Satellite switching method and device, storage medium and chip system

Abstract

A satellite switching method and device, a storage medium and a chip system, relate to the field of communication technology, and are used for reducing signaling overhead and delay in a switching process of a first terminal device. In the present application, a first communication device sends a first request message to other devices in a case where it is estimated that the first terminal device will switch from a source access network device to a first target access network device at a future time. The first request message indicates that a PDU session of the first terminal device is estimated to switch at the future time, or the first request message indicates that the first terminal device is estimated to switch at the future time. In this way, other devices can prepare for the switching of the first terminal device in advance, thereby reducing the signaling overhead in the switching process of the first terminal device, and thus reducing the delay in the switching process of the first terminal device.

Description

Technical Field

[0001] This application relates to the field of communication technology, and in particular to a satellite switching method, apparatus, storage medium and chip system. Background Technology

[0002] In the research of 5G and 6G communication systems, satellite communication has gradually become a research hotspot. Satellite communication can supplement some scenarios that are difficult to cover by terrestrial communication, such as deserts and oceans. Satellite communication scenarios may involve the deployment of network elements that were originally located on the ground to satellites, such as the deployment of radio access network (RAN) equipment and user plane function (UPF) network elements to satellites.

[0003] In scenarios where RAN equipment and UPF network elements are deployed on satellites, when the terminal equipment remains stationary or does not move rapidly, it needs to switch between the RAN equipment and UPF network elements as the satellite moves. Currently, the terminal equipment switching process requires a large amount of space-to-ground communication, such as multiple space-to-ground communications to establish tunnel information for Protocol Data Unit (PDU) sessions. This switching process currently incurs significant signaling overhead and severe latency, seriously impacting the service experience. Summary of the Invention

[0004] This application provides a satellite handover method, apparatus, storage medium, and chip system to reduce signaling overhead and latency during the handover process between satellite devices for terminal devices.

[0005] In a first aspect, embodiments of this application provide a satellite handover method. This method can be executed by an access and mobility management function (AMU) network element or a module (such as a chip) applied to an AMU network element, and can also be executed by a source access network device or a module (such as a chip) applied to a source access network device. The method includes:

[0006] A first communication device anticipates that a first terminal device will switch from a source access network device to a first destination access network device at a future time. The first communication device sends a first request message. The first request message indicates that the protocol data unit (PDU) session of the first terminal device is anticipated to be switched at a future time, or that the first terminal device is anticipated to be switched at a future time. The source user plane function network element and the source access network device, which provide services for the PDU session prior to the switch, are deployed on the first satellite.

[0007] Since the source access network equipment and the source user plane function network element are located on the same satellite, when the first terminal equipment needs to switch access network equipment in the future, it also needs to switch user plane function network elements. In this application, the first communication device can send a first request message to other devices when it is anticipated that the first terminal equipment will switch. Other devices can then prepare for the switch of the first terminal equipment in advance, such as by configuring information in advance (e.g., establishing tunnel information for the switch of the first terminal equipment). When the first terminal equipment subsequently switches, it can use the pre-configured information, thereby reducing the signaling overhead of space-to-ground communication during the switch process and thus reducing the latency of the switch process.

[0008] In one possible implementation, the first request message indicates the establishment of a user plane path after the PDU session handover. This allows for the establishment of a user plane path for the PDU session in advance, anticipating that the first terminal device will be handover at a future time. This saves on signaling required for establishing the user plane path during the handover process, thereby reducing handover latency.

[0009] In one possible implementation, the first communication device predicts that the first terminal device will switch from the source access network device to the first target access network device at a future time, including: the first communication device predicts that the first terminal device will switch from the source access network device to the first target access network device at a future time based on the location information of the first terminal device and the motion trajectory of the first satellite.

[0010] In this way, the first communication device does not need to rely on information sent by other devices for prediction, thereby reducing signaling interaction.

[0011] In one possible implementation, the first communication device predicts that a first terminal device will switch from a source access network device to a first target access network device at a future time. This includes: the first communication device receiving a second request message, which indicates that the first terminal device is predicted to switch from the source access network device to the first target access network device at a future time. Based on the second request message, the first communication device predicts the switch from the source access network device to the first target access network device at a future time. In this way, the first communication device does not need to perform the prediction itself based on the location information of the first terminal device and the motion trajectory of the first satellite, thereby reducing the load on the first communication device.

[0012] In one possible implementation, the first request message includes at least one of the following: information about a first target access network device, information about a first target user plane function network element, or information about a second satellite. The first target access network device and the first target user plane function network element are deployed on the second satellite.

[0013] In other words, the first request message can explicitly or implicitly indicate the first target user plane function network element, enabling other devices to configure the PDU session context for the first terminal device within the first target user plane function network element. To reduce cross-satellite communication, the first target user plane function network element and the first target access network device can be deployed on the same satellite. When the first request message includes information about the first target access network device, the first communication device can select the first target user plane function network element based on that information. When the first request message includes information about a second satellite, the first communication device can directly select the user plane function network element on the second satellite as the first target user plane function network element.

[0014] In one possible implementation, after the first communication device sends the first request message, it further includes: the first communication device determining that the first terminal device has switched to the first target access network device. The first communication device sends a third request message, which indicates that the PDU session has been switched (the PDU session being switched can be understood as the user plane path after the PDU session switch has been established). Since the first communication device anticipates in advance that the first terminal device will switch to the first target access network device, it triggers other devices to prepare for the switch of the first terminal device in advance. Therefore, when the first communication device determines that the first terminal device has actually switched, the first communication device can issue an indication that the PDU session has been switched, thereby avoiding other devices from repeatedly configuring the context for the PDU session.

[0015] In one possible implementation, the first communication device determines that the first terminal device has switched to the first target access network device, including: the first communication device receiving a first path switching request message, the first path switching request message indicating that the PDU session of the first terminal device has been switched (the PDU session being switched can be understood as the user plane path after the PDU session switching has been established); the first communication device determines that the first terminal device has switched to the first target access network device based on the first path switching request message.

[0016] For example, the first path switching request message may carry a list of active user plane PDU sessions, where the PDU sessions in the list are those for which user plane paths have been established. In this case, if the first communication device determines that a PDU session is included in the list of active user plane PDU sessions, it can determine that the user plane path for that PDU session after the switch has been established.

[0017] For example, the first path switching request message may carry a list of PDU sessions to be activated in the user plane, where the PDU sessions in the list are those for which the user plane path has not yet been established. In this case, if the first communication device determines that a PDU session is not included in the list of PDU sessions to be activated in the user plane, it can assume that the user plane path for that PDU session has been established after the switch. In this application, the establishment of the user plane path can be understood as the user plane being activated.

[0018] Because the first communication device anticipates in advance that the first terminal device will switch to the first target access network device, it triggers other devices to prepare for the handover of the first terminal device in advance. Consequently, the first path handover request message can carry an indication that the PDU session of the first terminal device has been switched (a PDU session switch can be understood as the user plane path after the PDU session switch has been established). Since the first path handover request message carries an indication that the PDU session of the first terminal device has been switched (a PDU session switch can be understood as the user plane path after the PDU session switch has been established), the process of determining whether the PDU session has been switched by the first communication device is eliminated, thereby reducing the load on the first communication device.

[0019] In one possible implementation, the first communication device may make a miscalculation, for example, it may anticipate that the first terminal device will be switching to the first target access network device, but during the subsequent handover process, the first terminal device switches to the second target access network device. In this case, preparations for the first terminal device to switch to the second target access network device need to be redone. For example, after sending a first request message, the first communication device determines that the first terminal device is switching to the second target access network device. The second target access network device is different from the first target access network device. The first communication device sends a fourth request message, which indicates that the PDU session is pending handover (the PDU session pending handover can be understood as the user plane path after the PDU session handover is pending establishment). In this way, other devices can prepare for the first terminal device to switch to the second target access network device based on the fourth request message.

[0020] In one possible implementation, the first communication device determines that a first terminal device is switching to a second target access network device, including: the first communication device receiving a second path switching request message from the second target access network device, the second path switching request message instructing the first terminal device to switch to the second target access network device. The second path switching request message may further include a list of PDU sessions to be activated in the user plane, which includes PDU sessions for which a user plane path needs to be established. If a PDU session of the first terminal device is included in the list of PDU sessions to be activated, it indicates that the user plane path for that PDU session after the switch has not yet been established. That is, based on the second path switching request message, the first communication device determines that the first terminal device has switched to the second target access network device and that a user plane path has not yet been established; therefore, a user plane path needs to be established for the first terminal device.

[0021] In one possible implementation, the first communication device sends a first request message, including: the first communication device sending the first request message to a first target access network device, the first request message further being used to request the first target access network device to allocate radio resources for the first terminal device; the first communication device receiving information about the radio resources allocated to the first terminal device. After the first communication device sends the first request message, the method further includes: the first communication device determining that the first terminal device switches to the first target access network device; the first communication device sending a Radio Resource Control (RRC) reconfiguration request message to the first terminal device, the RRC reconfiguration request message including information about the radio resources.

[0022] Since the first communication device requests the first target access network device to allocate radio resources for the first terminal device in advance when it anticipates that the first terminal device is about to switch to the first target access network device, the step of requesting the first target access network device to allocate radio resources can be omitted during the process of determining the actual switch of the first terminal device, thereby reducing the latency of the switchover process.

[0023] In one possible implementation, the first communication device sends a first request message to the session management function network element. This allows the session management function network element to establish a context for the PDU session of the first terminal device in advance based on the first request message.

[0024] In another possible implementation, the first communication device sends a first request message to the access and mobility management network element. This allows the access and mobility management network element to prepare for the handover of the first terminal device in advance based on the first request message. For example, the access and mobility management network element can also trigger other network elements (such as session management function network elements) to prepare for the handover of the first terminal device in advance based on the first request message.

[0025] In another possible implementation, the first communication device sends a first request message to the first target access network device. This allows the first target access network device to prepare for the handover of the first terminal device in advance based on the first request message. For example, the first target access network device can allocate radio resources in advance for the handover of the first terminal device; or the first target access network device can trigger other network elements to prepare for the handover of the first terminal device in advance based on the first request message.

[0026] Secondly, embodiments of this application provide a satellite handover method, comprising: a session management function network element receiving a first request message, the first request message indicating that a Protocol Data Unit (PDU) session of a first terminal device is expected to be handed over at a future time; a source user plane function network element and a source access network device providing services for the PDU session before the handover are deployed on a first satellite. The session management function network element sends a fifth request message, the fifth request message requesting the establishment of a context for the PDU session in a first target user plane function network element. The first target user plane function network element is a user plane function network element selected by the session management function network element to provide services for the PDU session after the handover; the first target user plane function element and the first target access network device providing services for the PDU session after the handover are deployed on a second satellite.

[0027] When the session management network element receives the first request message, it can request to establish the context of the PDU session in the first target user plane function network element, thereby preparing for the handover of the first terminal device in advance. Then, when the first terminal device undergoes a handover process, it can use the pre-configured information, thereby reducing the signaling overhead of the ground-to-ground communication during the handover process of the first terminal device, and thus reducing the latency of the handover process of the first terminal device.

[0028] In one possible implementation, the fifth request message includes: the context of the PDU session corresponding to the first target user plane function network element; and / or, the context of the PDU session corresponding to the first target access network device. The context of the PDU session corresponding to the first target user plane function network element and the context of the PDU session corresponding to the first target access network device are used for communication between the first target user plane function network element and the first target access network device.

[0029] Thus, the context of the PDU session corresponding to the first target user plane function network element; and / or the context of the PDU session corresponding to the first target access network device can be allocated by the session management network element, thereby reducing the workload of the first target user plane function network element and / or the first target access network device.

[0030] In one possible implementation, the first request message includes at least one of the following: information about a first target access network device, information about a first target user plane function network element, or information about a second satellite. The first target access network device and the first target user plane function network element are deployed on the second satellite. The beneficial effects are described above and will not be repeated here.

[0031] In one possible implementation, after the session management function network element sends the fifth request message, the session management function network element receives the fifth response message, which indicates that the first target user plane function network element has configured the context of the PDU session.

[0032] In one possible implementation, after the session management function network element receives the fifth response message, it further includes: the session management function network element receiving a third request message. The third request message is used to request an update to the PDU session context. If the third request message indicates that the PDU session has been switched (a PDU session switch can be understood as the user plane path after the switch has been established), the session management function network element returns a third response message based on the indication information indicating that the PDU session has been switched. The third response message indicates that the PDU session context update is complete.

[0033] Since the third request message carries an indication that the PDU session has been switched, the SMF can determine that it has already completed the preparation work for the switch of the first terminal device in advance, and does not need to prepare for the switch of the PDU session of the first terminal device again. Therefore, it can directly return the third response message. Moreover, this scheme can save the process of the session management function network element to determine whether the PDU session has been switched, thereby reducing the load of the session management function network element.

[0034] In one possible implementation, when the third request message indicates that the PDU session is pending handover: the session management function network element can return a third response message based on the fifth response message, and the third response message indicates that the PDU session context update is complete.

[0035] Since the third request message carries an indication that the PDU session is waiting to be switched, the SMF can determine on its own whether it has already completed the preparation work for the switch of the first terminal device (such as the establishment of the user plane path). According to the fifth response message, it can be determined that the preparation work for the switch of the first terminal device has been completed in advance. Therefore, it is not necessary to prepare for the switch of the PDU session of the first terminal device again, so the third response message can be returned directly.

[0036] In one possible implementation, after the session management function network element receives the fifth response message, it further includes: the session management function network element receiving a fourth request message, which requests an update to the PDU session context. If the fourth request message indicates that the PDU session is awaiting handover (PDU session handover can be understood as the user plane path after the PDU session handover needs to be established): if the session management function network element determines that the PDU session is to be handed over to the second target user plane function network element, it sends a sixth request message, which requests the second target user plane function network element to configure the PDU session context.

[0037] Since prediction failures may occur in practical applications, in this application, when prediction fails, the SMF may need to re-prepare for the PDU session handover.

[0038] In one possible implementation, the context of the PDU session corresponding to the first target user plane function network element includes: N3 tunnel information of the PDU session of the first terminal device corresponding to the first target user plane function network element. In another possible implementation, the context of the PDU session corresponding to the first target user plane function network element includes N3 tunnel information and Nx tunnel information of the PDU session of the first terminal device corresponding to the first target user plane function network element.

[0039] In one possible implementation, after the session management function network element sends the fifth request message, it further includes: the session management function network element sending the Nx tunnel information of the PDU session corresponding to the first target user plane function network element to the user plane function network element of the second terminal device. Since the session management function network element sends the Nx tunnel information of the PDU session corresponding to the first target user plane function network element to the user plane function network element of the second terminal device in advance before the actual handover of the first terminal device, the step of the session management function network element sending the Nx tunnel information of the PDU session corresponding to the first target user plane function network element to the user plane function network element of the second terminal device in the subsequent handover process can be saved, thereby reducing the latency of the handover process.

[0040] In one possible implementation, after the session management function network element sends the fifth request message, the process further includes: the session management function network element receiving a first update message, the first update message including the estimated Nx tunnel information of the user plane function network element after the handover of the second terminal device. The session management function network element then sends the Nx tunnel information of the user plane function network element after the handover of the second terminal device to the first target user plane function network element. This eliminates the step of the session management function network element sending the Nx tunnel information of the user plane function network element after the handover of the second terminal device to the first target user plane function network element in the subsequent handover process, thereby reducing the handover process latency.

[0041] Thirdly, embodiments of this application provide a satellite handover method, the method comprising: a first target access network device receiving a first request message. The first request message indicates that a first terminal device is expected to be handed over at a future time. A source user plane function network element and a source access network device, providing services for the Protocol Data Unit (PDU) session of the first terminal device before the handover, are deployed on a first satellite. The first target access network device sends a seventh request message, the seventh request message indicating that the PDU session of the first terminal device is expected to be handed over to the first target access network device at a future time; the seventh request message includes indication information of a tunnel configured by the first target access network device for the PDU session.

[0042] When the first target access network device receives the first request message, it can establish the context of the first terminal device corresponding to the first target access network device, thereby preparing for the handover of the first terminal device in advance. Then, when the first terminal device undergoes a handover process, it can use the pre-configured information, thereby reducing the signaling overhead of the ground-to-ground communication during the handover process of the first terminal device, and thus reducing the latency of the handover process of the first terminal device.

[0043] In one possible implementation, after the first target access network device sends the seventh request message, the process further includes: the first target access network device sending a first response message to the source access network device. The first response message indicates that the first terminal device has completed the pre-handover. The first response message also includes RRC configuration information required for the first terminal device to access the first target access network device. Thus, the first target access network device can send the required RRC configuration information to the source access network device during the pre-handover phase, thereby saving the signaling costs incurred in obtaining this RRC configuration information during the handover process, and further reducing the handover latency.

[0044] In one possible implementation, after the first target access network device sends the seventh request message, the method further includes: the first target access network device receiving a seventh response message, the seventh response message including the context of the PDU session corresponding to the first target user plane function network element. The context of the first terminal device corresponding to the first target access network device and the context of the PDU session corresponding to the first target user plane function network element are used for communication between the first target access network device and the first target user plane function network element; the first target user plane function network element is a user plane function network element that is predicted to provide services for the PDU session after handover; the first target user plane function element and the first target access network device are deployed on the second satellite.

[0045] Since the first target access network device can request to establish the context of the PDU session in the first target user plane function network element when it receives the first request message, it can prepare for the handover of the first terminal device in advance. Then, when the first terminal device undergoes a handover process, it can use the pre-configured information, thereby reducing the signaling overhead of the ground-to-ground communication during the handover process of the first terminal device and reducing the handover latency of the first terminal device.

[0046] In one possible implementation, after the first target access network device receives the seventh response message, it further includes: the first target access network device receiving a message from the first terminal device indicating that the Radio Access Control (RRC) reconfiguration is complete. The first target access network device sends a first path switching request message, which indicates that the PDU session of the first terminal device has been switched (the PDU session being switched can be understood as the user plane path after the PDU session switch has been established).

[0047] Since the first path switching request message carries indication information indicating that the first terminal device has switched, the process of other devices determining whether the PDU session has been switched is eliminated, thereby reducing the load on the first communication device.

[0048] Fourthly, embodiments of this application provide a communication device, which may be an access and mobility management function network element, a source access network device, a session management function network element, or a first destination access network device, or a module (such as a chip) of any of these devices and network elements. The device has the function of implementing any of the methods described in the first aspect. This function can be implemented in hardware or by hardware executing corresponding software. The hardware or software includes one or more modules corresponding to the above-described function.

[0049] Fifthly, embodiments of this application provide a communication device, which may be an access and mobility management function network element, a source access network device, a session management function network element, or a first destination access network device, or a module (such as a chip) of any of these devices and network elements. The device may include a processor and a memory; the memory is used to store computer instructions, and when the device is running, the processor executes the computer instructions stored in the memory to cause the device to perform any of the implementation methods in the first to third aspects described above.

[0050] In a sixth aspect, embodiments of this application provide a communication apparatus, including units or means for performing each step of any of the implementation methods in the first to third aspects described above.

[0051] In a seventh aspect, embodiments of this application provide a communication apparatus, which may be an access and mobility management function network element, a source access network device, a session management function network element, or a first destination access network device, or a module (such as a chip) of any of these devices and network elements. The apparatus may include a processor and interface circuitry, the processor being used to communicate with other devices through the interface circuitry and to execute any of the implementation methods in the first to third aspects described above. The processor may include one or more processors.

[0052] Eighthly, embodiments of this application provide a communication apparatus, which may be an access and mobility management function network element, a source access network device, a session management function network element, or a first destination access network device, or a module (such as a chip) of any of these devices and network elements. The apparatus may include a processor coupled to a memory, the processor being used to invoke a program stored in the memory to execute any implementation method of the first to third aspects described above. The memory may be located within or outside the apparatus. Furthermore, the processor may be one or more.

[0053] Ninthly, embodiments of this application also provide a computer-readable storage medium storing instructions that, when executed on a communication device, cause any of the implementation methods of the first to third aspects to be performed.

[0054] In a tenth aspect, embodiments of this application also provide a computer program product, which includes a computer program or instructions that, when executed by a communication device, cause any of the implementation methods in the first to third aspects to be executed.

[0055] Eleventhly, embodiments of this application also provide a chip system, including: a processor, configured to execute any of the implementation methods of the first to third aspects described above.

[0056] The technical effects that can be achieved by any of the fourth to eleventh aspects mentioned above are the same as those that can be achieved by any of the first to third aspects mentioned above. The repetitions will not be discussed. Attached Figure Description

[0057] Figure 1 This is a schematic diagram of a 5G network architecture based on a service-oriented architecture.

[0058] Figure 2 This is a schematic diagram of a 5G network architecture based on a point-to-point interface.

[0059] Figure 3 This is a schematic diagram of the communication path between UEs;

[0060] Figure 4aA schematic flowchart illustrating a satellite handover method provided in an embodiment of this application;

[0061] Figure 4b A flowchart illustrating another satellite handover method provided in this application embodiment;

[0062] Figure 4c A flowchart illustrating another satellite handover method provided in this application embodiment;

[0063] Figure 5 A flowchart illustrating another satellite handover method provided in this application embodiment;

[0064] Figure 6 A flowchart illustrating another satellite handover method provided in this application embodiment;

[0065] Figure 7 A flowchart illustrating another satellite handover method provided in this application embodiment;

[0066] Figure 8 A flowchart illustrating another satellite handover method provided in this application embodiment;

[0067] Figure 9 A flowchart illustrating another satellite handover method provided in this application embodiment;

[0068] Figure 10 A schematic diagram of a communication device provided in an embodiment of this application;

[0069] Figure 11 A schematic diagram of another communication device provided in the embodiments of this application;

[0070] Figure 12 This is a schematic diagram of another communication device provided in an embodiment of this application. Detailed Implementation

[0071] To address the challenges of wireless broadband technology and maintain the leading edge of the 3rd Generation Partnership Project (3GPP) network, the 3GPP standards group developed the Next Generation System architecture, known as the 5G network architecture. This architecture not only supports radio access technologies defined by the 3GPP standards group (such as Long Term Evolution (LTE) and 5G Radio Access Network (RAN)) to access the 5G core network (CN), but also supports access to the core network using non-3GPP access technologies through non-3GPP interworking functions (N3IWF) or next-generation packet data gateways (ngPDG).

[0072] Figure 1 This is a schematic diagram of a 5G network architecture based on a service-oriented architecture. Figure 1The 5G network architecture shown may include access network equipment and core network equipment. Terminal devices access the data network (DN) through access network equipment and core network equipment. The core network equipment includes, but is not limited to, some or all of the following network elements: authentication server function (AUSF) network element (not shown in the figure), unified data management (UDM) network element, unified data repository (UDR) network element, network repository function (NRF) network element (not shown in the figure), network exposure function (NEF) network element (not shown in the figure), application function (AF) network element, policy control function (PCF) network element, access and mobility management function (AMF) network element, session management function (SMF) network element, user plane function (UPF) network element, and binding support function (BSF) network element (not shown in the figure).

[0073] Terminal devices can be user equipment (UE), mobile stations, mobile terminal devices, etc. They can be widely used in various scenarios, such as device-to-device (D2D), vehicle-to-everything (V2X) communication, machine-type communication (MTC), the Internet of Things (IoT), virtual reality, augmented reality, industrial control, autonomous driving, telemedicine, smart grids, smart furniture, smart offices, smart wearables, smart transportation, smart cities, etc. Terminal devices can include mobile phones, tablets, computers with wireless transceiver capabilities, wearable devices, vehicles, urban air mobility vehicles (such as drones, helicopters, etc.), ships, robots, robotic arms, smart home devices, etc.

[0074] Access network equipment can be either Radio Access Network (RAN) equipment or Wired Access Network (FAN) equipment. RAN equipment includes 3GPP access network equipment, untrusted non-3GPP access network equipment, and trusted non-3GPP access network equipment. 3GPP access network equipment includes, but is not limited to: evolved NodeBs (eNodeBs) in LTE, next-generation NodeBs (gNBs) in 5G mobile communication systems, base stations in future mobile communication systems, or modules or units that perform some base station functions, such as central units (CUs) and distributed units (DUs). Untrusted non-3GPP access network equipment includes, but is not limited to: untrusted non-3GPP access gateways or N3IWF devices, untrusted wireless local area network (WLAN) access points (APs), switches, and routers. Trusted non-3GPP access network equipment includes, but is not limited to: trusted non-3GPP access gateways, trusted WLAN APs, switches, and routers. Wired access network equipment includes, but is not limited to: wireline access gateway, fixed telephone network equipment, switches, and routers.

[0075] Access network equipment and terminal equipment can be fixed or mobile. They can be deployed on land, including indoors or outdoors, handheld or vehicle-mounted; they can also be deployed on water; and they can be deployed in the air on aircraft, balloons, and satellites. The embodiments of this application do not limit the application scenarios of the access network equipment and terminal equipment.

[0076] The AMF (Automatic Mobility Management) network element includes functions such as mobility management and access authentication / authorization. In addition, it is responsible for transmitting user policies between terminal devices and the PCF (Programmable Default Function) network element.

[0077] The SMF network element includes functions such as performing session management, executing control policies issued by the PCF, selecting the UPF, and allocating Internet Protocol (IP) addresses to terminal devices.

[0078] UPF network elements include functions such as user plane data forwarding, session / flow-based billing statistics, and bandwidth limiting.

[0079] UDM network elements include functions such as managing contracted data and authorizing user access.

[0080] UDR network elements include functions for storing and retrieving data of various types, such as contract data, policy data, and application data.

[0081] NEF network elements are used to support the opening of capabilities and events.

[0082] AF (Application Provider) network elements convey application-side requests to the network side, such as QoS requirements or user state event subscriptions. AF can be a third-party functional entity or an application service deployed by the operator, such as the IP Multimedia Subsystem (IMS) voice call service. AF network elements include those within the core network (i.e., the operator's AF network elements) and third-party AF network elements (such as an enterprise's application server).

[0083] PCF (Policy Control Function) network elements include policy control functions responsible for session and service flow-level billing, QoS bandwidth guarantee, mobility management, and terminal device policy decisions. PCF network elements include access and mobility management policy control function (AM PCF) network elements and session management policy control function (SM PCF) network elements. AM PCF network elements are used to formulate AM policies for terminal devices; AM PCF network elements can also be referred to as policy control network elements that provide services to terminal devices (PCF for a UE). SM PCF network elements are used to formulate session management policies (SM policies); SM PCF network elements can also be referred to as policy control network elements that provide services to a session (PCF for a PDU session).

[0084] NRF network elements can be used to provide network element discovery functionality, providing network element information corresponding to the network element type based on requests from other network elements. NRF also provides network element management services, such as network element registration, updates, deregistration, and network element status subscription and push.

[0085] The BSF network element can provide functions such as BSF service registration / deregistration / update, NRF connection detection, session binding information creation, UE information acquisition, and session binding information query for duplicate IP addresses.

[0086] The AUSF network element is responsible for authenticating users to determine whether to allow users or devices to access the network.

[0087] A Domain Provider (DN) is a network located outside of the carrier's network. A carrier's network can connect to multiple DNs, and various services can be deployed on a DN, providing data and / or voice services to terminal devices. For example, a DN might be the private network of a smart factory. Sensors installed in the workshop can act as terminal devices, and a control server for these sensors is deployed within the DN. The control server provides services to the sensors. Sensors can communicate with the control server, receive instructions from it, and transmit the collected sensor data back to the control server accordingly. Another example is a DN serving as an internal office network for a company. Employees' mobile phones or computers can act as terminal devices, accessing information and data resources on the company's internal office network.

[0088] Figure 1 Npcf, Nufr, Nudm, Naf, Namf, and Nsmf are the service interfaces provided by PCF, UDR, UDM, AF, AMF, and SMF, respectively, used to invoke the corresponding service operations. N1, N2, N3, N4, and N6 are interface sequence numbers, and their meanings are as follows:

[0089] 1) N1: The interface between the AMF and the terminal device, which can be used to transmit non-access stratum (NAS) signaling (such as QoS rules from the AMF) to the terminal device.

[0090] 2) N2: The interface between the AMF and the access network equipment, which can be used to transmit radio bearer control information from the core network side to the access network equipment.

[0091] 3) N3: The interface between the access network device and the UPF, mainly used to transmit uplink and downlink user plane data between the access network device and the UPF.

[0092] 4) N4: The interface between SMF and UPF, which can be used to transmit information between the control plane and the user plane, including the distribution of forwarding rules, QoS rules, traffic statistics rules, etc. from the control plane to the user plane, as well as the reporting of information from the user plane.

[0093] 5) N6: The interface between UPF and DN, used to transmit uplink and downlink user data streams between UPF and DN.

[0094] Figure 2 This is a schematic diagram of a 5G network architecture based on a point-to-point interface. For a description of the functions of the network elements, please refer to [reference needed]. Figure 2 The functions of the corresponding network elements will not be described in detail here. Figure 2 and Figure 1 The main difference is: Figure 1 The interfaces between the various control plane network elements are service-oriented interfaces. Figure 2 The interfaces between the various control plane network elements are point-to-point interfaces.

[0095] exist Figure 2 In the architecture shown, the interface names and functions between the various network elements are as follows:

[0096] 1) The meanings of interfaces N1, N2, N3, N4 and N6 can be found in the previous description.

[0097] 2) N5: The interface between the AF network element and the PCF network element, which can be used for application service request distribution and network event reporting.

[0098] 3) N7: The interface between PCF network elements and SMF network elements, which can be used to issue protocol data unit (PDU) session granularity and service data flow granularity control strategies.

[0099] 4) N8: The interface between the AMF network element and the UDM network element. It can be used by the AMF network element to obtain access and mobility management related subscription data and authentication data from the UDM network element, as well as by the AMF network element to register terminal device mobility management related information with the UDM network element.

[0100] 5) N9: User plane interface between UPF network elements, used to transmit uplink and downlink user data streams between UPF network elements.

[0101] 6) N10: The interface between SMF network elements and UDM network elements. It can be used for SMF network elements to obtain session management-related subscription data from UDM network elements, and for SMF network elements to register terminal device session-related information with UDM network elements.

[0102] 7) N11: The interface between SMF network elements and AMF network elements. It can be used to transmit PDU session tunnel information between access network devices and UPF, transmit control messages sent to terminal devices, and transmit radio resource control information sent to access network devices.

[0103] 8) N15: The interface between PCF network elements and AMF network elements, which can be used to issue terminal equipment policies and access control related policies.

[0104] 9) N35: Interface between UDM network element and UDR network element, which can be used by UDM network element to obtain user subscription data information from UDR network element.

[0105] 10) N36: The interface between PCF network elements and UDR network elements, which can be used by PCF network elements to obtain policy-related contract data and application data related information from UDR network elements.

[0106] It is understood that the aforementioned network element or function can be a network component in a hardware device, a software function running on dedicated hardware, or a virtualized function instantiated on a platform (e.g., a cloud platform). Optionally, the aforementioned network element or function can be implemented by one device, multiple devices working together, or a functional module within a single device; this application embodiment does not specifically limit this.

[0107] The user plane network element, mobility management network element, and session management network element in this application can be the UPF network element, AMF network element, and SMF network element in a 5G system, respectively, or they can be network elements in future communications such as 6G networks that have the functions of the aforementioned UPF network element, AMF network element, and SMF network element. This application does not limit them in this way. In the embodiments of this application, an example of a user plane network element, a mobility management network element, and a session management network element is used to describe the UPF network element, AMF network element, and SMF network element, respectively. Furthermore, the UPF network element, AMF network element, and SMF network element are abbreviated as UPF, AMF, and SMF, respectively.

[0108] For ease of explanation, in this embodiment, a base station (such as a 4G eNB, a 5G gNB, or a base station in future communications) is used as an example of an access network device. The term "base station" can be replaced with "access network device" in subsequent instances. "Source base station 1" can be replaced with "first access network device of the first terminal device." "Target base station 1" can be replaced with "first target access network device of the first terminal device." "Target base station 2" can be replaced with "second target access network device of the first terminal device." "Base station 2" can be replaced with "access network device of the second terminal device."

[0109] In this embodiment, UE is used as an example of a terminal device for illustration. Subsequent instances of "UE" can be replaced with "terminal device". "UE1" in this embodiment can be replaced with "first terminal device". "UE2" in this embodiment can be replaced with "second terminal device".

[0110] Based on the above, Figure 3 An exemplary schematic diagram of a possible satellite communication system architecture is shown, such as deploying base stations and UPFs on satellites. Figure 3 As shown, the communication path between UE1 and UE2 is: UE1->UE1's satellite base station 1->UE1's satellite UPF1->UE2's satellite UPF2->UE2's satellite base station 2->UE2. This path includes two segments of satellite-to-ground communication, specifically: 1) UE1->UE1's satellite base station 1; 2) UE2's satellite base station 2->UE2.

[0111] like Figure 3 As shown, after the UPF is deployed to a satellite, to reduce the complexity of inter-satellite routing, an Nx tunnel can be established between the satellite UPFs of UE1 and UE2 for direct communication between them. This tunnel is used to forward data between the satellites of UE1 and UE2, so the UE's IP address is not exposed on the inter-satellite link interface. The underlying routing module of the inter-satellite link only sees the IP address of the satellite UPF and not the IP address of the UE. Figure 3 As can be seen, an Nx interface has been added between satellite UPF1 and satellite UPF2, that is, an Nx tunnel has been established between satellite UPF1 and satellite UPF2. For example, the Nx tunnel can be an N19 tunnel, or a GPRS Tunneling Protocol User Plane (GTP-U) tunnel. Here, GPRS refers to General Packet Radio Service.

[0112] exist Figure 3 In this configuration, to reduce latency, the base station and UPF serving the UE can be located on the same satellite. Therefore, UPF1 and base station 1 are on the same satellite, and UPF2 and base station 2 are on the same satellite. An Nx tunnel is established between UPF1 and UPF2 so that when UPF1 and UPF2 forward data packets for communication between UE1 and UE2, they do not need to handle routing based on the UE's IP address, reducing the complexity of inter-satellite routing. UE1's UPF1 and UE2's UPF2 can be controlled by different SMFs or they can be controlled by the same SMF. Figure 3 The diagram shows the case where UPF1 and UPF2 are controlled by different SMFs.

[0113] When base stations and UPFs are deployed on satellites, satellite handover will occur even if the UE remains stationary on the ground, because satellites orbit the Earth at fixed frequencies and move very quickly in low Earth orbit. In this architecture, satellite handover means that both the base station and the UPF serving the UE change simultaneously. Therefore, when the UE switches base stations, the UPF also needs to switch accordingly.

[0114] In one possible implementation, after the source base station determines that UE1 needs to hand over to the target base station 1, each network element begins to prepare for the handover of UE1. For example, during this process, the ground-based SMF will frequently interact with network elements on the satellite (such as the target base station 1 and the target UPF1) to configure the context of UE1's PDU session in the target base station 1 and the target UPF1. The large amount of ground-to-ground communication results in a large delay in the handover process of UE1.

[0115] To address the aforementioned issues, this application provides a solution that pre-emptively prepares for the handover of UE1 when it is anticipated that UE1 will undergo a handover in the future (e.g., configuring a PDU session context for UE1's PDU session on the target base station 1 and target UPF 1). This allows UE1 to utilize the pre-configured information during the subsequent handover process, thereby reducing the signaling overhead of ground-to-ground communication during the handover and thus lowering the handover latency. The configuration of the PDU session context mentioned in this application can be understood as establishing a user plane connection between the base station and the UPF for the PDU session. The solution provided by this application will be further described below with reference to the accompanying drawings.

[0116] Based on the above, Figure 4a An exemplary schematic diagram of a possible satellite handover method provided in an embodiment of this application is shown. Figure 4a The illustrated scheme is described from the perspective of the interaction between the first communication device and the second communication device. The first communication device can be a source base station 1 or an AMF, or it can be a device or chip internal to the source base station 1 or the AMF. The second communication device can be an SMF or a target base station 1, or it can be a device or chip internal to the SMF or the target base station 1.

[0117] It should be noted that in this embodiment, UE1 may have one or more PDU sessions. This embodiment uses one PDU session of UE1 as an example for description. The execution process of other PDU sessions of UE1 is similar and will not be repeated. In this embodiment, the PDU session of UE1 will be switched. The source UPF1 and source base station1 that provide services for the PDU session before the switch are deployed on the same satellite (e.g., the first satellite). In this case, when the base station of the PDU session of UE1 is switched, the UPF that provides services for the PDU session also needs to be switched.

[0118] Figure 4a In the example, UE1's satellite undergoes a handover. Before the handover, UE1 is served by source base station 1 and source UPF1 on the first satellite. After the handover, UE1 is served by target base station 1 and target UPF1 on the second satellite. UE2's satellite does not undergo a handover; UE2 is served by base station 2 and UPF2 on the third satellite. Alternatively, it can be understood that UE2 completed the handover before UE1's handover, and UE2 is served by base station 2 and UPF2 on the third satellite after the handover.

[0119] like Figure 4a As shown, the method includes the following steps:

[0120] Step 401: The first communication device estimates that UE1 will switch from source base station 1 to target base station 1 at a future time.

[0121] In the embodiments of this application, the first communication device "estimates" that UE1 will switch from source base station 1 to target base station 1 at a future time. This means that the first communication device estimates in advance whether UE1 will switch from source base station 1 to target base station 1 in the future. "Estimate" can also be replaced with other words, such as "determine", "predetermine", "pre-determine", "pre-estimate", "predict", "pre-speculate", etc.

[0122] Step 402: The first communication device sends a first request message.

[0123] Correspondingly, the second communication device receives the first request message.

[0124] In this application embodiment, the first request message has two implementation methods. In one implementation method, the first request message indicates that UE1 is expected to be switched at a future time.

[0125] For example, the first request message may include indication information to indicate that UE1 is expected to be switched at a future time.

[0126] For example, the first request message may not include the "indication information for indicating that UE1 is expected to be switched at a future time", but the first request message has the function of indicating that UE1 is expected to be switched at a future time.

[0127] For example, if the first request message is sent from the source base station to the destination base station 1, and the first request message is a pre-handover request message, then the first request message has the ability to instruct UE1 to hand over to the target base station 1. The destination base station 1 can determine that UE1 will hand over to the target base station 1 at a future time based on the received first request message.

[0128] In another possible implementation, the first request message indicates that UE1's PDU session is expected to be switched at a future time.

[0129] For example, the first request message may include pre-handover indication information indicating that UE1's PDU session is expected to be switched at a future time.

[0130] For example, the first request message may not include the pre-switching indication information, but the first request message has the function of indication.

[0131] Step 403: The second communication device prepares for the handover of UE1.

[0132] The method flow provided in this application embodiment can be divided into two parts: the first part can be called the pre-switching process, and the second part can be called the switching process. Figure 4a The method shown belongs to the pre-handover process. Compared with the scheme of performing a series of preparatory work in the handover process, the pre-handover process in this embodiment can do some preparatory work for the handover of UE1 in advance (such as establishing the PDU session context for UE1), thereby reducing the signaling interaction in the subsequent handover process, especially the signaling interaction between air and ground, thereby reducing the latency of the subsequent handover process.

[0133] In this embodiment of the application, in step 401, the first communication device can estimate the UE1's switch from the source base station 1 to the target base station 1 at a future time through the following possible implementation a1 or implementation a2.

[0134] In implementation method a1, the first communication device estimates, based on the location information of UE1 and the motion trajectory of the first satellite, that UE1 will switch from source base station 1 to target base station 1 at a future time.

[0135] In this embodiment, the satellites (such as the first satellite, the second satellite, the fourth satellite, and the third satellite) are in motion. The satellites may move in a regular pattern. For example, the first communication device can determine the satellite's trajectory based on information such as ephemeris (an ephemeris table, almanac, etc., used to locate the position of celestial bodies at any given time). It can also estimate the satellite's position at a certain moment based on ephemeris information. Of course, the satellite's trajectory or position information can also be transmitted to the first communication device from other devices. In this embodiment, the satellite's trajectory can be understood as simple trajectory information, simple position information at a certain moment, or a combination of both.

[0136] In implementation method a1, in one possible implementation, UE1 is located within the signal coverage area of ​​the first satellite at a first moment (in this embodiment, the first moment can also be understood as the current moment). Based on the location information of UE1 and the motion trajectory information of the first satellite, the first communication device estimates that UE1 will switch from the source base station 1 to the target base station 1 at a second moment, provided that UE1 is estimated to be within the signal coverage area of ​​the second satellite at a second moment. The second moment is a future moment later than the first moment.

[0137] In this embodiment of the application, the first communication device may also estimate whether UE1 will switch from source base station 1 to target base station 1 at a future time through the following possible implementation methods a1-1 and a1-2.

[0138] Implementation method a1-1:

[0139] Since the satellite is in motion, and the movement speed of UE1 is relatively slow and negligible compared to the satellite, in one possible implementation, the first communication device can predict whether UE1 will switch from source base station 1 to target base station 1 at a future time based on the position information of UE1 at the first moment and the movement trajectory of the first satellite.

[0140] For example, if UE1 is located at position 1 at the first moment, and position 1 is within the signal coverage area of ​​the first satellite at the first moment, and the first communication device estimates that UE1's position 1 (or a position near position 1) is within the signal coverage area of ​​the second satellite at the second moment, then the first communication device estimates that UE1 will switch from the source base station 1 to the target base station 1 at the second moment.

[0141] Since the location information of UE1 at the current time can be used to estimate whether UE1 will switch from source base station 1 to target base station 1 at the second time, the complexity of the scheme can be reduced. The location information of UE1 at the first time can be provided to the first communication device by UE1 or other devices.

[0142] Implementation method a1-2:

[0143] In another possible implementation, the first communication device can infer the location 2 of UE1 at the second moment based on the motion trajectory information of UE1 over a period of time. If the first communication device predicts that the location 2 of UE1 at the second moment is within the signal coverage area of ​​the second satellite, it estimates that UE1 will switch from the source base station 1 to the target base station 1 at the second moment.

[0144] Since the position of UE1 at the second moment can be estimated based on the movement trajectory of UE1, and then the position of UE1 at the second moment can be combined to estimate whether UE1 has switched from source base station 1 to target base station 1 at the second moment, the accuracy of the prediction results can be improved.

[0145] In this embodiment, the position of UE1 at the second moment can also be determined by the movement pattern information of UE1 over a period of time. For example, the position of UE1 at the second moment can be predicted based on the expected behavior of UE1, that is, the movement pattern of UE1 at different times. The position 2 information of UE1 at the second moment can be predicted by the first communication device, or it can be predicted by other devices and then sent to the first communication device.

[0146] In one possible implementation of this application, UE1's location at the first moment is not within the coverage area of ​​the second satellite. Alternatively, UE1 does not meet the base station handover conditions at the first moment. This allows for advance preparation for UE1's subsequent handover. The base station handover conditions in this application can be conditions requiring UE1 to handover to another satellite. For example, when UE1 meets the base station handover conditions, the source base station determines that UE1 needs to handover to target base station 1 on the second satellite, at which point the handover process for UE1 needs to be initiated.

[0147] As can be seen, the solution provided in this application can predict in advance whether UE1 will switch to target base station 1 in the future, rather than preparing only when it is detected that UE1 needs to switch to target base station 1 (e.g., UE1 meets the base station handover conditions). In other words, there is a certain time difference between the first and second moments. Thus, some of the content that originally needed to be executed in the handover process of UE1 can be executed in advance (e.g., N3 tunnel information can be configured for UE1 in advance at target base station 1 and target UPF1), thereby reducing the amount of signaling that needs to be executed in the handover process of UE1, and thus reducing the latency of the handover process of UE1.

[0148] In another possible implementation, the time difference between the second moment and the first moment can be equal to a preset time difference threshold. For example, if the time difference threshold is 5 minutes, the first communication device sends a first request message if it estimates that UE1 will switch from source base station 1 to target base station 1 in 5 minutes. However, if the first communication device estimates that UE1 will switch from source base station 1 to target base station 1 in more than 5 minutes (e.g., 1 hour), it will not send the first request message until it estimates that UE1 will switch from source base station 1 to target base station 1 in 5 minutes. Since estimating the next handover of UE1 too early can easily lead to inaccurate predictions due to the long lead time, setting a time difference threshold can improve the accuracy of estimating the handover of UE1.

[0149] It should be noted that the first communication device may simultaneously determine that multiple terminal devices will switch to other satellites after 5 minutes. In this case, the first communication device can send the first request messages corresponding to these multiple terminal devices all at once; or it can send them in batches, such as sending the first request messages corresponding to one or more of the multiple terminal devices at once. For the processing flow of the first communication device for one of the multiple terminal devices, please refer to the relevant content of UE1, which will not be repeated here.

[0150] In implementation method a2, the first communication device can estimate, based on messages sent by other devices, whether UE1 will switch from the source access network device to the first target access network device at a future time.

[0151] For example, the first communication device can receive a second request message and, based on the received second request message, estimate that UE1 will switch from the source access network device to the first target access network device at a future time. The second request message indicates that UE1 is estimated to switch from the source base station 1 to the target base station 1 at a future time.

[0152] In other words, in implementation method a2, other devices can predict whether UE1 will switch from source base station 1 to target base station 1. When other devices predict that UE1 will switch from source base station 1 to target base station 1 at a future time, they send a second request message to the first communication device.

[0153] In this application embodiment, the second request message indicating that UE1 is expected to switch from source base station 1 to target base station 1 at a future time can be implemented in various ways. For example, the second request message may include indication information indicating that UE1 is expected to switch from source base station 1 to target base station 1 at a future time.

[0154] For example, the second request message may not include the indication information; instead, the second request message has an indicative function. For instance, if the second request message is sent from the destination base station 1 to the first communication device, and the second request message indicates that UE1 will switch at a future time, then since the second request message comes from the destination base station 1, the first communication device can determine that UE1 will switch to the destination base station 1 at a future time. Furthermore, since the first communication device knows in advance that UE1 was originally served by the source base station 1, the first communication device can predict, based on the second request message, that UE1 will switch from the source base station 1 to the destination base station 1 at a future time.

[0155] Figure 4a The first and second communication devices shown can be implemented in various ways, and several examples are described below.

[0156] Figure 4b An exemplary embodiment illustrates the process entity of yet another possible satellite handover method, in Figure 4b In the scheme shown, the first communication device is AMF and the second communication device is SMF.

[0157] like Figure 4b As shown, the method includes:

[0158] Step 411: AMF sends the first request message to SMF.

[0159] Correspondingly, SMF receives the first request message.

[0160] Step 412, SMF sends a fifth request message to target UPF1.

[0161] Correspondingly, the target UPF1 receives the fifth request message.

[0162] The fifth request message requests the establishment of the context of the PDU session in the target UPF1. In this embodiment, the context of the PDU session can be understood as the N4 session context of the PDU session.

[0163] There are several ways for the SMF to send the fifth request message in step 412. For example, the SMF can send the fifth request message directly to the target UPF1. Alternatively, the SMF can transmit the fifth request message to the target UPF1 through other devices.

[0164] Step 413: Target UPF1 configures the PDU session context for UE1.

[0165] Step 414: Target UPF1 sends the fifth response message to SMF.

[0166] SMF receives the fifth response message from target UPF1.

[0167] The fifth response message indicates that the target UPF1 has configured the context of the PDU session.

[0168] Step 415: SMF triggers target base station 1 to configure the PDU session context for UE1 via AMF.

[0169] In one possible implementation, target base station 1 also needs to know the CN N3 tunnel information in the context of target UPF1 configuring the PDU session for UE1, and target UPF1 also needs to know the ANN3 tunnel information in the context of target base station 1 configuring the PDU session for UE1, thereby enabling communication between target base station 1 and target UPF1. There are various possible methods for obtaining this information; for example, SMF can send CN N3 tunnel information to target base station 1, and SMF can send ANN3 tunnel information to target UPF1. Specific transmission methods will be discussed later and will not be elaborated upon here.

[0170] Step 416: The SMF returns a first response message to the AMF, indicating that the pre-handover of UE1 has been completed.

[0171] If the target base station 1 needs to switch base stations and switches to target base station 1, it indicates that the first communication device's prediction was correct. In this case, the switching process shown in steps 417 to 420 can be executed:

[0172] Step 417: Target base station 1 receives a message from UE1 indicating that RRC reconfiguration is complete.

[0173] Step 418: Target base station 1 sends a first path handover request message to AMF.

[0174] Correspondingly, the AMF receives the first path handover request message from the target base station 1.

[0175] In one possible implementation, if the target base station 1 determines that the pre-handover of UE1 has been completed, it can indicate that the first terminal device has been switched via a first path handover request message. In another possible implementation, the first path handover request message can also indicate that the PDU session has been switched (the PDU session being switched can be understood as the user plane path after the PDU session has been established), so that other devices do not need to perform preparatory work for the handover of UE1.

[0176] In this embodiment of the application, establishing a user plane path may include the target base station 1 configuring a PDU session context for UE1, the target UPF1 configuring a PDU session context for UE1, the target base station 1 obtaining the CN N3 tunnel information in the PDU session context configured by the target UPF1 for UE1, and the target UPF1 obtaining the AN N3 tunnel information in the PDU session context configured by the target base station 1 for UE1, etc.

[0177] Step 419: AMF sends a third request message to SMF.

[0178] Correspondingly, the SMF receives a third request message from the AMF.

[0179] In one possible implementation, the third request message indicates that the PDU session has been switched (the PDU session being switched can be understood as the user plane path after the PDU session switch has been established). In this way, the SMF can determine that UE1 has completed the pre-switching and can directly return the third response message.

[0180] In another possible implementation, the third request message does not indicate that the PDU session has been switched, but rather that the PDU session is pending a switch (which can be understood as the third request message also indicating that the PDU session user plane path is pending establishment). In this case, the SMF can determine again whether the pre-switching for UE1 has been completed (e.g., whether the user plane path of the PDU session has been established). If it has been completed, the SMF can directly return the third response message.

[0181] Step 420: SMF sends a third response message to AMF.

[0182] Correspondingly, the AMF receives a third response message from the SMF. The third response message indicates that the PDU session context update is complete.

[0183] If the target base station 1 needs to switch base stations and switches to target base station 2, it indicates that the first communication device prediction failed. In this case, the switching process shown in steps 421 to 427 can be executed:

[0184] Step 421, the target base station 2 receives a message from UE1 indicating that the RRC reconfiguration is complete.

[0185] Step 422: Target base station 2 sends a second path handover request message to AMF.

[0186] Correspondingly, the AMF receives a second path handover request message from the target base station 2.

[0187] The second path switching request message may contain PDU session information for the user plane path to be established.

[0188] Step 423: AMF sends a fourth request message to SMF.

[0189] Correspondingly, the SMF receives the fourth request message from the AMF.

[0190] The fourth request message indicates that the PDU session is pending handover (the PDU session pending handover can be understood as the user plane path after the PDU session handover is pending establishment).

[0191] Step 424, SMF sends a sixth request message to the target UPF2.

[0192] Correspondingly, the target UPF2 receives the sixth request message. The sixth request message requests the configuration of the PDU session context on the target UPF2.

[0193] Step 425: Configure the PDU session context of UE1 for target UPF2.

[0194] Step 426: Target UPF2 receives the sixth response message from SMF.

[0195] Correspondingly, the SMF receives the sixth response message from the target UPF2.

[0196] Step 427: The SMF triggers the target base station 2 to configure the PDU session context for UE1 via the AMF.

[0197] In one possible implementation, target base station 1 also needs to know the CN N3 tunnel information in the context of target UPF1 configuring the PDU session for UE1, and target UPF1 also needs to know the ANN3 tunnel information in the context of target base station 1 configuring the PDU session for UE1, thereby enabling communication between target base station 1 and target UPF1. There are various possible methods for obtaining this information; for example, SMF can send CN N3 tunnel information to target base station 1, and SMF can send ANN3 tunnel information to target UPF1. Specific transmission methods will be discussed later and will not be elaborated upon here.

[0198] In step 428, the SMF returns a fourth response message to the AMF, indicating that the handover of UE1 has been completed.

[0199] As can be seen from the above, in practical applications, prediction errors may occur. For example, in the pre-handover process, the first communication device predicts that UE1 will soon hand over to target base station 1 on the second satellite. However, during the handover process, due to certain reasons (such as satellite movement or UE1 movement), UE1 needs to hand over to target base station 2 deployed on the fourth satellite. In this case, the SMF still needs to reconfigure the context for UE1's PDU session during the handover process. When the prediction fails, the source base station needs to use target base station 2 deployed on the fourth satellite as the new target base station and the UPF deployed on the fourth satellite as the new target UPF (this new target UPF can be called target UPF2) to execute the handover process. The handover process scheme in this case can be found in the aforementioned section. Figure 3 The scheme shown is similar and will not be described in detail again. It is worth noting that when the prediction fails, the Session Management Context Update Request message sent by the AMF to the SMF can indicate that the PDU session of UE1 is pending handover (the PDU session pending handover can be understood as the user plane path after the PDU session handover is pending establishment).

[0200] Figure 4c An exemplary embodiment illustrates the process entity of yet another possible satellite handover method, in Figure 4b In the scheme shown, the first communication device is the source base station 1, and the second communication device is the target base station 1.

[0201] like Figure 4b As shown, the method includes:

[0202] Step 431: Source base station 1 sends a first request message to target base station 1.

[0203] Correspondingly, target base station 1 receives the first request message.

[0204] Step 432: Target base station 1 configures the context of the PDU session for UE1.

[0205] Step 433: Target base station 1 sends a seventh request message to AMF.

[0206] Correspondingly, the target UPF1 receives the fifth request message.

[0207] The seventh request message includes information about the tunnel configured by the first target access network device for the PDU session; the seventh request message indicates that UE1 is expected to be switched at a future time.

[0208] Step 434: AMF sends the eighth request message to SMF.

[0209] Correspondingly, the SMF receives the AMF's eighth request message. The eighth request message includes information about the tunnel configured by the first target access network device for the PDU session, and indicates that UE1's PDU session is expected to be switched at a future time.

[0210] Step 435: SMF triggers target UPF1 to configure the PDU session context for UE1.

[0211] Step 436: SMF returns the eighth response message to AMF.

[0212] Correspondingly, the AMF receives the eighth response message. The eighth response message indicates that the pre-handover of UE1 has been completed.

[0213] Step 437, AMF sends the seventh response message to target base station 1.

[0214] Correspondingly, target base station 1 receives the seventh response message. The seventh response message indicates that the pre-handover of UE1 has been completed.

[0215] Step 438: Target base station 1 sends a first response message to source base station 1.

[0216] Correspondingly, source base station 1 receives the first response message.

[0217] In one possible implementation, the first response message also includes Radio Access Control (RRC) configuration information required for UE1 to access the first target access network device. Thus, the first target access network device can send the required RRC configuration information to the source access network device during the pre-handover phase, thereby saving the signaling costs incurred in obtaining this RRC configuration information during the handover process, and further reducing the handover latency.

[0218] If the target base station 1 needs to switch base stations and switches to the target base station 1, it means that the first communication device's prediction is correct. In this case, the switching process shown in steps 417 to 420 can be executed.

[0219] If the target base station 1 needs to switch base stations and switches to target base station 2, it indicates that the first communication device prediction failed. In this case, the switching process shown in steps 421 to 427 can be executed.

[0220] As can be seen from the above, when the second communication device is target base station 1, target base station 1 can perform some preparatory work for the handover of UE1 based on the first request, such as triggering the process of creating a context for one or more PDU sessions of UE1. For example... Figure 4c As shown, target base station 1 sends a seventh request message to the AMF, indicating that UE1 is expected to be handed over at a future time. The message contains PDU session information that will be handed over with UE1. Another example is that target base station 1 sends a pre-handover request message to target UPF1, which also contains PDU session information that will be handed over with UE1. Details of this example can be found in the subsequent description and will not be elaborated upon here.

[0221] Based on the above, Figure 5 This paper exemplarily illustrates a schematic flowchart of another satellite handover method provided in an embodiment of this application. Figure 5 The following example illustrates the use of AMF as the first communication device and SMF as the second communication device. Figure 5 The scheme shown includes a pre-switching process and a switching process, wherein Figure 5 The pre-handover process of UE1 is illustrated using steps 501 to 505, and the handover process of UE1 is illustrated using steps 506 to 522.

[0222] like Figure 5 As shown, the method includes:

[0223] Step 501: AMF predicts that UE1 will switch from source base station 1 to target base station 1 at a future time.

[0224] For details regarding step 501, please refer to the aforementioned text. Figure 4a The details of step 401 will not be repeated here.

[0225] Step 502, AMF sends a first request message to SMF ( Figure 5 (The first request message is illustrated as session management context update request message b0).

[0226] Correspondingly, SMF receives Session Management Context Update Request message b0.

[0227] The Session Management Context Update Request message b0 indicates that UE1's PDU session is expected to be switched at a future time.

[0228] Optionally, the Session Management Context Update Request message b0 can be an Nsmf_PDUSession_SMContextUpdate Request message.

[0229] It should be noted that UE1 may have multiple PDU sessions, which may be managed by multiple SMFs or by a single SMF; this embodiment does not impose such limitations. In this embodiment, the AMF can send a first request message to the SMF corresponding to each PDU session to which a handover will occur. This embodiment uses one PDU session as an example for illustrative purposes; the handover process for other PDU sessions is similar and will not be described in detail here.

[0230] In one possible implementation, the first request message includes at least one of the following: information about target base station 1 (e.g., identification information of target base station 1), information about target UPF1 (e.g., identification information of target UPF1), or information about the second satellite (e.g., identification of the second satellite). Target UPF1 and target base station 1 are deployed on the second satellite.

[0231] When the first request message includes information about the target base station 1, the SMF can select a UPF that is deployed on the same satellite as the target base station 1 as the target UPF1.

[0232] When the first request message includes information about the second satellite, the SMF can select the UPF deployed on the second satellite as the target UPF1.

[0233] When the first request message includes information about the target UPF1, the SMF can determine the target UPF1 based on the first request message.

[0234] Step 503a: The SMF selects the target UPF1, which is deployed on the same satellite as the target base station 1, as the new UPF of UE1, and sends a session management context update response message b1 to the AMF.

[0235] Accordingly, the AMF receives the session management context update response message b1.

[0236] In one possible implementation, the SMF can allocate N3 tunnel information for a PDU session to the target UPF1 and send the allocated N3 tunnel information to the target UPF1. The tunnel information can be included in a rule sent to the target UPF1. In this embodiment, the N3 tunnel of the target UPF1 can also be referred to as the core network (CN) N3 tunnel.

[0237] In one possible implementation, the session management context update response message b1 may include N2 session management information. In this embodiment, the N2 session management information can be transparently transmitted from the AMF to the target base station 1. When the SMF allocates CN N3 tunnel information to the target UPF1, the N2 session management information may also include CN N3 tunnel information. Thus, after the AMF transparently transmits the N2 session management information to the target base station 1 through step 503b, the target base station 1 can obtain the CN N3 tunnel information from the N2 session management information.

[0238] In one possible implementation, the N2 session management information may further include an N4 container, which may contain an N4 session establishment request message. The fifth request message sent by the SMF to the target UPF1 mentioned in this application embodiment may be an N4 session establishment request message. This N4 session establishment request message is a message that the SMF needs to send to the target UPF1, and the AMF and target base station 1 can transparently transmit this N4 container. In one possible implementation, the N4 session establishment request message includes rules for CNN3 tunnel information.

[0239] When SMF allocates Nx tunnel information to target UPF1, the N4 session establishment request message in session management context update response message b1 can also contain the rules for allocating Nx tunnel information to target UPF1.

[0240] In another possible implementation, the N4 session establishment request message in the session management context update response message b1 may also include Nx tunnel information of UPF2, so that target UPF1 and UPF2 can communicate based on the Nx tunnel information of target UPF1 and the Nx tunnel information of UPF2.

[0241] Optionally, if UE2 has undergone pre-handover but not yet actual handover (i.e., UE2 performed the pre-handover procedure before UE1, but has not yet performed the handover procedure), then the Nx tunnel information of UPF2 can be the Nx tunnel information of the UPF that will serve UE2 after the handover (which can be called the target UPF2 of UE2). In another possible implementation, since UE2 has undergone pre-handover but not yet actual handover, the SMF can send the Nx tunnel information of the UPF currently serving UE2, as well as the Nx tunnel information of the UPF that is estimated to serve UE2 during the pre-handover process, to the target UPF1.

[0242] If UE2 has not undergone pre-handover, the Nx tunnel information of UPF2 can be the Nx tunnel information of the UPF currently serving UE2. Optionally, if UE2 has completed the handover process, the Nx tunnel information of UPF2 can be the Nx tunnel information of the UPF currently serving UE2 (i.e., the UPF that provides services to UE2 after the handover).

[0243] Step 503b: AMF sends a pre-handover request message b2 to target base station 1.

[0244] Correspondingly, target base station 1 receives a pre-handover request message b2 from AMF.

[0245] In one possible implementation, in step 503b, the pre-handover request message b2 sent by the AMF to the target base station 1 includes the N2 session management information carried in the session management context update response message b1 mentioned above.

[0246] Step 503c: Target base station 1 sends a pre-handover request message b3 to target UPF1.

[0247] Correspondingly, target UPF1 receives pre-handover request message b3 from target base station 1.

[0248] In one possible implementation, target base station 1 can configure a context for UE1's PDU session, such as allocating a CN N3 tunnel for UE1. The N3 tunnel on the target base station 1 side in this embodiment can also be referred to as an access network (AN) N3 tunnel. The AN N3 tunnel information and CN N3 tunnel information in this embodiment can be used for communication between target base station 1 and target UPF1.

[0249] In one possible implementation, the pre-switching request message b3 may carry AN N3 tunnel information. The pre-switching request message b3 may also include the N4 container from the session management context update response message b1 described above.

[0250] In step 503d, target UPF1 sends a pre-handover response message b4 to target base station 1.

[0251] Correspondingly, target base station 1 receives pre-handover response message b4 from target UPF1.

[0252] The pre-switching response message b4 can instruct the target UPF1 to complete the pre-switching.

[0253] The pre-handover response message b4 may contain an N4 container, which contains an N4 session establishment response message. The pre-handover response message is sent from target UPF1 to target base station 1, while the N4 container is sent from target UPF1 to SMF. The N4 session establishment response message may be an example of the fifth response message mentioned in the embodiments of this application.

[0254] In one possible implementation, the N4 session establishment response message may include AN N3 tunnel information.

[0255] Step 503e: Target base station 1 sends a pre-handover response message b5 to AMF.

[0256] Correspondingly, the AMF receives a pre-handover response message b5 from the target base station 1.

[0257] The pre-handover response message b5 can instruct the target base station 1 to complete the pre-handover.

[0258] In one possible implementation, the pre-switching response message b5 may include N2 session management information, which may include the N4 container included in the pre-switching response message b4 in step 503d, and the N4 container includes the N4 session establishment response message.

[0259] In one possible implementation, the rule includes AN N3 tunnel information in the N4 session establishment response message. The N2 session management information may not include AN N3 tunnel information.

[0260] In another possible implementation, the N4 session establishment response message does not include rules containing AN N3 tunnel information. The N2 session management information may include rules containing AN N3 tunnel information.

[0261] Step 503f: AMF sends a Session Management Context Update Request message b6 to SMF.

[0262] Correspondingly, the SMF receives a Session Management Context Update Request message b6 from the AMF.

[0263] The Session Management Context Update Request message b6 can instruct the PDU session to complete the pre-switch.

[0264] In one possible implementation, the session management context update request message b6 contains N2 session management information, which may include an N4 container included in the pre-switch response message b4, the N4 container including an N4 session establishment response message.

[0265] Step 504: SMF sends Session Management Context Update Response Message b7 to AMF.

[0266] Correspondingly, the AMF receives a Session Management Context Update Response Message b7 from the SMF. The Session Management Context Update Response Message b7 can be used to indicate that the context update of UE1's PDU session is complete. The Session Management Context Update Response Message b7 can be an example of the first response message mentioned in the embodiments of this application.

[0267] It should be noted that steps 503a to 503f above are described using the example of SMF allocating CN N3 tunnel information to UPF1. In another possible implementation, CN N3 tunnel and / or Nx tunnel can be allocated by the target UPF1. Figure 5 The differences in the examples shown are:

[0268] When target UPF1 allocates CN N3 and Nx tunnels, the N4 container in the session management context update request response message in step 503a above no longer carries CN N3 and Nx tunnel information. After receiving the pre-switching request message b2, target UPF1 can allocate CN N3 and Nx tunnels and carry the CN N3 and Nx tunnel information in the N4 response message in the pre-switching response message b4.

[0269] The rules for transmitting information including AN3 tunnel information can be found above. Figure 5 The content shown will not be repeated here.

[0270] Step 505, SMF sends N4 session update request message b8 to UPF2.

[0271] Step 505 is optional. It can be executed during the pre-switching process or during the subsequent switching process.

[0272] The N4 session update request message b8 in step 505 carries the Nx tunnel information on the target UPF1 side, so that after UE1 completes the handover, UE2 can communicate with UE1 through UPF2 and the target UPF1.

[0273] Step 506: Source base station 1 determines that UE1 needs to switch to target base station 1.

[0274] In step 506, the source base station can determine whether UE1 needs to be handed over to the target base station 1 in various ways, which are not limited in this application. For example, the source base station can determine whether UE1 meets the handover conditions based on the measurement report provided by UE1, thereby determining that UE1 needs to be handed over to the target base station 1.

[0275] Step 507: Source base station 1 sends a handover request message to target base station 1.

[0276] Accordingly, target base station 1 receives the handover request message.

[0277] Step 508: Target base station 1 sends a handover response message to source base station 1.

[0278] Correspondingly, source base station 1 receives the handover response message.

[0279] The handover response message may include a transparent container sent by the target base station 1 to UE1, and the transparent container contains an RRC reconfiguration message.

[0280] Step 509: Source base station 1 sends an RRC reconfiguration message to UE1.

[0281] Accordingly, UE1 receives the RRC reconfiguration message.

[0282] This RRC reconfiguration request message is an RRC reconfiguration message sent by target base station 1 to UE1.

[0283] Step 510: UE1 synchronizes with target base station 1.

[0284] Step 511, UE1 sends an RRC reconfiguration complete message to target base station 1.

[0285] Accordingly, target base station 1 receives the RRC reconfiguration complete message.

[0286] Step 512: Target base station 1 sends a path switching request message to AMF.

[0287] Accordingly, the AMF receives the path switching request message.

[0288] In the first implementation, the path switching request message indicates that UE1's PDU session has been switched (PDU session switching can be understood as the user plane path after the PDU session switching has been established). In this case, the first path switching request message mentioned in the embodiments of this application can be the path switching request message in step 512.

[0289] For example, an indication message can be added to the path handover request message sent by target base station 1 to indicate that UE1's PDU session has been switched. In this case, the path handover request message sent by target base station 1 can reuse the path handover request message defined in the current standard, and can carry the indication message indicating that the PDU session has been switched in the old information elements or other new information elements of the path handover request message.

[0290] For example, target base station 1 can define a new path switching request message. This path switching request message itself has the meaning of indicating UE1's PDU session, and there is no need to add indication information to this path switching request message to indicate that UE1's PDU session has been switched.

[0291] In the second implementation method, the path switching request message indicates that UE1 has switched.

[0292] In the second implementation method, the target base station 1 may not need to add additional indication information indicating that the PDU session has been switched in the path switching request message. Instead, it can reuse the path switching request message in the current standard, and let the subsequent AMF or SMF determine whether a switching configuration context for the PDU session is required.

[0293] In one possible implementation of embodiments one and two, the target base station 1 may also send a list of PDU sessions with established user plane paths to the AMF, indicating that the user plane paths of the PDU sessions in the PDU session list have been established. This PDU session list may be carried in the path handover request message.

[0294] For example, the first path switching request message may carry a list of active user plane PDU sessions, where the PDU sessions in the list are those for which user plane paths have been established. In this case, if the first communication device determines that a PDU session is included in the list of active user plane PDU sessions, it can determine that the user plane path for that PDU session after the switch has been established.

[0295] For example, the first path switching request message may carry a list of PDU sessions to be activated in the user plane, where the PDU sessions in the list are those for which the user plane path has not yet been established. In this case, if the first communication device determines that a PDU session is not included in the list of PDU sessions to be activated in the user plane, it can assume that the user plane path for that PDU session has been established after the switch. In this application, the establishment of the user plane path can be understood as the user plane being activated.

[0296] In this way, other network elements or devices no longer need to determine whether a context has been configured for the handover of UE1's PDU session. Based on the PDU session list in step 512, it can be determined that UE1 has successfully switched to the first target access network device and the relevant user plane path has been established. That is, the SMF no longer needs to interact with the UPF or base station to establish the user plane.

[0297] Step 513, AMF sends Session Management Context Update Request message b9 to SMF.

[0298] Accordingly, SMF receives the Session Management Context Update Request message b9.

[0299] The Session Management Context Update Request message b9 is used to notify the SMF that the PDU session has been switched. This Session Management Context Update Request message b9 can be an example of the third request message mentioned in the embodiments of this application.

[0300] In one possible implementation, if the path switching request message in step 512 indicates that the PDU session of UE1 has been switched (which can be understood as the user plane path after the switch of the PDU session has been established), the session management context update request message b9 sent by the AMF in step 513 can carry indication information indicating that the PDU session of UE1 has been switched. In this way, if the SMF receives the indication information, it will not need to trigger other devices to configure the context for the PDU session.

[0301] In another possible implementation, the path switching request message in step 512 reuses the existing path switching request message. If the AMF determines that the relevant context has been configured for the migration of UE1's PDU session to the target base station 1 (i.e., the pre-switching process has been completed), the session management context update request message b9 sent by the AMF in step 513 can carry indication information indicating that UE1's PDU session has been switched. In this way, if the SMF receives the indication information, it will not need to trigger other devices to configure the context for the PDU session.

[0302] In another possible implementation, the path switching request message in step 512 reuses an existing path switching request message, and the session management context update request message b9 sent by the AMF in step 513 can reuse the session management context update request message defined in the existing standard. After receiving the message, the SMF can determine on its own whether it needs to trigger other devices to configure the context for the PDU session.

[0303] Step 514: The SMF sends a Session Management Context Update Response Message b10 to the AMF. The AMF then receives the Session Management Context Update Response Message b10.

[0304] In one possible implementation, if the Session Management Context Update Request message b9 received by the SMF in step 513 indicates that the PDU session of UE1 has been switched (which can be understood as the user plane path after the switch of the PDU session has been established), the SMF does not need to determine whether it is necessary to trigger other devices to configure the context for the PDU session.

[0305] In another possible implementation, if the Session Management Context Update Request message b9 received by the SMF in step 513 indicates that UE1's PDU session is pending handover (PDU session handover can be understood as the user plane path after the PDU session handover is pending establishment), then the SMF can determine on its own whether it needs to trigger other devices to configure context for the PDU session after receiving this indication information. If the SMF determines that the relevant context has already been configured for UE1's PDU session to migrate to the target base station 1 (or target UPF1) (i.e., the pre-handover process has been completed), then the SMF determines that it is not necessary to trigger other devices to configure context for the PDU session.

[0306] Step 515: AMF sends a path switching response message to target base station 1.

[0307] Accordingly, target base station 1 receives the path handover response message.

[0308] As can be seen from the above, because the pre-handover procedure was executed in advance, it was predicted that UE1's PDU session would switch to target base station 1 at a future time. Therefore, some preparatory work was done in advance for this handover, such as creating the context of UE1's PDU session on target base station 1 and target UPF1. Then, when UE1 actually initiates the handover procedure, if UE1 switches to target base station 1 in the handover procedure, it means that the prediction was correct. In this way, it is not necessary to create the context of UE1's PDU session again in the handover procedure, but to use the context configured in the pre-handover procedure. This can reduce the number of signaling interactions in the handover procedure, especially the number of signaling interactions between SMF and target base station 1 and target UPF1 deployed on the satellite, thereby reducing the latency of the handover procedure. The beneficial effects brought by this embodiment are even more obvious when a large number of terminal devices execute the handover procedure at the same time.

[0309] based on Figure 5 The content shown, Figure 6 An exemplary schematic diagram of another satellite handover method is shown, such as Figure 6 As shown, after UE1 pre-handover, or after the SMF sends the Nx tunnel information of UE2's UPF2 to the target UPF1, UE2 also undergoes pre-handover. For example, through step 520, UE2 executes the pre-handover procedure, and UE2 is about to switch to base station 3 and UPF3 of the fifth satellite. In this case, the SMF can obtain the tunnel information of UE2's UPF3.

[0310] Specifically, there are several ways for the SMF to obtain the tunnel information of UE2's UPF3. For example, the SMF may receive a first update message, which includes the Nx tunnel information of UE2's UPF3. The first update message may be sent from UPF3 to the SMF, or it may be sent from the SMF corresponding to the PDU session of UE2 to the SMF (also referred to as the SMF corresponding to UE2). This application embodiment does not impose any restrictions.

[0311] Furthermore, the SMF can send the Nx tunnel information to the target UPF1, enabling communication between the target UPF1 and UPF3 based on the Nx tunnel information. It's important to note that since UE1 initiated the pre-handover process before UE2's pre-handover, the Nx tunnel information obtained by UE2's UPF3 during UE2's pre-handover process is already the Nx tunnel information of the target UPF1. Therefore, UPF3 can communicate with the target UPF1 in subsequent processes based on the target UPF1's Nx tunnel information. In another possible implementation, since UE1 has not yet switched during UE2's pre-handover process, the SMF can also send UE1's source Nx tunnel information to UPF3.

[0312] Specifically, there are several ways for SMF to send Nx tunnel information to target UPF1. For example, SMF can send the obtained Nx tunnel information of UPF3 to UPF1 through steps 514, 515 and 521.

[0313] For example, the SMF can carry the N4 container in step 514, and the N4 container can carry the Nx tunnel information of UPF3. The N4 container is transparently transmitted to the target UPF1 through the AMF and the target base station 1. The handover request message b11 sent by the target base station 1 to the target UPF1 in step 521 can include the N4 container. The handover response message b12 sent by the target UPF1 to the target base station 1 in step 522 can indicate that the Nx tunnel information of UPF3 has been received.

[0314] In another possible implementation, after UE2 performs the pre-handover procedure, or after SMF obtains the Nx tunnel information configured by UPF3 for UE2, the Nx tunnel information of UPF3 can be sent to the target UPF1 before step 514. This application embodiment does not impose any restrictions.

[0315] Based on the above Figure 5 or Figure 6 The content shown, Figure 7 An exemplary diagram illustrates yet another possible method in the pre-switching process, compared to Figure 5 or Figure 6 In other words, Figure 7The difference is that, in the pre-handover process, after the SMF receives the Session Management Context Update Request message b0 sent by the AMF through step 502, this embodiment configures the PDU session context for UE1 through steps 601a to 601i. Figure 7 The handover process of UE1 in the scheme shown is the same as Figure 5 or Figure 6 The content is the same as in the previous article, so I will not repeat it here.

[0316] like Figure 7 As shown, the following steps may be included after step 502:

[0317] Step 601a: SMF selects target UPF1, which is deployed on the same satellite as target base station 1, as the new UPF of UE1, and sends N4 session establishment request message c1 to target UPF1.

[0318] Accordingly, the target UPF1 receives the N4 session establishment request message c1.

[0319] In one possible implementation, when the PDU session of UE1 has an Nx tunnel, the N4 session establishment request message c1 may include the rules of the Nx tunnel information of UPF2.

[0320] In one possible implementation, when the SMF allocates a CN N3 tunnel for the target UPF1, the N4 session establishment request message c1 may also include rules regarding the CN N3 tunnel information.

[0321] In one possible implementation, when the SMF allocates an Nx tunnel for the target UPF1, the N4 session establishment request message c1 may also include rules for the Nx tunnel information.

[0322] Step 601b: Target UPF1 sends an N4 session establishment response message c2 to SMF.

[0323] Accordingly, the SMF receives the N4 session establishment response message c2.

[0324] In one possible implementation, when the SMF does not allocate a CN N3 tunnel for the target UPF1, but the target UPF1 allocates a CN N3 tunnel for the target UPF1, the N4 session establishment response message c2 may include CN N3 tunnel information.

[0325] In another possible implementation, when SMF does not allocate an Nx tunnel for target UPF1, but target UPF1 allocates an Nx tunnel for target UPF1, the N4 session establishment response message c2 may include Nx tunnel information.

[0326] Step 601c: SMF sends Session Management Context Update Response Message c3 to AMF.

[0327] Accordingly, the AMF receives the session management context update response message c3.

[0328] In one possible implementation, the session management context update response message c3 may include N2 session management information. In this embodiment, the N2 session management information can be transparently transmitted to the target base station 1 by the AMF. The N2 session management information in the session management context update response message c3 may include CN N3 tunnel information.

[0329] In step 601d, the AMF sends a pre-handover request message c4 to the target base station 1.

[0330] Correspondingly, target base station 1 receives pre-handover request message c4.

[0331] The pre-handover request message c4 can carry the N2 session management information from the session management context update response message c3. Thus, target base station 1 can obtain the CN N3 tunnel information from the pre-handover request message c4.

[0332] Step 601e: Target base station 1 sends a pre-handover response message c5 to AMF.

[0333] Accordingly, the AMF receives the pre-switching response message c5.

[0334] The pre-handover response message c5 may include the AN3 tunnel information of the target base station 1.

[0335] In one possible implementation, the pre-switching response message c5 may carry N2 session management information, which may include AN N3 tunnel information.

[0336] In another possible implementation, the pre-switching response message c5 includes rules for AN N3 tunnel information.

[0337] Step 601f: AMF sends a Session Management Context Update Request message c6 to SMF.

[0338] Correspondingly, SMF receives Session Management Context Update Request message c6.

[0339] In one possible implementation, the Session Management Context Update Request message c6 carries the N2 session management information carried in the pre-handover response message c5. This N2 session management information may include AN N3 tunnel information, allowing the SMF to determine the AN N3 tunnel information based on the N2 session management information.

[0340] In step 601g, SMF sends an N4 session update request message c7 to the target UPF1.

[0341] Accordingly, the target UPF1 receives the N4 session update request message c7.

[0342] The N4 session update request message c7 includes AN N3 tunnel information, for example, the N4 session update request message contains rules that include AN N3 tunnel information.

[0343] In step 601h, target UPF1 sends an N4 session update response message c8 to SMF.

[0344] Correspondingly, the SMF receives the N4 session update response message c8.

[0345] Step 601i: SMF sends a Session Management Context Update Response Message c9 to AMF.

[0346] Correspondingly, the AMF receives a Session Management Context Update Response Message c9 from the SMF. The Session Management Context Update Response Message c9 can be used to indicate that the context update of UE1's PDU session is complete.

[0347] Through steps 601a to 601i, target base station 1 obtains the N3 tunnel information of target UPF1, and target UPF1 also obtains the N3 tunnel information of target base station 1. Therefore, the N3 tunnel between target base station 1 and target UPF1 is established. Thus, after receiving data from UE1, target base station 1 can send it to target UPF1. Similarly, after receiving data for the PDU session that needs to be sent to UE1, target UPF1 can also send it to target base station 1, allowing target base station 1 to forward it to UE1.

[0348] It should be noted that, in addition to the above, the embodiments of this application also include... Figure 5 and Figure 7 In addition to the example of the SMF-triggered configuration of the PDU session context flow shown in the pre-switching process, there may be other processes for configuring the PDU session context of UE1, and this application embodiment does not impose any restrictions.

[0349] Based on the above, Figure 8 An exemplary flowchart illustrates yet another possible satellite handover method. Wherein, Figure 8 The following example illustrates the concept of a first communication device as the source base station 1 and a second communication device as the target base station. Figure 8 As shown, the method includes:

[0350] Step 701: Source base station 1 estimates that UE1 will switch from source base station 1 to target base station 1 at a future time.

[0351] For details regarding step 701, please refer to the aforementioned text. Figure 4aThe details of step 401 will not be repeated here.

[0352] Step 702: Source base station 1 sends a pre-handover request message d1 to source UPF1.

[0353] Correspondingly, the source UPF1 receives the pre-switching request message d1.

[0354] In step 702, the pre-handover request message d1 is used to request source UPF1 to prepare for the handover of UE1.

[0355] Step 703: Target base station 1 sends a pre-handover response message d2 to source base station 1.

[0356] Correspondingly, source base station 1 receives the pre-handover response message d2.

[0357] The pre-handover response message d2 may include a UPF container. The UPF container is prepared by the source UPF1 to send to the target UPF1. The information in the UPF container can be used to establish an N4 session between the target UPF1 and the SMF. Network elements (such as source base station 1, target base station 1, etc.) during the transmission process transparently transmit information to the UPF container. The UPF container may include the SMF information corresponding to the PDU session of UE1, as well as the context of the PDU session of UE1, etc.

[0358] Step 704: Source base station 1 sends a pre-handover request message d3 to target base station 1.

[0359] Accordingly, target base station 1 receives the pre-handover request message d3.

[0360] In step 704, the pre-handover request message d3 can be used to request the target base station 1 to prepare for the handover of UE1, such as creating a context for the handover of UE1's PDU session.

[0361] In one possible implementation, the pre-switch request message d3 carries the UPF container returned by the source UPF1.

[0362] In one possible implementation, the first request message sent by the first communication device mentioned in this application embodiment can be a pre-handover request message d3, which can indicate that UE1 is expected to be switched at a future time.

[0363] In another possible implementation, the source base station 1 may also send indication information to the target base station 1 to indicate which PDU sessions will be switched at a future time. For example, the source base station 1 may indicate which PDU sessions of UE1 will be switched in the future by sending a list of PDU sessions to the target base station 1.

[0364] In one possible implementation, the pre-handover request message d3 can reuse the handover request message in the existing standard. Furthermore, an indication message can be added to the message to indicate that UE1 is expected to be handed over at a future time.

[0365] In another possible implementation, the signaling of the pre-handover request message d3 can be redefined, which itself has the meaning of indicating that UE1 is expected to be handed over at a future time.

[0366] Step 705: Target base station 1 sends a pre-handover request message d4 to target UPF1.

[0367] Correspondingly, target UPF1 receives pre-switching request message d4.

[0368] In one possible implementation, target base station 1 can select target UPF1, which is deployed on the same satellite as itself, as the new UPF for UE1's PDU session, and then execute step 705, sending a pre-handover request message d4 to target UPF1. The pre-handover request message d4 may carry a UPF container.

[0369] In another possible implementation, the target base station 1 can also create a context for the PDU session of UE1, such as allocating an AN3 tunnel for the PDU session of UE1. The AN3 tunnel information is then carried in the pre-handover request message d4.

[0370] Step 706: Target UPF1 sends a pre-handover response message d5 to target base station 1.

[0371] Accordingly, target base station 1 receives the pre-handover response message d5.

[0372] In one possible implementation, the target UPF1 can create a context for UE1's PDU session, such as allocating a CN N3 tunnel for UE1's PDU session. If UE1's PDU session requires an Nx tunnel, the target UPF1 can also allocate an Nx tunnel for UE1's PDU session. This embodiment demonstrates the case where UE1's PDU session has an Nx tunnel. When UE1's PDU session does not have an Nx tunnel, the messages in this embodiment that include Nx tunnel information no longer have rules including Nx tunnel information.

[0373] In one possible implementation, the target UPF1 generates an N4 container based on the UPF container. The N4 container is sent by the target UPF1 to the SMF, and is used to establish an N4 session between the target UPF1 and the SMF. The N4 container may contain rules including CN N3 tunnel information and / or Nx tunnel information.

[0374] The pre-handover response message d5 may include N4 container and CN N3 tunnel information. The N4 container included in the pre-handover response message d5 can be transparently transmitted to the SMF by the target base station 1 and the AMF. The CN N3 tunnel information in the pre-handover response message d5 can be obtained by the target base station 1, and then the target base station 1 and the target UPF1 can communicate based on the N3 tunnel information on both sides.

[0375] Step 707: Target base station 1 sends a pre-handover request message d6 to AMF.

[0376] Correspondingly, the AMF receives the pre-handover request message d6.

[0377] The pre-handover request message d6 can indicate that UE1 is expected to be handed over at a future time.

[0378] The pre-handover request message d6 may include N2 session management information corresponding to multiple PDU sessions of UE1. The N2 session management information is sent by the target base station 1 to the SMF, and the AMF will pass it through to the SMF corresponding to the PDU session after receiving it. The N2 session management message may contain N4 container from the target UPF1 and AN N3 tunnel information from the target base station 1.

[0379] When the first communication device is the source base station 1 and the second communication device is the target base station 1, the seventh request message sent by the target base station 1 can be the pre-handover request message d4 in step 705 (in this case, the pre-handover response message d5 in step 706 can also be called the seventh response message), and the seventh request message sent by the target base station 1 can also be the pre-handover request message d6 in step 707 (in this case, the pre-handover response message d9 in step 711 can also be called the seventh response message). The seventh request message indicates that UE1 is expected to hand over to the first target access network device at a future time. Subsequently, the device receiving the seventh request message can prepare for the handover of UE1 based on the seventh request message.

[0380] Step 708: AMF sends a Session Management Context Update Request message d7 to SMF.

[0381] Correspondingly, SMF receives Session Management Context Update Request message d7.

[0382] The Session Management Context Update Request message d7 can indicate that UE1's PDU session is expected to be switched at a future time. For example, the Session Management Context Update Request message d7 can carry indication information indicating that UE1's PDU session is expected to be switched at a future time.

[0383] In one possible implementation, the Session Management Context Update Request message d7 includes N2 session management information. Thus, the SMF determines that the context update for UE1's PDU session is complete based on the received Session Management Context Update Request message d7 and can return to step 709. In other words, after receiving the Session Management Context Update Request message from step 708, the SMF does not need to initiate the process of creating a context for UE1's PDU session again and can execute step 709.

[0384] Step 709: SMF sends Session Management Context Update Response Message d8 to AMF.

[0385] Correspondingly, the AMF receives the Session Management Context Update Response Message d8.

[0386] The Session Management Context Update Response Message d8 in step 709 can indicate that the PDU session of UE1 has been switched to the target base station 1 and the configuration of the context has been completed.

[0387] In one possible implementation, the session management context update response message d8 in step 709 may carry an N4 container, which is transmitted to the target UPF1. This N4 container may include the Nx tunnel information of UPF2. Thus, when the target UPF1 receives the Nx tunnel information of UPF2 through subsequent step 712, the target UPF1 can communicate with UPF2 based on the Nx tunnel information. The N4 container can be transparently transmitted through subsequent steps 711 and 712.

[0388] Step 710: SMF sends N4 session update request message b8 to UPF2.

[0389] This step is optional. Correspondingly, UPF2 receives an N4 session update request message b8 from SMF. The N4 session update request message b8 may include the Nx tunnel information of the target UPF1.

[0390] Step 711, AMF sends a pre-handover response message d9 to target base station 1.

[0391] Correspondingly, target base station 1 receives pre-handover response message d9. Pre-handover response message d9 is used to indicate that the handover completion context has been updated for UE1.

[0392] In one possible implementation, in step 711, the AMF may carry the N4 container received in step 709 in the pre-switching response message d9.

[0393] Step 712, target base station 1 sends a pre-handover request message d10 to target UPF1.

[0394] Correspondingly, the target UPF1 receives the pre-switching request message d10.

[0395] In one possible implementation, in step 712, the target base station 1 may carry the N4 container received in step 711 in the pre-handover request message d10.

[0396] Step 713: Target UPF1 sends a pre-handover response message d11 to target base station 1.

[0397] Correspondingly, target base station 1 receives pre-handover response message d11, which can indicate that target UPF1 has received N4 container.

[0398] In another possible implementation, after step 708, the SMF can directly send the Nx tunnel information of UPF2 to the target UPF1. In this way, the N4 container does not need to be carried in the session management context update response message d8 in step 709. Correspondingly, the N4 container does not need to be carried in the pre-switching response message d9 in step 711, and steps 712 and 713 do not need to be executed.

[0399] Step 714: Target base station 1 sends a pre-handover response message d12 to source base station 1.

[0400] Correspondingly, source base station 1 receives the pre-handover response message d12.

[0401] The pre-handover response message d12 in step 714 may also include a pass-through container sent to UE1, which contains an RRC reconfiguration message. The pre-handover response message d12 may also be used to indicate that preparations have been made for the handover of UE1 or the handover of UE1's PDU session. Alternatively, the pre-handover response message d12 may be used to indicate that the pre-handover of UE1 is complete.

[0402] In this embodiment of the application, a switching process can also be executed after the pre-switching process. Figure 8 The switching process following the pre-switching process shown can be as described above. Figure 5 and Figure 7 The switching process is shown below.

[0403] In another possible implementation, due to Figure 8 In the illustrated scheme, during the pre-handover process, the source base station may obtain the transparent transmission container sent by the target base station 1 to UE1 through step 714. Therefore, when the source base station determines that UE1 needs to hand over to the target base station 1, it can skip steps 507 and 508 and directly execute step 509. The rest is the same as described above. Figure 5 and Figure 7 The relevant content is similar and will not be repeated here.

[0404] based on Figure 8 The proposed scheme Figure 9 An exemplary schematic diagram of yet another possible satellite handover method is shown. Figure 9 Pre-switching process and Figure 5 , Figure 6 , Figure 7 and Figure 8 The pre-switching process is different. Figure 9 The switching process can be referred to the above. Figure 5 , Figure 6 , Figure 7 or Figure 8 The content will not be repeated here.

[0405] like Figure 9 As shown, the method includes:

[0406] Step 801: Source base station 1 estimates that UE1 will switch from source base station 1 to target base station 1 at a future time.

[0407] For details regarding step 801, please refer to the aforementioned text. Figure 4a The details of step 401 will not be repeated here.

[0408] Step 802: Source base station 1 sends a pre-handover request message e1 to target base station 1.

[0409] Accordingly, target base station 1 receives the pre-handover request message e1.

[0410] The pre-handover request message e1 can indicate that UE1 is expected to be handed over at a future time. The pre-handover request message e1 can be used to request the target base station 1 to prepare for the handover of UE1, such as creating a context for the handover of UE1's PDU session.

[0411] compared to Figure 8 The method in the middle, Figure 9 The pre-switching request message e1 in the above text may no longer carry the UPF container. For other details about the pre-switching request message e1, please refer to the relevant description of the pre-switching request message d3 in step 704 above, which will not be repeated here.

[0412] Step 803: Target base station 1 sends a pre-handover request message e2 to AMF.

[0413] Correspondingly, the AMF receives the pre-switching request message e2.

[0414] The pre-handover request message e2 can indicate that UE1 is expected to be handed over at a future time.

[0415] The pre-handover request message e2 may include AN3 tunnel information created by the target base station 1 for the PDU session of UE1.

[0416] In one possible implementation, the pre-handover request message e2 may include N2 session management information of one or more PDU sessions of UE1. The N2 session management information may be transparently transmitted from AMF to SMF. The N2 session management information may include AN N3 tunnel information created by target base station 1 for the PDU session of UE1.

[0417] When the first communication device is the source base station 1 and the second communication device is the target base station 1, the seventh request message sent by the target base station 1 can be a pre-handover request message e2 (in this case, the pre-handover response message e7 in step 809 can also be called the seventh response message). The seventh request message indicates that UE1 is expected to hand over to the first target access network device at a future time. The device that receives the seventh request message can then prepare for the handover of UE1 based on the seventh request message.

[0418] Step 804: AMF sends a Session Management Context Update Request message e3 to SMF.

[0419] Correspondingly, SMF receives Session Management Context Update Request message e3.

[0420] The Session Management Context Update Request message e3 can indicate that UE1's PDU session is expected to be switched at a future time. For example, the Session Management Context Update Request message e3 can carry indication information indicating that UE1's PDU session is expected to be switched at a future time.

[0421] In one possible implementation, the Session Management Context Update Request message e3 includes N3 tunnel information created by the target base station 1 for the PDU session of UE1. For example, the Session Management Context Update Request message e3 includes N2 session management information from the pre-handover request message e2, and the N2 session management information may include AN N3 tunnel information. The Session Management Context Update Request message e3 may be a possible example of the eighth request message mentioned in the embodiments of this application.

[0422] Step 805, SMF sends an N4 session establishment request message e4 to the target UPF1.

[0423] Correspondingly, the target UPF1 receives the N4 session establishment request message e4. The N4 session establishment request message e4 can carry rules containing AN N3 tunnel information.

[0424] In step 805, the target UPF1 obtains the rules containing AN N3 tunnel information, and can then send the session data of the PDU received from UE2 to the target base station 1, so that the target base station 1 can send the data to UE1.

[0425] In another possible implementation, when the SMF allocates a CN N3 tunnel for the target UPF1, the N4 session establishment request message e4 may also contain rules that include CN N3 tunnel information.

[0426] In another possible implementation, when the SMF allocates Nx tunnel information to the target UPF1, the N4 session establishment request message e4 may also contain rules that include Nx tunnel information.

[0427] Step 806: Target UPF1 sends N4 session establishment response message e5 to SMF.

[0428] Correspondingly, the SMF receives the N4 session establishment response message e5.

[0429] In one possible implementation, when the SMF does not allocate CN N3 tunnel information to the target UPF1, but the target UPF1 allocates CN N3 tunnel information to the target UPF1, the N4 session establishment response message e5 can carry CN N3 tunnel information.

[0430] In another possible implementation, when the SMF does not allocate Nx tunnel information for the target UPF1, but the UE1's PDU session has Nx tunnel information, the target UPF1 allocates Nx tunnel information for the target UPF1, and the N4 session establishment response message e5 can carry the Nx tunnel information.

[0431] Step 807: SMF sends Session Management Context Update Response Message e6 to AMF.

[0432] Correspondingly, the AMF receives the Session Management Context Update Response Message e6.

[0433] The Session Management Context Update Response Message e6 can indicate that preparations have been made for the handover of UE1's PDU session to the target base station 1, that is, the user plane connection has been created for UE1's PDU session.

[0434] In one possible implementation, the Session Management Context Update Response Message e6 may carry CN N3 tunnel information established by the target UPF1 for the PDU session of UE1. For example, the Session Management Context Update Response Message e6 may carry N2 session management information, which may include CN N3 tunnel information, and this N2 session management information may be transparently transmitted by the AMF to the target base station 1. This allows the target base station 1 to obtain the CN N3 tunnel information. The Session Management Context Update Response Message e6 may be a possible example of the eighth response message mentioned in the embodiments of this application.

[0435] Step 808, SMF sends N4 session update request message b8 to UPF2.

[0436] This step is optional. Correspondingly, UPF2 receives an N4 session update request message b8 from SMF. The N4 session update request message b8 may include the Nx tunnel information of the target UPF1.

[0437] Step 809: AMF sends a pre-handover response message e7 to target base station 1.

[0438] Correspondingly, target base station 1 receives the pre-handover response message e7. The pre-handover response message e7 indicates that preparations have been made for the handover of UE1's PDU session to target base station 1, that is, the user plane connection has been created for UE1's PDU session.

[0439] In one possible implementation, the pre-handover response message e7 may carry CN N3 tunnel information established by the target UPF1 for the PDU session of UE1. Thus, the target base station 1 can communicate with the target UPF1 based on the acquired CN N3 tunnel information. The pre-handover response message e7 may be a possible example of the seventh response message mentioned in the embodiments of this application.

[0440] Step 810: Target base station 1 sends a pre-handover response message e8 to source base station 1.

[0441] Correspondingly, source base station 1 receives pre-handover response message e8.

[0442] The pre-handover response message e8 in step 810 may also include a transparent container sent to UE1, the transparent container containing an RRC reconfiguration message. The pre-handover response message e8 may also be used to indicate that the pre-handover of UE1 has been completed, i.e., a user plane connection has been created for UE1's PDU session. The pre-handover response message e8 may be a possible example of the first response message mentioned in the embodiments of this application.

[0443] In the embodiments of this application, when a network element (e.g., network element A) receives information from another network element (e.g., network element B), it can mean that network element A receives the information directly from network element B, or that network element A receives the information from network element B via another network element (e.g., network element C). When network element A receives information from network element B via network element C, network element C can either pass the information through or process the information, for example, by transmitting the information in different messages or by filtering the information and sending only the filtered information to network element A. Similarly, in the embodiments of this application, when network element A sends information to network element B, it can mean that network element A sends the information directly to network element B, or that network element A sends the information to network element B via another network element (e.g., network element C).

[0444] The terms "system" and "network" in the embodiments of this application can be used interchangeably. "At least one" means one or more, and "more than one" means two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can mean: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c can mean: a, b, c, ab, ac, bc, or abc, where a, b, and c can be single or multiple.

[0445] Furthermore, unless otherwise specified, the ordinal numbers such as "first" and "second" mentioned in the embodiments of this application are used to distinguish multiple objects and are not used to limit the order, sequence, priority or importance of multiple objects.

[0446] It should be noted that, in order to more clearly distinguish between the various messages in this embodiment, some messages have been given a sequence number for differentiation, such as Session Management Context Update Request Message b0 and Session Management Context Update Response Message b1. These sequence numbers are only for distinguishing between the messages and do not have any limiting meaning.

[0447] The names of the above messages are merely examples. As communication technology evolves, the names of any of the above messages may change. However, regardless of how the names change, as long as their meaning is the same as that of the messages mentioned in this application, they all fall within the protection scope of this application.

[0448] The above mainly describes the solution provided in this application from the perspective of interaction between various network elements. It is understood that, in order to achieve the above functions, each network element includes corresponding hardware structures and / or software modules for executing each function. Those skilled in the art should readily recognize that, based on the units and algorithm steps of the examples described in conjunction with the embodiments disclosed herein, this invention can be implemented in hardware or a combination of hardware and computer software. Whether a function is executed in hardware or by computer software driving hardware depends on the specific application and design constraints of the technical solution. Those skilled in the art 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 invention.

[0449] According to the aforementioned method, Figure 10 This is a schematic diagram of the structure of the communication device provided in the embodiments of this application, such as... Figure 10As shown, the communication device can be a first communication device or a second communication device (the second communication device can be an SMF or target base station 1, etc.), or it can be a chip or circuit, such as a chip or circuit that can be set in the first communication device, or a chip or circuit that can be set in the second communication device.

[0450] The communication device 1801 includes a processor 1802 and a transceiver 1803.

[0451] Furthermore, the communication device 1801 may include a memory 1804. The memory 1804 is shown as a dashed line in the figure, indicating that the memory is optional.

[0452] Furthermore, the communication device 1801 may further include a bus system, wherein the processor 1802, memory 1804, and transceiver 1803 can be connected through the bus system.

[0453] It should be understood that the processor 1802 described above can be a chip. For example, the processor 1802 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 micro controller unit (MCU), a programmable logic device (PLD), or other integrated chips.

[0454] In implementation, each step of the above method can be completed by the integrated logic circuitry of the hardware in the processor 1802 or by instructions in software form. The steps of the method disclosed in the embodiments of this application can be directly implemented by the hardware processor, or by a combination of hardware and software modules in the processor 1802. The software modules can reside in random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, or other mature storage media in the art. This storage medium is located in memory 1804, and the processor 1802 reads the information in memory 1804 and, in conjunction with its hardware, completes the steps of the above method.

[0455] It should be noted that the processor 1802 in this application embodiment can be an integrated circuit chip with signal processing capabilities. During implementation, each step of the above method embodiment can be completed by the integrated logic circuitry in the processor's hardware or by instructions in software form. The processor can be a general-purpose processor, digital signal processor (DSP), application-specific integrated circuit (ASIC), field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. It can implement or execute the methods, steps, and logic block diagrams disclosed in this application embodiment. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the methods disclosed in this application embodiment can be directly embodied as being executed by a hardware decoding processor, or executed by a combination of hardware and software modules in the decoding processor. The software modules can be located in random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, or other mature storage media in the art. This storage medium is located in memory; the processor reads information from the memory and, in conjunction with its hardware, completes the steps of the above method.

[0456] It is understood that the memory 1804 in the embodiments of this application can be volatile memory or non-volatile memory, or may include both volatile and non-volatile memory. The relevant description of the memory in the embodiments of this application can be found in the foregoing content, and will not be repeated here.

[0457] When communication device 1801 is the aforementioned first communication device, processor 1802 is configured to execute via transceiver 1803: anticipating a future handover of the first terminal device from a source access network device to a first target access network device, and sending a first request message. The first request message indicates that the Protocol Data Unit (PDU) session of the first terminal device is anticipated to be switched at a future time; or the first request message indicates that the first terminal device is anticipated to be switched at a future time. The source user plane function network element and the source access network device providing services for the PDU session prior to the handover are deployed on the first satellite.

[0458] When communication device 1801 is the second communication device mentioned above, such as an SMF, transceiver 1803 performs the following actions: receiving a first request message. The first request message indicates that the Protocol Data Unit (PDU) session of the first terminal device is expected to be switched at a future time. Sending a fifth request message, which requests the establishment of a context for the PDU session in the first target user plane function network element. The source user plane function network element and source access network device serving the PDU session before the switchover are deployed on the first satellite. The first target user plane function network element is the user plane function network element selected by the session management function network element to serve the PDU session after the switchover; the first target user plane function network element and the first target access network device serving the PDU session after the switchover are deployed on the second satellite.

[0459] When communication device 1801 is the second communication device mentioned above, such as target base station 1, transceiver 1803 is used to perform the following: receiving a first request message and sending a seventh request message. The first request message indicates that the first terminal device is expected to be switched at a future time. The source user plane function network element and source access network equipment providing services for the Protocol Data Unit (PDU) session before the switch are deployed on the first satellite. The seventh request message indicates that the PDU session of the first terminal device is expected to be switched to the first target access network equipment at a future time; the seventh request message includes the context of the first terminal device corresponding to the first target access network equipment.

[0460] For the concepts, explanations, detailed descriptions, and other steps related to the technical solutions provided in the embodiments of this application, please refer to the descriptions of these contents in the foregoing methods or other embodiments, which will not be repeated here.

[0461] According to the aforementioned method, Figure 11 This is a schematic diagram of the structure of the communication device provided in the embodiments of this application, such as... Figure 11 As shown, the communication device 1901 may include a communication interface 1903 and a processor 1902. Further, the communication device 1901 may include a memory 1904. The memory 1904 is shown as a dashed line in the figure, indicating that the memory is optional. The communication interface 1903 is used for inputting and / or outputting information; the processor 1902 is used to execute computer programs or instructions, enabling the communication device 1901 to perform the above-described functions. Figure 4a , Figure 5 , Figure 6 , Figure 7 , Figure 8 or Figure 9 The method on the first communication device side of any of the related solutions, or the method that enables communication device 1901 to achieve the above. Figure 4a , Figure 5 , Figure 6 , Figure 7 , Figure 8 or Figure 9 The method on the second communication device side of any of the related solutions. In the embodiments of this application, the communication interface 1903 can implement the above. Figure 10 The transceiver 1803 implements the above-mentioned solution, and the processor 1902 can implement it as described above. Figure 10 The processor 1802 implements the above scheme, and the memory 1904 can implement the above. Figure 10 The solution implemented by the memory 1804 will not be elaborated here.

[0462] Based on the above embodiments and the same concept, Figure 12 A schematic diagram of the communication device provided in the embodiments of this application, such as... Figure 12 As shown, the communication device 2001 can be a first communication device or a second communication device, or it can be a chip or circuit, such as a chip or circuit that can be set in the first communication device or the second communication device.

[0463] The communication device 2001 includes a processing unit 2002 and a communication unit 2003. Further, the communication device 2001 may or may not include a storage unit 2004. In the figure, the storage unit 2004 is shown as a dashed line, further indicating that the memory is optional.

[0464] Communication unit 2003 is used for inputting and / or outputting information; processing unit 2002 is used for executing computer programs or instructions, so that communication device 2001 can perform the above-mentioned functions. Figure 4a , Figure 5 , Figure 6 , Figure 7 , Figure 8 or Figure 9 The method on the first communication device side of any of the related solutions, or the method that enables communication device 2001 to achieve the above. Figure 4a , Figure 5 , Figure 6 , Figure 7 , Figure 8 or Figure 9 The method on the second communication device side of any of the related solutions. In the embodiments of this application, the communication unit 2003 can implement the above. Figure 10 The transceiver 1803 implements the above-mentioned solution, and the processing unit 2002 can implement the above-mentioned solution. Figure 10 The solution implemented by processor 1802, the storage unit 2004 can implement the above. Figure 10 The solution implemented by the memory 1804 will not be elaborated here.

[0465] According to the method provided in the embodiments of this application, this application also provides a computer program product, which includes: computer program code or instructions, which, when executed on a computer, cause the computer to perform... Figure 4a , Figure 5 , Figure 6 , Figure 7 , Figure 8 or Figure 9 The method of any one of the embodiments shown in any of the embodiments.

[0466] According to the method provided in the embodiments of this application, this application also provides a computer-readable storage medium storing program code, which, when executed on a computer, causes the computer to perform... Figure 4a , Figure 5 , Figure 6 , Figure 7 , Figure 8 or Figure 9 The method of any one of the embodiments shown in any of the embodiments.

[0467] According to the method provided in the embodiments of this application, this application also provides a chip system, which may include a processor. The processor is coupled to a memory and can be used to execute... Figure 4a , Figure 5 , Figure 6 , Figure 7 , Figure 8 or Figure 9 The method of any embodiment shown in any of the embodiments. Optionally, the chip system further includes a memory. The memory is used to store a computer program (also referred to as code or instructions). The processor is used to retrieve and run the computer program from the memory, causing the device on which the chip system is installed to perform... Figure 4a , Figure 5 , Figure 6 , Figure 7 , Figure 8 or Figure 9 The method of any one of the embodiments shown in any of the embodiments.

[0468] According to the method provided in the embodiments of this application, this application also provides a system that includes one or more of the aforementioned first communication devices and one or more second communication devices.

[0469] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product. A computer program product includes one or more computer instructions. When the computer instructions are loaded and executed on a computer, all or part of the flow or function according to the embodiments of this application is generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, computer instructions can be transmitted from one website, computer, server, or data center to another via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that integrates one or more available media. The available media can be magnetic media (e.g., floppy disks, hard disks, magnetic tapes), optical media (e.g., high-density digital video discs (DVDs)), or semiconductor media (e.g., solid-state disks (SSDs)).

[0470] It should be noted that a portion of this patent application contains copyrighted material. The copyright holder retains all rights except for making copies of the contents of patent documents or records from the patent office.

[0471] In the above-described device embodiments, the second communication device corresponds to the first communication device and the second or first communication device in the method embodiments. Corresponding modules or units execute corresponding steps. For example, a communication unit (transceiver) executes the receiving or sending steps in the method embodiments, while other steps besides sending and receiving can be executed by a processing unit (processor). The specific functions of each unit can be found in the corresponding method embodiments. There can be one or more processors.

[0472] The terms “component,” “module,” “system,” etc., used in this specification are used to refer to computer-related entities, hardware, firmware, combinations of hardware and software, software, or software in execution. For example, a component can be, but is not limited to, a process running on a processor, a processor, an object, an executable file, an execution thread, a program, and / or a computer. As illustrated, applications running on computing devices and computing devices can both be components. One or more components may reside in a process and / or an execution thread, and components may be located on a single computer and / or distributed among two or more computers. Furthermore, these components can be executed from various computer-readable media on which various data structures are stored. Components can communicate, for example, via local and / or remote processes based on signals having one or more data packets (e.g., data from two components interacting with another component between a local system, a distributed system, and / or a network, such as the Internet interacting with other systems via signals).

[0473] Those skilled in the art will recognize that the various illustrative logical blocks and steps 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 implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this application.

[0474] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0475] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0476] The units described as separate components may or may not be physically separate. 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 the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0477] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. If the function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium.

[0478] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A satellite handover method, characterized by, The method includes: The first communication device anticipates that the first terminal device will switch from the source access network device to the first target access network device at a future time. The first communication device sends a first request message; wherein, the first request message indicates that the Protocol Data Unit (PDU) session of the first terminal device is expected to be switched at a future time, or the first request message indicates that the first terminal device is expected to be switched at a future time; the source user plane function network element and the source access network device that provide services for the PDU session before the switch are deployed on the first satellite; The first request message indicates the user plane path after the PDU session handover is established.

2. The method of claim 1, wherein, The first communication device anticipates that the first terminal device will switch from the source access network device to the first target access network device at a future time, including: The first communication device estimates, based on the location information of the first terminal device and the motion trajectory of the first satellite, that the first terminal device will switch from the source access network device to the first target access network device at a future time.

3. The method as described in claim 1, characterized in that, The first communication device anticipates that the first terminal device will switch from the source access network device to the first target access network device at a future time, including: The first communication device receives a second request message, which indicates that the first terminal device is expected to switch from the source access network device to the first target access network device at a future time. Based on the second request message, the first communication device estimates that the first terminal device will switch from the source access network device to the first target access network device at a future time.

4. The method according to any one of claims 1-3, characterized in that, The first request message includes at least one of the following: information about the first target access network device, information about the first target user plane function network element, or information about the second satellite; The first target access network device and the first target user plane function network element are deployed on the second satellite.

5. The method according to any one of claims 1-3, characterized in that, After the first communication device sends the first request message, it further includes: The first communication device determines that the first terminal device switches to the first target access network device; The first communication device sends a third request message, which indicates that the PDU session has been switched.

6. The method as described in claim 5, characterized in that, The first communication device determines that the first terminal device switches to the first target access network device, including: The first communication device receives a first path switching request message from a first target access network device, the first path switching request message indicating that the PDU session has been switched; The first communication device determines, based on the first path switching request message, that the first terminal device has switched to the first target access network device, and that the PDU session has been switched.

7. The method according to any one of claims 1-3, characterized in that, After the first communication device sends the first request message, it further includes: The first communication device determines that the first terminal device switches to the second target access network device; the second target access network device is different from the first target access network device; The first communication device sends a fourth request message, which indicates that the PDU session is pending handover.

8. The method according to any one of claims 1-3, characterized in that, The first communication device sends a first request message, including: The first communication device sends the first request message to the session management function network element; or, The first communication device sends the first request message to the first target access network device or access and mobility management network element.

9. A satellite handover method, characterized in that, The method includes: The session management function network element receives a first request message, which indicates that the Protocol Data Unit (PDU) session of the first terminal device is expected to be switched at a future time; the source user plane function network element and the source access network device that provide services for the PDU session before the switch are deployed on the first satellite; the first request message indicates the establishment of the user plane path after the PDU session switch. The session management function network element sends a fifth request message, which requests the first target user plane function network element to configure the context of the PDU session; Wherein, the first target user plane function network element is the user plane function network element that provides services to the PDU session after the estimated handover; the first target access network device is the access network device that is estimated to provide services to the PDU session after the handover; the first target user plane function network element and the first target access network device are deployed on the second satellite.

10. The method as described in claim 9, characterized in that, The first request message includes at least one of the following: information about the first target access network device, information about the first target user plane function network element, or information about the second satellite.

11. The method as described in claim 9 or 10, characterized in that, After the session management function network element sends the fifth request message, it also includes: The session management function network element receives a fifth response message, which indicates that the first target user plane function network element has configured the context of the PDU session.

12. The method as described in claim 11, characterized in that, After receiving the fifth response message, the session management function network element also includes: The session management function network element receives a third request message, which is used to request an update to the context of the PDU session; When the third request message indicates that the PDU session has been switched, the session management function network element returns a third response message based on the indication information indicating that the PDU session has been switched. The third response message indicates that the PDU session context update is complete.

13. The method as described in claim 12, characterized in that, After receiving the third request message, the session management function network element also includes: If the third request message indicates that the PDU session is pending handover, the session management function network element returns a third response message based on the fifth response message, and the third response message indicates that the PDU session context update is complete.

14. The method as described in claim 11, characterized in that, After receiving the fifth response message, the session management function network element also includes: The session management function network element receives a fourth request message, which is used to request an update to the context information of the PDU session; the fourth request message indicates that the PDU session is awaiting handover. When the session management function network element determines that the PDU session is to be switched to the second target user plane function network element, it sends a sixth request message, which requests that the context of the PDU session be configured in the second target user plane function network element.

15. A satellite handover method, characterized in that, The method includes: The first target access network device receives a first request message, which indicates that the first terminal device is expected to be switched at a future time; the source user plane function network element and the source access network device that provide services for the protocol data unit (PDU) session of the first terminal device before the switch are deployed on the first satellite; the first request message indicates the establishment of the user plane path after the PDU session switch. The first target access network device sends a seventh request message, which includes information about the tunnel configured by the first target access network device for the PDU session; the seventh request message indicates that the first terminal device is expected to be switched at a future time.

16. The method as described in claim 15, characterized in that, After the first target access network device sends the seventh request message, it also includes: The first target access network device sends a first response message to the source access network device, the first response message instructing the first terminal device to complete the pre-handover; The first response message also includes Radio Access Control (RRC) configuration information required for the first terminal device to access the first target access network device.

17. The method as described in claim 15 or 16, characterized in that, After the first target access network device sends the seventh request message, it also includes: The first target access network device receives a message from the first terminal device indicating that the Radio Access Control (RRC) reconfiguration is complete. The first target access network device sends a first path switching request message, which indicates that the PDU session of the first terminal device has been switched.

18. A communication device, characterized in that, Including communication interfaces and processors: The communication interface is used for inputting and / or outputting signaling or data; The processor is configured to execute a computer-executable program, and to cause the method described in any one of claims 1-17 to be executed via the communication interface.

19. A communication device, characterized in that, Including processor and memory, The memory is used to store computer programs or instructions; The processor is configured to execute a computer program or instructions in the memory such that the method described in any one of claims 1-17 is performed.

20. A communication device, characterized in that, It includes a processing module and a communication module, wherein the processing module is used to execute the method as described in any one of claims 1-17 through the communication module.

21. A chip system, characterized in that, The method includes a processor coupled to a memory for executing a computer program or instructions stored in the memory such that the method described in any one of claims 1-17 is performed.

22. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable instructions, which, when invoked by a computer, cause the method described in any one of claims 1-17 to be executed.

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