMF through the N2 backhaul link later, it can follow Figure 4 process to execute.

[0206] The first message in the embodiment of FIG5(b) may be a NAS response message in the registration process, or a session establishment acceptance message in the PDU session establishment process, as described in detail below.

[0207] Case A, the first message is a NAS response message.

[0208] For situation A, before step 501b, the vehicle relay device sends a NAS request message to the first AMF, and the above-mentioned first message is a NAS response message.

[0209] Exemplarily, the NAS request message may be a registration request message or a service request message, which is not limited in this application. The registration request message is used to request registration to the network, and the service request message is used to request to establish a link to the network. Accordingly, the NAS response message may be a registration acceptance message or a service response message.

[0210] Optionally, the NAS request message includes first indication information, where the first indication information is used to indicate at least one of the following:

[0211] 1) The type of the vehicle-mounted relay device, which is a vehicle-mounted relay device;

[0212] 2) The capability of the on-board relay device, which is the ability to establish a wireless backhaul link using a PDU session.

[0213] 3) Request identification information of the AMF accessed via the wireless backhaul link.

[0214] The first AMF obtains the identification information of the second AMF according to the first indication information and sends the identification information of the second AMF to the vehicle-mounted relay device. That is, the first indication information triggers the first AMF to obtain the identification information of the second AMF.

[0215] As another implementation method, the above-mentioned first indication information can also be stored in the UDM, for example, the UDM stores the contract information of the vehicle-mounted relay device, and the contract information includes the first indication information. Thus, the first AMF can obtain the first indication information from the UDM, and then obtain the identification information of the second AMF according to the first indication information and send the identification information of the second AMF to the vehicle-mounted relay device.

[0216] For this scenario A, the vehicle relay device can also send a session establishment request message and receive a session establishment acceptance message, which includes the address information of the vehicle relay device, and the address information of the vehicle relay device is allocated by the SMF. After the vehicle relay device receives the address information of the vehicle relay device, when it needs to communicate with the second AMF through the N2 backhaul link, it can transmit the N2 message through the user plane based on the address information of the vehicle relay device. For details, please refer to Figure 4 Description of embodiments.

[0217] In case B, the first message is a session establishment accept message.

[0218] For this scenario B, before step 501b, the vehicle-mounted relay device sends a session establishment request message to the first AMF, and the session establishment request message includes the identification information of the PDU session, then the above-mentioned first message is a session establishment acceptance message. Exemplarily, after receiving the session establishment request message, the first AMF sends a session context establishment request message to the SMF, and the session context establishment request message includes the identification information of the second AMF, and then the SMF sends a session context establishment response message to the first AMF, and the session context establishment response message includes a session establishment acceptance message, and the session establishment acceptance message includes the identification information of the second AMF, and then the first AMF sends a session establishment acceptance message to the vehicle-mounted relay device, so that the vehicle-mounted relay device can obtain the identification information of the second AMF from the session establishment acceptance message.

[0219] Optionally, the session establishment request message includes a second indication information, and the second indication information is used to indicate that the PDU session is used to establish a wireless backhaul link. The first AMF obtains the identification information of the second AMF based on the second indication information and sends the identification information of the second AMF to the vehicle-mounted relay device. That is, the second indication information triggers the first AMF to obtain the identification information of the second AMF.

[0220] For the situation B, optionally, the session establishment acceptance message also includes the address information of the vehicle-mounted relay device, and the address information of the vehicle-mounted relay device is allocated by the SMF. Among them, since the vehicle-mounted relay device also has the function of UE, the process of SMF allocating an address to the vehicle-mounted relay device can be the process of SMF allocating an address to the UE in the session establishment process. This process is a prior art and will not be described again. As an implementation method, for the above situation A or situation B, after step 502b, if the vehicle moves, and then the vehicle-mounted relay device on the vehicle moves accordingly, the vehicle-mounted relay device may access the new AMF through the wireless backhaul link. For example, the vehicle-mounted relay device receives a second message, and the second message includes the identification information of the third AMF. The third AMF is the AMF accessed by the vehicle-mounted relay device through the wireless backhaul link, that is, the AMF accessed by the vehicle-mounted relay device through the wireless backhaul link is updated from the second AMF to the third AMF, or the third AMF is the AMF newly registered by the vehicle-mounted relay device, that is, the AMF registered by the vehicle-mounted relay device is updated from the first AMF to the third AMF.

[0221] In one implementation method, the second message is a configuration update message from a third AMF, that is, the third AMF sends a configuration update message to the vehicle-mounted relay device, and the configuration update message includes identification information of the third AMF.

[0222] In another implementation method, the second message is a session modification message from the SMF, that is, the SMF sends a session modification message to the vehicle-mounted relay device, and the session modification message includes identification information of the third AMF.

[0223] Optionally, the above second message also includes the service area of ​​the third AMF and / or the new IP address of the vehicle-mounted relay device.

[0224] As an implementation method, the vehicle-mounted relay device may determine that the vehicle-mounted relay device has moved out of the service area of ​​the second AMF, and then send a configuration update request message to the UPF through the PDU session. The configuration update request message includes the current location information of the vehicle-mounted relay device. The configuration update request message is used to request the discovery of a new AMF. The UPF forwards the configuration update request message to the second AMF. Then the second AMF obtains the identification information of the third AMF and the service area of ​​the third AMF from the NRF or UDM based on the current location information of the vehicle-mounted relay device, and sends a configuration update response message (i.e., the second message) to the UPF. The configuration update response message includes the identification information of the third AMF and the service area of ​​the third AMF. The UPF sends a configuration update response message to the vehicle-mounted relay device through the PDU session, so that the vehicle-mounted relay device obtains the identification information of the third AMF and the service area of ​​the third AMF.

[0225] As another implementation method, the first AMF may determine that the vehicle-mounted relay device has moved out of the service area of ​​the second AMF, and then the first AMF or the third AMF sends a configuration update message to the vehicle-mounted relay device, and the configuration update message includes the identification information of the third AMF, so that the vehicle-mounted relay device obtains the identification information of the third AMF.

[0226] As another implementation method, the first AMF may determine that the vehicle-mounted relay device has moved out of the service area of ​​the second AMF, and then the SMF sends a session modification message to the vehicle-mounted relay device, and the session modification message includes the identification information of the third AMF, so that the vehicle-mounted relay device obtains the identification information of the third AMF.

[0227] under Figures 6 to 9 , Figure 11 to Figure 12 A specific embodiment is combined with Figure 3 The above-mentioned embodiment of FIG5(a) is described in detail. Figures 6 to 8 In the embodiment of the present invention, the AMF registered by the VMR-UE is the same AMF as the AMF used for accessing the N2 wireless backhaul link. Fig. 9 , Fig.11 and Fig.12 In the embodiment, the AMF registered by the VMR-UE is a different AMF from the AMF used for N2 wireless backhaul link access.

[0228] Figure 6 A flow chart of a communication method provided in an embodiment of the present application. The method comprises the following steps:

[0229] Step 601: VMR-gNB sends a request message to VMR-UE. Correspondingly, VMR-UE receives the request message.

[0230] This request message is used to request the VMR-UE to discover the AMF that can be used as N2 wireless backhaul.

[0231] Step 602: VMR-UE sends a NAS request message to VMR-AMF-1. Correspondingly, VMR-AMF-1 receives the NAS request message.

[0232] For example, the NAS request message may be a registration request message or a service request message, which is not limited in this application.

[0233] The registration request message is used to request registration to the network, and the service request message is used to request establishment of a link to the network.

[0234] Optionally, the NAS request message includes indication information, where the indication information is used to indicate at least one of the following:

[0235] 1) The type of VMR-UE, for example, the UE is a VMR-UE co-located with a gNB or the UE is a vehicle-mounted relay device.

[0236] 2) The capability of the VMR-UE, for example, the UE has the capability to establish a wireless backhaul link using a PDU session.

[0237] 3) Request identification information of the AMF accessed via the wireless backhaul link.

[0238] Step 603, VMR-AMF-1 determines the identification information of VMR-AMF-1

[0239] That is, VMR-AMF-1 determines to use VMR-AMF-1 as the AMF for wireless link backhaul of VMR-gNB.

[0240] As an implementation method, VMR-AMF-1 may determine the type of VMR-UE according to the indication information in the NAS request message and / or the indication information in the subscription information from the UDM, and then trigger VMR-AMF-1 to determine the identification information of VMR-AMF-1 based on the type of VMR-UE. Optionally, after VMR-AMF-1 determines the type of VMR-UE, it may store the type of VMR-UE in the UE context.

[0241] As another implementation method, VMR-AMF-1 may determine the capability of the VMR-UE according to the indication information in the NAS request message and / or the indication information in the subscription information from the UDM, and then trigger VMR-AMF-1 to determine the identification information of VMR-AMF-1 based on the capability of the VMR-UE. Optionally, after VMR-AMF-1 determines the capability of the VMR-UE, it may store the capability of the VMR-UE in the UE context.

[0242] As another implementation method, VMR-AMF-1 can trigger VMR-AMF-1 to determine the identification information of VMR-AMF-1 based on the indication information in the NAS request message for requesting the identification information of the AMF accessed through the wireless backhaul link.

[0243] Step 604: VMR-AMF-1 sends a NAS response message to VMR-UE. Correspondingly, VMR-UE receives the NAS response message.

[0244] The NAS response message includes identification information of VMR-AMF-1.

[0245] The NAS response message may be a registration acceptance message or a service response message.

[0246] Step 605: The VMR-UE sends a response message to the VMR-gNB. Accordingly, the VMR-gNB receives the response message.

[0247] The response message includes identification information of VMR-AMF-1.

[0248] If the identification information of VMR-AMF-1 is a domain name corresponding to VMR-AMF-1 or a GUAMI of VMR-AMF-1, VMR-UE may query the address of VMR-AMF-1 corresponding to the domain name or GUAMI through a domain name system (DNS).

[0249] Step 606a, the VMR-gNB sends a connection establishment request message to the VMR-UE. Correspondingly, the VMR-UE receives the connection establishment request message.

[0250] The connection establishment request message is used to request the VMR-UE to initiate the establishment of an N2 wireless backhaul link.

[0251] Step 606b: VMR-UE sends a PDU session establishment request message to VMR-AMF-1. Correspondingly, VMR-AMF-1 receives the PDU session establishment request message.

[0252] The PDU session establishment request message includes a PDU session ID, and optionally also includes indication information, where the indication information is used to indicate that the PDU session is used to establish an N2 wireless backhaul link.

[0253] Step 607: VMR-AMF-1 selects an SMF to serve the PDU session.

[0254] Step 608: VMR-AMF-1 sends a PDU session context establishment request to SMF. Correspondingly, SMF receives the PDU session context establishment request.

[0255] Optionally, the PDU session context establishment request includes identification information of VMR-AMF-1.

[0256] Specifically, if the indication information is carried in step 606b, VMR-AMF-1 determines that the PDU session is used to establish the N2 wireless backhaul link based on the indication information carried in step 606b, so VMR-AMF-1 carries the identification information of VMR-AMF-1 in the PDU session context establishment request and sends it to SMF. Alternatively, VMR-AMF-1 can determine that the PDU session is used to establish the N2 wireless backhaul link based on the UE type and / or UE capabilities contained in the UE context, and carries the identification information of VMR-AMF-1 in the PDU session context establishment request and sends it to SMF (for example, when the indication information is not included in step 606b).

[0257] Exemplarily, the PDU session context establishment request may be a service operation Nsmf_PDUSession_CreateSMContext Request called by VMR-AMF-1.

[0258] SMF selects the appropriate UPF based on the address of VMR-AMF-1. At the same time, SMF also allocates an IP address to VMR-UE.

[0259] Among them, if the identification information of VMR-AMF-1 is the address of VMR-AMF-1, then SMF can directly select a suitable UPF according to the address information. If the identification information of VMR-AMF-1 is the domain name corresponding to VMR-AMF-1 or the GUAMI of VMR-AMF-1, SMF can query the address of VMR-AMF-1 corresponding to the domain name or GUAMI through NRF, and then select a suitable UPF according to the address information.

[0260] Step 609a, SMF sends an N4 session establishment request to UPF. Correspondingly, UPF receives the N4 session establishment request.

[0261] The N4 session establishment request includes a packet detection rule (PDR) and a forwarding action rule (FAR).

[0262] UPF identifies data packets belonging to sessions or service data flows based on the PDR sent by SMF, and processes service messages based on the FAR provided by SMF.

[0263] Step 609b, UPF sends an N4 session establishment response to SMF. Correspondingly, SMF receives the N4 session establishment response.

[0264] Step 610: SMF sends a PDU session context establishment response to VMR-AMF-1. Correspondingly, VMR-AMF-1 receives the PDU session context establishment response.

[0265] The PDU session context establishment response includes a PDU session establishment acceptance message, and the PDU session establishment acceptance message includes the IP address of the VMR-UE.

[0266] Exemplarily, the PDU session context establishment response may be a service operation Nsmf_PDUSession_CreateSMContext Response called by the SMF.

[0267] Step 611, VMR-AMF-1 sends a PDU session establishment accept message to VMR-UE. Correspondingly, VMR-UE receives the PDU session establishment accept message.

[0268] In step 612, the VMR-UE sends a connection establishment response message to the VMR-gNB. Accordingly, the VMR-gNB receives the connection establishment response message.

[0269] The connection establishment response message includes the IP address of the VMR-UE.

[0270] After step 612, the VMR-gNB and VMR-AMF-1 can forward the N2 message through the PDU session. For details, please refer to Figure 4 Description of embodiments.

[0271] Step 613: The VMR-UE moves, and VMR-AMF-1 determines that the VMR-UE has moved out of the service area of ​​VMR-AMF-1, and switches to VMR-AMF-2 to provide service for the VMR-UE.

[0272] The service area can be represented by a TA list.

[0273] Step 614a, VMR-AMF-2 sends a configuration update message to VMR-UE. Correspondingly, VMR-UE receives the configuration update message.

[0274] The configuration update message includes identification information of VMR-AMF-2.

[0275] The configuration update message is also called a UE configuration update message.

[0276] Specifically, VMR-AMF-2 obtains the context information of the UE from VMR-AMF-1, which includes the type of the VMR-UE and / or the capabilities of the VMR-UE. VMR-AMF-2 determines to send a configuration update message to the VMR-UE according to the type of the VMR-UE and / or the capabilities of the VMR-UE.

[0277] In step 614b, the VMR-UE sends the identification information of VMR-AMF-2 to the VMR-gNB. Accordingly, the VMR-gNB receives the identification information of VMR-AMF-2.

[0278] The VMR-gNB learns that the AMF accessed through the N2 wireless backhaul link has been updated from VMR-AMF-1 to VMR-AMF-2.

[0279] Step 615a, the VMR-gNB sends a connection establishment request message to the VMR-UE. Correspondingly, the VMR-UE receives the connection establishment request message.

[0280] The connection establishment request message is used to request the VMR-UE to initiate an N2 wireless backhaul link, thereby triggering the VMR-UE to establish a PDU session for accessing the VMR-AMF-2.

[0281] Step 615b, VMR-UE sends a PDU session establishment request message to VMR-AMF-2. Correspondingly, VMR-AMF-2 receives the PDU session establishment request message.

[0282] The PDU session establishment request message includes a PDU session ID, and optionally also includes indication information, where the indication information is used to indicate that the PDU session is used to establish an N2 wireless backhaul link.

[0283] Step 616, similar to the above steps 607 to 611, establishes a PDU session for accessing VMR-AMF-2. At the same time, SMF allocates a new IP address for VMR-UE.

[0284] In step 617, the VMR-UE sends a connection establishment response message to the VMR-gNB. Accordingly, the VMR-gNB receives the connection establishment response message.

[0285] The connection establishment response message includes the new IP address of the VMR-UE.

[0286] In the above scheme, the AMF accessed by the VMR-gNB through the N2 wireless backhaul link is the VMR-AMF currently accessed by the VMR-UE, and during the movement of the VMR, the N2 wireless backhaul link can be updated based on the VMR-AMF relocation process.

[0287] Figure 7 A flow chart of a communication method provided in an embodiment of the present application. The method comprises the following steps:

[0288] Step 701 to step 712, same Figure 6 Steps 601 to 612 of the embodiment.

[0289] Step 713: The VMR-UE moves, and VMR-AMF-1 determines that the VMR-UE has moved out of the service area of ​​VMR-AMF-1, and switches to VMR-AMF-2 to provide service for the VMR-UE.

[0290] The service area can be represented by a TA list.

[0291] Step 714: VMR-AMF-2 sends a PDU session modification request message to SMF. Correspondingly, SMF receives the PDU session modification request message.

[0292] The PDU session modification request message includes the PDU session ID and identification information of the VMR-AMF-2.

[0293] Specifically, VMR-AMF-2 obtains the UE context information from VMR-AMF-1, which includes the type of VMR-UE and / or the capabilities of VMR-UE, and the PDU session ID. VMR-AMF-2 determines to send a PDU session modification request message to SMF according to the type of VMR-UE and / or the capabilities of VMR-UE.

[0294] Step 715: SMF determines whether it is necessary to trigger updating of the PDU session anchor (PSA) based on the identification information of VMR-AMF-2.

[0295] If the SMF determines based on the identification information of VMR-AMF-2 that the PSA access path based on VMR-AMF-2 for the current session is not optimized, for example, the latency requirement of the wireless backhaul link cannot be met, it is necessary to trigger the update of the PSA. For example, the process of updating the PSA can be the following:

[0296] 1) If the session and service continuity mode (SSC) corresponding to the current PDU session is mode 3, SMF can initiate a session modification process, which can trigger the VMR-UE to initiate a new session establishment. That is, the VMR-UE subsequently accesses VMR-AMF-2 through the anchor point of the new session.

[0297] 2) SMF selects a new PSA for the current PDU session and inserts an uplink classifier UPF (ULCL UPF) or a branching point (BP) to optimize the user plane path for accessing VMR-AMF-2. That is, the subsequent VMR-UE accesses VMR-AMF-2 through the new PSA.

[0298] Among them, if the identification information of VMR-AMF-2 is the address of VMR-AMF-2, then SMF can directly select a suitable PSA according to the address information. If the identification information of VMR-AMF-2 is the domain name corresponding to VMR-AMF-2 or the GUAMI of VMR-AMF-2, SMF can query the address of VMR-AMF-2 corresponding to the domain name or GUAMI through NRF, and then select a suitable PSA according to the address information.

[0299] Step 716: SMF sends a PDU session modification message to the VMR-UE. Correspondingly, the VMR-UE receives the PDU session modification message.

[0300] The PDU session modification message includes the identification information of VMR-AMF-2 and, optionally, the new IP address assigned by SMF to VMR-UE. Step 717: VMR-UE sends a connection modification message to VMR-gNB. Accordingly, VMR-gNB receives the connection modification message.

[0301] The connection modification message is used to modify the N2 wireless backhaul link.

[0302] The connection modification message includes the identification information of VMR-AMF-2, and optionally, also includes a new IP address allocated by SMF to VMR-UE.

[0303] In the above scheme, the AMF accessed by the VMR-gNB through the N2 wireless backhaul link is the VMR-AMF currently accessed by the VMR-UE, and during the movement of the VMR, the N2 wireless backhaul link can be updated based on the VMR-AMF relocation process.

[0304] Figure 8 A flow chart of a communication method provided in an embodiment of the present application. The method comprises the following steps:

[0305] Step 801: VMR-UE sends a NAS request message to VMR-AMF-1. Correspondingly, VMR-AMF-1 receives the NAS request message.

[0306] For example, the NAS request message may be a registration request message or a service request message, which is not limited in this application.

[0307] The registration request message is used to request registration to the network, and the service request message is used to request establishment of a link to the network.

[0308] Optionally, the NAS request message includes indication information, where the indication information is used to indicate at least one of the following:

[0309] 1) The type of VMR-UE, for example, the UE is a VMR-UE co-located with a gNB or the UE is a vehicle-mounted relay device.

[0310] 2) The capability of the VMR-UE, for example, the UE has the capability to establish a wireless backhaul link using a PDU session.

[0311] 3) Request identification information of the AMF accessed via the wireless backhaul link.

[0312] Step 802: VMR-AMF-1 determines the type of VMR-UE and / or the capability of the VMR-UE.

[0313] This step 802 is an optional step.

[0314] VMR-AMF-1 determines the type of VMR-UE and / or the capability of VMR-UE according to the indication information in the NAS request message and / or the indication information in the subscription information. The subscription information may be stored in the UDM, and VMR-AMF-1 may obtain the subscription information of VMR-UE from the UDM.

[0315] The VMR-AMF-1 may store the type of the VMR-UE and / or the capabilities of the VMR-UE in the UE context.

[0316] Step 803: VMR-AMF-1 sends a NAS response message to VMR-UE. Correspondingly, VMR-UE receives the NAS response message.

[0317] The NAS response message may be a registration acceptance message or a service response message.

[0318] Step 804: The VMR-gNB sends a connection establishment request message to the VMR-UE. Correspondingly, the VMR-UE receives the connection establishment request message.

[0319] The connection establishment request message is used to request the VMR-UE to initiate an N2 wireless backhaul link.

[0320] Step 805: VMR-UE sends a PDU session establishment request message to VMR-AMF-1. Correspondingly, VMR-AMF-1 receives the PDU session establishment request message.

[0321] The PDU session establishment request message includes a PDU session ID, and optionally also includes indication information, where the indication information is used to indicate that the PDU session is used to establish an N2 wireless backhaul link.

[0322] Step 806: VMR-AMF-1 selects an SMF to serve the PDU session.

[0323] Step 807: VMR-AMF-1 sends a PDU session context establishment request to SMF. Correspondingly, SMF receives the PDU session context establishment request.

[0324] The PDU session context establishment request includes identification information of VMR-AMF-1.

[0325] For example, if the indication information is carried in step 805, VMR-AMF-1 determines that the PDU session is used to establish the N2 wireless backhaul link based on the indication information carried in step 805, so VMR-AMF-1 carries the identification information of VMR-AMF-1 in the PDU session context establishment request and sends it to SMF. Alternatively, VMR-AMF-1 can determine that the PDU session is used to establish the N2 wireless backhaul link based on the type of VMR-UE and / or the capabilities of VMR-UE contained in the UE context, and carries the identification information of VMR-AMF-1 in the PDU session context establishment request and sends it to SMF (for example, when the indication information is not included in step 805).

[0326] Exemplarily, the PDU session context establishment request may be a service operation Nsmf_PDUSession_CreateSMContext Request called by VMR-AMF-1.

[0327] SMF selects the appropriate UPF based on the identification information of VMR-AMF-1. At the same time, SMF also allocates an IP address to VMR-UE.

[0328] Step 808a, SMF sends an N4 session establishment request to UPF. Correspondingly, UPF receives the N4 session establishment request.

[0329] The N4 session establishment request includes a PDR and a FAR.

[0330] UPF identifies data packets belonging to sessions or service data flows based on the PDR sent by SMF, and processes service packets based on the FAR provided by SMF.

[0331] Step 808b, UPF sends an N4 session establishment response to SMF. Correspondingly, SMF receives the N4 session establishment response.

[0332] Step 809: SMF sends a PDU session context establishment response to VMR-AMF-1. Correspondingly, VMR-AMF-1 receives the PDU session context establishment response.

[0333] The PDU session context establishment response includes a PDU session establishment acceptance message, and the PDU session establishment acceptance message includes the IP address of the VMR-UE and the identification information of the VMR-SMF1.

[0334] Exemplarily, the PDU session context establishment response may be a service operation Nsmf_PDUSession_CreateSMContext Response called by the SMF.

[0335] Step 810: VMR-AMF-1 sends a PDU session establishment accept message to VMR-UE. Correspondingly, VMR-UE receives the PDU session establishment accept message.

[0336] Step 811: The VMR-UE sends a connection establishment response message to the VMR-gNB. Correspondingly, the VMR-gNB receives the connection establishment response message.

[0337] The connection establishment response message includes the IP address of the VMR-UE and the identification information of the VMR-SMF1.

[0338] After step 811, the VMR-gNB and VMR-AMF-1 can forward the N2 message through the PDU session. For details, please refer to Figure 4 Description of embodiments.

[0339] Step 812: The VMR-UE moves, and VMR-AMF-1 determines that the VMR-UE has moved out of the service area of ​​VMR-AMF-1, and switches to VMR-AMF-2 to provide service for the VMR-UE.

[0340] The service area can be represented by a TA list.

[0341] Specifically, VMR-AMF-2 obtains the context information of the UE from VMR-AMF-1, which includes the type of the VMR-UE and / or the capability of the VMR-UE.

[0342] Step 813, VMR-AMF-2 sends a PDU session modification request message to SMF. Correspondingly, SMF receives the PDU session modification request message.

[0343] The PDU session modification request message includes identification information of VMR-AMF-2.

[0344] Specifically, VMR-AMF-2 determines to send a PDU session modification request message to SMF according to the type of VMR-UE and / or the capability of VMR-UE contained in the context information of the UE.

[0345] Step 814: SMF determines whether it is necessary to trigger the update of PSA based on the identification information of VMR-AMF-2.

[0346] If the SMF determines based on the identification information of VMR-AMF-2 that the PSA access path based on VMR-AMF-2 for the current session is not optimized, for example, the latency requirement of the wireless backhaul link cannot be met, it is necessary to trigger the update of the PSA. For example, the process of updating the PSA can be the following:

[0347] 1) If the SSC corresponding to the current PDU session is mode 3, SMF can initiate a session modification process, which can trigger the VMR-UE to initiate a new session establishment. That is, the VMR-UE subsequently accesses VMR-AMF-2 through the anchor point of the new session.

[0348] 2) SMF selects a new PSA for the current PDU session and inserts ULCL UPF or BP to optimize the user plane path for accessing VMR-AMF-2. That is, the subsequent VMR-UE accesses VMR-AMF-2 through the new PSA.

[0349] Among them, if the identification information of VMR-AMF-2 is the address of VMR-AMF-2, then SMF can directly select a suitable PSA according to the address information. If the identification information of VMR-AMF-2 is the domain name corresponding to VMR-AMF-2 or the GUAMI of VMR-AMF-2, SMF can query the address of VMR-AMF-2 corresponding to the domain name or GUAMI through NRF, and then select a suitable PSA according to the address information.

[0350] Step 815: SMF sends a PDU session modification message to the VMR-UE. Correspondingly, the VMR-UE receives the PDU session modification message.

[0351] The PDU session modification message includes the identification information of VMR-AMF-2, and optionally, also includes a new IP address allocated by SMF to VMR-UE.

[0352] In step 816, the VMR-UE sends a connection modification message to the VMR-gNB. Accordingly, the VMR-gNB receives the connection modification message.

[0353] The connection modification message is used to modify the N2 wireless backhaul link.

[0354] The connection modification message includes the identification information of VMR-AMF-2, and optionally, also includes a new IP address allocated by SMF to VMR-UE.

[0355] In the above scheme, the AMF accessed by the VMR-gNB through the N2 wireless backhaul link is the VMR-AMF currently accessed by the VMR-UE, and during the movement of the VMR, the N2 wireless backhaul link can be updated based on the VMR-AMF relocation process.

[0356] Fig. 9 A flow chart of a communication method provided in an embodiment of the present application. The method comprises the following steps:

[0357] Step 901, the AMF supporting the N2 wireless backhaul link sends a network function (NF) registration request to the NRF. Accordingly, the NRF receives the NF registration request.

[0358] The NF registration request carries the identification information of the AMF, the service area of ​​the AMF, and the indication information. Among them, the service area of ​​the AMF can be represented by a TA list, and the indication information is used to indicate that the AMF can be accessed through the N2 wireless backhaul link. The AMF here includes at least AMF-1 and AMF-2.

[0359] Step 902: The VMR-gNB sends a request message to the VMR-UE. Accordingly, the VMR-UE receives the request message.

[0360] This request message is used to request the VMR-UE to discover the AMF that can be used as N2 wireless backhaul.

[0361] Step 903: VMR-UE sends a NAS request message to VMR-AMF. Correspondingly, VMR-AMF receives the NAS request message.

[0362] For example, the NAS request message may be a registration request message or a service request message, which is not limited in this application.

[0363] The registration request message is used to request registration with the network, and the service request message is used to request establishment of a link with the network.

[0364] Optionally, the NAS request message includes indication information, where the indication information is used to indicate at least one of the following:

[0365] 1) The type of VMR-UE, for example, the UE is a VMR-UE co-located with a gNB or the UE is a vehicle-mounted relay device.

[0366] 2) The capability of the VMR-UE, for example, the UE has the capability to establish a wireless backhaul link using a PDU session.

[0367] 3) Request identification information of the AMF accessed via the wireless backhaul link.

[0368] Step 904a, VMR-AMF sends a query request to NRF. Correspondingly, NRF receives the query request.

[0369] The query request carries the location information of the VMR-UE and the NF type, where the NF type is used to indicate the AMF accessed via the N2 wireless backhaul link. The query request is used to query the identification information of the AMF that can be accessed via the N2 wireless backhaul link.

[0370] As an implementation method, the VMR-AMF may determine the type of the VMR-UE based on the indication information in the NAS request message and / or the indication information in the subscription information from the UDM, and then trigger the VMR-AMF to send a query request to the NRF based on the type of the VMR-UE. Optionally, after the VMR-AMF determines the type of the VMR-UE, the type of the VMR-UE may be stored in the UE context.

[0371] As another implementation method, the VMR-AMF may determine the capabilities of the VMR-UE based on the indication information in the NAS request message and / or the indication information in the subscription information from the UDM, and then trigger the VMR-AMF to send a query request to the NRF based on the capabilities of the VMR-UE. Optionally, after the VMR-AMF determines the capabilities of the VMR-UE, the capabilities of the VMR-UE may be stored in the UE context.

[0372] As another implementation method, the VMR-AMF may trigger the VMR-AMF to send a query request to the NRF based on the indication information in the NAS request message for requesting the identification information of the AMF accessed via the wireless backhaul link.

[0373] Step 904b, the NRF sends a query response to the VMR-AMF. Accordingly, the VMR-AMF receives the query response.

[0374] The query response carries the identification information of AMF-1 and the service area of ​​AMF-1, and the service area may be a TA list. For example, the identification information of AMF-1 may be the address of AMF-1.

[0375] Step 905: The VMR-AMF sends a NAS response message to the VMR-UE. Correspondingly, the VMR-UE receives the NAS response message.

[0376] The NAS response message includes the identification information of AMF-1.

[0377] The NAS response message may be a registration acceptance message or a service response message.

[0378] Step 906: The VMR-UE sends a response message to the VMR-gNB. Accordingly, the VMR-gNB receives the response message.

[0379] The response message includes the identification information of AMF-1.

[0380] Among them, if the identification information of AMF-1 is the domain name corresponding to AMF-1 or the GUAMI of AMF-1, the VMR-UE can query the address of AMF-1 corresponding to the domain name or GUAMI through the DNS system.

[0381] Step 907a: The VMR-gNB sends a connection establishment request message to the VMR-UE. Accordingly, the VMR-UE receives the connection establishment request message.

[0382] The connection establishment request message is used to request the VMR-UE to initiate an N2 wireless backhaul link.

[0383] Step 907b: VMR-UE sends a PDU session establishment request message to VMR-AMF. Correspondingly, VMR-AMF receives the PDU session establishment request message.

[0384] The PDU session establishment request message includes a PDU session ID, and optionally also includes indication information, where the indication information is used to indicate that the PDU session is used to establish an N2 wireless backhaul link.

[0385] Step 908: VMR-AMF selects the SMF that serves the PDU session.

[0386] Step 909: VMR-AMF sends a PDU session context establishment request to SMF. Correspondingly, SMF receives the PDU session context establishment request.

[0387] The PDU session context establishment request includes the identification information of AMF-1, and the AMF-1 is the AMF used for the N2 wireless backhaul link queried by the VMR-AMF.

[0388] For example, if the indication information is carried in step 907b, VMR-AMF determines that the PDU session is used to establish the N2 wireless backhaul link based on the indication information carried in step 907b, so VMR-AMF carries the identification information of AMF-1 in the PDU session context establishment request and sends it to SMF. Alternatively, VMR-AMF can determine that the PDU session is used to establish the N2 wireless backhaul link based on the type of VMR-UE and / or the capabilities of VMR-UE contained in the UE context, and carries the identification information of AMF-1 in the PDU session context establishment request and sends it to SMF (for example, when the indication information is not included in step 907b).

[0389] Exemplarily, the PDU session context establishment request may be a service operation Nsmf_PDUSession_CreateSMContext Request called by the VMR-AMF.

[0390] SMF selects the appropriate UPF based on the identification information of AMF-1. At the same time, SMF also allocates an IP address to the VMR-UE.

[0391] Among them, if the identification information of VMR-AMF-1 is the address of VMR-AMF-1, then SMF can directly select a suitable UPF according to the address information. If the identification information of VMR-AMF-1 is the domain name corresponding to VMR-AMF-1 or the GUAMI of VMR-AMF-1, SMF can query the address of VMR-AMF-1 corresponding to the domain name or GUAMI through NRF, and then select a suitable UPF according to the address information.

[0392] Step 910a, SMF sends an N4 session establishment request to UPF. Correspondingly, UPF receives the N4 session establishment request.

[0393] The N4 session establishment request includes a PDR and a FAR.

[0394] UPF identifies data packets belonging to sessions or service data flows based on the PDR sent by SMF, and processes service messages based on the FAR provided by SMF.

[0395] Step 910b, UPF sends an N4 session establishment response to SMF. Correspondingly, SMF receives the N4 session establishment response.

[0396] Step 911, SMF sends a PDU session context establishment response to VMR-AMF. Correspondingly, VMR-AMF receives the PDU session context establishment response.

[0397] The PDU session context establishment response includes a PDU session establishment acceptance message, and the PDU session establishment acceptance message includes the IP address of the VMR-UE.

[0398] Exemplarily, the PDU session context establishment response may be a service operation Nsmf_PDUSession_CreateSMContext Response called by the SMF.

[0399] Step 912: VMR-AMF sends a PDU session establishment accept message to VMR-UE. Correspondingly, VMR-UE receives the PDU session establishment accept message.

[0400] In step 913, the VMR-UE sends a connection establishment response message to the VMR-gNB. Accordingly, the VMR-gNB receives the connection establishment response message.

[0401] The connection establishment response message includes the IP address of the VMR-UE.

[0402] After step 913, the VMR-gNB and AMF-1 can forward the N2 message through the PDU session. For details, please refer to Figure 4 Description of embodiments.

[0403] Step 914: The VMR-UE moves, and the VMR-AMF determines that the VMR-UE has moved out of the service area of ​​AMF-1, and determines that the N2 wireless backhaul link needs to perform an AMF update.

[0404] Since the VMR-UE is registered with VMR-AMF, VMR-AMF can monitor the real-time location of VMR-UE, and VMR-AMF obtains the service area of ​​AMF-1 in the above step 904b. Therefore, when the VMR-UE moves, VMR-AMF first obtains the latest location of VMR-UE and determines whether the latest location has moved out of the service area of ​​AMF-1. If it has moved out, it is determined that the N2 wireless backhaul link needs to perform AMF update.

[0405] refer to Fig.10 , which is a schematic diagram of VMR movement. When VMR moves, VMR-UE moves out of the service area of ​​AMF-1 and enters the service area of ​​AMF-2.

[0406] Step 915a, VMR-AMF sends a query request to NRF. Correspondingly, NRF receives the query request.

[0407] The query request carries the location information of the VMR-UE and the NF type, where the NF type is used to indicate the AMF accessed via the N2 wireless backhaul link. The query request is used to query the identification information of the AMF that can be accessed via the N2 wireless backhaul link.

[0408] Specifically, the VMR-AMF determines to send a query request to the NRF according to the type of VMR-UE and / or the capability of the VMR-UE contained in the context information of the UE.

[0409] Step 915b, NRF sends a query response to VMR-AMF. Correspondingly, VMR-AMF receives the query response.

[0410] The query response carries the identification information of AMF-2 and the service area of ​​the AMF-2, and the service area may be a TA list.

[0411] Step 916: VMR-AMF sends a configuration update message to VMR-UE. Correspondingly, VMR-UE receives the configuration update message.

[0412] The configuration update message includes the identification information of AMF-2.

[0413] The configuration update message is also called a UE configuration update message.

[0414] In step 917, the VMR-UE sends the identification information of AMF-2 to the VMR-gNB. Accordingly, the VMR-gNB receives the identification information of AMF-2.

[0415] The VMR-gNB learns that the AMF accessed through the N2 wireless backhaul link has been updated from AMF-1 to AMF-2.

[0416] Step 918a, the VMR-gNB sends a connection establishment request message to the VMR-UE. Correspondingly, the VMR-UE receives the connection establishment request message.

[0417] The connection establishment request message is used to request the VMR-UE to initiate an N2 wireless backhaul link, thereby triggering the VMR-UE to establish a PDU session for accessing AMF-2.

[0418] Step 918b: VMR-UE sends a PDU session establishment request message to VMR-AMF. Correspondingly, VMR-AMF receives the PDU session establishment request message.

[0419] The PDU session establishment request message includes a PDU session ID and indication information, where the indication information is used to indicate that the PDU session is used to establish an N2 wireless backhaul link.

[0420] Step 919, similar to the above steps 908 to 912, establishes a PDU session for accessing AMF-2. At the same time, SMF allocates a new IP address for VMR-UE.

[0421] In step 920, the VMR-UE sends a connection establishment response message to the VMR-gNB. Accordingly, the VMR-gNB receives the connection establishment response message.

[0422] The connection establishment response message includes the new IP address of the VMR-UE.

[0423] In the above scheme, the AMF accessed by VMR-gNB through the N2 wireless backhaul link is different from the VMR-AMF currently accessed by VMR-UE. The AMF supporting the access of N2 wireless backhaul link is selected according to the current location of VMR-UE, and the update of N2 wireless backhaul link can be realized during the movement of VMR.

[0424] Fig.11 A flow chart of a communication method provided in an embodiment of the present application. The method comprises the following steps:

[0425] Step 1100, the AMF supporting the N2 wireless backhaul link sends a NF registration request to the NRF. Accordingly, the NRF receives the NF registration request.

[0426] The NF registration request carries the identification information of the AMF, the service area of ​​the AMF, and indication information. The service area of ​​the AMF can be represented by a TA list, and the indication information is used to indicate that the AMF can be accessed through the N2 wireless backhaul link. For example, the identification information of the AMF can be the address of the AMF.

[0427] The AMF here includes at least AMF-1 and AMF-2.

[0428] Step 1101: VMR-UE sends a NAS request message to VMR-AMF. Correspondingly, VMR-AMF receives the NAS request message.

[0429] For example, the NAS request message may be a registration request message or a service request message, which is not limited in this application.

[0430] The registration request message is used to request registration with the network, and the service request message is used to request establishment of a link with the network.

[0431] Optionally, the NAS request message includes indication information, where the indication information is used to indicate at least one of the following:

[0432] 1) The type of VMR-UE, for example, the UE is a VMR-UE co-located with a gNB or the UE is a vehicle-mounted relay device.

[0433] 2) The capability of the VMR-UE, for example, the UE has the capability to establish a wireless backhaul link using a PDU session.

[0434] 3) Request identification information of the AMF accessed via the wireless backhaul link.

[0435] Step 1102: The VMR-AMF determines the type of the VMR-UE and / or the capability of the VMR-UE.

[0436] This step 1102 is an optional step.

[0437] The VMR-AMF determines the type of the VMR-UE and / or the capabilities of the VMR-UE based on the indication information in the NAS request message and / or the indication information in the subscription information. The subscription information may be stored in the UDM, and the VMR-AMF may obtain the subscription information of the VMR-UE from the UDM.

[0438] After the VMR-AMF determines the type of the VMR-UE and / or the capabilities of the VMR-UE, the type of the VMR-UE and / or the capabilities of the VMR-UE may be stored in the UE context.

[0439] Step 1103: The VMR-AMF sends a NAS response message to the VMR-UE. Correspondingly, the VMR-UE receives the NAS response message.

[0440] The NAS response message may be a registration acceptance message or a service response message.

[0441] Step 1104a, the VMR-gNB sends a connection establishment request message to the VMR-UE. Correspondingly, the VMR-UE receives the connection establishment request message.

[0442] The connection establishment request message is used to request the VMR-UE to initiate an N2 wireless backhaul link.

[0443] Step 1104b, the VMR-UE sends a PDU session establishment request message to the VMR-AMF. Correspondingly, the VMR-AMF receives the PDU session establishment request message.

[0444] The PDU session establishment request message includes a PDU session ID, and optionally also includes indication information, where the indication information is used to indicate that the PDU session is used to establish an N2 wireless backhaul link.

[0445] Step 1105a, VMR-AMF sends a query request to NRF. Correspondingly, NRF receives the query request.

[0446] The query request carries the location information of the VMR-UE and the NF type, where the NF type is used to indicate the AMF accessed via the N2 wireless backhaul link. The query request is used to query the identification information of the AMF that can be accessed via the N2 wireless backhaul link.

[0447] As an implementation method, the VMR-AMF may determine the type of the VMR-UE based on the indication information in the NAS request message and / or the indication information in the subscription information from the UDM, and then trigger the VMR-AMF to send a query request to the NRF based on the type of the VMR-UE. Optionally, after the VMR-AMF determines the type of the VMR-UE, the type of the VMR-UE may be stored in the UE context.

[0448] As another implementation method, the VMR-AMF may determine the type of the VMR-UE based on the indication information in the NAS request message and / or the indication information in the subscription information from the UDM, and then trigger the VMR-AMF to send a query request to the NRF based on the capabilities of the VMR-UE. Optionally, after the VMR-AMF determines the capabilities of the VMR-UE, the capabilities of the VMR-UE may be stored in the UE context.

[0449] As another implementation method, the VMR-AMF may trigger the VMR-AMF to send a query request to the NRF based on the indication information in the NAS request message for requesting the identification information of the AMF accessed via the wireless backhaul link.

[0450] Step 1105b, the NRF sends a query response to the VMR-AMF. Accordingly, the VMR-AMF receives the query response.

[0451] The query response carries the identification information of AMF-1 and the service area of ​​the AMF-1, and the service area may be a TA list.

[0452] Step 1106, VMR-AMF selects the SMF that serves the PDU session.

[0453] Step 1107: VMR-AMF sends a PDU session context establishment request to SMF. Correspondingly, SMF receives the PDU session context establishment request.

[0454] The PDU session context establishment request includes the identification information of AMF-1, and the AMF-1 is the AMF used for the N2 wireless backhaul link queried by the VMR-AMF.

[0455] For example, if the indication information is carried in step 1104b, VMR-AMF determines that the PDU session is used to establish the N2 wireless backhaul link based on the indication information carried in step 1104b, so VMR-AMF carries the identification information of AMF-1 in the PDU session context establishment request and sends it to SMF. Alternatively, VMR-AMF can determine that the PDU session is used to establish the N2 wireless backhaul link based on the type of VMR-UE and / or the capabilities of VMR-UE contained in the UE context, and carries the identification information of AMF-1 in the PDU session context establishment request and sends it to SMF (for example, when the indication information is not included in step 1104b).

[0456] Exemplarily, the PDU session context establishment request may be a service operation Nsmf_PDUSession_CreateSMContext Request called by the VMR-AMF.

[0457] SMF selects the appropriate UPF based on the identification information of AMF-1. At the same time, SMF also allocates an IP address to the VMR-UE.

[0458] Among them, if the identification information of VMR-AMF-1 is the address of VMR-AMF-1, then SMF can directly select a suitable UPF according to the address information. If the identification information of VMR-AMF-1 is the domain name corresponding to VMR-AMF-1 or the GUAMI of VMR-AMF-1, SMF can query the address of VMR-AMF-1 corresponding to the domain name or GUAMI through NRF, and then select a suitable UPF according to the address information.

[0459] Step 1108a, SMF sends an N4 session establishment request to UPF. Correspondingly, UPF receives the N4 session establishment request.

[0460] The N4 session establishment request includes a PDR and a FAR.

[0461] UPF identifies data packets belonging to sessions or service data flows based on the PDR sent by SMF, and processes service messages based on the FAR provided by SMF.

[0462] Step 1108b, UPF sends an N4 session establishment response to SMF. Correspondingly, SMF receives the N4 session establishment response.

[0463] Step 1109: SMF sends a PDU session context establishment response to VMR-AMF. Accordingly, VMR-AMF receives the PDU session context establishment response.

[0464] The PDU session context establishment response includes a PDU session establishment acceptance message, and the PDU session establishment acceptance message includes the IP address of the VMR-UE and the identification information of the AMF-1.

[0465] Exemplarily, the PDU session context establishment response may be a service operation Nsmf_PDUSession_CreateSMContext Response called by the SMF.

[0466] Step 1110: VMR-AMF sends a PDU session establishment accept message to VMR-UE. Correspondingly, VMR-UE receives the PDU session establishment accept message.

[0467] Step 1111, the VMR-UE sends a connection establishment response message to the VMR-gNB. Correspondingly, the VMR-gNB receives the connection establishment response message.

[0468] The connection establishment response message includes the IP address of the VMR-UE and the identification information of the AMF-1.

[0469] Among them, if the identification information of AMF-1 is the domain name corresponding to AMF-1 or the GUAMI of AMF-1, the VMR-UE can query the address of AMF-1 corresponding to the domain name or GUAMI through the DNS system.

[0470] After step 1111, the VMR-gNB and AMF-1 can forward the N2 message through the PDU session. For the specific process, please refer to Figure 4 Description of embodiments.

[0471] Step 1112: The VMR-UE moves, and the VMR-AMF determines that the VMR-UE has moved out of the service area of ​​AMF-1, and determines that the N2 wireless backhaul link needs to perform an AMF update.

[0472] Since the VMR-UE is registered with VMR-AMF, VMR-AMF can monitor the real-time location of VMR-UE, and VMR-AMF obtains the service area of ​​AMF-1 in the above step 1105b. Therefore, when the VMR-UE moves, VMR-AMF first obtains the latest location of VMR-UE and determines whether the latest location has moved out of the service area of ​​AMF-1. If it has moved out, it is determined that the N2 wireless backhaul link needs to perform AMF update.

[0473] refer to Fig.10 , which is a schematic diagram of VMR movement. When VMR moves, VMR-UE moves out of the service area of ​​AMF-1 and enters the service area of ​​AMF-2.

[0474] Step 1113a, VMR-AMF sends a query request to NRF. Correspondingly, NRF receives the query request.

[0475] The query request carries the location information of the VMR-UE and the NF type, where the NF type is used to indicate the AMF accessed via the N2 wireless backhaul link. The query request is used to query the identification information of the AMF that can be accessed via the N2 wireless backhaul link.

[0476] Specifically, the VMR-AMF determines to send a query request to the NRF according to the type of VMR-UE and / or the capability of the VMR-UE contained in the context information of the UE.

[0477] Step 1113b, NRF sends a query response to VMR-AMF. Correspondingly, VMR-AMF receives the query response.

[0478] The query response carries the identification information of AMF-2 and the service area of ​​the AMF-2, and the service area may be a TA list.

[0479] Step 1114: VMR-AMF sends a PDU session modification request message to SMF. Correspondingly, SMF receives the PDU session modification request message.

[0480] The PDU session modification request message includes the identification information of AMF-2.

[0481] Step 1115, SMF determines whether it is necessary to trigger an update of PSA based on the identification information of AMF-2.

[0482] If the SMF determines based on the identification information of VMR-AMF-2 that the PSA access path based on VMR-AMF-2 for the current session is not optimized, for example, the latency requirement of the wireless backhaul link cannot be met, it is necessary to trigger the update of the PSA. For example, the process of updating the PSA can be the following:

[0483] 1) If the SSC corresponding to the current PDU session is mode 3, SMF can initiate a session modification process, which can trigger the VMR-UE to initiate a new session establishment. That is, the VMR-UE subsequently accesses VMR-AMF-2 through the anchor point of the new session.

[0484] 2) SMF selects a new PSA for the current PDU session and inserts ULCL UPF or BP to optimize the user plane path for accessing VMR-AMF-2. That is, the subsequent VMR-UE accesses VMR-AMF-2 through the new PSA.

[0485] Among them, if the identification information of VMR-AMF-2 is the address of VMR-AMF-2, then SMF can directly select a suitable PSA according to the address information. If the identification information of VMR-AMF-2 is the domain name corresponding to VMR-AMF-2 or the GUAMI of VMR-AMF-2, SMF can query the address of VMR-AMF-2 corresponding to the domain name or GUAMI through NRF, and then select a suitable PSA according to the address information.

[0486] Step 1116: SMF sends a PDU session modification message to the VMR-UE. Correspondingly, the VMR-UE receives the PDU session modification message.

[0487] The PDU session modification message includes the identification information of AMF-2 and, optionally, also includes the new IP address allocated by SMF to the VMR-UE.

[0488] In step 1117, the VMR-UE sends a connection modification message to the VMR-gNB. Accordingly, the VMR-gNB receives the connection modification message.

[0489] The connection modification message is used to modify the N2 wireless backhaul link.

[0490] The connection modification message includes the identification information of AMF-2 and, optionally, the new IP address allocated by SMF to the VMR-UE.

[0491] In the above scheme, the AMF accessed by VMR-gNB through the N2 wireless backhaul link is different from the VMR-AMF currently accessed by VMR-UE. The AMF supporting the access of N2 wireless backhaul link is selected according to the current location of VMR-UE, and the update of N2 wireless backhaul link can be realized during the movement of VMR.

[0492] Fig.12 A flow chart of a communication method provided in an embodiment of the present application. The method comprises the following steps:

[0493] Step 1200, AMF-1 supporting the N2 wireless backhaul link sends a NF registration request to the NRF. Accordingly, the NRF receives the NF registration request.

[0494] The NF registration request carries the identification information of AMF-1, the service area of ​​AMF-1 and indication information. The service area of ​​AMF-1 can be represented by a TA list, and the indication information is used to indicate that the AMF-1 can be accessed through the N2 wireless backhaul link.

[0495] Similarly, for other AMFs, such as AMF-2, etc., NF registration requests can also be sent to NRF, which will not be repeated here.

[0496] Step 1201 to step 1208b, same Fig.11 Steps 1101 to 1108b of the embodiment.

[0497] That is, steps 1201-1203, 1204a-1204b, 1205a-1205b, 1206-1207, 1208a-1208b and Fig.11 The steps 1101 to 1103, 1104a to 1104b, 1105a to 1105b, 1106 to 1107, and 1108a to 1108b in the embodiment correspond to each other.

[0498] Step 1209: SMF sends a PDU session context establishment response to VMR-AMF. Accordingly, VMR-AMF receives the PDU session context establishment response.

[0499] The PDU session context establishment response includes a PDU session establishment acceptance message, and the PDU session establishment acceptance message includes the IP address of the VMR-UE, the identification information of the AMF-1 and the service area of ​​the AMF-1.

[0500] Exemplarily, the PDU session context establishment response may be a service operation Nsmf_PDUSession_CreateSMContext Response called by the SMF.

[0501] Step 1210: VMR-AMF sends a PDU session establishment accept message to VMR-UE. Correspondingly, VMR-UE receives the PDU session establishment accept message.

[0502] The PDU session establishment acceptance message includes the IP address of the VMR-UE, the identification information of the AMF-1 and the service area of ​​the AMF-1.

[0503] Step 1211: The VMR-UE sends a connection establishment response message to the VMR-gNB. Accordingly, the VMR-gNB receives the connection establishment response message.

[0504] The connection establishment response message includes the IP address of the VMR-UE, the identification information of the AMF-1 and the service area of ​​the AMF-1.

[0505] Among them, if the identification information of AMF-1 is the domain name corresponding to AMF-1 or the GUAMI of AMF-1, the VMR-UE can query the address of AMF-1 corresponding to the domain name or GUAMI through the DNS system.

[0506] After step 1211, the VMR-gNB and AMF-1 can forward the N2 message through the PDU session. For the specific process, please refer to Figure 4 Description of embodiments.

[0507] In step 1212, the VMR-UE moves, and the VMR-gNB determines that the VMR-UE has moved out of the service area of ​​AMF-1, and determines that the N2 wireless backhaul link needs to perform an AMF update.

[0508] refer to Fig.10 , which is a schematic diagram of VMR movement. When VMR moves, VMR-UE moves out of the service area of ​​AMF-1 and enters the service area of ​​AMF-2.

[0509] Step 1213a, the VMR-gNB sends a RAN configuration update request message to the VMR-UE. Correspondingly, the VMR-UE receives the RAN configuration update request message.

[0510] The RAN configuration update request message includes the location information and indication information of the VMR-gNB, and the indication information is used to request the discovery of AMF.

[0511] Among them, the location information of VMR-gNB can be represented by the TAI where the VMR-UE or VMR-gNB is currently located.

[0512] Step 1213b, VMR-UE sends the RAN configuration update request message to AMF-1 through the PDU session.

[0513] The specific process of sending a RAN configuration update request message to AMF-1 through a PDU session can be found in Figure 4 Description of embodiments.

[0514] Step 1214a, AMF-1 sends a query request to NRF. Correspondingly, NRF receives the query request.

[0515] The query request carries the location information of the VMR-gNB and the NF type, where the NF type is used to indicate the AMF accessed through the N2 wireless backhaul link. The query request is used to query the identification information of the AMF that can be accessed through the N2 wireless backhaul link.

[0516] Specifically, AMF-1 determines to send a query request to the NRF according to the type of VMR-UE and / or the capability of the VMR-UE contained in the context information of the UE.

[0517] Step 1214b, the NRF sends a query response to the VMR-AMF. Accordingly, the VMR-AMF receives the query response.

[0518] The query response carries the identification information of AMF-2 and the service area of ​​the AMF-2, and the service area may be a TA list.

[0519] NRF may determine AMF-2 with reference to the location information of VMR-gNB, or may determine AMF-2 without reference to the location information of VMR-gNB. This application does not limit this.

[0520] Step 1215a, AMF-1 sends a RAN configuration update response message to the VMR-UE via the PDU session. Correspondingly, the VMR-UE receives the RAN configuration update response message.

[0521] The RAN configuration update response message includes the identification information of AMF-2 and the service area of ​​the AMF-2.

[0522] The specific process of sending a RAN configuration update response message to a VMR-UE through a PDU session can be found in Figure 4 Description of embodiments.

[0523] Step 1215b, the VMR-UE sends a RAN configuration update response message to the VMR-gNB. Correspondingly, the VMR-gNB receives the RAN configuration update response message.

[0524] VMR-gNB obtains the identification information of AMF-2 and the service area of ​​AMF-2 from the RAN configuration update response message.

[0525] Subsequently, the VMR-gNB can access AMF-2 through the newly created PDU session of the VMR-UE based on the identification information of AMF-2.

[0526] In the above step 1212, after the VMR-gNB determines that the VMR-UE has moved out of the service area of ​​AMF-1, it triggers AMF-1 to re-acquire the identification information of AMF-2 corresponding to the latest location of VMR-gNB, and sends the identification information of AMF-2 to VMR-gNB. For details, refer to the above steps 1213a~1213b, 1214a~1214b and 1215a~1215b. As another implementation method, after step 1212, the VMR-gNB may also trigger the VMR-AMF to re-acquire the identification information of the AMF-2 corresponding to the latest position of the VMR-gNB, and send the identification information of the AMF-2 to the VMR-gNB. For example, the VMR-gNB sends a request message to the VMR-UE to request a new AMF for N2 wireless link backhaul, and then the VMR-UE sends a request message to the VMR-AMF to request a new AMF for N2 wireless link backhaul. Then, the VMR-AMF obtains the identification information of the AMF-2 corresponding to the latest position of the VMR-gNB or VMR-UE by querying the NRF, and sends the identification information of the AMF-2 to the VMR-UE, and the VMR-UE sends the identification information of the AMF-2 to the VMR-gNB.

[0527] In the above scheme, the AMF accessed by VMR-gNB through the N2 wireless backhaul link is different from the VMR-AMF currently accessed by VMR-UE. The AMF supporting the access of N2 wireless backhaul link is selected according to the current location of VMR-UE, and the update of N2 wireless backhaul link can be realized during the movement of VMR.

[0528] It is understandable that in order to implement the functions in the above embodiments, the terminal device, the first mobility management network element, the session management network element or the vehicle-mounted relay device includes hardware structures and / or software modules corresponding to the execution of each function. Those skilled in the art should easily realize 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 the form of hardware or computer software driving hardware depends on the specific application scenario and design constraints of the technical solution.

[0529] Fig.13 and Fig.14A schematic diagram of the structure of a possible communication device provided for an embodiment of the present application. These communication devices can be used to implement the functions of the terminal device, the first mobility management network element, the session management network element or the vehicle-mounted relay device in the above method embodiment, and thus can also achieve the beneficial effects possessed by the above method embodiment. In an embodiment of the present application, the communication device can be a terminal device, a first mobility management network element, a session management network element or a vehicle-mounted relay device, and can also be a module (such as a chip) applied to a terminal device, a first mobility management network element, a session management network element or a vehicle-mounted relay device.

[0530] Fig.13 The communication device 1300 shown includes a processing unit 1310 and a transceiver unit 1320. The communication device 1300 is used to implement the functions of the terminal device, the first mobility management network element, the session management network element or the vehicle-mounted relay device in the above method embodiment.

[0531] When the communication device 1300 is used to implement the function of the terminal device in the above method embodiment, the transceiver unit 1320 is used to receive a first message from a first mobility management network element, wherein the first message includes identification information of a second mobility management network element; and send the identification information of the second mobility management network element to an access network device; wherein the terminal device and the access network device constitute a vehicle-mounted relay device, the first mobility management network element is a mobility management network element registered by the terminal device, and the second mobility management network element is a mobility management network element accessed by the access network device through a wireless backhaul link.

[0532] In a possible implementation method, the transceiver unit 1320 is further configured to send a NAS request message to the first mobility management network element before receiving the first message from the first mobility management network element; then the first message is a NAS response message.

[0533] In a possible implementation method, the NAS request message includes first indication information, and the first indication information is used to indicate at least one of the following: the type of the terminal device, the type indicating that the terminal device is a vehicle-mounted relay terminal device jointly installed with the access network device; the capability of the terminal device, the capability being that the terminal device has the ability to establish a wireless backhaul link using a PDU session; and identification information of a mobility management network element requested to be accessed through the wireless backhaul link.

[0534] In a possible implementation method, the transceiver unit 1320 is further configured to receive a session establishment acceptance message, wherein the session establishment acceptance message includes the address information of the terminal device; and send the address information of the terminal device to the access network device.

[0535] In a possible implementation method, the transceiver unit 1320 is also used to send a session establishment request message to the first mobility management network element before receiving a first message from the first mobility management network element, and the session establishment request message includes identification information of the PDU session; then the first message is a session establishment acceptance message.

[0536] In a possible implementation method, the session establishment request message also includes second indication information, and the second indication information is used to indicate that the PDU session is used to establish a wireless backhaul link.

[0537] In a possible implementation method, the session establishment acceptance message also includes address information of the terminal device; and the transceiver unit 1320 is further configured to send the address information of the terminal device to the access network device.

[0538] In a possible implementation method, the second mobility management network element and the first mobility management network element are the same mobility management network element.

[0539] In a possible implementation method, the second mobility management network element and the first mobility management network element are different mobility management network elements, and the first message further includes a service area of ​​the second mobility management network element.

[0540] In a possible implementation method, the transceiver unit 1320 is also used to receive a second message, where the second message includes identification information of a third mobility management network element; and send the identification information of the third mobility management network element to the access network device, where the third mobility management network element is a mobility management network element accessed by the access network device through a wireless backhaul link or a mobility management network element newly registered for the terminal device.

[0541] In a possible implementation method, the second message is a configuration update message or a session modification message.

[0542] When the communication device 1300 is used to implement the function of the first mobility management network element in the above method embodiment, the processing unit 1310 is used to obtain the identification information of the second mobility management network element; the transceiver unit 1320 is used to send a first message to the terminal device, and the first message includes the identification information of the second mobility management network element; wherein the terminal device and the access network device constitute a vehicle-mounted relay device, the first mobility management network element is the mobility management network element registered by the terminal device, and the second mobility management network element is the mobility management network element accessed by the access network device through a wireless backhaul link.

[0543] In a possible implementation method, the transceiver unit 1320 is further used to receive a NAS request message from the terminal device before the processing unit 1310 obtains the identification information of the second mobility management network element; then the first message is a NAS response message.

[0544] In a possible implementation method, the NAS request message includes first indication information; the processing unit 1310 is used to obtain the identification information of the second mobility management network element, specifically including: used to obtain the identification information of the second mobility management network element according to the first indication information; wherein the first indication information is used to indicate at least one of the following: the type of the terminal device, the type indicating that the terminal device is a vehicle-mounted relay terminal device jointly set up with the access network device; the capability of the terminal device, the capability being that the terminal device has the ability to establish a wireless backhaul link using a PDU session; the identification information of the mobility management network element requested to be accessed through the wireless backhaul link.

[0545] In a possible implementation method, the transceiver unit 1320 is also used to receive first indication information from a data management network element; the processing unit 1310 is used to obtain identification information of a second mobility management network element, specifically including: used to obtain identification information of the second mobility management network element according to the first indication information; wherein the first indication information is used to indicate at least one of the following: the type of the terminal device, the type indicating that the terminal device is a vehicle-mounted relay terminal device jointly provided with the access network device; the capability of the terminal device, the capability being that the terminal device has the ability to establish a wireless backhaul link using a PDU session.

[0546] In a possible implementation method, the transceiver unit 1320 is further configured to send a session establishment acceptance message to the terminal device, where the session establishment acceptance message includes address information of the terminal device.

[0547] In a possible implementation method, the transceiver unit 1320 is also used to receive a session establishment request message from the terminal device before the processing unit 1310 obtains the identification information of the second mobility management network element, and the session establishment request message includes the identification information of the PDU session; then the first message is a session establishment acceptance message.

[0548] In a possible implementation method, the session establishment request message also includes second indication information, and the second indication information is used to indicate that the PDU session is used to establish a wireless backhaul link; the processing unit 1310 is used to obtain the identification information of the second mobility management network element, specifically including: being used to obtain the identification information of the second mobility management network element according to the second indication information.

[0549] In a possible implementation method, the session establishment acceptance message further includes address information of the terminal device.

[0550] In a possible implementation method, the second mobility management network element and the first mobility management network element are the same mobility management network element.

[0551] In a possible implementation method, the processing unit 1310 is used to obtain the identification information of the second mobility management network element, specifically including: sending a query request to the network storage function network element through the transceiver unit 1320, the query request including the location information of the terminal device, and the query request is used to query the identification information of the mobility management network element that can be accessed through the wireless backhaul link; and receiving a query response from the network storage function network element, the query response including the identification information of the second mobility management network element.

[0552] In a possible implementation method, the first message also includes a service area of ​​the second mobility management network element.

[0553] In a possible implementation method, the transceiver unit 1320 is also used to send a configuration update message to the terminal device, and the configuration update message includes identification information of a third mobility management network element. The third mobility management network element is a mobility management network element accessed by the access network device through a wireless backhaul link or a mobility management network element newly registered for the terminal device.

[0554] When the communication device 1300 is used to implement the function of the first mobility management network element in the above method embodiment, the transceiver unit 1320 is used to send a query request to the network storage function network element, the query request includes the location information of the terminal device, and the query request is used to query the identification information of the mobility management network element that can be accessed through the wireless backhaul link; receive a query response from the network storage function network element, the query response includes the identification information of the second mobility management network element, the terminal device and the access network device constitute a vehicle-mounted relay device, and the second mobility management network element is the mobility management network element accessed by the access network device through the wireless backhaul link.

[0555] When the communication device 1300 is used to implement the function of the session management network element in the above method embodiment, the transceiver unit 1320 is used to receive the identification information of the second mobility management network element from the first mobility management network element; and send the identification information of the second mobility management network element to the terminal device; wherein the terminal device and the access network device constitute a vehicle-mounted relay device, the first mobility management network element is the mobility management network element registered by the terminal device, and the second mobility management network element is the mobility management network element accessed by the access network device through a wireless backhaul link.

[0556] In a possible implementation method, the transceiver unit 1320 is used to receive identification information of a second mobility management network element from a first mobility management network element, specifically including: receiving a session context establishment request message from the first mobility management network element, the session context establishment request message including the identification information of the second mobility management network element; the transceiver unit 1320 is used to send the identification information of the second mobility management network element to a terminal device, specifically including: sending a session establishment acceptance message to the terminal device, the session establishment acceptance message including the identification information of the second mobility management network element.

[0557] In a possible implementation method, the session establishment acceptance message further includes address information of the terminal device and / or a service area of ​​the second mobility management network element.

[0558] In a possible implementation method, the transceiver unit 1320 is also used to send a session modification message to the terminal device, and the session modification message includes identification information of a third mobility management network element. The third mobility management network element is a mobility management network element accessed by the access network device through a wireless backhaul link or a mobility management network element newly registered for the terminal device.

[0559] In a possible implementation method, the second mobility management network element and the first mobility management network element are the same mobility management network element.

[0560] When the communication device 1300 is used to implement the function of the vehicle-mounted relay device in the above method embodiment, the transceiver unit 1320 is used to receive a first message from a first mobility management network element, and the first message includes identification information of a second mobility management network element; the processing unit 1310 accesses the second mobility management network element through a protocol data unit PDU session; wherein the first mobility management network element is the mobility management network element registered by the vehicle-mounted relay device.

[0561] In a possible implementation method, the transceiver unit 1320 is further configured to send a NAS request message to the first mobility management network element before receiving the first message from the first mobility management network element; then the first message is a NAS response message.

[0562] In a possible implementation method, the NAS request message includes first indication information, and the first indication information is used to indicate at least one of the following: the type of the vehicle-mounted relay device, the type indicating that the vehicle-mounted terminal device is equipped with a vehicle-mounted terminal device and a vehicle-mounted access network device; the capability of the vehicle-mounted relay device, the capability indicating that the vehicle-mounted relay device has the ability to establish a wireless backhaul link using a PDU session; and the identification information of the mobility management network element requested to be accessed through the wireless backhaul link.

[0563] In a possible implementation method, the transceiver unit 1320 is further configured to receive a session establishment acceptance message, where the session establishment acceptance message includes address information of the vehicle-mounted relay device.

[0564] In a possible implementation method, the transceiver unit 1320 is also used to send a session establishment request message to the first mobility management network element before receiving a first message from the first mobility management network element, and the session establishment request message includes identification information of the PDU session; then the first message is a session establishment acceptance message.

[0565] In a possible implementation method, the session establishment request message also includes second indication information, and the second indication information is used to indicate that the PDU session is used to establish a wireless backhaul link.

[0566] In a possible implementation method, the session establishment acceptance message also includes address information of the vehicle-mounted relay device.

[0567] In a possible implementation method, the second mobility management network element and the first mobility management network element are the same mobility management network element.

[0568] In a possible implementation method, the second mobility management network element and the first mobility management network element are different mobility management network elements, and the first message further includes a service area of ​​the second mobility management network element.

[0569] In a possible implementation method, the transceiver unit 1320 is also used to receive a second message, wherein the second message includes identification information of a third mobility management network element, and the third mobility management network element is a mobility management network element accessed by the access network device through a wireless backhaul link or a mobility management network element newly registered for the terminal device.

[0570] In one possible implementation method, the processing unit 1310 is also used to determine that the vehicle-mounted relay device has moved out of the service area of ​​the second mobility management network element before the transceiver unit 1320 receives the second message; the transceiver unit 1320 is also used to send a configuration update request message to the second mobility management network element, the configuration update request message including the location information of the vehicle-mounted relay device, and the configuration update request message is used to request the discovery of the mobility management network element.

[0571] In a possible implementation method, the configuration update request message further includes third indication information, and the third indication information is used to request discovery of a mobility management network element.

[0572] In a possible implementation method, the second message is a configuration update message or a session modification message.

[0573] For a more detailed description of the processing unit 1310 and the transceiver unit 1320, reference may be made to the relevant description in the above method embodiment, which will not be repeated here.

[0574] Fig.14 The communication device 1400 shown includes a processor 1410 and an interface circuit 1420. The processor 1410 and the interface circuit 1420 are coupled to each other. It is understood that the interface circuit 1420 can be a transceiver or an input-output interface. Optionally, the communication device 1400 may also include a memory 1430 for storing instructions executed by the processor 1410 or storing input data required by the processor 1410 to execute instructions or storing data generated after the processor 1410 executes instructions.

[0575] When the communication device 1400 is used to implement the above method embodiment, the processor 1410 is used to implement the function of the above processing unit 1310, and the interface circuit 1420 is used to implement the function of the above transceiver unit 1320.

[0576] It is understood that the processor in the embodiments of the present application may be a central processing unit (CPU), or 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.

[0577] The method steps in the embodiments of the present application can be implemented by hardware or by a processor executing software instructions. The software instructions can be composed of corresponding software modules, and the software modules can be stored in a random access memory, a flash memory, a read-only memory, a programmable read-only memory, an erasable programmable read-only memory, an electrically erasable programmable read-only memory, a register, a hard disk, a mobile hard disk, a compact disc read-only memory (CD-ROM) or any other form of storage medium 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. Of course, the storage medium can also be a component of the processor. The processor and the storage medium can be located in an ASIC. In addition, the ASIC can be located in a terminal device, a first mobility management network element, a session management network element, or a vehicle-mounted relay device. Of course, the processor and the storage medium can also exist as discrete components in an access network device or a terminal.

[0578] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer programs or instructions. A computer program refers to a set of instructions for each step of an electronic computer or other device with message processing capability, usually written in a certain programming language, and running on a certain target architecture. When the computer program or instruction is loaded and executed on a computer, the process or function described in the embodiment of the present application is executed in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network or other programmable device. The computer program or instruction may be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium, for example, the computer program or instruction may be transmitted from one website site, computer, server or data center to another website site, computer, server or data center by wired or wireless means. The computer-readable storage medium may be any available medium that a computer can access 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, a hard disk, or a 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 non-volatile storage medium, or may include both volatile and non-volatile types of storage media.

[0579] In the various embodiments of the present application, unless otherwise specified or provided for in any logical conflict, the terms and / or descriptions between the different embodiments are consistent and may be referenced to each other, and the technical features in the different embodiments may be combined to form new embodiments according to their inherent logical relationships.

[0580] In this application, "at least one" means one or more, and "more than one" 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.

[0581] It is understood that the various numbers involved in the embodiments of the present application are only for the convenience of description and are not used to limit the scope of the embodiments of the present application. The size of the sequence number of the above-mentioned processes does not mean the order of execution, and the execution order of each process should be determined by its function and internal logic.

Claims

1. A communication method, characterized in that: Applied to a terminal device or a module of a terminal device, the method comprises: receiving a first message from a first mobility management network element, wherein the first message includes identification information of a second mobility management network element; Sending identification information of the second mobility management network element to the access network device; Among them, the terminal device and the access network device constitute a vehicle-mounted relay device, the first mobility management network element is the mobility management network element registered by the terminal device, and the second mobility management network element is the mobility management network element accessed by the access network device through a wireless backhaul link.

2. The method according to claim 1, characterized in that Before receiving the first message from the first mobility management network element, the method further includes: Sending a NAS request message to the first mobility management network element; Then the first message is a NAS response message.

3. The method according to claim 2, characterized in that The NAS request message includes first indication information, where the first indication information is used to indicate at least one of the following: The type of the terminal device, the type indicating that the terminal device is a vehicle-mounted relay terminal device jointly provided with the access network device; The capability of the terminal device, wherein the capability is that the terminal device has the ability to establish a wireless backhaul link using a protocol data unit (PDU) session; Requests identification information of the mobility management network element accessed via the wireless backhaul link.

4. The method according to claim 2 or 3, characterized in that The method further comprises: receiving a session establishment acceptance message, wherein the session establishment acceptance message includes address information of the terminal device; Send the address information of the terminal device to the access network device.

5. The method according to claim 1, characterized in that Before receiving the first message from the first mobility management network element, the method further includes: Sending a session establishment request message to the first mobility management network element, where the session establishment request message includes identification information of the PDU session; Then the first message is a session establishment accept message.

6. The method according to claim 5, characterized in that The session establishment request message also includes second indication information, where the second indication information is used to indicate that the PDU session is used to establish a wireless backhaul link.

7. The method according to claim 5 or 6, characterized in that The session establishment acceptance message also includes address information of the terminal device; The method further comprises: Send the address information of the terminal device to the access network device.

8. The method according to any one of claims 1 to 7, characterized in that The second mobility management network element and the first mobility management network element are the same mobility management network element.

9. The method according to any one of claims 1 to 7, characterized in that The second mobility management network element and the first mobility management network element are different mobility management network elements, and the first message further includes a service area of ​​the second mobility management network element.

10. The method according to any one of claims 1 to 9, characterized in that The method further comprises: receiving a second message, wherein the second message includes identification information of a third mobility management network element; The identification information of the third mobility management network element is sent to the access network device, where the third mobility management network element is a mobility management network element accessed by the access network device through a wireless backhaul link or a mobility management network element newly registered by the terminal device.

11. The method according to claim 10, characterized in that The second message is a configuration update message or a session modification message.

12. A communication method, characterized in that: Applied to the first mobility management network element or a module of the first mobility management network element, the method comprises: Acquiring identification information of a second mobility management network element; Sending a first message to a terminal device, where the first message includes identification information of the second mobility management network element; Among them, the terminal device and the access network device constitute a vehicle-mounted relay device, the first mobility management network element is the mobility management network element registered by the terminal device, and the second mobility management network element is the mobility management network element accessed by the access network device through a wireless backhaul link.

13. The method according to claim 12, characterized in that Before obtaining the identification information of the second mobility management network element, the method further includes: Receiving a NAS request message from the terminal device; Then the first message is a NAS response message.

14. The method according to claim 13, characterized in that The NAS request message includes first indication information; The acquiring identification information of the second mobility management network element includes: Acquire identification information of the second mobility management network element according to the first indication information; The first indication information is used to indicate at least one of the following: The type of the terminal device, the type indicating that the terminal device is a vehicle-mounted relay terminal device jointly provided with the access network device; The capability of the terminal device, wherein the capability is that the terminal device has the ability to establish a wireless backhaul link using a protocol data unit (PDU) session; Requests identification information of the mobility management network element accessed via the wireless backhaul link.

15. The method according to claim 12, characterized in that The method further comprises: Receiving first indication information from a data management network element; The acquiring identification information of the second mobility management network element includes: Acquire identification information of the second mobility management network element according to the first indication information; The first indication information is used to indicate at least one of the following: The type of the terminal device, the type indicating that the terminal device is a vehicle-mounted relay terminal device jointly provided with the access network device; The capability of the terminal device, wherein the capability is that the terminal device has the ability to establish a wireless backhaul link using a PDU session.

16. The method according to any one of claims 13 to 15, characterized in that The method further comprises: A session establishment acceptance message is sent to the terminal device, where the session establishment acceptance message includes address information of the terminal device.

17. The method according to claim 12, characterized in that Before obtaining the identification information of the second mobility management network element, the method further includes: receiving a session establishment request message from the terminal device, wherein the session establishment request message includes identification information of the PDU session; Then the first message is a session establishment accept message.

18. The method according to claim 17, characterized in that The session establishment request message further includes second indication information, where the second indication information is used to indicate that the PDU session is used to establish a wireless backhaul link; The acquiring identification information of the second mobility management network element includes: According to the second indication information, identification information of the second mobility management network element is acquired.

19. The method according to claim 17 or 18, characterized in that The session establishment acceptance message also includes address information of the terminal device.

20. The method according to any one of claims 12 to 19, characterized in that The second mobility management network element and the first mobility management network element are the same mobility management network element.

21. The method according to any one of claims 12 to 19, characterized in that The acquiring identification information of the second mobility management network element includes: Sending a query request to a network storage function network element, the query request including the location information of the terminal device, the query request being used to query identification information of a mobility management network element accessible through a wireless backhaul link; A query response is received from the network storage function network element, where the query response includes identification information of the second mobility management network element.

22. The method according to claim 21, characterized in that The first message also includes a service area of ​​the second mobility management network element.

23. The method according to any one of claims 12 to 22, characterized in that The method further comprises: A configuration update message is sent to the terminal device, wherein the configuration update message includes identification information of a third mobility management network element, where the third mobility management network element is a mobility management network element accessed by the access network device through a wireless backhaul link or a mobility management network element newly registered by the terminal device.

24. A communication device, characterized in that: Comprising a module for executing the method described in any one of claims 1 to 11, or the method described in any one of claims 12 to 23.

25. A communication device, characterized in that: The invention comprises a processor and an interface circuit, wherein the processor is used to communicate with other devices through the interface circuit and execute the method described in any one of claims 1 to 11 or the method described in any one of claims 12 to 23.

26. A computer program product, characterized in that The computer program product comprises instructions, which, when executed on a processor, cause the processor to perform the method according to any one of claims 1 to 11 or the method according to any one of claims 12 to 23.

27. A computer-readable storage medium, characterized in that: The storage medium stores a computer program or instruction, and when the computer program or instruction is executed by the communication device, the method described in any one of claims 1 to 11, or the method described in any one of claims 12 to 23 is implemented.

28. A communication system, characterized in that: include: A device for accessing a network, and a terminal device for executing the method according to any one of claims 1 to 11; The access network device is used to receive identification information of a second mobility management network element from the terminal device.

29. The system of claim 28, wherein: The communication system further comprises a first mobility management network element for executing the method according to any one of claims 12 to 23.

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