An inter-satellite network for a globally networked constellation of observation satellites

Abstract

The application relates to the technical field of inter-satellite network information transmission, and provides an inter-satellite network for a global networking observation satellite constellation, wherein the inter-satellite network is obtained by constructing an inter-satellite network optimization problem and solving the inter-satellite network optimization problem based on a load-weighted Dijkstra method. The inter-satellite network optimizes the average transmission delay of inter-satellite links, guarantees high-timeliness transmission of important information, effectively enables traffic on a single link to be transmitted through multiple paths to realize load balancing, avoids link congestion in the network, and good link balancing effect is obtained.

Description

Technical Field

[0001] This invention generally relates to the field of inter-satellite network information transmission technology. Specifically, this invention relates to an inter-satellite network for a global constellation of observation satellites. Background Technology

[0002] A global satellite constellation typically consists of multiple orbital planes, with multiple satellites evenly distributed across each plane. Satellites in this constellation transmit information via inter-satellite links, which are bidirectional. Each satellite has four inter-satellite links: two long-term inter-satellite links within the orbital plane, maintaining continuous communication with adjacent satellites within that plane; and two inter-satellite links between orbital planes, which are established sequentially with satellites in the east and west adjacent orbital planes based on their visibility relationships. The duration of these inter-satellite links varies at different times.

[0003] A global constellation of observation satellites needs to ensure information transmission between any satellites in the network at any given time. Existing technologies typically use single-strategy methods for information transmission, such as the LHP (Least Hops Path) method, which can lead to link congestion due to information transmission being concentrated on a few or even a single inter-satellite link. Summary of the Invention

[0004] To at least partially solve the link congestion problem caused by the concentration of information transmission on a few or even a single inter-satellite link during information transmission in existing global network observation satellite constellations, this invention proposes an inter-satellite network for global network observation satellite constellations.

[0005] The inter-satellite network is used to represent the inter-satellite information transmission of a globally networked observation satellite constellation. An inter-satellite network optimization problem is constructed to optimize inter-satellite network latency and traffic load. The latency optimization is constructed as a first optimization problem, expressed as the following equation:

[0006]

[0007] in, This represents the delay optimization objective function. Indicates the first Transmission delay weight of each message Indicates the first The first information transmission path selected Strip and Represents the speed of light; and

[0008] The traffic load optimization for inter-satellite networks is conceived as a second optimization problem, which is expressed as follows:

[0009]

[0010] in, This represents the objective function for traffic optimization. Indicates the first The transmission traffic weight of each piece of information Indicates the first The transmission traffic of the message Indicates confirmation A function to determine whether it is on the transmission path; and

[0011] Solving the inter-satellite network optimization problem based on the load-weighted Dijkstra method includes the following steps:

[0012] Determine the inter-satellite link connectivity matrix of the inter-satellite network;

[0013] Prioritize the information to be transmitted;

[0014] Determine the maximum load on the inter-satellite link; and

[0015] Calculating the transmission path of information based on Dijkstra's method includes the following steps:

[0016] Calculate the transmission path weighting matrix, which includes the Dijkstra weights of the inter-satellite links. In the first calculation, the transmission delay of each inter-satellite link is calculated as the Dijkstra weight of each inter-satellite link based on the transmission path length.

[0017] For the highest priority information, calculate the Dijkstra shortest path to generate the Dijkstra shortest transmission path;

[0018] Calculate the load of each inter-satellite link on the Dijkstra shortest transmission path;

[0019] Based on the maximum load, calculate whether any inter-satellite links exceed the maximum load. If so, exclude the inter-satellite links exceeding the maximum load and recalculate Dijkstra's algorithm. If not, generate new Dijkstra's weights based on the accumulated load of each inter-satellite link and update the transmission path weighting matrix.

[0020] Repeat the steps above for calculating the information transmission path based on the Dijkstra method, from highest to lowest priority.

[0021] In one embodiment of the present invention, the connection relationship of the inter-satellite network is represented as satellite nodes. and the edges between satellite nodes ;

[0022] The connectivity of inter-satellite links in an inter-satellite network is represented as an inter-satellite link connectivity matrix. ,in Indicates satellite node and Inter-satellite link connectivity between them; and

[0023] The information transmission path between satellites is represented as the information originating from the source satellite node. Transmitted to the destination satellite node Passing by As shown in the following formula:

[0024]

[0025] in, Indicates from the source satellite node Transmitted to the destination satellite node After the first Edge.

[0026] In one embodiment of the present invention, it is specified that, based on satellite nodes... and Inter-satellite transmission distance Determine the satellite node and Inter-satellite link connectivity It can be expressed as the following formula:

[0027]

[0028] in, These represent the minimum and maximum inter-satellite transmission distances between satellite nodes in the inter-satellite network, respectively.

[0029] In one embodiment of the present invention, a minimum inter-satellite transmission distance is specified. Determined based on the satellite's observation capabilities; and

[0030] Maximum inter-satellite transmission distance Calculate according to the following formula:

[0031]

[0032] in, Indicates the satellite's altitude. Represents the radius of the Earth. The maximum communication geocentric angle is expressed as .

[0033] In one embodiment of the present invention, it is specified that the path includes a function. Whether an edge is included in the path is determined by the following formula:

[0034] .

[0035] In one embodiment of the present invention, the information to be transmitted is prioritized according to the task type and data type of the information to be transmitted.

[0036] In one embodiment of the present invention, the sum of each type of information to be transmitted is calculated based on the amount of data of the information to be transmitted, and the maximum load of the inter-satellite link is determined, wherein the maximum load includes 2 / 3 bandwidth or 1 / 2 bandwidth.

[0037] This invention offers at least the following advantages: By employing a low-latency transmission strategy for high-priority information, and distributing high-load link traffic while using higher-latency links for low-priority information (within the maximum latency requirement), traffic balance is achieved. Compared to existing information transmission methods based on a single strategy, this invention optimizes the average transmission latency of inter-satellite links, ensuring timely delivery of important information. Furthermore, it effectively enables multi-path transmission of traffic on a single link to achieve load balancing, avoiding link congestion in the network and achieving better link balancing. Attached Figure Description

[0038] To further illustrate the advantages and other features of the various embodiments of the present invention, a more specific description of the embodiments of the present invention will be presented with reference to the accompanying drawings. It is understood that these drawings depict only typical embodiments of the invention and are therefore not intended to limit its scope. In the drawings, identical or corresponding parts will be indicated by the same or similar reference numerals for clarity.

[0039] Figure 1 A schematic diagram of the network topology of a global networked observation satellite constellation according to one embodiment of the present invention is shown.

[0040] Figure 2 A flowchart illustrating the solution of the inter-satellite network optimization problem based on the load-weighted Dijkstra method in one embodiment of the present invention is shown.

[0041] Figure 3 A schematic diagram of the transmission delay distribution of an inter-satellite network in one embodiment of the present invention is shown.

[0042] Figure 4 A schematic diagram comparing the inter-satellite link load in one embodiment of the present invention with that in the prior art is shown.

[0043] Figure 5This diagram illustrates the principle of calculating the maximum inter-satellite transmission distance in an embodiment of the present invention. Detailed Implementation

[0044] It should be noted that the components in the various figures may be shown exaggeratedly for illustrative purposes and are not necessarily to scale. In each figure, the same reference numerals are used for components that are identical or have the same function.

[0045] In this invention, unless otherwise specified, "arranged on," "arranged above," and "arranged on" do not exclude the possibility of an intermediate element between them. Furthermore, "arranged on or above" merely indicates the relative positional relationship between two components, and in certain cases, such as when the product orientation is reversed, it can also be converted to "arranged below or under," and vice versa.

[0046] In this invention, the various embodiments are merely intended to illustrate the solutions of the invention and should not be construed as limiting.

[0047] In this invention, unless otherwise specified, the quantifiers “a” and “one” do not exclude scenarios involving multiple elements.

[0048] It should also be noted that, in the embodiments of the present invention, only a portion of the components or parts may be shown for clarity and simplicity. However, those skilled in the art will understand that, under the teachings of the present invention, necessary components or parts can be added as needed for specific scenarios. Furthermore, unless otherwise stated, features in different embodiments of the present invention can be combined with each other. For example, a feature in the second embodiment can replace a corresponding or functionally identical or similar feature in the first embodiment, and the resulting embodiment will also fall within the scope of disclosure or description of this application.

[0049] It should also be noted that, within the scope of this invention, the terms "same," "equal," and "equal to" do not imply that the two values ​​are absolutely equal, but rather allow for a certain reasonable margin of error. In other words, the terms also encompass "substantially the same," "substantially equal," and "substantially equal to." Similarly, in this invention, the directional terms "perpendicular to," "parallel to," etc., also encompass the meanings of "substantially perpendicular to" and "substantially parallel to."

[0050] Furthermore, the numbering of the steps in the methods of the present invention does not limit the execution order of the method steps. Unless otherwise specified, the method steps may be executed in different orders.

[0051] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0052] First, a mathematical model of the global satellite constellation network needs to be developed. Taking the first constellation as an example, such as... Figure 1 As shown, the first constellation comprises four fixed orbital planes with the same inclination, right ascension of the ascending node evenly distributed at the equator, the same orbital altitude, and the same orbital period. The satellites within each orbital plane are also evenly distributed. Eight satellites are evenly distributed on each orbital plane, and each satellite is numbered: orbital plane 1 is numbered from sat11 to sat18, orbital plane 2 from sat21 to sat28, orbital plane 3 from sat31 to sat38, and orbital plane 4 from sat41 to sat48.

[0053] The connections within a constellation network can be represented as follows: ,in Indicates satellite nodes, This represents the edge between adjacent satellite nodes. middle, Satellites sat11-sat18 corresponding to orbital plane 1, The satellites corresponding to orbital plane 2 are sat21-sat28. Satellites corresponding to orbital plane 3, Sat31-Sat38, The corresponding satellite is sa41-sa48 in orbital plane 4.

[0054] The connectivity of inter-satellite links between satellites can be represented as satellite nodes. and Inter-satellite link connectivity matrix .

[0055] Based on satellite nodes and Inter-satellite transmission distance Determine satellite nodes and Inter-satellite link connectivity It can be expressed as the following formula:

[0056]

[0057] in, These represent the minimum and maximum inter-satellite transmission distances between satellite nodes in the constellation network, respectively.

[0058] Minimum inter-satellite transmission distance The angle of the satellite antenna can be adjusted based on the satellite's own observation capabilities.

[0059] Maximum inter-satellite transmission distance The calculation can be as follows Figure 5 As shown, the two farthest satellites in the constellation network are set to the same distance as the Earth's center, and the satellite altitude is represented as... The radius of the Earth is expressed as The maximum communication geocentric angle between two satellites that are furthest apart is expressed as... And will increase the maximum inter-satellite transmission distance The calculation can be expressed as the following formula:

[0060]

[0061] By determining the inter-satellite link connectivity relationships between each satellite, the inter-satellite link connectivity matrix can be established. It can be expressed as the following formula:

[0062] .

[0063] The information transmission path between satellites includes the edges that the information needs to pass through from the source satellite node to the destination satellite node, and is expressed as follows:

[0064]

[0065] This indicates the th mileage from the source satellite node to the destination satellite node. Edge.

[0066] Functions can be included via paths The path inclusion function, which determines whether an edge is included in a path, can be expressed as follows:

[0067]

[0068] If the link is in the transmission path, then The value is 1.

[0069] To address the link congestion problem during information transmission in existing technologies, this invention proposes optimizing the information transmission path during transmission. High-priority information is transmitted via links with lower latency. While not exceeding the maximum latency requirement, high-load link traffic is distributed, and low-priority information is transmitted via links with higher latency, thereby achieving traffic balance.

[0070] The optimization objective of the information transmission path can be expressed as an optimization objective function, which is expressed as:

[0071] First objective function: ;

[0072] in, This represents the delay optimization objective function. Indicates the first Transmission delay weight of each message Indicates the first The first information transmission path selected Strip and Let represent the speed of light. The objective function of the first objective function is to minimize the time delay.

[0073] And the second objective function:

[0074] in, This represents the objective function for traffic optimization. Indicates the first The transmission traffic weight of each piece of information Indicates the first The transmission traffic of the message Indicates confirmation The function determines whether something is on the transmission path. The objective function optimizes to determine the link. The minimum value of the maximum load on the device.

[0075] like Figure 2 As shown, the optimization process of the information transmission path can be solved using the load-weighted Dijkstra method. The solution process includes the following steps:

[0076] Step 1: Calculate the connectivity between nodes based on the inter-satellite transmission distances between satellites in the global satellite constellation, forming a connectivity matrix. Simultaneously, prioritize all information to be transmitted according to task and data type. Calculate the total data volume for each type of information based on the initial data volume, and determine the maximum load on a single link, such as 2 / 3 or 1 / 2 bandwidth.

[0077] Step 2: Calculate the weighted matrix of the transmission paths. In the first calculation, the transmission delay of each link is calculated as the weight of each link based on the transmission path length.

[0078] Step 3: Calculate the shortest path using Dijkstra's algorithm for the highest priority information to generate the shortest transmission path.

[0079] Step 4: Calculate the load on each link in the transmission path.

[0080] Step 5: Based on the expected load, calculate whether any links exceed the maximum load. If so, exclude the links exceeding the maximum load and recalculate Dijkstra's algorithm. If no links exceed the maximum load, generate new weighted values ​​based on the accumulated load of each link and update the transmission path weighting matrix.

[0081] Step 6: Repeat steps 2 through 5 in order of priority until the calculation is complete.

[0082] The method of this invention initializes the load target at the beginning of information transmission by comprehensively considering the transmission load. Then, the transmitted information is prioritized and transmitted starting from the highest priority target. The path with the lowest latency is solved using the Dijktra method. After the path is determined, the load on the link generated by the priority transmission is calculated and added as a weight to the transmission path. Thus, the load is included as a cost in the selection of lower priority information paths, and the maximum complexity of a single path is constrained by the expected load.

[0083] In one embodiment of the method of the present invention, simulation analysis is performed, and the type, length, and priority of the input information are shown in Table 1:

[0084]

[0085] Table 1

[0086] The information length is related to the number of satellites and targets, and needs to be multiplied by these quantities during simulation. In information priority, information types with higher numerical values ​​have higher priority. The simulation uses randomly distributed information senders across the entire network and nodes within five hops of the shortest path as the receiving end. The number of targets is set to 55 for simulation analysis. The maximum link transmission rate is 10 Mbps.

[0087] The transmission delay of the above information is solved using the method of this invention, and the solution is as follows: Figure 3 As shown. Figure 3 In the diagram, the x-axis and y-axis coordinates represent the satellite numbers, and the z-axis coordinate represents the minimum transmission delay at time T0 after optimization using the method of this invention from satellite number x to satellite number y. The diagonal line in the middle of the diagram represents the delay from satellite to itself, so all values ​​are zero. Since all links are assumed to be bidirectional, the final distribution diagram should be perfectly symmetrical without considering load optimization. Due to load considerations, there are some differences in the delay distribution. After optimization, the overall delay is reduced by an average of approximately 30ms compared to the LHP method. The point-to-point transmission delay in the constellation network is approximately 100ms, ensuring the timely delivery of important information.

[0088] like Figure 4As shown, the load of the proposed method is compared with that of the LHP method. The upper line represents the maximum load on a single link within one topology cycle based on the LHP method. It can be seen that, therefore, transmission based on the LHP method can generate excessive load on a single link in certain transmission scenarios, such as at time T0 and 600s in the figure. Since the maximum transmission rate of the link is 10Mbps, congestion occurs on some links in multiple time slices. The lower line, based on the proposed method, achieves link balancing by weighting the transmission matrix based on load. It can be seen that, firstly, the maximum transmission load of a single link decreases overall compared to the LHP strategy; within the entire simulation cycle, the maximum load of a single link is never greater than the maximum load under LHP. Furthermore, the change in the maximum load of a single link is relatively stable throughout the entire cycle. Therefore, the proposed method can effectively enable traffic on a single link to achieve load balancing through multi-path transmission, avoiding link congestion in the network and achieving a better link balancing effect.

[0089] Although various embodiments of the invention have been described above, it should be understood that they are presented by way of example only and not as limitations. It will be apparent to those skilled in the art that various combinations, modifications, and alterations can be made without departing from the spirit and scope of the invention. Therefore, the breadth and scope of the invention disclosed herein should not be limited by the exemplary embodiments disclosed above, but should be defined solely by the appended claims and their equivalents.

Claims

1. An inter-satellite network system for a global constellation of observation satellites, wherein the system comprises four fixed orbital planes, each with eight satellites evenly distributed, characterized in that, The inter-satellite network is used to represent the inter-satellite information transmission of a globally networked observation satellite constellation. An inter-satellite network optimization problem is constructed to optimize inter-satellite network latency and traffic load. The latency optimization is constructed as a first optimization problem, expressed as the following equation: in, This represents the delay optimization objective function. Indicates the first Transmission delay weight of each message Indicates the first The first information transmission path selected Strip and Represents the speed of light; and The traffic load optimization for inter-satellite networks is conceived as a second optimization problem, which is expressed as follows: in, This represents the objective function for optimizing traffic load. Indicates the first The transmission traffic weight of each piece of information Indicates the first The transmission traffic of the message Indicates confirmation A function to determine whether it is on the transmission path; and Solving the inter-satellite network optimization problem based on the load-weighted Dijkstra method includes the following steps: Determine the inter-satellite link connectivity matrix of the inter-satellite network; Prioritize the information to be transmitted; Determine the maximum load on the inter-satellite link; and Calculating the transmission path of information based on Dijkstra's method includes the following steps: Calculate the transmission path weighting matrix, which includes the Dijkstra weights of the inter-satellite links. In the first calculation, the transmission delay of each inter-satellite link is calculated as the Dijkstra weight of each inter-satellite link based on the transmission path length. For the highest priority information, calculate the Dijkstra shortest path to generate the Dijkstra shortest transmission path; Calculate the load of each inter-satellite link on the Dijkstra shortest transmission path; Based on the maximum load, calculate whether any inter-satellite links exceed the maximum load. If so, exclude the inter-satellite links exceeding the maximum load and recalculate Dijkstra's algorithm. If not, generate new Dijkstra's weights based on the accumulated load of each inter-satellite link and update the transmission path weighting matrix. Repeat the steps above for calculating the information transmission path based on the Dijkstra method, from highest to lowest priority.

2. The inter-satellite network system for a global constellation of observation satellites according to claim 1, characterized in that: The connectivity of the inter-satellite network is represented as satellite nodes. and the edges between satellite nodes ; The connectivity of inter-satellite links in an inter-satellite network is represented as an inter-satellite link connectivity matrix. ,in Indicates satellite node and Inter-satellite link connectivity between them; and The information transmission path between satellites is represented as the information originating from the source satellite node. Transmitted to the destination satellite node Passing by As shown in the following formula: in, Indicates from the source satellite node Transmitted to the destination satellite node After the first Edge.

3. The inter-satellite network system for a global networked observation satellite constellation according to claim 2, characterized in that: According to satellite nodes and Inter-satellite transmission distance Determine the satellite node and Inter-satellite link connectivity It can be expressed as the following formula: in, These represent the minimum and maximum inter-satellite transmission distances between satellite nodes in the inter-satellite network, respectively.

4. The inter-satellite network system for a global constellation of observation satellites according to claim 3, characterized in that: Minimum inter-satellite transmission distance Determined based on the satellite's observation capabilities; and Maximum inter-satellite transmission distance Calculate according to the following formula: in, Indicates the satellite's altitude. Represents the radius of the Earth. The maximum communication geocentric angle is expressed as .

5. The inter-satellite network system for a global networked observation satellite constellation according to claim 3, characterized in that: Functions included via path Whether an edge is included in the path is determined by the following formula: 。 6. The inter-satellite network system for a global networked observation satellite constellation according to claim 5, characterized in that: Prioritize the information to be transmitted based on the task type and data type.

7. The inter-satellite network system for a global networked observation satellite constellation according to claim 5, characterized in that: The total amount of each type of information to be transmitted is calculated based on the amount of data to be transmitted, and the maximum load of the inter-satellite link is determined, which includes 2 / 3 bandwidth or 1 / 2 bandwidth.

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