Data transmission method, terrestrial network element, terminal, on-satellite network element, and storage medium

Abstract

The present application relates to a data transmission method, a terrestrial network element, a terminal, an on-satellite network element, and a storage medium. The method is applied to a terrestrial MME. The method comprises: on the basis of satellite identifier monitoring list information of a terminal available for data transmission, determining a first satellite identifier of a next satellite to reach the terminal first; and when a satellite feeder link corresponding to the first satellite identifier is available, sending downlink data to a first on-satellite MME corresponding to the first satellite identifier.

Description

Data transmission method, ground network element, terminal, on-board network element and storage medium

[0001] The present application claims priority to the Chinese patent application No. 2024110944408, filed on August 9, 2024, and entitled “Data transmission method, ground network element, terminal, on-board network element and storage medium”, the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present application relates to the field of communication technology, and in particular to a data transmission method, a ground network element, a terminal, an on-board network element and a storage medium. BACKGROUND

[0003] For the Internet of Things-Non-Terrestrial Network (IoT-NTN) technology of medium and low earth orbit, in the early stage of network construction, due to the limited number of satellites and gateway stations, the service link and feeder link of the satellite cannot be available at the same time. This will cause the IoT-NTN to be unable to provide communication services for terminals within the satellite coverage range at some time. In view of this situation, the industry is researching IoT-NTN store-and-forward technology based on medium and low earth orbit satellite regeneration mode.

[0004] At present, the IoT-NTN store-and-forward technology standard of 3GPP R19 (3rd Generation Partnership Project Release 19) has not been determined, and some technical problems of some scenarios need to be solved. For example, in a multi-satellite scenario, how does a terminal send uplink data through different satellites, and how does the downlink data of an application be sent to a user terminal through different satellites. SUMMARY

[0005] Therefore, it is necessary to provide a data transmission method, a ground network element, a terminal, an on-board network element and a storage medium capable of realizing data transmission in a multi-satellite scenario to solve the above technical problems.

[0006] In a first aspect, the present application provides a data transmission method applied to a ground MME, the method comprising:

[0007] determining a first satellite identifier of a satellite that can first reach the terminal according to satellite identifier monitoring list information of the terminal available for data transmission;

[0008] when a satellite feeder link corresponding to the first satellite identifier is available, sending downlink data to a first on-board MME corresponding to the first satellite identifier.

[0009] In a second aspect, a data transmission method is provided, applied to an SCEF or an SGW, and the method comprises:

[0010] receiving a storage instruction sent by a ground MME and storing downlink data, wherein the storage instruction is used to instruct to store the downlink data;

[0011] sending the downlink data to the ground MME.

[0012] In a third aspect, a data transmission method is provided, applied to an SCS or an AS, and the method comprises:

[0013] sending downlink data to an SCEF or an SGW;

[0014] receiving a waiting time of an acknowledgement message for the downlink data sent by the SCEF or the SGW;

[0015] starting a first timer, wherein a time limit of the first timer is set based on the waiting time.

[0016] In a fourth aspect, a data transmission method is provided, applied to a terminal, and the method comprises:

[0017] when it is determined that there is uplink data to be transmitted, listening to a SIB message, wherein the SIB message comprises a second satellite identity;

[0018] when the second satellite identity is included in satellite identity listening list information of the terminal available for data transmission, sending uplink data to a second satellite corresponding to the second satellite identity.

[0019] In a fifth aspect, a data transmission method is provided, applied to a second satellite MME, and the method comprises:

[0020] receiving uplink data sent by a terminal and saving the uplink data;

[0021] when a satellite feeder link corresponding to the second satellite MME is available, sending the uplink data to a ground MME.

[0022] In a sixth aspect, a ground MME is provided, comprising a memory, a transceiver, and a processor:

[0023] the memory is used to store a computer program; the transceiver is used to transceive data under control of the processor; and the processor is used to read the computer program in the memory and execute the method according to the first aspect.

[0024] In a seventh aspect, an SCEF or an SGW is provided, comprising a memory, a transceiver, and a processor:

[0025] The memory is configured to store a computer program; the transceiver is configured to transceive data under control of the processor; and the processor is configured to read the computer program in the memory and perform the method of the second aspect.

[0026] In an eighth aspect, an SCS or AS is provided, comprising: a memory, a transceiver, and a processor.

[0027] The memory is configured to store a computer program; the transceiver is configured to transceive data under control of the processor; and the processor is configured to read the computer program in the memory and perform the method of the third aspect.

[0028] In a ninth aspect, a terminal is provided, comprising: a memory, a transceiver, and a processor.

[0029] The memory is configured to store a computer program; the transceiver is configured to transceive data under control of the processor; and the processor is configured to read the computer program in the memory and perform the method of the fourth aspect.

[0030] In a tenth aspect, a second on-board MME is provided, comprising: a memory, a transceiver, and a processor.

[0031] The memory is configured to store a computer program; the transceiver is configured to transceive data under control of the processor; and the processor is configured to read the computer program in the memory and perform the method of the fifth aspect.

[0032] In an eleventh aspect, a ground MME is provided, comprising:

[0033] A determining module is configured to determine, according to satellite identifier listening list information available for data transmission of a terminal, a first satellite identifier that is first available to reach the terminal;

[0034] A sending module is configured to send, to a first on-board MME corresponding to the first satellite identifier, downlink data when a satellite feeder link corresponding to the first satellite identifier is available.

[0035] In a twelfth aspect, an SCEF or SGW is provided, comprising:

[0036] A receiving module is configured to receive a storage indication sent by a ground MME and store downlink data, wherein the storage indication is used to indicate storage of the downlink data.

[0037] A sending module is configured to send the downlink data to the ground MME.

[0038] In a thirteenth aspect, an SCS or AS is provided, comprising:

[0039] The sending module is configured to send downlink data to the SCEF or the SGW;

[0040] The receiving module is configured to receive a waiting time of an acknowledgement message for the downlink data sent by the SCEF or the SGW.

[0041] The timing module is configured to start a first timer, wherein a time limit of the first timer is set based on the waiting time.

[0042] In a fourteenth aspect, a terminal is provided, comprising a memory, a transceiver, and a processor.

[0043] The receiving module is configured to receive a SIB message, wherein the SIB message comprises a second satellite identifier.

[0044] The sending module is configured to send uplink data to a second satellite corresponding to the second satellite identifier when the second satellite identifier is included in a satellite identifier listening list information of the terminal available for data transmission.

[0045] In a fifteenth aspect, a second satellite MME is provided, comprising a memory, a transceiver, and a processor.

[0046] The receiving module is configured to receive uplink data sent by a terminal and save the uplink data.

[0047] The sending module is configured to send the uplink data to a ground MME when a satellite feeder link corresponding to the second satellite MME is available.

[0048] In a sixteenth aspect, a computer readable storage medium is provided, wherein the computer readable storage medium stores a computer program, and the computer program is executed by a processor to implement at least one of the methods described above.

[0049] The method of the first aspect, the method of the second aspect, the method of the third aspect, the method of the fourth aspect, or the method of the fifth aspect.

[0050] In a seventeenth aspect, a computer program product is provided, wherein the computer program product comprises a computer program, and the computer program is executed by a processor to implement at least one of the methods described above.

[0051] The method of the first aspect, the method of the second aspect, the method of the third aspect, the method of the fourth aspect, or the method of the fifth aspect.

[0052] The ground MME, the SCEF, the SCS, the AS, the SGW, and the PGW are all ground network elements, and the first satellite MME and the second satellite MME are both satellite network elements.

[0053] The data transmission method, the ground MME can determine the first satellite identifier of the next first reachable terminal according to the satellite identifier listening list information available for data transmission of the terminal, and send the downlink data to the first satellite MME corresponding to the first satellite identifier when the satellite feeder link corresponding to the first satellite identifier is available. In this way, in the multi-satellite scenario, the satellite used for downlink transmission can be determined based on the satellite identifier listening list information, thereby realizing downlink transmission in the multi-satellite scenario.

[0054] The data transmission method, when the terminal determines that there is uplink data to be transmitted, the terminal can acquire the second satellite identifier included in the SIB message by listening to the SIB message; and when the second satellite identifier is included in the satellite identifier listening list information available for data transmission of the terminal, the terminal can send the uplink data to the second satellite MME corresponding to the second satellite identifier. In this way, in the multi-satellite scenario, the satellite used for uplink transmission can be determined through the SIB message and the satellite identifier listening list information, thereby realizing uplink transmission in the multi-satellite scenario. BRIEF DESCRIPTION OF DRAWINGS

[0055] FIG. 1 is a flow diagram of a downlink data transmission method according to an embodiment of the present application;

[0056] FIG. 2 is a flow diagram of a non-IP type downlink data transmission method;

[0057] FIG. 3 is a flow diagram of an IP type downlink data transmission method;

[0058] FIG. 4 is a flow diagram of an uplink data transmission method according to an embodiment of the present application;

[0059] FIG. 5 is a flow diagram of a non-IP type uplink data transmission method;

[0060] FIG. 6 is a flow diagram of an IP type uplink data transmission method;

[0061] FIG. 7 is a structural diagram of a communication device according to an embodiment of the present application;

[0062] FIG. 8 is a structural block diagram of a ground MME;

[0063] FIG. 9 is a structural block diagram of a SCEF or SGW;

[0064] FIG. 10 is a structural block diagram of a SCS or AS;

[0065] FIG. 11 is a structural block diagram of a terminal;

[0066] FIG. 12 is a structural block diagram of a second satellite MME. DETAILED DESCRIPTION

[0067] In order to make the purposes, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and should not be used to limit the present application.

[0068] The term "and / or" in the embodiments of the present application describes the association relationship of the associated objects, which means that there can be three kinds of relationships, for example, A and / or B can represent the following three cases: A exists alone, A and B exist together, and B exists alone. The character " / " generally represents that the associated objects before and after it are in an "or" relationship.

[0069] Narrowband Internet of Things-Non-Terrestrial Network (IoT-NTN) is a Long Term Evolution (LTE) network mobile communication system supporting access through satellites based on the Narrow Band Internet of Things (NB-IoT) technical standard. Among them, the access through satellites can be a satellite transparent mode or a satellite regenerative mode. The present patent application relates to the satellite regenerative mode.

[0070] For IoT-NTN in the satellite regenerative mode, the entire system is composed of terminals, satellite regenerative payloads (such as evolved Node B (eNodeB), Mobility Management Entity (MME), Serving Gateway (SGW), satellite gateway, core network and service server, etc.). According to different networking situations, the functions included in the satellite regenerative payload will be different, which can have evolved Node B (eNodeB) network element function, or evolved Node B (eNodeB) and Mobility Management Entity (MME) network element function, etc. The system focuses on supporting satellite Internet of Things services for low-complexity enhanced Machine Type Communication (eMTC) and Internet of Things terminals, and mainly aims at scenarios such as sea transportation, energy collection, global asset tracking and environmental monitoring, to provide reliable data transmission services for various low-rate, low-frequency and low-cost Internet of Things applications.

[0071] For IoT-NTN technology in low-orbit, in the initial stage of network construction, due to the limited number of satellites and gateway stations, the service link and feeder link of the satellite cannot be used at the same time, which leads to the fact that IoT-NTN cannot provide communication services for terminals in the coverage of the satellite at some time.

[0072] In view of this situation, the industry is researching IoT-NTN storage forwarding technology based on low-orbit satellite regeneration mode. The basic technical idea is that when the service link is available and the feeder link is unavailable, the on-board network element can communicate with the terminal, receive the message sent by the terminal in the coverage, cache it on the on-board network element, and forward the cached message from the ground network to the terminal; when the feeder link is available and the service link is unavailable, the on-board network element can communicate with the ground network through the gateway station, transmit the terminal message cached on the satellite back to the ground, and receive the message sent by the ground network to the terminal and cache it on the on-board network element. This technology can be widely applied to the Internet of Things scenarios with non-real-time communication requirements.

[0073] At present, the IoT-NTN storage forwarding technology standard of the 3rd Generation Partnership Project (3GPP) R19 has not been determined, and the related scheme is still in the research stage, and some technical problems in some scenarios still need to be solved, such as in a multi-satellite scenario, how does the terminal send uplink data through different satellites, and how does the application downlink data sent to the user terminal through different satellites, so as to achieve load balancing of different satellites or different satellites serving different IoT-NTN applications.

[0074] In order to solve the above problems, the present application proposes a data transmission method which can be applied in single-satellite or multi-satellite scenarios. When the terminal needs to send uplink data, the terminal listens to the satellite signal in the satellite identification listening list information and sends uplink data; when the network side device needs to send downlink data to the terminal, it can perform corresponding downlink data transmission according to the satellite identification listening list information available for data transmission of the terminal. This scheme can realize uplink and downlink data transmission in single-satellite or multi-satellite scenarios, and can realize load balancing of different storage forwarding satellites and terminal energy saving purposes.

[0075] The related functional network elements involved in the embodiments of the present application include:

[0076] 1) Terminal: support network access and data transmission functions in non-terrestrial network (Non-Terrestrial Network, NTN) storage forwarding scenarios.

[0077] 2) Onboard Mobility Management Function Entity (MME): a Mobility Management Function Entity located on the satellite, which is a functional subset of the Mobility Management Function Entity, receives and forwards NAS signaling / data messages, buffers Non-Access Stratum (NAS) signaling / data messages, and the like. When the service link is available, it receives and buffers uplink NAS signaling / data messages from the terminal, and forwards the buffered downlink NAS signaling / data messages to the terminal; when the feeder link is available, it forwards the buffered uplink NAS signaling / data messages to the ground Mobility Management Function Entity (ground MME), and receives downlink NAS signaling / data messages from the ground Mobility Management Function Entity (ground MME) and buffers them.

[0078] 3) Ground Mobility Management Function Entity (ground MME): a Mobility Management Function Entity located on the ground, which has all the functions of the Mobility Management Function Entity, is responsible for the mobility management, access control, bearer management, session management, and NAS signaling processing of the terminal, and the like. It has the function of determining the routing of downlink data according to the terminal location information and the list of satellite Identity (ID) information available for the data transmission of the terminal, and the function of synchronizing the User Equipment (UE) context information with the onboard MME. In the MME separation architecture, the ground MME has the function of a ground anchor network element.

[0079] 4) SCEF functional entity: an abbreviation of Service Capability Exposure Function, which has the functions of monitoring the state of IoT devices, forwarding non-Internet Protocol (non-IP) type data, and the like.

[0080] 5) SCS functional entity: an abbreviation of Service Capability Server.

[0081] 6) AS functional entity: an abbreviation of Application Server.

[0082] 7) SGW: Serving Gateway, the SGW can be responsible for routing and forwarding of user plane data. It is a key network element in the core network that connects the eNodeB (base station) and the packet data network gateway (PDN Gateway, PGW). The SGW can handle handover between different base stations, ensuring the continuity of user data during movement. For example, when a user moves from one base station coverage area to another, the SGW is responsible for switching the user's data transmission path to ensure uninterrupted data transmission.

[0083] 8) PGW: PDN Gateway, the PGW is a gateway that connects external data networks (such as the Internet) and the mobile core network. It is responsible for allocating IP addresses for users, charging and policy control, and performing functions such as packet filtering and deep packet inspection. For example, when a user accesses the Internet, the PGW will control data traffic and billing according to the user's package and network policy, and ensure the safe transmission of data.

[0084] The data transmission method provided by the embodiments of the present application includes an uplink data transmission method and a downlink data transmission method. The two data transmission methods will be introduced below.

[0085] For example, FIG. 1 is a flowchart of a downlink data transmission method provided by an embodiment of the present application. The method can include but is not limited to the following steps:

[0086] Step S11, the ground MME determines the first satellite identity of the next first reachable terminal according to the terminal's satellite identity listening list information available for data transmission.

[0087] Among them, the first satellite identity of the next first reachable terminal refers to the identity of the satellite that will first be able to establish an effective communication connection with the terminal among a series of satellites available for data transmission with the terminal.

[0088] In some embodiments, the ground MME can determine the first satellite identity of the next first reachable terminal according to the terminal's location information and the terminal's satellite identity listening list information available for data transmission.

[0089] Since the terminal's location information may change, determining the first satellite identity of the next first reachable terminal according to the terminal's location information and the terminal's satellite identity listening list information available for data transmission takes into account the change in the terminal's location, making the obtained first satellite identity of the next first reachable terminal more accurate.

[0090] In some embodiments, the terminal can determine the satellite identification monitoring list information available for data transmission according to the first information. The first information includes at least one of the following:

[0091] The subscription data of the terminal, satellite ephemeris information, location information of the terminal, and MME default configuration information.

[0092] The subscription data of the terminal is data information related to the service package, permission, priority, etc. subscribed by the user of the terminal. For example, whether the user subscribes to a low-latency data service or a high-latency data service, whether there is a use permission for a specific satellite, etc.

[0093] The satellite ephemeris information describes the detailed space-time parameters of the satellite, such as the orbit, position, speed, and transit time of the satellite, which helps to predict the position and coverage range of the satellite at different time points.

[0094] The location information of the terminal refers to the current geographical position of the terminal, which is very important for determining which satellite can first cover and establish a connection with the terminal.

[0095] The MME default configuration information is some default configuration parameters preset by the MME. For example, the default satellite selection strategy and priority rule.

[0096] For example, if the location information of the terminal shows that it is moving quickly, in combination with the satellite ephemeris information, it can be more accurately determined which satellite will first reach the location of the terminal and provide service. The subscription data of the terminal may determine which satellites can be used. The MME default configuration information may specify that a certain type of satellite is preferred in certain specific situations.

[0097] Step S12: When the satellite feeder link corresponding to the first satellite identification is available, the ground MME sends downlink data to the first satellite identification corresponding to the first satellite MME.

[0098] The first satellite MME is a satellite network element.

[0099] The satellite feeder link corresponding to the first satellite identification is the link between the ground MME and the first satellite MME. The first satellite MME can be an MME deployed on the first satellite corresponding to the first satellite identification.

[0100] The data transmission method, the ground MME can determine the first satellite identifier of the next first reachable terminal according to the satellite identifier listening list information available for data transmission of the terminal, and send the downlink data to the first satellite on MME corresponding to the first satellite identifier when the satellite feeder link corresponding to the first satellite identifier is available. In this way, in a multi-satellite scenario, the satellite used for downlink transmission can be determined based on the satellite identifier listening list information, thereby realizing downlink transmission in a single-satellite or multi-satellite scenario.

[0101] In the embodiments of the present application, the downlink data transmission method includes a non-Internet Protocol (non-IP) type downlink data transmission method and an Internet Protocol (IP) type downlink data transmission method. In order to more clearly illustrate the downlink data transmission method in the embodiments of the present application, the non-IP type downlink data transmission method and the IP type downlink data transmission method will be described below.

[0102] (1) non-IP type downlink data transmission method.

[0103] In some embodiments, when the satellite feeder link corresponding to the first satellite identifier is available, the ground MME can send a downlink data transmission instruction to the SCEF, receive the downlink data sent by the SCEF, and send the downlink data to the first satellite on MME.

[0104] In some embodiments, before the ground MME sends the downlink data to the first satellite on MME corresponding to the first satellite identifier, the ground MME can receive the downlink data sent by the SCEF through a service capability server (SCS). The ground MME can also determine the waiting time for the SCS to receive an acknowledgement message for the downlink data; and send the waiting time to the SCS through the SCEF.

[0105] That is, the SCS sends the downlink data to the SCEF, and after the SCEF receives the downlink data sent by the SCS, the SCEF can send the downlink data to the ground MME.

[0106] In some embodiments, before the ground MME sends the downlink data to the first satellite on MME corresponding to the first satellite identifier, the ground MME can receive the downlink data sent by the SCEF through an application server (AS). The ground MME can also determine the waiting time for the AS to receive an acknowledgement message for the downlink data; and send the waiting time to the AS through the SCEF.

[0107] That is, the AS sends downlink data to the SCEF, and after the SCEF receives the downlink data sent by the AS, the SCEF can send the downlink data to the ground MME.

[0108] The ground MME can estimate the waiting time of the SCS or the AS to receive the acknowledgement message for the downlink data after the SCS or the AS sends the downlink data, and inform the SCS or the AS. The ground MME can send the waiting time line to the SCEF, and the SCEF forwards the waiting time line to the SCS or the AS.

[0109] In some embodiments, after the SCS or the AS receives the waiting time, the SCS or the AS can start a first timer, and the time limit of the first timer is set based on the waiting time. For example, the implementation of the first timer can be set to be equal to the waiting time.

[0110] In some embodiments, when the acknowledgement message is not received when the first timer expires, it means that the downlink data transmission fails at this time, and the downlink data is re-sent to the SCEF or the SGW at this time; when the acknowledgement message is received within the time limit of the first timer, it means that the downlink data has been successfully transmitted at this time, and the first timer can be cancelled at this time.

[0111] In some embodiments, before the ground MME sends the downlink data to the first satellite-identified corresponding first satellite-borne MME, when the first satellite-identified corresponding satellite feeder link is unavailable, the ground MME can save the downlink data. Since the first satellite-identified corresponding satellite feeder link is currently unavailable, the downlink data needs to be sent when the first satellite-identified corresponding satellite feeder link is available, so the downlink data needs to be saved first.

[0112] In some embodiments, when the ground MME does not have a data storage function, or the storage space is insufficient to store the downlink data, the ground MME sends a storage indication to the SCEF, and the storage indication is used to indicate the storage of the downlink data. That is, in the case that the ground MME cannot store the downlink data, the SCEF can be instructed to store the downlink data through the storage indication.

[0113] In some embodiments, the SCEF can receive the storage indication sent by the ground MME and store the downlink data. When the first satellite-identified corresponding satellite feeder link is available, the ground MME can obtain the downlink data from the SCEF, and the SCEF sends the downlink data to the ground MME.

[0114] In some embodiments, when the first satellite-identified corresponding satellite feeder link is available, a downlink data sending indication is sent to the SCEF, the downlink data sent by the SCEF is received, and the downlink data is sent to the first satellite-borne MME.

[0115] In some embodiments, after the SCEF sends the downlink data to the ground MME, the SCEF can delete the stored downlink data.

[0116] For example, FIG. 2 is a flowchart of a non-IP type downlink data transmission method. As shown in FIG. 2, the method includes but is not limited to the following steps:

[0117] Step S101, the terminal sends an attach request message to the ground MME.

[0118] In some embodiments, the above step S101 can also be replaced by the terminal sending a TAU request message to the ground MME.

[0119] Step S102, the ground MME determines the satellite identification monitoring list information available for data transmission of the terminal according to the first information.

[0120] The first information includes at least one of the following:

[0121] The terminal's subscription data, satellite ephemeris information, the terminal's location information, and MME default configuration information.

[0122] In some embodiments, after receiving the attach request message, the ground MME can determine the satellite identification monitoring list information based on the above step S102 after the necessary authentication process.

[0123] The satellite identification monitoring list information is a list of satellite IDs available for data transmission of the terminal being monitored.

[0124] Step S103, the ground MME sends an attach accept message to the terminal, and the attach accept message carries the satellite identification monitoring list information available for data transmission of the terminal.

[0125] In some embodiments, in the case where the above step S101 is replaced by the terminal sending a TAU request message to the ground MME, the above step S103 can be replaced by: the ground MME sends a TAU accept message to the terminal, and the TAU accept message carries the satellite identification monitoring list information available for data transmission of the terminal.

[0126] Step S104, the terminal saves the satellite identification monitoring list information available for data transmission of the terminal.

[0127] Step S105, the ground MME synchronizes the terminal context information to the on-board MMEs within the range indicated by the satellite identification monitoring list information in sequence when the feeder link is available.

[0128] Step S201, the SCS / AS sends downlink data to the SCEF through a Non-IP Data Delivery Submit Request message.

[0129] The SCS / AS is a ground network element.

[0130] The SCS / AS can send a NIDD Submit Request message to the SCEF, and the NIDD Submit Request message carries the downlink data.

[0131] Step S202, the SCEF forwards the NIDD Submit Request message to the ground MME after necessary authentication and policy control.

[0132] The SCEF is a ground network element.

[0133] Step S203, the ground MME determines the satellite ID that can first reach the terminal according to the location information of the terminal and the satellite ID listening list information available for data transmission of the terminal, and estimates the waiting time for the SCS or AS to receive the confirmation message of the downlink data.

[0134] If the ground MME has a data caching function, or the data storage space of the ground MME is sufficient, the following steps S204a-S207a can be continued to be executed; if the ground MME does not have a data caching function, or the data caching space of the ground MME is insufficient, the following steps S204b-S210b can be continued to be executed.

[0135] Step S204a, the ground MME returns a NIDD Submit Reponse message to the SCEF, carrying the estimated waiting time.

[0136] Step S205a, the SCEF forwards the NIDD Submit Reponse message to the SCS / AS.

[0137] Step S206a, the SCS / AS starts a timer.

[0138] The time limit of the timer can be set based on the above-mentioned waiting time.

[0139] Within the time limit of the timer, when the confirmation message of the downlink data is not received, the SCS / AS does not repeatedly send the downlink data to the SCEF, when the timer expires and the confirmation message of the downlink data is not received, the SCS / AS re-sends the downlink data to the SCEF. When the confirmation message of the downlink data is received within the time limit of the timer, the SCS / AS stops the timer.

[0140] Step S207a, the ground MME saves the downlink data.

[0141] Step S204b, the ground MME returns the NIDD Submit Reponse message to the ground SCEF, and carries the cache indication and the estimated waiting time.

[0142] Step S205b, the SCEF saves the downlink data.

[0143] After the SCEF receives the cache indication, the SCEF can save the downlink data.

[0144] Step S206b, the NIDD Submit Reponse message is sent to the SCS / AS, and carries the estimated waiting time.

[0145] Step S207b, after the SCS / AS receives the message, a timer is started.

[0146] For the description of the above steps S206b and S207b, refer to the related description of S204a and S206a, which will not be repeated here.

[0147] Step S208b, when the satellite feeder link of the satellite ID determined by the ground MME is available, the ground MME sends the NIDD Submit Indication message to the SCEF.

[0148] In the NIDD Submit Indication message, it is indicated that the downlink data can be sent.

[0149] Step S209b, the SCEF sends the NIDD Submit Request message containing the downlink data to the ground MME.

[0150] Step S210b, the SCEF deletes the downlink data.

[0151] After the above steps S204a-S207a are executed, the following step S211 can be executed, or after the above steps S204b-S210b are executed, the following step S211 can be executed.

[0152] Step S211, the ground MME sends the downlink data to the on-board MME.

[0153] Step S212, the on-board MME returns the downlink data Acknowledgement (ACK) to the ground MME.

[0154] Step S213, the ground MME deletes the downlink data.

[0155] It should be noted that the step S213 is a step performed when the steps S204a-S207a are performed, that is, the step S213 is for the case that the ground MME has the data buffering function or the data storage space of the ground MME is sufficient.

[0156] The step S213, the on-board MME stores the downlink data and determines the estimated time for the downlink data to reach the terminal according to the location information of the terminal and the ephemeris information.

[0157] The step S214, the on-board MME pages the terminal through the on-board base station (eNodeB) when the terminal is in the coverage of the satellite indicated by the satellite ID and the service link is available.

[0158] The step S215, the on-board MME establishes / resumes the connection with the terminal.

[0159] The establishment / resumption of the connection between the on-board MME and the terminal can mean the establishment or the resumption of the Radio Resource Control (RRC) connection.

[0160] The step S216, the on-board MME sends the stored downlink data to the terminal.

[0161] The step S217, the on-board MME deletes the stored downlink data.

[0162] The step S218, the on-board MME sends the acknowledgement message of the downlink data to the ground MME through the NIDD Submit Response message when the feeder link of the satellite where the on-board MME is located is available.

[0163] The NIDD Submit Response message includes the acknowledgement message of the downlink data.

[0164] The step S219, the ground MME forwards the NIDD Submit Response message to the SCEF.

[0165] The step S220, the ground SCEF forwards the NIDD Submit Response message to the SCS / AS.

[0166] The step S221, the SCS receives the NIDD Submit Response message and stops the timer.

[0167] If the SCS receives the NIDD Submit Response message carrying the acknowledgement message of the downlink data within the time limit of the timer, the timer can be stopped.

[0168] The non-IP type downlink data transmission method provided in the above embodiments can determine a satellite used for downlink transmission based on satellite identification listening list information in a multi-satellite scenario, thereby realizing downlink transmission in a single-satellite or multi-satellite scenario. Load balancing of different store-and-forward satellites and terminal energy saving purposes can be realized.

[0169] (2) IP type downlink data transmission method.

[0170] In some embodiments, the ground MME can also receive a downlink data notification sent by the SGW, and the downlink data notification is used to indicate that downlink data needs to be sent. The ground MME can send a downlink data notification confirmation message to the SGW.

[0171] In some embodiments, when the ground MME does not have a data storage function, or the storage space is insufficient to store the downlink data, the downlink data notification confirmation message sent to the SGW can include a storage indication; wherein the storage indication is used to indicate storage of the downlink data.

[0172] That is, when the ground MME does not have a data storage function, or the storage space is insufficient to store the downlink data, the ground MME can use the storage indication to let the SGW store the downlink data.

[0173] In some embodiments, for the case that the ground MME uses the storage indication to let the SGW store the downlink data, when the satellite feeder link corresponding to the first satellite identification is available, the ground MME can obtain the downlink data from the SGW and send the downlink data to the first satellite MME.

[0174] In some embodiments, when the satellite feeder link corresponding to the first satellite identification is not available, the ground MME can receive the downlink data sent by the SGW and save the downlink data, and then when the satellite feeder link corresponding to the first satellite identification is available, send the downlink data to the first satellite MME corresponding to the first satellite identification.

[0175] In some embodiments, for the case that the ground MME saves the downlink data, after sending the downlink data to the first satellite MME corresponding to the first satellite identification, the ground MME can delete the downlink data.

[0176] For example, FIG. 3 is a flowchart of an IP type downlink data transmission method, as shown in FIG. 3, the method includes but is not limited to the following steps:

[0177] Step S300, the SGW receives the downlink data sent by the PGW.

[0178] It should be noted that before performing the above step S300, steps S101 to S105 shown in FIG. 2 can also be performed.

[0179] Step S301, the ground MME receives the downlink data notification from the SGW.

[0180] If the ground MME has a data buffering function, or the data storage space of the ground MME is sufficient, the following steps S302a-S306a can be executed; if the ground MME does not have a data buffering function, or the data buffering space of the ground MME is insufficient, the following steps S304b-S307b can be executed.

[0181] The downlink data notification is used to notify the ground network element that there is downlink data to be transmitted.

[0182] Step S302a, the ground MME sends a downlink data notification ACK to the SGW.

[0183] Step S303a, the ground MME acquires the downlink data from the SGW and saves the downlink data.

[0184] The ground MME can update the bearer channel, i.e., update the bearer channel between the ground MME and the SGW, and receive the downlink data sent by the SGW.

[0185] When the ground MME has a data buffering function, or the data storage space of the ground MME is sufficient, the ground network element MME acquires the downlink data from the SGW and saves the downlink data.

[0186] Step S304a, the ground MME determines the satellite ID that can reach the terminal next in the shortest time according to the location information of the terminal, the satellite ID listening list information available for data transmission of the terminal, and the ephemeris information.

[0187] Step S305a, when the feeder link of the satellite corresponding to the satellite ID is available, the ground MME sends the downlink data to the on-board MME corresponding to the satellite ID.

[0188] Step S306a, the ground MME deletes the downlink data.

[0189] After the above step S306a is executed, step S308 can be executed.

[0190] Step S302b, the ground MME determines the satellite ID that can reach the terminal next in the shortest time according to the location information of the terminal, the satellite ID listening list information available for data transmission of the terminal, and the ephemeris information, and estimates the storage time of the downlink data in the SGW.

[0191] Step S303b, the ground MME sends a downlink data notification ACK to the SGW, carrying a storage indication.

[0192] Step S304b, the SGW saves the downlink data.

[0193] Step S305b, the ground MME obtains the downlink data of the UE from the SGW when the satellite feeder link of the satellite ID is available.

[0194] The ground MME can update the bearer channel and receive the downlink data sent by the SGW when the satellite feeder link of the satellite ID is available.

[0195] Step S306b, the SGW deletes the buffered downlink data.

[0196] Step S307b, the ground MME sends the downlink data to the on-board MME corresponding to the satellite ID.

[0197] Step S308, the on-board MME saves the downlink data.

[0198] Step S309, the terminal is paged by the on-board base station when the terminal is in the coverage of the satellite indicated by the satellite ID and the service link is available.

[0199] Step S310, the on-board MME establishes a connection with the terminal.

[0200] Step S311, the on-board MME sends the saved downlink data to the terminal through a NAS message.

[0201] Step S312, the on-board MME deletes the saved downlink data.

[0202] After receiving the non-access layer delivery notification (NAS Delivery Notification) message sent by the on-board base station, the on-board MME knows that the downlink data has been successfully sent to the terminal, and can delete the saved downlink data at this time.

[0203] Further, the on-board MME can forward the NAS Delivery Notification message to the ground MME to inform the MME that the downlink data has been successfully sent to the terminal when the satellite feeder link corresponding to the satellite ID is available.

[0204] The above embodiment provides an IP type downlink data transmission method, which can determine the satellite used for downlink transmission based on the satellite identification monitoring list information in a multi-satellite scenario, so as to realize downlink transmission in a single-satellite or multi-satellite scenario. Load balancing of different store-and-forward satellites and terminal energy saving purposes can be achieved.

[0205] For example, FIG. 4 is a flowchart of an uplink data transmission method provided by an embodiment of the application. The method can include but is not limited to the following steps:

[0206] S41, when the terminal determines that there is uplink data to be transmitted, the terminal listens to the SIB message, and the SIB message includes the second satellite identifier.

[0207] S42, when the terminal available for data transmission satellite identifier listening list information includes the second satellite identifier, the terminal sends the uplink data to the second satellite identifier corresponding to the second satellite MME.

[0208] Wherein, when the terminal available for data transmission satellite identifier listening list information includes the second satellite identifier, the terminal can establish a connection with the second satellite MME, and send the uplink data to the second satellite identifier corresponding to the second satellite MME.

[0209] In some embodiments, the terminal can also send the indication information to the second satellite corresponding to the second satellite identifier, and the indication information is used to indicate that there is downlink data transmission after the uplink data transmission. Wherein, the terminal sending the indication information to the second satellite can mean sending the indication information to the satellite base station on the second satellite, and then sending it to the satellite MME on the second satellite, that is, the second satellite MME mentioned above.

[0210] In some embodiments, the terminal can also receive the arrival time of the downlink data sent by the second satellite MME of the second satellite, and start a second timer, wherein the time limit of the second timer is set based on the arrival time of the downlink data.

[0211] In some embodiments, when the second timer expires and the service link is available, the paging message is listened to, and the downlink data is prepared to be received.

[0212] S43, the second satellite MME saves the uplink data.

[0213] S44, when the satellite feeder link corresponding to the second satellite MME is available, the second satellite MME sends the uplink data to the ground MME.

[0214] In some embodiments, after the second satellite MME sends the uplink data to the ground MME, the second satellite MME can delete the uplink data.

[0215] In some embodiments, the second satellite MME can receive the indication information sent by the terminal, and the indication information is used to indicate that there is downlink data transmission after the uplink data transmission; the second satellite MME can determine the arrival time of the downlink data according to the position information and ephemeris information of the terminal, and send the arrival time of the downlink data to the terminal.

[0216] In some embodiments, the second spaceborne MME can receive the downlink data sent by the ground MME and save the downlink data. When the terminal is in the coverage range corresponding to the second spaceborne MME and the service link is available, the terminal is sent a paging message, a connection with the terminal is established, and the terminal is sent the downlink data.

[0217] In the data transmission method, when the terminal determines that there is uplink data to be transmitted, the terminal can acquire the second satellite identifier included in the SIB message by listening to the SIB message. When the second satellite identifier is included in the satellite identifier listening list information available for data transmission of the terminal, the terminal can send the uplink data to the second spaceborne MME corresponding to the second satellite identifier. In this way, in a multi-satellite scenario, the satellite used for uplink transmission can be determined through the SIB message and the satellite identifier listening list information, thereby realizing uplink transmission in a single-satellite or multi-satellite scenario.

[0218] In the uplink data transmission method, non-Internet Protocol (non-IP) type uplink data transmission methods and Internet Protocol (IP) type uplink data transmission methods are involved. To more clearly illustrate the uplink data transmission method in the embodiments of the present application, the non-IP type uplink data transmission method and the IP type uplink data transmission method are described separately.

[0219] For example, FIG. 5 is a flowchart of a non-IP type uplink data transmission method. As shown in FIG. 5, the method includes but is not limited to the following steps:

[0220] S501. When the terminal determines that there is uplink data to be transmitted according to application or user indication information and the service link is available, the terminal receives the SIB message and determines that the satellite ID in the SIB message belongs to the satellite identifier listening list information available for data transmission of the terminal.

[0221] In this embodiment, the terminal is in an Evolved Packet Core Mobility Management Connected State (ECM) idle state.

[0222] S502. The terminal establishes a connection with the spaceborne base station and the spaceborne MME.

[0223] S503. The terminal sends the uplink data to the spaceborne MME through the NAS message.

[0224] S504. The spaceborne MME determines whether the information indicating that there is downlink data transmission after the uplink data transmission is carried in the message.

[0225] The downlink data can be an uplink data receiving acknowledgement message, such as an uplink acknowledgement (UL ACK) or an uplink response (UL response).

[0226] If yes, the on-board MME determines the possible arrival time of the downlink data according to the terminal location information and ephemeris information, executes steps S505, S506 and S507, and executes step S508; if no, steps S505, S506 and S507 are not executed, and step S508 is executed.

[0227] S505, the on-board MME informs the terminal of the arrival time of the downlink data through a NAS message.

[0228] S506, the terminal starts a timer.

[0229] The period of the timer is set according to the arrival time of the downlink data.

[0230] S507, when the timer expires and the service link is available, actively listens to the paging and prepares to receive the downlink data.

[0231] S508, the on-board MME saves the uplink data.

[0232] S509, the on-board base station detects no further link message, and releases the RRC connection and the S1-MME connection, respectively.

[0233] The release of the RRC connection and the S1-MME connection can be the release of the RRC connection between the on-board base station and the terminal, and the release of the S1-MME connection between the on-board base station and the on-board MME.

[0234] S510, when the satellite feeder link of the satellite is available, the on-board MME forwards the uplink data to the ground MME.

[0235] S511, the ground MME returns an uplink data receiving ACK message to the on-board MME.

[0236] S512, the on-board MME deletes the saved uplink data.

[0237] After the on-board MME receives the uplink data receiving ACK message, it can know that the uplink data has been successfully transmitted, and can delete the saved uplink data at this time.

[0238] S513, the ground MME sends a NIDD Submit Request containing the uplink data to the ground network element SCEF.

[0239] S514, the SCEF sends a NIDD Submit Indication message containing the uplink data to the SCS / AS.

[0240] S515, the SCS / AS sends a NIDD Submit Response message to the ground network element SCEF to confirm the receipt of the uplink data.

[0241] S516, the SCEF forwards the NIDD Submit Response message to the ground MME to confirm the receipt of the uplink data.

[0242] The above-mentioned non-IP type uplink data transmission method can determine the satellite used for uplink transmission through SIB message and satellite identification monitoring list information in a multi-satellite scenario, thereby realizing uplink transmission in a single-satellite or multi-satellite scenario. Load balancing of different store-and-forward satellites and terminal energy saving purposes can be achieved.

[0243] For example, FIG. 6 is a flowchart of an IP type uplink data transmission method. As shown in FIG. 6, the method can include steps S501 to S510 as shown in FIG. 5, and after step S501, can further include but not limited to the following steps:

[0244] S601, the on-board MME deletes the saved uplink data.

[0245] S602, the ground MME updates the bearer channel.

[0246] S603, the ground MME sends the uplink data to the SGW.

[0247] S604, the SGW forwards the uplink data to the PGW.

[0248] The PGW can forward the uplink data to the SCS / AS.

[0249] The above-mentioned IP type uplink data transmission method can determine the satellite used for uplink transmission through SIB message and satellite identification monitoring list information in a multi-satellite scenario, thereby realizing uplink transmission in a single-satellite or multi-satellite scenario. Load balancing of different store-and-forward satellites and terminal energy saving purposes can be achieved.

[0250] It should be understood that although the steps in the flowcharts involved in the above embodiments are shown in sequence according to the arrows, the steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified herein, the execution of the steps is not strictly limited in sequence, and the steps can be executed in other orders. Moreover, at least some of the steps in the flowcharts involved in the above embodiments can include multiple steps or multiple stages, which are not necessarily executed at the same time, but can be executed at different times, and the execution order of the steps or stages is not necessarily sequential, but can be alternately or alternately executed with at least part of other steps or steps or stages in other steps.

[0251] Based on the same technical concept, the embodiments of the present application also provide a communication device. The communication device can implement the functions of one or more of the MME, the SCEF, the SGW, the SCS, the AS, the terminal, and the second on-board MME in the foregoing embodiments.

[0252] For example, FIG. 7 is a structural schematic diagram of a communication device provided by an embodiment. The communication device includes a memory 701, a transceiver 702, and a processor 703, wherein the memory 701, the transceiver 702, and the processor 703 are connected through a bus interface.

[0253] The memory 701 is configured to store a computer program; and the transceiver 702 is configured to transceive data under the control of the processor 703.

[0254] For the case that the communication device is a ground MME:

[0255] The processor 703 is configured to read the computer program in the memory 701 and perform the following operations:

[0256] According to the satellite identifier monitoring list information available for data transmission of the terminal, determine a first satellite identifier that is the first reachable satellite identifier for the terminal;

[0257] When the satellite feeder link corresponding to the first satellite identifier is available, send downlink data to a first on-board MME corresponding to the first satellite identifier.

[0258] In some embodiments, the processor 703 is further configured to read the computer program in the memory 701 and perform the following operations:

[0259] Receive the downlink data sent by the SCEF through the SCS or the AS;

[0260] Determine the waiting time for the SCS or the AS to receive an acknowledgement message for the downlink data;

[0261] sending, by the SCEF, the latency to the SCS or AS.

[0262] In some embodiments, the processor 703 is further configured to read the computer program in the memory 701 and perform the following operations:

[0263] When the satellite feeder link corresponding to the first satellite identity is unavailable, the downlink data is saved before the first satellite identity corresponding on-board MME is sent to the downlink data.

[0264] In some embodiments, the processor 703 is further configured to read the computer program in the memory 701 and perform the following operations:

[0265] When the ground MME does not have a data storage function, or the storage space is insufficient to store the downlink data, a storage indication is sent to the SCEF, and the storage indication is used to indicate that the downlink data is stored.

[0266] In some embodiments, the processor 703 is specifically configured to read the computer program in the memory 701 and perform the following operations:

[0267] When the satellite feeder link corresponding to the first satellite identity is available, a downlink data sending indication is sent to the SCEF.

[0268] The downlink data sent by the SCEF is received, and the downlink data is sent to the first on-board MME.

[0269] In some embodiments, the processor 703 is further configured to read the computer program in the memory 701 and perform the following operations:

[0270] A downlink data notification sent by the SGW is received, and the downlink data notification is used to indicate that downlink data sending needs to be performed.

[0271] A downlink data notification confirmation message is sent to the SGW.

[0272] In some embodiments, the processor 703 is further configured to read the computer program in the memory 701 and perform the following operations:

[0273] When the ground MME does not have a data storage function, or the storage space is insufficient to store the downlink data, the downlink data notification confirmation message includes a storage indication.

[0274] The storage indication is used to indicate that the downlink data is stored.

[0275] In some embodiments, the processor 703 described above is specifically configured to read a computer program in the memory 701 and perform the following operations:

[0276] When the satellite identified by the first satellite identifier is available, the SGW is acquired to obtain the downlink data, and the first satellite on-board MME is sent to the downlink data.

[0277] In some embodiments, the processor 703 described above is also configured to read a computer program in the memory 701 and perform the following operations:

[0278] Before the first satellite on-board MME corresponding to the first satellite identifier is sent downlink data, when the satellite corresponding to the first satellite identifier is not available, the downlink data sent by the SGW is received, and the downlink data is saved.

[0279] In some embodiments, the processor 703 described above is also configured to read a computer program in the memory 701 and perform the following operations:

[0280] After the first satellite on-board MME corresponding to the first satellite identifier is sent downlink data, the downlink data is deleted.

[0281] In some embodiments, the processor 703 described above is also configured to read a computer program in the memory 701 and perform the following operations:

[0282] According to the first information, the satellite identifier monitoring list information available for data transmission of the terminal is determined;

[0283] The first information includes at least one of the following:

[0284] The subscription data of the terminal, the satellite ephemeris information, the location information of the terminal, and the MME default configuration information.

[0285] In some embodiments, the processor 703 described above is also configured to read a computer program in the memory 701 and perform the following operations:

[0286] The satellite identifier monitoring list information available for data transmission of the terminal is sent to the terminal;

[0287] And / or,

[0288] The context information of the terminal is sent to the satellite on-board MME corresponding to the range indicated by the satellite identifier monitoring list information.

[0289] In some embodiments, the processor 703 described above is specifically configured to read a computer program in the memory 701 and perform the following operations:

[0290] determine a first satellite identity that is next to reach the terminal according to location information of the terminal and satellite identity monitoring list information available to the terminal for data transmission.

[0291] For the case that the communication device is an SCEF or an SGW:

[0292] The processor 703 is specifically configured to read the computer program in the memory 701 and perform the following operations:

[0293] receive a storage instruction sent by a ground MME and store downlink data, wherein the storage instruction is used to instruct to store the downlink data;

[0294] send the downlink data to the ground MME.

[0295] In some embodiments, for the case that the communication device is an SCEF, the processor 703 is further configured to read the computer program in the memory 701 and perform the following operations:

[0296] receive the downlink data sent by an SCS or an AS;

[0297] send the downlink data to the ground MME;

[0298] receive a waiting time of an acknowledgement message of the downlink data sent by the ground MME, and send the waiting time to the SCS or the AS.

[0299] In some embodiments, for the case that the communication device is an SGW, the processor 703 is further configured to read the computer program in the memory 701 and perform the following operations:

[0300] send a downlink data notification to the ground MME, wherein the downlink data notification is used to instruct to perform downlink data sending;

[0301] The processor 703 is specifically configured to read the computer program in the memory 701 and perform the following operations:

[0302] receive a downlink data notification acknowledgement message sent by the ground MME, wherein the downlink data notification acknowledgement message comprises the storage instruction.

[0303] In some embodiments, the processor 703 is further configured to read the computer program in the memory 701 and perform the following operations:

[0304] after the downlink data is sent to the ground MME, delete the downlink data.

[0305] For the case that the communication device is an SCS or an AS:

[0306] The processor 703 is configured to read a computer program in the memory 701 and perform the following operations:

[0307] sending downlink data to an SCEF or an SGW;

[0308] receiving a waiting time of an acknowledgement message for the downlink data sent by the SCEF or the SGW;

[0309] starting a first timer, wherein a time limit of the first timer is set based on the waiting time.

[0310] In some embodiments, the processor 703 is further configured to read a computer program in the memory 701 and perform the following operations:

[0311] when the first timer expires and the acknowledgement message is not received, resending the downlink data to the SCEF or the SGW;

[0312] when the acknowledgement message is received within the time limit of the first timer, canceling the first timer.

[0313] For the case that the communication device is a terminal:

[0314] The processor 703 is configured to read a computer program in the memory 701 and perform the following operations:

[0315] when it is determined that there is uplink data to be transmitted, listening to a SIB message, wherein the SIB message includes a second satellite identifier;

[0316] when the second satellite identifier is included in satellite identifier listening list information of the terminal available for data transmission, sending the uplink data to a second satellite MME corresponding to the second satellite identifier.

[0317] In some embodiments, the processor 703 is further configured to read a computer program in the memory 701 and perform the following operations:

[0318] sending indication information to the second satellite corresponding to the second satellite identifier, wherein the indication information is used to indicate that there is downlink data transmission after the uplink data transmission;

[0319] receiving an arrival time of downlink data sent by a second satellite MME of the second satellite;

[0320] starting a second timer, wherein a time limit of the second timer is set based on the arrival time of the downlink data.

[0321] In some embodiments, the processor 703 is further configured to read a computer program in the memory 701 and perform the following operations:

[0322] When the second timer expires and a service link is available, listen for a paging message, and prepare to receive the downlink data.

[0323] For the case where the communication device is a second on-board MME:

[0324] The processor 703 is configured to read a computer program in the memory 701 and perform the following operations:

[0325] Receive uplink data sent by a terminal, and save the uplink data;

[0326] When a satellite feeder link corresponding to the second on-board MME is available, send the uplink data to a ground MME.

[0327] In some embodiments, the processor 703 is further configured to read a computer program in the memory 701 and perform the following operations:

[0328] After sending the uplink data to the ground MME, delete the uplink data.

[0329] In some embodiments, the processor 703 is further configured to read a computer program in the memory 701 and perform the following operations:

[0330] Receive indication information sent by a terminal, the indication information being used to indicate that there is downlink data transmission after the uplink data transmission;

[0331] According to position information and ephemeris information of the terminal, determine an arrival time of the downlink data;

[0332] Send the arrival time of the downlink data to the terminal.

[0333] In some embodiments, the processor 703 is further configured to read a computer program in the memory 701 and perform the following operations:

[0334] Receive the downlink data sent by the ground MME, and save the downlink data;

[0335] When a service link is available and the terminal is in a coverage range corresponding to the second on-board MME, send a paging message to the terminal, establish a connection with the terminal, and send the downlink data to the terminal.

[0336] In one exemplary embodiment, as shown in FIG. 8, a structural block diagram of a ground MME includes:

[0337] The determining module 801 is configured to determine a first satellite identifier that is the first to reach the terminal according to satellite identifier monitoring list information available to the terminal for data transmission.

[0338] The sending module 802 is configured to send, when a satellite feeder link corresponding to the first satellite identifier is available, downlink data to a first on-satellite MME corresponding to the first satellite identifier.

[0339] In some embodiments, the ground MME further includes a receiving module 803.

[0340] The receiving module 803 is configured to receive the downlink data sent by the SCEF through the SCS or the AS.

[0341] The determining module 801 is further configured to determine a waiting time for the SCS or the AS to receive an acknowledgement message for the downlink data.

[0342] The sending module 802 is further configured to send the waiting time to the SCS or the AS through the SCEF.

[0343] In some embodiments, the ground MME further includes a saving module 804 configured to save the downlink data when the satellite feeder link corresponding to the first satellite identifier is unavailable.

[0344] In some embodiments, the sending module 802 is further configured to send, when the ground MME does not have a data storage function or the storage space is insufficient to store the downlink data, a storage indication to the SCEF, where the storage indication is used to indicate storage of the downlink data.

[0345] In some embodiments, the sending module 802 is specifically configured to:

[0346] The sending, when the satellite feeder link corresponding to the first satellite identifier is available, of the downlink data to the first on-satellite MME corresponding to the first satellite identifier includes:

[0347] sending, when the satellite feeder link corresponding to the first satellite identifier is available, a downlink data sending indication to the SCEF;

[0348] receiving the downlink data sent by the SCEF and sending the downlink data to the first on-satellite MME.

[0349] In some embodiments, the receiving module 803 is further configured to receive a downlink data notification sent by a SGW, where the downlink data notification is used to indicate that downlink data sending is required.

[0350] The sending module 802 is further configured to send a downlink data notification acknowledgement message to the SGW.

[0351] In some embodiments, the downlink data notification acknowledgement message comprises a storage indication when the ground MME does not have a data storage function, or the storage space is insufficient to store the downlink data.

[0352] The storage indication is used to indicate storage of the downlink data.

[0353] In some embodiments, the sending module 802 is specifically configured to:

[0354] The sending of the downlink data to the first satellite-identified corresponding first on-satellite MME when the satellite feeder link corresponding to the first satellite identification is available comprises:

[0355] When the satellite feeder link corresponding to the first satellite identification is available, the downlink data is acquired from the SGW, and the downlink data is sent to the first on-satellite MME.

[0356] In some embodiments, the receiving module 803 is further configured to, when the satellite feeder link corresponding to the first satellite identification is unavailable, receive the downlink data sent by the SGW and save the downlink data before the sending module 802 sends the downlink data to the first satellite-identified corresponding first on-satellite MME.

[0357] In some embodiments, the ground MME further comprises a deleting module 805 configured to delete the downlink data after the sending module 802 sends the downlink data to the first satellite-identified corresponding first on-satellite MME.

[0358] In some embodiments, the determining module 801 is further configured to determine, according to first information, satellite identification monitoring list information available for data transmission of the terminal;

[0359] The first information comprises at least one of the following:

[0360] Subscription data of the terminal, satellite ephemeris information, location information of the terminal, and MME default configuration information.

[0361] In an exemplary embodiment, as shown in FIG. 9, a structure block diagram of an SCEF or SGW comprises:

[0362] The receiving module 901 is configured to receive a storage indication sent by a ground MME and store downlink data, wherein the storage indication is used to indicate storage of the downlink data.

[0363] The sending module 902 is configured to send the downlink data to the ground MME.

[0364] In some embodiments, the receiving module 901, applied to the SCEF, is further configured to receive the downlink data sent by the SCS or the AS; the sending module 902 is further configured to send the downlink data to the ground MME; the receiving module 901 is further configured to receive a waiting time of an acknowledgement message for the downlink data sent by the ground MME, and the sending module 902 is further configured to send the waiting time to the SCS or the AS.

[0365] In some embodiments, the sending module 902, applied to the SGW, is further configured to send a downlink data notification to the ground MME, the downlink data notification being used to indicate that downlink data sending needs to be performed.

[0366] The receiving module 901 is specifically configured to receive a downlink data notification acknowledgement message sent by the ground MME, and the storage indication is included in the downlink data notification acknowledgement message.

[0367] In some embodiments, the SCEF or the SGW further comprises a deleting module 903, configured to delete the downlink data after the sending module 902 sends the downlink data to the ground MME.

[0368] In one exemplary embodiment, as shown in FIG. 10, a structural block diagram of an SCS or an AS comprises:

[0369] The sending module 1001 is configured to send downlink data to an SCEF or an SGW.

[0370] The receiving module 1002 is configured to receive a waiting time of an acknowledgement message for the downlink data sent by the SCEF or the SGW.

[0371] The timing module 1003 is configured to start a first timer, and a time limit of the first timer is set based on the waiting time.

[0372] In some embodiments, the sending module 1001 is further configured to resend the downlink data to the SCEF or the SGW when the first timer expires and the acknowledgement message is not received.

[0373] The timing module 1003 is further configured to cancel the first timer when the acknowledgement message is received within the time limit of the first timer.

[0374] In one exemplary embodiment, as shown in FIG. 11, a structural block diagram of a terminal comprises:

[0375] The receiving module 1101 is configured to receive a SIB message, and the second satellite identifier is included in the SIB message.

[0376] The sending module 1102 is configured to send uplink data to a second satellite corresponding to a second satellite identity when the terminal is available for data transmission and the second satellite identity is included in the satellite identity monitoring list information.

[0377] In some embodiments, the sending module 1102 is further configured to send indication information to the second satellite corresponding to the second satellite identity, where the indication information is used to indicate that there is downlink data transmission after the uplink data transmission.

[0378] The receiving module 1101 is further configured to receive an arrival time of downlink data sent by a second satellite MME of the second satellite.

[0379] The terminal further includes a timing module 1103 configured to start a second timer, where a time limit of the second timer is set based on the arrival time of the downlink data.

[0380] In some embodiments, the terminal further includes a monitoring module 1104 configured to monitor a paging message when the second timer expires and a service link is available, and prepare to receive the downlink data.

[0381] In one exemplary embodiment, as shown in FIG. 12, a structural block diagram of a second satellite MME includes:

[0382] The receiving module 1201 is configured to receive uplink data sent by a terminal and save the uplink data.

[0383] The sending module 1202 is configured to send the uplink data to a ground MME when a satellite feeder link corresponding to the second satellite MME is available.

[0384] In some embodiments, the second satellite MME further includes a deletion module 1203 configured to delete the uplink data after the sending module 1202 sends the uplink data to the ground MME.

[0385] In some embodiments, the receiving module 1201 is further configured to receive indication information sent by the terminal, where the indication information is used to indicate that there is downlink data transmission after the uplink data transmission.

[0386] The second satellite MME further includes a determination module configured to determine an arrival time of the downlink data based on position information and ephemeris information of the terminal.

[0387] The sending module 1202 is further configured to send the arrival time of the downlink data to the terminal.

[0388] In some embodiments, the second satellite MME further includes the receiving module 1201, which is further configured to receive the downlink data sent by the ground MME and save the downlink data.

[0389] The sending module 1202 is further configured to send a paging message to the terminal, establish a connection with the terminal, and send the downlink data to the terminal when a service link is available and the terminal is in a coverage range corresponding to the MME on the second satellite.

[0390] It should be noted that the division of the modules in the embodiments of the present application is illustrative, and is merely a logical function division. In actual implementation, another division manner can be used. In addition, each functional module in each embodiment of the present application can be integrated in one processing module, or each module can be physically present alone, or two or more modules can be integrated in one module. The integrated module can be realized in the form of hardware or in the form of a software functional module.

[0391] When the integrated module is realized in the form of a software functional module and sold or used as an independent product, the integrated module can be stored in a processor-readable storage medium. Based on this understanding, the technical solutions of the present application, essentially or the part that contributes to the prior art, or all or part of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium, and includes several instructions to cause a computer device (which can be a personal computer, a server, or a network device, etc.) or a processor to perform all or part of the steps of the methods described in the various embodiments of the present application.

[0392] It should be noted that the above-described apparatus provided by the embodiments of the present application can implement all the method steps achieved by the method embodiments and achieve the same technical effects. Therefore, the same parts and beneficial effects of the method embodiments are not described in detail.

[0393] In one embodiment, a computer-readable storage medium is provided, which stores a computer program. The computer program is executed by a processor to implement all the method steps achieved by the above method embodiments.

[0394] In one embodiment, a computer program product is provided, which includes a computer program. The computer program is executed by a processor to implement all the method steps achieved by the above method embodiments.

[0395] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a non-volatile computer readable storage medium, and when the computer program is executed, the processes of the above-mentioned embodiments of the methods can be included. Any reference to memory, database or other medium used in the embodiments provided in the present application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (Read-Only Memory, ROM), magnetic tape, floppy disk, flash memory, optical storage, high-density embedded non-volatile memory, resistive memory (ReRAM), magnetoresistive memory (Magnetoresistive Random Access Memory, MRAM), ferroelectric memory (Ferroelectric Random Access Memory, FRAM), phase change memory (Phase Change Memory, PCM), graphene memory, etc. Volatile memory can include random access memory (Random Access Memory, RAM) or external cache memory, etc. As an illustration but not limitation, the RAM can be in various forms, such as static random access memory (Static Random Access Memory, SRAM) or dynamic random access memory (Dynamic Random Access Memory, DRAM), etc. The database involved in the embodiments provided in the present application can include at least one of a relational database and a non-relational database. The non-relational database can include a distributed database based on a block chain, etc., without being limited thereto. The processor involved in the embodiments provided in the present application can be a general-purpose processor, a central processing unit, a graphics processing unit, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, etc., without being limited thereto.

[0396] Any combination of the technical features of the above embodiments can be made. In order to make the description simple, all possible combinations of the technical features in the above embodiments are not described, however, as long as the combination of the technical features does not exist contradictory, it should be considered as the scope of the present application.

[0397] The above embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent of the present application. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of protection of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.

Claims

1. A data transmission method applied to a ground MME, the method comprising: determining a first satellite identity that is the first to reach a terminal according to satellite identity monitoring list information available to the terminal for data transmission; sending downlink data to a first on-board MME corresponding to the first satellite identity when a satellite feeder link corresponding to the first satellite identity is available. 2.The method of claim 1, further comprising: receiving the downlink data sent by an SCEF through an SCS or an AS; determining a waiting time for the SCS or the AS to receive an acknowledgement message for the downlink data; sending the waiting time to the SCS or the AS through the SCEF.

3. The method of claim 2, further comprising: before the sending of the downlink data to the first on-board MME corresponding to the first satellite identity, when the satellite feeder link corresponding to the first satellite identity is not available, saving the downlink data. 4.The method of claim 2, further comprising: when the ground MME does not have a data storage function, or, a storage space is insufficient to store the downlink data, sending a storage indication to the SCEF, the storage indication being used to indicate storage of the downlink data.

5. The method of claim 4, wherein, the sending of the downlink data to the first on-board MME corresponding to the first satellite identity when the satellite feeder link corresponding to the first satellite identity is available, comprising: sending a downlink data sending indication to the SCEF when the satellite feeder link corresponding to the first satellite identity is available; receiving the downlink data sent by the SCEF and sending the downlink data to the first on-board MME. 6.The method of claim 1, further comprising: receiving a downlink data notification sent by an SGW, the downlink data notification being used to indicate that downlink data sending needs to be performed; sending a downlink data notification acknowledgement message to the SGW. 7.The method of claim 1, wherein, when the ground MME does not have a data storage function, or, a storage space is insufficient to store the downlink data, the downlink data notification acknowledgement message includes a storage indication; wherein the storage indication is used to indicate storage of the downlink data.

8. The method of claim 7, wherein, the sending of the downlink data to the first on-board MME corresponding to the first satellite identity when the satellite feeder link corresponding to the first satellite identity is available, comprising: when the satellite feeder link corresponding to the first satellite identity is available, obtaining the downlink data from an SGW and sending the downlink data to the first on-board MME.

9. The method of claim 6, wherein, before the sending of the downlink data to the first on-board MME corresponding to the first satellite identity, the method further comprising: when the satellite feeder link corresponding to the first satellite identity is not available, receiving the downlink data sent by the SGW and saving the downlink data.

10. The method of claim 3 or 9, further comprising: after the sending of the downlink data to the first on-board MME corresponding to the first satellite identity, deleting the downlink data. 11.The method of claim 1, further comprising: determining satellite identity monitoring list information available to the terminal for data transmission according to first information; wherein the first information includes at least one of the following: Subscription data of the terminal, satellite ephemeris information, location information of the terminal, MME default configuration information.

12. The method of claim 11, further comprising: sending, to the terminal, satellite identity monitoring list information available for data transmission of the terminal; and / or, sending, to an on-board MME corresponding to a range indicated by the satellite identity monitoring list information, context information of the terminal.

13. The method of claim 1, wherein, The determining of the first satellite identity that is next available to reach the terminal comprises: determining the first satellite identity that is next available to reach the terminal according to location information of the terminal and the satellite identity monitoring list information available for data transmission of the terminal.

14. The method of claim 2, further comprising, after the SCS or AS receives the waiting time, starting a first timer; setting a time limit of the first timer based on the waiting time.

15. A data transmission method applied to an SCEF or an SGW, the method comprising: receiving a storage instruction sent by a ground MME and storing downlink data, wherein the storage instruction is used to instruct to store the downlink data; and sending the downlink data to the ground MME. When applied to the SCEF, the method further comprises:

16. The method of claim 15, wherein, receiving the downlink data sent by an SCS or an AS; sending the downlink data to the ground MME; receiving a waiting time of an acknowledgement message for the downlink data sent by the ground MME, and sending the waiting time to the SCS or the AS. When applied to the SGW, the method further comprises:

17. The method of claim 15, wherein, sending a downlink data notification to the ground MME, wherein the downlink data notification is used to instruct to send downlink data; receiving a storage instruction sent by the ground MME, comprising: receiving a downlink data notification acknowledgement message sent by the ground MME, wherein the storage instruction is included in the downlink data notification acknowledgement message. After the sending of the downlink data to the ground MME, 18. The method of claim 15, further comprising: deleting the downlink data.

19. A data transmission method applied to an SCS or an AS, the method comprising: sending downlink data to an SCEF or an SGW; receiving a waiting time of an acknowledgement message for the downlink data sent by the SCEF or the SGW; starting a first timer, wherein a time limit of the first timer is set based on the waiting time.

20. The method of claim 19, further comprising: when the first timer expires and the acknowledgement message is not received, resending the downlink data to the SCEF or the SGW; and when the acknowledgement message is received within the time limit of the first timer, canceling the first timer.

21. A data transmission method applied to a terminal, the method comprising: when it is determined that there is uplink data to be transmitted, listening to a SIB message, wherein a second satellite identity is included in the SIB message; and when the second satellite identity is included in satellite identity monitoring list information available for data transmission of the terminal, sending uplink data to a second on-board MME corresponding to the second satellite identity. ​ 22.The method of claim 21, further comprising: sending, to the second satellite, an indication information indicating that there is downlink data transmission after the uplink data transmission; receiving a time of arrival of the downlink data sent by a second on-board MME of the second satellite; starting a second timer, wherein a time limit of the second timer is set based on the time of arrival of the downlink data. 23.The method of claim 22, further comprising: when the second timer expires and a service link is available, listening to a paging message, and preparing to receive the downlink data. 24.A data transmission method applied to a second on-board MME, the method comprising: receiving uplink data sent by a terminal, and saving the uplink data; when a satellite feeder link corresponding to the second on-board MME is available, sending the uplink data to a ground MME.

25. The method of claim 24, further comprising: after the sending of the uplink data to the ground MME, deleting the uplink data. 26.The method of claim 24, further comprising: receiving an indication information sent by the terminal, the indication information indicating that there is downlink data transmission after the uplink data transmission; determining a time of arrival of the downlink data according to position information and ephemeris information of the terminal; and sending the time of arrival of the downlink data to the terminal. 27.The method of claim 26, further comprising: receiving the downlink data sent by the ground MME, and saving the downlink data; when a service link is available and the terminal is in a coverage range corresponding to the second on-board MME, sending a paging message to the terminal, establishing a connection with the terminal, and sending the downlink data to the terminal.

28. A ground MME comprising: a memory, a transceiver, and a processor: the memory is configured to store a computer program; the transceiver is configured to transceive data under control of the processor; the processor is configured to read the computer program in the memory and perform the method of any one of claims 1 to 14.

29. A SCEF or SGW, comprising: a memory, a transceiver, and a processor: the memory is configured to store a computer program; the transceiver is configured to transceive data under control of the processor; the processor is configured to read the computer program in the memory and perform the method of any one of claims 15 to 18.

30. An SCS or AS, comprising: a memory, a transceiver, and a processor: the memory is configured to store a computer program; the transceiver is configured to transceive data under control of the processor; the processor is configured to read the computer program in the memory and perform the method of claim 19 or 20.

31. A terminal comprising: a memory, a transceiver, and a processor: the memory is configured to store a computer program; the transceiver is configured to transceive data under control of the processor; the processor is configured to read the computer program in the memory and perform the method of any one of claims 21 to 23.

32. A second space-borne MME, comprising: a memory, a transceiver, and a processor: the memory is configured to store a computer program; the transceiver is configured to transceive data under control of the processor; the processor is configured to read the computer program in the memory and perform the method of any one of claims 24 to 26. The processor is configured to read a computer program in the memory and perform the method of any one of claims 24-27.

33. A ground MME comprising: a determining module configured to determine a first satellite identity that is first available to reach a terminal according to satellite identity listening list information available to the terminal for data transmission; a sending module configured to send downlink data to a first on-board MME corresponding to the first satellite identity when a satellite feeder link corresponding to the first satellite identity is available.

34. A SCEF or SGW comprising: a receiving module configured to receive a storage instruction sent by a ground MME and store downlink data, wherein the storage instruction is used to instruct to store the downlink data; a sending module configured to send the downlink data to the ground MME.

35. A SCS or AS comprising: a sending module configured to send downlink data to a SCEF or SGW; a receiving module configured to receive a waiting time of an acknowledgement message for the downlink data sent by the SCEF or SGW; a timing module configured to start a first timer, wherein a time limit of the first timer is set based on the waiting time.

36. A terminal comprising: a receiving module configured to receive a SIB message, wherein the SIB message comprises a second satellite identity; a sending module configured to send uplink data to a second satellite corresponding to the second satellite identity when the second satellite identity is included in satellite identity listening list information available to the terminal for data transmission.

37. A second on-board MME comprising: a receiving module configured to receive uplink data sent by a terminal through a second on-board base station and save the uplink data; a sending module configured to send the uplink data to a ground MME when a satellite feeder link corresponding to the second on-board MME is available.

38. A computer readable storage medium storing a computer program, wherein the computer program is executed by a processor to implement the method of any one of claims 1-27.

39. A computer program product comprising a computer program, wherein the computer program is executed by a processor to implement the method of any one of claims 1-27.

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