Multicast / broadcast session management method and communication device

Abstract

The application provides a multicast / broadcast session management method and a communication device. The method comprises the following steps: a session management function network element sends first information to an intermediate session management function network element, wherein the first information comprises information of a first multicast / broadcast service; and the session management function network element receives second information from the intermediate session management function network element, wherein the second information is used for indicating that a first tunnel for transmitting data of the first multicast / broadcast service between an intermediate user plane function network element and a multicast / broadcast user plane function network element has been established. The technical solution can make the session management function network element know that the first tunnel has been established, thereby facilitating the optimization of a transmission path of the data of the first multicast / broadcast service by using the first tunnel, reducing the transmission delay of the multicast / broadcast service data and saving network transmission resources.

Description

Technical Field

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

[0002] With the development of mobile internet, mobile high-definition video services are experiencing a surge in popularity. Users are gradually shifting from traditional fixed-line TV viewing to watching popular programs via mobile phones and the mobile internet. Consequently, the impact of video services on mobile networks is becoming increasingly significant. Optimizing video service transmission through air interface multicasting can significantly reduce the impact of video traffic on mobile networks.

[0003] Currently, the 5th generation (5G) mobile communication networks can support multicast broadcast service (MBS). However, due to the limited service areas of the session management function (SMF) and user plane function (UPF), when a terminal device moves, an intermediate session management function (I-SMF) and an intermediate user plane function (I-UPF) are inserted, and when the terminal device's multicast / broadcast service data is transmitted through the terminal device's protocol data unit (PDU) session, the transmission path of the multicast / broadcast service data may be circuitous, resulting in wasted network resources and increased data transmission latency. Summary of the Invention

[0004] The present application provides a multicast / broadcast session management method and a communication device for optimizing the transmission path of multicast / broadcast service data, thereby saving network resources and reducing the transmission delay of multicast / broadcast service data.

[0005] In a first aspect, an embodiment of the present application provides a multicast / broadcast session management method, which can be executed by a session management function network element or by a component (such as a chip or circuit) configured in the session management function network element.

[0006] The method includes: a session management function network element sends first information to an intermediate session management function network element, the first information including information of a first multicast / broadcast service, the session management function network element being used to control a PDU session anchor point of a protocol data unit (PDU) session associated with a terminal device and the first multicast / broadcast service; the session management function network element receives second information from the intermediate session management function network element, the second information being used to indicate that a first tunnel has been established, the first tunnel being used to transmit data of the first multicast / broadcast service between the intermediate user plane function network element and the multicast / broadcast user plane function network element, and the intermediate session management function network element being used to control the intermediate user plane function network element.

[0007] In the above technical solution, the session management function network element sends the first information to the intermediate session management function network element. The intermediate session management function network element may send the second information to the session management function network element after the first tunnel between the intermediate user plane function network element and the multicast / broadcast user plane function network element is established, so that the session management function network element learns that the first tunnel has been established, thereby facilitating the use of the first tunnel to optimize the transmission path of the data of the first multicast / broadcast service, reduce the transmission delay of the multicast / broadcast service data, and save network transmission resources.

[0008] In a possible design of the first aspect, the first tunnel is a direct tunnel between the intermediate user plane functional network element and the multicast / broadcast user plane functional network element.

[0009] In a possible design of the first aspect, the first information includes first indication information, which is used to trigger the intermediate session management function network element to establish a first tunnel, or the first indication information is used to query the intermediate session management function network element whether the first tunnel has been established.

[0010] In a possible design of the first aspect, the second information includes information of the first multicast / broadcast service.

[0011] In a possible design of the first aspect, the information of the first multicast / broadcast service includes one or more of the following information: identification information of the first multicast / broadcast service, identification information of the regional session of the first multicast broadcast service, multicast / broadcast service quality QoS information of the first multicast / broadcast service, or unicast QoS information corresponding to the multicast / broadcast QoS information of the first multicast broadcast service.

[0012] In a possible design of the first aspect, the method further includes: the session management function network element receives multicast / broadcast capability information from the intermediate session management function network element, where the multicast / broadcast capability information is used to indicate whether the intermediate session management function network element supports multicast / broadcast; the session management function network element sends first information to the intermediate session management function network element, including: the session management function network element sends the first information to the intermediate session management function network element based on the multicast / broadcast capability information.

[0013] In the above technical solution, the session management function network element can confirm that the intermediate session management function network element supports multicast / broadcast based on the multicast / broadcast capability information of the intermediate session management function network element, and then send the first information to the intermediate session management function network element, so that the transmission path of the data of the first multicast / broadcast service can be optimized by establishing a first tunnel.

[0014] In a possible design of the first aspect, the method also includes: the session management function network element sends a first message to the PDU session anchor point based on the second information, and the first message is used to trigger the PDU session anchor point to release resources used to transmit data for the first multicast / broadcast service.

[0015] In a second aspect, an embodiment of the present application provides a multicast / broadcast session management method, which can be executed by an intermediate session management function network element, or by a component (such as a chip or circuit) configured in the intermediate session management function network element.

[0016] The method includes: an intermediate session management function network element receives first information from a session management function network element, the first information including information of a first multicast / broadcast service, and the session management function network element is used to control a PDU session anchor point of a protocol data unit (PDU) session associated with a terminal device and the first multicast / broadcast service; the intermediate session management function network element sends second information to the session management function network element based on the first information, the second information being used to indicate that a first tunnel has been established, the first tunnel being used to transmit data of the first multicast / broadcast service between the intermediate user plane function network element and the multicast / broadcast user plane function network element, and the intermediate session management function network element being used to control the intermediate user plane function network element.

[0017] In a possible design of the second aspect, the first tunnel is a direct tunnel between the intermediate user plane functional network element and the multicast / broadcast user plane functional network element.

[0018] In a possible design of the second aspect, the first information includes first indication information; the method also includes: the intermediate session management function network element establishes a first tunnel according to the first indication information, or queries whether the first tunnel has been established.

[0019] In a possible design of the second aspect, the second information includes information of the first multicast / broadcast service.

[0020] In a possible design of the second aspect, the information of the first multicast / broadcast service includes one or more of the following information: identification information of the first multicast / broadcast service, identification of the regional session of the first multicast / broadcast service, multicast / broadcast service quality QoS information of the first multicast / broadcast service, or unicast QoS information corresponding to the multicast-broadcast QoS information of the first multicast / broadcast service.

[0021] In a possible design of the second aspect, the method also includes: the intermediate session management function network element sends multicast / broadcast capability information of the intermediate session management function network element to the session management function network element, where the multicast / broadcast capability information is used to indicate whether the intermediate session management function network element supports multicast / broadcast.

[0022] In a possible design of the second aspect, the method also includes: the intermediate session management function network element sends a second message to the intermediate user plane function network element, and the second message is used to trigger the intermediate user plane function network element to configure resources for transmitting data of the first multicast / broadcast service.

[0023] For the beneficial effects of the method in the second aspect and any possible design thereof, please refer to the corresponding description of the first aspect and no further details will be given.

[0024] In a third aspect, an embodiment of the present application provides a communication device, which may have the functions of implementing a session management function network element or an intermediate session management function network element in the above aspects. The communication device may be a network device or a chip included in the network device.

[0025] The functions of the above-mentioned communication device can be implemented by hardware, or by hardware executing corresponding software. The hardware or software includes one or more modules, units or means corresponding to the above-mentioned functions.

[0026] In one possible design, the communication device includes a processing module and a transceiver module. The processing module is configured to support the communication device in executing the functions corresponding to the session management function network element in the above-mentioned aspects, or in executing the functions corresponding to the intermediate session management function network element in the above-mentioned aspects. The transceiver module is configured to support communication between the communication device and other communication devices. For example, when the communication device is a session management function network element, the transceiver module may send first information to the intermediate session management function network element. The communication device may also include a storage module, which is coupled to the processing module and stores program instructions and data necessary for the communication device. As an example, the processing module may be a processor, the communication module may be a transceiver, and the storage module may be a memory. The memory may be integrated with the processor or provided separately from the processor.

[0027] In another possible design, the communication device includes a processor and may also include a memory. The processor is coupled to the memory and can be configured to execute computer program instructions stored in the memory, causing the communication device to perform the methods described in each of the above aspects. Optionally, the communication device also includes a communication interface, with the processor coupled to the communication interface. When the communication device is a network device, the communication interface may be a transceiver or an input / output interface; when the communication device is a chip included in the network device, the communication interface may be the chip's input / output interface. Optionally, the transceiver may be a transceiver circuit, and the input / output interface may be an input / output circuit.

[0028] In a fourth aspect, an embodiment of the present application provides a chip system, comprising: a processor, the processor being coupled to a memory, the memory being used to store programs or instructions, and when the programs or instructions are executed by the processor, the chip system implements the methods in the above aspects.

[0029] Optionally, the chip system further includes an interface circuit for interacting code instructions with the processor.

[0030] Optionally, there may be one or more processors in the chip system, and the processor may be implemented in hardware or software. When implemented in hardware, the processor may be a logic circuit, an integrated circuit, etc. When implemented in software, the processor may be a general-purpose processor implemented by reading software code stored in a memory.

[0031] Optionally, the chip system may include one or more memories. The memory may be integrated with the processor or provided separately from the processor. For example, the memory may be a non-transient processor, such as a read-only memory (ROM), which may be integrated with the processor on the same chip or provided on separate chips.

[0032] In a fifth aspect, an embodiment of the present application provides a computer-readable storage medium having a computer program or instruction stored thereon. When the computer program or instruction is executed, the communication device executes the method in any possible design of the above aspects or aspects.

[0033] In a sixth aspect, an embodiment of the present application provides a computer program product, which, when executed by a communication device, enables the communication device to execute the method in the above aspects or any possible design of the aspects.

[0034] In a seventh aspect, embodiments of the present application provide a communications system comprising a session management function network element and an intermediate session management function network element. Optionally, the communications system may further comprise one or more of an anchor user plane function network element, an intermediate user plane function network element, a multicast / broadcast session management function network element, and a multicast / broadcast user plane function network element. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 A schematic diagram of a network architecture of a communication system applicable to embodiments of the present application;

[0036] Figure 2 A schematic diagram of a network architecture of a communication system supporting multicast / broadcast services applicable to an embodiment of the present application;

[0037] Figure 3 Schematic diagram of two data transmission modes for multicast / broadcast services in 5G networks;

[0038] Figure 4 A flowchart of a multicast / broadcast session management method provided in an embodiment of the present application;

[0039] Figure 5 This is a schematic diagram of the effect of path optimization for the first multicast / broadcast service in the scenario of inserting the I-SMF in an embodiment of the present application;

[0040] Figure 6 A possible implementation method of a multicast / broadcast session management method provided in an embodiment of the present application in a scenario where an I-SMF is replaced;

[0041] Figure 7 This is a schematic diagram of the effect of performing path optimization on the first multicast / broadcast service in the scenario of replacing the I-SMF in an embodiment of the present application;

[0042] Figure 8 Another possible implementation of a multicast / broadcast session management method provided in an embodiment of the present application in a scenario where an I-SMF is replaced;

[0043] Figure 9This is a flow chart of Example 1 in the embodiment of the present application;

[0044] Figure 10 This is a flow chart of Example 2 in the embodiment of this application;

[0045] Figure 11 This is a flow chart of Example 3 in the embodiments of this application;

[0046] Figure 12 This is a flow chart of Example 4 in the embodiments of the present application;

[0047] Figure 13 and Figure 14 A schematic structural diagram of a communication device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the embodiments of the present application will be further described in detail below with reference to the accompanying drawings.

[0049] Please refer to Figure 1 , a network architecture of a communication system to which the embodiment of the present application is applicable. Figure 1 As shown, the communication system includes three parts: terminal equipment, data network (DN) and operator network.

[0050] The operator network may include, but is not limited to, one or more of the following network elements or functional entities: an access and mobility management function (AMF) network element, a session management function (SMF) network element, a user plane function (UPF) network element, a unified data management (UDM) network element, a policy control function (PCF) network element, an authentication server function (AUSF) network element, a network slice selection function (NSSF) network element, an application function (AF) network element, and a radio access network (RAN) device. Optionally, the operator network may also include some network elements not shown, such as a network function repository function (NRF) network element, a unified data repository (UDR) network element, or a network exposure function (NEF) network element.

[0051] In a specific implementation, a terminal device is a device for implementing wireless communication functions, and may also be referred to as a terminal, user equipment (UE), mobile station, mobile terminal, etc. In this application, a terminal device may be a user equipment (UE), an access terminal, a terminal unit, a terminal station, a mobile station, a mobile station, a remote station, a remote terminal, a mobile device, a wireless communication device, a terminal agent, or a terminal device in a 5G network or a future evolved public land mobile network (PLMN). The access terminal may be a cellular phone, a cordless phone, a session initiation protocol (SIP) phone, a wireless local loop (WLL) station, a personal digital assistant (PDA), a handheld device with wireless communication capabilities, a computing device or other processing device connected to a wireless modem, a vehicle-mounted device or a wearable device, a virtual reality (VR) terminal device, an augmented reality (AR) terminal device, a wireless terminal in industrial control, a wireless terminal in self-driving, a wireless terminal in remote medical, a wireless terminal in smart grid, a wireless terminal in transportation safety, a wireless terminal in smart city, a wireless terminal in smart home, etc. This application does not limit the specific technology and specific device form adopted by the terminal device. The terminal device may be mobile or fixed, and there is no limitation.

[0052] The above-mentioned terminal device can establish a connection with the operator network through the interface provided by the operator network (such as the N1 interface, etc.), and use the data and / or voice services provided by the operator network. The terminal device can also access the DN through the operator network and use the operator services deployed on the DN and / or services provided by a third party. Among them, the above-mentioned third party may be a service provider other than the operator network and the terminal device, and may provide other data and / or voice services to the terminal device. Among them, the specific form of the above-mentioned third party can be determined according to the actual application scenario and is not limited here.

[0053] The radio access network (RAN) is a subnetwork of the operator's network, serving as the implementation system between service nodes and terminal devices within the operator's network. To access the operator's network, a terminal device must first pass through the RAN, which then connects to the operator's network's service nodes.

[0054] Access network equipment is a device that provides wireless communication functions for terminal equipment, also known as RAN equipment (node). In this application, the access network equipment can be the next generation base station (g nodeB, gNB), evolved node B (evolved node B, eNB), radio network controller (radio network controller, RNC), node B (nodeB, NB), base station controller (base station controller, BSC), base transceiver station (base transceiver station, BTS), home base station (for example, home evolved nodeB, or home node B, HNB), baseband unit (baseBand unit, BBU), transmission point (transmitting and receiving point, TRP), transmission point (transmitting point, TP), mobile switching center, etc. The access network equipment can also be a module or unit that completes part of the functions of the base station, such as a centralized unit (CU) or a distributed unit (DU). This application does not limit the specific technology and specific equipment form adopted by the RAN equipment.

[0055] The AMF network element is responsible for access and mobility management functions. It can receive non-access stratum (NAS) signaling of terminal devices (for example, including mobility management (MM) signaling and session management (SM) signaling) and related signaling of access network devices (for example, including base station granularity N2 signaling that interacts with AMF network elements), complete the user registration process and forwarding of SM signaling and mobility management.

[0056] The SMF network element is responsible for session management functions and completes the processes related to the establishment, release, and update of protocol data unit (PDU) sessions.

[0057] The UPF network element is responsible for user-plane service processing, such as data packet routing and transmission, packet inspection, service usage reporting, quality of service (QoS) processing, lawful interception, uplink packet inspection, and downlink packet storage.

[0058] PDU session anchor UPF (PSA UPF), also known as PDU session anchor, serves as the anchor point connected to the PDU session and is responsible for filtering, forwarding, rate control, and billing of user plane data of the terminal device.

[0059] The intermediate UPF (I-UPF) network element, also known as the forwarding UPF network element, can be used to forward user plane data between the access network device and the PSA UPF or between the I-UPF and the PSA-UPF.

[0060] The PCF network element is responsible for user policy management, including both mobility-related policies and PDU session-related policies, such as quality of service (QoS) policies and billing policies.

[0061] The UDM network element is responsible for managing contract data, user access authorization, and other functions.

[0062] The UDR network element is responsible for the storage and access of contract data, policy data, application data and other types of data.

[0063] The AUSF network element is responsible for authenticating and authorizing the access of terminal devices.

[0064] The AF network element is responsible for communicating application-side requirements to the network, such as QoS requirements or user status event subscriptions. The AF can be a third-party functional entity or an application service deployed by the operator. The AF network element can also be called an application server or a third-party device.

[0065] Data networks are used to provide users with business services, such as operator services, internet access services, and third-party services. Data networks can be private networks, such as local area networks (LANs), external networks not controlled by the operator, such as the Internet, or proprietary networks jointly deployed by operators, such as those configured for IP multimedia core network subsystem (IMS) services.

[0066] like Figure 1As shown, the terminal device can access the communication system through the access network device. The terminal device can communicate with the AMF network element through a Next generation (NG) 1 interface (referred to as N1), the access network device communicates with the AMF network element through an N2 interface (referred to as N2), the access network device communicates with the UPF network element through an N3 interface (referred to as N3), the AMF network element communicates with the SMF network element through an N11 interface (referred to as N11), the AMF network element communicates with the UDM network element through an N8 interface (referred to as N8), the AMF network element communicates with the AUSF network element through an N12 interface (referred to as N12), the AMF network element communicates with the PCF network element through an N15 interface (referred to as N15), the SMF network element communicates with the PCF network element through an N7 interface (referred to as N7), the SMF network element communicates with the UPF network element through an N4 interface (referred to as N4), the NEF network element communicates with the SMF network element through an N29 interface (referred to as N29), and the UPF network element accesses a data network (DN) through an N6 interface (referred to as N6).

[0067] It should be noted that the forms and quantities of the network elements shown in the above Figure 1 are only for example and do not constitute a limitation on the present application. Figure 1 The network architecture involved may also include other network elements, which are not specifically limited. In addition, Figure 1 the names of the interfaces of each network element and between each network element in the above

[0068] For reference Figure 2 , a network architecture supporting multicast / broadcast services is provided in the present application. The network architecture is extended on the basis of the network architecture shown in the above Figure 1 , and adds network elements or function entities such as a multicast broadcast session management function (MB-SMF) network element and a multicast broadcast user plane function (MB-UPF) network element, which are used to support multicast / broadcast services.

[0069] Among them, MB-SMF can implement the control plane function of multicast / broadcast services and be responsible for the management of multicast / broadcast services / groups / sessions. From the control plane, MB-SMF can be connected to NEF and / or multicast / broadcast service function (MBSF), for example, to receive relevant information of multicast / broadcast services (for example, description information of multicast / broadcast services). In addition, MB-SMF can also be connected to PCF, for example, to extract policy and charging control (PCC) rules related to multicast / broadcast services. From the user plane, MB-UPF can be connected to multicast / broadcast service transport function (MBSTF) and / or AF / AS to receive service data of multicast / broadcast services. It should be noted that MB-SMF and SMF can be co-located or deployed separately, and MB-UPF and UPF can be co-located or deployed separately, and this application does not limit this.

[0070] It should be noted that the above-mentioned name of MB-SMF or MB-UPF is an example. In the 5G network, MB-SMF or MB-UPF may also be other names, which is not limited in this application.

[0071] For ease of explanation, this application will be described below using the SMF as the session management function network element and the UPF as the user plane function network element. That is, the SMF described below can be replaced with a session management function network element, and the UPF can be replaced with a user plane function network element. Furthermore, to adapt to the evolution of communication systems, the aforementioned functional network elements can be replaced with devices having the same or similar functions, without limitation.

[0072] The following is an introduction to the relevant technical features involved in the embodiments of this application.

[0073] 1. Multicast / Broadcast

[0074] Multicast / broadcast refers to multicast or broadcast, which can be understood as "point to multi-point" (PTM) communication. At the service level, multicast / broadcast service refers to the data of the service being sent to multiple terminal devices. At the core network service level, multicast / broadcast service refers to the service data of the multicast / broadcast service being sent to the terminal device through a multicast / broadcast session. Between network elements, multicast refers to the multicast tunnel between the source network element and the target network element (that is, the IP address of the target network element is the multicast IP address). For the air interface, the air interface multicast / broadcast mode refers to a piece of service data sent by the access network device, which can be received by multiple terminal devices simultaneously and / or on the same frequency. The embodiments of the present application can be applied to both multicast service transmission and broadcast service transmission.

[0075] 2. Multicast / broadcast service data transmission mode

[0076] In the case that the access network device does not support multicast / broadcast, the access network device and UPF can transmit multicast / broadcast service data in the 5G core network individual multicast / broadcast service traffic delivery (5GC individual MBS traffic delivery). In the case that the access network device supports multicast / broadcast, the access network device and UPF can transmit multicast / broadcast service data in the 5G core network shared multicast / broadcast service traffic delivery (5GC shared MBS traffic delivery).

[0077] For example, Figure 3 As shown in the figure, in the 5G core network shared multicast / broadcast service traffic transmission mode, multicast / broadcast service data reaches the RAN directly through the MB-UPF and the N3mb tunnel between the MB-UPF and the RAN. The RAN can send it to one or more UEs participating in the multicast session in a point-to-point (PTP) or point-to-multipoint (PTM) manner. In the 5G core network independent multicast / broadcast service traffic transmission mode, multicast / broadcast service data passes through the MB-UPF to the UPF, and then reaches the RAN through the N3 tunnel between the UPF and the RAN (such as the UE's PDU session). The RAN sends it point-to-point to the UE.

[0078] The multicast / broadcast capability information of the access network device can be used to indicate whether the access network device supports multicast / broadcast (i.e., to indicate whether the access network device has the ability to process multicast / broadcast). Access network devices that support multicast / broadcast can identify and process information related to multicast / broadcast services, and access network devices that do not support multicast / broadcast functions cannot identify and process information related to multicast / broadcast services.

[0079] Access network device supporting multicast / broadcast can refer to: the access network device supports transmitting multicast / broadcast service data in a 5G core network shared multicast / broadcast service traffic transmission manner, supports enhanced signaling face interaction with core network control plane network elements for multicast / broadcast services, supports receiving multicast / broadcast service data from core network user plane function network elements, supports local processing of multicast / broadcast service data, supports air interface transmission of multicast / broadcast service data through point-to-multipoint, and supports configuration of terminal receiving multicast / broadcast service data.

[0080] Access network device not supporting multicast / broadcast can refer to: the access network device does not support transmitting multicast / broadcast service data in a 5G core network shared multicast / broadcast service traffic transmission manner, but only supports 5G core network alone multicast / broadcast service traffic transmission manner to transmit multicast / broadcast service data, and multicast / broadcast service data is sent to terminal equipment through the associated PDU session of the terminal equipment joining the multicast / broadcast session.

[0081] It should be understood that after the multicast / broadcast service data reaches the access network device (for example, RAN), it is processed by the service data adaptation protocol (SDAP) layer, packet data convergence protocol (PDCP) layer, radio link control (RLC) layer, media access control (MAC) layer, and physical (PHY) layer of the access network device, and is sent to each UE receiving multicast / broadcast service data.

[0082] 3. Association relationship between PDU session and multicast / broadcast service

[0083] One terminal device can have one or more PDU sessions, and each PDU session can be associated with one or more multicast / broadcast services, that is, the terminal device can join one or more multicast / broadcast services through one PDU session. It should be noted that multicast / broadcast service is a service level / granularity, and one multicast / broadcast service can correspond to multiple terminal devices, and multiple terminal devices can also join the same multicast / broadcast service at the same time.

[0084] The PDU session is associated with the multicast / broadcast service, which can be understood as the session management context of the PDU session being associated with the multicast / broadcast service. For example, the PDU session can be associated with the multicast service by storing the identification information of the multicast / broadcast service in the session management context in the PDU session; or, it can also be understood as the multicast-broadcast session context being associated with the terminal device. For example, the PDU session can be associated with the multicast service by storing the identification information of the terminal device in the multicast / broadcast session context.

[0085] The terminal device joins the multicast / broadcast service through the PDU session, which may refer to joining the multicast / broadcast service through the user plane of the PDU session (for example, through Internet Group Management Protocol (IGMP) joining signaling), or joining the multicast / broadcast service through the control plane of the PDU session (for example, through NAS signaling), which is not limited in this application.

[0086] In addition, the terminal device can also actively withdraw from one or more multicast / broadcast services associated with the PDU session. After the terminal device withdraws from a multicast / broadcast service associated with the PDU session, it means that the PDU session is also disassociated from the multicast / broadcast service.

[0087] It should be noted that the terms "system" and "network" in the embodiments of the present application can be used interchangeably. "Multiple" refers to two or more. In view of this, "multiple" can also be understood as "at least two" in the embodiments of the present application. "At least one" can be understood as one or more, for example, one, two or more. For example, including at least one means including one, two or more, and there is no restriction on which ones are included. For example, including at least one of A, B and C, then the included ones may be A, B, C, A and B, A and C, B and C, or A and B and C. Similarly, the understanding of descriptions such as "at least one" is similar. "And / or" describes the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / ", unless otherwise specified, generally indicates that the related objects before and after are in an "or" relationship.

[0088] Unless otherwise specified, the ordinal numbers such as "first" and "second" mentioned in the embodiments of the present application are used to distinguish multiple objects, and are not used to limit the order, timing, priority or importance of multiple objects, and the descriptions of "first" and "second" do not limit the objects to be different.

[0089] Please refer to Figure 4, a multicast / broadcast session management method provided in an embodiment of the present application, the method comprising:

[0090] Step 401: SMF sends first information to I-SMF.

[0091] Correspondingly, the I-SMF receives the first information from the SMF.

[0092] Among them, the SMF can be used to control the PSAUPF of the PDU session associated with the terminal device and the first multicast / broadcast service.

[0093] It should be pointed out that the embodiments of the present application are applicable to scenarios where the terminal device moves. Specifically, as the terminal device moves, when the terminal device moves out of the service area of ​​the SMF, that is, the target access network device to which the terminal device moves cannot be covered by the service areas of all UPFs controlled by the SMF, that is, the target access network device cannot be connected to any of the UPFs controlled by the SMF, an I-SMF can be inserted, and the I-SMF is responsible for forwarding control plane signaling between the target access network device and the SMF. The I-SMF can be further inserted with an I-UPF, which is responsible for forwarding user plane data between the target access network device and the PSA UPF or MB-UPF. In this application, the service area of ​​a UPF refers to a list of cells (i.e., cell list) and / or a list of tracking area identifiers (i.e., TAI list) to which this UPF can connect, and the service area of ​​an SMF refers to the union of the service areas of all UPFs controlled by the SMF.

[0094] SMF can be used to control PSA UPF, which is the anchor UPF of the associated PDU session of the terminal device. For example, the PSA UPF is the UPF to which the source access network device is connected after the terminal device establishes a PDU session through the source access network device, that is, the source access network device is in the service area of ​​the PSA UPF, and the source access network device can be connected to the PSA UPF. In the present application, the connection between the source access network device and the PSA UPF can be understood as that an N3 tunnel or a general packet radio service tunneling protocol-user plane (GTP-U) tunnel can be established between the two for data transmission. I-SMF is used to control I-UPF. For example, the I-UPF is the UPF connected to the target access network device to which the terminal device moves, that is, the target access network device is in the service area of ​​the I-UPF, and the target access network device can be connected to the I-UPF. In the present application, the connection between the target access network device and the I-UPF can be understood as that an N3 tunnel or a GTP-U tunnel can be established between the two for data transmission. In this application, the source access network device may refer to the access network device that establishes a PDU session for the terminal device through the access network device; the target access network device may refer to the access network device after the terminal device is switched due to mobility.

[0095] In the embodiment of the present application, the SMF controlling the PSA UPF may mean that the SMF and the PSA UPF may interact through an N4 session message or a packet forwarding control protocol (PFCP) session message. Similarly, the I-SMF controlling the I-UPF may mean that the I-SMF and the I-UPF may interact through an N4 session message or a PFCP session message. The N4 session message may, for example, be an N4 session modification request / response, an N4 session establishment request / response, or an N4 session release request / response. The PFCP session message may, for example, be a PFCP session modification request / response, a PFCP session establishment request / response, or a PFCP session release request / response.

[0096] The embodiments of the present application also involve network elements related to multicast / broadcast services, such as MB-SMF1, MB-UPF1, MB-SMF2, and MB-UPF2. Among them, MB-SMF1 can be used to control MB-UPF1. MB-SMF1 refers to the MB-SMF that implements the control plane function of the first multicast / broadcast service in the first service area of ​​the first multicast / broadcast service where the source access network device is located, and is responsible for managing the first multicast / broadcast service / group / session; correspondingly, MB-UPF refers to the MB-UPF that implements the user plane function of the first multicast / broadcast service in the first service area of ​​the first multicast / broadcast service where the source access network device is located, and is responsible for transmitting data of the first multicast / broadcast service.

[0097] MB-SMF2 is used to control MB-UPF2. MB-SMF2 refers to the control plane function of the first multicast / broadcast service implemented in the second service area of ​​the first multicast / broadcast service where the target access network device is located, and is responsible for managing the first multicast / broadcast service / group / session. Correspondingly, MB-UPF2 refers to the user plane function of the first multicast / broadcast service implemented in the second service area of ​​the first multicast / broadcast service where the target access network device is located, and is responsible for transmitting data of the first multicast / broadcast service.

[0098] It should be noted that MB-SMF1 and MB-SMF2 may be the same or different MB-SMFs, and similarly, MB-UPF1 and MB-UPF2 may also be the same or different MB-UPFs, which is not limited in this application.

[0099] The first information may include information about the first multicast / broadcast service. The information about the first multicast / broadcast service may include one or more of the following information: identification information of the first multicast / broadcast service, identification information of an area session of the first multicast / broadcast service (such as an area session ID), multicast / broadcast quality of service (QoS) information of the first multicast / broadcast service, and unicast QoS information corresponding to the multicast / broadcast QoS information of the first multicast / broadcast service.

[0100] The identification information of the multicast / broadcast service can include one or more of the following: context information of the multicast / broadcast session (MBS session context), IP multicast address corresponding to the multicast / broadcast service, identification information of a PDU session associated with the multicast / broadcast session (such as a PDU session ID), service data flow (SDF) identification rule of the multicast / broadcast service, packet filter information of data of the multicast / broadcast service, identification information of a multicast / broadcast group corresponding to the multicast / broadcast service (such as a temporary mobile group identifier (TMGI) of the multicast / broadcast group), a multicast / broadcast service session ID (MBS session ID), an internet protocol (IP) address of an application server (such as an AF) providing data of the multicast / broadcast service, a service identifier (service ID) of the multicast / broadcast service, a source-specific IP multicast address, and a packet detection rule (PDR) of the multicast / broadcast service. It should be understood that the PDR is a set of filters, each filter is a five-tuple, and each filter includes a source address, a destination address, a source port number, a destination port number, and a protocol number of the multicast service. The PDR is used to filter data of the multicast service.

[0101] The area session refers to different area sessions corresponding to different areas of the same multicast / broadcast service, which are used to distribute different content. That is, the same multicast / broadcast service has the same identification information of the multicast / broadcast service (such as an MBS session ID) and different identification information of the area session (such as an area session ID) in different areas. For example, a nationwide weather forecast is a multicast / broadcast service, which distributes different weather forecast content in different areas.

[0102] Optionally, the first information also includes first indication information, which is used to trigger the I-SMF to establish a first tunnel between the I-UPF and MB-UPF2 for transmitting data of the first multicast / broadcast service, or the first indication information is used to query the I-SMF whether the above-mentioned first tunnel has been established, or the first indication information is used to trigger the I-SMF to perform path optimization for the first multicast / broadcast service. The first indication information can also be called a tunnel establishment indication, a tunnel query indication, or a path optimization indication. It should be noted that the above-mentioned first tunnel refers to a directly connected (directly connect or direct connection) tunnel between the I-UPF and MB-UPF2. That is, the I-UPF and MB-UPF do not pass through other network element nodes. When the data of the multicast / broadcast service is transmitted through the first tunnel, the data of the multicast / broadcast service does not need to be forwarded by other network element nodes (such as UPF).

[0103] Exemplarily, the above-mentioned first information can be carried in messages or signaling such as PDU session context update request / response message (Nsmf_PDUSession_UpdateSMContext Request / Response), PDU session update request / response message (Nsmf_PDUSession_Update Request / Response), or PDU session context request / response message (Nsmf_PDUSession_Context Request / Response), or can also be carried in other newly introduced messages or signaling during the mobility process of the terminal device and sent, which is not limited in this application.

[0104] Step 402: The I-SMF sends second information to the SMF.

[0105] Correspondingly, the SMF receives the second information from the I-SMF.

[0106] The I-SMF is used to control the I-UPF.

[0107] The second information may be used to indicate that a first tunnel has been established, where the first tunnel is a tunnel for transmitting first multicast / broadcast service data between the I-UPF and the MB-UPF2.

[0108] Optionally, the second information may further include information about the first multicast / broadcast service.

[0109] In addition, the second information can also be used to indicate support for path optimization for the first multicast / broadcast service, or to indicate that path optimization for the first multicast / broadcast service has been completed, or to indicate that the transmission path of the data of the first multicast / broadcast service does not pass through the PSA UPF, or to indicate that the I-SMF supports multicast / broadcast.

[0110] It should be noted that the above-mentioned indication function of the second message can be reflected in various ways. For example, the above-mentioned content can be implicitly indicated by the second message carrying the above-mentioned first multicast / broadcast service information. Alternatively, the above-mentioned content can be explicitly indicated by carrying a dedicated indication information or notification information in the second message.

[0111] Exemplarily, the second information can be carried in messages or signaling such as the PDU session update request / response message (Nsmf_PDUSession_Update Request / Response), the PDU session creation request / response message (Nsmf_PDUSession_CreateRequest / Response), or the PDU session context update request / response message (Nsmf_PDUSession_UpdateSMContext Request / Response), or can also be carried in other newly introduced messages or signaling during the mobility process of the terminal device, which is not limited in this application.

[0112] In an embodiment of the present application, after receiving the first information, if the I-SMF supports multicast / broadcast (i.e., has the relevant processing capabilities for multicast / broadcast), the I-SMF may query whether the first tunnel has been established based on the information of the first multicast / broadcast service carried in the first information and / or the first indication information. If not established, the I-SMF establishes the first tunnel to optimize the transmission path of the data of the first multicast / broadcast service. Furthermore, the I-SMF may send a second message to the SMF to notify the SMF that the first tunnel has been established, or supports path optimization for the first multicast / broadcast service, or the path optimization for the first multicast / broadcast service has been completed. Through the above process, the SMF can know that the I-SMF has the processing capabilities for multicast / broadcast services, and can optimize the transmission path of the first multicast / broadcast service.

[0113] Exemplarily, the I-SMF establishing the first tunnel may include: the I-SMF establishing the first tunnel through interaction with the MB-SMF. Specifically, it may include:

[0114] When the first tunnel adopts unicast transmission mode, the I-SMF requests the I-UPF to allocate the first tunnel information through the N4 session modification request or the N4 session establishment request or the PFCP session modification request or the PFCP session establishment request, and the I-UPF sends the allocated first tunnel information to the I-SMF through the N4 session modification response or the N4 session establishment response or the PFCP session modification response or the PFCP session establishment response. The first tunnel information may include the tunnel endpoint identifier (TEID) of the first tunnel and / or the IP address of the I-UPF. Afterwards, the I-SMF sends the first tunnel information to the MB-SMF through control plane signaling. The control plane signaling may be, for example: group / broadcast service data reception request, Nmbsmf_Reception_Request request; multicast / broadcast session context update request, Nmbsmf_MBSSession_ContextUpdate request; multicast broadcast context status subscription, Nmbsmf_MBSSession_ContextStatusSubscribe; multicast / broadcast session creation request, Nmbsmf_MBSession_Create request; multicast / broadcast session update request, Nmbsmf_MBSSession_Updaterequest; multicast / broadcast session status subscription, Nmbsmf_MBSSession_StatusSubscribe. The MB-SMF further sends the first tunnel information to the MB-UPF through an N4mb session modification request (N4mb session modification request) or an N4mb session establishment request (N4mb session establishment request), so that the MB-UPF can send the data of the first multicast / broadcast service to the I-UPF.

[0115] When the first tunnel adopts the multicast transmission mode, the I-SMF sends a request for receiving multicast / broadcast service data to the MB-SMF through control plane signaling, where the control plane signaling may be, for example, a multicast / broadcast service data reception request, Nmbsmf_Reception_Request request; a multicast / broadcast session context update request, Nmbsmf_MBSSession_ContextUpdate request; a multicast broadcast context status subscription, Nmbsmf_MBSSession_ContextStatusSubscribe; a multicast / broadcast session creation request, Nmbsmf_MBSession_Create request; a multicast / broadcast session update request, Nmbsmf_MBSSession_Update request; and a multicast / broadcast session status subscription, Nmbsmf_MBSSession_StatusSubscribe. Further, the MB-SMF sends first tunnel information to the I-SMF through a multicast / broadcast service data reception response, where the first tunnel information may include a TEID of the first tunnel and / or an IP address of the MB-UPF, and the multicast / broadcast service data reception response may be, for example, a Nmbsmf_Reception_Request response; a Nmbsmf_MBSSession_ContextUpdate response; a Nmbsmf_MBSSession_ContextStatusNotify; a Nmbsmf_MBSession_Create response; a Nmbsmf_MBSSession_Update response; and a Nmbsmf_MBSSession_StatusNotify. After receiving the first tunnel information, the I-SMF sends the allocated first tunnel information to the I-UPF through an N4 session modification request or an N4 session establishment request or a PFCP session modification request or a PFCP session establishment request, so that the I-UPF can receive the data of the first multicast / broadcast service sent by the MB-UPF.

[0116] The effect of path optimization on the first multicast / broadcast service can be as follows Figure 5As shown. Before optimization, the transmission path of the data of the first multicast / broadcast service is: MB-UPF2–>PSA UPF–>I-UPF–>target access network device. After optimization, the transmission path of the data of the first multicast / broadcast service is: MB-UPF2–>I-UPF–>target access network device. It can be seen that after optimization, the transmission path of the data of the first multicast / broadcast service saves two hops of transmission paths from MB-UPF2 to PSA UPF and from PSA UPF to I-UPF. It can be understood that multicast / broadcast services usually refer to data transmission in the downlink direction. Therefore, the above optimization process is described by taking the path optimization in the downlink direction as an example. If there is a multicast / broadcast service in the uplink direction, the optimization process is similar to that of the downlink direction and will not be repeated.

[0117] Furthermore, if Figure 4 As shown in optional step 403 in , after the SMF receives the second information from the I-SMF, the SMF may also send a first message to the PSA UPF based on the second information, and the first message is used to trigger the PSA UPF to release the resources used to transmit the first multicast / broadcast service data. The "release" can also be understood as meanings such as removal or deactivation. The "resources" may include PDRs, forwarding action rules (FAR), QoS enforcement rules (QER), etc. set by the PSA UPF for transmitting the data of the first multicast / broadcast service. The first message may be an N4 session modification request message, or an N4 session establishment request message, or a PFCP session modification request message, or a PFCP session establishment request message.

[0118] Similar, such as Figure 4Optionally, as shown in optional step 404, after determining that the first tunnel has been established, the I-SMF can further send a second message to the I-UPF, the second message being used to trigger the I-UPF to configure resources for transmitting data of the first multicast / broadcast service. The "configuration" can also be understood as adding or activating, etc. The resources can include PDR, FAR, QER, etc. corresponding to the transmission of data of the first multicast / broadcast service, as described above. The second message can be an N4 session modification request message, or an N4 session establishment request, or a PFCP session modification request message, or a PFCP session establishment request message.

[0119] It should be noted that step 404 is performed after step 401, but the present application does not specifically limit the order of execution between step 404 and steps 402 and 403.

[0120] Optionally, as Figure 4 Optionally, as shown in optional step 400, before the SMF sends the first information to the I-SMF, the I-SMF can send its multicast / broadcast capability information to the SMF, the multicast / broadcast capability information being used to indicate whether the I-SMF supports multicast / broadcast (i.e. whether it supports processing of multicast / broadcast, or whether it has the function of processing multicast / broadcast). After the SMF receives the multicast / broadcast capability information of the I-SMF, if it is determined according to the multicast / broadcast capability information that the I-SMF supports multicast / broadcast, the SMF can send the first information to the I-SMF.

[0121] The above technical solution, when the terminal device moves to the service area of the I-UPF controlled by the I-SMF, the SMF can send the information of the first multicast / broadcast service and / or the first indication information to the I-SMF to trigger the I-SMF to establish the first tunnel between the I-UPF and the MB-UPF for transmitting data of the first multicast / broadcast service, thereby facilitating the optimization of the transmission path of the first multicast / broadcast service using the first tunnel. In this way, the data of the first multicast / broadcast service can no longer be forwarded through the PSA UPF, thereby reducing the transmission delay of the multicast / broadcast service data and saving network transmission resources.

[0122] The above technical solution of the present application can be applied to the scenarios of inserting I-SMF and replacing I-SMF. Among them, the scenario of replacing I-SMF means that as the terminal device continues to move, when the terminal device moves out of the service area of ​​the source I-SMF (that is, when the target access network device to which the terminal device has recently moved cannot be covered by the service area of ​​all UPFs controlled by SMF, nor can it be covered by the service area of ​​all UPFs controlled by the source I-SMF), the I-SMF and I-UPF can be replaced. In this way, the I-SMF before replacement can be called the source I-SMF, the I-UPF before replacement can be called the source I-UPF, the I-SMF after replacement can be called the target I-SMF, and the I-UPF after replacement can be called the target I-UPF.

[0123] In the scenario of replacing the I-SMF, one possible implementation is as follows: Figure 4 The steps performed by the SMF shown in FIG. 1 can be performed by the source I-SMF, and the steps performed by the I-SMF can be performed by the target I-SMF. The corresponding method flow can be as follows: Figure 6 As shown in step 601 to step 604, no further details will be given. It can be understood that in this embodiment, the first tunnel refers to the tunnel between the target I-UPF and MB-UPF2, and the so-called path optimization refers to the following. Figure 7 As shown in the figure, the transmission path is optimized from the previous MB-UPF2–>PSA UPF->target I-UPF–>target access network device to MB-UPF2–>target I-UPF–>target access network device. In addition, in this embodiment, both the source I-SMF and the target I-SMF support multicast / broadcast.

[0124] Another possible implementation is that if the source I-SMF does not support multicast / broadcast, the target I-SMF cannot perform Figure 6 According to the process shown in , the information of the first multicast / broadcast service is obtained from the source I-SMF. Figure 8 As shown in steps 800 to 804, the target I-SMF may first send multicast / broadcast capability information to the SMF to inform the SMF that it supports multicast / broadcast. Furthermore, the SMF may send a first message to the target I-SMF based on the capability information, which carries information about the first multicast / broadcast service and / or a first indication information to instruct the target I-SMF to perform path optimization for the first multicast / broadcast service. After the path optimization is completed, the target I-SMF may send a second message to the SMF to inform the SMF that the first tunnel has been established. Subsequently, the SMF may send a first message to the PSA UPF to trigger the PSA UPF to release resources used to transmit data for the first multicast / broadcast service, and the target I-SMF may also send a second message to the target I-UPF to trigger the target I-UPF to configure resources for the first multicast / broadcast service.

[0125] It should be noted that the technical solution of the embodiment of the present application can be applied to the handover process or service request (SR) process involved in the terminal device mobility process. The technical solution of the embodiment of the present application will be exemplarily described below in conjunction with various processes that may be involved in the terminal device mobility process.

[0126] It should be understood that the following examples are only a few of the scenarios in which the embodiments of the present application may be applied, and the present application includes but is not limited to them. In addition, the source AMF in the following examples can also be referred to as the old AMF (old AMF), and the target AMF can also be referred to as the new AMF (new AMF). Similarly, the source I-SMF can also be referred to as the old I-SMF (old I-SMF), and the target I-SMF can also be referred to as the new I-SMF (new I-SMF). The source I-UPF can also be referred to as the old I-UPF (old I-UPF), and the target I-UPF can also be referred to as the new I-UPF (new I-UPF).

[0127] Example 1: Scenario where the UE performs Xn handover and inserts the I-SMF

[0128] Step 901: The target access network device sends an N2 path switch request (N2 path switch request) to the AMF.

[0129] The N2 path switching request may include the location information of the UE and the tunnel information allocated by the target access network device.

[0130] The location information of the UE may include one or more pieces of information such as identification information of a tracking area, identification information of an access network device, or identification information of a cell. Specifically, the location information of the UE may be UE location information.

[0131] The tunnel information allocated by the target access network device may be downlink tunnel information, used to establish a tunnel from the I-UPF to the target access network device so that the I-UPF can send data to the target access network device. Specifically, the tunnel information allocated by the target access network device may be access network tunnel information AN tunnel Info.

[0132] It should be noted that step 901 may be performed after the UE completes the handover, where the UE completing the handover may mean that the UE successfully accesses the target access network device.

[0133] Step 902: AMF sends a PDU session context update request to SMF.

[0134] Specifically, the PDU session context update request may be a session management context update request, such as Nsmf_PDUSession_UpdateSMContext Request.

[0135] The PDU session context update request may include an identifier of the QoS flow for which air interface resource allocation fails (eg, QoS flow ID).

[0136] Accordingly, after receiving the PDU session context update request, the SMF may initiate a PDU session modification process to trigger deletion of the QoS flow for which air interface resource allocation fails.

[0137] Step 903: AMF selects I-SMF based on the UE's location information.

[0138] It should be noted that since the PSA PDU controlled by the SMF cannot be directly connected to the target access network device, the AMF can execute step 904 and select the I-SMF according to the UE's location information.

[0139] Specifically, the AMF can select an SMF whose service area can cover the location of the UE as the I-SMF based on the location information of the UE.

[0140] Step 904: AMF sends a PDU session context creation request to I-SMF.

[0141] Specifically, the PDU session context creation request may be Nsmf_PDUSession_CreateSMContextRequest.

[0142] The PDU session context creation request may include UE identification information (such as user permanent identifier (SUPI)), UE location information, AMF ID, SMF ID, session management context identifier (SM context ID) and tunnel information allocated by the target access network device.

[0143] Step 905: The I-SMF sends a PDU session context request to the SMF.

[0144] Specifically, the PDU session context request may be Nsmf_PDUSessionContextRequestRequest.

[0145] The PDU session context request can include a session management context type and a session management context identifier, which can be used by the I-SMF to obtain the session management context from the SMF.

[0146] At step 906, the SMF determines that the PDU session corresponding to the session management context identifier is associated with the multicast / broadcast service, and sends a PDU session context response to the I-SMF.

[0147] Specifically, the PDU session context response can be Nsmf_PDUSessionContextRequestResponse.

[0148] Exemplarily, the SMF can obtain the session management context of the PDU session requested by the I-SMF according to the session management context type and the session management context identifier. In an implementation, if the session management context includes the identification information (such as MBS session ID) of the multicast / broadcast service, the SMF can determine that the PDU session is associated with the multicast / broadcast service. In another implementation, the SMF stores the multicast / broadcast session context of the multicast / broadcast service, and if the multicast / broadcast session context includes the identification information (such as SUPI) of the UE, the SMF can determine that the PDU session is associated with the multicast / broadcast service. Further, after determining that the PDU session is associated with the multicast / broadcast service, the SMF can send a PDU session context response to the I-SMF, and the PDU session context response can include the session management context.

[0149] The PDU session context response can further include first information. For the introduction of the first information, please refer to the related description in the foregoing, which will not be described here.

[0150] Optionally, if the information of the multicast / broadcast service included in the first information only includes the identification information of the multicast / broadcast service, the I-SMF can select the MB-SMF according to the location information of the UE and the multicast / broadcast service session identifier (such as MBS session ID) through the NRF or the UDM. The I-SMF can obtain the multicast / broadcast QoS information of the multicast / broadcast service from the MB-SMF, and generate the unicast QoS information corresponding to the multicast / broadcast QoS information.

[0151] If the I-SMF supports multicast / broadcast, the following steps 908 to 918 are performed:

[0152] Step 907: The I-SMF interacts with the MB-SMF to establish a tunnel between the I-UPF and the MB-UPF for transmitting the multicast / broadcast service.

[0153] The tunnel may be, for example, the first tunnel described above.

[0154] Step 908: The I-SMF sends an N4 session establishment request (N4 session Eestablishment request) to the I-UPF.

[0155] The N4 session establishment request may include the tunnel information allocated by the target access network device. Optionally, if the tunnel information of the I-UPF is allocated by the I-UPF, the I-SMF may also request the I-UPF to allocate the tunnel information through the N4 session establishment request. The tunnel information may be the core network tunnel information CN tunnel Info.

[0156] Step 909: The I-UPF sends an N4 session establishment response (N4 session establishment response) to the I-SMF.

[0157] Optionally, if the tunnel information of the I-UPF is allocated by the I-UPF, the N4 session creation response also includes the tunnel information allocated by the I-UPF, which may be core network tunnel information CN tunnel Info. The tunnel information allocated by the I-UPF may include uplink tunnel information (e.g., UL CN tunnel Info) and downlink tunnel information (e.g., DL CN tunnel Info). The uplink tunnel information is used to establish a tunnel from the target access network device to the I-UPF so that the target access network device sends data to the I-UPF. The downlink tunnel information is used to establish a tunnel from the PSA UPF to the I-UPF so that the PSA UPF sends data to the I-UPF.

[0158] Step 910: The I-SMF sends a PDU session creation request to the SMF.

[0159] Specifically, the PDU session creation request may be Nsmf_PDUSession_Create Request.

[0160] The PDU session creation request may include UE identification information, UE location information, PDU session identification information (such as PDU session ID), downlink tunnel information allocated by the I-UPF, etc.

[0161] Optionally, if the I-SMF receives the first information sent by the SMF in step 907, the PDU session creation request further includes second information, which is used to indicate that the tunnel between the I-UPF and the MB-UPF for transmitting the multicast / broadcast service has been established. For details of the second information, refer to the description of the related description in the foregoing, which will not be described here.

[0162] In step 911, if the SMF receives the second information, the SMF sends an N4 session modification request to the PSA UPF.

[0163] The N4 session modification request can include the downlink tunnel information allocated by the I-UPF.

[0164] The SMF can also request the PSA UPF to allocate tunnel information through the N4 session modification request, and the tunnel information can be core network tunnel information CN tunnel Info. The tunnel information can be uplink tunnel information, which is used for the I-UPF to send data to the PSA UPF. The tunnel information allocated by the PSA UPF will be sent to the I-SMF through the PDU session context creation response in step 915, and then sent to the I-UPF by the I-SMF.

[0165] The N4 session modification request can be the first message mentioned in the foregoing embodiment, and the N4 session modification request is used to trigger the PSA PDU to release the resource for transmitting the data of the multicast / broadcast service. For details of the first message, refer to the description of the related description in the foregoing, which will not be described here.

[0166] In step 912, the PSA UPF sends an N4 session modification response to the SMF.

[0167] In step 913, the SMF sends a PDU session creation response to the I-SMF.

[0168] Specifically, the N4 session modification response can be Nsmf_PDUSession_Create Response.

[0169] In step 914, the I-SMF sends an N4 session modification request to the I-UPF.

[0170] The N4 session modification request can include the tunnel information allocated by the PSA UPF, which is used to establish the tunnel from the I-UPF to the PSA UPF, so that the I-UPF sends data to the PSA UPF.

[0171] Step 915, the I-UPF sends an N4 session modification response to the I-SMF.

[0172] Step 916, the I-SMF sends a PDU session context creation response to the AMF.

[0173] Specifically, the PDU session context creation response can be Nsmf_PDUSession_CreateSMContextResponse.

[0174] Optionally, the PDU session context creation response can include uplink tunnel information of the I-UPF.

[0175] Step 917, the AMF sends an N2 path switch response to the target access network device.

[0176] Specifically, the N2 path switch response can be N2 path switch request ack.

[0177] Optionally, the N2 path switch response can include uplink tunnel information allocated by the I-UPF.

[0178] Example two: scenario of UE performing N2 handover and inserting I-SMF

[0179] Step 1001, the source access network device sends a handover required to the source AMF (S-AMF).

[0180] Exemplarily, the handover required can include N2 session management information (i.e., N2 SM Information), which includes PDU session information of the UE to be handed over, and the PDU session information includes PDU session identifier and QoS information corresponding to unicast QoS flow included in the PDU session. Wherein, the QoS information of the unicast QoS flow includes QoS flow identifier (QoS flow identifier, QFI) and QoS parameter. If the PDU session of the UE to be handed over is associated with multicast / broadcast service, the PDU session information further includes information of unicast QoS flow to which the multicast / broadcast QoS flow is mapped.

[0181] The handover request may also include the UE's location information. The UE's location information may include one or more information such as a tracking area identifier, an access network device identifier, or a cell identifier. Specifically, the location information may refer to the UE's location information under the target access network device (i.e., target ID). The structure of this information element is defined in 3GPP Technical Specification (TS) 38.413.

[0182] If the N2 session management information indicates that there is no direct forwarding tunnel between the source access network device and the target access network device, it means that an indirect forwarding tunnel can be established between the source access network device and the target access network device. At this time, the N2 session management information can also include the indirect forwarding tunnel information allocated by the source access network device.

[0183] The switching requirement may also include the identifier of the QoS flow that the source access network device wishes to forward through the forwarding tunnel. If a multicast / broadcast QoS flow needs to be forwarded through the forwarding tunnel, the switching requirement may also include the QFI of the unicast QoS flow corresponding to the multicast / broadcast QoS flow.

[0184] Step 1002: The source AMF selects a target AMF (target-AMF, T-AMF) based on the UE's location information.

[0185] Among them, the target AMF is connected to the target access network device.

[0186] Specifically, the source AMF can select other AMFs whose service areas can cover the location of the UE as the target AMF based on the location information of the UE.

[0187] Step 1003: The source AMF sends a UE context creation request to the target AMF.

[0188] Specifically, the UE context creation request may be Namf_Communication_CreateUEContextRequest.

[0189] The UE context creation request may include the UE context information of the switching stored by the source AMF, and may also include the information sent by the source access network device to the source AMF in step 1001.

[0190] Step 1004: The target AMF selects an I-SMF based on the UE's location information.

[0191] It should be pointed out that since the PSA PDU controlled by the SMF (i.e., anchor SMF (anchor SMF, A-SMF)) cannot be directly connected to the target access network device (i.e., the UE's location can no longer be covered by the service area of ​​all UPFs controlled by the SMF), the target AMF can execute step 1004 and select I-SMF according to the UE's location information.

[0192] Specifically, the AMF can select an SMF whose service area can cover the location of the UE as the I-SMF based on the location information of the UE.

[0193] Step 1005: The target AMF sends a PDU session context creation request to the I-SMF.

[0194] Specifically, the PDU session context creation request may be Nsmf_PDUSession_CreateSMContextRequest.

[0195] The PDU session context creation request may include UE identification information (such as SUPI), UE location information, AMFID, SMF ID, session management context identifier, etc.

[0196] Step 1006: The I-SMF sends a PDU session context request to the SMF.

[0197] Specifically, the PDU session context request may be Nsmf_PDUSessionContext Request.

[0198] The PDU session context request may include a session management context type and a session management context identifier, and the session management context type and the session management context identifier are used by the I-SMF to obtain the session management context from the SMF.

[0199] Step 1007: SMF sends a PDU session context response to I-SMF.

[0200] Specifically, the PDU session context response may be Nsmf_PDUSessionContext Response.

[0201] Exemplarily, the SMF may determine the session management context requested by the I-SMF based on the session management context type and the session management context identifier, and then send a PDU session context response to the I-SMF, where the PDU session context response includes the session management context.

[0202] The PDU session context response may also include first information. For an introduction to the first information, please refer to the relevant description above, which will not be repeated here.

[0203] Step 1008: The I-SMF sends an N4 session establishment request (N4 session establishment request) to the I-UPF.

[0204] The N4 session establishment request is used to request the I-UPF to allocate tunnel information for use by the PSA UPF, also known as downlink tunnel information. Specifically, the tunnel information is core network tunnel information CN tunnel Info.

[0205] Step 1009: The I-UPF sends an N4 session establishment response (N4 session establishment response) to the I-SMF.

[0206] The N4 session establishment response may include tunnel information (ie, downlink tunnel information) allocated by the I-UPF. The tunnel information allocated by the I-UPF is used to establish a tunnel from the PSA UPF to the I-UPF, so that the PSA UPF can send data to the I-UPF.

[0207] Step 1010: The I-SMF sends a PDU session creation request to the SMF.

[0208] Specifically, the PDU session creation request may be Nsmf_PDUSession_Create Request.

[0209] The PDU session creation request may include tunnel information allocated by the I-UPF (ie, downlink tunnel information).

[0210] Step 1011: SMF sends an N4 session modification request to PSA UPF.

[0211] The N4 session modification request may include the tunnel information (ie, downlink tunnel information) allocated by the I-UPF. Optionally, the SMF may also request the PSA UPF to allocate tunnel information through the N4 session modification request. Specifically, the tunnel information may be core network tunnel information CN tunnel Info.

[0212] Step 1012: PSA UPF sends an N4 session modification response (N4 session modification response) to SMF.

[0213] The N4 session modification response may include tunnel information allocated by the PSA UPF, where the tunnel information allocated by the PSA UPF is used to establish a tunnel from the I-UPF to the PSA UPF, so that the I-UPF sends data to the PSA UPF.

[0214] Step 1013: SMF sends a PDU session creation response to I-SMF.

[0215] Specifically, the PDU session creation response may be Nsmf_PDUSession_Create Response.

[0216] The PDU session creation response may include tunnel information allocated by the PSA UPF.

[0217] Step 1014: The I-SMF sends an N4 session modification request (N4 session modification request) to the I-UPF.

[0218] The N4 session modification request may include the tunnel information allocated by the PSA UPF. Furthermore, the I-SMF may also request the I-UPF to allocate tunnel information, also known as uplink tunnel information, for use by the target access network device through the N4 session modification request. Specifically, the tunnel information may be CN tunnel Info.

[0219] Step 1015: The I-UPF sends an N4 session modification response (N4 session modification response) to the I-SMF.

[0220] The N4 session modification response may include tunnel information allocated by the I-UPF (ie, uplink tunnel information). The tunnel information allocated by the I-UPF is used to establish a tunnel from the target access network device to the I-UPF so that the target access network device sends data to the I-UPF.

[0221] Step 1016: The I-SMF sends a PDU session context creation response to the target AMF.

[0222] Specifically, the PDU session context creation response may be Nsmf_PDUSession_Create Response.

[0223] The PDU session context creation response may include the tunnel information allocated by the I-UPF (ie, uplink tunnel information), and may also include the N2 session management information in step 1001.

[0224] Step 1017: The target AMF sends a handover request to the target access network device.

[0225] The handover request may include the tunnel information allocated by the I-UPF (ie, uplink tunnel information) and may also include N2 session management information.

[0226] Step 1018: The target access network device sends a handover request response to the target AMF.

[0227] Specifically, the handover request response may be a handover request ACK.

[0228] The handover request response may include tunnel information allocated by the target access network device, which is used to establish a tunnel from the I-UPF to the target access network device so that the I-UPF can send data to the target access network device. Specifically, the tunnel information may be AN tunnel Info.

[0229] The handover request response may also include identification information of the unicast QoS flow for which the air interface resources are successfully created. Exemplarily, the target access network device may allocate corresponding air interface resources, such as data radio bearer (DRB) configuration information, based on the QoS information corresponding to the unicast QoS flow included in the N2 session management information. The DRB configuration information may include configuration information from the PDCP layer to the PHY layer, such as whether the PDCP layer requires encryption, whether the RLC layer adopts acknowledged mode (AM) mode or unacknowledged mode (UM) mode, the scheduling policy of the MAC layer, the modulation and coding method of the PHY layer, etc.

[0230] The handover request response may also include access configuration information, which is used by the UE to access the target access network device. For example, the access configuration information may include the cell radio network temporary identifier (C-RNTI), the radio bearer configuration information of the unicast QoS flow, and the radio bearer configuration information of the unicast QoS flow corresponding to the multicast / broadcast QoS flow. If the target access network device supports multicast / broadcast, the access configuration information may also include the radio bearer configuration information of the multicast / broadcast QoS flow.

[0231] Step 1019: The target AMF sends a PDU session context update request to the I-SMF.

[0232] Specifically, the PDU session context update request may be Nsmf_PDUSession_Update Request.

[0233] The PDU session context update request may include tunnel information allocated by the target access network device and may also include access configuration information.

[0234] Step 1020: The I-SMF sends an N4 session modification request (N4 session modification request) to the I-UPF.

[0235] The N4 session modification request may include tunnel information allocated by the target access network device.

[0236] Step 1021: The I-UPF sends an N4 session modification response (N4 session modification response) to the I-SMF.

[0237] Step 1022: The I-SMF sends a PDU session context update response to the target AMF.

[0238] Specifically, the PDU session context update response may be Nsmf_PDUSession_Update Response.

[0239] The PDU session context update response may include access configuration information.

[0240] Step 1023: The target AMF sends a UE context creation response to the source AMF.

[0241] Specifically, the UE context creation response may be Namf_Communication_CreateUEContextResponse.

[0242] The UE context creation response may include access configuration information.

[0243] Step 1024: The source AMF sends a handover command to the source access network device.

[0244] The handover command may include access configuration information.

[0245] Step 1025: The source access network device sends a handover command to the UE.

[0246] The handover command may include access configuration information.

[0247] Step 1026: The UE accesses the target access network device according to the access configuration information and receives service data from the target access network device.

[0248] The service data may be, for example, multicast / broadcast service data.

[0249] It should be noted that if the target access network device does not support multicast / broadcast, the target access network device sends the multicast / broadcast service data to the UE through the PDU session.

[0250] Step 1027: The target access network device sends a handover notify to the target AMF.

[0251] The handover notification is used to notify the target AMF that the UE has successfully switched to the target access network device.

[0252] Step 1028: The target AMF sends a PDU session context update request to the I-SMF.

[0253] The PDU session context update request is used to notify the UE of successful handover to the target access network device.

[0254] Step 1029: The I-SMF interacts with the MB-SMF to establish a first tunnel.

[0255] For the introduction of the first tunnel, please refer to the relevant description above and will not be repeated here.

[0256] Step 1030: The I-SMF sends a PDU session update request to the SMF.

[0257] Specifically, the PDU session update request may be Nsmf_PDUSession_Update Request.

[0258] The PDU session update request may include second information. For an introduction to the second information, please refer to the relevant description above, which will not be repeated here.

[0259] Step 1031: SMF sends an N4 session modification request to PSA UPF.

[0260] The N4 session modification request may be the first message mentioned in the above embodiment, which is used to trigger the PSA PDU to release resources used to transmit data of the multicast / broadcast service. For an introduction to the first message, please refer to the relevant description above and will not be repeated here.

[0261] Example 3: Scenario where the UE performs N2 handover and replaces the I-SMF

[0262] Step 1101: The source access network device sends a handover required message to the source AMF.

[0263] For the specific implementation of step 1101, please refer to the relevant description in step 1001 and will not be repeated here.

[0264] Step 1102: The source AMF selects a target AMF based on the UE's location information.

[0265] For the specific implementation of step 1102, please refer to the relevant description in step 1002 and will not be repeated here.

[0266] Step 1103: The source AMF sends a UE context creation request to the target AMF.

[0267] Specifically, the UE context creation request may be Namf_Communication_CreateUEContextRequest.

[0268] The UE context creation request may include the UE context information of the handover stored by the source AMF, and may also include the information sent by the source access network device to the source AMF in step 1101.

[0269] Step 1104: The target AMF selects a target I-SMF based on the UE's location information.

[0270] It should be pointed out that since the PSA PDU controlled by the SMF (i.e., A-SMF) cannot be directly connected to the target access network device (it can be understood that the UE is located outside the service area of ​​all UPFs controlled by the SMF), the target AMF can execute step 1104 and select the target I-SMF.

[0271] Specifically, the target AMF can select an SMF whose service area can cover the location of the UE as the target I-SMF based on the location information of the UE.

[0272] Step 1105: The target AMF sends a PDU session context creation request to the target I-SMF.

[0273] Specifically, the PDU session context creation request may be Nsmf_PDUSession_CreateSMContextRequest.

[0274] The PDU session context creation request may include UE identification information (such as SUPI), UE location information, AMFID, SMF ID, session management context identifier, etc.

[0275] Step 1106: The target I-SMF sends a PDU session context request to the source I-SMF.

[0276] Specifically, the PDU session context request may be Nsmf_PDUSessionContext Request.

[0277] It should be noted that if the source I-SMF does not support multicast / broadcast, then continue to execute steps 1107 to 1127.

[0278] Step 1107: The source I-SMF sends a PDU session context response to the target I-SMF.

[0279] Specifically, the PDU session context response may be Nsmf_PDUSessionContext Response.

[0280] It should be noted that, since the source I-SMF does not support multicast / broadcast, the PDU session context response does not include the first information. For an introduction to the first information, please refer to the relevant description above and will not be repeated here.

[0281] Step 1108: The target I-SMF sends an N4 session establishment request (N4 session establishment request) to the target I-UPF.

[0282] The N4 session establishment request is used to request the target I-UPF to allocate tunnel information. Specifically, the tunnel information may be core network tunnel information CN tunnel Info.

[0283] Step 1109: The target I-UPF sends an N4 session establishment response (N4 session establishment response) to the target I-SMF.

[0284] The N4 session establishment response includes tunnel information allocated by the target I-UPF. The tunnel information allocated by the target I-UPF may include uplink tunnel information and downlink tunnel information. The uplink tunnel information is used to establish a tunnel from the target access network device to the I-UPF, allowing the target access network device to send data to the I-UPF. The downlink tunnel information is used to establish a tunnel from the PSA UPF to the I-UPF, allowing the PSA UPF to send data to the I-UPF.

[0285] Step 1110: The target I-SMF sends multicast / broadcast capability information to the SMF.

[0286] The multicast / broadcast capability information is used to indicate that the target I-SMF supports multicast / broadcast. The multicast / broadcast capability information can be carried in an N16 message or an N16a message, or carried in other new messages, which is not limited in this application.

[0287] It should be noted that step 1110 can be performed after step 1107 or step 1108 or step 1109, and this application does not make any specific limitation.

[0288] Step 1111: The SMF determines that the PDU session is associated with the multicast / broadcast service and sends first information to the target I-SMF.

[0289] For the introduction of the first information, please refer to the relevant description above and I will not repeat it here.

[0290] The first information can be carried in an N16 message or an N16a message and sent, or carried in other new messages and sent, which is not limited in this application.

[0291] Step 1112: The target I-SMF sends a PDU session context creation response to the target AMF.

[0292] Specifically, the PDU session context creation response may be Nsmf_PDUSession_Create Response.

[0293] The PDU session context creation response may include the tunnel information allocated by the I-UPF and the N2 session management information in step 1101.

[0294] Step 1113: The target AMF sends a handover request to the target access network device.

[0295] The handover request may include tunnel information allocated by the I-UPF and may also include N2 session management information.

[0296] Step 1114: The target access network device sends a handover request response to the target AMF.

[0297] Specifically, the handover request response may be a handover request ACK.

[0298] The handover request response may include tunnel information allocated by the target access network device, which may be used to establish a tunnel from the I-UPF to the target access network device so that the I-UPF can send data to the target access network device. Specifically, the tunnel information may be access network tunnel information AN tunnel Info.

[0299] The handover request response may also include identification information of the unicast QoS flow for which the air interface resources are successfully created. Exemplarily, the target access network device allocates corresponding air interface resources based on the QoS information corresponding to the unicast QoS flow included in the N2 session management information, for example, data radio bearer (DRB) configuration information. The DRB configuration information may include configuration information from the PDCP layer to the PHY layer, such as whether the PDCP layer requires encryption, whether the RLC layer adopts acknowledged mode (AM) mode or unacknowledged mode (UM) mode, the scheduling policy of the MAC layer, or the modulation and coding mode of the PHY layer.

[0300] The handover request response may also include access configuration information, which is used by the UE to access the target access network device. For example, the access configuration information may include at least one of the following information: C-RNTI, radio bearer configuration information for a unicast QoS flow, or radio bearer configuration information for a unicast QoS flow corresponding to a multicast / broadcast QoS flow.

[0301] It should be noted that, if the target access network device supports multicast / broadcast, the access configuration information may also include radio bearer configuration information of the multicast / broadcast QoS flow.

[0302] Step 1115: The target AMF sends a PDU session context update request to the target I-SMF.

[0303] Specifically, the PDU session context update request may be Nsmf_PDUSession_Update Request.

[0304] The PDU session context update request may include tunnel information allocated by the target access network device and may also include access configuration information.

[0305] Step 1116: The target I-SMF sends an N4 session modification request to the target I-UPF.

[0306] The N4 session modification request includes tunnel information allocated by the target access network device.

[0307] Step 1117: The target I-UPF sends an N4 session modification response (N4 session modification response) to the target I-SMF.

[0308] Step 1118: The target I-SMF sends a PDU session context update response to the target AMF.

[0309] Specifically, the PDU session context update response may be Nsmf_PDUSession_Update Response.

[0310] The PDU session context update response may include access configuration information.

[0311] Step 1119: The target AMF sends a UE context creation response to the source AMF.

[0312] Specifically, the UE context creation response may be Namf_Communication_CreateUEContextResponse.

[0313] The UE context creation response may include access configuration information.

[0314] Step 1120: The source AMF sends a handover command to the source access network device.

[0315] The handover command may include access configuration information.

[0316] Step 1121: The source access network device sends a handover command to the UE.

[0317] The handover command may include access configuration information.

[0318] Step 1122: The UE accesses the target access network device according to the access configuration information and receives service data from the target access network device.

[0319] The service data may be, for example, multicast / broadcast service data.

[0320] It should be noted that if the target access network device does not support multicast / broadcast, the target access network device may send multicast / broadcast service data to the UE through a PDU session.

[0321] Step 1123: The target access network device sends a handover notify to the target AMF.

[0322] The switching notification is used to notify the target AMF of the successful switching to the target access network device.

[0323] Step 1124: The target AMF sends a PDU session context update request to the target I-SMF.

[0324] Specifically, the PDU session context update request may be used to notify the UE of successful handover to the target access network device.

[0325] Step 1125, the target I-SMF interacts with the MB-SMF to establish the first tunnel.

[0326] The first tunnel is described in the foregoing, which will not be repeated here.

[0327] Step 1126, the target I-SMF sends a PDU session update request to the SMF.

[0328] Specifically, the PDU session update request can be Nsmf_PDUSession_Update Request.

[0329] The PDU session update request can include second information. The second information is described in the foregoing, which will not be repeated here.

[0330] Step 1127, the SMF sends an N4 session modification request to the PSA UPF.

[0331] The N4 session modification request can be the first message mentioned in the foregoing embodiments, and the N4 session modification request is used to trigger the PSA PDU to release resources for transmitting data of the multicast / broadcast service. The first message is described in the foregoing, which will not be repeated here.

[0332] Example four: a scenario in which the UE performs an SR procedure

[0333] Step 1201, the UE sends a service request to the access network device.

[0334] The service request can include identification information of the UE, location information of the UE, and identification information (such as a PDU session ID) of a PDU session that needs to be activated.

[0335] The identification information of the UE and the location information of the UE can refer to the foregoing description, which will not be repeated here.

[0336] Step 1202, the access network device sends an N2 message to the AMF.

[0337] The N2 message can include location information of the UE and identification information of the PDU session that needs to be activated.

[0338] Step 1203, the AMF selects a target I-SMF.

[0339] For example, if the UE is located outside the service area of ​​the source I-SMF, the AMF may determine to insert a target I-SMF and may select the target I-SMF through the NRF. For example, the AMF may select an SMF whose service area covers the location of the UE as the target I-SMF.

[0340] Step 1204: AMF sends a PDU session context establishment request to the target I-SMF.

[0341] Specifically, the PDU session context establishment request may be Nsmf_PDUSession_CreateSMContextRequest.

[0342] The PDU session context establishment request may include identification information of the PDU session and identification information of the source I-SMF (such as SMF ID).

[0343] Step 1205: The target I-SMF sends a PDU session context request to the source I-SMF according to the identification information of the source I-SMF and the identification information of the PDU session.

[0344] Specifically, the PDU session context request may be Nsmf_PDUSession_Context Request.

[0345] The PDU session context request may include identification information of the PDU session.

[0346] If the source I-SMF does not support multicast / broadcast, the following steps 1206 to 1214 are continued to be executed.

[0347] Step 1206: The source I-SMF sends a PDU session context response message to the target I-SMF.

[0348] Specifically, the PDU session context response message may be Nsmf_PDUSession_Context Response.

[0349] If the target I-SMF supports multicast / broadcast, the following steps 1207 to 1214 are continued to be executed.

[0350] Step 1207: The target I-SMF sends an N4 session establishment request (N4 session establishment request) to the target I-UPF.

[0351] The N4 session establishment request is used to request the target I-UPF to allocate tunnel information, and the tunnel information allocated by the target I-UPF is used to establish a tunnel between the target I-UPF and the source I-UPF. Specifically, the tunnel information can be core network tunnel information CN tunnel Info.

[0352] Step 1208: The target I-UPF sends an N4 session establishment response (N4 session establishment response) to the target I-SMF.

[0353] The N4 session establishment response may include tunnel information allocated by the target I-UPF.

[0354] Step 1209: The target I-SMF sends a PDU session context update request to the source I-SMF.

[0355] Specifically, the PDU session context update request may be Nsmf_PDUSession_UpdateSMContextRequest.

[0356] The PDU session context update request may include tunnel information allocated by the target I-UPF.

[0357] Step 1210: The source I-SMF sends an N4 session modification request (N4 session modification request) to the source I-UPF.

[0358] The N4 session modification request may include tunnel information allocated by the target I-UPF so that the source I-UPF sends data to the target I-UPF.

[0359] Step 1211: The source I-UPF sends an N4 session modification response (N4 session modification response) to the source I-SMF.

[0360] Step 1212: The source I-SMF sends a PDU session context update response to the target I-SMF.

[0361] Specifically, the PDU session context update response may be Nsmf_PDUSession_UpdateSMContextResponse.

[0362] Step 1213: The target I-SMF sends a PDU session update request to the SMF.

[0363] Specifically, the PDU session update request may be Nsmf_PDUSession_Update Request.

[0364] If the target I-SMF supports multicast / broadcast, the PDU session update request may include multicast / broadcast capability information, where the multicast / broadcast capability information is used to indicate that the target I-SMF supports multicast / broadcast.

[0365] Step 1214: The SMF determines that the PDU session is associated with the multicast / broadcast service and sends a PDU session update response to the target I-SMF.

[0366] Specifically, the PDU session update response may be Nsmf_PDUSession_Update Response.

[0367] In one embodiment, the SMF may determine that the PDU session is associated with the multicast / broadcast service based on the identification information of the multicast / broadcast service (such as MBS session ID) included in the session management context of the PDU session. In another embodiment, the SMF stores the multicast / broadcast session context of the multicast / broadcast service and may determine that the PDU session is associated with the multicast / broadcast service based on the identification information of the UE (such as SUPI) included in the multicast / broadcast session context.

[0368] The PDU session update response may include the first information. For an introduction to the first information, please refer to the relevant description above, which will not be repeated here.

[0369] The present application also provides a communication device, please refer to Figure 13 , is a structural diagram of a communication device provided in an embodiment of the present application, the communication device 1300 includes: a transceiver module 1310 and a processing module 1320. The communication device can be used to implement the functions of a session management function network element or an intermediate session management function network element in any of the above method embodiments. The session management function network element can be Figure 4 SMF in, or Figure 6 The source I-SMF in, or Figure 8 A-SMF in, or Figures 9 to 12 The SMF in the middle session management function network element can be Figure 4 I-SMF in, or Figure 6 The target I-SMF in, or Figure 8 The target I-SMF in, or Figures 9 and 10 I-SMF in, or Figures 11 to 12 The communication device may be a network device, or a device capable of supporting the network device to implement the corresponding functions in the above method embodiment (eg, a chip included in the network device).

[0370] For example, when the communication device executes Figure 4In the method embodiment shown in , when the operation or step of the session management function network element corresponds, the transceiver module 1310 is used to send first information to the intermediate session management function network element, the first information including information of the first multicast / broadcast service, and the communication device is used to control the PDU session anchor point of the protocol data unit PDU session associated with the terminal device and the first multicast / broadcast service; and to receive second information from the intermediate session management function network element, the second information being used to indicate that a first tunnel has been established, the first tunnel being used to transmit data of the first multicast / broadcast service between the intermediate user plane function network element and the multicast / broadcast user plane function network element, and the intermediate session management function network element being used to control the intermediate user plane function network element.

[0371] In one possible design, the transceiver module 1310 is also used to receive multicast / broadcast capability information from the intermediate session management function network element, and the multicast / broadcast capability information is used to indicate whether the intermediate session management function network element supports multicast / broadcast; the processing module 1320 is used to send the first information to the intermediate session management function network element through the transceiver module 1310 based on the multicast / broadcast capability information.

[0372] In one possible design, the processing module 1320 is also used to send a first message to the PDU session anchor through the transceiver module 1310 based on the second information. The first message is used to trigger the PDU session anchor to release resources used to transmit data for the first multicast / broadcast service.

[0373] When the communication device executes Figure 4 In the method embodiment shown in , when the operation or step of the intermediate session management function network element corresponds to the operation or step of the intermediate session management function network element, the transceiver module 1310 is used to receive first information from the session management function network element, the first information including information of the first multicast / broadcast service, and the session management function network element is used to control the PDU session anchor point of the protocol data unit PDU session associated with the terminal device and the first multicast / broadcast service; the processing module 1320 is used to send second information to the session management function network element through the transceiver module 1310 according to the first information, the second information is used to indicate that the first tunnel has been established, the first tunnel is used to transmit data of the first multicast / broadcast service between the intermediate user plane function network element and the multicast / broadcast user plane function network element, and the communication device is used to control the intermediate user plane function network element.

[0374] In one possible design, the method further includes: the intermediate session management function network element sending multicast / broadcast capability information of the intermediate session management function network element to the session management function network element, where the multicast / broadcast capability information is used to indicate whether the intermediate session management function network element supports multicast / broadcast.

[0375] In one possible design, the processing module 1320 is also used to send a second message to the intermediate user plane functional network element through the transceiver module 1310, and the second message is used to trigger the intermediate user plane functional network element to configure resources for transmitting data of the first multicast / broadcast service.

[0376] The processing module 1320 involved in the communication device can be implemented by at least one processor or processor-related circuit components, and the transceiver module 1310 can be implemented by at least one transceiver or transceiver-related circuit components or communication interfaces. The operations and / or functions of each module in the communication device are respectively to achieve Figures 4 to 12 For the sake of brevity, the corresponding process of the method shown in FIG. is not repeated here. Optionally, the communication device may further include a storage module, which may be used to store data and / or instructions. The transceiver module 1310 and / or the processing module 1320 may read the data and / or instructions in the storage module, thereby enabling the communication device to implement the corresponding method. The storage module may be implemented, for example, by at least one memory.

[0377] The above-mentioned storage module, processing module and transceiver module may exist separately, or all or part of the modules may be integrated, for example, the storage module and the processing module are integrated, or the processing module and the transceiver module are integrated.

[0378] Please refer to Figure 14 , is another structural diagram of a communication device provided in an embodiment of the present application. The communication device can be used to implement the functions corresponding to the session management function network element or the intermediate session management function network element in the above method embodiment. Among them, the session management function network element can be Figure 4 SMF in, or Figure 6 The source I-SMF in, or Figure 8 A-SMF in, or Figures 9 to 12 The SMF in the middle session management function network element can be Figure 4 I-SMF in, or Figure 6 The target I-SMF in, or Figure 8 The target I-SMF in, or Figures 9 and 10 I-SMF in, or Figures 11 to 12 The communication device may be a network device or a device capable of supporting the network device to implement the corresponding functions in the above method embodiment (eg, a chip included in the network device).

[0379] The communication device 1400 may include a processor 1401 and a memory 1402. The memory 1402 is used to store program instructions and / or data, and the processor 1401 is used to execute the program instructions stored in the memory 1402, thereby implementing the method in the above method embodiment.

[0380] Optionally, the memory 1402 and the processor 1401 are coupled, the coupling is an indirect coupling or a communication connection between devices, units or modules, which can be electrical, mechanical or other forms, for information interaction between devices, units or modules.

[0381] Optionally, the communication device 1400 can further include a communication interface 1403, which is used to communicate with other devices through a transmission medium, such as transmitting the received signal from other communication devices to the processor 1401, or transmitting the signal from the processor 1401 to other communication devices. The communication interface 1403 can be a transceiver, or an interface circuit such as a transceiver circuit, a transceiver chip, etc.

[0382] In an embodiment, the communication interface 1403 can be specifically used to perform the actions of the above-mentioned transceiver module 1310, and the processor 1401 can be specifically used to perform the actions of the above-mentioned processing module 1320, which will not be repeated here.

[0383] The specific connection medium between the processor 1401, the memory 1402 and the communication interface 1403 is not limited in the embodiments of the present application. In the embodiments of the present application Figure 14 , the processor 1401, the memory 1402 and the communication interface 1403 are connected through a bus 1404, and the bus is represented by a thick line in Figure 14 , the connection mode between other components is only schematically illustrated and is not limited. The bus can be divided into an address bus, a data bus, a control bus, etc. For convenience, Figure 14 , only one thick line is used to represent, but it does not mean that there is only one bus or only one type of bus.

[0384] The embodiments of the present application also provide a chip system, comprising: a processor, the processor is coupled with a memory, the memory is used to store programs or instructions, when the programs or instructions are executed by the processor, the chip system realizes the method corresponding to the session management function network element or the intermediate session management function network element in any one of the above-mentioned method embodiments.

[0385] Optionally, the processor in the chip system can be one or more. The processor can be realized by hardware or software. When realized by hardware, the processor can be a logic circuit, an integrated circuit, etc. When realized by software, the processor can be a general-purpose processor, which realizes by reading the software code stored in the memory.

[0386] Optionally, the memory in the chip system may be one or more. The memory may be integrated with the processor or may be provided separately from the processor, which is not limited in this application. Exemplarily, the memory may be a non-transient processor, such as a read-only memory (ROM), which may be integrated with the processor on the same chip or provided on different chips. This application does not specifically limit the type of memory or the configuration of the memory and the processor.

[0387] Exemplarily, the chip system can be a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), a system on chip (SoC), a central processor unit (CPU), a network processor (NP), a digital signal processor (DSP), a microcontroller unit (MCU), a programmable logic device (PLD) or other integrated chips.

[0388] It should be understood that each step in the above method embodiment can be completed by hardware integrated logic circuits in a processor or by software instructions. The method steps disclosed in the embodiments of the present application can be directly embodied as being executed by a hardware processor, or by a combination of hardware and software modules in a processor.

[0389] An embodiment of the present application further provides a computer-readable storage medium, wherein the computer storage medium stores a computer program or instruction. When the computer program or instruction is executed, the communication device executes the method in any of the above method embodiments.

[0390] An embodiment of the present application further provides a computer program product. When a communication device reads and executes the computer program product, the communication device executes a method in any of the above method embodiments.

[0391] The present application also provides a communication system including a session management function network element and an intermediate session management function network element. Optionally, the communication system may also include one or more of an anchor user plane function network element, an intermediate user plane function network element, a multicast / broadcast session management function network element, and a multicast / broadcast user plane function network element.

[0392] It should be understood that the processor mentioned in the embodiments of the present application may be a CPU, or may be other general-purpose processors, DSPs, ASICs, FPGAs or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor.

[0393] It should also be understood that the memory mentioned in the embodiments of the present application may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memories. Among them, the non-volatile memory may be a ROM, a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or a flash memory. The volatile memory may be a random access memory (RAM), which is used as an external cache. By way of example and not limitation, many forms of RAM are available, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous link dynamic random access memory (SLDRAM), and direct rambus RAM (DRRAM).

[0394] It should be noted that when the processor is a general-purpose processor, DSP, ASIC, FPGA or other programmable logic device, discrete gate or transistor logic device, discrete hardware component, the memory (storage module) is integrated into the processor.

[0395] It should be noted that the memory described herein is intended to include, but not be limited to, these and any other suitable types of memory.

[0396] It should be understood that the various numerical numbers involved in the various embodiments of the present application are only for the convenience of description. The size of the serial numbers of the above-mentioned processes or steps does not mean the order of execution. The execution order of each process or step should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0397] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0398] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0399] In the several embodiments provided in this application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are merely schematic. For example, the division of the units is merely a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0400] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0401] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0402] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes various media that can store program codes, such as a USB flash drive, a mobile hard disk, a ROM, a RAM, a magnetic disk, or an optical disk.

[0403] In the various embodiments of the present application, unless otherwise specified or there is a logical conflict, the terms and / or descriptions between different embodiments are consistent and can be referenced by each other. The technical features in different embodiments can be combined to form new embodiments according to their inherent logical relationships.

Claims

1. A multicast / broadcast session management method, characterized in that: The method comprises: The session management function network element sends first information to the intermediate session management function network element, where the first information includes information about the first multicast / broadcast service, and the session management function network element is used to control a PDU session anchor point of a protocol data unit (PDU) session associated with the terminal device and the first multicast / broadcast service; The session management function network element receives second information from the intermediate session management function network element, where the second information is used to indicate that a first tunnel has been established, where the first tunnel is used to transmit data of the first multicast / broadcast service between the intermediate user plane function network element and the multicast / broadcast user plane function network element, and where the intermediate session management function network element is used to control the intermediate user plane function network element.

2. The method according to claim 1, characterized in that The first tunnel is a direct tunnel between the intermediate user plane function network element and the multicast / broadcast user plane function network element.

3. The method according to claim 1, characterized in that The first information includes first indication information, where the first indication information is used to trigger the intermediate session management function network element to establish the first tunnel, or the first indication information is used to query the intermediate session management function network element whether the first tunnel has been established.

4. The method according to claim 1, wherein The second information includes information of the first multicast / broadcast service.

5. The method according to claim 1, wherein The information of the first multicast / broadcast service includes one or more of the following information: The identification information of the first multicast / broadcast service, the identification information of the regional session of the first multicast / broadcast service, the multicast / broadcast service quality QoS information of the first multicast / broadcast service, or the unicast QoS information corresponding to the multicast / broadcast QoS information of the first multicast / broadcast service.

6. The method according to claim 1, characterized in that The method further comprises: The session management function network element receives multicast / broadcast capability information from the intermediate session management function network element, where the multicast / broadcast capability information is used to indicate whether the intermediate session management function network element supports multicast / broadcast; The session management function network element sends first information to the intermediate session management function network element, including: The session management function network element sends the first information to the intermediate session management function network element according to the multicast / broadcast capability information.

7. The method according to any one of claims 1 to 6, characterized in that The method further comprises: The session management function network element sends a first message to the PDU session anchor point based on the second information, where the first message is used to trigger the PDU session anchor point to release resources used to transmit data of the first multicast / broadcast service.

8. A multicast / broadcast session management method, characterized in that: The method comprises: The intermediate session management function network element receives first information from the session management function network element, where the first information includes information about a first multicast / broadcast service, and the session management function network element is used to control a PDU session anchor point of a protocol data unit (PDU) session associated with a terminal device and the first multicast / broadcast service; The intermediate session management function network element sends second information to the session management function network element based on the first information, where the second information is used to indicate that a first tunnel has been established, and the first tunnel is used to transmit data of the first multicast / broadcast service between the intermediate user plane function network element and the multicast / broadcast user plane function network element, and the intermediate session management function network element is used to control the intermediate user plane function network element.

9. The method according to claim 8, characterized in that The first tunnel is a direct tunnel between the intermediate user plane function network element and the multicast / broadcast user plane function network element.

10. The method according to claim 8, characterized in that The first information includes first indication information; The method further comprises: The intermediate session management function network element establishes the first tunnel according to the first indication information, or queries whether the first tunnel has been established.

11. The method according to claim 8, characterized in that The second information includes information of the first multicast / broadcast service.

12. The method according to claim 8, characterized in that The information of the first multicast / broadcast service includes one or more of the following information: The identification information of the first multicast / broadcast service, the identification of the regional session of the first multicast / broadcast service, the multicast / broadcast service quality QoS information of the first multicast / broadcast service, or the unicast QoS information corresponding to the multicast-broadcast QoS information of the first multicast / broadcast service.

13. The method according to claim 8, characterized in that The method further comprises: The intermediate session management function network element sends multicast / broadcast capability information of the intermediate session management function network element to the session management function network element, where the multicast / broadcast capability information is used to indicate whether the intermediate session management function network element supports multicast / broadcast.

14. The method according to any one of claims 8 to 13, characterized in that The method further comprises: The intermediate session management function network element sends a second message to the intermediate user plane function network element, where the second message is used to trigger the intermediate user plane function network element to configure resources for transmitting data of the first multicast / broadcast service.

15. A communication device, characterized in that: Comprising means for executing the method according to any one of claims 1 to 7.

16. A communication device, characterized in that: Comprising means for performing the method as claimed in any one of claims 8 to 14.

17. A communication device, characterized in that: The apparatus comprises a processor and a memory, wherein the processor and the memory are coupled, and the processor is configured to control the apparatus to implement the method according to any one of claims 1 to 7.

18. A communication device, characterized in that: The apparatus comprises a processor and a memory, wherein the processor and the memory are coupled, and the processor is configured to control the apparatus to implement the method according to any one of claims 8 to 14.

19. A computer-readable storage medium, characterized in that The storage medium stores a computer program or instruction. When the computer program or instruction is executed by the communication device, the method according to any one of claims 1 to 7 or 8 to 14 is implemented.

20. A communication system, characterized in that: The method comprises the communication device according to claim 15 or 17, and the communication device according to claim 16 or 18.

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