Data transmission system and communication apparatus

Abstract

Disclosed in the present application are a data transmission system and a communication apparatus. The system comprises a terminal device, a first satellite, and a second satellite; the terminal device sends a first request to the first satellite, the first request being used for requesting to resume a radio resource control connection, and the first satellite being located in a service link area; the first satellite sends first context information of the terminal device to the second satellite; the second satellite sends a second request to a core network, the second request being used for instructing the core network to modify and activate a bearer, and the second satellite being located in a feeder link area; and after the second satellite enters the service link area from the feeder link area, the second satellite sends scheduling signaling to the terminal device, the time when the second satellite enters the service link area from the feeder link area being earlier than the time when the first satellite re-enters the service link area. The system helps to reduce latency and reduce power consumption of terminal devices.

Description

Data transmission system and communication device

[0001] This application claims priority to Chinese Patent Application No. 202410934312.3, filed on July 12, 2024, entitled “Data Transmission System and Communication Apparatus”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of communications, and more particularly to a data transmission system and a communication device. Background Technology

[0003] Non-terrestrial network store-and-forward is a communication method that uses satellites or other spacecraft as relay nodes to achieve data storage and forwarding. In non-terrestrial network store-and-forward mode, the service link and feeder link cannot coexist. When the satellite is in the service link area, the service link exists, and the satellite interacts with the terminal equipment; when the satellite is in the feeder link area, the feeder link exists, and the satellite interacts with the core network.

[0004] When a terminal device needs to send uplink data or receive downlink data, it must first restore the user plane link. This restoration involves interaction between the satellite and the terminal device, as well as between the satellite and the core network. Specifically, the user plane link restoration process can be as follows: First, the terminal device sends a Radio Resource Control (RRC) Connection Resume request to the satellite (the satellite where the terminal device is hosted, and which is located in the serving link area). The terminal device and the satellite complete the RRCConnectionResume process, which is the interaction between the satellite and the terminal device in the first moment. Second, the satellite moves from the serving link area to the feeder link area. The satellite and the core network complete the UE Context Resume process and modify and activate the radio bearer, which is the interaction between the satellite and the core network in the second moment. Third, the satellite returns to the serving link area and notifies the terminal device that the serving plane link restoration is complete. Through these three interactions, the terminal device completes the entire user plane link restoration process. Afterward, the terminal device can receive forwarded data from the satellite or send uplink data to the satellite for storage.

[0005] In other words, the above-mentioned user plane link recovery process can only be completed when the satellite returns to the service link area, making the entire user plane link recovery process time-consuming and with high latency.

[0006] Summary of the Invention

[0007] This application provides a data transmission system and communication device that helps reduce latency and power consumption of terminal devices.

[0008] In a first aspect, some embodiments of this application provide a data transmission system including a terminal device, a first satellite, and a second satellite. The terminal device sends a first request to the first satellite, requesting the restoration of a radio resource control connection. The first satellite is located in a serving link area. The first satellite sends first context information of the terminal device to the second satellite, the first context information including information from the first request. The second satellite sends a second request to the core network, the second request instructing the core network to modify and activate a bearer. The second satellite is located in a feeder link area, the second request including the first context information. After the second satellite enters the serving link area from the feeder link area, the second satellite sends a scheduling signaling to the terminal device, the scheduling signaling instructing the terminal device to receive downlink data / send uplink data. The time when the second satellite enters the serving link area from the feeder link area is earlier than the time when the first satellite re-enters the serving link area.

[0009] In this way, since the second satellite enters the service link area earlier than the first satellite re-enters the service link area, the user plane link is restored through the collaboration of the first and second satellites. The terminal equipment does not need to wait for the first satellite to return to the service link area for a long time, thus the user plane link restoration process can be completed faster and the latency is reduced.

[0010] In one possible implementation, the first satellite determines the second satellite from among the multiple satellites in the network based on multiple ephemeris information corresponding to multiple satellites in the network. The second satellite is the satellite that arrives at the service link area first in the network.

[0011] In this way, satellites in the same network can obtain each other's ephemeris information, and the first satellite can accurately determine the satellite that arrives at the service link area first in the network through the ephemeris information.

[0012] In one possible implementation, the ephemeris information includes position information and velocity information; the first satellite determines the second satellite from the multiple satellites in the network based on the multiple ephemeris information corresponding to the multiple satellites in the network, including: the first satellite determines the satellite that arrives at the service link area first in the network based on the multiple position information and multiple velocity information corresponding to the multiple satellites in the network; and the satellite that arrives at the service link area first is determined as the second satellite.

[0013] Using the above method, the satellite's position and velocity information can be used to accurately determine the satellite that arrives at the service link area first from the network.

[0014] In one possible implementation, the second satellite sends its ephemeris information to the first satellite via an inter-satellite link.

[0015] In this way, satellites in the same network can communicate directly through inter-satellite links without having to establish new links, thus saving transmission time and signaling consumption.

[0016] In one possible implementation, the first satellite sends the first context information of the terminal device to the second satellite, including: the first satellite sending the first context information of the terminal device to the second satellite via an inter-satellite link.

[0017] In this way, satellites in the same network can communicate directly through inter-satellite links. When the first satellite and the second satellite are in the same network, there is no need to re-establish a new link between them, saving transmission time and signaling consumption.

[0018] In one possible implementation, the first request includes one or more of the following information: recovery identifier, recovery reason, and recovery parameters.

[0019] Secondly, some embodiments of this application provide another data transmission system, which includes a terminal device, a first satellite, and a second satellite. The system comprises the following steps: Step 1: The terminal device sends a first request to the first satellite, requesting the restoration of the radio resource control connection. The first satellite is located in the service link area. Step 2: After the first satellite enters the feed link area from the service link area, it sends a second request to the core network, instructing the core network to modify and activate the bearer. Step 3: The first satellite sends second context information of the terminal device to the second satellite, including information from the first request and the interaction results between the first satellite and the core network. Step 4: The second satellite sends a scheduling signaling message to the terminal device, instructing the terminal device to receive downlink data / send uplink data. The second satellite is located in the service link area. When the second satellite enters the service link area, the first satellite has not yet re-entered the service link area.

[0020] In one possible implementation, the first satellite determines the second satellite from among the multiple satellites in the network based on multiple ephemeris information corresponding to multiple satellites in the network. The second satellite is either the first satellite in the network to arrive at the service link area, or the second satellite is the satellite currently in the service link area of ​​the network.

[0021] In one possible implementation, the ephemeris information includes position information and velocity information; the first satellite determines the second satellite from the multiple satellites in the network based on multiple ephemeris information corresponding to multiple satellites in the network, including: the first satellite determines the satellite that arrives at the service link area first in the network, or determines the satellite currently in the service link area in the network, based on multiple position information and multiple velocity information corresponding to multiple satellites in the network; the satellite that arrives at the service link area first, or the satellite currently in the service link area in the network, is determined as the second satellite.

[0022] In one possible implementation, the second satellite sends its ephemeris information to the first satellite via an inter-satellite link.

[0023] In one possible implementation, the first satellite sends second context information of the terminal device to the second satellite, including: the first satellite sending the second context information of the terminal device to the second satellite via an inter-satellite link.

[0024] In one possible implementation, the first request includes one or more of the following information: recovery identifier, recovery reason, and recovery parameters.

[0025] Thirdly, some embodiments of this application provide a data transmission method. This method is applied to a terminal device and may include: the terminal device sending a first request to a first satellite, the first request being used to request the restoration of a radio resource control connection; the terminal device receiving a scheduling signaling sent by a second satellite, the scheduling signaling being used to instruct the terminal device to receive downlink data / send uplink data; wherein the second satellite enters the service link area from the feed link area earlier than the first satellite re-enters the service link area.

[0026] In one possible implementation, the first request includes one or more of the following information: recovery identifier, recovery reason, and recovery parameters.

[0027] Fourthly, this application provides a data transmission method applied to a first satellite. The method includes: receiving a first request sent by a terminal device, the first request being used to request the restoration of a radio resource control connection, the first satellite being located in a service link area; and sending first context information of the terminal device to a second satellite, the first context information including at least the information in the first request; wherein the second satellite enters the service link area from the feed link area earlier than the first satellite re-enters the service link area.

[0028] In one possible implementation, the first satellite determines the second satellite from among the multiple satellites in the network based on multiple ephemeris information corresponding to multiple satellites in the network. The second satellite is the satellite that arrives at the service link area first in the network.

[0029] In one possible implementation, the ephemeris information includes position information and velocity information; the first satellite determines the second satellite from the multiple satellites in the network based on the multiple ephemeris information corresponding to the multiple satellites in the network, including: the first satellite determines the satellite that arrives at the service link area first in the network based on the multiple position information and multiple velocity information corresponding to the multiple satellites in the network; and the satellite that arrives at the service link area first is determined as the second satellite.

[0030] In one possible implementation, the first satellite sends the first context information of the terminal device to the second satellite, including: the first satellite sending the first context information of the terminal device to the second satellite via an inter-satellite link.

[0031] In one possible implementation, the first request includes one or more of the following information: recovery identifier, recovery reason, and recovery parameters.

[0032] Fifthly, this application provides a data transmission method applied to a second satellite. The method includes: receiving first context information of a terminal device transmitted by a first satellite, the first context information including at least information from a first request, the first request being sent by the terminal device to the first satellite, the first request being used to request the restoration of a radio resource control connection; sending a second request to a core network, the second request being used to instruct the core network to modify and activate a bearer, the second satellite being located in a feeder link area, the second request including the first context information; after the second satellite enters a service link area from the feeder link area, sending a scheduling signaling to the terminal device, the scheduling signaling being used to instruct the terminal device to receive downlink data / send uplink data; wherein the time when the second satellite enters the service link area from the feeder link area is earlier than the time when the first satellite re-enters the service link area.

[0033] In one possible implementation, the second satellite sends its ephemeris information to the first satellite via an inter-satellite link.

[0034] In one possible implementation, the first request includes one or more of the following information: recovery identifier, recovery reason, and recovery parameters.

[0035] Sixthly, some embodiments of this application provide a data transmission method. This method is applied to a terminal device and may include: the terminal device sending a first request to a first satellite, the first request being used to request the restoration of a radio resource control connection; the terminal device receiving scheduling signaling sent by a second satellite, the scheduling signaling being used to instruct the terminal device to receive downlink data / send uplink data; wherein the second satellite enters the service link area from the feed link area earlier than the first satellite re-enters the service link area.

[0036] In one possible implementation, the first request includes one or more of the following information: recovery identifier, recovery reason, and recovery parameters.

[0037] In a seventh aspect, this application provides a data transmission method applied to a first satellite. The method includes: after the first satellite enters a feed link area from a service link area, the first satellite sends a second request to the core network, the second request being used to instruct the core network to modify and activate the bearer; the first satellite sends second context information of a terminal device to a second satellite, the second context information including information from the first request and the interaction result between the first satellite and the core network; wherein, when the second satellite enters the service link area, the first satellite has not yet re-entered the service link area.

[0038] In one possible implementation, the first satellite determines the second satellite from among the multiple satellites in the network based on multiple ephemeris information corresponding to multiple satellites in the network. The second satellite is either the first satellite in the network to arrive at the service link area, or the second satellite is the satellite currently in the service link area of ​​the network.

[0039] In one possible implementation, the ephemeris information includes position information and velocity information; the first satellite determines the second satellite from the multiple satellites in the network based on multiple ephemeris information corresponding to multiple satellites in the network, including: the first satellite determines the satellite that arrives at the service link area first in the network based on multiple position information and multiple velocity information corresponding to multiple satellites in the network; the satellite that arrives at the service link area first, or the second satellite is the satellite currently in the service link area in the network, is determined as the second satellite.

[0040] In one possible implementation, the first satellite sends second context information of the terminal device to the second satellite, including: the first satellite sending the second context information of the terminal device to the second satellite via an inter-satellite link.

[0041] In one possible implementation, the first request includes one or more of the following information: recovery identifier, recovery reason, and recovery parameters.

[0042] Eighthly, this application provides a data transmission method applied to a second satellite. The method includes: receiving second context information of a terminal device transmitted by a first satellite, the second context information including at least information in a first request and the interaction result between the first satellite and the core network; and the second satellite sending scheduling signaling to the terminal device, the scheduling signaling being used to instruct the terminal device to receive downlink data / send uplink data.

[0043] In one possible implementation, the second satellite sends its ephemeris information to the first satellite via an inter-satellite link.

[0044] In one possible implementation, the first request includes one or more of the following information: recovery identifier, recovery reason, and recovery parameters.

[0045] Ninthly, embodiments of this application provide a communication apparatus, including a function / unit for performing the communication method in the third aspect and any possible implementation thereof, or including a function / unit for performing the communication method in the fourth aspect and any possible implementation thereof, or including a function / unit for performing the data transmission method in the fifth aspect and any possible implementation thereof.

[0046] In a tenth aspect, embodiments of this application provide a communication device, including a processor, a memory, and a communication interface; the communication interface is used to realize communication between the processor and the memory, the memory stores one or more computer programs, the one or more computer programs include instructions, and when the instructions are executed by the processor, the communication device performs the data transmission method in the third aspect and any possible implementation thereof, or performs the data transmission method in the fourth aspect and any possible implementation thereof, or performs the fifth aspect, or performs the sixth aspect, or performs the seventh aspect, or performs the data transmission method in the eighth aspect and any possible implementation thereof.

[0047] Eleventhly, this application provides a chip applied to a terminal device / first satellite / second satellite. The chip system includes a processor and an interface. The interface is used to receive or output signals and transmit them to the processor. The processor is used to implement the data transmission method in the third aspect and any of its possible implementations, or to implement the data transmission method in the fourth aspect and any of its possible implementations, or to implement the fifth aspect, or to execute the sixth aspect, or to execute the seventh aspect, or to execute the data transmission method in the eighth aspect and any of its possible implementations.

[0048] In a twelfth aspect, this application provides a computer-readable storage medium storing a computer program that, when invoked by a computer, causes the computer to execute the data transmission method in the third aspect and any possible implementation thereof, or to execute the data transmission method in the fourth aspect and any possible implementation thereof, or to execute the fifth aspect, or to execute the sixth aspect, or to execute the seventh aspect, or to execute the data transmission method in the eighth aspect and any possible implementation thereof.

[0049] In a thirteenth aspect, this application provides a computer program product that, when run on a computer, causes the computer to execute the data transmission method in the third aspect and any possible implementation thereof, or execute the data transmission method in the fourth aspect and any possible implementation thereof, or execute the fifth aspect, or execute the sixth aspect, or execute the seventh aspect, or execute the data transmission method in the eighth aspect and any possible implementation thereof.

[0050] Understandably, the beneficial effects achievable by the communication devices, chips, computer-readable storage media, computer program products, and communication systems provided above can be referenced to the beneficial effects in the first, second, third, fourth, fifth, sixth, seventh, and eighth aspects and any possible implementation thereof, which will not be repeated here. Attached Figure Description

[0051] Figure 1A is a schematic diagram of a user plane link recovery process provided in an embodiment of this application;

[0052] Figure 1B is a schematic diagram of a user plane link recovery system provided in an embodiment of this application;

[0053] Figure 1C is a schematic diagram of another user plane link recovery system provided in an embodiment of this application;

[0054] Figure 2 is a schematic diagram of a communication system provided in an embodiment of this application;

[0055] Figure 3 is a schematic diagram of a data transmission process provided in an embodiment of this application;

[0056] Figure 4A is a schematic diagram of another data transmission process provided in an embodiment of this application;

[0057] Figure 4B is a schematic diagram of another data transmission system provided in an embodiment of this application;

[0058] Figure 5A is a schematic diagram of another data transmission system provided in an embodiment of this application;

[0059] Figure 5B is a schematic diagram of another data transmission process provided in an embodiment of this application;

[0060] Figure 5C is a schematic diagram of another data transmission system provided in an embodiment of this application;

[0061] Figure 6 is a schematic diagram of the structure of a communication device provided in an embodiment of this application;

[0062] Figure 7 is a schematic diagram of another communication device provided in an embodiment of this application;

[0063] Figure 8 is a schematic diagram of the structure of a chip provided in an embodiment of this application. Detailed Implementation

[0064] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. In the description of the embodiments of this application, unless otherwise stated, " / " means "or," for example, A / B can mean A or B; "and / or" in the text is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Furthermore, in the description of the embodiments of this application, "multiple" refers to two or more than two.

[0065] It should be understood that the terms "first," "second," etc., in the specification, claims, and drawings of this application are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or apparatuses.

[0066] In this application, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this application can be combined with other embodiments.

[0067] To facilitate understanding of the solutions provided in the embodiments of this application, the relevant concepts involved in the embodiments of this application are introduced below:

[0068] I. Wireless Bearer

[0069] The Radio Bearer (RB) is the channel connecting the base station (eNodeB, eNB) and the UE on the radio interface. All data transmitted on the radio interface must pass through the RB. There are two types of radio bearers: Signaling Radio Bearer (SRB) and Data Radio Bearer (DRB). Specifically: SRB represents the radio bearer for transmitting Radio Resource Control (RRC) and Non-Access Stratum (NAS) messages. DRB represents the data radio bearer for packet processing in the radio interface (Uu). The DRB is responsible for providing the same packet forwarding processing for (user) data packets.

[0070] II. Contextual Information

[0071] Context information may include established session states, security parameters, radio resource configurations, etc. When the UE reconnects, this context information is used to ensure data continuity, speed up recovery, and improve communication quality.

[0072] This context information may include the access stratum (AS) context information saved by the user equipment (UE) before entering the idle or inactive state, thereby ensuring that data continuity is maintained when the connection is restored after the terminal is connected, and that a large amount of data is not lost or retransmitted due to interruption.

[0073] This context information can include radio resource configuration and other details, enabling RRC connections to be restored quickly. It eliminates the need for a complete connection establishment process, reducing the time and signaling overhead required to restore the connection.

[0074] This contextual information may include measurement configuration and mobility management information. This information helps the network better manage UE mobility and optimize the allocation and use of radio resources.

[0075] This contextual information can include security parameters, such as encryption and integrity protection parameters, to ensure the security of data transmission. During connection restoration, these security parameters can be immediately applied to new data transmissions to prevent data interception or tampering during transmission.

[0076] III. Inter-satellite links

[0077] Inter-satellite links (ISLs) are direct communication connections established between different satellites to enable data transmission and communication between satellite networks. In modern satellite communication systems, ISL technology is widely used to improve system flexibility and reliability while reducing reliance on ground infrastructure. This technology allows satellites to exchange information directly in space without the need for ground stations, significantly reducing communication latency and improving data transmission efficiency and reliability.

[0078] IV. User Plane Link Recovery

[0079] In certain scenarios (such as the NB-IoT UP CIOT scheme for user plane transmission in narrowband IoT technology), when the terminal device is in an inactive state, it can request user plane link restoration via RRC Connection Resume Request signaling. This user plane link restoration can be divided into two parts: bearer restoration between the UE and the eNB, and interaction between the eNB and the core network to activate the bearer. Therefore, by restoring the link between the terminal device and the eNB, and the link between the eNB and the core network, the connection between the terminal device and the core network via the eNB is restored, thus completing the user plane link restoration.

[0080] The following describes the user plane link recovery process using Figure 1A. The UE in Figure 1A can also be called a terminal device. The eNB in ​​Figure 1A can be a satellite, a base station, or an access network device. The Mobility Management Entity (MME) is a core network element in the core network, responsible for mobility management, NAS signaling, and security functions. The Serving Gateway (S-GW) is a key component in the core network, responsible for handling user plane data forwarding, charging, and mobility management functions.

[0081] First, when the UE is in an inactive state, 101. The UE sends a Random Access Preamble to the eNB, and the eNB receives the Random Access Preamble sent by the UE. This Random Access Preamble is used to request initial network access, for example, when the UE first powers on or enters from outside the eNB's coverage area; or it is used for network connection reconstruction, for example, after a connection loss, the UE can use the Random Access Preamble to re-establish the network connection. After receiving the Random Access Preamble, the eNB decodes it, performs scheduling measurements based on the received Random Access Preamble, and responds to the Random Access Preamble by allocating resources to the UE.

[0082] 102. The eNB sends a Random Access Response to the UE. Correspondingly, the UE receives the Random Access Response sent by the eNB.

[0083] Optionally, the Random Access Response message may include resource information allocated to the UE and related scheduling instructions.

[0084] 103. The UE sends an RRCConnectionResumeRequest to the eNB. Correspondingly, the eNB receives the RRCConnectionResumeRequest sent by the UE.

[0085] Optionally, the RRCConnectionResumeRequest is a signaling message used to request the restoration of an RRC connection. This message is primarily used to quickly restore a connection based on an existing RRC connection, reducing the time and resource consumption required to re-establish the connection.

[0086] 104. The eNB sends an RRC connection restore (RRCConnectionResume) to the UE. Correspondingly, the UE receives the RRCConnectionResume sent by the eNB.

[0087] The RRCConnectionResume message is used to restore a suspended RRC connection, enabling the UE to transition from an inactive state to a connected state.

[0088] Optionally, the RRCConnectionResume includes several important parameters and configuration information used to restore the RRC connection and re-establish the data transmission channel. Specifically, the RRCConnectionResume may include: AS context information, which is relevant information saved before the UE enters the idle state and is used for quick connection restoration; it may also include: SRB and DRB configuration information, which is used to re-establish the control and user data transmission channels; and other information, which is not limited herein.

[0089] Optionally, in step 104, the bearer between the UE and the eNB is restored, and the UE enters the connected state. Optionally, AS security also needs to be rebuilt.

[0090] 105. The UE sends an RRC connection recovery complete message (RRCConnectionResumeComplete) to the eNB, and the eNB receives the RRCConnectionResumeComplete message sent by the UE.

[0091] Optionally, the RRCConnectionResumeComplete is used to inform the eNB that the bearer restoration between the UE and the eNB is complete.

[0092] After the UE and eNB complete steps 101-105 above, the bearer between the UE and eNB is restored. However, the interaction between the eNB and the core network has not yet taken place, so the user plane link has not been restored. At this time, the eNB has not yet moved to the feeder link area, and the UE needs to wait for the eNB to interact with the core network (MME and S-GW).

[0093] After the UE and eNB complete steps 101-105 above, it is necessary to wait for the eNB and core network to complete the UE Context Resume procedure. The specific UE Context Resume procedure can be as follows:

[0094] 106. The eNB sends a UE Context Resume Request to the MME in the core network. Correspondingly, the MME in the core network receives the UE Context Resume Request sent by the eNB.

[0095] 107. Modify and activate the bearer in the MME and S-GW of the core network.

[0096] 108. The MME in the core network sends a UE Context Resume Response to the eNB. Correspondingly, the eNB receives the UE Context Resume Response sent by the MME in the core network.

[0097] 109. The eNB sends a scheduling signaling message to the UE. Correspondingly, the UE receives the scheduling signaling message sent by the eNB. This scheduling signaling message instructs the terminal device to send uplink data / receive downlink data. After step 109 is completed, the user plane link is restored, and the terminal device can transmit uplink / downlink data.

[0098] V. Store-and-forward mode

[0099] Store & Forward (S&F) mode. Store & forward mode refers to a mode where the base station receives and stores all data during transmission before forwarding it. For example, when a UE sends uplink data, the satellite receives all the uplink data sent by the UE and then forwards it to the core network; or when a UE receives downlink data, the satellite receives all the downlink data sent by the core network and then forwards it to the UE.

[0100] VI. Non-terrestrial networks

[0101] Non-terrestrial Network (NTN) is a technology for direct communication between terminal devices and satellites. Current NTN supports S&F mode. In NTN, satellites move along orbits, so the service link and feeder link cannot exist simultaneously. The service link between the satellite and the UE can only exist when the satellite is in the service link area; the feeder link between the satellite and the core network can only exist when the satellite is in the feeder link area. That is, in NTN store-and-forward mode, when the UE sends uplink data, it needs the satellite to be in the service link area. The UE sends the uplink data to the satellite through the service link. After the satellite receives and stores the uplink data, it moves around its orbit to the feeder link area and then forwards the uplink data to the core network through the feeder link. Similarly, when the UE receives downlink data, it needs the satellite to be in the feeder link area. The core network sends the downlink data to the satellite through the feeder link. After the satellite receives and stores the downlink data, it moves around its orbit to the service link area and then forwards the downlink data to the UE through the service link.

[0102] As shown in Figure 1B, at the first moment, the satellite is in the serving link area, at which time the UE can interact with the satellite to restore the link between the terminal device and the satellite. At the second moment, the satellite moves from the serving link area to the feeder link area, at which time the satellite can interact with the core network to restore the link between the satellite and the core network. At the third moment, the satellite returns from the feeder link area to the serving link area, at which time the satellite informs the terminal device that the user plane link restoration is complete, and the terminal device can send uplink data / receive downlink data. That is, after the third moment, the link between the terminal device and the core network through the eNB is restored, thus completing the restoration of the entire user plane link.

[0103] Therefore, in NTN store-and-forward mode, the user plane link recovery can be seen in Figure 1C. The process marked 110 in Figure 1C corresponds to the first moment in Figure 1B. In process 110, the satellite is in the serving link area, and interaction occurs between the satellite and the UE. The process marked 111 in Figure 1C corresponds to the second moment in Figure 1B. In process 111, the satellite is in the feeder link area, and interaction occurs between the satellite and the core network. The process marked 112 in Figure 1C corresponds to the third moment in Figure 1B. In process 112, the satellite returns to the serving link area, and interaction occurs between the satellite and the UE.

[0104] In summary, under NTN store-and-forward mode, the satellite needs to move from the serving link area to the feeder link area and then back to the serving link area to complete the entire user plane link recovery. During the entire user plane link recovery process, after procedure 110 in Figure 1C is completed, the UE still needs to continuously monitor the physical downlink control channel. Therefore, not only is the latency high, but the UE's power consumption is also high.

[0105] To address the aforementioned issues of high latency and high UE power consumption, this application provides a data transmission system that uses a first satellite and a second satellite to collaboratively restore the user plane link. The terminal device does not need to wait for the first satellite to return to the service link area to complete the user plane link restoration process, thereby reducing latency and power consumption of the terminal device.

[0106] The technical solutions of this application embodiment can be applied to various communication systems, such as satellite communication systems and traditional mobile communication systems. Satellite communication systems have been introduced by the 3rd Generation Partnership Project (3GPP) under the name of non-terrestrial network (NTN), and can be integrated with traditional mobile communication systems (i.e., terrestrial network (TN)). Examples of mobile communication systems include: wireless local area network (WLAN) systems, wireless fidelity (WiFi) systems, long term evolution (LTE) systems, LTE frequency division duplex (FDD) systems, LTE time division duplex (TDD) systems, 4th generation (4G) systems, 5th generation (5G) systems, or new radio (NR) systems, and other future communication systems, such as 6th generation (6G) systems. Furthermore, it supports communication systems that integrate multiple wireless technologies. For example, it can also be applied to systems that integrate NTN terrestrial mobile communication networks, such as those for drones, satellite communication systems, and high altitude platform station (HAPS) communication. It is understood that the system architecture described in the embodiments of this application is for the purpose of more clearly illustrating the technical solutions of the embodiments of this application and does not constitute a limitation on the technical solutions provided in the embodiments of this application.

[0107] Please refer to Figure 2 below, which shows a schematic diagram of a communication system. As shown in Figure 2, the communication system includes a terminal device 201, a first satellite 202, a second satellite 203, and a core network 204. Figure 2 uses one terminal device 201, one first satellite 202, and one second satellite 203 as an example. The communication system may also include more terminal devices 201, first satellites 202, and second satellites 203. This application embodiment does not limit the number of such devices.

[0108] Terminal device 201 can also be referred to as a terminal, user equipment (UE), mobile station, mobile terminal, electronic device, etc. Terminal device 201 can be widely used in various scenarios, such as device-to-device (D2D), vehicle-to-everything (V2X) communication, machine-type communication (MTC), Internet of Things (IoT), virtual reality, augmented reality, industrial control, autonomous driving, telemedicine, smart grids, smart furniture, smart offices, smart wearables, smart transportation, smart cities, etc. Terminal device 201 can be a mobile phone, tablet computer, computer with wireless transceiver capabilities, wearable device, vehicle, drone, helicopter, airplane, ship, robot, robotic arm, smart home device, etc.

[0109] The first satellite 202 can also be referred to as a satellite base station, an airborne base station, or an access network device. It can also be called a radio access network (RAN) node, RAN entity, or access node, forming part of the communication system to help terminal device 201 achieve wireless access. In one possible scenario, the first satellite 202 can be a base station, an evolved NodeB (eNodeB), an access point (AP), a transmission reception point (TRP), a next-generation NodeB (gNB), a next-generation base station in a 6th-generation (6G) mobile communication system, a base station in a future mobile communication system, or an access node in a WiFi system.

[0110] The second satellite 203 can be described in the above description of the first satellite 202, and will not be repeated here.

[0111] The Core Network (CN) 204 not only connects the radio access network to external networks, such as the Internet or other mobile networks, but also is responsible for a variety of key network functions to ensure the reliability and efficiency of communication services.

[0112] The core network's main functions include user authentication, session management, policy and charging control, data routing and forwarding, etc. These functions are implemented through different network elements, such as MME (Mobility Management Entity), SGW (Serving Gateway), PGW (PDN Gateway), and HSS (Home Subscriber Server). For example, when a user equipment initiates a communication request, the core network uses the MME for user authentication and network security management, and then uses the SGW and PGW to handle packet forwarding and policy enforcement. As shown in Figure 2, the core network 204 may also include a satellite observation gateway (GW). The satellite observation gateway is used to connect the satellite and the core network.

[0113] Based on the above, a data transmission system provided by an embodiment of this application will be further described in detail below. As shown in Figure 3, the data transmission system includes the following steps: Step 1-Step 4. Wherein:

[0114] Step 1: The terminal device sends a first request to the first satellite, which requests the restoration of the radio resource control connection. The first satellite is located in the service link area. Correspondingly, the first satellite receives the first request sent by the terminal device.

[0115] Optionally, in non-terrestrial network store-and-forward mode, the terminal device sends a first request to the first satellite, which is used to request the restoration of the radio resource control connection, and the first satellite is located in the service link area.

[0116] Optionally, the terminal device sends a first request to the first satellite, including: the terminal device sending the first request to the first satellite through a first service link, the first service link being used to transmit various signaling messages between the terminal device and the first satellite. It should be noted that this first service link is different from the link between the terminal device and the satellite mentioned above; this first service link is used to transmit signaling messages, while the link between the terminal device and the satellite that needs to be restored is used to transmit user data, etc. This can be understood as restoring the bearer between the terminal device and the satellite through the first service link, thereby restoring the link between the terminal device and the satellite during user plane link restoration.

[0117] Optionally, the first satellite is the satellite on which the terminal device is currently camped. When the first satellite is camped, a first service link exists between the first satellite and the terminal device. The terminal device can only camp when the first satellite is within the service link area.

[0118] Optionally, the first satellite is in an idle or inactive state before the terminal device sends the first request.

[0119] Optionally, the terminal device and the first satellite can interact via the first service link. This first service link can only exist when the first satellite is within the service link area. If it is in a non-terrestrial network store-and-forward mode, the first service link will not exist when the first satellite is within the power supply link area.

[0120] Optionally, multiple service link regions may exist, with the service link region where the first service link is located being the service link region corresponding to the terminal device. For example, terminal device A corresponds to service link region A, and terminal device B corresponds to service link region B. When the first satellite is in service link region A, a link exists between the first satellite and terminal device A. There may be overlapping areas between these service link regions. That is, when the first satellite is in a certain region, it may be in both service link region A and service link region B.

[0121] Optionally, the first request may include one or more of the following information: resume identifier (resumeID), resume reason (resumeCause), and resume parameters.

[0122] Optionally, the resumeID is used to uniquely identify the RRC connection recovery request, enabling the network to quickly restore the RRC connection state of the terminal device without re-executing the complete connection establishment process. resumeCause indicates the specific reason why the terminal device requests to restore the RRC connection; different resumeCause values ​​represent different reasons for recovery, such as network problems, device issues, etc.

[0123] Optionally, the recovery parameter can be shortResumeMAC-1, which is a short message authentication code used to verify the integrity and authenticity of the recovery request.

[0124] Optionally, the first request is an RRCConnectionResumeRequest.

[0125] Optionally, after receiving the RRCConnectionResumeRequest, the first satellite sends an RRCConnectionResume to the terminal device. This RRCConnectionResume is a response message to the RRCConnectionResumeRequest. The RRCConnectionResume includes a new encryption key.

[0126] For example, when a terminal device needs to enter a connected state from an inactive state, it generates a resumeID and sets a resumeCause based on the interruption reason (e.g., if the last RRC connection interruption was due to a network problem, the resumeCause value is set to the value corresponding to that network problem). The terminal device also calculates shortResumeMAC-1. Then, the terminal device includes the resumeID, resumeCause, and shortResumeMAC-1 in an RRCConnectionResumeRequest and sends it to the first satellite. Upon receiving the RRCConnectionResumeRequest, the first satellite verifies the correctness of shortResumeMAC-1, generates a new encryption key based on NextHopChainingCount, and sends this encryption key to the terminal device in the RRC connection recovery response. Upon receiving the recovery response, the terminal device updates the encryption key and restores the RRC connection. Here, NextHopChainingCount is a counter used for key management, ensuring that the correct encryption key is used during the recovery process.

[0127] Optionally, the first request may also include other information besides the three pieces of information mentioned above, which is not limited herein.

[0128] Optionally, before the terminal device sends the first request to the first satellite through the first service link, the method further includes: the terminal device sending a random access preamble to the first satellite through the first service link; the terminal device receiving a random access response from the first satellite through the first service link; correspondingly, the first satellite receiving the random access preamble from the terminal device through the first service link; and the first satellite sending a random access response to the terminal device through the first service link.

[0129] Optionally, after the terminal device sends the first request to the first satellite, the method further includes: the first satellite sending an RRCConnectionResume to the terminal device, wherein the RRCConnectionResume is used to manage the UE's transition to the connected state at the RRC level.

[0130] Optionally, after receiving RRCConnectionResume, the terminal device resumes the bearer between itself and the first satellite, and enters the connected state. Optionally, the terminal device will also rebuild AS security.

[0131] Optionally, the terminal device can restore the bearer between itself and the first satellite. After the terminal device enters the connected state, it can also send an RRC connection recovery completion message (RRCConnectionResumeCompelect) to the network device.

[0132] Optionally, this non-terrestrial network store-and-forward mode can be specifically defined as the NB-IoT UP CIOT solution under the non-terrestrial network store-and-forward mode.

[0133] Step 2: The first satellite sends the first context information of the terminal device to the second satellite. The first context information includes the information in the first request. Accordingly, the second satellite receives the context information sent by the first satellite. The second satellite enters the service link area from the feed link area earlier than the first satellite re-enters the service link area.

[0134] The first context information can be found in the description of context information in the above-mentioned related concepts, and will not be repeated here.

[0135] Optionally, the second satellite may enter the service link area earlier than the first satellite may re-enter the service link area.

[0136] Optionally, the second satellite satisfies the following condition: after receiving the first context information of the terminal device sent by the first satellite, it enters the power supply link area, and the time of entering the service link area is earlier than the time when the first satellite re-enters the service link area.

[0137] Optionally, the second satellite may be located in the feed link region when it receives the first context information from the terminal device, and enter the service link region earlier than the time when the first satellite re-enters the service link region; or the second satellite may not have entered the feed link region when it receives the first context information from the terminal device, but enters the feed link region within a certain period after receiving the first context information from the terminal device, and enters the service link region earlier than the time when the first satellite re-enters the service link region.

[0138] Since user plane link recovery requires interaction between the satellite and the core network, when the first and second satellites work together to complete the recovery, the first satellite needs to send the terminal device's first context information to the second satellite, and then the second satellite needs to complete the UE Context Resume procedure with the core network to modify the active bearer. Therefore, the second satellite needs to pass through the feeder link area after receiving the terminal device's first context information from the first satellite to ensure successful user plane link recovery. Furthermore, because the second satellite enters the service link area earlier than the first satellite re-enters the service link area, the latency of user plane link recovery is reduced, and for the terminal device, the time spent listening to the physical downlink control channel is shorter, resulting in lower power consumption.

[0139] Optionally, the second satellite and the first satellite can be located in the same satellite network.

[0140] Within the same satellite network, satellites can communicate with each other, share data and resources, and communicate directly via ISL (Independent Satellite Communication).

[0141] In one possible embodiment, the first satellite determines the second satellite from among the multiple satellites in the network based on multiple ephemeris information corresponding to multiple satellites in the network. The second satellite is the satellite that arrives at the service link area first in the network.

[0142] In one possible implementation, the ephemeris information includes position information and velocity information; the first satellite determines the second satellite from the multiple satellites in the network based on the multiple ephemeris information corresponding to the multiple satellites in the network, including: the first satellite determines the satellite that arrives at the service link area first in the network based on the multiple position information and multiple velocity information corresponding to the multiple satellites in the network; and the satellite that arrives at the service link area first is determined as the second satellite.

[0143] Optionally, the location information can be specifically the coordinates of the satellite on a three-dimensional coordinate axis at a particular moment, such as the satellite's coordinates in the xyz coordinate system at a certain moment. This three-dimensional coordinate axis can be established with the Earth as the origin or with another point as the origin. Optionally, all satellites use the same three-dimensional coordinate axis, meaning that the coordinates corresponding to all satellites are coordinates under the same three-dimensional coordinate axis.

[0144] Optionally, the velocity information can be the satellite's velocity in each direction, or the satellite's velocity and acceleration in each direction. For example, the satellite's velocity on the x-axis, y-axis, and z-axis.

[0145] Optionally, the first satellite pre-stores the coordinate range corresponding to the service link area. Based on multiple location information corresponding to multiple satellites in the network, multiple velocity information corresponding to multiple satellites, and the coordinate range corresponding to the service link area, the first satellite determines the satellite that arrives at the service link area first in the network.

[0146] For example, the first satellite pre-stores the coordinate range (x0-x1, y0-y1, z0-z1) corresponding to the service link area. The network to which the first satellite belongs includes the following three satellites: the first satellite, satellite A, and satellite B. The coordinates of satellite A at a certain moment are (x2, y2, z2), and the coordinates of satellite B at a certain moment are (x3, y3, z3). The velocity of satellite A is (v1, v2, v3), and the velocity of satellite B is (v4, v5, v6). At this certain moment, neither satellite A nor satellite B is in the service link area. Based on the above information about satellite A, the first satellite determines that satellite A needs time t1 to enter the service link area, that is, x2+v1*t1 is in the range x0-x1, y2+v2*t1 is in the range y0-y1, and z2+v3*t1 is in the range z0-z1. Based on the information about satellite B mentioned above, the first satellite determines that satellite B needs time t2 to enter the service link area. That is, x3+v4*t2 is in the range x0-x1, y3+v5*t2 is in the range y0-y1, and z3+v6*t2 is in the range z0-z1.

[0147] If t1 is less than t2, then satellite A is designated as the second satellite, and the first satellite sends the terminal device's first context information to satellite A. If t1 is greater than t2, then satellite B is designated as the second satellite, and the first satellite sends the terminal device's first context information to satellite B. If t1 is equal to t2, then any satellite can be selected as the second satellite; either satellite A or satellite B can be used.

[0148] Optionally, the ephemeris information includes orbital information; the orbital information is the information corresponding to the orbit of the satellite. The first satellite determines the second satellite from the multiple satellites in the network based on the ephemeris information corresponding to multiple satellites in the network, including: the first satellite determines the satellite that arrives at the service link area first in the network based on the orbital information corresponding to multiple satellites in the network; and determines the satellite that arrives at the service link area first as the second satellite.

[0149] Optionally, after receiving the first request, the first satellite determines the second satellite from among the multiple satellites in the network based on multiple ephemeris information corresponding to multiple satellites in the network.

[0150] Optionally, after receiving the RRC connection restoration notification from the terminal device, the first satellite determines the second satellite from among the multiple satellites in the network based on multiple ephemeris information corresponding to multiple satellites in the network.

[0151] Optionally, the first satellite sends the first context information of the terminal device to the second satellite via an ISL, where the ISL is the ISL between the first satellite and the second satellite.

[0152] Optionally, after identifying the second satellite, the first satellite sends the first context information of the terminal device to the second satellite via ISL.

[0153] Optionally, after receiving the first context information transmitted by the first satellite in the same satellite network, the satellite that first enters the service link area after passing through the feeder link area includes the information in the first request. This first context information may also include information other than the first request, such as AS security information.

[0154] Optionally, the second satellite may send its ephemeris information to the first satellite via an inter-satellite link.

[0155] Optionally, the ephemeris information may be sent by the second satellite to the first satellite based on a preset period, or it may be sent by the first satellite to the second satellite after being notified by the first satellite.

[0156] Optionally, the second satellite is not only the first satellite to arrive at the service link area in the network, but also the satellite that enters the power supply link area after receiving the first context information of the terminal equipment sent by the first satellite.

[0157] In one possible embodiment, the first satellite determines the second satellite from among the multiple satellites in the network based on multiple ephemeris information corresponding to multiple satellites in the network. The second satellite is the satellite in the network that received the first context information, passed through the power supply link area, and was the first to arrive at the service link area in the network.

[0158] Optionally, the second satellite is the satellite that was in the feed link area when it received the first context information in the network, and is the first satellite in the network to reach the service link area. That is, the second satellite enters the feed link area after receiving the first context information, or the second satellite is in the feed link area when it receives the first context information.

[0159] In one possible implementation, the ephemeris information includes position information and velocity information; the first satellite determines the second satellite from the multiple satellites in the network based on multiple ephemeris information corresponding to multiple satellites in the network, including: the first satellite determines the satellite in the network that received the first context information, passed through the feed link area, and was the first to arrive at the service link area in the network, based on multiple position information and multiple velocity information corresponding to multiple satellites in the network; the satellite in the network that received the first context information, passed through the feed link area, and was the first to arrive at the service link area in the network is determined as the second satellite.

[0160] Optionally, the ephemeris information includes position information and velocity information; the first satellite determines the second satellite from the multiple satellites in the network based on the multiple ephemeris information corresponding to multiple satellites in the network, including: the first satellite determines the satellite in the network that was in the feed link area when it received the first context information and that was the first to arrive at the service link area in the network, based on the multiple position information and multiple velocity information corresponding to multiple satellites in the network; the satellite in the network that was in the feed link area when it received the first context information and that was the first to arrive at the service link area in the network is determined as the second satellite.

[0161] Optionally, the ephemeris information includes orbit information; the first satellite determines the second satellite from the multiple satellites in the network based on the ephemeris information corresponding to multiple satellites in the network, including: the first satellite determines the satellite in the network that received the first context information, passed through the feed link area, and was the first to arrive at the service link area in the network, based on the multiple orbit information corresponding to multiple satellites in the network; the satellite in the network that received the first context information, passed through the feed link area, and was the first to arrive at the service link area in the network is determined as the second satellite.

[0162] Optionally, the ephemeris information includes orbit information; the first satellite determines the second satellite from the multiple satellites in the network based on the ephemeris information corresponding to multiple satellites in the network, including: the first satellite determines the satellite in the network that was in the feed link area when it received the first context information and that was the first to arrive at the service link area in the network, based on the orbit information corresponding to multiple satellites in the network; and determines the satellite in the network that was in the feed link area when it received the first context information and that was the first to arrive at the service link area in the network as the second satellite.

[0163] Optionally, the first satellite pre-stores the coordinate range corresponding to the service link area and the coordinate range corresponding to the feeder link area. Based on multiple position information, multiple velocity information, coordinate range corresponding to the service link area, and coordinate range corresponding to the feeder link area of ​​the multiple satellites in the network, the first satellite determines the satellite that arrives at the service link area first in the network.

[0164] Since the user plane link recovery process includes interaction between the terminal device and the satellite, and interaction between the satellite and the core network, and the interaction between the satellite and the core network requires first context information (for example, the first context information may include the identifier of the terminal device, and the core network needs to determine which terminal device's bearer is being restored based on the identifier of the terminal device), in this embodiment, the second satellite interacts with the core network. Therefore, after receiving the first context information sent by the first satellite, the second satellite needs to pass through / be in the feed link area in order to interact with the core network.

[0165] Optionally, for multiple satellites in the same network, a satellite that enters the feed link area first may not necessarily enter the service link area first. For example, consider satellites A (the first satellite), B, and C in the same network. Satellite C may enter the feed link area first, but because satellite B moves faster, although satellite B enters the feed link area later than satellite C, it enters the service link area earlier. Therefore, satellite A identifies satellite B as the second satellite, and the first context information of satellite A's terminal equipment is sent to satellite B.

[0166] Optionally, the first context information of the terminal device includes at least one or more of the following: resumeID, resumeCause, and recovery parameters.

[0167] Optionally, the first context information of the terminal device includes bearer information and / or AS security information between the terminal device and the first satellite. Since the bearer information between the terminal device and the first satellite has been restored in step 1, and / or the AS security information has been rebuilt, for the second satellite, based on the bearer information and / or AS security information in the first context information, the bearer information and / or AS security information between the terminal device and the second satellite can be directly restored. Therefore, after step 2, it can be considered that the bearer information between the terminal device and the second satellite has been restored, and the AS security information has been rebuilt.

[0168] Optionally, after receiving the first context information of the terminal device sent by the first satellite, the second satellite stores the first context information of the terminal device.

[0169] Step 3: The second satellite sends a second request to the core network. This second request instructs the core network to modify and activate the bearer. The second satellite is located in the feed link region, and the second request includes the first context information. Accordingly, the core network receives the second request sent by the second satellite.

[0170] Optionally, the second request is a UE Context Resume Request.

[0171] Optionally, after receiving the second request, the core network modifies and activates the bearer.

[0172] Optionally, after the core network completes the modification and activation of the bearer, the core network sends a response to the second request to the second satellite. Accordingly, the second satellite receives the response to the second request sent by the core network.

[0173] Optionally, after the core network completes the bearer modification activation, the core network sends a response to the second request to the second satellite. This response to the second request can be a UE Context Resume Response. This response informs the second satellite that the bearer modification activation has been completed.

[0174] The core network sends a UE Context Resume Response to the second satellite, at which point the link between the core network and the second satellite is restored. In other words, through steps 1-4 above, the link between the terminal device and the satellite is restored, and the link between the satellite and the core network is restored. At this point, the satellite needs to inform the terminal device that the link between the terminal device and the core network is restored.

[0175] Step 4: After the second satellite enters the service link area from the feed link area, it sends a scheduling signaling message to the terminal device. This message instructs the terminal device to receive downlink data / send uplink data. Accordingly, the terminal device receives the scheduling signaling message sent by the second satellite.

[0176] Optionally, the second satellite sends scheduling signaling to the terminal device, including: the second satellite sending scheduling signaling to the terminal device through a second service link. This second service link is used to transmit various signaling messages between the terminal device and the first satellite. Similar to the first service link, this second service link is different from the link between the terminal device and the satellite that needs to be restored. See the description of the first service link above for details.

[0177] Optionally, the second service link is a service link between the terminal device and the second satellite, and the aforementioned first service link is a service link between the terminal device and the first satellite. This second service link can exist when the second satellite is located within the service link area. The second service link area is the service link area corresponding to the terminal device.

[0178] Optionally, the scheduling instruction can also be used to notify the terminal equipment that the bearer connection between the second satellite and the core network has been restored.

[0179] Optionally, when the terminal device is in a connected state and the second satellite is in the service link area, the terminal device can send uplink data to the second satellite through the second service link; the second satellite receives the uplink data and stores it; when the second satellite is in the feeder link area, the second satellite forwards the uplink data to the core network. Alternatively, when the terminal device is in a connected state and the second satellite is in the service link area, the second satellite forwards the stored downlink data to the terminal device through the second service link.

[0180] Optionally, the terminal device sends uplink data to the second satellite via the second service link, including: after determining the timing advance (TA) compensation, the terminal device sends uplink data to the second satellite via the second service link. This TA compensation is used to adjust the uplink transmission time of the terminal device to ensure that data sent by terminal devices at different distances can arrive at the base station approximately simultaneously.

[0181] In this way, the user plane link is restored through the collaboration of the first and second satellites. The terminal device does not need to wait for the first satellite to return to the service link area to complete the user plane link restoration process, thereby reducing latency and power consumption of the terminal device.

[0182] The data transmission method provided in this application will be further described below with reference to Figures 4A and 4B. Figure 4A is a schematic flowchart of another data transmission method provided in an embodiment of this application. As shown in Figure 4A, wherein:

[0183] Procedure 401: The terminal device sends a random access preamble to the first satellite; the first satellite sends a random access response to the terminal device; the terminal device sends a first request to the first satellite; the first satellite sends an RRCConnectionResume to the terminal device; the terminal device restores the bearer, rebuilds AS security, and the UE enters the connected state; the terminal device sends an RRC connection restoration completion message to the first satellite. Correspondingly, the first satellite receives the random access preamble sent by the terminal device; the terminal device receives the random access response sent by the first satellite; the first satellite receives the first request sent by the terminal device; the terminal device receives the RRCConnectionResume message sent by the first satellite; the first satellite receives the RRC connection restoration completion message sent by the terminal device.

[0184] In step 401 of this process, the first satellite is located in the service link area. The first satellite communicates with the terminal device through the first service link.

[0185] Optionally, as shown in Figure 4B, the hollow satellite in Figure 4B is the first satellite, and the solid satellite is the second satellite. This process 401 corresponds to the first time point in Figure 4B. At the first time point, the first satellite is located in the service link area (the service link area corresponding to the terminal device), and the second satellite may or may not be located in the service link area.

[0186] Optionally, after procedure 401 is completed, the terminal device remains connected and waits for the satellite and core network to complete their interaction. The terminal device listens to the scheduling of the downlink control channel.

[0187] Procedure 402: The first satellite sends the first context information of the terminal device to the second satellite. Correspondingly, the second satellite receives the first context information of the terminal device sent by the first satellite.

[0188] Optionally, the first satellite can transmit the first context information of the terminal device to the second satellite via ISL. When the first satellite transmits the first context information of the terminal device to the second satellite, the first satellite may be located within the service link area or may have left the service link area.

[0189] Optionally, when the second satellite receives the first context information of the terminal device sent by the first satellite, the second satellite may already be in the feed link area, or the second satellite may not have yet entered the feed link area.

[0190] Optionally, as shown in Figure 4B, this process 402 corresponds to the second moment in Figure 4B.

[0191] Procedure 403: The second satellite sends a UE Context Resume Request to the MME; the MME sends Modify bearers to the S-GW; the MME sends a UE Context Resume Response to the second satellite. Correspondingly, the MME receives the UE Context Resume Request sent by the second satellite; the G-SW receives the Modify bearers sent by the MME; and the second satellite receives the UE Context Resume Response sent by the MME.

[0192] Optionally, when the second satellite interacts with the MME, the second satellite is located in the feed link region. For example, as shown in Figure 4B, this process 403 corresponds to the third moment in Figure 4B.

[0193] Procedure 404: The second satellite sends a scheduling signaling message to the terminal device, which instructs the terminal device to receive downlink data / send uplink data. In response to the scheduling signaling message, the terminal device sends uplink data / receives downlink data through the second service link. Accordingly, the terminal device receives the scheduling signaling message sent by the second satellite.

[0194] Optionally, when the second satellite interacts with the terminal device, the second satellite is located in the service link area, and a second service link exists between the second satellite and the terminal device. The second satellite and the terminal device can interact through the second service link. For example, as shown in Figure 4B, this process 404 corresponds to the fourth moment in Figure 4B.

[0195] Optionally, when the second satellite is located in the service link area, the terminal device can send uplink data to the second satellite through the second service link; or, the second satellite can send downlink data to the terminal device through the second service link.

[0196] After procedures 401-404 are completed, the user plane link is restored, and the terminal device enters the connected state. When the second satellite is in the service link area, the terminal device can transmit uplink / downlink data with the second satellite through the second service link.

[0197] Based on the above, another data transmission system provided by the embodiments of this application will be described in further detail below. As shown in FIG5A, the data transmission system includes the following steps: Step 1-Step 4. Wherein:

[0198] Step 1: The terminal device sends a first request to the first satellite, which requests the restoration of the radio resource control connection. The first satellite is located in the service link area. Correspondingly, the first satellite receives the first request sent by the terminal device.

[0199] Step 1 can be referred to in the description of Step 1 in Figure 3 above, and will not be repeated here. The first request can also be referred to in the description of the first request in Step 1 above. The first request in Figure 5A and the first request in Figure 3 can be the same request.

[0200] Step 2: After the first satellite enters the feed link area from the service link area, it sends a second request to the core network. This second request instructs the core network to modify and activate the bearer. Correspondingly, the core network receives the second request sent by the first satellite.

[0201] Optionally, the second request can be referred to in step 3 of Figure 3 above, and will not be repeated here. That is to say, in the embodiment of Figure 5A, the interaction is between the first satellite and the core network. The interaction between the first satellite and the core network is similar to the interaction between the second satellite and the core network, and can be referred to in the above description of the interaction between the second satellite and the core network.

[0202] Step 3: The first satellite sends the second context information of the terminal device to the second satellite. The second context information includes the information in the first request and the interaction results between the first satellite and the core network. Accordingly, the second satellite receives the second context information sent by the first satellite.

[0203] Optionally, the second context information includes the first context information, and the second context information also includes the interaction results between the first satellite and the core network.

[0204] In one possible embodiment, the first satellite determines the second satellite from among the multiple satellites in the network based on multiple ephemeris information corresponding to multiple satellites in the network. The second satellite is either the satellite that arrives at the service link area first in the network, or the second satellite is the satellite currently in the service link area in the network.

[0205] In one possible implementation, the ephemeris information includes position information and velocity information; the first satellite determines the second satellite from the multiple satellites in the network based on multiple ephemeris information corresponding to multiple satellites in the network, including: the first satellite determines the satellite that arrives at the service link area first in the network, or determines the satellite currently in the service link area in the network, based on multiple position information and multiple velocity information corresponding to multiple satellites in the network; the satellite that arrives at the service link area first, or the satellite currently in the service link area in the network, is determined as the second satellite.

[0206] The method by which the first satellite determines the satellite that arrives at the service link area first in the network based on multiple location information and multiple speed information corresponding to multiple satellites in the network can be found in the relevant description of step two in Figure 3 above, which will not be repeated here.

[0207] It should be noted that, in this embodiment, the interaction between the first satellite and the core network is completed by the first satellite, so the determined second satellite does not need to pass through the feeder link area after receiving the second context information.

[0208] Optionally, after the first satellite completes its interaction with the core network, it determines the second satellite from among the multiple satellites in the network based on multiple ephemeris information corresponding to multiple satellites in the network.

[0209] Optionally, the second satellite may send its ephemeris information to the first satellite via an inter-satellite link. This inter-satellite link is described above and will not be repeated here.

[0210] Optionally, the first satellite sends the second context information of the terminal device to the second satellite, including: the first satellite sends the second context information of the terminal device to the second satellite via an inter-satellite link.

[0211] Step 4: The second satellite sends a scheduling signaling message to the terminal device. The scheduling signaling message is used to instruct the terminal device to receive downlink data / send uplink data. The second satellite is located in the service link area. When the second satellite enters the service link area, the first satellite has not yet entered the service link area again.

[0212] This step can be referred to in the description of step 4 in Figure 3 above. It should be noted that when the second satellite enters the service link area, the first satellite has not yet re-entered the service link area. Specifically, this can mean that the time when the second satellite enters the service link area is earlier than the time when the first satellite re-enters the service link area, or that when the second satellite is in the service link area, the first satellite has not yet re-entered the service link area.

[0213] The data transmission method provided in this application will be further described below with reference to Figures 5B and 5C. Figure 5B is a schematic flowchart of another data transmission method provided in an embodiment of this application. As shown in Figure 5B, wherein:

[0214] Procedure 501: The terminal device sends a random access preamble to the first satellite; the first satellite sends a random access response to the terminal device; the terminal device sends a first request to the first satellite; the first satellite sends an RRCConnectionResume to the terminal device; the terminal device restores the bearer, rebuilds AS security, and the UE enters the connected state; the terminal device sends an RRC connection restoration completion message to the first satellite. Correspondingly, the first satellite receives the random access preamble sent by the terminal device; the terminal device receives the random access response sent by the first satellite; the first satellite receives the first request sent by the terminal device; the terminal device receives the RRCConnectionResume message sent by the first satellite; the first satellite receives the RRC connection restoration completion message sent by the terminal device.

[0215] This process 501 can be found in the description of process 401 above, and will not be repeated here.

[0216] Optionally, as shown in Figure 5C, the hollow satellite in Figure 5C is the first satellite, and the solid satellite is the second satellite. This procedure 501 corresponds to the first time point in Figure 5C.

[0217] Procedure 502: The first satellite sends a UE Context Resume Request to the MME; the MME sends Modify bearers to the S-GW; the MME sends a UE Context Resume Response to the first satellite. Correspondingly, the MME receives the UE Context Resume Request sent by the first satellite; the G-SW receives the Modify bearers sent by the MME; and the first satellite receives the UE Context Resume Response sent by the MME.

[0218] This process 502 can be found in the description of process 403 above. Unlike process 403, in the embodiment of Figure 5B, the interaction is completed by the first satellite and the core network. In this process 502, the first satellite passes through the feed link area.

[0219] Optionally, as shown in Figure 5C, this procedure 502 corresponds to the second time point in Figure 5C. It should be noted that when performing procedure 502, the second satellite may have passed through the service link area or may not have yet entered the service link area.

[0220] Procedure 503: The first satellite sends the second context information of the terminal device to the second satellite. Correspondingly, the second satellite receives the second context information of the terminal device sent by the first satellite.

[0221] This process 503 can be referred to in the description of process 402 above. It should be noted that the context information of the terminal in process 503 may differ from the context information of the terminal in process 402. Since, in the embodiment shown in Figure 5B, the interaction is between the first satellite and the core network, when the first satellite sends the second context information to the second satellite, it needs to carry the relevant results of the interaction between the first satellite and the core network to ensure subsequent data transmission between the second satellite and the terminal device. Optionally, the second context information includes the relevant results of the core network interaction.

[0222] Optionally, as shown in Figure 5C, this process 502 corresponds to the third moment in Figure 5C.

[0223] Procedure 504: The second satellite sends a scheduling signaling message to the terminal device, which instructs the terminal device to receive downlink data / send uplink data. In response to the scheduling signaling message, the terminal device sends uplink data / receives downlink data through the second service link. Accordingly, the terminal device receives the scheduling signaling message sent by the second satellite.

[0224] This process 504 can be found in the description of process 404 above.

[0225] For example, as shown in Figure 5C, this process 504 corresponds to the fourth moment in Figure 5C.

[0226] Please refer to Figure 6, which shows a schematic diagram of the structure of a communication device 600 according to an embodiment of this application. The communication device shown in Figure 6 can be a terminal device / first satellite / second satellite. It can also be a device in the terminal device / first satellite / second satellite, or a device that can be used in conjunction with the terminal device / first satellite / second satellite. Specifically, as shown in Figure 6, the communication device 600 may include a communication unit 601. The communication unit 601 is used for communication. Optionally, the communication unit 601 integrates a receiving unit and a transmitting unit. The communication unit 601 can also be called a transceiver unit. Alternatively, the communication unit 601 can be split into a receiving unit and a transmitting unit.

[0227] In one embodiment, the communication device 600 may be a terminal device, a device within a terminal device, or a device compatible with a terminal device, wherein:

[0228] Communication unit 601 is used to send a first request to a first satellite, the first request being used to request the restoration of radio resource control connection, the first satellite being located in the service link area;

[0229] The communication unit 601 is also used to receive scheduling signaling sent by the second satellite. The scheduling signaling is used to instruct the terminal equipment to receive downlink data / send uplink data. The second satellite enters the service link area from the feed link area earlier than the first satellite re-enters the service link area.

[0230] In one embodiment, the communication device 600 may be a first satellite, a device within the first satellite, or a device compatible with the first satellite, wherein:

[0231] Communication unit 601 is used to receive a first request sent by terminal device, the first request being used to request the restoration of radio resource control connection, and the first satellite being located in the service link area;

[0232] The communication unit 601 is also used to send first context information of the terminal device to the second satellite, the first context information including at least the information in the first request.

[0233] In one embodiment, the communication device 600 may be a second satellite, a device within a second satellite, or a device compatible with a first satellite, wherein:

[0234] The communication unit 601 receives first context information of the terminal device transmitted by the first satellite, the first context information including information in the first request;

[0235] The communication unit 601 is also used to send a second request to the core network, the second request being used to instruct the core network to modify and activate the bearer;

[0236] The communication unit 601 is also used to send scheduling signaling to the terminal device, which instructs the terminal device to receive downlink data / send uplink data.

[0237] Figure 7 shows a schematic diagram of another communication device. The communication device 700 can be the terminal device / first satellite / second satellite in the above method embodiments, or it can be a chip, chip system, or processor that supports the terminal device / first satellite / second satellite in implementing the above methods. This communication device can be used to implement the methods described in the above method embodiments; for details, please refer to the descriptions in the above method embodiments.

[0238] The communication device 700 may include one or more processors 701. The processor 701 may be a general-purpose processor or a dedicated processor, such as a baseband processor or a central processing unit (CPU). The baseband processor can be used to process communication protocols and communication data, while the CPU can be used to control the communication device (e.g., base station, baseband chip, terminal, terminal chip, DU or CU, etc.), execute software programs, and process data from the software programs.

[0239] Optionally, the communication device 700 may include one or more memories 702, which may store instructions 704 that can be executed on the processor 701, causing the communication device 700 to perform the methods described in the above method embodiments. Optionally, the memory 702 may also store data. The processor 701 and the memory 702 may be provided separately or integrated together.

[0240] Optionally, the communication device 700 may further include a transceiver 705 and an antenna 706. The transceiver 705, which may be referred to as a transceiver unit, transceiver, or transceiver circuit, is used to implement transceiver functions. The transceiver 705 may include a receiver and a transmitter. The receiver, which may be referred to as a receiver or receiving circuit, is used to implement a receiving function; the transmitter, which may be referred to as a transmitter or transmitting circuit, is used to implement a transmitting function. The communication unit 601 may be the transceiver 705.

[0241] In another possible design, the processor 701 may include a transceiver for implementing receive and transmit functions. For example, the transceiver may be a transceiver circuit, an interface, or an interface circuit. The transceiver circuit, interface, or interface circuit for implementing receive and transmit functions may be separate or integrated. The aforementioned transceiver circuit, interface, or interface circuit can be used for reading and writing code / data, or it can be used for transmitting or relaying signals.

[0242] In another possible design, the processor 701 may optionally store instructions 703, which, when executed on the processor 701, cause the communication device 700 to perform the methods described in the above method embodiments. Instructions 703 may be embedded in the processor 701; in this case, the processor 701 may be implemented in hardware.

[0243] In another possible design, the communication device 700 may include circuitry that can perform the functions of sending, receiving, or communicating as described in the foregoing method embodiments. The processor and transceiver described in this application embodiment can be implemented on integrated circuits (ICs), analog ICs, radio frequency integrated circuits (RFICs), mixed-signal ICs, application-specific integrated circuits (ASICs), printed circuit boards (PCBs), electronic devices, etc. The processor and transceiver can also be manufactured using various IC process technologies, such as complementary metal oxide semiconductors (CMOS), n-metal-oxide-semiconductor (NMOS), positive-channel metal oxide semiconductors (PMOS), bipolar junction transistors (BJTs), bipolar CMOS (BiCMOS), silicon germanium (SiGe), gallium arsenide (GaAs), etc.

[0244] The communication device described in the above embodiments can be a terminal device / first satellite / second satellite, but the scope of the communication device described in the embodiments of this application is not limited to this, and the structure of the communication device is not limited to FIG. 7. The communication device can be a standalone device or can be part of a larger device. For example, the communication device can be:

[0245] (1) Independent integrated circuit IC, or chip, or chip system or subsystem;

[0246] (2) A collection of one or more ICs, optionally including a storage component for storing data and instructions;

[0247] (3) ASIC, such as modem (MSM);

[0248] (4) Modules that can be embedded in other devices;

[0249] (5) Receivers, terminals, smart terminals, cellular phones, wireless devices, handheld devices, mobile units, vehicle-mounted devices, network devices, cloud devices, artificial intelligence devices, etc.

[0250] (6) Others, etc.

[0251] For communication devices that can be chips or chip systems, please refer to the schematic diagram of the chip structure shown in Figure 8. The chip 800 shown in Figure 8 includes a processor 801 and an interface 802. Optionally, it may also include a memory 803. The number of processors 801 can be one or more, and the number of interfaces 802 can be multiple.

[0252] For cases where the chip is used to implement the terminal device or network device in the embodiments of this application:

[0253] The interface 802 is used to receive or output signals;

[0254] The processor 801 is used to perform data processing operations on terminal devices or network devices.

[0255] It is understood that some optional features in the embodiments of this application can be implemented independently in certain scenarios without relying on other features, such as the current solution on which they are based, to solve the corresponding technical problems and achieve the corresponding effects. Alternatively, they can be combined with other features as needed in certain scenarios. Accordingly, the communication device given in the embodiments of this application can also implement these features or functions, which will not be elaborated here.

[0256] It should be understood that the processor in the embodiments of this application can be an integrated circuit chip with signal processing capabilities. In implementation, the steps of the above method embodiments can be completed by integrated logic circuits in the processor's hardware or by instructions in software form. The processor described above can be a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components.

[0257] It is understood that the memory in the embodiments of this application can be volatile memory or non-volatile memory, or may include both volatile and non-volatile memory. The non-volatile memory can be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. The volatile memory can be random access memory (RAM), which is used as an external cache. By way of example, but not limitation, many forms of RAM are available, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous linked dynamic random access memory (SLDRAM), and direct rambus RAM (DR RAM). It should be noted that the memory used in the systems and methods described herein is intended to include, but is not limited to, these and any other suitable types of memory.

[0258] This application also provides a computer-readable medium storing a computer program or instructions, which, when executed by a communication device, implements the functions of any of the above method embodiments.

[0259] This application also provides a computer program product including instructions, which, when read and executed by a computer, causes the computer to perform the functions of any of the above method embodiments.

[0260] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented, in whole or in part, as a computer program product. The computer program product includes one or more computer instructions. When the computer instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium accessible to a computer or a data storage device such as a server or data center that integrates one or more available media. The available media may be magnetic media (e.g., floppy disks, hard disks, magnetic tapes), optical media (e.g., high-density digital video discs (DVDs)), or semiconductor media (e.g., solid-state disks (SSDs)).

[0261] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

A data transmission system, characterized in that, Including terminal equipment, the first satellite, and the second satellite. The terminal device sends a first request to the first satellite, the first request being used to request the restoration of the radio resource control connection, the first satellite being located in the service link area; The first satellite sends the first context information of the terminal device to the second satellite, the first context information including the information in the first request; The second satellite sends a second request to the core network, the second request being used to instruct the core network to modify and activate the bearer, the second satellite being located in the feed link region, and the second request including the first context information; After the second satellite enters the service link area from the feed link area, the second satellite sends a scheduling signaling to the terminal device. The scheduling signaling is used to instruct the terminal device to receive downlink data / send uplink data. The second satellite enters the service link area from the feed link area earlier than the first satellite re-enters the service link area. The system according to claim 1, characterized in that, The first satellite determines the second satellite from among the multiple satellites in the network based on multiple ephemeris information corresponding to multiple satellites in the network. The second satellite is the first satellite in the network to arrive at the service link area. The system according to claim 2 is characterized in that, The ephemeris information includes position information and velocity information; The first satellite determines the second satellite from multiple satellites in the network based on multiple ephemeris information corresponding to multiple satellites in the network, including: The first satellite determines the satellite that arrives at the service link area first in the network based on multiple location information and multiple speed information corresponding to multiple satellites in the network. The satellite that first arrives at the service link area is designated as the second satellite. The system according to claim 2 or 3 is characterized in that, The second satellite sends its ephemeris information to the first satellite via an inter-satellite link. The system according to claim 2 or 3 is characterized in that, The first satellite sends the first context information of the terminal device to the second satellite, including: the first satellite sends the first context information of the terminal device to the second satellite via an inter-satellite link. The system according to any one of claims 1-3 is characterized in that, The information in the first request includes one or more of the following: recovery identifier, recovery reason, and recovery parameters. A data transmission system, characterized in that, Including terminal equipment, the first satellite, and the second satellite. The terminal device sends a first request to the first satellite, the first request being used to request the restoration of the radio resource control connection, the first satellite being located in the service link area; After the first satellite enters the feed link area from the service link area, the first satellite sends a second request to the core network. The second request is used to instruct the core network to modify and activate the bearer. The first satellite sends the second context information of the terminal device to the second satellite. The second context information includes the information in the first request and the interaction result between the first satellite and the core network. The second satellite sends a scheduling signaling message to the terminal device, the scheduling signaling message being used to instruct the terminal device to receive downlink data / send uplink data, the second satellite being located in the service link area; When the second satellite enters the service link area, the first satellite has not yet entered the service link area again. The system according to claim 7 is characterized in that, The first satellite determines the second satellite from among the multiple satellites in the network based on multiple ephemeris information corresponding to multiple satellites in the network. The second satellite is either the first satellite in the network to arrive at the service link area, or the second satellite is a satellite in the network that is currently in the service link area. The system according to claim 8, characterized in that, The ephemeris information includes position information and velocity information; The first satellite determines the second satellite from multiple satellites in the network based on multiple ephemeris information corresponding to multiple satellites in the network, including: The first satellite determines the satellite that arrives at the service link area first in the network, or determines the satellite currently in the service link area in the network, based on multiple location information and multiple speed information corresponding to multiple satellites in the network. The satellite that arrives first in the service link area, or the satellite currently in the service link area in the network, is identified as the second satellite. The system according to claim 8 or 9 is characterized in that, The second satellite sends its ephemeris information to the first satellite via an inter-satellite link. The system according to claim 8 or 9 is characterized in that, The first satellite sends the second context information of the terminal device to the second satellite, including: the first satellite sends the second context information of the terminal device to the second satellite via an inter-satellite link. The system according to any one of claims 7-9 is characterized in that, The first request includes one or more of the following information: recovery identifier, recovery reason, and recovery parameters.

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