A communication method and apparatus

Abstract

The application provides a communication method and device. For two terminal devices directly communicating through a satellite, when a first terminal device performs satellite borne UPF switching, not only a transmission path between the first terminal device and a source satellite (a first satellite) is maintained, but also a transmission path between the first terminal device and a target satellite (a third satellite) is established. In this way, before the switching is completed, the first terminal device and a second terminal device can transmit data through the two paths, ensuring the continuity of a session and a service, reducing service interruption on the terminal side, and improving communication stability.

Description

Technical Field

[0001] This application relates to the field of communication technology, and in particular to a communication method and apparatus. Background Technology

[0002] Traditional satellite communication systems typically rely on terrestrial networks for relays, resulting in excessively long communication links. This not only increases communication latency but also enhances system complexity. To address this issue, a direct connection between user equipment (UE) and low-Earth orbit (LEO) satellites has been proposed. This allows UEs to communicate directly with other user terminals via LEO satellites, eliminating relay links, significantly shortening communication links, reducing latency and complexity, and improving communication efficiency.

[0003] However, in non-terrestrial networks (NTN) communication architectures, the high mobility of low Earth orbit (LEO) satellites causes the service satellites that the UE connects to to change frequently, resulting in brief service interruptions and impacting service continuity. Summary of the Invention

[0004] To address the aforementioned issues, this application provides a communication method and apparatus to reduce service interruptions on the user equipment side and improve service continuity.

[0005] Firstly, this application provides a communication method. For two terminal devices communicating directly via satellite, before a handover occurs, there is a connection between the first terminal device and a first core network element (deployed on the first satellite), a connection between the second terminal device and a second core network element (deployed on the second satellite), and a connection between the first core network element and the second core network element. Thus, the first terminal device communicates with itself through the first and second core network elements. If the first satellite moves, the first terminal device will handover to a third satellite. The first network element establishes a connection between the second core network element and a third core network element on the third satellite. The first network element sends a first session modification request to the second core network element, instructing the second satellite to add a transmission path to the third core network element, and the first network element to establish a transmission path between the third core network element and the first terminal device. If the communication target of the first terminal device changes from the first satellite to the third satellite, the first network element deletes the connection between the second and first core network elements. Using the above method, when the first terminal device performs inter-satellite handover, it simultaneously establishes connections with the source satellite (first satellite) and the target satellite (third satellite). Before the handover is completed, data is transmitted through two paths to ensure the continuity of the session and service and reduce service interruptions on the terminal side.

[0006] The first network element establishes a transmission path between the third core network element and the first terminal device, which can be achieved in several ways: In one implementation, if the third satellite also includes a first access network element, then when the first network element establishes a transmission path between the third core network element and the first terminal device, it will be established through the first access network element. That is, when the first access network element and the third core network element are deployed on the same satellite, the transmission path between the third core network element and the first terminal device will be established through the first access network element.

[0007] In one implementation, if the satellite to which the second access network element corresponding to the first core network element belongs is not the first satellite, and the first terminal device is located in the service message corresponding to the satellite to which the second access network element belongs, then when the first network element establishes a transmission path between the third core network element and the first terminal device, it will establish the transmission path between the third core network element and the first terminal device through the second access network element. When the access network element and the core network element are deployed separately and only the core network element is switched, the first network element will use the original second access network element to establish the transmission path between the switched third core network element and the first terminal device.

[0008] In one implementation, if the satellite to which the second access network element corresponding to the first core network element belongs is not the first satellite, and the communication target of the first terminal device switches from the satellite to which the second access network element belongs to the satellite to which the third access network element belongs, then the first network element establishes a transmission path between the third core network element and the first terminal device through the third access network element. When the access network element and core network element are deployed separately and both switch simultaneously, due to the movement of the satellite to which the original access network element corresponding to the first terminal device belongs, to avoid service interruption caused by the instability of the transmission path established through the original access network element, the first network element will establish a transmission path between the switched third core network element and the first terminal device through the switched third access network element.

[0009] In one possible implementation, if the communication target of the first terminal device is switched from the first satellite to the third satellite, the first network element also notifies the second access network element corresponding to the first core network element to release the resources between the first terminal device and the first terminal device so as to use the switched satellite for communication.

[0010] In one possible implementation, the first network element notifies the second access network element corresponding to the first core network element to release resources between itself and the first terminal device, including: the first network element notifying the second access network element through the second network element to release resources between itself and the first terminal device.

[0011] In one possible implementation, the method further includes: if the first satellite and the second satellite are the same satellite, the first network element establishes a transmission path between the third core network element and the second terminal device; if the communication target of the second terminal device switches from the second satellite to the third satellite, the first network element deletes the connection between the second core network element and the third core network element. In scenarios where two terminal devices communicate via the same satellite, during satellite handover, one terminal device performs the handover first, followed by the other terminal device. This step-by-step handover avoids the possibility of too many path selections during simultaneous handover, reducing complexity.

[0012] In one possible implementation, if the second terminal device switches from the second satellite to the third satellite, the first network element notifies the second access network element corresponding to the first core network element to release the resources between the second terminal device and the first core network element.

[0013] In one possible implementation, if the first satellite and the second satellite are different satellites and the communication target of the second terminal device switches from the second satellite to the fourth satellite, then the first network element establishes a connection between the third core network element and the fourth core network element on the fourth satellite; the first network element sends a second session modification request to the third core network element, which instructs the third core network element to add a transmission path to the fourth core network element; the first network element establishes a transmission path between the fourth core network element and the second terminal device; if the communication target of the second terminal device switches from the second satellite to the fourth satellite, the first network element deletes the connection between the second core network element and the third core network element. That is, when the second terminal device also needs to perform a satellite handover, the connection between the fourth core network element corresponding to the handover and the third core network element corresponding to the first terminal device is established first, and then the connection between the fourth core network element and the second terminal device is established, thereby completing the satellite handover.

[0014] In one possible implementation, if the satellite to which the fourth access network element corresponding to the second core network element belongs is not the second satellite, and the second terminal device is located in the service message corresponding to the satellite to which the fourth access network element belongs, then the first network element establishes a transmission path between the fourth core network element and the second terminal device, including: the first network element establishing a transmission path between the fourth core network element and the second terminal device through the fourth access network element. When the core network element and the access network element are deployed separately, if only the satellite to which the core network element is located is switched, the first network element can establish a transmission path between the fourth core network element and the second terminal device through the original access network element (the fourth access network element).

[0015] In one possible implementation, if the satellite to which the fourth access network element corresponding to the second core network element belongs is not the second satellite, and the communication target of the second terminal device switches from the satellite to which the fourth access network element belongs to the satellite to which the fifth access network element belongs, the first network element establishes a transmission path between the fourth core network element and the second terminal device. This includes: the first network element establishing a transmission path between the fourth core network element and the second terminal device through the fifth access network element. When the access network element and the core network element are deployed separately on different satellites and both switchovers occur, since the satellite to which the original access network element belongs has moved, the first network element establishes a transmission path between the fourth core network element and the second terminal device through the corresponding fifth access network element after the switchover. This avoids service interruption caused by the instability of the transmission path established through the original fourth access network element.

[0016] In one possible implementation, the method further includes: if the second terminal device switches from the second satellite to the fourth satellite, the first network element notifies the fourth access network element corresponding to the second core network element to release the resources between the second terminal device and the second terminal device.

[0017] In one possible implementation, before the first network element establishes a connection between the second core network element and the third core network element, the method further includes: the first network element receiving a session update request sent by the second network element, the session update request indicating that the first terminal device needs to switch to the third satellite.

[0018] Similarly, when the second terminal device switches to the fourth satellite, before the first network element establishes a connection between the third core network element and the fourth core network element, the first network element receives a session update request sent by the second network element, which indicates that the second terminal device needs to switch to the fourth satellite.

[0019] Among them, the first network element is the Session Management Function (SMF) network element, the second network element is the Access and Mobility Management Function (AMF) network element, the first core network element is the User Plane Function (UPF) network element, and the first access network element is the base station.

[0020] Secondly, a communication method is provided, which is applied to a satellite communication system. The satellite communication system includes a first terminal device, a second terminal device, a first satellite communicating with the first terminal device, and a second satellite communicating with the second terminal device. The first satellite includes a first core network element, and the second satellite includes a second core network element. The first terminal device and the second terminal device communicate directly through the first satellite and the second satellite. The method includes: if the communication target of the first terminal device switches from the first satellite to a third satellite and a connection has been established between the second core network element and the third core network element in the third satellite, the second core network element receives a first session modification request sent by the first network element; the second core network element adds a transmission path to the third core network element locally according to the first session modification request.

[0021] Thirdly, a communication method is provided, comprising: a first network element receiving a session update request sent by a second network element, the session update request indicating that a first terminal device needs to switch from a first satellite to a third satellite, the first satellite including a first core network element; the first network element establishing a connection between a second core network element on the second satellite and a third core network element on the third satellite according to the session update request, the first terminal device communicating with itself through the first satellite and the second satellite; the first network element sending a first session modification request to the second core network element, the first session modification request indicating that the second core network element add a transmission path to the third core network element; the first network element establishing a transmission path between the third core network element and the first terminal device; the first network element deleting the connection between the second core network element and the first core network element, the first terminal device communicating with itself through the third satellite and the second satellite.

[0022] Fourthly, a communication method is provided, the method comprising: a second core network element receiving a first session modification request sent by a first network element, the first session modification request instructing the second core network element to add a transmission path to a third core network element, the second core network element being deployed on a second satellite, the third core network element being deployed on a third satellite, the third satellite being the satellite corresponding to a first terminal device after handover; the second core network element adding a transmission path to the third core network element locally according to the first session modification request, the second core network element having a local transmission path to the second terminal device; Before the first terminal device switches to the third satellite, the first terminal device communicates with the second terminal device through the first satellite and the second satellite; after the first terminal device switches to the third satellite, the first terminal device communicates with the second terminal device through the third satellite and the second satellite.

[0023] Fifthly, a communication device is provided, applied to a first network element in a satellite communication system, comprising a transceiver module and a processing module. The satellite communication system includes a first terminal device, a second terminal device, a first satellite communicating with the first terminal device, and a second satellite communicating with the second terminal device. The first satellite includes a first core network element, and the second satellite includes a second core network element. A connection exists between the first and second core network elements, and the first and second terminal devices communicate directly through the first and second satellites. The processing module is used to establish a connection between the second core network element and a third core network element on the third satellite if the communication target of the first terminal device switches from the first satellite to a third satellite. The transceiver module is used to send a first session modification request to the second core network element, instructing the second satellite to add a transmission path to the third core network element. The processing module is also used to establish a transmission path between the third core network element and the first terminal device. If the communication target of the first terminal device switches from the first satellite to the third satellite, the processing module is also used to delete the connection between the second core network element and the first core network element.

[0024] Sixthly, a communication device is provided, which is applied to a second core network element in a satellite communication system, including a transceiver module and a processing module. The satellite communication system includes a first terminal device, a second terminal device, a first satellite communicating with the first terminal device, and a second satellite communicating with the second terminal device. The first satellite includes a first core network element, and the second satellite includes a second core network element. The first terminal device and the second terminal device communicate directly through the first and second satellites. The transceiver module is used to receive a first session modification request sent by the first network element if the communication target of the first terminal device switches from the first satellite to a third satellite and a connection has been established between the second core network element and the third core network element in the third satellite. The processing module is used to add a transmission path to the third core network element locally according to the first session modification request.

[0025] A seventh aspect provides a communication device including a processor. The processor is coupled to a memory and can be used to execute instructions or data in the memory to implement the methods of any of the preceding aspects. Optionally, the device further includes a memory. Optionally, the device further includes a communication interface, to which the processor is coupled.

[0026] In one implementation, the communication interface may be a transceiver, or an input / output interface.

[0027] Eighthly, a processor is provided, comprising: an input circuit, an output circuit, and a processing circuit. The processing circuit is configured to receive signals through the input circuit and transmit signals through the output circuit, causing the processor to execute the method of any of the aspects.

[0028] In specific implementation, the processor can be one or more chips, the input circuit can be input pins, the output circuit can be output pins, and the processing circuit can be transistors, gate circuits, flip-flops, and various logic circuits. The input signal received by the input circuit can be received and input by, for example, but not limited to, a receiver, and the signal output by the output circuit can be, for example, but not limited to, output to and transmitted by a transmitter. Furthermore, the input circuit and the output circuit can be the same circuit, which is used as both the input circuit and the output circuit at different times. This application does not limit the specific implementation of the processor and various circuits.

[0029] A ninth aspect provides a communication device including a processor and a memory. The processor is used to read instructions stored in the memory and to receive signals via a receiver and transmit signals via a transmitter to execute the methods of any of the preceding aspects.

[0030] Optionally, the processor may be one or more, and the memory may be one or more.

[0031] In a tenth aspect, a computer program product is provided, the computer program product comprising: a computer program (also referred to as code or instructions) that, when the computer program is run, causes a computer to perform the methods of any of the preceding aspects.

[0032] Eleventhly, a computer-readable storage medium is provided that stores a computer program (also referred to as code or instructions) that, when run on a computer, causes the computer to perform the methods of any of the preceding aspects.

[0033] In a twelfth aspect, embodiments of this application provide a chip system including one or more processors for calling and executing instructions stored in memory, causing the methods described in the foregoing aspects to be performed. The chip system may be composed of chips or may include chips and other discrete devices.

[0034] The chip system may include input circuits or interfaces for transmitting information or data, and output circuits or interfaces for receiving information or data.

[0035] In a thirteenth aspect, a communication system is provided, including the aforementioned terminal device and first network element. Optionally, the system may further include other devices that communicate with the terminal device and / or the first network element. Attached Figure Description

[0036] Figure 1 A communication system architecture provided in this application embodiment; Figure 2 A schematic diagram of multiple connections based on regenerated NTN provided in this application embodiment; Figure 3 This application provides a schematic diagram of an end-to-end multi-connection scheme. Figure 4 An interaction diagram of a communication method provided in an embodiment of this application; Figures 5a-5d A schematic diagram of satellite handover provided in an embodiment of this application; Figures 6a-6d This is a schematic diagram illustrating a switching effect provided in an embodiment of this application; Figure 7a and Figure 7b This application provides a schematic diagram of a UE2 handover process. Figure 8 This is a schematic diagram of a step-by-step switching scenario provided in an embodiment of this application; Figure 9a A flowchart illustrating the establishment of a spaceborne UPF connection is provided in an embodiment of this application. Figure 9b A flowchart illustrating the handover process from UE2 to STA2 provided in this application embodiment; Figure 9c A flowchart illustrating the handover process from UE1 to STA1 provided in this application embodiment; Figure 10 A structural diagram of a communication device provided in an embodiment of this application; Figure 11 This is a structural diagram of another communication device provided in an embodiment of this application. Detailed Implementation

[0037] To enable those skilled in the art to better understand the solution of this application, the application scenario of the technical solution of this application will be described first below.

[0038] In an NTN network, the link between a terminal device and a satellite is called a service link, the link between a ground gateway station and a satellite is called a feeder link, and the link between different satellites is called an inter-satellite link (ISL). Figure 1 The diagram illustrates a communication system that may include network devices, such as... Figure 1 The satellite 20, gateway station 30, and data network 40 are shown. The communication system may also include terminal equipment, such as… Figure 1The UE10 and UE50 are shown. UE10 and UE50 communicate with satellite 20 via a service link, and satellite 20 communicates with gateway station 30 via a feeder link.

[0039] The NTN network can be divided into two forwarding modes: transparent forwarding and regenerative forwarding. In transparent forwarding mode, the satellite acts as a repeater and does not process the signal. Data is transmitted transparently between the satellite and the ground gateway station, enabling communication between ground user equipment and the ground network. For example, Figure 1 The solid lines in the diagram represent the transmission link in the communication scenario shown. In regenerative forwarding mode, the satellite integrates base station functions, including data processing, forwarding, and routing. Ground user equipment can communicate directly with the satellite, and the processing unit on the satellite processes and forwards the data. In regenerative forwarding mode, user equipment can conduct end-to-end (UE-Satellite-UE) communication through one or more satellites, and user plane traffic does not need to pass through the terrestrial network. Figure 1 The transmission link indicated by the dashed line shows that user plane traffic between UE10 and UE50 is routed via satellite and does not need to pass through the terrestrial network.

[0040] It should be noted that, Figure 1 An example is shown where UE10 and UE50 achieve end-to-end communication via a single satellite. Optionally, multiple satellites may be included, allowing UE10 and UE50 to achieve end-to-end communication via multiple satellites. Additionally, in Figure 1 In the application scenario shown, both the base station and the User Plane Function (UPF) are deployed on a single satellite. However, in practical applications, the base station and UPF can also be deployed separately on different satellites, with communication between the satellite deploying the base station and the satellite deploying the UPF via ISL.

[0041] Currently, when handing over in terrestrial communication networks or satellite communication systems that only deploy base stations, the UE can establish a connection with the target base station and then disconnect from the current base station. For example... Figure 2 The described communication architecture allows the UE to simultaneously access two NG-RAN access links when there is coverage overlap. The UE is in connected mode on at least one access link, and if a handover, radio link failure, or congestion occurs on one access link, user plane traffic can be switched to another available link.

[0042] In UE-Satellite-UE communication scenarios, the onboard UPF acts as an uplink classifier (UL CL), branch point (BP), and local PSA UPF to forward data traffic locally. If an inter-satellite handover occurs in UE-Satellite-UE communication, a single transmission path must remain available throughout the handover process. Since the states of UL CL / BP / PSA need to be synchronized in real time, high network latency or synchronization failure will result in brief service interruptions, impacting the quality of service communication.

[0043] Based on this, this application proposes a communication method. In a UE-Satellite-UE communication scenario, if the satellite deploying the UPF moves, the terminal device switches from the first satellite (with the first core network element deployed) to the third satellite (with the third core network element deployed). During the switching process, the UE can set up two (PDU) sessions on the 5G network. Based on these two PDU sessions, two independent user plane paths can be established and connected to the same data network, such as... Figure 3 As shown, during satellite handover, two available transmission paths are established, and the original path is disconnected after the handover is completed. During this process, the two UPFs managing these two PDU sessions will assign two independent IPs to the UE, and the UE will simultaneously have two independent IP streams for data transmission. Furthermore, for UE-Satellite-UE end-to-end handovers, since the user has access links with both the source and target satellites simultaneously during inter-satellite handovers, a step-by-step handover method can be adopted to avoid excessive path selection and reduce complexity. That is, when both UEs need to handover, the two UEs handover separately.

[0044] The communication method provided in this application is applicable to deploying a gNB and a UPF on the same satellite. This architecture allows IP packets to be forwarded directly locally, avoiding the additional latency caused by multiple forwardings, which is particularly important for low-latency services (such as IMS services). In 5G networks, data is transmitted based on IP, but is typically encapsulated within a GTP-U tunnel. The UPF parses the GTP-U to obtain standard IPv4 / IPv6 packets, and simultaneously manages the PDU session, assigning IP addresses to the UE. Considering the high mobility of LEO satellites, deploying the UPF and gNB on the same satellite can reduce the frequency of satellite communication path switching to some extent.

[0045] If the UPF and gNB are deployed separately (meaning they are deployed on different satellites), it is necessary to consider not only the handover of the gNB on the access network side, but also the changes to the UPF caused by the movement of LEO satellites. Changes to the UPF will release the communication resources of the original UPF, which will have a significant impact on the continuity of current services.

[0046] Because the communication method provided in this application establishes two available transmission paths during the handover process, and these paths are relatively stable, it can reduce the impact on service continuity during the handover process to a certain extent. Therefore, the architecture of deploying UPF and gNB separately is applicable not only to scenarios where only UPF is being switched, but also to scenarios where both gNB and UPF are being switched simultaneously.

[0047] Furthermore, this application is applicable to staring beams (where the satellite uses a phased array antenna to ensure that the beam always covers a fixed cell) and moving beams (where the beam direction remains unchanged and the coverage area moves with the satellite) as well as to two terminal devices located in the same cell or different cells, making it highly adaptable.

[0048] The network equipment involved in this application includes network-side equipment such as access networks and core networks. Access network equipment is sometimes also called access nodes. Access network equipment has wireless transceiver capabilities and is used to communicate with terminals. Access network equipment includes, but is not limited to, base stations, evolved NodeBs (eNodeBs), transmission reception points (TRPs) in the aforementioned communication systems, next-generation NodeBs (gNBs) in 5G mobile communication systems, access network equipment or modules of access network equipment in open RAN (ORAN) systems, satellites in NTN communication systems, base stations in future mobile communication systems, or access nodes in WiFi systems. Access network equipment can also be modules or units capable of implementing some of the functions of a base station. Access network equipment can be macro base stations, micro base stations, or indoor stations, relay nodes or donor nodes, or wireless controllers in cloud radioaccess network (CRAN) scenarios. Optionally, access network equipment can also be servers, wearable devices, or vehicle-mounted equipment, etc. For example, in vehicle-to-everything (V2X) technology, the access network equipment can be a roadside unit (RSU). Multiple access network devices in a communication system can be the same type of base station or different types of base stations. Base stations can communicate directly with terminals or via relay stations. Terminals can communicate with multiple base stations using different access technologies.

[0049] The embodiments of this application do not limit the specific technology or device form used in the access network equipment. In this application, the access network equipment is referred to as a network device. In this application, the apparatus for implementing the functions of the network device can be a network device itself, or it can be any apparatus capable of supporting the network device in implementing those functions, such as a processor, circuit, chip, or chip system. This apparatus can be installed in the network device or connected to and used with the network device. In the technical solutions provided in this application, the example of a network device being used to implement the functions of the network device is used to describe the technical solutions provided in this application.

[0050] The terminal devices in this application include various devices with wireless communication capabilities, which can be used to connect people, objects, machines, etc. These terminal devices can be widely applied in various scenarios, such as: cellular communication, D2D, V2X, peer-to-peer (P2P), M2M, MTC, IoT, virtual reality (VR), augmented reality (AR), industrial control, autonomous driving, telemedicine, smart grids, smart furniture, smart offices, smart wearables, smart transportation, smart cities, drones, robots, remote sensing, passive sensing, positioning, navigation and tracking, autonomous delivery, and other scenarios.

[0051] The terminal device can be a terminal in any of the above scenarios, such as an MTC terminal, an IoT terminal, etc. Terminal equipment can be user equipment (UE), terminal, fixed equipment, mobile station equipment or mobile equipment, subscriber unit, handheld device, vehicle-mounted equipment, wearable device, cellular phone, smartphone, session initialization protocol (SIP) phone, wireless data card, personal digital assistant (PDA), computer, tablet computer, laptop computer, wireless modem, handset, laptop computer, computer with wireless transceiver capability, smart book, vehicle, satellite, global positioning system (GPS) device, target tracking device, aircraft (e.g., drone, helicopter, multi-helicopter, quad-helicopter, or airplane), boat, remote control device, smart home device, industrial equipment, or devices built into the above devices (e.g., communication modules, modems, or chips in the above devices), or other processing devices connected to a wireless modem. For ease of description, the terminal device will be described below using the terminal or UE as an example.

[0052] In this embodiment, the device for implementing the functions of the terminal device can be the terminal device itself, or it can be a device that supports the terminal device in implementing the functions, such as a chip system or a chip. This device can be installed in the terminal device. In this embodiment, the chip system can be composed of chips, or it can include chips and other discrete devices.

[0053] Terminal devices can be deployed on land, including indoors or outdoors, handheld or vehicle-mounted; they can also be deployed on water; and they can also be deployed in the air on airplanes, balloons, and satellites. This application does not limit the scenario in which the terminal device is located. Furthermore, a terminal device can be a hardware device, or a software function running on dedicated hardware, or a software function running on general-purpose hardware, such as a virtualization function instantiated on a platform (e.g., a cloud platform), or an entity that includes dedicated or general-purpose hardware and software functions. This application does not limit the specific form of the terminal device.

[0054] To facilitate understanding of the technical solution of this application, specific embodiments will be described below.

[0055] See Figure 4 The figure is a flowchart of a communication method provided in an embodiment of this application, as shown below. Figure 4 The method described above can be applied to a satellite communication system, which includes a first terminal device, a second terminal device, a first satellite communicating with the first terminal device, and a second satellite communicating with the second terminal device. The first terminal device and the second terminal device communicate directly through the first satellite and the second satellite, including: S401: If the communication target of the first terminal device switches from the first satellite to the third satellite, the first network element establishes a connection between the second core network element and the third core network element on the third satellite.

[0056] The system comprises three core network elements: a first core network element deployed on a first satellite, a second core network element deployed on a second satellite, and a third core network element deployed on a third satellite, which serves as the handover target for the first terminal device. The first satellite to which the first core network element belongs is connected to the first terminal device, and the second satellite to which the second core network element belongs is connected to the second terminal device. Communication between the first and second terminal devices is achieved through the first and second satellites. Specifically, the first terminal device establishes a communication connection with the first core network element through an access network element; the second terminal device establishes a communication connection with the second core network element through an access network element. The access network element corresponding to the first terminal device and the access network element corresponding to the second terminal device can be the same network element or different network elements.

[0057] In this embodiment, when the core network element and the access network element are deployed on the same satellite, the following two scenarios can be considered: One scenario involves end-to-end communication between a first terminal device and a second terminal device via a satellite, on which the core network element UPF and access network element gNB are deployed. For example... Figure 5a As shown, in this scenario, the first terminal device UE1 and the second terminal device UE2 communicate directly via satellite Sat1. Both the first and second core network elements are UPF1, and the access network elements corresponding to both UE1 and UE2 are gNB1. When Sat1 moves, UE1 will switch from Sat1 to Sat3, with the third core network element being UPF3 within Sat3.

[0058] It should be noted that, in Figure 5aIn the scenario shown, both UE1 and UE2 will undergo handover. To avoid the problem of multiple paths being available due to simultaneous handover, a step-by-step handover will be adopted. In this embodiment, the handover will be described in the order of UE1 handover first, followed by UE2 handover. Of course, UE2 can also perform the handover first, followed by UE1 handover; this embodiment does not limit this.

[0059] Another scenario involves end-to-end communication between a first terminal device and a second terminal device via at least two satellites, each of which is equipped with a core network element (UPF) and an access network element (gNB). For example... Figure 5b As shown, in this scenario, the first terminal device UE1 communicates directly with satellite Sat1, and the second terminal device UE2 communicates directly with satellite Sat2. Satellite Sat1 includes UPF1 and gNB1, and satellite Sat2 includes UPF2 and gNB2. The two satellites communicate with each other via ISL. The first core network element is UPF1, and the second core network element is UPF2. When Sat1 moves, UE1 will switch from Sat1 to Sat3, and the third core network element will be UPF3 within Sat3.

[0060] It should be noted that, in Figure 5b In the scenario shown, Sat2 can also move, and the communication satellite corresponding to UE2 will also be switched. The specific switching process is the same as that of UE1.

[0061] In this embodiment, when the core network element and the access network element are deployed separately on different satellites, the following scenarios may be included: One scenario is that the onboard UPF switches independently. For example, Figure 5c As shown, UE1 and UE2 communicate end-to-end via gNB1, UPF1, UPF2, and gNB2. gNB1 is deployed on satellite Sat1, UPF1 on satellite Sat2, UPF2 on satellite Sat3, and gNB2 on satellite Sat4. In this scenario, if satellite Sat2 moves, UE1's corresponding Sat1 will switch from Sat2 to Sat5, with the third core network element being UPF3 in Sat5.

[0062] Another scenario involves switching between both the onboard UPF and the onboard gNB. For example, Figure 5dAs shown, UE1 and UE2 achieve end-to-end communication through gNB1, UPF1, UPF2, and gNB2. gNB1 is deployed on satellite Sat1, UPF1 on satellite Sat2, UPF2 on satellite Sat3, and gNB2 on satellite Sat4. In this scenario, both Sat1 and Sat2 move, and UE1's communication target will switch from Sat1 to Sat5 and from Sat2 to Sat6. The third core network element is UPF3 in Sat6.

[0063] In this embodiment, when the first satellite corresponding to the first terminal device moves, the first terminal device will switch from the first satellite to the third satellite, and the first network element will establish a connection between the second core network element and the third core network element. For example, in Figure 5a In the scenario shown, the first and second core network elements are both UPF1, and the third core network element is UPF3. The first network element establishes a connection between UPF1 and UPF3 through ISL. For example, in... Figure 5b In the scenario shown, the first core network element is UPF1, the second core network element is UPF2, and the third core network element is UPF3. The first network element establishes a connection between UPF2 and UPF3 through ISL. Figure 5c and Figure 5d In the scenario shown, the first core network element is UPF1, the second core network element is UPF2, and the third core network element is UPF3. The first network element establishes a connection between UPF2 and UPF3 through ISL.

[0064] In practical implementation, when the first terminal device needs to switch communication targets, it sends a handover request to the second network element through the access network element. This handover request indicates that the first terminal device needs to switch to the third satellite. Upon receiving the handover request, the second network element sends a session update request to the first network element. This session update request indicates that the first terminal device needs to switch from the first satellite to the third satellite to update its session. After receiving the session update request, the first network element establishes a connection between the second and third core network elements.

[0065] The first network element is a network element with session management functions, such as a session management function (SMF) entity. The second network element is responsible for handling functions such as mobility management of terminal devices and radio resource allocation, such as an access and mobility management function (AMF) entity.

[0066] S402: The first network element sends a first session modification request to the second core network element.

[0067] S403: The second core network element adds a transmission path to the third core network element locally based on the modification request of the first session.

[0068] During a handover, the first network element sends a first session modification request to the second core network element. This request instructs the second core network element to add a transmission path to the third core network element locally. Thus, the second core network element has two transmission paths: the original path to the first core network element and the newly added path to the third core network element. Upon receiving the first session modification request, the second core network element adds a forwarding route to the third core network element to its local forwarding routing table.

[0069] For example, in Figure 5a In the process, the second core network element UPF1 has a transmission path to gNB1. After session modification, a new transmission path from UPF1 to UPF3 is added. Figure 5b , Figure 5c and Figure 5d In the scenario shown, the second core network element UPF2 has a transmission path to UPF1. After session modification, a transmission path from UPF2 to UPF3 is added.

[0070] S404: The first network element establishes a transmission path between the third core network element and the first terminal device.

[0071] In this embodiment, the core network element corresponding to the first terminal device will switch from the first core network element to the third core network element. To achieve the switching purpose, the first network element will establish a transmission path between the third core network element and the first terminal device. That is, a transmission path after the switch is established.

[0072] Typically, terminal devices communicate with the core network via the access network. Therefore, when the core network element and the access network element are deployed on the same satellite, and the third satellite includes the first access network element, the first network element will establish a transmission path between the third core network element and the first terminal device through the first access network element. For example... Figure 5a and Figure 5bIn the scenario shown, the first access network element corresponding to the third core network element UPF3 is gNB3. Therefore, a transmission path is established between UPF3, gNB3, and UE1, as shown by the dashed line. When the core network element and access network element are deployed separately, and the first satellite moves, but the satellite belonging to the second access network element corresponding to the first core network element still provides service to the first terminal device (i.e., the first terminal device is still located in the serving cell corresponding to the satellite of the second access network), only onboard UPF handover occurs. In this scenario, the first network element will establish a transmission path between the third core network element and the first terminal device through the second access network element. For example, Figure 5c As shown, the second access network element corresponding to the first core network element UPF1 is gNB1. The SMF establishes the transmission path between UPF3 and UE1 through gNB1, as shown by the dashed line.

[0073] When core network elements and access network elements are deployed separately, and both the satellites belonging to the first and second access network elements move, the communication target of the first terminal device will switch not only from the first satellite to the third satellite, but also from the satellite belonging to the second access network element to the satellite belonging to the third access network element; that is, both the onboard UPF and the onboard gNB will switch. In this scenario, the first network element establishes a transmission path between the third core network element and the first terminal device through the third access network element. For example, Figure 5d As shown, the third core network element is UPF3 and the third access network element is gNB3; SMF establishes the transmission path between UPF3 and UE1 through gNB3, as shown by the dashed line.

[0074] After S404 is completed, there are two transmission paths for the first terminal device. Before the handover is completed, the first terminal device can communicate with the second terminal device through these two transmission paths, thereby ensuring session and service continuity.

[0075] S405: If the communication target of the first terminal device is switched from the first satellite to the third satellite, the first network element deletes the connection between the second core network element and the first core network element.

[0076] After the handover is complete, the connection between the second core network element and the first core network element will be deleted. That is, the original transmission path will be deleted, and the two terminal devices will communicate through a newly established transmission path. For example, in... Figure 5b , Figure 5c and Figure 5d In the scenario shown, SMF deletes the connection between UPF1 and UPF2.

[0077] In one possible implementation, when the communication target of the first terminal device switches from the first satellite to the third satellite, the first network element can also notify the second access network element corresponding to the first core network element to release resources between itself and the first terminal device. It should be noted that, since only the onboard UPF is switched, the switched UPF still needs to communicate with the first terminal device through the original onboard gNB, for example... Figure 5c As shown, in this scenario, the second access network element does not release the resources between itself and the first terminal device. Figure 5a , 5b as well as Figure 5d In the scenario shown, the SMF notifies gNB1 to release resources between itself and UE1. Specifically, the first network element sends a notification message to the second access network element, which instructs the second access network element to release resources between itself and the first terminal device.

[0078] Optionally, the first network element will notify the second access network element corresponding to the first core network element to release resources between itself and the first terminal device through the second network element. Specifically, after deleting the connection between the first core network element and the second core network element, the first network element can send a notification message to the second network element to inform it that the connection between the first core network element and the second core network element has been deleted. Then, the second network element will notify the second access network element to release resources between itself and the first terminal device.

[0079] After the first terminal device completes the handover, it will communicate with the second terminal device through the new third core network element. For example, regarding... Figure 5a and Figure 5b The scenario shown, the communication structure after switching is as follows: Figure 6a , Figure 6b As shown, UE1 communicates with UE2 through Sat3 and Sat1. Regarding... Figure 5c The scenario shown, the communication structure after switching is as follows: Figure 6c As shown, UE1 communicates with UE2 via Sat1, Sat5, Sat3, and Sat4. Regarding... Figure 5d The scenario shown, the communication structure after switching is as follows: Figure 6d As shown, UE1 communicates with UE2 through Sat5, Sat6, Sat3, and Sat4.

[0080] After the onboard UPF (and onboard gNB) corresponding to the first terminal device completes the handover, if the onboard UPF corresponding to the second terminal device also moves, the corresponding handover procedure will be executed. Specifically, this is divided into the following two scenarios: In one scenario, if the first satellite to which the first core network element belongs and the second satellite to which the second core network element belongs are the same satellite, and the communication target of the second terminal device switches from the second satellite to the third satellite, such as... Figure 5aIn the application scenario shown, since the connection between the second core network element and the third core network element has already been established, the first network element directly establishes a transmission path between the third core network element and the second terminal device. If the second terminal device switches from the second core network element to the third core network element (i.e., the second terminal device switches from the second satellite to the third satellite), the first network element deletes the connection between the second core network element and the third core network element. For example, Figure 7a As shown, a transmission path (indicated by the dashed line) is established between UPF3 and UE2. After this transmission path is established, before the second terminal device switches to the third core network element, UE2 can communicate with UE1 through two transmission paths to ensure communication continuity. After the second terminal device completes the switchover, the connection between UPF1 and UPF3 is deleted, and UE1 and UE2 communicate through Sat3.

[0081] Specifically, when establishing the transmission path between the third core network element and the second terminal device, the transmission path between the third core network element and the second terminal device will be established through the first access network element corresponding to the third core network element. For example... Figure 7a As shown, UE2 communicates with UPF3 via gNB3.

[0082] Furthermore, after the second terminal device completes the handover, the first network element will also notify the second access network element corresponding to the first core network element to release the resources between the second terminal device, thereby disconnecting the connection between the second access network element and the second terminal device.

[0083] In another scenario, if the first satellite and the second satellite are different satellites and the second satellite moves, the communication target of the second terminal device switches from the second satellite to the fourth satellite. The first network element establishes a connection between the third core network element and the fourth core network element on the fourth satellite. The first network element sends a second session modification request to the third core network element, which instructs the third core network element to add a transmission path to the fourth core network element. The first network element establishes a transmission path between the fourth core network element and the second terminal device.

[0084] If the communication target of the second terminal device is switched from the second satellite to the fourth satellite, the first network element deletes the connection between the second core network element and the third core network element.

[0085] For example, in completing Figure 6bAfter the handover, UE1 establishes a connection between UPF3 and UPF4 via ISL. Simultaneously, a second session modification request is sent to UP3, adding a transmission path from UPF3 to UPF4. A transmission path can also be established between UPF4 and UE2. Thus, UPF3 has two transmission paths to UE2. Before the handover is complete, UE1 can communicate with UE2 through both transmission paths. After the handover, the connection between UPF2 and UPF3 is deleted, so UE1 and UE2 communicate only using the new transmission paths.

[0086] The following two scenarios are included when establishing the transmission path between the fourth core network element and the second terminal device: One approach is to establish a transmission path between the core network element and the access network element if they are deployed separately and only the core network element is switched over. Specifically, if the satellite to which the fourth access network element corresponding to the second core network element belongs is not the second satellite, and the second terminal device is located in the serving cell corresponding to the satellite to which the fourth access network element belongs, then the first network element establishes the transmission path between the fourth core network element and the second terminal device through the access network element (fourth access network element) corresponding to the second core network element. For details on the implementation of this step, please refer to [link to relevant documentation]. Figure 5c Related descriptions.

[0087] Another approach is to deploy the core network element and access network element separately, and if both core and access network elements switch over (i.e., the satellite to which the fourth access network element corresponding to the second core network element belongs is not the second satellite, and the communication target of the second terminal device switches from the satellite to which the fourth access network element belongs to the satellite to which the fifth access network element belongs), then the first network element establishes a transmission path between the fourth core network element and the second terminal device through the fifth access network element. For details on the implementation of this step, please refer to [link to relevant documentation]. Figure 5d Related descriptions.

[0088] If the core network element and access network element are deployed separately and both the core network element and access network element undergo handover, when the first terminal device completes the handover, the first network element notifies the fourth access network element corresponding to the second core network element to release the resources between it and the second terminal device. That is, the first network element notifies the access network element before the handover to release the resources between it and the second terminal device so that the second terminal device can communicate with the first terminal device through the fifth access network element and the fourth core network element.

[0089] It should be noted that, in Figure 5b In the application scenario shown, if both UE1 and UE2 undergo handover, the two UEs will typically not be connected to the same satellite after the handover. Therefore, this application only considers satellite movement and not UE movement. Furthermore, since the two UEs were originally far apart and belonged to different cells (i.e., communicating through different satellites), and since the UEs do not move, the serving satellites after the handover will still be two different satellites.

[0090] To facilitate understanding of the switching process in this application, the following will be combined with... Figure 8 The application scenario shown illustrates how multipath transmission and step-by-step handover can be used to reduce service interruptions during satellite handover. Figure 8 In the scenario shown, the initial state is that UE1 and UE2 communicate through Sat1. As satellite Sat1 moves, UE2 first switches to Sat2 service, and then UE1 switches to Sat2 service. Sat1 and Sat2 are connected through ISL.

[0091] Figure 8 The satellite switching scenario shown may include the following process: ①UE1 and UE2 communicate under the Sat1 service; ②UE2 initiates the handover first, UPF1 and UPF2 establish a connection, and UE2 performs multipath transmission; ③UE2 completes the handover, at which point UE1 and UE2 are served by Sat1 and Sat2 respectively; ④UE1 performs a handover and establishes multipath transmission; ⑤ UE1 completes the handover, and UE1 and UE2 are jointly provided by Sat2.

[0092] It should be noted that the functions performed by the onboard UPF during uplink and downlink traffic transmission differ during handover. For example, during inter-satellite handover of UE2, UPF1 on Sat1 classifies or splits the uplink traffic of UE1 and integrates the traffic from multiple downlink paths. For UE1, UPF1 acts as UL CL (classifier) / BP (backup traffic) and PSA UPF1, while UPF2 acts as PSA UPF2. Establishing multiple access links may reduce the processing pressure on a single onboard UPF during handover and avoid service interruptions caused by BP / UL CL / additional PSA synchronization update failures.

[0093] in, Figure 8 The satellite switching process shown can be divided into the following three steps, which will be discussed below. Figures 9a-9c Explanation: (a) Establishing a connection between UPF1 and UPF2 Specifically, see Figure 9a The diagram showing the satellite-borne UPF connection establishment process includes: 0a. UE1 and UE2 communicate via satellite. UE1 is served by satellite SAT1, and UE2 is also served by satellite SAT1. The transmission path between the UEs is UE1 <-> SAT1(gNB1+UPF1) <-> UE2.

[0094] 0b-0c. Due to satellite movement, the UE's serving satellite may change. This procedure assumes that UE2 switches from satellite SAT1 to SAT2.

[0095] 1. The handover begins. The target gNB2 sends an N2 path handover request to the AMF. Before the handover, UE2 is only connected to gNB1. After the handover, UE2 is connected to both gNB1 and gNB2.

[0096] 2. The AMF sends an Nsmf_PDUSession_UpdateSMContext request to the SMF, which is used to notify the SMF that "UE2's path has been switched and switched to Sat2".

[0097] 3. Based on the target gNB2 and target satellite information, the SMF selects UPF2 on the target satellite as the I-UPF for UE-SAT-UE communication.

[0098] 4. UE2 can then be served by gNB2, which is the second RAN node, and establish a PDU session. The UPF on the ground is selected as the PSA UPF for the session.

[0099] 5a. SMF sends an N4 session establishment request to UPF2, which includes the access network tunnel information of gNB2, the core network tunnel information of UPF1, and the QoS flow information of the IMS media.

[0100] 5b.UPF2 returns a response for confirmation.

[0101] 6a. The SMF sends an N4 session modification request to modify the session information of the terrestrial UPF by updating the access network tunnel information of gNB2.

[0102] 6b. The ground-based UPF returns a response for confirmation.

[0103] 7a. SMF sends an N4 session modification request to UPF1, and modifies the session information related to UE2 in UPF1 by updating the core network tunnel information of UE2 and target UPF2, thereby establishing a connection between UPF1 and UPF2.

[0104] 7b.UPF1 returns a response for confirmation.

[0105] (ii) Switching from UE2 to SAT2 Specifically, see Figure 9b The diagram shown illustrates the UE2 to SAT2 handover process, including: 8. SMF adds UPF2 as the PDU session anchor point and BP / UL CL for UE2. At this time, multipath transmission is performed at UPF1, as shown by the two transmission paths, solid and dashed lines in the figure.

[0106] 9. After the two links are established, session and service continuity will be guaranteed. A timer can be set to automatically disconnect the original path after the timer expires. SMF deletes the original PDU session anchor point and BP / UL CL of UE2.

[0107] 10-11. The path switching response is sent from the SMF to the target gNB2 via the AMF.

[0108] 12. The serving satellite of UE2 is switched from SAT1 to SAT2. At this time, the transmission path between UE1 and UE2 is UE1<->SAT1(gNB1+UPF1)<->SAT2(UPF2+gNB2)<->UE2.

[0109] (iii) Switching from UE1 to Sat2 Specifically, see Figure 9c The diagram showing the UE1 to SAT2 handover process includes: 0a. UE1 and UE2 communicate via satellite. In this case, the transmission path between UE1 and UE2 is UE1<->SAT1(gNB1+UPF1)<->SAT2(UPF2+gNB2)<->UE2.

[0110] 0b-0c. Due to the movement of the satellite, UE1 switches from satellite SAT1 to SAT2.

[0111] 1. After the switch is executed, the target gNB2 sends an N2 path switch request.

[0112] 2. The AMF sends an Nsmf_PDUSession_UpdateSMContext request to the SMF.

[0113] 3. At this time, UE1 can be served by gNB2, which is the second RAN node, and establish a PDU session. The UPF on the ground is selected as the PSA UPF of the session.

[0114] 4a. SMF sends an N4 session establishment request to UPF2. This request message contains the access network tunnel information of gNB2, the core network tunnel information of UPF2, and the QoS flow information of the IMS media.

[0115] 4b.UPF2 returns a response for confirmation.

[0116] 5a. The SMF sends an N4 session modification request to modify the session information of the terrestrial UPF by updating the access network tunnel information of gNB2.

[0117] 5b. The ground-based UPF returns a response for confirmation.

[0118] 6a. SMF sends an N4 session modification request to UPF2, which modifies the session information related to UE1 in UPF2 by updating the core network tunnel information of UE1 and the target UPF2.

[0119] 6b.UPF2 returns a response for confirmation.

[0120] 7. SMF adds UPF2 as the PDU session anchor point and BP / UL CL for UE1. At this time, multipath transmission is performed at UPF2, as shown by the two transmission paths, solid and dashed lines in the figure.

[0121] 8. After the two links are established, session and service continuity will be guaranteed. A timer can be set to automatically disconnect the original path after the timer expires. SMF deletes the original PDU session anchor point and BP / UL CL of UE1.

[0122] 9-10. The path switching response is sent from the SMF to the target gNB2 via the AMF.

[0123] 11. The service satellite of UE1 is switched from SAT1 to SAT2. The transmission path between UE1 and UE2 is UE1<->SAT2(UPF2+gNB2)<->UE2.

[0124] It should be understood that Figures 1 to 9c The flowcharts or scene diagrams shown are for illustrative purposes only and are not intended to limit the embodiments of this application to the examples illustrated. In fact, those skilled in the art can interpret the embodiments based on... Figures 1 to 9c The examples in the document can be transformed into equivalent ways to obtain more implementations.

[0125] The above text combined Figures 1 to 9c This document describes in detail the communication method provided in the embodiments of this application. The following will combine... Figure 10 and Figure 11 The apparatus embodiments of this application are described in detail below. It should be understood that the apparatus of this application embodiments can perform the various methods of the foregoing embodiments of this application, that is, the specific working processes of the various products below can be referred to the corresponding processes in the foregoing method embodiments.

[0126] In the embodiments described above, the terminal device may execute some or all of the steps in each embodiment; the network device (first network element, second network element, core network element, and access network element) may execute some or all of the steps in each embodiment. These steps or operations are merely examples, and the embodiments of this application may also perform other operations or variations thereof. Furthermore, the steps may be executed in different orders as presented in the embodiments, and it is not necessary to execute all the operations in the embodiments of this application. Moreover, the sequence number of each step does not imply the order of execution; the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0127] Figure 10 This is a schematic block diagram of a communication device provided in an embodiment of this application. Figure 10 As shown, the communication device 1000 may include a communication module 1020. The communication module 1020 can implement corresponding communication functions, which can be internal communication functions of the communication device 1000 or communication functions between the communication device 1000 and other devices. Optionally, the communication module 1020 may also be referred to as a communication interface or transceiver module. Optionally, the communication device 1000 further includes a processing module 1010. The processing module 1010 can implement corresponding processing functions.

[0128] Optionally, the communication device 1000 further includes a storage module, which can be used to store instructions and / or data; the processing module 1010 can read the instructions and / or data in the storage module so that the communication device 1000 can implement the aforementioned method embodiments.

[0129] In one possible design, the communication device 1000 may correspond to the first network element in the above method embodiments, or a component (such as a circuit, chip, or chip system) configured in the first network element. The communication device 1000 may be used to execute the steps or processes performed by the first network element in any of the above method embodiments.

[0130] For example, the processing module 1010 is used to establish a connection between the second core network element and the third core network element on the third satellite if the communication target of the first terminal device switches from the first satellite to the third satellite; The communication module 1020 is used to send a first session modification request to the second core network element, which instructs the second satellite to add a transmission path to the third core network element; The processing module 1010 is used to establish a transmission path between the third core network element and the first terminal device; if the communication target of the first terminal device is switched from the first satellite to the third satellite, the connection between the second core network element and the first core network element is deleted.

[0131] In one possible implementation, if the third satellite also includes a first access network element, the processing module 1010 is specifically used to establish a transmission path between the third core network element and the first terminal device through the first access network element.

[0132] In one possible implementation, if the satellite to which the second access network element corresponding to the first core network element belongs is not the first satellite and the first terminal device is located in the serving cell corresponding to the satellite to which the second access network element belongs, the processing module 1010 is specifically used to establish a transmission path between the third core network element and the first terminal device through the second access network element.

[0133] In one possible implementation, if the satellite to which the second access network element corresponding to the first core network element belongs is not the first satellite and the communication target of the first terminal device switches from the satellite to which the second access network element belongs to the satellite to which the third access network element belongs, the processing module 1010 is specifically used to establish a transmission path between the third core network element and the first terminal device through the third access network element.

[0134] In one possible implementation, the communication module 1020 is further configured to notify the second access network element corresponding to the first core network element to release resources between the first terminal device and the first terminal device if the communication target of the first terminal device switches from the first satellite to the third satellite.

[0135] In one possible implementation, the communication module 1020 is specifically used to notify the second access network element to release resources between itself and the first terminal device via the second network element.

[0136] In one possible implementation, the processing module 1010 is further configured to establish a transmission path between the third core network element and the second terminal device if the first satellite and the second satellite are the same satellite; and to delete the connection between the second core network element and the third core network element if the communication target of the second terminal device is switched from the second satellite to the third satellite.

[0137] In one possible implementation, the processing module 1010 is further configured to, if the second terminal device switches from the second satellite to the third satellite, notify the second access network element corresponding to the first core network element to release the resources between the second terminal device and the second terminal device.

[0138] In one possible implementation, the processing module 1010 is further configured to establish a connection between the third core network element and the fourth core network element on the fourth satellite if the first satellite and the second satellite are different satellites and the communication target of the second terminal device switches from the second satellite to the fourth satellite. The communication module 1020 is also used to send a second session modification request to the third core network element, the second session modification request instructing the third core network element to add a transmission path to the fourth core network element; The processing module 1010 is also used to establish a transmission path between the fourth core network element and the second terminal device; if the communication target of the second terminal device switches from the second satellite to the fourth satellite, the connection between the second core network element and the third core network element is deleted.

[0139] In one possible implementation, the processing module 1010 is specifically used to establish a transmission path between the fourth core network element and the second terminal device through the fourth access network element if the satellite to which the fourth access network element belongs is not the second satellite and the second terminal device is located in the serving cell to which the fourth access network element belongs.

[0140] In one possible implementation, the processing module 1010 is specifically used to establish a transmission path between the fourth core network element and the second terminal device if the satellite to which the fourth access network element to which the second core network element belongs is not the second satellite and the communication target of the second terminal device is switched from the satellite to which the fourth access network element belongs to the satellite to which the fifth access network element belongs.

[0141] In one possible implementation, the communication module 1020 is further configured to notify the fourth access network element corresponding to the second core network element to release resources between the second terminal device and the second terminal device if the second terminal device switches from the second satellite to the fourth satellite.

[0142] In one possible implementation, the communication module 1020 is further configured to receive a session update request sent by the second network element before establishing a connection between the second core network element and the third core network element. The session update request indicates that the first terminal device needs to switch to the third satellite.

[0143] In one possible implementation, the first network element is a Session Management Function (SMF), the second network element is an Access and Mobility Management Function (AMF), the first core network element is a User Plane Function (UPF), and the first access network element is a base station.

[0144] The above are merely examples; for detailed steps or procedures, please refer to the descriptions in the foregoing embodiments.

[0145] In one possible design, the communication device 1000 may correspond to the second core network element in the above method embodiments, or a component (such as a circuit, chip, or chip system) configured in the second core network element. The communication device 400 may be used to execute the steps or processes performed by the second core network element in any of the above method embodiments.

[0146] For example, the communication module 1020 is used to receive a first session modification request sent by the first network element if the communication target of the first terminal device switches from the first satellite to the third satellite and the connection between the second core network element and the third core network element in the third satellite has been established. The processing module 1010 is used to add a transmission path to the third core network element locally according to the first session modification request.

[0147] The above are merely examples; for detailed steps or procedures, please refer to the descriptions in the foregoing embodiments.

[0148] Figure 11 This is another schematic block diagram of the communication device 1100 provided in the embodiments of this application. The communication device 1100 may be a chip, chip system, or processor, etc., used by a terminal device or network device to implement the above-described methods. The communication device 1100 can be used to implement the methods described in the above-described method embodiments; for details, please refer to the descriptions in the above-described method embodiments.

[0149] like Figure 11 As shown, the communication device 1100 may include one or more processors 1110, which may also be referred to as processing units or processing modules, and can implement certain control functions. The processor 1110 may be a general-purpose processor or a dedicated processor, such as a baseband processor or a central processing unit. The baseband processor can be used to process communication protocols and communication data, while the central processing unit can be used to control the communication device 1100 (e.g., a base station, baseband chip, user, user chip), execute software programs, and process data from the software programs.

[0150] In an alternative design, the processor 1110 may also store instructions and / or data that can be executed by the processor 1110 to cause the communication device 1100 to perform the methods described in the above method embodiments.

[0151] In another alternative design, the communication device 1100 may include a communication interface 1120 for implementing receiving and transmitting functions. For example, the communication interface 1120 may be a transceiver circuit, interface, interface circuit, or transceiver. The transceiver circuit, interface, interface circuit, or transceiver for implementing receiving and transmitting functions may be separate or integrated. The aforementioned transceiver circuit, interface, interface circuit, or transceiver may be used for reading and writing code / data, or it may be used for transmitting or relaying signals.

[0152] Optionally, the communication device 1100 may include one or more memories 1130, which may store instructions that can be executed on the processor 1110, causing the communication device 1100 to perform the methods described in the above method embodiments. Optionally, the memories 1130 may also store data. Optionally, the processor 1110 may also store instructions and / or data. The processor 1110 and the memories 1130 may be provided separately or integrated together.

[0153] It should be understood that, in one possible design, the steps in the method embodiments provided in this application can be implemented by integrated logic circuits in the processor's hardware or by instructions in software form. The steps of the methods disclosed in the embodiments of this application can be directly implemented by a hardware processor, or implemented by a combination of hardware and software modules in the processor. 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, and the processor reads information from the memory and, in conjunction with its hardware, completes the steps of the above method. To avoid repetition, detailed descriptions are not provided here.

[0154] In one implementation, the communication device 1100 may correspond to the terminal device in the above method embodiments, and may be used to execute the various steps and / or processes executed by the terminal device in the above method embodiments. The processor 1110 may be used to execute instructions stored in the memory 1130, and when the processor 1110 executes the instructions stored in the memory, the processor 1110 is used to execute the various steps and / or processes of the above method embodiments corresponding to the terminal device.

[0155] In another implementation, the communication device 1100 can correspond to the network device in the above method embodiments, such as a first network element, a second network element, or a second core network element, and can be used to execute the various steps and / or processes executed by the network device in the above method embodiments. The processor 1110 can be used to execute the instructions stored in the memory 1130, and when the processor 1110 executes the instructions stored in the memory, the processor 1110 is used to execute the various steps and / or processes of the above method embodiments corresponding to the network device.

[0156] It should be understood that the aforementioned processing device can be one or more chips. For example, the processing device can be a field-programmable gate array (FPGA), an application-specific integrated circuit (ASIC), a system-on-chip (SoC), a central processor unit (CPU), a network processor (NP), a digital signal processor (DSP), a microcontroller unit (MCU), a programmable logic device (PLD), or other integrated chips.

[0157] It is understood that the memory in the embodiments of this application can be volatile memory or non-volatile memory, or may include both volatile and non-volatile memory. The non-volatile memory can be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. The volatile memory can be random access memory (RAM), which is used as an external cache. By way of example, but not limitation, many forms of RAM are available, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous linked dynamic random access memory (SLDRAM), and direct rambus RAM (DR RAM). It should be noted that the memory used in the systems and methods described herein is intended to include, but is not limited to, these and any other suitable types of memory.

[0158] According to the method provided in the embodiments of this application, this application also provides a chip system, which includes one or more processors for calling and executing instructions stored in memory, thereby causing the method described in the embodiments of this application to be executed. The chip system may be composed of chips or may include chips and other discrete devices.

[0159] The chip system may include input circuits or interfaces for transmitting information or data, and output circuits or interfaces for receiving information or data.

[0160] According to the method provided in the embodiments of this application, this application also provides a communication system, which includes the aforementioned terminal device and network device.

[0161] According to the method provided in the embodiments of this application, this application also provides a computer program product, which includes: computer program code, which, when run on a computer, causes the computer to execute the various steps or processes executed by the terminal device or network device in any of the foregoing method embodiments.

[0162] 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 run on a computer, causes the computer to execute the various steps or processes executed by the terminal device or network device in any of the foregoing method embodiments.

[0163] The computer-readable storage medium may be the aforementioned volatile memory or non-volatile memory, or it may include both volatile memory and non-volatile memory.

[0164] In the embodiments of this application, the terms and English abbreviations are exemplary examples given for ease of description and should not be construed as limiting the application in any way. This application does not preclude the possibility of defining other terms that can achieve the same or similar functions in existing or future agreements.

[0165] 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. The computer program product includes one or more computer instructions. When these computer instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated.

[0166] 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.

[0167] It should be understood that in the various embodiments of this application, the sequence number of each process does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0168] In summary, the above description is merely a preferred embodiment of the technical solution of this application and is not intended to limit the scope of protection of this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A communication method, characterized in that, The method is applied to a satellite communication system, which includes a first terminal device, a second terminal device, and a first satellite. The first satellite includes a first core network element. The first terminal device and the second terminal device are in a first communication state, which means that the first terminal device communicates directly with the second terminal device through a PDU session anchored at the first core network element, including: When both the first terminal device and the second terminal device need to perform satellite handover, the first terminal device and the second terminal device enter the second communication state from the first communication state. The second communication state means that the first terminal device communicates with the second terminal device through the second core network element anchored on the second satellite and through the PDU session of the first core network element. The second satellite refers to the target satellite for handover. After both the first terminal device and the second terminal device have completed satellite handover, the first terminal device and the second terminal device enter the third communication state from the second communication state. The third communication state refers to the first terminal device communicating with the second terminal device through a PDU session anchored at the second core network element. The process by which the first terminal device and the second terminal device transition from the first communication state to the second communication state includes: The first network element establishes a connection between the first core network element and the second core network element; The first network element sends a first session modification request to the first core network element, and the first session modification request instructs the first core network element to add a transmission path to the second core network element; The first network element establishes a transmission path between the second core network element and the first terminal device. The transmission path refers to a newly added PDU session with the second core network element as the anchor point. The first network element deletes the connection between the first terminal device and the first core network element; The process by which the first terminal device and the second terminal device transition from the second communication state to the third communication state includes: The first network element establishes a transmission path between the second core network element and the second terminal device. The transmission path refers to a newly added PDU session with the second core network element as the anchor point. The first network element deletes the connection between the second terminal device and the first core network element.

2. The method according to claim 1, characterized in that, During the process of the first terminal device and the second terminal device transitioning from the first communication state to the second communication state, the first terminal device simultaneously communicates with the second terminal device through a PDU session anchored at the first core network element and a PDU session anchored at the second core network element and passing through the first core network element. The Internet Protocol IP address allocated by the second core network element to the first terminal device is different from the IP address allocated by the first core network element to the first terminal device.

3. The method according to claim 1, characterized in that, During the process of the first terminal device and the second terminal device transitioning from the second communication state to the third communication state, the second terminal device simultaneously communicates with the first terminal device through a PDU session anchored at the first core network element and passing through the second core network element, as well as a PDU session anchored at the second core network element. The Internet Protocol IP address allocated by the second core network element to the second terminal device is different from the IP address allocated by the first core network element to the second terminal device.

4. The method according to claim 1, characterized in that, The second satellite also includes a first access network element, which establishes a transmission path between the second core network element and the first terminal device, including: The first network element establishes a transmission path between the second core network element and the first terminal device through the first access network element; The first network element establishes a transmission path between the second core network element and the second terminal device, including: The first network element establishes a transmission path between the second core network element and the second terminal device through the first access network element.

5. The method according to claim 1, characterized in that, If the satellite to which the second access network element corresponding to the first core network element belongs is not the first satellite and the first terminal device is located in the serving cell corresponding to the satellite to which the second access network element belongs, the first network element establishes a transmission path between the second core network element and the first terminal device, including: The first network element establishes a transmission path between the second core network element and the first terminal device through the second access network element.

6. The method according to claim 1, characterized in that, If the satellite to which the second access network element corresponding to the first core network element belongs is not the first satellite, and the communication target of the first terminal device switches from the satellite to which the second access network element belongs to the satellite to which the third access network element belongs, the first network element establishes a transmission path between the second core network element and the first terminal device, including: The first network element establishes a transmission path between the second core network element and the first terminal device through the third access network element.

7. The method according to claim 4 or 6, characterized in that, The method further includes: After the first terminal device enters the second communication state, the first network element notifies the second access network element corresponding to the first core network element to release the resources between the first terminal device and the first terminal device.

8. The method according to claim 7, characterized in that, The first network element notifies the second access network element corresponding to the first core network element to release resources between itself and the first terminal device, including: The first network element notifies the second access network element through the second network element to release resources between itself and the first terminal device.

9. The method according to claim 1, characterized in that, The method further includes: After the second terminal device enters the third communication state, the first network element deletes the connection between the first core network element and the second core network element.

10. The method according to claim 9, characterized in that, The method further includes: The first network element notifies the second access network element corresponding to the first core network element to release resources between itself and the second terminal device.

11. The method according to claim 1, characterized in that, If the satellite to which the second access network element corresponding to the first core network element belongs is not the first satellite and the second terminal device is located in the serving cell corresponding to the satellite to which the second access network element belongs, the first network element establishes a transmission path between the second core network element and the second terminal device, including: The first network element establishes a transmission path between the second core network element and the second terminal device through the second access network element.

12. The method according to claim 1, characterized in that, If the satellite to which the second access network element corresponding to the first core network element belongs is not the first satellite, and the communication target of the second terminal device switches from the satellite to which the second access network element belongs to the satellite to which the third access network element belongs, the first network element establishes a transmission path between the second core network element and the second terminal device, including: The first network element establishes a transmission path between the second core network element and the second terminal device through the third access network element.

13. The method according to claim 1, characterized in that, Before the first network element establishes a connection between the first core network element and the second core network element, the method further includes: The first network element receives a session update request sent by the second network element, the session update request indicating that the first terminal device needs to switch to the second satellite.

14. The method according to claim 1, characterized in that, The first network element is the Session Management Function (SMF) network element, the second network element is the Access and Mobility Management Function (AMF) network element, the first core network element is the User Plane Function (UPF) network element, and the first access network element is the base station.

15. A communication method, characterized in that, The method is applied to a satellite communication system, which includes a first terminal device, a second terminal device, and a first satellite. The first satellite includes a first core network element. The first terminal device and the second terminal device are in a first communication state, which means that the first terminal device communicates directly with the second terminal device through a PDU session anchored at the first core network element, including: When both the first terminal device and the second terminal device need to perform satellite handover, the first terminal device and the second terminal device enter the second communication state from the first communication state. The second communication state means that the first terminal device communicates with the second terminal device through the second core network element anchored on the second satellite and through the PDU session of the first core network element. The second satellite refers to the target satellite for handover. After both the first terminal device and the second terminal device have completed satellite handover, the first terminal device enters the third communication state from the second communication state. The third communication state refers to the first terminal device communicating with the second terminal device through a PDU session anchored at the second core network element. The process by which the first terminal device and the second terminal device transition from the first communication state to the second communication state includes: The first core network element receives the first session modification request sent by the first network element; According to the first session modification request, the first core network element adds a transmission path to the second core network element locally. There is a transmission path between the second core network element and the first terminal device. The transmission path refers to the PDU session added with the second core network element as the anchor point. After the first terminal device enters the second communication state, the connection between the first terminal device and the first core network element is disconnected. During the process of the first terminal device and the second terminal device transitioning from the second communication state to the third communication state, there is a transmission path between the second core network element and the second terminal device. The transmission path refers to a newly added PDU session anchored by the second core network element. After the second terminal device enters the third communication state, the connection between the second terminal device and the first core network element is disconnected.

16. The method according to claim 15, characterized in that, During the process of the first terminal device and the second terminal device transitioning from the first communication state to the second communication state, the first terminal device simultaneously communicates with the second terminal device through a PDU session anchored at the first core network element and a PDU session anchored at the second core network element and passing through the first core network element. The Internet Protocol IP address allocated by the second core network element to the first terminal device is different from the IP address allocated by the first core network element to the first terminal device.

17. The method according to claim 15, characterized in that, During the process of the first terminal device and the second terminal device transitioning from the second communication state to the third communication state, the second terminal device simultaneously communicates with the first terminal device through a PDU session anchored at the first core network element and passing through the second core network element, as well as a PDU session anchored at the second core network element. The Internet Protocol IP address allocated by the second core network element to the second terminal device is different from the IP address allocated by the first core network element to the second terminal device.

18. A communication method, characterized in that, The method includes: During the process of the first terminal device and the second terminal device transitioning from the first communication state to the second communication state, the first network element establishes a connection between the first core network element on the first satellite and the second core network element on the second satellite. The first communication state refers to the first terminal device communicating directly with the second terminal device through a PDU session anchored at the first core network element. The second communication state refers to the first terminal device communicating with the second terminal device through a PDU session anchored at the second core network element and passing through the first core network element. The second satellite refers to the target satellite for the handover. The first network element sends a first session modification request to the first core network element, and the first session modification request instructs the first core network element to add a transmission path to the second core network element; The first network element establishes a transmission path between the second core network element and the first terminal device. The transmission path refers to a newly added PDU session with the second core network element as the anchor point. After the first terminal device enters the second communication state, the first network element deletes the connection between the first terminal device and the first core network element; During the process of the first terminal device and the second terminal device transitioning from the second communication state to the third communication state, the first network element establishes a transmission path between the second core network element and the second terminal device. The transmission path refers to a newly added PDU session with the second core network element as the anchor point. The third communication state refers to the first terminal device communicating with the second terminal device through the PDU session anchored at the second core network element. After the second terminal device enters the third communication state, the first network element deletes the connection between the second terminal device and the first core network element.

19. The method according to claim 18, characterized in that, During the process of the first terminal device and the second terminal device transitioning from the first communication state to the second communication state, the first terminal device simultaneously communicates with the second terminal device through a PDU session anchored at the first core network element and a PDU session anchored at the second core network element and passing through the first core network element. The Internet Protocol IP address allocated by the second core network element to the first terminal device is different from the IP address allocated by the first core network element to the first terminal device.

20. The method according to claim 18, characterized in that, During the process of the first terminal device and the second terminal device transitioning from the second communication state to the third communication state, the second terminal device simultaneously communicates with the first terminal device through a PDU session anchored at the first core network element and passing through the second core network element, as well as a PDU session anchored at the second core network element. The Internet Protocol IP address allocated by the second core network element to the second terminal device is different from the IP address allocated by the first core network element to the second terminal device.

21. A communication method, characterized in that, The method includes: During the transition from a first communication state to a second communication state between the first terminal device and the second terminal device, the first core network element in the first satellite receives a first session modification request sent by the first network element. The first session modification request instructs the first core network element to add a transmission path to the second core network element in the second satellite. The first communication state refers to the first terminal device communicating directly with the second terminal device through a PDU session anchored at the first core network element. The second communication state refers to the first terminal device communicating with the second terminal device through a PDU session anchored at the second core network element and passing through the first core network element. The second satellite refers to the target satellite for the handover. According to the first session modification request, the first core network element adds a transmission path to the second core network element locally. The second core network element and the first terminal device add a new transmission path. The transmission path refers to the PDU session added with the second core network element as the anchor point. After the first terminal device enters the second communication state, the connection between the first terminal device and the first core network element is disconnected. During the process of the first terminal device and the second terminal device transitioning from the second communication state to the third communication state, a new transmission path is added between the second core network element and the second terminal device. The transmission path refers to a new PDU session anchored by the second core network element. After the second terminal device enters the third communication state, the connection between the second terminal device and the first core network element is disconnected.

22. The method according to claim 21, characterized in that, During the process of the first terminal device and the second terminal device transitioning from the first communication state to the second communication state, the first terminal device simultaneously communicates with the second terminal device through a PDU session anchored at the first core network element and a PDU session anchored at the second core network element and passing through the first core network element. The Internet Protocol IP address allocated by the second core network element to the first terminal device is different from the IP address allocated by the first core network element to the first terminal device.

23. The method according to claim 21, characterized in that, During the process of the first terminal device and the second terminal device transitioning from the second communication state to the third communication state, the second terminal device simultaneously communicates with the first terminal device through a PDU session anchored at the first core network element and passing through the second core network element, as well as a PDU session anchored at the second core network element. The Internet Protocol IP address allocated by the second core network element to the second terminal device is different from the IP address allocated by the first core network element to the second terminal device.

24. A communication device, characterized in that, The device includes at least one processor coupled to a memory storing a program or instructions, the processor executing the program or instructions to cause the device to perform the communication method as described in any one of claims 1 to 23.

25. A computer-readable storage medium having a computer program or instructions stored thereon, characterized in that, When the computer program or instructions are executed, they cause the computer to perform the method as described in any one of claims 1 to 23.

26. A communication system, characterized in that, Includes the communication device as described in claim 24.

27. A chip system, characterized in that, It includes one or more processors, said one or more processors being configured to retrieve and execute instructions stored in memory, such that the method as claimed in any one of claims 1 to 23 is performed.

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