Communication method and apparatus

Abstract

The present application relates to the technical field of communications. Provided are a communication method and apparatus, which are used for solving the problem of a relatively long waiting delay of a terminal due to a discontinuous access link or feed link in a storage and forward scenario of non-terrestrial network communication. The method comprises: on the basis of ephemeris information and / or information of a terminal, determining a second satellite; and migrating context information corresponding to the terminal from a first satellite to the second satellite. By means of migrating context information of a terminal onto a second satellite which can more quickly serve the terminal, the waiting delay of the terminal can be reduced, and the communication efficiency can be improved.

Description

Communication method and device

[0001] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office on March 25, 2024, with application number 202410350645.1 and application name “A Communication Method and Device”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of communication technology, and in particular to a communication method and device. Background Art

[0003] Non-terrestrial network (NTN) communications include transparent forwarding and regenerative forwarding communication (or regenerative payload) scenarios. In the transparent forwarding scenario, the satellite directly forwards the received signal without performing any data processing. In the regenerative forwarding scenario, the satellite can process the received signal before forwarding it. In this case, the satellite can carry some or all functions of the access network (such as a base station) and / or the core network, and the gateway can be used to connect the satellite to the terrestrial network (such as some or all functions of the core network). The connection between the terminal and the satellite can be called an access connection, and the connection between the satellite and the gateway can be called a feed connection. The access connection and / or feed connection may be disconnected for a period of time, which is called a discontinuous feed scenario.

[0004] For the discontinuous feeding scenario in regeneration forwarding, also known as the store and forward (S&F) scenario, the base station and / or core network deployed on the satellite can receive and store the uplink data of the terminal when the access connection is available; when the feeding connection is available, forward the stored uplink data of the terminal to the core network, and optionally receive and store the downlink data to be sent to the terminal from the core network.

[0005] As can be seen, in an S&F scenario, if only one satellite provides access to a terminal, the satellite's service latency may be long. For example, depending on the satellite's ephemeris information, it may take several days or even a week to provide service to the terminal. In this S&F scenario, how to support multiple satellites to provide service to the terminal, allowing the terminal to access other satellites that provide service faster and reduce the terminal's waiting latency, is an urgent problem to be solved in this application. Summary of the Invention

[0006] The present application provides a communication method and apparatus for solving the problem of long terminal waiting delay in the store-and-forward (S&F) scenario of NTN communication, thereby improving user experience.

[0007] To achieve the above objectives, this application adopts the following technical solutions:

[0008] In a first aspect, a communication method is provided. The method can be executed by a network device or by a module (such as a chip or circuit) of the network device. For example, the network device can be a first satellite or a network device deployed on the ground. The method includes: determining a second satellite based on ephemeris information and / or terminal information; and migrating context information corresponding to the terminal from the first satellite to the second satellite. The context information corresponding to the terminal refers to relevant information used to maintain a communication connection between the network and the terminal. For example, the context information corresponding to the terminal may include at least one of the following information: an identifier assigned to the terminal by the first satellite, an identifier assigned to the terminal by the base station, an identifier assigned to the terminal by a control plane function of the core network, session-related information corresponding to the terminal, subscription information of the terminal, capability information of the terminal, a tracking area identifier corresponding to the terminal, an identifier of the first satellite, etc.

[0009] In the above embodiment, the network device in the S&F scenario can determine another satellite that can provide services to the terminal faster based on the satellite's ephemeris information or the terminal's information, and trigger the migration of the terminal's context information from the first satellite to the second satellite, thereby reducing the terminal's waiting delay and improving communication efficiency and user experience.

[0010] In one embodiment, the first satellite operates in a regenerative forwarding mode and / or a discontinuous feed connection mode. The regenerative forwarding mode means that the satellite has signal processing capabilities and can process received signals before forwarding them. In this case, the satellite can carry some or all functions of an access network (e.g., a base station) and / or a core network.

[0011] In the above-described implementation, in the S&F scenario, the satellites operate in regenerative forwarding mode. As the first satellite operates, the access connection between the terminal and the first satellite is disconnected, and the feeder connection between the first satellite and the gateway is restored. As the second satellite operates, it can provide access services to the terminal faster than the first satellite. The network can then trigger the migration of the terminal's context information from the first satellite to the second satellite. The terminal can then establish a connection with the second satellite, thereby reducing terminal latency and improving communication efficiency and user experience.

[0012] In one embodiment, the method further includes: a second satellite serving the terminal, or the second satellite sending data or signaling to the terminal, or the terminal sending data or signaling to the second satellite. The network device migrates the terminal's context information from the first satellite to the second satellite. Subsequently, the terminal can establish a connection with the second satellite, the second satellite serves the terminal, and the second satellite transmits uplink and downlink data with the terminal, thereby reducing the terminal's waiting delay.

[0013] In one embodiment, before determining the second satellite, the method further includes: the first satellite serving the terminal, or the first satellite sending data or signaling to the terminal, or the terminal sending data or signaling to the first satellite. When an access link between the first satellite and the terminal is available, the first satellite serves the terminal, and the first satellite transmits uplink and downlink data with the terminal.

[0014] In one embodiment, before determining the second satellite, the method further includes: the first satellite generating or obtaining context information of the terminal. When the access link between the first satellite and the terminal is available, the first satellite may generate or obtain the context information of the terminal. Subsequently, the network device may determine to migrate the context information of the terminal to the second satellite, thereby restoring service for the terminal based on the context information and improving communication efficiency of the terminal.

[0015] In one embodiment, determining the second satellite includes determining the second satellite based on one or more of the following: ephemeris information, information about the terminal, status information of the first satellite and / or the second satellite, and a terminal context migration policy. The satellite status information indicates the operating status of the satellite. Exemplarily, the satellite status information may include whether the satellite is in an out-of-service or in-service state, or in a powered-off, powered-on, or online state, or in a faulty state. The terminal context migration policy refers to a terminal context migration policy that a network device can trigger based on the terminal context migration policy. For example, the terminal context migration policy can serve as a judgment condition for the network device to determine triggering context migration.

[0016] In the above implementation, the network device can flexibly determine the second satellite that can serve the terminal faster based on the above information, thereby triggering the migration of the terminal's context information from the first satellite to the second satellite. The terminal can subsequently establish a connection with the second satellite, which can reduce the terminal's waiting delay, improve communication efficiency and increase the flexibility of context migration.

[0017] In one embodiment, the method further includes: determining at least one of the following based on the ephemeris information and / or the information of the terminal: the waiting time for the first satellite to serve the terminal, the waiting time for the second satellite to serve the terminal, and the difference between the waiting times for the first satellite and the second satellite to serve the terminal.

[0018] In the above embodiment, the network device can determine the above information based on the ephemeris information and / or the terminal information, so as to flexibly determine the second satellite that can serve the terminal faster, triggering the migration of the terminal's context information from the first satellite to the second satellite, which can reduce the terminal's waiting delay, improve communication efficiency and increase the flexibility of context migration.

[0019] In one embodiment, migrating the context information corresponding to the terminal from the first satellite to the second satellite includes: according to a terminal context migration strategy, if the waiting time for the first satellite to serve the terminal is greater than or equal to a first threshold, migrating the context information corresponding to the terminal from the first satellite to the second satellite; wherein the terminal context migration strategy includes the first threshold; and / or, according to the terminal context migration strategy, if the waiting time for the second satellite to serve the terminal is less than the waiting time for the first satellite to serve the terminal, migrating the context information corresponding to the terminal from the first satellite to the second satellite.

[0020] In the above embodiment, the context migration strategy is configured to include a first threshold value, which is used to trigger context migration when the network device determines that the current waiting time for the first satellite to serve the terminal reaches or exceeds the maximum waiting time that the terminal can tolerate, such as the first threshold value; migrating the terminal's context information from the first satellite to the second satellite that can serve the terminal more quickly can reduce the terminal's waiting delay, improve communication efficiency, and increase the flexibility of context migration.

[0021] In one embodiment, the waiting time for the terminal to be served by the second satellite is shorter than the waiting time for the terminal to be served by the first satellite, including: a difference between the waiting time for the terminal to be served by the second satellite and the waiting time for the terminal to be served by the first satellite is greater than or equal to a second threshold; wherein the terminal context migration strategy includes the second threshold.

[0022] In the above embodiment, the context migration strategy is configured to include a second threshold value, which is used to trigger context migration when it is determined that the waiting time of the second satellite service terminal is less than the waiting time of the current first satellite service terminal; or trigger context migration when it is determined that the difference between the waiting time of the first satellite service terminal and the waiting time of the second satellite service terminal is greater than or equal to a delay difference that the terminal can tolerate, such as the second threshold value. Migrating the terminal's context information from the first satellite to the second satellite that can serve the terminal more quickly can reduce the terminal's waiting delay, improve communication efficiency, and enhance the flexibility of context migration.

[0023] In one embodiment, the first threshold includes at least one of the following: the delay that the terminal can tolerate or the configured maximum delay, the delay that the first service of the terminal can tolerate or the configured maximum delay, and the maximum delay that can be tolerated by any terminal and / or service to trigger context migration.

[0024] In the above implementation, the configuration of the first threshold is flexible. It can be a unified first threshold configured for any terminal, or a specific service or multiple services can be configured with a unified first threshold, or different terminals can be configured with different first thresholds, or different services of different terminals can be configured with corresponding different first thresholds, etc. The flexibility of the relevant thresholds in the network configuration migration strategy is high, which is convenient for setting according to different service needs and improving communication efficiency.

[0025] In one embodiment, the second threshold is the minimum delay difference between the terminal and different satellites that triggers the migration of the terminal context information to establish a connection, and the second threshold includes at least one of the following: the delay difference that the terminal can tolerate or the configured maximum delay difference, the delay difference that the terminal's first service can tolerate or the configured maximum delay difference, and the maximum delay difference that any terminal and / or service triggers context migration or can tolerate.

[0026] In the above implementation, the configuration of the second threshold is flexible. It can be a unified second threshold configured for any terminal, or a specific service or multiple services can be configured with a unified second threshold, or different terminals can be configured with different second thresholds, or different services of different terminals can be configured with corresponding different second thresholds, etc. The flexibility of the relevant thresholds in the network configuration migration strategy is high, which is convenient for setting according to different business needs and improving communication efficiency.

[0027] In one embodiment, the method further includes: pre-configuring the migration strategy of the terminal context; or obtaining the migration strategy of the terminal context from a first device, wherein the first device is a home user server, a unified data management function, a policy and charging rules function, a policy control function or an application function.

[0028] In the above implementation mode, the method of configuring the context migration policy for the network device is flexible. The migration policy of the terminal context can be pre-configured or imported into the network device, or the network device can obtain the migration policy of the terminal context from other network elements. The flexibility of configuring the migration policy is high, which is convenient for configuration or updating according to different business needs, thereby improving communication efficiency.

[0029] In one embodiment, the terminal information includes at least one of the following information: an identifier of the terminal, location information of the terminal, and information about services supported or accessed by the terminal.

[0030] In one embodiment, the context information corresponding to the terminal includes at least one of the following information: a terminal identifier assigned to the terminal by the first satellite, a terminal identifier assigned to the terminal by a control plane function of the core network, session-related information corresponding to the terminal, subscription information of the terminal, capability information of the terminal, a tracking area identifier corresponding to the terminal, and an identifier of the first satellite. The identifier assigned to the terminal by the satellite may be an inactive radio network temporary identifier (I-RNTI), a paging radio network temporary identifier (P-RNTI), a cell-radio network temporary identifier (C-RNTI), or a temporary mobile subscriber identity (TMSI). The identifier assigned to the terminal by the core network may be a GUTI, TMSI, 5G-GUTI, or 5G-S-TMSI assigned to the terminal by an MME / AMF network element. The capability information of the terminal refers to information indicating the capabilities or functions of the terminal device. The satellite identifier is used to uniquely indicate the satellite, such as the first satellite. For example, the satellite identifier may be an identifier of the RAN deployed on the satellite. For example, the RAN identifier may be a cell identity, an eNB / gNB ID, or an (NG-)RAN ID.

[0031] In one embodiment, the method is applied to a network device deployed on the ground.

[0032] In one embodiment, the method is applied to a control plane functional network element of a core network in a terrestrial network, or part of the functions of a base station.

[0033] In the above-mentioned embodiment, network equipment deployed on the ground, such as a core network element or a base station in a ground network, can trigger the context migration of the terminal, thereby migrating the context information of the terminal from a first satellite to a second satellite that can serve the terminal faster, thereby reducing the waiting delay of the terminal, improving communication efficiency and increasing the flexibility of context migration.

[0034] In one embodiment, before migrating the context information corresponding to the terminal from the first satellite to the second satellite, the method further includes: receiving a first message, the first message including the downlink data corresponding to the terminal, or the first message being used to indicate that the downlink data corresponding to the terminal arrives through a user plane function. That is, the network device may trigger context migration when receiving downlink data from the terminal; or the network device may trigger context migration when receiving a message indicating that the downlink data corresponding to the terminal arrives through a user plane function. When the downlink data of the terminal arrives through the user plane function, the service gateway / user plane function network element may first cache the downlink data of the terminal, and may notify the control plane through the first message that the terminal has data arriving, so that after a period of time, the control plane may instruct the service gateway / user plane function network element to send the cached downlink data to the second satellite, and send the downlink data to the corresponding terminal through the second satellite. Alternatively, the service gateway / user plane function network element directly sends the data to the control plane, the control plane caches the downlink data, and the control plane may send the cached downlink data to the second satellite, and send the downlink data to the corresponding terminal through the second satellite.

[0035] In the above embodiment, when downlink data arrives at the terminal, the ground network equipment can trigger context migration and migrate the terminal's context information from the first satellite to the second satellite that can serve the terminal faster, thereby reducing the terminal's waiting delay and improving the terminal's communication efficiency and user experience.

[0036] In one embodiment, migrating the context information corresponding to the terminal from the first satellite to the second satellite includes: sending a second message to the first satellite to instruct the first satellite to send the context information corresponding to the terminal; receiving a response message from the first satellite, the response message including the context information corresponding to the terminal; and sending the context information corresponding to the terminal to the second satellite.

[0037] In the above embodiment, the network device can obtain the context information of the terminal from the first satellite and forward the obtained context information to the corresponding second satellite, thereby realizing the context migration of the terminal, so that when the access connection between the second satellite and the terminal is available, the service is restored for the terminal according to the context information, thereby reducing the communication delay of the terminal and improving the communication efficiency.

[0038] In one embodiment, migrating the context information corresponding to the terminal from the first satellite to the second satellite includes: sending a third message to the first satellite, where the third message includes an identifier of the second satellite and is used to instruct the first satellite to send the context information corresponding to the terminal to the second satellite.

[0039] In the above-mentioned embodiment, the network device can implement the context migration of the terminal by instructing the first satellite to send the context information of the terminal to the corresponding second satellite, so that when the access connection between the second satellite and the terminal is available, the service is restored for the terminal according to the context information, thereby reducing the communication delay of the terminal and improving the communication efficiency.

[0040] In one embodiment, migrating the context information corresponding to the terminal from the first satellite to the second satellite includes: sending a fourth message to the second satellite, where the fourth message includes an identifier of the first satellite and is used to instruct the second satellite to obtain the context information corresponding to the terminal from the first satellite.

[0041] In the above-mentioned embodiment, the network device can implement the context migration of the terminal by instructing the second satellite to request the first satellite to obtain the context information of the terminal, so that when the access connection between the second satellite and the terminal is available, the service is restored for the terminal according to the context information, thereby reducing the communication delay of the terminal and improving the communication efficiency.

[0042] In one embodiment, if no inter-satellite link exists between the first satellite and the second satellite, the method further includes: receiving a response message to the third message, the response message including the context information of the terminal; and sending the context information corresponding to the terminal to the second satellite.

[0043] In the above embodiment, the first satellite can send the context information of the terminal to the second satellite via an inter-satellite link. If there is no inter-satellite link between the first satellite and the second satellite, the context information can be forwarded through a network device to achieve context migration, thereby reducing the communication delay of the terminal and improving the flexibility of context migration.

[0044] In one embodiment, if there is no inter-satellite link between the first satellite and the second satellite, the method further includes: receiving a response message to the fourth message, the response message indicating that there is no inter-satellite link or indicating that the context information of the terminal is obtained from the first satellite; sending a fifth message to the first satellite, used to instruct the first satellite to send the context information corresponding to the terminal; receiving a response message from the first satellite, the response message including the context information corresponding to the terminal; and sending the context information corresponding to the terminal to the second satellite.

[0045] In one embodiment, the method is applied to the first satellite.

[0046] In one embodiment, the method is applied to an access network device or a core network element on board a satellite.

[0047] In the above-mentioned embodiment, the network equipment deployed on the satellite, such as the core network element or base station deployed on the satellite, can trigger the context migration of the terminal, thereby migrating the context information of the terminal from the first satellite to the second satellite that can serve the terminal faster, which can reduce the waiting delay of the terminal, improve communication efficiency and increase the flexibility of context migration.

[0048] In one embodiment, migrating the context information corresponding to the terminal from the first satellite to the second satellite includes: sending the context information corresponding to the terminal to the second satellite.

[0049] In the above implementation, the first satellite may send the context information of the terminal to the second satellite via an inter-satellite link, thereby reducing the communication delay of the terminal and improving the flexibility of context migration.

[0050] In one embodiment, migrating the context information corresponding to the terminal from the first satellite to the second satellite includes: sending a sixth message to a second device, the sixth message including the context information corresponding to the terminal, the sixth message being used to indicate the migration of the context information corresponding to the terminal, and the second device being a network device deployed on the ground.

[0051] In one implementation, the sixth message includes an identifier of the second satellite, and the sixth message is used to instruct to send the context information corresponding to the terminal to the second satellite.

[0052] In the above implementation, if there is no inter-satellite link between the first satellite and the second satellite, forwarding can be performed through a network device to implement context migration, thereby reducing the communication delay of the terminal and improving the flexibility of context migration.

[0053] In one embodiment, before migrating the context information corresponding to the terminal from the first satellite to the second satellite, the method further includes: sending a seventh message, where the seventh message includes uplink data or uplink signaling corresponding to the terminal.

[0054] In the above embodiment, the network device on the satellite can trigger context migration when the terminal has uplink data or downlink data, and migrate the terminal's context information from the first satellite to the second satellite that can serve the terminal faster, which can reduce the terminal's waiting delay and improve the terminal's communication efficiency and user experience.

[0055] In a second aspect, a communication device is provided for implementing the above-mentioned method. The communication device may be the network device described in the first aspect, or a node or device comprising the above-mentioned network device, or a module in the above-mentioned network device, such as a chip, chip system, or circuit, or a logical node, logical module, or software that can implement some or all of the functions. For example, the network device may be a satellite, a base station deployed on a satellite, a core network element or function deployed on a satellite, a base station deployed on the ground, or a core network element or function deployed on the ground.

[0056] The communication device includes modules, units, or means corresponding to the above-mentioned method, which can be implemented by hardware, software, or hardware executing corresponding software implementation. The hardware or software includes one or more modules or units corresponding to the above-mentioned functions.

[0057] In conjunction with the second aspect above, in one possible implementation, the communication device may include a processing module and a transceiver module. The processing module may be configured to implement the processing functions described in any of the above aspects and any possible implementations thereof. The processing module may, for example, be a processor. The transceiver module, also referred to as a transceiver unit, may be configured to implement the transmitting and / or receiving functions described in any of the above aspects and any possible implementations thereof. The transceiver module may be comprised of a transceiver circuit, a transceiver, a transceiver, or a communication interface.

[0058] In combination with the above second aspect, in a possible implementation, the transceiver module includes a sending module and a receiving module, which are respectively used to implement the sending and receiving functions in any of the above aspects and any possible implementations thereof.

[0059] In a third aspect, a communication device is provided, comprising: a processor; the processor is configured to be coupled to a memory, read instructions from the memory, and then execute the method described in any of the above aspects according to the instructions. The communication device may be the network device described in the first aspect, or a node or device comprising the network device, or a module within the network device, such as a chip, chip system, or circuit, or a logical node, logic module, or software capable of implementing some or all of the functions.

[0060] In combination with the third aspect above, in a possible implementation, the communication device further includes a memory, which is used to store necessary program instructions and data.

[0061] In conjunction with the third aspect above, in one possible implementation, the communication device is a chip or a chip system. Optionally, when the communication device is a chip system, it can be composed of a chip or include a chip and other discrete devices.

[0062] In a fourth aspect, a communication device is provided, comprising: a processor and an interface circuit; the interface circuit is configured to receive a computer program or instruction and transmit it to the processor; and the processor is configured to execute the computer program or instruction, so that the communication device performs the method described in any of the above aspects. The communication device may be the network device described in the first aspect, or a node or device comprising the network device, or a module in the network device, such as a chip, chip system, or circuit, or a logical node, logical module, or software capable of implementing some or all of the functions.

[0063] In conjunction with the fourth aspect above, in one possible implementation, the communication device is a chip or a chip system. Optionally, when the communication device is a chip system, it can be composed of a chip or include a chip and other discrete devices.

[0064] In a fifth aspect, a computer-readable storage medium is provided, wherein instructions are stored in the computer-readable storage medium. When the computer-readable storage medium is run on a computer, the computer can execute the method described in any one of the above aspects.

[0065] In a sixth aspect, a computer program product comprising instructions is provided, which, when executed on a computer, enables the computer to execute the method described in any one of the above aspects.

[0066] Among them, the technical effects brought about by any possible implementation method in the second to sixth aspects can refer to the technical effects brought about by different possible implementation methods in the above-mentioned first aspect, and will not be repeated here.

[0067] It is understandable that, provided that the solutions are not contradictory, the solutions in each aspect can be combined. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] FIG1 is a schematic diagram of the architecture of a communication system provided in an embodiment of the present application;

[0069] FIG2 is a schematic diagram of the architecture of another communication system provided in an embodiment of the present application;

[0070] FIG3 is a schematic diagram of the architecture of another communication system provided in an embodiment of the present application;

[0071] FIG4a is a schematic diagram of the architecture of another communication system provided in an embodiment of the present application;

[0072] FIG4 b is a schematic diagram of the architecture of another communication system provided in an embodiment of the present application;

[0073] FIG4c is a schematic diagram of the architecture of another communication system provided in an embodiment of the present application;

[0074] FIG5 is a schematic diagram of a communication scenario provided in an embodiment of the present application;

[0075] FIG6 is a flow chart of a communication method provided in an embodiment of the present application;

[0076] FIG7 is a flow chart of another communication method provided in an embodiment of the present application;

[0077] FIG8 is a flow chart of another communication method provided in an embodiment of the present application;

[0078] FIG9 is a schematic structural diagram of a communication device provided in an embodiment of the present application;

[0079] FIG10 is a schematic diagram of the structure of another communication device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0080] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application.

[0081] First, a brief introduction to the implementation environment and application scenarios of the embodiments of the present application is given.

[0082] The technical solutions of the embodiments of the present application can be applied to the NTN communication system or the satellite overall network architecture (satellite overall architecture, SAT_ARCH). The application scenarios of the present application will be described below with reference to the accompanying drawings, taking the NTN communication system as an example.

[0083] NTN communication is a deployment scenario of non-terrestrial networks including satellite systems or high altitude platform stations (HAPS), which uses the wide-area coverage capabilities of non-terrestrial network devices such as satellites to provide wireless communication services. The non-terrestrial network devices described in this application can also be referred to as aerial network devices, such as satellites, HAPS devices, drone devices, etc., which can be deployed in the air, without limitation. In this application, satellites are used as an example of aerial network devices.

[0084] To facilitate understanding of the embodiments of the present application, a communication system applicable to the embodiments of the present application will first be described with reference to FIG1 . FIG1 shows a schematic diagram of the architecture of an NTN communication system applicable to the embodiments of the present application. As shown in FIG1 , the communication system may include at least one non-terrestrial network device such as a satellite or HAPS, such as the satellite shown in FIG1 ; the communication system may also include at least one terminal device, such as the terminal shown in FIG1 .

[0085] As shown in FIG1 , for example, the satellite may be an artificial earth satellite providing radio communication services. The satellite and the terminal may communicate via a wireless link, and the satellite may provide communication services to the terminal, such as transmitting telephone, telegraph, fax, data, and television information.

[0086] In addition, the communication system may also include a gateway station, which is mainly used to connect the satellite and the ground network and can be maintained by the satellite operator. Specifically, the satellite operator can maintain the physical connection between the satellite and the ground terminal, and between the satellite and the gateway station.

[0087] Among them, satellite includes transparent forwarding scenario and regeneration forwarding scenario.

[0088] In transparent forwarding scenarios, satellites can act as relays, transparently forwarding data between ground base stations and terminals. They can also forward signals from other network devices or terminals, enhancing ground network coverage. As shown in Figure 2, terminals establish wireless communications with satellites over the air interface. Transparent forwarding between the terminal and base station is achieved through the satellite, enabling communication with the core network and data networks.

[0089] The base station may include an evolved network base station (E-UTRAN NodeB (eNodeB)) of a fourth generation mobile communication (4G) network, or a 5G NR (new radio) base station (gNodeB) of a fifth generation mobile communication (5G) network. The core network element may include a mobility management entity (MME) of a fourth generation mobile communication network, or an access and mobility management function (AMF) of a fifth generation mobile communication network, and may also include other core network functions or network elements, such as a policy and charging rule function (PCRF) network element, a policy control function (PCF) network element, or a session management function (SMF) network element, etc., which is not limited in this application.

[0090] It should be noted that the above-mentioned base stations, core network elements and other devices may also be devices in future mobile networks, such as base stations and core network elements in the sixth generation mobile communication (6G), including core network elements for mobility management, etc. The 4G and 5G devices used in the embodiments of this application are only used as examples, and this application does not limit the applicable functional entities.

[0091] As shown in Figure 2, the interface between the base station and the MME can be called the S1 interface, and the interface between the base station and the AMF can be called the NG interface.

[0092] When the satellite operates in transparent forwarding mode, as shown in Figure 2, the satellite can serve as a relay forwarding device between the gateway and the terminal, and is used to forward communication signals between the gateway and the terminal.

[0093] Alternatively, in another embodiment, when the satellite operates in regenerative forwarding mode, the satellite has signal processing capabilities. This can be understood as the satellite in a communication system acting as a network access device, referring to a radio access network (RAN) node (or device), such as a base station, that connects a terminal to a wireless network. For example, a RAN node can be used to provide wireless access services, schedule wireless resources to connected terminal devices, and provide reliable wireless transmission protocols and data encryption protocols. As shown in Figure 3, the terminal establishes wireless communication with the satellite via the air interface, enabling communication with the core network and data network.

[0094] It should be understood that the regenerative forwarding mode in the present application may also be referred to as a regenerative payload mode, regenerative forwarding, or regenerative forwarding communication.

[0095] Examples of RAN nodes include: evolved Node B (gNB), transmission reception point (TRP), evolved Node B (eNB), next generation radio access network (NG-RAN), radio network controller (RNC), Node B (NB), base station controller (BSC), base transceiver station (BTS), home base station (e.g., home evolved NodeB or home Node B, HNB), base band unit (BBU), etc. A RAN node can be a physical RAN or a virtualized RAN, for example, software with all or part of the RAN functionality or logic running on general-purpose hardware, such as a computing card. Furthermore, a RAN node can also be a device that performs base station functions in device-to-device (D2D) communication, vehicle-to-everything (V2X) communication, or machine-type communication (MTC), a satellite, or a base station in future communication systems, without limitation.

[0096] In addition, in a network structure, the access network equipment may include a centralized unit (CU) node and / or a distributed unit (DU) node. In different systems, CU (including CU-CP or CU-UP) or DU may also have different names, but those skilled in the art can understand their meanings. For example, in an open radio access network (O-RAN) system, CU may also be referred to as O-CU (open CU), DU may also be referred to as O-DU, CU-CP may also be referred to as O-CU-CP, and CU-UP may also be referred to as O-CU-UP.

[0097] It should be understood that in the regeneration and forwarding scenario of the present application, the base station deployed on the satellite can be eNB, gNB or NG-RAN without limitation.

[0098] The terminal in the communication system can access the satellite through the air interface and realize communication transmission. The terminal can also be referred to as a terminal device, a user unit, a user station, a mobile station, a mobile station, a remote station, a remote terminal device, a mobile device, a user equipment (UE), a wireless communication device, a user agent or a user device. The terminal device provided in this application can be applied to various communication scenarios, such as V2X communication, MTC, Internet of Things (IOT), virtual reality (VR), augmented reality (AR), industrial control, self-driving, telemedicine, smart grid, smart furniture, smart office, smart wearable, smart transportation, smart city, etc. The terminal device can be a mobile phone, a tablet computer (pad), a computer with wireless transceiver function, a wearable device, aerospace equipment, drone equipment, customer-premises equipment (CPE), fixed wireless access equipment (FWA), etc. In the embodiment of this application, the chip used in the above-mentioned device can also be referred to as a terminal device.

[0099] In addition, when the satellite operates in the regeneration forwarding mode, it can also be divided into regeneration satellites without inter-satellite links and regeneration satellites with inter-satellite links, depending on whether there is an inter-satellite link (ISL) between the satellites. It can be understood that there is an ISL between the satellites, that is, there is an interface between the satellites that can directly exchange data. For example, as shown in Figure 4a, the inter-satellite link can support X2 and Xn interfaces, and satellites can exchange data through the Xn port. In addition, in one scenario, the regeneration satellite can have the DU processing function of the base station, and the satellite can serve as a DU node. As shown in Figure 4a, satellite 1 and satellite 2 can complete the signaling interaction and user data transmission between base station RAN1 and base station RAN2 through the Xn port.

[0100] In one possible implementation, in addition to base stations, other network elements may be deployed on satellites. For example, as shown in Figure 4a, RAN1 and core network elements or portions of their functionality are deployed on satellite 1. Exemplarily, the core network elements or portions of their functionality may be co-located with the base stations on the same satellite, or on different satellites. Optionally, as shown in Figure 4a, the intersatellite link may also support S10 and N14 interfaces to enable interaction between core network elements on satellite 1 and core network elements on satellite 2.

[0101] In this case, the data storage and forwarding on the satellite does not necessarily have to be performed by the base station. One or more core network elements deployed on the satellite can also perform data storage and forwarding, or the base station and the one or more core network elements can jointly perform data storage and forwarding. This application does not limit this.

[0102] In addition, Figure 4b shows some network elements of a 5G network, which may include, for example, SMF, AMF, Application Function (AF), Network Exposure Function (NEF), PCF, Unified Data Management (UDM), User Plane Function (UPF), etc. The following briefly introduces the main functions of each network element.

[0103] SMF: Mainly used for session management, session establishment, UE IP address allocation and / or management, responsible for session establishment, modification, release, and / or quality of service (QoS) control.

[0104] AMF: Mainly responsible for access and mobility management in mobile networks, such as user registration management, connection management, and reachability management. Specific functions include non-access layer signaling termination, registration area management, and access authentication.

[0105] AF: Used by service providers (such as third-party applications, which can be providers other than operators) to indicate requirements to the core network and subscribe to user plane events.

[0106] NEF: Provides 5G core network capability exposure, allowing external network elements to interact with the 5G core network through this network element.

[0107] PCF: Supports unified policy management of network behavior; provides policy rules to the control plane function for execution; and can obtain contract-related information from the UDM or Unified Data Repository (UDR) to make policy decisions.

[0108] UDM: Performs contract management, access authorization, and authentication information generation for users.

[0109] UPF: Mainly responsible for processing user messages, such as forwarding and billing statistics. For example, in a Protocol Data Unit (PDU) session, the UPF that can be directly connected to the data network (DN) through N6 is called the PDU Session Anchor (PSA). The anchor point UPF for local traffic diversion is called the local PDU Session Anchor (L-PSA). The UPF that serves as a diversion point is called a branching point (BP) or an uplink classifier (ULCL).

[0110] For example, Figure 4c shows some network elements in the 4G core network, which may include MME, Serving Gateway (SWG), Public Data Network Gateway (PGW), Policy and Charging Rule Fuection (PCRF), Service Capability Exposure Functio (SCEF) and Home Subscriber Server (HSS), etc.

[0111] The following briefly introduces the main functions of each network element.

[0112] MME: MME is the key control node of the LTE access network and is responsible for the paging of idle mode users and the marking process including retransmission.

[0113] SGW: Local mobility anchor point for inter-eNodeB handover, mobility anchor for inter-3GPP mobility, packet routing and forwarding, transport-level packet marking, and inter-operator charging considerations.

[0114] PGW: Provides transmission between the UE and the Public Data Network (PDN), acting as the PDN gateway. A UE can access multiple PDNs simultaneously through multiple PGWs. The PGW implements control policies, performs user-specific packet filtering, billing, and performs legal monitoring and packet screening.

[0115] PCRF: An architecture defined in the 3GPP standard that implements dynamic QoS policy control and dynamic flow-based charging control, while also providing authorization control based on user subscription information.

[0116] SCEF: used for interaction between operators and service providers.

[0117] HSS: The core database that stores user information in the IP Multimedia Subsystem (IMS) user's home network. It stores IMS user subscription information within the home network and provides a management interface for operators and end users to customize and modify subscription data. Key information stored in the HSS includes IMS user identification, IMS user security context, IMS user routing information, and service subscription information.

[0118] It should be understood that the communication method provided in this application can be applied to different communication networks, such as 4G networks, 5G networks or other networks. The network elements involved in the following embodiments of this application can be replaced with corresponding network elements in the implemented communication network. For example, the actions performed by the MME in the following embodiments can also be performed by the AMF or SMF, and the actions performed by the serving gateway or PGW in the following embodiments can also be performed by the UPF. This application is not limited to this.

[0119] As can be seen from the above, the connection between the terminal and the satellite can be called an access connection or service connection, and the connection between the satellite and the gateway can be called a feeder connection. Due to the motion characteristics of the satellite, the access connection and / or feeder connection may be disconnected for a period of time. The base station and / or core network on the satellite can receive and store the terminal's uplink data when the access connection is available; when the feeder connection is available, it can forward the stored terminal uplink data to the core network, and optionally receive and store downlink data to be sent to the terminal from the core network. When the access connection is available again, the satellite forwards the stored downlink data to the terminal.

[0120] As shown in Figure 5, satellite 1 operates periodically. When a terminal is out of satellite 1's signal coverage, the access connection is disconnected. As satellite 1 operates, the terminal waits for a period of time until the access connection becomes available, allowing the terminal to reconnect to satellite 1. Similarly, when the gateway is out of satellite 1's signal coverage, the feed connection is disconnected, which is a discontinuous feed scenario.

[0121] As can be seen, in the S&F scenario, if only one satellite provides access services to the terminal, the satellite service delay may be long. As shown in Figure 5, based on the ephemeris information of Satellite 1, it may take several days or even a week to provide service to the terminal. Based on this, the present application provides a solution that supports multiple satellites to provide services to the terminal, allowing the terminal to access other satellites that provide services faster, such as Satellite 2 shown in Figure 5, thereby reducing the terminal's waiting delay and improving communication efficiency and user experience.

[0122] Among them, ephemeris information is information about the motion patterns of satellites, such as the satellite's orbital parameters, angular velocity, speed, and other information. Based on this information, communication equipment can calculate the position of the satellite in orbit at each moment. Ephemeris information can be expressed as a simple correspondence, such as the satellite position information corresponding to each moment / time period. Ephemeris information can also be expressed as a satellite coverage map, such as satellite coverage availability information. The satellite coverage map can divide the earth's surface into multiple grid points and display the grid points covered and not covered by the satellite at each moment. For example, the orbital cycle of a satellite orbiting the earth is one hour, with an accuracy of minutes. Each minute, there is a satellite coverage map corresponding to the satellite. Some grid points in the map are bright, and some are dark. The bright grid points represent the grid points that will be covered at the corresponding moment in each cycle of the satellite.

[0123] It should be noted that the ephemeris information involved in this application includes but is not limited to traditional ephemeris information, satellite map information, and gateway deployment information. Among them, traditional ephemeris information includes but is not limited to orbital parameters, or parameters such as the satellite's position calculated based on the orbital parameters. It is understandable that traditional ephemeris information can be used to calculate, predict, depict, or track the time, position, speed, and other states of the satellite's flight. For example, traditional ephemeris information can be 17 bytes of information to represent position (78 bits) and speed (54 bits), or traditional ephemeris information can be 18 bytes of information to represent orbital parameters (such as semi-major axis, range, eccentricity, perigee angle, etc.). Satellite map information can be the range covered by the satellite on the map at each moment. The specific form, content, and name of the ephemeris information are not limited in this application, and reference can be made to the definition of ephemeris information in existing protocols. For example, the ephemeris information in this application can also be referred to as satellite coverage availability information.

[0124] In the prior art, multiple RAN or core network elements can directly obtain the terminal's context information. However, in the aforementioned discontinuous power feed scenario, there may be no intersatellite links between satellites, making it impossible to migrate the terminal's context information between multiple satellites.

[0125] Based on the above problems, the present application provides a communication method and apparatus. In the S&F scenario, the network device can determine another satellite that can provide services to the terminal faster based on the satellite's ephemeris information or the terminal's information, combined with a pre-configured migration strategy, and trigger the migration of the terminal's context information from the first satellite to the second satellite. As shown in Figure 5, as satellite 1 operates, the access connection between the terminal and satellite 1 is disconnected, and the feeder connection between satellite 1 and the gateway is restored. As satellite 2 operates, satellite 2 can provide access services to the terminal faster than satellite 1, then the network can trigger the migration of the terminal's context information from satellite 1 to satellite 2, and the terminal can subsequently establish a connection with satellite 2, thereby reducing the terminal's waiting delay and improving communication efficiency and user experience.

[0126] As shown in Figure 6, the present application provides a communication method applied to a network device, wherein the network device may be the ground network device shown in Figure 4a or satellite 1, hereinafter referred to as the first satellite. Specifically, the network device may be a ground access network device or a base station deployed on the first satellite, or the network device may be a ground core network element / function or a core network element / function deployed on the first satellite, such as the AMF or other network element in Figure 4b, the MME or other network element in Figure 4c, etc., which is not limited in this application.

[0127] The method includes the following steps.

[0128] 601: The network device determines a second satellite according to the ephemeris information and / or the terminal information.

[0129] Before the network device determines the second satellite, the first satellite serves the terminal, or the first satellite sends data or signaling to the terminal, or the terminal sends data or signaling to the first satellite. The second satellite can be a satellite that provides service to the terminal faster than the first satellite.

[0130] In this application, the network device may be any one of an access network device and a core network element, and the network device may be deployed on the first satellite or on the ground. For example, the network device may be a RAN node (such as an eNB or gNB), an MME, an AMF, part of the functions of an MME / AMF deployed on a satellite, part of the functions of an MME / AMF deployed on the ground, a PCRF / PCF network element, or an SMF network element, etc. This application does not limit this.

[0131] In one embodiment, when the network device is deployed on a satellite, the network device may determine the second satellite when an access connection / service connection is available (i.e., a service link is available). When the network device is deployed on the ground, the network device may determine the second satellite when a feeder connection is available.

[0132] In one embodiment, the first satellite operates in a regenerative payload forwarding mode. For example, all or part of the functions of a base station may be deployed on the first satellite, or part or all of the functions of a base station and a core network element may be deployed on the first satellite. This application does not limit the functions deployed on the satellite.

[0133] In one embodiment, before determining the second satellite, the first satellite may generate or obtain context information of the terminal. For example, RAN1 deployed on the first satellite may generate partial context information of the terminal.

[0134] Exemplarily, the RAN1 deployed on the first satellite may establish a communication connection, such as an RRC connection, with the terminal when an access connection with the terminal is available. During the connection establishment process, the RAN1 deployed on the first satellite may generate context information for maintaining the communication connection with the terminal, such as a UE context / RRC context. Alternatively, the RAN1 deployed on the first satellite and part of the MME may establish a communication connection, such as an RRC connection and a NAS connection, with the terminal when an access connection with the terminal is available. During the connection establishment process, the RAN1 deployed on the first satellite and part of the MME may generate context information for maintaining the communication connection with the terminal, such as a UE context / RRC context / NAS context; during the connection establishment process, the RAN1 deployed on the first satellite may generate context information for maintaining the communication connection with the terminal, such as a UE context / RRC context / NAS context.

[0135] Exemplarily, the first satellite may receive and store uplink data of the terminal, including context information of the terminal, when an access connection with the terminal is available.

[0136] In one embodiment, the context information corresponding to the terminal includes at least one of the following information: a UE identifier assigned to the terminal by the first satellite, a UE identifier assigned to the terminal by a control plane function of the core network, session-related information corresponding to the terminal, subscription information of the terminal, capability information of the terminal, a tracking area identifier (TAI) corresponding to the terminal, an identifier of the first satellite, etc.

[0137] It should be understood that in the embodiment of the present application, the context of the terminal may include UE context information used for communication between the RAN and the UE, and optionally, may also include UE context information (UE context) used between the RAN and core network elements.

[0138] As shown in Figure 7, the context information between the RAN and the UE is used for communication between the RAN and the UE. For example, it can be used to suspend or resume a radio resource control (RRC) connection and send RRC messages to each other. The content of the AS context may include any one or more of the following: the UE identifier, the RAN identifier, information used to establish / resume a bearer between the UE and the RAN, and security information.

[0139] The UE identifier may include at least one of the following identifiers: an inactive radio network temporary identifier (I-RNTI), a paging radio network temporary identifier (P-RNTI) or a cell radio network temporary identifier (C-RNTI), an international mobile subscriber identity (IMSI), a subscription permanent identifier (SUPI), a globally unique temporary identity (GUTI / 5G-GUTI), a temporary mobile subscriber identity (TMSI / 5G-S-TMSI), or a combination of at least one of the above identifiers and other information, such as a combination of the above identifier and a RAN identifier, or other identification information that can be used to identify the UE, which can be used to identify the UE when the RAN / core network and the UE communicate.

[0140] The information used to establish / restore the bearer / air interface connection between the UE and the RAN may include any one or more of the following: RRC context, handover preparation information, access layer context (AS-context), access layer configuration (AS-config), physical cell ID, and radio bearer configuration information.

[0141] The security information may include any one or more of the following: UE security capabilities (UE Security Capabilities), access layer security information (AS Security Information).

[0142] The UE context information used between the RAN and the core network elements can be called UE context, which can be used to maintain UE information between the RAN and MME / AMF. The content of this context may include: UE identification, UE PDU session related information, security information, UE capability information, and at least one of TAI.

[0143] The UE identifier can be an identifier assigned by the RAN to the UR, or an identifier assigned by a core network element to the UE. For example, the identifiers assigned by the RAN and the MME / AMF to the UE correspond to the same terminal. When the RAN sends a message to a core network element such as the MME or AMF, it can uniquely identify a terminal by carrying the identifier assigned by the RAN to the UE. When a core network element such as the MME / AMF sends a message to the RAN, it can carry the identifier assigned by the MME / AMF to the UE.

[0144] Exemplarily, the identifier allocated by the RAN to the UE may be: eNB UE S1 interface application protocol (S1 access protocol, S1AP) ID or RAN UE NG interface application protocol (NG access protocol, NGAP) ID, and the identifier allocated by the MME / AMF to the UE may be: MME UE S1AP ID or AMF UE NGAP ID.

[0145] In addition, the subscription information of the terminal can be stored in a unified data management (UDM) network element or a unified data repository (UDR) network element. The definition of the subscription information of the terminal can refer to the relevant description in the 3GPP protocol.

[0146] For example, the terminal context migration policy involved in this application can be stored in the UDM or UDR as the terminal's subscription information, or the terminal context migration policy can be stored in the PCF or UDR as a policy, for example, as the terminal's policy (UE policy), the terminal's session management (SM) policy, etc. The network device can trigger the migration of the terminal context based on the terminal context migration policy. For example, the terminal context migration policy can serve as a judgment condition for the network device to determine the triggering of context migration.

[0147] Exemplarily, the terminal context migration strategy may include triggering context migration when it is determined that the current waiting time of the satellite 1 service terminal reaches or exceeds the maximum waiting time that the terminal can tolerate; or, triggering context migration when it is determined that the waiting time of the satellite 2 service terminal is less than the waiting time of the current satellite 1 service terminal; or, triggering context migration when it is determined that the difference between the waiting time of the satellite 1 service terminal and the waiting time of the satellite 2 service terminal is greater than or equal to the delay difference that the terminal can tolerate; or, triggering context migration when it is determined that the waiting time of the satellite 2 service terminal is less than or equal to the preset time.

[0148] It should be understood that the scenario of the satellite service terminal in this application can be understood as: the satellite signal covers the area where the terminal is located, the access connection between the satellite and the terminal is available, the access connection between the satellite and the terminal is available, the satellite and the terminal establish a connection, or the terminal accesses the satellite, etc. The waiting time (time / time period / timer) of the satellite service terminal can be understood as: the waiting time for the terminal to access the satellite for a certain period of time, the waiting time for the satellite signal to cover the area where the terminal is located again, the waiting time for the satellite access connection / service connection to be available, the waiting time for the satellite to establish a connection with the terminal, or the waiting time for the terminal to access the satellite, etc.

[0149] It should be understood that the above migration strategy is only an exemplary description and is not specifically limited in this application. The following will describe several possible implementations of the network device determining to trigger context migration in conjunction with specific migration strategies, which will not be repeated here.

[0150] In addition, the subscription information of the terminal may further include a terminal identifier stored in the UDM / UDR, for example, a permanent identifier of the terminal, such as an international mobile subscriber identity (IMSI) or a subscription permanent identifier (SUPI).

[0151] In one embodiment, the first satellite operates in a feeder link unavailable mode, or a store and forward mode (S&F scenario).

[0152] That is, when the network device is a device deployed on the ground, the network device can determine the second satellite based on the ephemeris information and / or the information of the terminal when the feed connection is available, and trigger the execution of step 602, that is, migrate the context information corresponding to the terminal from the first satellite to the second satellite. When the network device is a device deployed on a satellite, the network device can determine the second satellite based on the ephemeris information and / or the information of the terminal when the access connection / service connection is available, and trigger the execution of step 602 when the feed connection is available, that is, migrate the context information corresponding to the terminal from the first satellite to the second satellite. Subsequently, the terminal can establish a connection with the second satellite, and the second satellite can provide services to the terminal. For example, after waiting for a period of time, when the second satellite can serve the terminal (the service connection between the second satellite and the terminal is available), the second satellite can establish a connection with the terminal based on the acquired context information corresponding to the terminal.

[0153] In this application, the network device determining the second satellite may specifically refer to the network device determining a network element deployed on the second satellite, such as RAN2 deployed on the second satellite, or an MME deployed on the satellite. Similarly, in step 602, the network device migrating the terminal context from the first satellite to the second satellite refers to migrating the terminal context from a device deployed on the first satellite to a device deployed on the second satellite. The device may be an access network device, a core network element, or any other functional module. This will not be repeated hereafter.

[0154] In one embodiment, the method further includes: pre-configuring a terminal context migration policy on the network device; or, obtaining the terminal context migration policy from a first device, where the first device may be a terminal, a home subscriber server (HSS), a UDM network element, a PCRF network element, a PCF network element, an application server (AS), or an application function (AF). The terminal context migration policy may be stored as subscription and policy information of the terminal, or may be a policy configured on the network device.

[0155] In one embodiment, the network device may determine whether to trigger context migration based on a migration policy, determine a second satellite based on the satellite's ephemeris information and / or terminal information, and migrate the terminal's context information to the second satellite. The order in which the network device determines whether to trigger context migration and determines the second satellite is not limited.

[0156] The terminal information includes at least one of the following information: terminal identification, terminal location information, terminal contract information, and information about services supported or accessed by the terminal.

[0157] In one embodiment, the network device may determine the second satellite based on one or more of the following information: ephemeris information, terminal information, status information of the first satellite and / or the second satellite, and a migration strategy of the terminal context.

[0158] Exemplarily, the network device can determine that the second satellite can provide services based on ephemeris information, such as the ephemeris information of the first and second satellites. For example, if the constellation only provides terminal access services in a certain area, all satellites that can serve that area can serve as the second satellite. Optionally, the first satellite covers the area, the first satellite provides service connections to terminals in the area, and the terminals can access the first satellite in the area for a longer period of time than the second satellite. Optionally, based on a terminal context migration policy, if the time difference between the first and second satellites exceeds a threshold in the terminal context migration policy, the network device can determine the second satellite as the target access device for migrating the terminal context.

[0159] For example, the network device may determine, based on ephemeris information, such as the ephemeris information of the first and second satellites, and the terminal's location information, that the second satellite can provide services for the terminal requesting a specific service or in a specific area. Optionally, the terminal may wait for a certain period of time before accessing the second satellite, or after a period of time, the second satellite may cover the terminal, a service connection between the second satellite and the terminal may be available, or the terminal may access the second satellite. Optionally, the first satellite may cover the terminal, a service connection between the first satellite and the terminal may be available, or the terminal may access the first satellite for a longer period of time than the second satellite. The network device may then determine the second satellite as the target access device for migrating the terminal context.

[0160] In another example, the network device can determine that the terminal is or will be within the signal coverage of the second satellite based on the ephemeris information, such as the ephemeris information of the second satellite and the location information of the terminal, or that the second satellite can cover the terminal after a period of time / the service connection between the second satellite and the terminal is available / the terminal can access the second satellite. The network device can then determine the second satellite as the target access device for migrating the terminal context.

[0161] In another possible example, the network device can determine, based on the status information of the satellite, that the first satellite is or will be out of service or in a power-off state or has failed, and / or the second satellite is or will start service or is in a powered-on or online state. The network device can then determine the second satellite as the target access device for migrating the terminal context.

[0162] In one embodiment, the network device may determine at least one of the following based on ephemeris information and / or terminal information: a waiting time for a first satellite to serve a terminal, a waiting time for a second satellite to serve a terminal, and a difference between the waiting times for the first satellite and the second satellite. Specifically, determining the waiting time for a particular satellite to serve a particular terminal based on ephemeris information and terminal location information, etc., can be found in related technical descriptions and is not further elaborated herein.

[0163] Exemplarily, the terminal context migration strategy may include a first threshold value, which is used to indicate a maximum delay that the terminal can tolerate.

[0164] In one embodiment, the network device determines whether a terminal context migration policy is satisfied, which may specifically include migrating the terminal context information from the first satellite to a second satellite if the waiting time for the first satellite to serve the terminal is greater than or equal to a first threshold. The terminal context migration policy includes the first threshold.

[0165] Exemplarily, the first threshold may specifically be the maximum latency that the terminal can tolerate or the configured maximum latency. That is, the first thresholds may differ for different terminals. Based on the first thresholds corresponding to different terminals, the network device may determine whether the current waiting time of the first satellite service terminal is greater than or equal to the first threshold corresponding to the terminal, thereby determining whether to trigger context migration. For example, the MME / AMF may obtain UE subscription information from the HSS / UDM, which includes the first threshold corresponding to the terminal as the maximum latency value that the terminal can tolerate when using S&F services.

[0166] In another example, the first threshold may be the maximum latency for any terminal to trigger context migration or the maximum tolerable latency. In other words, the network configures a unified first threshold for different terminals. For example, a network element such as an MME / AMF may locally configure the first threshold as the maximum tolerable latency for any terminal using the S&F service.

[0167] In another example, the first threshold may specifically be the maximum delay or the maximum tolerable delay for triggering context migration for one or more services. That is, the network may configure a unified first threshold for any terminal requesting the same service. For example, the MME / SMF may obtain the UE's session subscription information from the HSS / UDM, which includes the first threshold corresponding to the first service, and may also include other services and corresponding thresholds, as the maximum delay value that can be tolerated by any terminal using the first service or using multiple specific services.

[0168] In another example, the first threshold may specifically be the maximum latency or configured maximum latency that can be tolerated by the first service corresponding to the terminal. That is, different terminals may correspond to different first thresholds. Furthermore, the first thresholds may also differ for different services requested by the same terminal. Based on the service currently requested by the terminal, the network device may determine whether the waiting time for the first satellite to serve the terminal is greater than or equal to the maximum latency corresponding to the service, thereby determining whether to trigger context migration.

[0169] In addition, in one embodiment, the network device determines whether the terminal context migration policy is met, which may specifically include: if the waiting time of the second satellite serving the terminal is shorter than the waiting time of the first satellite serving the terminal, the terminal context migration may be triggered to migrate the terminal context information from the first satellite to the second satellite.

[0170] That is, when the network device determines that the second satellite can provide services to the terminal faster, it can trigger terminal context migration to reduce the waiting delay of the terminal.

[0171] Further optionally, in one embodiment, the context migration strategy of the terminal may further include a second threshold, wherein the second threshold is a minimum delay difference between different satellite service terminals that triggers migration of the terminal context information.

[0172] At this point, the network device may determine whether the terminal context migration policy is satisfied, specifically by determining if the difference between the waiting time of the second satellite serving the terminal and the waiting time of the first satellite serving the terminal is greater than or equal to a second threshold. In other words, the network device may determine if the second satellite can provide service to the terminal more quickly and if the difference between the waiting time of the first satellite serving the terminal and the second satellite serving the terminal is greater than or equal to the preset second threshold, thereby triggering context migration.

[0173] In one embodiment, the second threshold includes at least one of the following: the delay difference that the terminal can tolerate or the configured maximum delay difference, the delay difference that the terminal's first service can tolerate or the configured maximum delay difference, the maximum delay difference that any terminal triggers context migration or can tolerate, and the maximum delay difference that any service triggers context migration or can tolerate.

[0174] Similar to the configuration of the aforementioned first threshold, the second threshold can be configured as a unified second threshold for any terminal, or a unified second threshold can be configured for a specific service or multiple services, or different second thresholds can be configured for different terminals, or different services of different terminals can be configured with corresponding second thresholds. This application does not make specific limitations on this.

[0175] In another possible implementation, the network device determines whether a terminal context migration policy is satisfied. Specifically, the network device may migrate the terminal context information from the first satellite to the second satellite if the second satellite's service latency is less than or equal to a third threshold. The terminal context migration policy includes the third threshold. In other words, regardless of the first satellite's latency, if the second satellite can more quickly provide service to the terminal (with the third threshold serving as the second satellite's latency threshold), the terminal context may be migrated to the second satellite.

[0176] Similar to the configuration of the first and second thresholds described above, a unified third threshold may be configured for any terminal, or a unified third threshold may be configured for a specific service or multiple services, or different third thresholds may be configured for different terminals, or different third thresholds may be configured for different services of different terminals. This application does not impose specific limitations on this.

[0177] 602: The network device migrates the context information corresponding to the terminal from the first satellite to the second satellite.

[0178] That is, the network device migrates the context information of the terminal stored on the first satellite to the second satellite, and subsequently the second satellite can establish a connection with the terminal based on the context information of the terminal.

[0179] It should be noted that the following implementation process is applicable to the case where the network device is a device deployed on the first satellite, and the case where the network device is a device deployed on the ground.

[0180] In one embodiment, after the network device completes the context migration, the second satellite serves the terminal, or the second satellite sends data or signaling to the terminal, or the terminal sends data or signaling to the second satellite.

[0181] The network device migrating the context information corresponding to the terminal from the first satellite to the second satellite may specifically include: sending the context information corresponding to the terminal stored on the first satellite to the second satellite.

[0182] In one embodiment, if an inter-satellite link exists between the first satellite and the second satellite, the first satellite may directly send the terminal context information to the second satellite. If no inter-satellite link exists between the first satellite and the second satellite, the first satellite may forward the terminal context information to the second satellite via a core network element.

[0183] It should be understood that, in this application, the process of the network device determining the second satellite in step 601 may not necessarily involve explicit determination. The network device obtaining ephemeris information and / or terminal information, and the process of migrating the terminal's context information from the first satellite to the second satellite in step 602, implicitly include the network device determining the second satellite. Furthermore, this application does not specifically limit the timing of the network device determining the second satellite. The following embodiments describe the decision-making process and migration process of context migration as possible examples.

[0184] In the above implementation, in the store-and-forward (S&F) scenario of NTN communication, the network device can trigger the context migration of the terminal according to the preset terminal context migration strategy, and migrate the terminal's context information to a satellite that can serve the terminal faster, thereby reducing the terminal's waiting delay and improving communication efficiency, further enhancing the user experience.

[0185] The following describes the interaction process for terminal context migration using specific embodiments. In Example 1, the interaction process for terminal context migration is described using a network device deployed on the ground as an example. Specifically, the network device may be a control plane functional element of the core network in a terrestrial network, or a portion of a base station's functionality. Furthermore, in Example 2, the interaction process for terminal context migration is described using a network device deployed on a first satellite as an example. Specifically, the network device may be an access network device or a core network element deployed on the first satellite.

[0186] Example 1

[0187] The network equipment on the ground triggers the context migration of the terminal, wherein the network equipment can be a core network control plane network element deployed on the ground, such as MME, or AMF or other network elements / functions; or, the network equipment can be part of the functions of the base station deployed on the ground. In addition, part of the functions of the base station are deployed on the satellite.

[0188] As shown in FIG7 , taking the network device that triggers terminal context migration as an MME as an example, RAN1 is deployed on the first satellite, and RAN2 is deployed on the second satellite. The communication method includes the following steps.

[0189] 701: The MME determines to trigger context migration based on the ephemeris information and / or terminal information and the migration policy.

[0190] Specifically, the MME determines that the context migration of the terminal needs to be triggered. The specific determination process can refer to any implementation method in the embodiment described in Figure 6 above, and will not be repeated here.

[0191] The MME may determine to migrate the context information of the terminal from the first satellite to the second satellite. Specifically, the context information of the terminal may be migrated from RAN1 of the first satellite to RAN2 of the second satellite.

[0192] In one embodiment, before step 701, the first satellite may establish a connection with the terminal and then release the connection.

[0193] Illustratively, the method may further include the following step 700a.

[0194] 700a: The terminal establishes an RRC connection with the first satellite, releases the RRC connection, and the first satellite saves the context information of the terminal.

[0195] First, the terminal establishes an RRC connection with RAN1 on the first satellite.

[0196] The specific process of establishing the RRC connection may include: the terminal sending an RRC Setup Request message to RAN 1, RAN 1 responding with an RRC Setup Response message to the terminal, and the terminal then sending an RRC Setup Complete message to RAN 1. Thus, the RRC connection between the terminal and RAN 1 is established.

[0197] After the RRC connection is established, the RAN1 of the first satellite stores the context information of the terminal, such as the C-RNTI allocated by the RAN1 to the terminal, which is used to identify the terminal when sending RRC messages to and from the terminal.

[0198] Then, the terminal releases the RRC connection with RAN1 on the first satellite.

[0199] For example, when the terminal has no uplink or downlink data to transmit, or the terminal is outside the signal service range of the first satellite, the terminal releases the RRC connection with RAN 1. When the RRC connection is released, the terminal and RAN 1 each save an RRC context.

[0200] The specific process of releasing the RRC connection may include: RAN 1 sending an RRC release message to the terminal, which may include the I-RNTI allocated to the terminal and an indication information instructing the terminal to cache the RRC context. When the RRC connection is disconnected, RAN 1 allocates the I-RNTI to the terminal as part of the RRC context. Optionally, the terminal responds with an RRC release response message to RAN1, completing the RRC connection release.

[0201] Optionally, the RRC release message may also include a C-RNTI. That is, the RRC context portion of the terminal context information includes an I-RNTI and, optionally, a C-RNTI. The C-RNTI may be deleted or retained when the RRC connection is released.

[0202] Optionally, the method may further include the following step 700b.

[0203] 700b: The MME establishes and saves the context information of the terminal.

[0204] Specifically, RAN 1 on the first satellite sends initial user information (initial UE message) to the MME, which may include context information of the terminal, such as an identifier of the terminal such as eNB UE S1AP ID, and location information of the terminal.

[0205] Then, the MME may reply to the RAN 1 with a downlink NAS transport (Downlink NAS Transport) message through non-access stratum (NAS) signaling, which may include the terminal identifier such as the MME UE S1AP ID.

[0206] At this time, the MME may establish terminal context information between the RAN 1 and the MME, including the UE context part, including the terminal identifier such as the MME UE S1AP ID, and the eNB UE S1AP ID.

[0207] In one embodiment, in an S&F scenario, a network device can also trigger terminal context migration based on the arrival of downlink data. That is, when a network device, such as a core network element (e.g., MME or AMF), determines that downlink data has arrived for a terminal and needs to be sent to the terminal, it can trigger the migration of the terminal's context information to a second satellite that can more quickly serve the terminal, thereby achieving the effect of faster delivery of the downlink data to the terminal.

[0208] Optionally, the method may further include the following step 700c.

[0209] 700c: The serving gateway or PGW sends a first message to the MME, indicating that downlink data has arrived at the terminal.

[0210] The first message may include downlink data corresponding to the terminal, or the first message may be used to indicate that downlink data corresponding to the terminal arrives through a user plane function.

[0211] Optionally, the MME receives a first message from a serving gateway, or receives a first message from a PDN gateway (PGW), wherein the first message includes downlink data corresponding to the terminal, specifically user data forwarded by a control plane of the core network.

[0212] Alternatively, the MME receives a first message from the serving gateway, which includes a notification indicating to the MME that downlink data of the terminal has arrived through a user plane function.

[0213] It should be understood that when downlink data from a terminal arrives via the user plane function, the serving gateway may first buffer the downlink data from the terminal and notify the MME of the arrival of the data. The MME may immediately or after a period of time instruct the serving gateway to send the buffered downlink data to the RAN for ultimate forwarding to the corresponding terminal.

[0214] Next, a terminal context migration process is performed, that is, the terminal context is migrated from the first satellite (such as RAN 1) to the second satellite (such as RAN 2). Specifically, any one of the following optional methods can be used.

[0215] Method 1: The MME obtains the terminal context from the first satellite and sends it to the second satellite.

[0216] 702: The MME sends a second message to the first satellite, requesting context information corresponding to the terminal.

[0217] Specifically, the MME may send a second message to RAN 1 of the first satellite, instructing RAN 1 to provide context information corresponding to the terminal. Optionally, the second message may include indication information indicating the request for context information corresponding to the terminal. RAN 1 may not be aware of the RAN or satellite to which the context of the terminal will be migrated.

[0218] 703: The first satellite sends a response message to the MME, including the context information corresponding to the terminal.

[0219] 704: The MME sends the context information corresponding to the terminal to the second satellite.

[0220] Correspondingly, the MME receives the context information corresponding to the terminal from RAN 1. Then, the MME may send the context information of the terminal to RAN 2.

[0221] Optionally, the timing for the MME to determine the second satellite may be before step 702, or after step 703. This application does not limit this.

[0222] Method 2: The MME instructs the first satellite to send the terminal context to the second satellite.

[0223] 705: The MME sends a third message to the first satellite, including the identifier of the second satellite, instructing the second satellite to send the context information corresponding to the terminal.

[0224] Specifically, the MME may send a third message to RAN 1 of the first satellite, carrying indication information and an identifier of the second satellite or an identifier of RAN2. The indication information is used to instruct the first satellite to send the context information of the terminal to the second satellite.

[0225] In one embodiment, if an intersatellite link exists between the first satellite and the second satellite, step 706 may be performed, and the first satellite may directly send the context information corresponding to the terminal to the second satellite via the intersatellite link. If no intersatellite link exists between the first satellite and the second satellite, steps 706a-707a below are performed.

[0226] 706: The first satellite sends the context information corresponding to the terminal to the second satellite.

[0227] 706a: The first satellite sends a response message to the MME, including the context information corresponding to the terminal.

[0228] 707a: The MME sends the context information corresponding to the terminal to the second satellite.

[0229] That is, if RAN 1 determines that there is no inter-satellite link between RAN 2 and RAN 1, RAN 1 may send the context information of the terminal to MME; after receiving the context information, MEE sends the context information of the terminal to RAN 2.

[0230] Specifically, the first satellite may send a response message to the third message in step 705, carrying the context information of the terminal and the identifier of RAN2; or, the first satellite may send a new message, carrying the context information of the terminal and the identifier of RAN2, to instruct the MME to send the context information of the terminal in the message to RAN2.

[0231] Method 3: The MME instructs the second satellite, and the second satellite obtains the terminal context from the first satellite.

[0232] 707: The MME sends a fourth message to the second satellite, including the identifier of the first satellite, to instruct the second satellite to obtain the context information corresponding to the terminal from the first satellite.

[0233] Specifically, the MME may send a fourth message to RAN 2 of the second satellite, carrying indication information and the identifier of the first satellite or the identifier of RAN1. The indication information is used to instruct the second satellite to request the first satellite to obtain the context information of the terminal.

[0234] In one embodiment, if an intersatellite link exists between the first satellite and the second satellite, step 708 may be performed, and the first satellite may transmit the context information corresponding to the terminal to the second satellite via the intersatellite link. If no intersatellite link exists between the first satellite and the second satellite, steps 708a-711a below are performed.

[0235] 708: The second satellite interacts with the first satellite to obtain context information corresponding to the terminal.

[0236] Specifically, RAN 2 may send instruction information to RAN 1 to instruct RAN 1 to provide context information corresponding to the terminal, and RAN 1 may send the context information corresponding to the terminal to RAN 2 according to the instruction information.

[0237] 708a: The second satellite sends a response message to the fourth message to the MME, indicating that there is no inter-satellite link or instructing to obtain the context information of the terminal from the first satellite.

[0238] Specifically, the response message may indicate information for indicating an inter-satellite link between the first satellite and the second satellite. Then, according to a preset rule, the MME may obtain the context information of the terminal from the first satellite and then send it to the second satellite.

[0239] Alternatively, the response message may include the identifier of the first satellite or the identifier of RAN1, to instruct the MME to obtain the context information of the terminal from the first satellite (RAN1).

[0240] 709a: The MME sends a fifth message to the first satellite, to instruct the first satellite to send the context information corresponding to the terminal.

[0241] 710a: The first satellite sends context information corresponding to the terminal to the MME.

[0242] 711a: The MME sends the context information corresponding to the terminal to the second satellite.

[0243] Correspondingly, the MME receives the context information corresponding to the terminal from the first satellite, and then may send the context information of the terminal to the second satellite according to the instruction of step 7708a.

[0244] In one embodiment, the communication method may further include the following steps.

[0245] 712: The serving gateway sends the downlink data or signaling of the terminal to the second satellite.

[0246] The second satellite or RAN 2 on the second satellite can receive downlink data from the terminal from a serving gateway. Specifically, the serving gateway can directly send the downlink data to RAN 2 via user plane data packets. Alternatively, the serving gateway can send the downlink data to the MME, which then sends the downlink data to RAN 2, such as by sending a Protocol Data Unit (PDU) via control plane NAS signaling, or by sending NAS signaling to carry the downlink data from the terminal.

[0247] 713: The second satellite sends downlink data or signaling to the terminal.

[0248] After a period of time, when the second satellite is able to provide services for the terminal, or the access connection between the second satellite and the terminal is available, or the RRC connection between RAN2 of the second satellite and the terminal is restored / reestablished, the second satellite (RAN 2) sends downlink data or signaling to the terminal.

[0249] In the above implementation, ground-deployed network equipment, such as core network elements, can trigger the context migration of the terminal according to a preset migration strategy, thereby achieving the effect of sending downlink data to the terminal faster, reducing the terminal's waiting delay and improving communication efficiency.

[0250] Example 2

[0251] The satellite triggers the context migration of the terminal, wherein access network equipment such as RAN can be deployed on the satellite. Optionally, some functions of core network elements such as MME, AMF or other network elements / functions can also be deployed on the satellite.

[0252] As shown in FIG8 , the network device triggering terminal context migration is a first satellite as an example. Exemplarily, RAN1 is deployed on the first satellite, and RAN2 is deployed on the second satellite. The ground network device can be a second apparatus, and in this embodiment, an MME is used as an example. The communication method includes the following steps.

[0253] 801: The first satellite determines to trigger context migration based on the ephemeris information and / or the terminal information and the migration strategy.

[0254] Specifically, the first satellite determines that context migration of the terminal needs to be triggered. The specific determination process can refer to any implementation method in the embodiment described in Figure 6 above and is not further described here. Specifically, the first satellite can migrate the context information of the terminal from RAN1 of the first satellite to RAN2 of the second satellite.

[0255] In one embodiment, before step 801, the first satellite may establish a connection with the terminal and then release the connection.

[0256] Illustratively, the method may further include the following step 800a.

[0257] 800a: The terminal establishes an RRC connection with the first satellite, releases the RRC connection, and the first satellite saves the context information of the terminal.

[0258] Refer to the aforementioned step 700a, which will not be repeated here.

[0259] Optionally, the method may further include the following step 800b.

[0260] 800b: The MME establishes and saves the context information of the terminal.

[0261] Refer to the aforementioned step 700b, which will not be repeated here.

[0262] Optionally, the method may further include the following step 800c.

[0263] 800c: The first satellite sends uplink data or signaling to the terminal.

[0264] Optionally, RAN1 on the first satellite may send the seventh message to the MME via the control surface, where the seventh message carries the uplink data or signaling of the terminal; or, RAN1 may send the seventh message to the serving gateway via the user surface, where the seventh message carries the uplink data or signaling of the terminal.

[0265] In one embodiment, the first satellite may trigger context migration of the terminal when executing step 800c. That is, when the first satellite determines that the terminal has uplink data to send, it may select a second satellite that can provide services to the terminal more quickly based on a migration strategy and migrate the terminal's context information to the second satellite, thereby reducing the terminal's waiting delay and improving communication efficiency.

[0266] Next, a terminal context migration process is performed, that is, the terminal context is migrated from the first satellite (such as RAN 1) to the second satellite (such as RAN 2). The migration process can use any one of the following optional methods.

[0267] Method 1: The first satellite sends the context information corresponding to the terminal to the second satellite through an inter-satellite link.

[0268] 802: The first satellite sends context information corresponding to the terminal to the second satellite.

[0269] If the first satellite determines that an inter-satellite link exists between the first satellite and the second satellite, the context information of the terminal may be sent to the second satellite via the inter-satellite link.

[0270] 803: The second satellite sends a response message to the MME.

[0271] Correspondingly, RAN2 on the second satellite receives the terminal context information from RAN1 on the first satellite. Optionally, RAN2 may send a path switch message to the MME, indicating that the terminal context has been migrated to RAN2.

[0272] Method 2: The first satellite sends the context corresponding to the terminal to the network device on the ground, and then the network device on the ground forwards it to the second satellite.

[0273] 804: The first satellite sends the context information corresponding to the terminal to the MME.

[0274] 805: The MME sends the context information corresponding to the terminal to the second satellite.

[0275] Correspondingly, the MME receives the context information of the terminal from the first satellite.

[0276] At this point, the MME is unsure of which satellite to migrate the terminal's context to. The MME can determine, based on the ephemeris information (optionally, based on information such as the terminal's location information, satellite status, and context migration policy), a second satellite that can serve the terminal faster than the first satellite, and then forward the terminal's context information to the second satellite. Specifically, the MME's process for determining the second satellite can refer to the implementation shown in FIG. 6 , and is not further described here.

[0277] Method 3: The first satellite instructs the second satellite to forward the context information of the terminal through the ground network device.

[0278] 806: The first satellite sends a sixth message to the MME, including the context information corresponding to the terminal and the identifier of the second satellite.

[0279] The sixth message may include instruction information, used to instruct the MME to migrate the context information corresponding to the terminal to the second satellite.

[0280] In addition, the sixth message may further include an identifier of the second satellite, used to instruct the MME to send the context information corresponding to the terminal to the second satellite corresponding to the identifier.

[0281] 807: The MME sends the context information corresponding to the terminal to the second satellite.

[0282] Correspondingly, after receiving the sixth message, the MME may send the context information of the terminal carried in the sixth message to the second satellite according to the indication information and the identifier of the second satellite.

[0283] In one embodiment, the communication method may further include the following steps.

[0284] 808: The serving gateway or PGW sends the downlink data or signaling of the terminal to the second satellite.

[0285] The second satellite or RAN 2 on the second satellite can receive downlink data from the terminal from a serving gateway. Specifically, the serving gateway can directly send the downlink data to RAN 2 via user plane data packets. Alternatively, the serving gateway can send the downlink data to the MME, which then sends the downlink data to RAN 2, such as by sending a Protocol Data Unit (PDU) via control plane NAS signaling, or by sending NAS signaling to carry the downlink data from the terminal.

[0286] 809: The second satellite sends downlink data or signaling to the terminal.

[0287] After a period of time, when the second satellite is able to provide services for the terminal, or the access connection between the second satellite and the terminal is available, or the RRC connection between RAN2 of the second satellite and the terminal is restored / reestablished, the second satellite (RAN 2) sends downlink data or signaling to the terminal.

[0288] In the above embodiment, network devices deployed on the satellite, such as base stations, can trigger the context migration of the terminal according to a preset migration strategy, thereby achieving the effect of sending downlink data to the terminal faster, reducing the terminal's waiting delay and improving communication efficiency.

[0289] The various embodiments mentioned above in this application can be combined without limitation if there is no contradiction between the solutions.

[0290] The above mainly introduces the solution provided by this application from the perspective of interaction between various nodes. Accordingly, this application also provides a communication device, which can be the network device in the above method embodiment, or a node or device including the above network device, or a component that can be used for the network device; or, the communication device can be the terminal in the above method embodiment, or a node or device including the above terminal, or a component that can be used for the terminal.

[0291] It is understandable that, in order to implement the above functions, the above communication device includes hardware structures and / or software modules corresponding to the execution of each function. Those skilled in the art should easily realize that, in combination with the units and algorithmic operations of the various examples described in the embodiments disclosed herein, the present application can be implemented in the form of hardware or a combination of hardware and computer software. Whether a function is executed in the form of hardware or computer software driving hardware depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0292] It should be understood that the above description only uses network devices and terminals as examples to describe the interaction between nodes. In fact, the processing performed by the above network devices is not limited to being performed by a single node, and the processing performed by the above terminals is not limited to being performed by a single node.

[0293] The present application can divide the functional modules of the communication device according to the above method example. For example, each functional module can be divided according to each function, or two or more functions can be integrated into one processing module. The above integrated modules can be implemented in the form of hardware or software functional modules. It is understood that the division of modules in this application is schematic and is only a logical functional division. In actual implementation, other division methods may be used.

[0294] For example, in the case of dividing the functional modules in an integrated manner, FIG9 shows a schematic structural diagram of a communication device 900. The communication device 900 includes a processing module 901 and an interface module 902.

[0295] In some embodiments, the communication device 900 may further include a storage module (not shown in FIG. 9 ) for storing program instructions and data.

[0296] Exemplarily, the communication device 900 can be used to implement the functions of a network device. The communication device 900 is, for example, the network device described in the aforementioned embodiments, such as the first satellite or MME.

[0297] The processing module 901 is configured to determine the second satellite according to the ephemeris information and / or the terminal information.

[0298] The interface module 902 is configured to migrate the context information corresponding to the terminal from the first satellite to the second satellite.

[0299] In some embodiments, the processing module 901 is configured to determine the second satellite based on one or more of the following: ephemeris information, information of the terminal, status information of the first satellite and / or the second satellite, and a migration strategy of the terminal context.

[0300] In some embodiments, the processing module 901 is also used to determine at least one of the following based on the ephemeris information and / or the information of the terminal: the waiting time for the first satellite to serve the terminal, the waiting time for the second satellite to serve the terminal, and the difference between the waiting times for the first satellite and the second satellite to serve the terminal.

[0301] In some embodiments, the processing module 901 is used to migrate the context information corresponding to the terminal from the first satellite to the second satellite according to the terminal context migration strategy, if the waiting time for the first satellite to serve the terminal is greater than or equal to a first threshold; wherein the terminal context migration strategy includes the first threshold; and / or, according to the terminal context migration strategy, if the waiting time for the second satellite to serve the terminal is less than the waiting time for the first satellite to serve the terminal, migrate the context information corresponding to the terminal from the first satellite to the second satellite.

[0302] In some embodiments, the waiting time for the terminal to be served by the second satellite is shorter than the waiting time for the terminal to be served by the first satellite, including: a difference between the waiting time for the terminal to be served by the second satellite and the waiting time for the terminal to be served by the first satellite is greater than or equal to a second threshold; wherein the terminal context migration strategy includes the second threshold.

[0303] In some embodiments, the first threshold includes at least one of the following: the delay that the terminal can tolerate or the maximum configured delay, the delay that the first service of the terminal can tolerate or the maximum configured delay, and the maximum delay that any terminal and / or service triggers context migration or can tolerate.

[0304] In some embodiments, the second threshold is the minimum delay difference between the terminal and different satellites that triggers the migration of the terminal context information to establish a connection, and the second threshold includes at least one of the following: the delay difference that the terminal can tolerate or the configured maximum delay difference, the delay difference that the terminal's first service can tolerate or the configured maximum delay difference, and the maximum delay difference that any terminal and / or service triggers context migration or can tolerate.

[0305] In some embodiments, the interface module 902 is used to pre-configure the migration policy of the terminal context; or, obtain the migration policy of the terminal context from a first device, wherein the first device is a home user server, a unified data management function, a policy and charging rules function, a policy control function or an application function.

[0306] In some embodiments, the terminal information includes at least one of the following information: an identification of the terminal, location information of the terminal, and information about services supported or accessed by the terminal.

[0307] In some embodiments, the context information corresponding to the terminal includes at least one of the following information: a terminal identifier assigned to the terminal by the first satellite, a terminal identifier assigned to the terminal by the control plane function of the core network, session-related information corresponding to the terminal, subscription information of the terminal, capability information of the terminal, a tracking area identifier corresponding to the terminal, and an identifier of the first satellite.

[0308] In some embodiments, the method is applied to network equipment deployed on the ground.

[0309] In some embodiments, the interface module 902 is further configured to receive a first message, where the first message includes downlink data corresponding to the terminal, or the first message is configured to indicate that downlink data corresponding to the terminal arrives through a user plane function.

[0310] In some embodiments, the interface module 902 is configured to send a second message to the first satellite, instructing the first satellite to send context information corresponding to the terminal; receive a response message from the first satellite, the response message including the context information corresponding to the terminal; and send the context information corresponding to the terminal to the second satellite.

[0311] In some embodiments, the interface module 902 is configured to send a third message to the first satellite, where the third message includes an identifier of the second satellite and is configured to instruct the first satellite to send context information corresponding to the terminal to the second satellite.

[0312] In some embodiments, the interface module 902 is configured to send a fourth message to the second satellite, where the fourth message includes an identifier of the first satellite and is configured to instruct the second satellite to obtain context information corresponding to the terminal from the first satellite.

[0313] In some embodiments, the interface module 902 is configured to receive a response message to the third message, where the response message includes context information of the terminal; and send the context information corresponding to the terminal to the second satellite.

[0314] In some embodiments, if there is no inter-satellite link between the first satellite and the second satellite, the interface module 902 is used to receive a response message to the fourth message, the response message indicating that there is no inter-satellite link or indicating that the context information of the terminal is obtained from the first satellite; send a fifth message to the first satellite, used to instruct the first satellite to send the context information corresponding to the terminal; receive a response message from the first satellite, the response message including the context information corresponding to the terminal; and send the context information corresponding to the terminal to the second satellite.

[0315] In some embodiments, the method is applied to the first satellite.

[0316] In some embodiments, the interface module 902 is configured to send context information corresponding to the terminal to the second satellite.

[0317] In some embodiments, the interface module 902 is used to send a sixth message to the second device, the sixth message including the context information corresponding to the terminal, the sixth message being used to indicate the migration of the context information corresponding to the terminal, and the second device being a network device deployed on the ground.

[0318] In some embodiments, the sixth message includes an identifier of the second satellite, and the sixth message is used to instruct that the context information corresponding to the terminal be sent to the second satellite.

[0319] In some embodiments, the interface module 902 is configured to send a seventh message, where the seventh message includes uplink data or uplink signaling corresponding to the terminal.

[0320] In a simple embodiment, those skilled in the art may appreciate that the communication device 900 may take the form shown in FIG. 10 .

[0321] 10 is a schematic diagram of the hardware structure of a communication device applicable to an embodiment of the present application. The communication device 100 includes at least one processor 101, a communication circuit 102, a memory 103, and at least one communication interface 104.

[0322] The processor 101 may be a general-purpose central processing unit (CPU), a microprocessor, an application-specific integrated circuit (ASIC), or one or more integrated circuits for controlling the execution of the program of the present application.

[0323] The communication link 102 may include a path for transmitting information between the above components, such as a bus.

[0324] The communication interface 104 uses any transceiver or other device for communicating with other devices or communication networks, such as an Ethernet interface, a RAN interface, a wireless local area network (WLAN) interface, etc.

[0325] The memory 103 can be a read-only memory (ROM) or other types of static storage devices that can store static information and instructions, a random access memory (RAM) or other types of dynamic storage devices that can store information and instructions, or an electrically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM) or other optical disc storage, optical disc storage (including compressed optical disc, laser disc, optical disc, digital versatile disc, Blu-ray disc, etc.), a magnetic disk storage medium or other magnetic storage device, or any other medium that can be used to carry or store the desired program code in the form of an instruction or data structure and can be accessed by a computer, but is not limited thereto. The memory can be independent and connected to the processor via a communication line 102. The memory can also be integrated with the processor. The memory provided in the embodiment of the present application can generally have non-volatility. Among them, the memory 103 is used to store the computer execution instructions involved in executing the solution of the present application, and is controlled by the processor 101 to execute. The processor 101 is used to execute the computer-executable instructions stored in the memory 103, thereby implementing the method provided in the embodiment of the present application.

[0326] Optionally, the computer-executable instructions in the embodiments of the present application may also be referred to as application code, which is not specifically limited in the embodiments of the present application.

[0327] In a specific implementation, as an embodiment, the processor 101 may include one or more CPUs, such as CPU0 and CPU1 in FIG10 .

[0328] In a specific implementation, as an embodiment, the communication device 100 may include multiple processors, such as the processor 101 and the processor 107 in FIG10 . Each of these processors may be a single-core (single-CPU) processor or a multi-core (multi-CPU) processor. The processor herein may refer to one or more devices, circuits, and / or processing cores for processing data (e.g., computer program instructions).

[0329] In a specific implementation, as an embodiment, the communication device 100 may further include an output device 105 and an input device 106. The output device 105 communicates with the processor 101 and can display information in a variety of ways. For example, the output device 105 can be a liquid crystal display (LCD), a light emitting diode (LED) display device, a cathode ray tube (CRT) display device, or a projector. The input device 106 communicates with the processor 101 and can receive user input in a variety of ways. For example, the input device 106 can be a mouse, a keyboard, a touch screen device, or a sensor device.

[0330] The above-mentioned communication device 900 can adopt the structure shown in Figure 10. For example, the processor 101 in Figure 10 can call the computer execution instructions stored in the memory 103 to enable the communication device 900 to execute the method described in the above-mentioned method embodiment.

[0331] Exemplarily, the functions / implementation processes of the processing module 901 in FIG. 9 may be implemented by the processor 101 in FIG. 10 .

[0332] Exemplarily, the functions / implementation processes of the interface module 902 in FIG. 9 may be implemented by the communication interface 104 in FIG. 10 .

[0333] It is understandable that one or more of the above modules or units can be implemented by software, hardware or a combination of the two. When any of the above modules or units is implemented by software, the software exists in the form of computer program instructions and is stored in a memory, and a processor can be used to execute the program instructions and implement the above method flow. The processor can be built into an SoC (system on chip) or an ASIC, or it can be an independent semiconductor chip. In addition to the core used to execute software instructions to perform calculations or processing within the processor, it can further include necessary hardware accelerators, such as field programmable gate arrays (FPGAs), PLDs (programmable logic devices), or logic circuits that implement dedicated logic operations.

[0334] When the above modules or units are implemented in hardware, the hardware can be any one or any combination of a CPU, a microprocessor, a digital signal processing (DSP) chip, a microcontroller unit (MCU), an artificial intelligence processor, an ASIC, a SoC, an FPGA, a PLD, a dedicated digital circuit, a hardware accelerator or a non-integrated discrete device, which can run the necessary software or not rely on the software to execute the above method flow.

[0335] Optionally, the present application also provides a chip system, comprising: at least one processor and an interface, wherein the at least one processor is coupled to a memory via the interface, and when the at least one processor executes a computer program or instruction in the memory, the method in any of the above method embodiments is executed. In one possible implementation, the chip system also includes a memory. Optionally, the chip system can be composed of a chip, or can include a chip and other discrete devices, which is not specifically limited in this application.

[0336] Optionally, the present application also provides a computer-readable storage medium. All or part of the processes in the above-mentioned method embodiments can be completed by a computer program to instruct the relevant hardware. The program can be stored in the above-mentioned computer-readable storage medium. When the program is executed, it can include the processes of the above-mentioned method embodiments. The computer-readable storage medium can be an internal storage unit of the communication device of any of the above-mentioned embodiments, such as a hard disk or memory of the communication device. The above-mentioned computer-readable storage medium can also be an external storage device of the above-mentioned communication device, such as a plug-in hard disk, a smart memory card (smart media card, SMC), a secure digital (secure digital, SD) card, a flash card (flash card), etc. equipped on the above-mentioned communication device. Furthermore, the above-mentioned computer-readable storage medium can also include both the internal storage unit of the above-mentioned communication device and an external storage device. The above-mentioned computer-readable storage medium is used to store the above-mentioned computer program and other programs and data required by the above-mentioned communication device. The above-mentioned computer-readable storage medium can also be used to temporarily store data that has been output or is to be output.

[0337] Optionally, the present application also provides a computer program product. All or part of the processes in the above method embodiments may be completed by a computer program instructing related hardware. The program may be stored in the above computer program product, and when executed, the program may include the processes in the above method embodiments.

[0338] Optionally, the present application also provides a computer instruction. All or part of the process in the above method embodiment can be completed by the computer instruction to instruct the relevant hardware (such as a computer, processor, network device or terminal, etc.). The program can be stored in the above computer-readable storage medium or in the above computer program product.

[0339] Optionally, the present application also provides a communication system, including: the network device and terminal in the above embodiments.

[0340] Through the description of the above implementation methods, technical personnel in the relevant field can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional modules is used as an example. In actual applications, the above-mentioned functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above.

[0341] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are merely schematic. For example, the division of the modules or units is only a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another device, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0342] The units described as separate components may or may not be physically separate, and the components shown as units may be one physical unit or multiple physical units, that is, they may be located in one place or distributed in multiple places. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0343] In addition, the functional units in the various embodiments of the present application may be integrated into a single processing unit, or each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units.

[0344] The above is only a specific embodiment of the present application, but the scope of protection of this application is not limited to this. Any changes or substitutions within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A communication method, characterized in that: The method comprises: determining a second satellite according to the ephemeris information and / or the terminal information; Migrating context information corresponding to the terminal from the first satellite to the second satellite.

2. The method according to claim 1, characterized in that The determining of the second satellite comprises: The second satellite is determined according to one or more of the following: ephemeris information, information of the terminal, status information of the first satellite and / or the second satellite, and a migration strategy of the terminal context.

3. The method according to claim 1 or 2, characterized in that The method further comprises: Determine at least one of the following based on the ephemeris information and / or the terminal information: The waiting time for the first satellite to serve the terminal, The waiting time for the second satellite to serve the terminal, The difference between the waiting time for the first satellite and the waiting time for the second satellite to serve the terminal.

4. The method according to any one of claims 1 to 3, characterized in that The migrating the context information corresponding to the terminal from the first satellite to the second satellite includes: According to a terminal context migration strategy, if the waiting time for the first satellite to serve the terminal is greater than or equal to a first threshold, the context information corresponding to the terminal is migrated from the first satellite to the second satellite; wherein the terminal context migration strategy includes the first threshold; and / or, According to the terminal context migration strategy, if the waiting time for the second satellite to serve the terminal is shorter than the waiting time for the first satellite to serve the terminal, the context information corresponding to the terminal is migrated from the first satellite to the second satellite.

5. The method according to claim 4, characterized in that The waiting time for the second satellite to serve the terminal is shorter than the waiting time for the first satellite to serve the terminal, including: A difference between a waiting time for the second satellite to serve the terminal and a waiting time for the first satellite to serve the terminal is greater than or equal to a second threshold; wherein the terminal context migration strategy includes the second threshold.

6. The method according to claim 4, characterized in that The first threshold includes at least one of the following: The delay that the terminal can tolerate or the configured maximum delay, The tolerable delay or the configured maximum delay of the first service of the terminal, The maximum delay that can be tolerated or triggered by any terminal and / or service.

7. The method according to claim 5, characterized in that The second threshold is a minimum delay difference between the terminal and different satellites for establishing connections that triggers the migration of the terminal context information, and the second threshold includes at least one of the following: The delay difference that the terminal can tolerate or the configured maximum delay difference, The delay difference that the first service of the terminal can tolerate or the configured maximum delay difference, The maximum delay difference that can be tolerated by any terminal and / or service to trigger context migration.

8. The method according to any one of claims 1 to 7, characterized in that The method further comprises: pre-configuring a migration strategy for the terminal context; or, A migration strategy of the terminal context is obtained from a first device, wherein the first device is a home subscriber server, a unified data management function, a policy and charging rule function, a policy control function, or an application function.

9. The method according to any one of claims 1 to 8, characterized in that The information of the terminal includes at least one of the following information: an identifier of the terminal, location information of the terminal, and information of services supported or accessed by the terminal.

10. The method according to any one of claims 1 to 9, characterized in that The context information corresponding to the terminal includes at least one item of the following information: a terminal identifier assigned to the terminal by the first satellite, a terminal identifier assigned to the terminal by a control plane function of a core network, session-related information corresponding to the terminal, subscription information of the terminal, capability information of the terminal, a tracking area identifier corresponding to the terminal, and an identifier of the first satellite.

11. The method according to any one of claims 1 to 10, characterized in that The method is applied to network equipment deployed on the ground.

12. The method according to claim 11, characterized in that Before migrating the context information corresponding to the terminal from the first satellite to the second satellite, the method further includes: A first message is received, where the first message includes downlink data corresponding to the terminal, or the first message is used to indicate that the downlink data corresponding to the terminal arrives through a user plane function.

13. The method according to claim 11 or 12, characterized in that Migrating the context information corresponding to the terminal from the first satellite to the second satellite includes: Sending a second message to the first satellite, used to instruct the first satellite to send context information corresponding to the terminal; receiving a response message from the first satellite, where the response message includes context information corresponding to the terminal; Sending context information corresponding to the terminal to the second satellite.

14. The method according to claim 11 or 12, characterized in that Migrating the context information corresponding to the terminal from the first satellite to the second satellite includes: A third message is sent to the first satellite, where the third message includes an identifier of the second satellite and is used to instruct the first satellite to send context information corresponding to the terminal to the second satellite.

15. The method according to claim 11 or 12, characterized in that Migrating the context information corresponding to the terminal from the first satellite to the second satellite includes: A fourth message is sent to the second satellite, where the fourth message includes an identifier of the first satellite and is used to instruct the second satellite to obtain context information corresponding to the terminal from the first satellite.

16. The method according to claim 14, characterized in that If no inter-satellite link exists between the first satellite and the second satellite, the method further includes: receiving a response message to the third message, the response message including context information of the terminal; Sending context information corresponding to the terminal to the second satellite.

17. The method according to claim 15, characterized in that If no inter-satellite link exists between the first satellite and the second satellite, the method further includes: receiving a response message to the fourth message, where the response message indicates that there is no intersatellite link or indicates that context information of the terminal is obtained from the first satellite; Sending a fifth message to the first satellite, used to instruct the first satellite to send context information corresponding to the terminal; receiving a response message from the first satellite, where the response message includes context information corresponding to the terminal; Sending context information corresponding to the terminal to the second satellite.

18. The method according to any one of claims 1 to 10, characterized in that The method is applied to the first satellite.

19. The method according to claim 18, characterized in that Migrating the context information corresponding to the terminal from the first satellite to the second satellite includes: Sending context information corresponding to the terminal to the second satellite.

20. The method according to claim 18, wherein Migrating the context information corresponding to the terminal from the first satellite to the second satellite includes: A sixth message is sent to a second device, the sixth message including context information corresponding to the terminal, the sixth message being used to indicate migration of the context information corresponding to the terminal, and the second device being a network device deployed on the ground.

21. The method according to claim 20, characterized in that The sixth message includes an identifier of the second satellite, and the sixth message is used to instruct to send the context information corresponding to the terminal to the second satellite.

22. The method according to any one of claims 18 to 21, characterized in that Before migrating the context information corresponding to the terminal from the first satellite to the second satellite, the method further includes: A seventh message is sent, where the seventh message includes uplink data or uplink signaling corresponding to the terminal.

23. The method according to any one of claims 1 to 22, characterized in that The first satellite operates in a regeneration and forwarding mode, and / or the first satellite operates in a feed connection discontinuous mode.

24. A communication device, characterized in that: The communication device is used to implement the method according to any one of claims 1 to 23.

25. A communication device, characterized in that: include: A processor is coupled to a memory, wherein the memory is used to store a program or an instruction, and when the program or the instruction is executed by the processor, the method according to any one of claims 1 to 23 is performed.

26. A computer-readable storage medium having a computer program or instruction stored thereon, characterized in that: When the computer program or instructions are executed, the method according to any one of claims 1 to 23 is performed.

27. A computer program product, comprising computer program code, characterized in that: When the computer program code is run on a computer, the method according to any one of claims 1 to 23 is executed.

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