Lightweight inter-satellite routing implementation method and system suitable for VDES constellation

Abstract

The application provides a lightweight inter-satellite routing implementation method and system suitable for a VDES constellation, the method comprising: a satellite pre-storing the topology of the entire constellation; a satellite sending end dividing data to be sent into smaller data packets, and encapsulating each data packet according to an IPv4 or IPv6 protocol; a gateway station specifying a central satellite and broadcasting to the entire constellation; each satellite calculating the shortest path from itself to the central satellite according to the central satellite by using a shortest path algorithm; sending IP data packets to the central satellite according to the calculated path; the central satellite sending data to the gateway station; the gateway station sending data and forwarding rules to the central satellite after processing; and the central satellite sending data to a destination satellite according to the forwarding rules. The application realizes interconnection and intercommunication between VDES satellites, and the protocol of the application is simple and reliable, and is suitable for running in a satellite on-board environment.

Description

Technical Field

[0001] This invention relates to the field of inter-satellite link technology, and more specifically, to a lightweight inter-satellite routing implementation method and system suitable for the VDES constellation. Background Technology

[0002] Since the beginning of the 21st century, ships navigating at sea have primarily relied on the Automatic Identification System (AIS) for management, providing services including maritime traffic safety, maintenance of maritime traffic order, and maritime communication. With the continuous development of maritime shipping and the significant increase in the number of vessels at sea, AIS needs to constantly provide new services. These services include communication, weather, hydrology, navigation aids, nautical charts, navigation control, vessel traffic management, navigation risk warnings, remote vessel maintenance, and search and rescue operations, leading to increasing strain on the communication load of the original AIS system. Against this backdrop, the next-generation maritime communication system (VHF Data Exchange System, VDES) has been proposed. As an upgrade to the AIS system, it incorporates satellite networks as part of the system to address various issues existing in the current system and provide high-quality maritime services to vessels navigating the seas.

[0003] Currently, inter-satellite routing protocols mainly include two types: general protocols and proprietary protocols. General protocols typically use the standard TCP / IP protocol, while proprietary protocols include Iridium communication protocols. The VDES inter-satellite link protocol needs to fully consider the characteristics of frequent communication and small data packets in the VDES system, effectively utilize the limited onboard processing resources, and optimize the satellite-to-ground processing flow. Therefore, it is necessary to design a lightweight inter-satellite link protocol suitable for VDES based on standard protocols.

[0004] Patent document CN113765575A discloses a remote sensing constellation routing algorithm based on inter-satellite links, including the following steps: S1, constructing a Walker constellation satellite remote sensing system and simultaneously establishing inter-satellite links and satellite-to-ground links; S2, generating a primary mesh topology along the latitude and longitude directions of the inter-satellite links constructed based on S1; S3, selecting an area and determining ground data transmission stations within the area that can cover the entire area; S4, constructing a secondary mesh topology based on the remote sensing satellites of S1 and the ground transmission stations of S3, and performing time slicing on the secondary mesh topology; S5, performing routing within each time slice; S6, constructing an undirected graph G = (V, E) on the secondary mesh topology based on S5, where V contains all remote sensing satellite nodes and E contains the edges between each node. However, this patent cannot completely solve the existing technical problems, nor can it meet the needs of this invention. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this invention is to provide a lightweight inter-satellite routing implementation method and system suitable for VDES constellations.

[0006] The lightweight inter-satellite routing implementation method for VDES constellations provided by the present invention includes:

[0007] Step 1: Based on constellation information, develop a mission plan at the gateway station, dividing the future mission time period into n time periods ΔT1, ΔT2, ..., ΔT n ;

[0008] Step 2: Based on the satellite's visibility to the gateway station, from the time period ΔT i It is evident that a satellite S is selected from the satellite group of the gateway station. i As the satellite connecting the gateway stations, it is named the time period ΔT. i The central satellite;

[0009] Step 3: At the gateway station, transmit the central satellite information (ΔT1,S1), (ΔT2,S2), ..., (ΔT) via uplink. n ,S n The information is uploaded to the current central satellite, which then broadcasts it to the entire constellation.

[0010] Step 4: Each satellite in the constellation during time period ΔT i S i Set as the end node;

[0011] Step 5: After receiving the uplink information from the ground, the satellite VDES payload encapsulates it into IP packets and forwards them to the satellite's onboard router. The onboard router replaces the destination IP address of the payload packets with S... n IP address;

[0012] Step 6: Use the shortest path algorithm to complete the route planning, and forward the next hop according to the planning result;

[0013] Step 7: Data is sent to the central satellite S i Then, the central satellite transmits the data to the gateway station via the feeder link;

[0014] Step 8: After data processing at the gateway station, generate uplink data as needed, and attach forwarding rules to the uplink data according to the constellation's operating status to generate uplink messages;

[0015] Step 9: After receiving the uplink message, the satellite forwards the data to the destination satellite according to the predetermined path and forwarding rules;

[0016] Step 10: The onboard router queries its own busy / idle status. When it is busy, it retrieves the data packets to be forwarded and writes them into the storage module. When it is idle, it retrieves the data packets from the storage module one by one, determines whether to forward them based on the source and destination addresses, or replaces the corresponding destination address.

[0017] Preferably, in step 1, the time period ΔT i The description is: ΔT i =[T ia -T m ,T ib -T n ];

[0018] Among them, [T ia ,T ib [T] represents the satellite transit time interval. m and T n These represent the remaining time for entry and exit, respectively, i = 1, 2, ..., n.

[0019] Preferably, in step 2, the selection process of the central satellite is as follows: based on the duration T1 of the satellite passing over the ground station and the overlap time T2 with the previous satellite's passing time, calculate aT1+bT2, where a and b are empirical parameters, and select the satellite with a larger aT1+bT2 passing over in the same time period.

[0020] Preferably, in step 3, the process of the central satellite broadcasting information to the entire constellation is as follows: in the broadcast message, a valid hop count is set, and the valid hop count does not exceed 1 / 3 of the total number of satellites; after receiving the broadcast message, the satellite decrements the valid hop count segment value by 1; if the valid hop count segment value is greater than 0, the message is forwarded to all satellites connected to that satellite except for the source message satellite; if the valid hop count segment value is less than or equal to 0, the message is not forwarded.

[0021] Preferably, in step 8, the forwarding rules include: optimal route calculation, performed by the gateway station based on a specific optimal route; and generating a forwarding path table, the forwarding path table being expressed in the form of: S1→S2→…S k 1,2,…,k represent the satellites on the forwarding path; compliance checks limit the number of times satellites with the same forwarding path appear.

[0022] Preferably, in step 8, the data processing of the gateway station includes data reception and storage, parsing and splicing of data packet formats, and restoring the original information.

[0023] Preferably, in step 9, the data forwarding to the destination includes: S1, S2, ..., S... k After receiving the data, each satellite retrieves its own location in S1→S2→…S kThe system retrieves the location of the satellite and information about the next hop satellite; after successfully forwarding to the next satellite, it sends a forwarding success message to the previous satellite; if the current satellite is the destination satellite, it sends a delivery success message to the previous satellite.

[0024] Preferably, in step 10, if the destination address is the central satellite and the router is located on the current central satellite, then no forwarding is performed; if the destination address is the central satellite corresponding to a previous time, then the destination address is replaced with the current central satellite and forwarded; if the destination address is not the central satellite of any previous time, no replacement is performed, and forwarding is performed according to the shortest path routing plan result.

[0025] Preferably, the constellation is a polar orbit constellation. The constellation topology is stored in a lightweight manner using two matrices A1 and A2, respectively, according to the horizontal and vertical connection relationships. They are represented as follows:

[0026]

[0027] Where A1 is the horizontal connection matrix, representing the horizontal connection relationship of constellations. If there is no connection, it is represented as 0, and if there is a connection, it is represented as 1. A2 is the vertical connection matrix, representing the vertical connection relationship of constellations. If there is no connection, it is represented as 0, and if there is a connection, it is represented as 1.

[0028] The lightweight inter-satellite routing implementation system for VDES constellations provided by the present invention employs the aforementioned lightweight inter-satellite routing implementation method for VDES constellations.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] This invention enables interconnection between VDES satellites by equipping them with inter-satellite links and the VDES inter-satellite link protocol, thus overcoming the deficiency of shore-based VDES in not being able to cover distant ocean areas, expanding the service range of the VDES system, and achieving global coverage of the VDES system. It can better support the various functions of VDES. The protocol of this invention is simple and reliable and is suitable for operation in a satellite-borne environment. Attached Figure Description

[0031] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0032] Figure 1 A flow diagram of onboard processing information for the VDES satellite;

[0033] Figure 2 A schematic diagram of the VDES satellite constellation topology. Detailed Implementation

[0034] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0035] Example

[0036] like Figure 1 As shown, VDES satellites form inter-satellite routes through the interconnection between routing and switching modules. The objects connected by the routing and switching modules include the satellite's integrated electronics, VDES payload, and gateway station. The task of the routing and switching modules is to deliver data to the destination at the lowest possible cost.

[0037] like Figure 2 As shown, in the VDES constellation of this invention, the constellation topology is fixed, and the connection relationships between the satellites are fixed. However, due to their orbital characteristics, the relationship between the satellites and the ground gateway stations is dynamically changing, so the satellites connecting the gateway stations also need to be constantly updated.

[0038] This invention provides a lightweight inter-satellite routing implementation method suitable for VDES constellations, with the following specific steps:

[0039] Step 1: The gateway station formulates a mission plan based on constellation information, dividing the future mission period into several time periods of varying lengths, ΔT1, ΔT2, ... ΔT. n ;

[0040] Step 2: Based on the satellite's visibility to the gateway station, from the time period ΔT i It is evident that a satellite S is selected from the satellite group of the gateway station. i As the satellite connecting the gateway stations, it is named the time period ΔT. i The central satellite;

[0041] Step 3: The gateway station transmits the central satellite information (ΔT1,S1), (ΔT2,S2), ..., (ΔT) via the uplink. n ,S n The information is uploaded to the current central satellite, which then broadcasts it to the entire constellation.

[0042] Step 4: Each satellite in the constellation during the time period ΔT i S i Set as the end node;

[0043] Step 5: After receiving the uplink information from the ground, the satellite VDES payload encapsulates it into IP packets and forwards them to the satellite's onboard router. The onboard router replaces the destination IP address of the payload data packets with S... n IP address;

[0044] Step 6: Use the shortest path algorithm to complete the route planning, and forward the next hop according to the planning result;

[0045] Step 7: Data is sent to the central satellite S i Then, the central satellite transmits the data to the gateway station via the feeder link;

[0046] Step 8: After processing, the gateway station generates uplink data as needed, and attaches the forwarding rules to the front of the uplink data according to the constellation's operating status to generate uplink messages.

[0047] Step 9: After receiving the uplink message, the satellite forwards the data to the destination satellite according to the predetermined path and forwarding rules.

[0048] Step 10: The onboard router queries its own busy / idle status. When busy, it retrieves the data packets to be forwarded and writes them to the storage module. When idle, it retrieves the data packets in the module one by one, determines the type based on the source and destination addresses, and decides whether to forward them. If necessary, it replaces the corresponding destination address.

[0049] In step 1, time slice ΔT i The description of (i = 1, 2, ..., n) is as follows:

[0050] ΔT i =[T ia -T m ,T ib -T n ]

[0051] Among them, [T ia ,T ib [T] represents the satellite transit time interval. m and T n These represent the remaining time for entry and exit, respectively.

[0052] In step 2, the method for selecting the central satellite is as follows: based on the duration T1 of the satellite's transit over the ground station and the overlap time T2 with the transit time of the previous satellite, calculate aT1+bT2, where a and b are empirical parameters, and select the satellite with the larger aT1+bT2.

[0053] In step 3, the central satellite broadcasts this information to the entire constellation, which includes the following steps:

[0054] Step 3.1: In the broadcast message, set the number of valid hops, which shall not exceed 1 / 3 of the total number of satellites;

[0055] Step 3.2: After receiving the broadcast message, the satellite decrements the effective hop number segment value by 1;

[0056] Step 3.3: If the valid hop number field value is greater than 0, the message is forwarded to all satellites connected to the satellite except the source message satellite; if the valid hop number field value is less than or equal to 0, the message is not forwarded.

[0057] In step 8, the generation of forwarding rules includes the following steps:

[0058] Step 8.1: Optimal route calculation, performed by the gateway station based on a specific optimal route;

[0059] Step 8.2: Generate a forwarding path table. The forwarding path table is represented in the form S1→S2→…S k 1,2,…,k represent the satellites along the relay path;

[0060] Step 8.2: Compliance check: Satellites with the same forwarding path must not appear multiple times.

[0061] In step 9, forwarding data to the destination includes the following steps:

[0062] Step 9.1: S1, S2, ..., S k After receiving the data, each satellite retrieves its own location in S1→S2→…S k The location in the middle and the information of the next hop satellite;

[0063] Step 9.2: After successfully forwarding to the next satellite, send a reply indicating that forwarding is normal to the previous satellite;

[0064] Step 9.3: If the current satellite is the destination satellite, send a normal delivery reply to the previous satellite.

[0065] The constellation is a polar orbit constellation. The constellation topology is stored in a lightweight manner using two matrices A1 and A2, respectively, based on the horizontal and vertical connection relationships. They are represented as follows:

[0066]

[0067] A1 is a horizontal connection matrix, representing the horizontal connection relationships of constellations. If there is no connection, it is represented by 0; if there is a connection, it is represented by 1.

[0068] A2 is a vertical connection matrix, representing the vertical connection relationship of constellations. If there is no connection, it is represented by 0; if there is a connection, it is represented by 1.

[0069] Those skilled in the art will understand that, in addition to implementing the system, apparatus, and their modules provided by this invention in purely computer-readable program code, the same program can be implemented in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers by logically programming the method steps. Therefore, the system, apparatus, and their modules provided by this invention can be considered a hardware component, and the modules included therein for implementing various programs can also be considered structures within the hardware component; alternatively, modules for implementing various functions can be considered both software programs implementing the method and structures within the hardware component.

[0070] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A lightweight inter-satellite routing implementation method suitable for VDES constellations, characterized in that, include: Step 1: Based on constellation information, develop a mission plan at the gateway station, dividing the future mission time period into n time periods ΔT1, ΔT2, ..., ΔT n ; Step 2: Based on the satellite's visibility to the gateway station, from the time period ΔT i It is evident that a satellite S is selected from the satellite group of the gateway station. i As the satellite connecting the gateway stations, it is named the time period ΔT. i The central satellite; Step 3: At the gateway station, transmit the central satellite information (ΔT1,S1), (ΔT2,S2), ..., (ΔT) via uplink. n ,S n The information is uploaded to the current central satellite, which then broadcasts it to the entire constellation. Step 4: Each satellite in the constellation during time period ΔT i S i Set as the end node; Step 5: After receiving the uplink information from the ground, the satellite VDES payload encapsulates it into IP packets and forwards them to the satellite's onboard router. The onboard router replaces the destination IP address of the payload packets with S... n IP address; Step 6: Use the shortest path algorithm to complete the route planning, and forward the next hop according to the planning result; Step 7: Data is sent to the central satellite S i Then, the central satellite transmits the data to the gateway station via the feeder link; Step 8: After data processing at the gateway station, generate uplink data as needed, and attach forwarding rules to the uplink data according to the constellation's operating status to generate uplink messages; Step 9: After receiving the uplink message, the satellite forwards the data to the destination satellite according to the predetermined path and forwarding rules; Step 10: The onboard router queries its own busy / idle status. When it is busy, it retrieves the data packets to be forwarded and writes them to the storage module. When it is idle, it retrieves the data packets in the storage module one by one, determines whether to forward them or replace the corresponding destination address based on the source and destination addresses. In step 3, the process of the central satellite broadcasting information to the entire constellation is as follows: in the broadcast message, the effective hop count is set, and the effective hop count shall not exceed 1 / 3 of the total number of satellites; After receiving a broadcast message, the satellite decrements the valid hop number field value by 1; if the valid hop number field value is greater than 0, the message is forwarded to all satellites connected to the satellite except the source satellite; if the valid hop number field value is less than or equal to 0, the message is not forwarded.

2. The lightweight inter-satellite routing implementation method for VDES constellations according to claim 1, characterized in that, In step 1, the time period ΔT i The description is: ΔT i =[T ia -T m ,T ib -T n ]; Among them, [T ia ,T ib [T] represents the satellite transit time interval. m and T n These represent the remaining time for entry and exit, respectively, i = 1, 2, ..., n.

3. The lightweight inter-satellite routing implementation method for VDES constellations according to claim 1, characterized in that, In step 2, the selection process for the central satellite is as follows: based on the duration T1 of the satellite's transit over the ground station and the overlap time T2 with the transit time of the previous satellite, calculate aT1+bT2, where a and b are empirical parameters, and select the satellite with the larger aT1+bT2 transit time during the same period.

4. The lightweight inter-satellite routing implementation method for VDES constellations according to claim 1, characterized in that, In step 8, the forwarding rules include: optimal route calculation, performed by the gateway station based on a specific optimal route; and generating a forwarding path table, which is expressed in the form of: S1→S2→…S k 1,2,…,k represent the satellites on the forwarding path; compliance checks limit the number of times satellites with the same forwarding path appear.

5. The lightweight inter-satellite routing implementation method for VDES constellations according to claim 1, characterized in that, In step 8, the data processing of the gateway station includes data reception and storage, parsing and splicing of data packet formats, and recovery of the original information.

6. The lightweight inter-satellite routing implementation method for VDES constellations according to claim 1, characterized in that, In step 9, data forwarding to the destination includes: S1, S2, ..., S... k After receiving the data, each satellite retrieves its own location in S1→S2→…S k The system retrieves the location of the satellite and information about the next hop satellite; after successfully forwarding to the next satellite, it sends a forwarding success message to the previous satellite; if the current satellite is the destination satellite, it sends a delivery success message to the previous satellite.

7. The lightweight inter-satellite routing implementation method for VDES constellations according to claim 1, characterized in that, In step 10, if the destination address is the central satellite and the router is located on the current central satellite, then no forwarding is performed; if the destination address is the central satellite corresponding to a previous time, then the destination address is replaced with the current central satellite before forwarding. If the destination address is not the central satellite at any previous time, no replacement will be made, and the route will be forwarded according to the shortest path routing plan result.

8. The lightweight inter-satellite routing implementation method for VDES constellations according to claim 1, characterized in that the constellation For polar orbit constellations, the constellation topology is stored in lightweight form as two matrices A1 and A2, representing the horizontal and vertical connections respectively. Where A1 is the horizontal connection matrix, representing the horizontal connection relationship of constellations. If there is no connection, it is represented as 0, and if there is a connection, it is represented as 1. A2 is the vertical connection matrix, representing the vertical connection relationship of constellations. If there is no connection, it is represented as 0, and if there is a connection, it is represented as 1.

9. A lightweight inter-satellite routing implementation system suitable for VDES constellations, characterized in that, The lightweight inter-satellite routing implementation method for the VDES constellation is adopted according to any one of claims 1 to 8.

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