Satellite communication method and system based on storage and forwarding (SF) operation

Abstract

The invention discloses a method based on storage and forwarding (Samp; the satellite communication method comprises the following steps: receiving a moving track of a mobile terminal uploaded by a low-orbit satellite, position information of a ground gateway station uploaded by the ground gateway station and ephemeris information of the related low-orbit satellite through a high-orbit satellite; in the high-orbit satellites, according to ephemeris information and the positions of the ground gateway stations, the feeder link connection period of each low-orbit satellite and each ground gateway station is calculated; in the high-orbit satellites, screening the low-orbit satellites based on ephemeris information, a movement track and a feeder link connection period to generate Samp; f, a monitoring list of the operation. According to the satellite communication method, guidance Samp is dynamically generated through cooperative networking of high and low orbit satellites; according to the monitoring list operated by F, the mobile terminal only monitors paging messages of low-orbit satellites in the monitoring list, and the ground gateway station directionally sends MT data, so that invalid monitoring and redundant transmission are reduced, the energy consumption of the mobile terminal is reduced, and the satellite bandwidth is saved.

Description

Technical Field

[0001] The present invention relates to the field of satellite communication technology, and in particular to a satellite communication method and system based on store-and-forward (S&F) operation. Background Art

[0002] Store and Forward (S&F) is a phased satellite communication mode designed specifically for delay-tolerant services. Its core processes include:

[0003] Service link phase: The terminal (UE) establishes a connection with the satellite and transmits data. At this time, the satellite is not connected to the ground network, and the data is temporarily stored on the satellite.

[0004] Feeder link phase: When the satellite establishes a connection with the ground gateway station, the cached data is forwarded to the ground network.

[0005] This mode allows maintaining basic communication capabilities during intermittent satellite coverage or feeder link interruptions, and is suitable for non-real-time services such as the Internet of Things and ocean monitoring.

[0006] Existing satellite communication systems supporting S&F generally use static monitoring list pre-configuration, that is: the satellite broadcasts a predefined static satellite ID list (including satellite identifiers supporting S&F operations) to the terminal, and the terminal needs to continuously monitor the broadcast signals of all satellites in the list. However, due to the dynamic changes in satellite coverage (especially for low-earth orbit satellites), the static list cannot reflect the real-time link status, resulting in the terminal monitoring a large number of invalid satellites and a sharp increase in energy consumption.

[0007] There are also solutions through blind monitoring and random access: in the absence of a monitoring list, the terminal needs to scan all available satellite frequency bands to find S&F opportunities. However, the frequent activation of the radio frequency module leads to too high power consumption of the terminal and is prone to missing effective communication windows.

[0008] In addition, there are also solutions where the ground gateway station predicts the availability of the feeder link based on historical ephemeris data and sends S&F operation instructions with a fixed duration to the terminal. However, without combining the terminal's real-time location and the satellite's dynamic coverage range, the prediction error is large, resulting in communication recovery delays or data loss. Summary of the Invention

[0009] The purpose of the present invention is to provide a satellite communication method and system based on store-and-forward (S&F) operation that can dynamically generate S&F operation parameters based on real-time data to solve the deficiencies of the above technical problems.

[0010] To achieve the above object, the present invention provides a satellite communication method based on store-and-forward (S&F) operations for a high-low orbit satellite networking communication system. The communication system includes a geostationary satellite and a plurality of low-earth orbit satellites. The low-earth orbit satellites support S&F operations. Base stations and core network elements are deployed on the low-earth orbit satellites. There are inter-satellite links between the plurality of low-earth orbit satellites, and there is an inter-satellite link between the low-earth orbit satellites and the geostationary satellite. The method includes:

[0011] Receiving, by the geostationary satellite, the movement trajectory of the mobile terminal uploaded by the low-earth orbit satellite, as well as the position information of the ground gateway station uploaded by the ground gateway station and the ephemeris information of the low-earth orbit satellite related to the area where the mobile terminal is currently and will be in a certain period in the future;

[0012] In the geostationary satellite, calculating the feeder link connection period between each low-earth orbit satellite and each ground gateway station according to the ephemeris information and the position of the ground gateway station;

[0013] In the geostationary satellite, screening the low-earth orbit satellites that meet the following condition 1 based on the ephemeris information, the movement trajectory, and the feeder link connection period to generate a monitoring list for S&F operations. The data items of the monitoring list include the low-earth orbit satellite identifier, the corresponding feeder link connection time, and the ground gateway station identifier;

[0014] Condition 1: The service link with the mobile terminal is available within a specific period in the future, and a feeder link connection can be established with at least one ground gateway station within this period;

[0015] Broadcasting the monitoring list to the mobile terminal and the ground gateway station through the geostationary satellite;

[0016] The monitoring list is used to indicate the dynamic operations of the mobile terminal and the ground gateway station during S&F operations.

[0017] Preferably, during S&F operations, the mobile terminal only listens to the paging messages of the low-earth orbit satellites in the monitoring list, and the ground gateway station only sends mobile termination data through the low-earth orbit satellites in the monitoring list.

[0018] Preferably, in the geostationary satellite, the duration of S&F operations is also generated based on the feeder link connection period and broadcast to the mobile terminal and the ground gateway station.

[0019] Preferably, when the duration of S&F operations ends, the mobile terminal sends a registration request to the corresponding low-earth orbit satellite in the monitoring list, and the ground gateway station transmits MT data to the corresponding low-earth orbit satellite to resume real-time communication.

[0020] Preferably, the method for the low-earth orbit satellite to obtain the movement trajectory of the mobile terminal includes:

[0021] Based on the network data analysis function in the core network element, the dynamic position information of the mobile terminal uploaded by the base station is received in real time, and the network data analysis function generates the movement trajectory based on this dynamic position information.

[0022] Preferably, the geostationary satellite generates the monitoring list based on the deployed edge computing server.

[0023] Preferably, the geostationary satellite and the low-earth orbit satellite interact through the user plane function.

[0024] The present invention also provides a satellite communication system based on store-and-forward (S&F) operations, and this communication system performs communication work based on the satellite communication method described above.

[0025] The present invention also provides a satellite communication system, which includes:

[0026] One or more processors;

[0027] A memory;

[0028] And one or more programs, where one or more programs are stored in the memory and are configured to be executed by the one or more processors, and the programs include instructions for executing the satellite communication method described above.

[0029] The present invention also provides a computer-readable storage medium, which includes a computer program, and the computer program can be executed by a processor to complete the satellite communication method described above.

[0030] Compared with the prior art, the satellite communication method provided by the above technical solution of the present invention generates a monitoring list through the joint screening based on the mobile terminal trajectory, the low-earth orbit satellite ephemeris, and the feeder link period, and only selects the low-earth orbit satellites that simultaneously meet the service link availability (covering the mobile terminal) and the feeder link availability (covering the ground gateway station) within a specific future period, avoiding the mobile terminal from listening to invalid satellites; the ground gateway station only needs to send MT data to the satellites in the monitoring list, reducing redundant data transmission. In addition, the complex calculations involving multi-source data fusion are handed over to the geostationary satellite for processing, alleviating the computing power bottleneck of the low-earth orbit satellite; moreover, by using the wide-area coverage ability of the geostationary satellite, the monitoring list is synchronously broadcast to all mobile terminals and ground gateway stations in the whole area, effectively reducing the instruction issuance delay. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a flowchart of the satellite communication method in an embodiment of the present invention.

[0032] Figure 2 This is the signaling flowchart for obtaining the movement trajectory in the embodiments of the present invention. Specific embodiments

[0033] To describe in detail the technical content, structural features, achieved objectives and effects of the present invention, the following will be described in detail in conjunction with the embodiments and with reference to the accompanying drawings.

[0034] This embodiment discloses a satellite communication method based on store-and-forward (S&F) operations for a high-low orbit satellite networking communication system.

[0035] First of all, it should be noted that in satellite communication, the S&F operation is a communication mode designed specifically for delay-tolerant services (such as sensor data reporting, offline message pushing), and it includes two key phases:

[0036] Storage phase: The terminal establishes a connection (service link) with the satellite and uploads data to the satellite. At this time, the satellite is not connected to the ground network (the feeder link is disconnected), and the data is temporarily stored on the satellite.

[0037] Forwarding phase: The satellite restores the connection with the ground network (the feeder link is re-established), and the satellite forwards the stored data to the ground gateway station and finally delivers it to the target server.

[0038] Typical scenarios for satellite communication using the S&F operation are as follows:

[0039] Internet of Things devices in remote areas: When the satellite temporarily flies out of the coverage area of the ground station, the device can still upload data to the satellite, and the data will be forwarded after the satellite flies into the coverage area of the ground station.

[0040] Emergency rescue terminals: At the disaster site without ground network coverage, the terminals send distress messages in batches through the S&F mode.

[0041] Currently, mobile terminals need to continuously monitor all satellite broadcast signals to determine which satellites support the S&F operation.

[0042] Based on this, the satellite communication method in this embodiment dynamically generates an S&F monitoring list through a high-low orbit satellite networking architecture to achieve precise operations between the mobile terminal and the ground gateway station.

[0043] The communication system in this embodiment belongs to a regenerative payload architecture, including a geostationary satellite and several low-earth orbit satellites. The low-earth orbit satellites support the S&F operation. Base stations and core network elements are deployed on the low-earth orbit satellites. There are inter-satellite links between several of the low-earth orbit satellites, and there are inter-satellite links between the low-earth orbit satellites and the geostationary satellite.

[0044] Based on the above communication system with a regenerative payload architecture, as Figure 1, the satellite communication method in this embodiment includes the following steps:

[0045] S1: Receive the movement trajectory of the mobile terminal uploaded by the low-earth orbit satellite, as well as the location information of the ground gateway station and the ephemeris information of the low-earth orbit satellite related to the area where the mobile terminal is currently located and in a future period of time, uploaded by the ground gateway station, through the geostationary satellite;

[0046] S2: In the geostationary satellite, calculate the feeder link connection period between each low-earth orbit satellite and each ground gateway station according to the ephemeris information and the location of the ground gateway station;

[0047] S3: In the geostationary satellite, screen the low-earth orbit satellites that meet Condition 1 based on the ephemeris information, the movement trajectory, and the feeder link connection period to generate a monitoring list for S&F operation. The data items of the monitoring list include the low-earth orbit satellite identifier, the corresponding feeder link connection time, and the ground gateway station identifier;

[0048] Condition 1: The service link with the mobile terminal is available within a specific future time period, and a feeder link connection can be established with at least one of the ground gateway stations within this time period.

[0049] S4: Broadcast the monitoring list to the mobile terminal and the ground gateway station through the geostationary satellite.

[0050] Specifically, the geostationary satellite generates the monitoring list based on the deployed edge computing server.

[0051] The monitoring list is used to indicate the dynamic operations of the mobile terminal and the ground gateway station during the S&F operation. That is, the mobile terminal and the ground gateway station perform actions related to the S&F operation according to the geostationary satellite.

[0052] In the above step S1, the low-earth orbit satellite continuously senses the change in the position of the mobile terminal (such as OTDOA positioning) through the on-board base station to generate a movement trajectory, and uploads the data to the geostationary satellite through the inter-satellite link.

[0053] The ground gateway station injects its own geographical location information and the orbital parameters of the associated low-earth orbit satellite (including orbital altitude, inclination, over-the-horizon time window, etc.) into the geostationary satellite.

[0054] In the above step S2, the high-orbit satellite uses a satellite orbit dynamics model to predict the real-time position and velocity of the low-orbit satellite based on the ephemeris information; and combines the position of the ground gateway station to calculate the visible time window (i.e., the feeder link connection period) between the low-orbit satellite and the ground gateway station. For example: If the orbital inclination of the low-orbit satellite LEO-1 is 55°, and the ground gateway station GW-5 is located at 116° east longitude and 40° north latitude, then the available period of the feeder link between LEO-1 and GW-5 is 13:15-13:30 UTC every day.

[0055] On the other hand, during the S&F operation, the mobile terminal only listens to the paging messages of the low-orbit satellites in the monitoring list, and turns off the radio frequency module during idle time to save power. The ground gateway station only sends mobile termination data through the low-orbit satellites in the monitoring list, and preloads MT data according to the time window of the feeder link connection period in the monitoring list.

[0056] When the feeder link is disconnected (i.e., the S&F operation ends), the mobile terminal immediately initiates registration to the next available low-orbit satellite in the monitoring list, and the ground gateway station stops data transmission.

[0057] For the above satellite communication method, first, a monitoring list is generated through joint screening based on the mobile terminal trajectory, low-orbit satellite ephemeris, and feeder link period, and only the low-orbit satellites that simultaneously meet the service link availability (covering the mobile terminal) and feeder link availability (covering the ground gateway station) within a specific future period are selected, avoiding the mobile terminal from listening to invalid satellites. The ground gateway station only needs to send MT data to the satellites in the monitoring list, reducing redundant data transmission.

[0058] Secondly, the complex calculations involving multi-source data fusion are handed over to the high-orbit satellite for processing, alleviating the computing power bottleneck of the low-orbit satellite; moreover, using the wide-area coverage ability of the high-orbit satellite, the monitoring list is synchronously broadcast to all mobile terminals and ground gateway stations, effectively reducing the instruction issuance delay.

[0059] Furthermore, the monitoring list accurately predicts the feeder connection time window of each low-orbit satellite and each ground gateway station, avoiding data loss caused by satellite-ground link mismatch. During the S&F operation, the ground gateway station preloads MT data according to the time window in the monitoring list, enabling the low-orbit satellite to immediately forward the cached data when the feeder link is restored, and shortening the end-to-end interruption time to less than seconds.

[0060] In addition, the mobile terminal only listens to the low-orbit satellites in the monitoring list, and the ground gateway station only sends data to the low-orbit satellites in the monitoring list. Both parties perform operations based on the same spatio-temporal reference, eliminating the registration conflicts caused by information asynchronization in the traditional scheme (such as the ground gateway station sending MT data to uncovered satellites).

[0061] On the other hand, in the high-orbit satellite, the duration of the S&F operation is also generated based on the feeder link connection period and broadcast to the mobile terminal and the ground gateway station.

[0062] In the S&F operation, the duration refers to the complete time window from the disconnection to the reconnection of the feeder link, that is, the time period during which the mobile terminal maintains the service link connection with the low-orbit satellite, but the low-orbit satellite cannot establish a feeder link with the ground gateway station.

[0063] The high-orbit satellite predicts the disconnection time (T_start) and reconnection time (T_end) of its feeder link based on the ephemeris information of the low-orbit satellite and the position of the ground gateway station; then calculates the time difference ΔT = T_end - T_start as the duration of the S&F operation.

[0064] Then, further, at the end of the duration of the S&F operation, the mobile terminal initiates a registration request to the corresponding low-orbit satellite in the monitoring list, and the ground gateway station transmits MT data to the corresponding low-orbit satellite to restore real-time communication.

[0065] That is, for the terminal side:

[0066] After receiving the duration, the mobile terminal only listens for satellite paging in the monitoring list within the ΔT time window;

[0067] Outside the ΔT window (i.e., during non-S&F operation periods), it resumes full-band listening or enters the sleep mode.

[0068] For the ground gateway station side:

[0069] The ground gateway station predicts the MT data sending time according to the duration and only sends data to the satellite in the monitoring list immediately after ΔT ends.

[0070] For example: If ΔT = 14:00 - 14:15 UTC, the ground gateway station starts MT data transmission at 14:15:00.

[0071] It can be seen that in this embodiment, by clarifying the start and end times of the S&F operation, the mobile terminal can accurately control the activation period of the radio frequency module, turn off unnecessary listening functions outside the ΔT window, and effectively reduce power consumption significantly compared with the traditional continuous listening mode.

[0072] Moreover, the mobile terminal and the ground gateway station perform operations based on the same ΔT, eliminating communication conflicts caused by time errors (such as satellite buffer overflow caused by the ground gateway station sending data too early), and greatly improving the success rate of MT data transmission.

[0073] In addition, the ground gateway station schedules the MT data transmission precisely according to ΔT, avoiding attempts to transmit during periods when the feeder link is unavailable, thus saving satellite backhaul bandwidth.

[0074] On the other hand, the method for the low-earth orbit satellite to obtain the movement trajectory of the mobile terminal includes:

[0075] Based on the network data analysis function (NWDAF) in the core network element, the dynamic position information of the mobile terminal uploaded by the base station is received in real time, and the NWDAF generates the movement trajectory based on this dynamic position information.

[0076] On the other hand, the geostationary satellite and the low-earth orbit satellite interact through the user plane function (UPF).

[0077] Specifically, as Figure 2 , the process for the low-earth orbit satellite to obtain the movement trajectory is as follows:

[0078] 1. The access and mobility management function (AMF) supports the location reporting function. The AMF requests the base station (gNB) to provide the current position information of the mobile terminal (UE), the position information and timestamp of the UE's last residence.

[0079] 2. The gNB can sense the position change of the UE through common positioning technologies, such as cell ID positioning method, OTDOA positioning method, UTDOA positioning method, etc.

[0080] 3. After the gNB detects that the position of the UE has changed, it reports the changed position to the AMF.

[0081] 4. The NWDAF subscribes to the position information of the UE from the AMF.

[0082] 5. The AMF dynamically sends the position report of the UE to the NWDAF, that is, every time the AMF receives the latest position information reported by the gNB, it will send it to the NWDAF.

[0083] 6. The NWDAF analyzes the movement trajectory of the UE based on the position information reported by the AMF multiple times.

[0084] 7. The NWDAF sends the analysis result to the UPF.

[0085] 8. The UPF on the low-earth orbit satellite sends the analysis result to the UPF on the geostationary satellite through the inter-satellite link.

[0086] The present invention also discloses another satellite communication system, which includes one or more processors, a memory, and one or more programs. One or more programs are stored in the memory and are configured to be executed by the one or more processors. The programs include instructions for executing the satellite communication method as described above. The processor may be a general-purpose central processing unit (CPU), a microprocessor, an application specific integrated circuit (ASIC), or one or more integrated circuits, and is used to execute relevant programs to implement the functions required by the modules in the satellite communication system of the embodiments of the present application, or to execute the satellite communication method of the method embodiments of the present application.

[0087] The present invention also discloses a computer-readable storage medium, which includes a computer program. The computer program can be executed by a processor to complete the satellite communication method as described above. The computer-readable storage medium may be any available medium that can be accessed by a computer or a data storage device such as a server or a data center that includes one or more integrated available media. The available medium may be a read-only memory (ROM), a random access memory (RAM), a magnetic medium, such as a floppy disk, a hard disk, a magnetic tape, a magnetic disk, or an optical medium, such as a digital versatile disc (DVD), or a semiconductor medium, such as a solid state disk (SSD), etc.

[0088] The embodiments of the present application also disclose a computer program product or a computer program. The computer program product or the computer program includes computer instructions, and the computer instructions are stored in a computer-readable storage medium. The processor of the electronic device reads the computer instructions from the computer-readable storage medium, and the processor executes the computer instructions, so that the electronic device executes the above satellite communication method.

[0089] The above-disclosed are only the preferred embodiments of the present invention. Of course, the scope of the rights of the present invention cannot be limited thereby. Therefore, equivalent changes made according to the scope of the patent application of the present invention still fall within the scope covered by the present invention.

Claims

1. A satellite communication method based on store and forward (S&F) operation, used in a high and low orbit satellite networking communication system, characterized in that: The communication system includes a high-orbit satellite and several low-orbit satellites, the low-orbit satellite supports S&F operations, a base station and a core network element are deployed on the low-orbit satellite, there are inter-satellite links between the several low-orbit satellites, and there is an inter-satellite link between the low-orbit satellite and the high-orbit satellite, and the method includes: Receiving, through the high-orbit satellite, the movement trajectory of the mobile terminal uploaded by the low-orbit satellite, as well as the location information of the ground gateway uploaded by the ground gateway and the ephemeris information of the low-orbit satellite related to the area where the mobile terminal is currently located and in the future; In the high-orbit satellite, according to the ephemeris information and the position of the ground gateway, a feeder link connection period between each of the low-orbit satellites and each of the ground gateways is calculated; In the high-orbit satellite, the low-orbit satellite that meets the following condition 1 is selected based on the ephemeris information, the moving trajectory, and the feeder link connection period to generate a monitoring list for S&F operation, wherein the data items of the monitoring list include the low-orbit satellite identifier and the corresponding feeder link connection time and ground gateway identifier; Condition 1: a service link with the mobile terminal is available within a specific time period in the future, and a feeder link connection can be established with at least one of the ground gateways within the time period; Broadcasting the monitoring list to the mobile terminal and the ground gateway via a high-orbit satellite; The monitoring list is used to indicate the dynamic operation of the mobile terminal and the ground gateway during the S&F operation.

2. The satellite communication method based on store and forward (S&F) operation according to claim 1, characterized in that: During S&F operation, the mobile terminal only monitors the paging messages of the low-orbit satellites in the monitoring list, and the ground gateway only sends mobile-terminated data through the low-orbit satellites in the monitoring list.

3. The satellite communication method based on store and forward (S&F) operation according to claim 1, characterized in that: In the high-orbit satellite, the duration of the S&F operation is also generated based on the feeder link connection period, and the duration is broadcast to the mobile terminal and the ground gateway.

4. The satellite communication method based on the store and forward (S&F) operation according to claim 3, characterized in that: At the end of the duration of the S&F operation, the mobile terminal initiates a registration request to the corresponding low-orbit satellite in the monitoring list, and the ground gateway transmits MT data to the corresponding low-orbit satellite to resume real-time communication.

5. The satellite communication method based on store and forward (S&F) operation according to claim 1, characterized in that: The method for the low-orbit satellite to obtain the moving trajectory of the mobile terminal includes: Based on the network data analysis function in the core network element, the dynamic location information of the mobile terminal uploaded by the base station is received in real time, and the network data analysis function generates the movement trajectory based on the dynamic location information.

6. The satellite communication method based on store and forward (S&F) operation according to claim 1, characterized in that: The high-orbit satellite generates the monitoring list based on the deployed edge computing server.

7. The satellite communication method based on store and forward (S&F) operation according to claim 1, characterized in that: The high-orbit satellite and the low-orbit satellite interact with each other through a user plane function.

8. A satellite communication system based on store and forward (S&F) operation, characterized in that: The communication system performs communication work based on the satellite communication method according to any one of claims 1 to 7.

9. A satellite communication system, characterized in that: include: one or more processors; Memory; and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, the programs comprising instructions for executing the satellite communication method according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that: The invention comprises a computer program which can be executed by a processor to implement the satellite communication method according to any one of claims 1 to 7.

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